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3/8/2016 - Regular
Roanoke County Board of Supervisors INVOCATION: Pastor Dolph Painter Mt. Olive Primitive Baptist Church March 8, 2016 PLEDGE OF ALLEGIANCE TO THE UNITED STATES FLAG Disclaimer: "Any invocation that may be offered before the official start of the Board meeting shall be the voluntary offering of a private citizen, to and for the benefit of the Board. The views or beliefs expressed by the invocation speaker have not been previously reviewed or approved by the Board and do not necessarily represent the religious beliefs or views of the Board in part or as a whole. No member of the community is required to attend or participate in the invocation and such decision will have no impact on their right to actively participate in the business of the Board." Page 1 of 5 Roanoke County Board of Supervisors Agenda March 8, 2016 NOTE: A meeting of the Audit Committee has been scheduled for 2:00 p.m. in the Fourth Floor Training Room, 5204 Bernard Drive, Roanoke, VA 24018 Good afternoon and welcome to our meeting for March 8, 2016. Regular meetings are held on the second and fourth Tuesday at 3:00 p.m. Public hearings are held at 7:00 p.m. on the fourth Tuesday of each month. Deviations from this schedule will be announced. The meetings are broadcast live on RVTV, Channel 3, and will be rebroadcast on Friday at 7:00 p.m. and on Sunday at 4:00 p.m. Board of Supervisors meetings can also be viewed online through Roanoke County's website at www.RoanokeCountyVA.gov. Our meetings are closed -captioned, so it is important for everyone to speak directly into the microphones at the podium. Individuals who require assistance or special arrangements to participate in or attend Board of Supervisors meetings should contact the Clerk to the Board at (540) 772-2005 at least 48 hours in advance. Please turn all cell phones off or place on silent. A. OPENING CEREMONIES (3:00 p.m.) 1. Roll Call B. REQUESTS TO POSTPONE, ADD TO OR CHANGE THE ORDER OF AGENDA ITEMS C. PROCLAMATIONS, RESOLUTIONS, RECOGNITIONS AND AWARDS 1. Proclamation declaring the month of March as American Red Cross Month in the County of Roanoke (Nicole Brown-Kasey, Administrative Coordinator) D. BRIEFINGS Briefing to review costs for County departments associated with two snow events, January 22, 2016 and February 14, 2016 (Stephen G. Simon, Chief of Fire and Rescue; Rebecca Owens, Director of Finance) Page 2 of 5 E F G 2. Presentation of the proposed fiscal year 2016-2017 Operating Budget (Thomas C. Gates, County Administrator; Christopher Bever, Director of Management and Budget) NEW BUSINESS 1. Resolution approving recommendations from the Pipeline Advisory Committee for filing with the Federal Energy Regulatory Commission regarding the Mountain Valley Pipeline project (Richard L. Caywood, Assistant County Administrator) 2. Resolution requesting changes in the Virginia Department of Transportation Primary and Secondary System of State Highways, Route 221, Bent Mountain Road; Route 688, Cotton Hill Road; Route 745, Ran Lynn Drive; Route 957, Sunnycrest Loop, Cave Spring and Windsor Hills Magisterial District (Arnold Covey, Director of Community Development) 3. Resolution adopting revisions to the Stormwater Management Design Manual for Roanoke County (Arnold Covey, Director of Community Development) FIRST READING OF ORDINANCES 1. Ordinance accepting and appropriating $4,000 for printing costs of the K, 1, and 2 grade level instructional materials to support the County literacy plan (Rebecca Owens, Director of Finance) 2. Ordinance accepting and appropriating funds in the amount of $27,500 to Roanoke County Public Schools from the National Board for Professional Teaching Standards for teacher incentives (Rebecca Owens, Director of Finance) 3. Ordinance accepting and appropriating funds in the amount of $2,300 to Roanoke County Public Schools from Share Our Strength and the Virginia No Kid Hungry Campaign to expand the breakfast program at Northside High School (Rebecca Owens, Director of Finance) 4. Ordinance authorizing the conveyance of the Roland E. Cook Building to Old School Partners, LLC (Ruth Ellen Kuhnel, County Attorney) APPOINTMENTS 1. Board of Zoning Appeals (BZA) (appointed by District) 2. Budget and Fiscal Affairs Committee (BFAC) (appointed by District and At Large) Page 3 of 5 3. Clean Valley Council (At Large) 4. Economic Development Authority (EDA) (appointed by District) 5. Parks, Recreation and Tourism Advisory Commission (appointed by District) H. CONSENT AGENDA ALL MATTERS LISTED UNDER THE CONSENT AGENDA ARE CONSIDERED BY THE BOARD TO BE ROUTINE AND WILL BE ENACTED BY ONE RESOLUTION IN THE FORM OR FORMS LISTED BELOW. IF DISCUSSION IS DESIRED, THAT ITEM WILL BE REMOVED FROM THE CONSENT AGENDA AND WILL BE CONSIDERED SEPARATELY 1. Approval of Minutes — January 12, 2016 2. Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Charles Paitsel, Solid Waste Operations Supervisor, upon his retirement after more than forty-four (44) years of service 3. Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Diane L. Guerrant, Library Assistant, upon her retirement after more than twenty-seven (27) years of service 4. Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Penny K. Lloyd, Administrative and Marketing Manager, upon her retirement after eight (8) years of service 5. Resolution requesting acceptance of Paddington Station Lane, Queens Way and Stewart View Terrace into the Virginia Department of Transportation Secondary system 6. Confirmation of appointment to the Local Office on Aging (LOA) Advisory Council; Parks, Recreation and Tourism Committee (District) 7. Request for ratification of appointments of representatives to the Roanoke County Community Policy and Management Team (CPMT) CITIZENS' COMMENTS AND COMMUNICATIONS J. REPORTS 1. General Fund Unappropriated Balance 2. Capital Reserves 3. Reserve for Board Contingency Page 4 of 5 4. Outstanding Debt K. REPORTS AND INQUIRIES OF BOARD MEMBERS 1. George G. Assaid 2. Al Bedrosian 3. Martha B. Hooker 4. Joseph P. McNamara 5. P. Jason Peters L. WORK SESSIONS 1. Joint work session with Roanoke County Public School Board to discuss various items M. CLOSED MEETING, pursuant to the Code of Virginia as follows: 1. Section 2.2-3711.A.5 Discussion concerning the disposition of publicly held real property, where discussion in an open meeting would adversely affect the bargaining position or negotiating strategy of the County, namely the 419 Library N. CERTIFICATION RESOLUTION O. ADJOURNMENT Page 5 of 5 ACTION NO. ITEM NO. C-1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: AGENDA ITEM: SUBMITTED BY: APPROVED BY: March 8, 2016 Proclamation declaring the month of March as American Red Cross Month in the County of Roanoke Deborah C. Jacks Chief Deputy Clerk to the Board Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: The American Red Cross has requested the Board of Supervisors proclaim the month of March as American Red Cross Month in the County of Roanoke Nichole Brown Kasey, Administrative Coordinatorwith the American Red Cross is expected to attend the meeting to accept the proclamation Page 1 of 1 C-1 � uun#g of Ywanjakr 2 � 2 _ 83 PROCLAMATION DECLARING THE MONTH OF MARCH AS AMERICAN RED CROSS MONTH IN THE COUNTY OF ROANOKE WHEREAS, March is American Red Cross Month - a special time to recognize and thank our heroes — those who volunteer, donate blood, take life-saving courses or provide financial donations to support an organization whose mission is to help those in need; and WHEREAS, we would like to remember those who help all of us here in Roanoke County by giving their time to help their neighbors, and thank our heroes — our volunteers, blood donors, class takers and financial supporters who help us assist those in need; and WHEREAS, in Roanoke County, the Red Cross works tirelessly through its employees and volunteers to help when disaster strikes, when someone needs life-saving blood, or the comfort of a helping hand. It provides 24-hour support to members of the military, veterans and their families, and provides training in CPR, aquatics safety, and first aid; and WHEREAS, across the country, the American Red Cross responds to nearly 70,000 disasters a year. It provides some 400,000 services to military members, veterans and civilians, collects and distributes about forty percent (40%) of the nation's blood supply and trains more than seven million people in first aid, water safety and other life-saving skills every year WHEREAS, our community depends on the American Red Cross, which relies on donations of time, money and blood to fulfill its humanitarian mission. Despite these challenging economic times, the American Red Cross continues to offer help and comfort to those in need. NOW, THEREFORE, We, the Board of Supervisors of Roanoke County, Virginia, do hereby proclaim and recognize the month of March 2016 as "AMERICAN RED CROSS MONTH" throughout the County of Roanoke; and FURTHER, by this proclamation, we give notice to our citizens to acknowledge the important role the American Red Cross plays in our society and encourage the citizens of Roanoke County to support this organization and its noble humanitarian mission. Presented this Beth day of March 2016 George Assaid���L�^ Al Bedrosia Martha Hooker J09491bh P. McNarn P. Jaso Peters ACTION NO. ITEM NO. D-1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Briefing to review costs for County departments associated with two snow events, January 22, 2016 and February 14, 2016 SUBMITTED BY: Stephen G. Simon Chief of Fire and Rescue APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: Roanoke County received two significant snow/ice events within a four (4) week period beginning January 22, 2016 through February 19, 2016. The first event occurred on January 22, 2016, and ended with storm totals generally from sixteen to eighteen (16 to 18) inches. During the storm the Emergency Communications Center handled 1071 calls resulting in 91 Fire and Rescue responses, 204 Police responses, 41 Vinton Police responses and 19 Sheriff's responses. Snow removal and cleanup operations handled by Parks and Recreation, Community Development, and Sheriff's Office (Inmate Program) required 1,241 work hours at thirty-five (35) County facilities. The second event occurred on February 14, 2016, and ended with storm totals generally from six to eight (6 to 8) inches. During this storm, the ECC handled 2023 calls resulting in 194 Fire and Rescue responses, 260 Police responses, 78 Vinton Police responses and 31 Sheriff's responses. Snow removal and cleanup operations for this storm took 759 hours to complete. As an additional complication, winds and ice associated with this storm downed trees resulting in wide -spread power outages. Emergency personnel spent numerous hours removing trees from roadways and assisting citizens when not handling serious incidents. We are pleased to report that all emergency incidents were handled seamlessly, however the County -wide response to these storms resulted in additional costs that were not Page 1 of 2 included in the budget for these County departments. January 22, 2016 February 14, 2016 Overtime costs for Fire & Rescue, Parks, Recreation, and Tourism, Police, Community Development and Sheriff's Office Operational Costs/Vehicle Repairs Total Total $ 18,429.24 $ 4,428.17 $ 22,857.41 17,025.63 5,805.55 22,831.18 $ 35,454.87 $ 10,233.72 $ 45,688.59 FISCAL IMPACT: Overtime and operational costs of $45,688.59 will be accounted within the departments 2015-2016 budgets. Page 2 of 2 ACTION NO. ITEM NO. D-2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Presentation of the proposed fiscal year 2016-2017 Operating Budget SUBMITTED BY: Thomas C. Gates, County Administrator; Christopher Bever, Director of Management and Budget APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: This time has been scheduled to provide the Board of Supervisors with a briefing on the County Administrator's proposed fiscal year 2016-2017 operating budget. The proposed operating budget document and the presentation, which will provide an overview of the budget, will be distributed to the Board of Supervisors at the March 8, 2016 meeting. Page 1 of 1 ACTION NO. ITEM NO. E-1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY. VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Resolution approving recommendations from the Pipeline Advisory Committee for filing with the Federal Energy Regulatory Commission regarding the Mountain Valley Pipeline project SUBMITTED BY: Richard L. Caywood Assistant County Administrator APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: On October 23, 2015, Mountain Valley Pipeline (MVP) made its formal project application, with the Federal Energy Regulatory Commission to construct a 42" high-pressure, natural gas transmission pipeline from the Marcellus and Utica shale gas fields near Mobley, West Virginia, to the Transco facility near Chatham, Virginia. The pipeline is 301 miles long with 8.3 miles of the project located in Roanoke County. On November 23, 2015, the Board of Supervisors passed a resolution authorizing staff to file as an intervenor with the Federal Energy Regulatory Commission. On December 24, 2015, the Federal Energy Regulatory Commission issued a 54 page document that contained hundreds of questions regarding MVP's project application. Many of these questions were highly technical in nature and a number of the questions raised were from previous comments from Roanoke County or its citizens. On January 15, 2016, January 27, 2016, and February 29, 2016, MVP filed responses to the Federal Energy Regulatory Commission responsive to its December 24, 2015 questions. Also on January 27, 2016, MVP filed a "Motion to Answer and Answer" that Page 1 of 5 addressed a number of topics that had been raised by intervenors such as Roanoke County. In fact, Roanoke County was specifically mentioned in several sections of this document. The Pipeline Advisory Committee met on February8, 2016 and February22, 2016 to begin its review and consideration of the large volume of materials from MVP. Staff has also been reviewing these materials as well as our outside counsel for the issues raised in the "Motion to Answer and Answer." The Pipeline Advisory Committee is seeking Board support in the form of a resolution to make additional filings with the Federal Energy Regulatory Commission as summarized below: Programmatic Environmental Impact Statement: Roanoke County's Motion of Intervention, approved by the Board of Supervisors on November 10, 2015, and filed with the Federal Energy Regulatory Commission November 24, 2015, specifically requests FERC to prepare a Programmatic Environmental Impact Statement (PEIS) to review the multiple natural gas transmission projects between the Marcellus Shale formations in West Virginia and Pennsylvania and the historic gulf coast / northeast gas transmission system that passes through Virginia. Excerpt from Roanoke County's Motion of Intervention: As the County stated in its Scoping Comments, "[t]here are at least three, if not more similar pipeline projects crossing Western Virginia under consideration today. They are the Mountain Valley Pipeline, The Atlantic Coast Pipeline and the Appalachian Connector Project. " The County requested that the Commission "require that a comprehensive study be made of the cumulative impact, and purpose and need of these projects and any similar projects." The County restates that request here, and submits that the most efficient way to conduct a comprehensive study of cumulative impact and need for these projects is to prepare a programmatic EIS. In its "Motion to Answer and Answers" filed with FERC on January 27, 2016, MVP specifically addressed Roanoke County's Motion of Intervention and our request for PEIS. Both Roanoke County staff and our outside counsel believe that MVP's arguments against a PEIS are tenuous. We also believe that FERC's position on PEISs in general is unreasonable. The Roanoke County Pipeline Advisory Committee and staff recommends filing a rebuttal to MVP's "Motion to Answer and Answer". We believe that this is important not only for this project but also to build the record should the County face the not unlikely prospect of additional natural gas pipeline transmission projects. This portion of our recommended filings with FERC will be prepared by our outside counsel. A draft copy of this document is attached. Page 2 of 5 Roanoke River Crossing and Watershed: The proposed crossing of the Roanoke River by the MVP is approximately 1.25 river miles upstream of the water intake for the Spring Hollow Reservoir. The Spring Hollow Reservoir is a side storage reservoir that uses river water as its primary water source. Only a small portion of the Spring Hollow Reservoir's total capacity is delivered by its watershed. The vast majority of the water in Spring Hollow Reservoir is Roanoke River water that is pumped into the reservoir. Impacts to the river can reduce its water quality and prevent the Water Authority from pumping into the reservoir. It is unclear if MVP recognizes the connection between the river and the reservoir. The Roanoke River also flows into Smith Mountain Lake which is also a source of public drinking water. Impacts to the watershed for the Roanoke River (North Fork and/or South Fork) have the potential to impact the water supply for a region with over 250,000 residents. We believe that FERC should treat the Roanoke River as a major waterbody crossing even though its width is less than 1 00'at the crossing nearest the Spring Hollow Reservoir. We believe that this is appropriate due to the immediate proximity to the primary water intake for the County's water supply. The Roanoke County Pipeline Advisory Committee and staff recommends that the Board of Supervisors approve staff making a filing with FERC regarding impacts to the Roanoke River and the Spring Hollow Reservoir. A map depicting the pipeline's crossing of the Roanoke River and the reservoir is attached. Steep Slopes: The current route of the MVP crosses some of the steepest terrain in Roanoke County. In particular the MVP crosses Poor Mountain and portions of Bent Mountain that have very steep slopes of 450 or greater. These very steep slopes also coincide with highly erodible soils. Steep slopes within Roanoke County create a series of risks for both the pipeline itself as well as surrounding properties and water resources. Many of these steep slopes are also overlain with highly erodible soils. To date, information from MVP regarding how these slopes will be crossed and the methods that will be used to protect water resources has been very limited. County GIS staff have prepared a map for submission to FERC that shows the rate of slopes along the route of the MVP through the County. The Roanoke County Pipeline Advisory Committee and staff recommends that the Board of Supervisors approve staff to file this information with the FERC as well as updates that may be created as additional information becomes available. Sample maps are attached. Page 3 of 5 Wetland Delineation: Several citizens have expressed concern that MVP surveyors did not properly identify and mark wetlands and other water features on their property. They are further concerned that if wetland delineation is not done properly, appropriate mitigation steps will not be taken. In a citizen led and funded initiative, additional wetland survey work has been performed by a qualified professional and submitted to the County. If wetland and other water resources are not properly protected during construction, impacts to County citizens could include: well contamination, siltation of streams that are regulated under the County's MS -4 permit, and damage to adjacent property from surface runoff. The Roanoke County Pipeline Advisory Committee and staff recommends that the Board of Supervisors authorize staff to pursue this concern with FERC, the Army Corps of Engineers, the Virginia Department of Environmental Quality and other agencies as appropriate. Depending on the results of additional staff work in the area, further steps may be brought to the Board of Supervisors for consideration. Additional Considerations MVP has filed well over 2,000 pages of materials within the past 6 weeks with its most recent filing being a 730 page document filed on February 29, 2016. This is in addition to tens of thousands of pages of material filed previously with the Federal Energy Regulatory Commission. At the time of its last meeting on February 22, 2016, the most recent project filing was not available to the Pipeline Advisory Committee for review. In addition to the topic areas listed above, the Pipeline Advisory Committee and staff are recommending to the Board in the attached resolution that authorization be given to continue to collaborate and make additional responsive filings with the Federal Energy Regulatory Commission that are consistent with this resolution and past actions of the Board. This will ensure that Roanoke County's comments are submitted in a timely fashion for consideration by the Federal Energy Regulatory Commission. The Board will continue to receive project briefings and be apprised of future policy decision points that the project will likely present along with recommended actions. FISCAL IMPACT: None Page 4 of 5 ALTERNATIVES: 1. Approve the attached resolution 2. Deny the amendment as presented STAFF RECOMMENDATION: Staff recommends alternative 1. 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The purpose of this answer is to respond to certain arguments in Mountain Valley Pipeline, LLC's Answer regarding the appropriateness of programmatic review under the National Environmental Policy Act (NEPA) for pipeline projects that are not necessarily "connected actions" or part of a "federally coordinated plan, and the appropriateness of the Commission analyzing gathering lines as part of either project -specific or programmatic NEPA review. I. MOTION FOR LEAVE TO FILE AN ANSWER Pursuant to 18 C.F.R. § 385213(a)(2), Roanoke County requests the opportunity to be heard on certain arguments made in Mountain Valley Pipeline, LLC's Answer. Rule 213(a)(2) prohibits an answer to an answer unless otherwise ordered by the decisional authority. However, the Commission has granted leave to file such answers if they clarify the issues in dispute, ensure a complete and accurate record, or otherwise provide information that will assist the Commission in its decision-making process_3 18 C.F.R. §§ 385.212, 385.213. Mountain Valley Pipeline, LLC, "Motion to Answer and Answer," eLibrary no. 20160127-5259 (Jan. 27, 2016). j See, e.g., S. La. Elec. Coop. Assoc., 144 FERC ¶ 61,050 (July 18, 2013) (allowing an answer to an answer where "it will assist the Commission in its decision-making process"); Mich. Elec. Transmission Co., 106 FERC ¶ 61,064 (Jan. 28, 2004) (allowing an answer to an answer that "provides information that clarifies the issues"); Dominion Transmission, Inc., 105 FERC ¶ 61173 (Oct. 31, 2003) (waiving Rule 213(a)(2) because the "answer may aid in the disposition of the issues raised by the subject filing"). Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) Given the general rule against answers to answers, the County has not responded to all of the arguments raised by Mountain Valley Pipeline, LLC's Answer. Rather, our answer is limited to information necessary to clarify the disputed issues, correct mischaracterizations, or respond to new arguments raised by Mountain Valley Pipeline, LLC. The County respectfully requests that the Commission consider this limited answer because it will clarify the issues and assist in the Commission's decision-making. II. ANSWER A. Programmatic NEPA Review Is Not Just for the MVP Proiect. Mountain Valley Pipeline, LLC's Answer objects to Roanoke County's comments in support of the Commission's preparation of a Programmatic Environmental Impact Statement (PEIS) for the MVP Project.4 The County noted that there were several other pipeline projects in Western Virginia that were also pending before the Commission, including the Equitrans Expansion, Atlantic Coast Pipeline, and Appalachian Connector Projects. Id. The County submitted that the most efficient way to conduct a comprehensive study of cumulative impacts and need for these and other potential natural gas projects in the region was to prepare a PEIS. Id. In its answer, Mountain Valley Pipeline, LLC argues that preparation of a PEIS for the MVP Project would actually be inefficient.5 It states: "[a]n extended programmatic EIS, however, covering multiple unrelated projects that happen to be planned in the same general region is unnecessary to facilitate the Commission's review of the MVP Project. ,6 The County's interest in the Commission's preparation of a PEIS is broader than just the outcome of the MVP Project. As stated in our previous comments, there are four pipeline projects that have been proposed in this region. This is indicative of an unprecedented increase in natural gas development throughout Greater Appalachia that shows no signs of slowing soon. The County's request is consistent with the Council for Environmental Quality's (CEQ) recommendation that "agencies give particular consideration to preparing a PEA or PEIS when ... making decisions on common elements or aspects of a series or suite of closely related projects."7 As discussed below, CEQ states that programmatic review in of several similar 4 See Roanoke County, Virginia, "Roanoke County's Motion to Intervene and Identification of Issues," eLibrary no. 20151125-5074 (Nov. 25, 2015), p. 6. See Mountain Valley Pipeline, LLC's Answer, p. 27. Id. at 3 (emphasis added). CEQ, Effective Use of Programmatic NEPA Reviews (2014) (CEQ Programmatic NEPA Guidance), p. 15, available at haps://www.whitchouse.gov/administration/eop/ceg/initiatives/nepa/programmatic-reviews. CEQ Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16--10-000) W projects in a particular geographic area can improve the impacts analysis of the multiple projects and increase the efficiency of project -specific NEPA review.8 Mountain Valley Pipeline, LLC's arguments that preparation of a PEIS would be inefficient appear to relate primarily to the potential for delay of the MVP Project timeline. It assumes that the Commission could not proceed with preparation of a project -specific Environmental Impact Statement (EIS) for the MVP Project until it completed a PEIS. However. CEQ's regulations implementing NEPA provide that a lead agency's decision to prepare a programmatic NEPA document does not need to halt or delay any project -specific NEPA review that is already underway.9 CEQ Regulation 1506.1 expressly provides that project -specific NEPA review may proceed simultaneous with the preparation of the broader NEPA programmatic review so long as the project -specific NEPA does not limit the analysis that would be undertaken in the programmatic review. Thus, Mountain Valley Pipeline, LLC's objections that programmatic review would necessarily delay the MVP Project are unfounded, and more importantly, miss the broader purpose programmatic NEPA review of the several pipeline projects in this region. B. Preparation of a PEIS Can Be Appropriate Regardless of Whether "Connected Actions" or a "Federally Coordinated Plan" Are Involved. In its Answer, Mountain Valley Pipeline, LLC argues that the Commission is not required to prepare a PEIS here because the pipeline projects pending before FERC are not "connected actions" or part of a "federally coordinated plan." 10 A finding that "connected actions" are involved or that the actions are part of a "federally coordinated plan" is not necessary to a determination of whether programmatic review should be undertaken. The County maintains that CEQ's regulations and guidance should be read in favor of the Commission exercising its discretion to prepare a PEIS in these circumstances because programmatic NEPA review will streamline project -specific NEPA review and better achieve NEPA's purpose of protecting environmental quality. CEQ regulations and guidance provide that NEPA programmatic review may be appropriate and beneficial when a federal agency is approving similar projects in a particular lists approving "[s]everal similar actions or projects in a region or nationwide" as a programmatic example. Id. at 14. 8 Id. at 10. See also Daniel R. Mandelker, NEPA Law and Litigation (2013), p. 555 ("Often it is difficult to examine the cumulative impact of a number of individual but related actions when they are reviewed one at a time. The program impact statement can help overcome this problem by considering a group of related actions together or by reviewing the implications of an agency's program comprehensively before it produces actions that will be reviewed individually."). 40 C.F.R. § 1506.1. 10 Mountain Valley Pipeline, LLC's Answer, pp. 17-19. Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) geographic area with common environmental impacts." CEQ's, "Effective Use of Programmatic NEPA Review," in particular finds that NEPA programmatic review can be appropriate for "several similar actions or projects in a region" that are "likely to have effects on the same environmental resources" and that enable federal agencies to avoid "repetitive broad level analysis in subsequent tiered NEPA reviews to provide a more comprehensive picture of the consequences of multiple proposed actions." 12 The County disagrees with Mountain Valley Pipeline LLC that the Commission should dismiss this CEQ guidance out -of -hand. 13 CEQ is charged with developing national policies directed to achieving the purposes of NEPA. 14 The Commission's regulations state that it will comply "with the regulations of the [CEQ] except where those regulations are inconsistent with the statutory requirements of the Commission." 15 Under CEQ Regulation 1500.2, federal agencies have an obligation to "[u/se all practicable means, consistent with the requirements of the Act and other essential considerations of national policy, to restore and enhance the quality of the human environment and avoid or minimize any possible adverse effects of their actions upon the quality of the human environment. 16 The U.S. Department of Energy and the U.S. Department of the Interior's Programmatic Environmental Impact Statement on Designation of Energy Corridors on Federal Land in the 11 Western States shows how programmatic review can better protect environmental quality in circumstances like these. 17 The purpose of the energy corridor designation was to streamline agency review and ensure consistency in applications to construct oil and natural gas pipelines in eleven western states. More specifically, it would identify appropriate areas for the siting of oil and natural gas pipelines due to concerns regarding adverse impacts on wildlife, endangered species, water quality, scenic, and cultural/historical resources. This information could then be "used to tier to site-specific environmental reviews."18 According to the lead agencies, "[b]y 11 40 C.F.R. § 1502.4(c); see also CEQ, "Forty Most Asked Questions Concerning CEQ's National Environmental Policy Act Regulations," 46 Fed. Reg. 18026 (1981), Answer 24b. 12 CEQ Programmatic NEPA Guidance, p. 12. 13 See Mountain Valley Pipeline LLC's Answer, p. 20 ("CEQ Guidance, by its very nature, is non-binding and not legally enforceable'). 14 42 U.S.C. § 4344. 15 18 C.F.R. § 380.1. 16 40 C.F.R. § 1500.2(f) (emphasis added). "The phrase `to the fullest extent possible' ... means that each agency of the Federal Government shall comply with that section unless existing law applicable to the agency's operations expressly prohibits or makes compliance impossible." 40 C.F.R. § 1500.6. 17 DOE/EIS-0386, available at hlt2:Hcorridoreis.anl.gov/eis/guide/index.cfm#vol1. 18 Id., p. S-6. Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) il analyzing and presenting project -related impacts from future actions, the PEIS provides invaluable information for future site-specific environmental reviews." 19 The rationale provided for the Western Energy Corridors PSIS was not that the designated oil and natural gas pipeline corridor or exclusion areas constituted connected actions, or that the individual oil and gas pipeline projects proposed in the several states constituted connected actions under NEPA. Rather, the rationale was that environmental review of site- specific oil and natural gas pipeline projects that tiered off of the Western Energy Corridors PSIS would be streamlined and likely result in better planning and a reduction in the proliferation of pipeline ROWS across the landscape in the region (by concentrating additional pipelines in pre -designated corridors).20 That rationale is equally applicable here. Mountain Valley Pipeline, LLC also argues that the MVP Project will serve different markets and is "miles apart" from the other pipeline projects cited by the County.21 The fact that the MVP Project will serve different markets does not make the environmental impacts of the project dissimilar from the other proposed projects. Further, the descriptions of the several projects clearly show that they will occur in the same geographic region. For example, information provided for the Appalachian Connector Project show that it will pass through Roanoke County.22 Programmatic review for these projects would avoid redundant, duplicative or potentially inconsistent analysis in later tiered project -specific NEPA review of such issues as baseline/background conditions, cumulative impacts analysis, and identification and analysis of direct/indirect effects. Similar to the Western Energy Corridors PSIS, programmatic review here could reduce the proliferation of ROWS across the regional landscape. This type of tiering and broad regional analysis would be of benefit to the Commission, cooperating agencies like the U.S. Forest Service, pipeline applicants, and other stakeholders regardless of whether the scope of actions considered in the PEIS were "connected actions" undertaken pursuant to a "federally coordinated plan." 19 Id., p. S-11. 20 The Western Energy Corridors PEIS found that the proposed action to designate energy corridors would be environmentally superior to the no action alternative: Under the No Action Alternative ... there would be no assurance of consistency in siting or evaluation of proposed energy transport projects crossing federal lands. Id, p. S-17. By contrast, "[c]orridor designation would likely reduce the proliferation of ROWS across the landscape, and concentrate development to some extent within the corridors ... [and would provide] both streamlined administrative procedures and best practices for environmental compliance and protection." Id, p. S-25. 21 Mountain Valley Pipeline, LLCs Answer, p. 20. 22 See Williams, "Appalachian Connector," hlt2:Hco.williams.com/expansionprojects/appalachian-connector/; Aaron Martin, "31 Natural Gas Pipeline Could Run through Southern Virginia," available at hilp://wsls.com/2014/10/31 /3rd-natural-gas-pipeline-could-run-through-southern-virginia/. Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) 5 C. Information on and Analysis of Gathering Lines Related to the MVP Proiect Is Required in the Proiect-Specific EIS for the MVP Proiect Regardless of Whether a PEIS is Prepared. Mountain Valley Pipeline, LLC has suggested that while a PEIS would address natural gas gathering lines in the region, such analysis of gathering lines would not need to be included in the project -specific NEPA review of the MVP Project .23 This is incorrect. Even for project - specific NEPA review, NEPA statutory provisions and CEQ regulations require the lead agency to set forth an accurate and complete description of background/baseline conditions, identify and analyze projects in the region with similar cumulative environmental impacts, and identify and analyze direct and indirect environmental effects resulting from the proposed project. All of these requirements implicate gathering lines in the context of project -specific NEPA review of the MVP Project. The existence of gathering lines in the region where the MVP Project is to be located constitutes part of the background/baseline conditions against which the MVP Project will operate. The project specific impacts of the MVP Project need to be considered in the cumulative context of other past, present and reasonably anticipated natural gas pipelines in the region, including existing and proposed natural gas gathering lines. Finally, if it is foreseeable that the construction of the MVP Project will result in the construction of additional gathering lines to transport natural gas from the wellheads to the MVP Project, then these anticipated additional gathering lines need to be analyzed in the project - specific EIS as direct/indirect effects. While analysis of gathering lines needs to be included in the project -specific NEPA review of the MVP Project, gathering lines also provide an excellent example of the type of background conditions, cumulative impacts and direct/indirect impacts that could be more efficiently and uniformly analyzed (and later tiered off of) in the context of a PEIS. III. CONCLUSION Roanoke County requests that the Commission grant its Motion for Leave to File an Answer, and consider its Answer, which bears both on whether the Commission should proceed with preparation of programmatic NEPA review, and how the question of natural gas gathering lines should be addressed in the current project -specific EIS for the MVP Project. Dated: March 2, 2016 Respectfully submitted, 23 Mountain Valley Pipeline, LLC's Answer, pp. 28-30. Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) no 144..4 5�e�ot�� Paul S. Kibel Julie Gantenbein WATER AND POWER LAW GROUP PC 2140 Shattuck Ave., Ste. 801 Berkeley, CA 94708 (510) 296-5588 pskibel2waterpowerlaw. com i gantenbein(c�r�,waterpowerlaw.com Attorneys for ROANOKE COUNTY, VIRGINIA Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) DECLARATION OF SERVICE Mountain Valley Pipeline, LLC's Mountain Valley Pipeline Proiect (CP16-10-000) I, Julie Gantenbein, declare that I today served the attached "Motion for Leave to File an Answer and Answer of Roanoke County, Virginia" by electronic mail, or by first-class mail if no e-mail address is provided, to each person on the official service list compiled by the Secretary in this proceeding. Dated: March 2, 2016 Un Roanoke County's Motion to Answer and Answer Mountain Valley Pipeline Project (CP16-10-000) Julie Gantenbein WATER AND POWER LAW GROUP PC 2140 Shattuck Ave., Suite 801 Berkeley, CA 94704-1229 Phone: 510- 296-5590 Fax: 866-407-8073 J gantenbeingwaterpowerlaw.com N. I Mountain Valley Pipeline Final Route With Slope (Percent Rise) Slope Percent Rise 8%-25% Percent Rise Acres Percent N Percent 26%-40% <-7 63.4 15% tl°d,nem°aa=na9etleee"lea,ed9oR°°5 <= 25 143.2 39% 0% - 7% >40% <_ ° dtthe.7 21 /o 0.5 0.25 0 0.5 >40 79.6 25% dorataotia.,a st,,I, �2aatnadaI t Mile Markers he nme� Total 353.9 100% ��adh, I'vIdFati,�ry,a,zloun,.Ia ���o� Mountain Valley Pipeline Final Route With Soil Erosion Hazard Soils Erosion Hazard - Slight (7%) Erosion Hazard Acres Percent N Not Rated 0.22 0% sood,n�,nadntI%" ad,n,o Rating Moderate (9%) Slight 26.04 7% �aa°d`r�a�a=haatiaa"=�aa�ad`��`R� 9o�a,�ma��a�da,tia�a��,�a=a� Notrated0% S 84% Moderate 31.6 9% as"o�avo7na rated(0%) Severe ( ) 0.5 0.25 0 0.5 Severe 296 84% the Mile Mile Markers Total 353.9 100% nm�e� "°°°`a°tiv ��ry�a,=o�s°""°'a ""�°" AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION APPROVING RECOMMENDATIONS FROM THE PIPELINE ADVISORY COMMITTEE FOR FILING WITH THE FEDERAL ENERGY REGULATORY COMMISSION REGARDING THE MOUNTAIN VALLEY PIPELINE PROJECT WHEREAS, on November 10, 2016, the Roanoke County Board of Supervisors authorized County staff to file the necessary motion to intervene with the Federal Energy Regulatory Commission in the Mountain Valley Pipeline proceedings; and WHEREAS, on December 24, 2015, the Federal Energy Regulatory Commission made a formal request to Mountain Valley Pipeline seeking additional information regarding hundreds of issues, an number of which were raised by Roanoke County; and WHEREAS, on January 15 2016, January 27, 2016, and February 29, 2016, Mountain Valley Pipeline (MVP) has filed a total of over two thousand (2,000) pages of materials with the Federal Energy Regulatory Commission in response to its questions; and WHEREAS, on January 27, 2016, MVP filed a "Motion to Answer and Answers" with the Federal Energy Regulatory Commission which, in part, addressed specific items from Roanoke County's Motion of Intervention; and WHEREAS, the Roanoke County Pipeline Advisory Committee met on February 8, 2016 and February 22, 2016, to initiate its review of Mountain Valley Pipeline's filings with the Federal Energy Regulatory Commission; NOW, THEREFORE, BE IT RESOLVED by the Board of Supervisors of the County of Roanoke, that the Board of Supervisors accepts the recommendations of the Page 1 of 2 Pipeline Advisory Committee as presented on March 8, 2016, and directs staff to take the following actions: 1) File with the Federal Energy Regulatory Commission the "Motion for leave to file an answer and limited answer of Roanoke County, Virginia" as prepared by outside counsel which addresses specific issues raised by Roanoke County in its Motion of Intervention; 2) File with the Federal Energy Regulatory Commission additional comments regarding the proposed crossings of the Roanoke River and impacts to the Roanoke watershed; additional information and concerns regarding how Mountain Valley Pipeline has failed to address issues related to steep slope construction and highly erodible soils; and concerns related to wetland delineation; 3) To work and collaborate with the Pipeline Advisory Committee to create and make additional filings with the Federal Energy Regulatory Commission supporting past Board actions and direction as review of recent Mountain Valley Pipeline materials are completed. Page 2 of 2 ACTION NO. ITEM NO. E-2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: SUBMITTED BY: APPROVED BY: Resolution requesting changes in the Virginia Department of Transportation Primary and Secondary System of State Highways, Route 221, Bent Mountain Road; Route 688, Cotton Hill Road; Route 745, Ran Lynn Drive; Route 957, Sunnycrest Loop, Cave Spring and Windsor Hills Magisterial District David Holladay Planning Administrator Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: The Virginia Department of Transportation (VDOT) has completed Project 0221-080- 108, C-502, the Route 221 Widening Project. A resolution from the Roanoke County Board of Supervisors is needed to request VDOT to abandon the old road facilities which no longer serve the public need, add new road facilities to the secondary system of state highways, and make adjustments to the primary system of highways. A project sketch is attached showing all the proposed changes. VDOT form AM -4.3 is also attached and reports the changes in the secondary system. FISCAL IMPACT: None STAFF RECOMMENDATION: Staff recommends that the Board approve a resolution to request VDOT to abandon sections of Cotton Hill Road and Ran Lynn Drive; transfer sections of Bent Mountain Road to Sunnycrest Loop, add new sections of Cotton Hill Road and Ran Lynn Drive, and make necessary data corrections, abandonments and additions to Bent Mountain Road. Page 1 of 1 M N y •--� Vr M O1 O O O O O •--� l� O� N N O1 O � ra O O O O M ,-- --� •--� N --� O --� O O O � --� O O O O O O O O O O O O O O O O O O H i ''6 i ^' � N z � .moi % % R � O D � � �❑ .yNN�0V/OOUcn�Wd a Y N o 3' 27 11, Nb LL C ldNNxHoQWnbyyOaJi O O W a Nm b JUti.�O J~ d�NNF=W .1�❑xO'"=-oNNHNNY/OOU cccccc �jJ �� � 'O'0�c v �-�- �J W � W [i li.i W WF WF '� WF fiF W fi w W WF WF �OO'0ovi�y y; y 00 r- N ■�I oN terV ”= "� LL 0Oa'�Qs'H�/-OONNNN ^U co ��dLy�/-�OFSNNNN . y� yU� �O���"qdNNoV -pzoa ai W to N 11 11 UZILL TU ONNd bbN Q�y�Ua0.Z , LO a`3 o Z co N��RQao=„oaaoa Q U� In O��,�(ooDOf. - �R__— a��y 00 m �ary_- EWc N'' O,//r 4pOJ1L - CILO i ,, .•`� NN •�_O�ac�cpi�o��VIWr� N00 p ,b�CQ�yoo�3a, 0 �'+�o���oU1 •U L V ph � a � I.fi R W � W [i li.i W WF WF '� WF fiF W fi w W WF WF In the County of Roanoke ----------------------------------------------------------------------------------------------------------------- By resolution of the governing body adopted March 8, 2016 The following VDOT Form AM -4.3 is hereby attached and incorporated as part of the governing body's resolution for changes in the secondary system of state highways. A Copy Testee Signed (County Official).- Report fficial): Report of Changes in the Secondary System of State Highways Project/Subdivision 0221-080-108, C-502 Type Change to the Secondary System of State Highways: Abandonment The following facilities of the Secondary System of State Highways are hereby ordered abandoned, pursuant to the statutory authority cited: Reason for Change: Abandonment, VDOT Project Related Pursuant to Code of Virginia Statute: §33.2-912 Street Name and/or Route Number ♦ Ran Lynn Drive, State Route Number 745 Old Route Number: 0 --—————————————————————————————————————————- • From: Old Int. Rt 221 (D) To: 0.07 MI N Old Int. Rt. 221 (0), a distance of: 0.07 miles. Street Name and/or Route Number ♦ Cotton Hill Road, State Route Number 688 Old Route Number: 0 --—————————————————————————————————————————- • From: Old Int. 221 (C) To: 0.10 MI S Old Int. Rt. 221 (M), a distance of: 0.10 miles. VDOT Form AM -4.3 (4/20/2007) Maintenance Division Date of Resolution: March 8, 2016 Page 1 of 3 Report of Changes in the Secondary System of State Highways Project/Subdivision 0221-080-108, C-502 Type Change to the Secondary System of State Highways: Transfer This Board hereby requests the transfer of the following segment(s) of the Interstate or Primary System to this County's secondary system of state highways. Reason for Change: Primary to Secondary System Transfer Pursuant to Code of Virginia Statute: §33.2-315 Street Name and/or Route Number ♦ Sunnycrest Loop, State Route Number 957 Old Route Number: 221 --—————————————————————————————————————————- • From: End Cul-de-sac (R) To: Int. Rt 221 (S), a distance of: 0.15 miles. Street Name and/or Route Number ♦ Sunnycrest Loop, State Route Number 957 Old Route Number: 221 --—————————————————————————————————————————- • From: 0.09 MI W Old Int. Rt. 725 (Q) To: End Cul-de-sac (R), a distance of: 0.09 miles. VDOT Form AM -4.3 (4/20/2007) Maintenance Division Date of Resolution: Page 2 of 3 Report of Changes in the Secondary System of State Highways Project/Subdivision 0221-080-108, C-502 Type Change to the Secondary System of State Highways: Addition The following additions to the Secondary System of State Highways, pursuant to the statutory provision or provisions cited, are hereby requested; the right of way for which, including additional easements for cuts, fills and drainage, as required, is hereby guaranteed: Reason for Change: VDOT Project Pursuant to Code of Virginia Statute: §33.2-705 Street Name and/or Route Number ♦ Cotton Hill Road, State Route Number 688 Old Route Number: 0 --—————————————————————————————————————————- • From: New Int. Rt. 221 (B) To: 0.10 MI S New Int. Rt. 221 (M), a distance of: 0.10 miles. Recordation Reference: N/A Right of Way width (feet) = 0 Street Name and/or Route Number ♦ Sunnycrest Loop, State Route Number 957 Old Route Number: 0 --—————————————————————————————————————————- • From: 0.09 MI E Old Int. Rt. 745 (F) To: 0.09 MI W Old Int. Rt. 725 (Q), a distance of: 0.02 miles. Recordation Reference: N/A Right of Way width (feet) = 0 Street Name and/or Route Number ♦ Ran Lynn Drive, State Route Number 745 Old Route Number: 0 --—————————————————————————————————————————- • From: New Int. Rt. 221 (B) To: 0.11 MI N New Int. Rt. 221 (0), a distance of: 0.11 miles. Recordation Reference: N/A Right of Way width (feet) = 0 VDOT Form AM -4.3 (4/20/2007) Maintenance Division Date of Resolution: Page 3 of 3 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON MARCH 8, 2016 RESOLUTION REQUESTING CHANGES IN THE VIRGINIA DEPARTMENT OF TRANSPORTATION PRIMARY AND SECONDARY SYSTEM OF STATE HIGHWAYS, ROUTE 221, BENT MOUNTAIN ROAD; ROUTE 688, COTTON HILL ROAD; ROUTE 745, RAN LYNN DRIVE; ROUTE 957, SUNNYCREST LOOP, CAVE SPRING AND WINDSOR HILLS MAGISTERIAL DISTRICT WHEREAS, the Virginia Department of Transportation has completed Project 0221-080-108, C-502, the Route 221 Widening Project; and WHEREAS, the project sketch and VDOT Form AM -4.3, attached and incorporated herein as part of this resolution, defines adjustments necessary in the Primary and Secondary Systems of State Highways as a result of Project 0221-080- 108, C-502; and WHEREAS, certain segments identified in the incorporated Form AM -4.3 appear to no longer serve public convenience and should be abandoned as part of the Secondary System of State Highways; and WHEREAS, certain segments identified in the incorporated Form AM -4.3 are ready to be accepted into the Secondary System of State Highways; and WHEREAS, certain segments identified in the incorporated Form AM -4.3 are ready to be transferred from the Primary System of State Highways to the Secondary System of State Highways. NOW, THEREFORE, BE IT RESOLVED: 1. The Board of Supervisors hereby requests the Virginia Department of Transportation to take the necessary action to abandon those segments identified on the attached project sketch and Form AM -4.3 as part of the Page 1 of 2 Secondary System of State Highways, pursuant to §33.2-912, Code of Virginia, and 2. The Board of Supervisors requests the Virginia Department of Transportation to add the segments identified on the attached project sketch and Form AM - 4.3 to the Secondary System of State Highways, pursuant to §33.2-705, Code of Virginia, and 3. The Board of Supervisors requests the Virginia Department of Transportation to take the necessary action to transfer the segments identified on the attached project sketch and Form AM -4.3 from the Primary System of State Highways to the Secondary System of State Highways, pursuant to §33.2- 315, Code of Virginia, and 4. The Board of Supervisors requests the Virginia Department of Transportation take the necessary action to abandon those segments identified on the attached project sketch as part of the Primary System of State Highways, pursuant to §33.2-906, Code of Virginia, and 5. A certified copy of this resolution be forwarded to the VDOT Salem Residency, by the Clerk to the Board of Supervisors. Page 2 of 2 ACTION NO. ITEM NO. E-3 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Resolution adopting revisions to the Stormwater Management Design Manual SUBMITTED BY: Arnold Covey Director of Development Services APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: Roanoke County currently has a Stormwater Management Design Manual that supplements the adopted new stormwater management ordinance. The purpose of the manual is to assist engineers and developers to prepare development plans that meet County/State requirements and assist the County in implementing its post -construction responsibilities (periodic inspection). Generally all chapters have: • Updated references to current manuals • Spelling/grammar corrections • Acronyms and units revised to correct nomenclature Many chapters have numerous minor changes in technical or procedural requirements in response to our experience over the past year running the County's Virginia Stormwater Management Program (VSMP). Page 1 of 3 Following are some of the more significant proposed changes: • Require additional information for development with wetlands • Submittal of stormwater master plan for phased plans in a common plan development • Additional information for stormwater plans to improve review efficiency and recordkeeping • Add section on residential lot grading and drainage • Expand the requirements for as -built (record) drawings County staff has reviewed these changes with the Roanoke Regional Home Builders Association (RRHBA) and with the Board of Supervisors at a work session on August 25, 2015. Following the September 22, 2015 Board meeting, the staff met several times with the Roanoke Regional Home Builders Association (RRHBA) and together resolved all outstanding issues. Since the January 26, 2016 Board work session, it has been brought to staff's attention there are some minor clarifications that need to be addressed. The following are revisions that have been made to the Stormwater Design Manual. • Section 1.7.1 was revised to 3 feet instead of 2 feet to reflect the current change to the State's Building Code when a building permit is required for a retaining walls. • Section 5.2.7E was revised to clarify that yard swales must have a grass liner due to a missing word in the previous version of the manual. • Section 7.2.6 B —revised to provide clarity that the maximum pipe velocity is based on the 10 year storm. • Section 7.2.9 B — revised to clarify that 2 feet of cover is required for pipes. Pipes not meeting the cover requirements may be approved by staff based upon site conditions. • Section 15.1.4 —revised to provide additional clarification for CAD drawings layer requirements that are provided for County's GIS. The attached resolution includes all updates and corrections as discussed. FISCAL IMPACT: None ALTERNATIVES: 1. Approve the attached resolution amending the Stormwater Management Design Manual 2. Deny the amendment as presented Page 2 of 3 STAFF RECOMMENDATION: Staff recommends alternative 1. Attachment: Stormwater Management Design Manual Proposed Changes Page 3 of 3 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION ADOPTING REVISIONS TO THE STORMWATER MANAGEMENT DESIGN MANUAL FOR ROANOKE COUNTY WHEREAS, Section 23-1.8 of the Roanoke County Code provides for the adoption of a Stormwater Management Design Manual; and WHEREAS, Roanoke County will utilize the policies, criteria, and information contained in this design manual for the proper implementation and requirements of the stormwater management ordinance; and WHEREAS, this design manual shall be authorized and approved by the Board of Supervisors by resolution. NOW, THEREFORE BE IT RESOLVED, by the Board of Supervisors of Roanoke County, Virginia, as follows: 1. That the Stormwater Management Design Manual dated September 22, 2015 and approved by the Board of Supervisors by Resolution on September 22, 2015, is hereby repealed. 2. That the "Stormwater Management Design Manual" dated March 8, 2016 is hereby adopted in order to implement the requirements of Chapter 23. "Stormwater Management Ordinance", as provided in Section 23-1.8. 3. That this resolution shall be effective from and after March 8, 2016. Page 1 of 1 COUNTY OF ROANOKE STORMWATER MANAGEMENT DESIGN MANUAL �.�n �»X 1, 2016 ALLY!,TT Department of Community Development 5204 Bernard Drive Roanoke, Virginia 24018 r,rLY 1,204-4x 1, 2016 TABLE OF CONTENTS COUNTY OF ROANOKE STORMWATER MANAGEMENT DESIGN MANUAL IWNDIW.Ty01 Roanoke County's intent is to comply with the state Stormwater Management Law and Regulations, through implementation of the Roanoke County Stormwater Management Ordinance. All BMPs proposed for use in the County must be previously approved by DEQ and they must be contained on the VA BMP Clearinghouse. This Design Manual has local requirements that aid in the implementing of the state requirements and that supplement the state requirements. This ML X42016 edition of the Design Manual replaces the Septa .43er- 11, 2007July 1, - - Formatted: Highlight 2014 Design Manual, as approved by the Board of Supervisors by Resolution Formatted: Highlight oat'^. Due to the complexity of the subject, it is necessary for engineers and designers to be familiar with the information contained in all of the references listed in Section 1.8 of this manual. COUNTY OF ROANOKE i TABLE OF CONTENTS q444X/1/16- TABLE OF CONTENTS (Chapter 1— Introduction 1.1 Manual Purpose...............................................................................................1-1 1.2 Water Programs Regulatory Background......................................................1-1 2.3 1.2.1 Erosion and Sediment Control Program.................................................1-2 2.34 1.2.2 Stormwater Management Program.........................................................1-2 2.45 1.2.3 Floodplain Management Program........................................................... 1-2 2.56 1.2.4 Illicit Discharge Detection and Elimination Program.............................1-2 1.2.5 Municipal Separate Storm Sewer System (MS4) Permit ........................1-2 1.3 Contents of the Manual....................................................................................1-3 1.4 Authority...........................................................................................................1-4 1.5 Applicability.....................................................................................................1-4 1.6 Administration..................................................................................................1-4 1.6.1 General...................................................................................................1-4 1.6.2 Manual Amendments..............................................................................1-5 1.6.3 Exceptions..............................................................................................1-5 1.6.4 Appeal of Decisions...............................................................................1-5 1.7 Approval and Permits......................................................................................1-5 1.7.1 Local Approvals and Permits..................................................................1-5 1.7.2 Water and Sewer Approvals and Permits ................................................ 1-5 1.7.3 Joint Permit Application ...................................... .................... ............. 1-6 1.8 Reference Sources............................................................................................1-6 1.8.1 County of Roanoke Code and Ordinances .............................................. 1-6 1.8.2 Virginia Law and Regulations................................................................1-7 1.8.3 Virginia Manuals, Handbooks and Websites .......................................... 1-7 1.9 Acronyms and Abbreviations..........................................................................1-7 Appendix 1A — Roanoke County Policy on Common Plan of Development or Sale Chapter 2 Stormwater Management Plan Review and Approval 2.1 Overview of the Review and Approval Process..............................................2-1 2.2 Concept Stormwater Management Plan Submittal.......................................2-1 2.3 Stormwater Management Master Plan Submittal.........................................2-1 2.34 Stormwater Management Plan Submittal......................................................2-1 2.45 Submittal of Stormwater Calculations...........................................................2-2 2.56 Changes and Modifications to an Approved Plan..........................................2-3 Chapter 3 Easements 3.1 General..............................................................................................................3-1 3.2 Drainage Easements.........................................................................................3-1 3.2.1 Culverts and Storm Drains...................................................................... 3-2 3.2.2 Open Channels....................................................................................... 3-3 3.3 Access Easements.............................................................................................3-4 3.4 Maintenance of Easements.............................................................................. 34 - - Commented [AG1]: This page will need to be updated once all revisions have been made. COUNTY OF ROANOKE ii TABLE OF CONTENTS q444X/1/16- TABLE OF CONTENTS Appendix 3A — Standard Easement Agreements (Chapter 4 Stormwater Hydrology 4.1 References.........................................................................................................4-1 5.2.1 Major and Minor Channels..................................................................... 4.2 Design Frequencies...........................................................................................4-1 5-1 5.2.3 Hydrology.............................................................................................. 4.2.1 General...................................................................................................4-1 5.2.4 Channel Hydraulics................................................................................ 5-2 4.2.2 Storm Drainage Systems........................................................................4-1 5.2.6 Channel Slope........................................................................................ 4.2.3 Stormwater Management Facilities........................................................4-2 5.2.7 Cross Sectional Area.............................................................................. 4.3 Time of Concentration (t�) and Travel Time(Tt)...........................................4-2 5-5 5.2.9 Freeboard Requirements......................................................................... 4.3.1 General...................................................................................................4-2 5.2.10 Calculation of Depth of Flow at Bends and Curves ................................ 5-7 4.3.2 Overland Flow........................................................................................4-2 5-7 5.3 Environmental Considerations and Fishery Protection ................................ 4.3.3 Shallow Concentrated Flow....................................................................4-3 5.5 Maintenance Requirements............................................................................. 5-8 4.3.4 Channelized Flow...................................................................................4-3 4.3.5 Pipe Flow...............................................................................................4-3 4.4 Selection of Methodologies...............................................................................4-3 4.4.1 General...................................................................................................4-3 4.4.2 Peak Discharge Methods for Design of Storm Drainage Systems ..........4-4 4.4.3 Hydrograph Methods for Design of Stormwater Management Facilities 4-4 4.5 Methodologies...................................................................................................4-4 4.5.1 Rational Method.....................................................................................4-4 4.5.2 Modified Rational Method.....................................................................4-6 4.5.3 SCS Method...........................................................................................4-7 Appendix 4A — Design Aids, From Chapter 6, VDOT Drainage Manual Appendix 4B — Design Aids, From Chapter 4, VA SWM Handbook Appendix 4C — Information from VDOT Hydraulic Design Advisories Chapter 5 Open Channels 5.1 References.........................................................................................................5-1 5.2 Design Methodology and Criteria...................................................................5-1 5.2.1 Major and Minor Channels..................................................................... 5-1 5.2.2 Design Flow........................................................................................... 5-1 5.2.3 Hydrology.............................................................................................. 5-1 5.2.4 Channel Hydraulics................................................................................ 5-2 5.2.5 Channel Velocity....................................................................................5-2 5.2.6 Channel Slope........................................................................................ 5-3 5.2.7 Cross Sectional Area.............................................................................. 5-4 5.2.8 Channel Lining....................................................................................... 5-5 5.2.9 Freeboard Requirements......................................................................... 5-6 5.2.10 Calculation of Depth of Flow at Bends and Curves ................................ 5-7 5.2.11 Channel Location and Width Restrictions on Residential Lots ............... 5-7 5.3 Environmental Considerations and Fishery Protection ................................ 5-8 5.5 Maintenance Requirements............................................................................. 5-8 COUNTY OF ROANOKE iii TABLE OF CONTENTS q444X/1/16- TABLE OF CONTENTS 5.6 Floodplain Studies............................................................................................5-8 Appendix 5A — Aids for Open Channel Design, From Chapter 7, VDOT Drainage Manual_ , - Commented [AGz]: Revise COUNTY OF ROANOKE iv TABLE OF CONTENTS q444X/1/16- TABLE OF CONTENTS Chapter 6 Culverts 6.1 References.........................................................................................................6-1 6.2 Design Methodology and Criteria...................................................................6-2 6.2.1 Computation Methods............................................................................ 6-2 6.2.2 Hydrology.............................................................................................. 6-2 6.2.3 Culvert Hydraulics.................................................................................. 6-2 6.2.4 Structural Design....................................................................................6-5 7-2 6.2.5 Materials.................................................................................................6-6 7-3 6.2.6 Culvert Sizes.......................................................................................... 6-7 6.2.7 End Conditions.......................................................................................6-7 7-7 6.2.8 Multiple Barrel Culverts.........................................................................6-8 6.2.9 Culvert Skew..........................................................................................6-8 6.2.10 Buoyancy................................................................................................6-8 7.3 6.2.11 Debris and Trash Racks..........................................................................6-9 7-10 6.3 Installation........................................................................................................ 6-9 6.3.1 Bedding Material.................................................................................... 6-9 6.3.2 Backfill...................................................................................................6-9 7-11 6.4 Environmental Considerations and Fishery Protection ................................ 6-9 6.5 Maintenance Requirements........................................................................... 6-10 Appendix 6A — Aids for Stormwater Culvert Design, From Chapter 8, VDOT Drainage Manual Chapter 7 Storm Drains 7.1 References.........................................................................................................7-1 7.2 Design Methodology and Criteria...................................................................7-1 7.2.1 Computation Methods............................................................................ 7-1 7.2.2 Hydrology.............................................................................................. 7-2 7.2.3 Design Flows..........................................................................................7-2 7.2.4 Measures to Convey Stormwater Runoff to Inlets .................................. 7-2 7.2.5 Storm Drain Inlets.................................................................................. 7-3 7.2.6 Storm Drain Pipes.................................................................................. 7-5 7.2.7 Determination of Hydraulic Grade Line ................................................. 7-7 7.2.8 100 -Year Conditions............................................................................7-10 7.2.9 Materials...............................................................................................7-10 7.2.10 Structural Design..................................................................................7-10 7.3 Installation...................................................................................................... 7-10 7.3.1 Bedding Material..................................................................................7-11 7.3.2 Backfill.................................................................................................7-11 7.3.3 Separation of Utilities........................................................................... 7-11 7.4 Environmental Impacts................................................................................. 7-11 7.5 Erosion Protection at Outfalls.......................................................................7-11 7.6 Maintenance Requirements...........................................................................7-11 COUNTY OF ROANOKE v TABLE OF CONTENTS q444X/1/16- TABLE OF CONTENTS Appendix 7A — Aids for Storm Drain System Design, From Chapter 9, VDOT Drainage Manual Appendix 7B — Installation Procedures Chapter 8 Residential Lot Drainage 8.1 References.........................................................................................................8-1 8.2 General Lot Grading ........ ................................................................................ 8-1 8.3 Construction Plan Reguirments......................................................................8-1 Chapter 9 (NOT USED) Chapter 10 Energy Dissipation 10.1 References.......................................................................................................10-1 10.2 Design Methodology and Criteria.................................................................10-2 10.2.1 Outlet Velocity..................................................................................... 10-2 10.2.2 Erosion Control Stone..........................................................................10-2 10.2.3 Riprap Outlet Basins............................................................................. 10-2 10.2.4 Baffled Outlets.....................................................................................10-3 10.2.5 Energy Dissipator for Paved Areas ....................................................... 10-4 10.2.6 Additional Energy Dissipators.............................................................. 10-4 10.3 Installation Requirements..............................................................................10-5 10.4 Easements.......................................................................................................10-5 10.5 Environmental Impacts.................................................................................10-5 10.6 Maintenance Requirements...........................................................................10-5 Appendix 10A — Aids for Energy Dissipation Design, From VDOT Drainage Manual Appendix 10B — Aids for Energy Dissipation Design, From VDOT Road and Bridge Standards Appendix 10C — Energy Dissipation Design Schematics Chapter It (NOT USED) Chapter 12 Environmentally Sensitive Areas 12.1 References.......................................................................................................12-1 12.2 Floodplains......................................................................................................12-2 12.2.1 Applicant Flood Study Requirements................................................... 12-3 12.2.2 Floodplain Delineation.........................................................................12-5 12.3 Steep Slopes....................................................................................................12-5 12.3.1 Development Restrictions..................................................................... 12-5 12.3.2 Design Standards.................................................................................. 12-5 12.4 Stream Buffers................................................................................................12-6 12.5 Critical Erosion Areas....................................................................................12-6 COUNTY OF ROANOKE vi TABLE OF CONTENTS q444X/1/16- TABLE OF CONTENTS 12.6 Karst Geology.................................................................................................12-7 12.7 Stormwater Hot Spots....................................................................................12-8 12.7.1 Design Restrictions............................................................................... 12-9 12.7.2 Golf Course Development....................................................................12-9 Appendix 12A — Design Aids, From Local Assistance Manual, Chesapeake Bay Local Assistance Department Chapter 13 Geotechnical Studies (RESERVED) Chapter 14 Maintenance of Stormwater Management Facilities 14.1 Responsibility for Maintenance.....................................................................14-1 14.2 Maintenance Agreements..............................................................................14-1 14.3 Maintenance Program...................................................................................14-2 14.4 Additional Maintenance and Repair.............................................................14-5 14.5 Inspection and Maintenance Records...........................................................14-5 14.6 References.......................................................................................................14-5 Appendix 14A — Maintenance Agreements Appendix 14B — Maintaining Stormwater Systems, A Guidebook for Private Owners and Operators in Northern Virginia Chapter 15 Inspection and Enforcement 15.1 Construction Inspections...............................................................................15-1 15. 1.1 Notifications to the County of Roanoke...............................................15-1 15.1.2 Periodic Inspections.............................................................................. 15-2 15.1.3 Final Inspection and As -Built Documentation......................................15-2 15.2 Post -Construction Inspections and Maintenance.........................................15-3 15.3 Records...........................................................................................................15-4 15.4 Enforcement...................................................................................................15-4 15.4.1 Notice of Violation...............................................................................15-4 15.4.2 Stop Work Orders................................................................................. 15-5 15.4.3 Restoration of Land.............................................................................. 15-5 Appendix 15A — Inspection Forms , - Commented [AG3]: Revise COUNTY OF ROANOKE vii TABLE OF CONTENTS q444X/1/16- Chapter 1 - Introduction 1.1 Manual Purpose As land is developed and woodlands and pastures are converted to more intensive commercial and residential uses, the increase in impervious surfaces (pavements -+1+4, buildings etc_ and managed turf, cause adverse effects including: , - Formatted: Highlight • Increased flooding • Increased erosion and deposition of sediment in streams • Less base flow in streams due to less groundwater recharge • Increased runoff of pollutants (nutrients, sediment, bacteria, oil) • Decreased stream biodiversity (e.g.,aquatic insects and fish) • Loss of recreational uses such as swimming and fishing The County of Roanoke stormwater management goals are to minimize these adverse effects of land development by implementing effective stormwater management Best Management Practices (BMPs) as required by the County Code for new and redevelopment, and over , - I Formatted: Highlight time, by providing BMP measures to mitigate the adverse effects of past land development activities. The County of Roanoke Stormwater Management Design Manual, hereafter called the Design Manual, contains local requirements that supplement local ordinances, state regulations and guidance, and federal regulations. In general, D eet* direction and guidance from these sources is not repeated in this Design Manual. Refer to the listing of Reference Sources at the end of this chapter. 1.2 Water Programs Regulatory Background The County of Roanoke implements, and is regulated by, several water programs as briefly described below. Land Disturbing Activities are regulated under the erosion and sediment control, stormwater management, and floodplain management programs. Existing Development is regulated by the illicit discharge detection and elimination program and, if the property contains a permanent BMP, by the stormwater management program. The County of Roanoke itself is regulated by the MS4 Permit program. While the MS4 permit only directly regulates the County, it may indirectly impact anyone living in, owning property, or developing in the County of Roanoke through the impact of County actions that are required by its permit. COUNTY OF ROANOKE 7444X/1/16 1-1 INTRODUCTION 1.2.1 Erosion and Sediment Control Program The County is the local Erosion and Sediment Control (E&SC) authority. E&SC requirements are contained in the County of Roanoke Erosion and Sediment Control Ordinance and Virginia Erosion and Sediment Control Regulations. The County administers the program under the oversight of the Virginia Department of Environmental Quality (DEQ). 1.2.2 Stormwater Management Program The County is the local Virginia Stormwater Management Program (VSMP) authority. VSMP requirements are contained in the County of Roanoke Stormwater Management Ordinance and Virginia Stormwater Management Regulations. The County administers the program with oversight of the DEQ. The proper understanding of the meaning of "common plan of development or sale" is critical to understanding the applicability of stormwater management requirements for land disturbing activities. The County's policy concerning common plan of development or sale is contained in Appendix IA. 1.2.3 Floodplain Management Program The County regulates development in the floodplain through its Zoning Ordinance. This Program was developed and is administered to comply with Federal Emergency Management Agency requirements. 1.2.4 Illicit Discharge Detection and Elimination Program Except for specific limited exceptions, only uncontaminated stormwater may be discharged into stormwater systems. The County operates an Illicit Discharge Detection and Elimination Program in accordance with the County of Roanoke Illicit Discharge Ordinance, as required by its MS4 Permit. The DEQ provides oversight of this program. 1.2.5 Municipal Separate Storm Sewer System (MS4) Permit The County of Roanoke is regulated under a General Permit for Small Municipal Separate Storm Sewer Systems issued by the DEQ. MS4 permits generally impact urban areas and they require the locality to implement specific Minimum Control Measures (MCM) to protect local water quality. These MCM's generally fall into six 61 categories: 1. Public Education and Outreach on Stormwater Impacts 2. Public Involvement and Participation 3. Illicit Discharge Detection and Elimination 4. Construction Site Stormwater Runoff Control 5. Post Construction Stormwater Management COUNTY OF ROANOKE 7444X/1/16 1-2 INTRODUCTION 6. Pollution Prevention and Good Housekeeping for Municipal Operations The MS4 Permit also requires that the locality address water impairments that are identified by a Total Maximum Daily Load (TMDL) Study where the locality has been given a Waste Load Allocation (WLA). The County of Roanoke has WLA' for a number of its streams for impairments caused by sediment, bacteria, and PCB'' -s. See the Roanoke County website, Department of Community Development, Stormwater Management page for more information concerning the MS4 Permit and TMDL's. 1.3 Contents of the Manual —The Design Manual is divided into 15 chapters. An overview of each chapter is presented below. Chapter 1 — Introduction. Chapter 1 presents the general background and purpose behind the Design Manual. The chapter documents the goals of the program, the applicable requirements for stormwater management, and the administration of the program. Chapter 2 — Stormwater Management Plan Review and Approval. Chapter 2 presents the process that the applicant and the County of Roanoke follow to assure that the requirements of the stormwater management program and the Stormwater Management Ordinance are met. Chapter 3 — Easements. Chapter 3 establishes the requirements for easements for BMPs and storm drainage systems. Chapter 4 — Stormwater Hydrology. Chapter 4 documents the hydrologic design practices used to establish design flows necessary to design storm drainage systems and BMPs. Chapter 5 — Open Channels. Chapter 5 presents the requirements for open channel hydraulics, including cross section requirements, side slopes, widths, slopes, channel linings, and calculation methods. Chapter 6 — Culverts. Chapter 6 presents the requirements for culverts, including materials, slopes, headwater and tailwater limitations, and design calculation methods. Chapter 7 — Storm Drains. Chapter 7 presents the requirements for storm drains, including storm drain piping sizes, and lengths, and storm drain inlet hydraulics. Chapter 8 —Residential Lot Drainage. 'pP'S��Chapter 8 presents the requirements for residential lot drainage by providing drainage and/or grading the land to direct surface drainage away from building and toward streets, drainage conveyance structures, or sheet flow. COUNTY OF ROANOKE 7444X/1/16 1-3 INTRODUCTION Chapter 9 – Stormwater Detention. Chapter 9 presents requirements and design criteria for stormwater storage facilities. Design criteria include location, sizing, requirements, site access, release rates, and spillway requirements.–T4&-we 4.04 44 r`1...,.re f 11. Chapter 10 – Energy Dissipation. Chapter 10 includes the requirements for velocity and energy reduction devices at the discharge from storm drains, culverts, open channels, and other stormwater management systems. Energy dissipation is required to prevent excessive velocities and erosion in downstream channels. Chapter 11– NOT USED. Chapter 12 – Environmentally Sensitive Areas. Chapter 12 presents requirements for development of environmentally sensitive areas including floodplains, stream buffers, steep slopes, erodible soils, and stormwater pollutant hot spots. Chapter 13 – Geotechnical Studies. (RESERVED) Chapter 14 – Maintenance of Stormwater Management Facilities. Chapter 14 presents the requirements for establishing a maintenance program for stormwater management facilities, and the establishment of a maintenance agreement to assure that stormwater management facilities are properly maintained. Chapter 15 – Inspection and Enforcement. Chapter 15 presents the inspection and enforcement procedures to ensure that construction of stormwater management facilities comply with the approved plans and are properly maintained post-construction.As-built , - Formatted: Highlight requirements are also addressed in this chapter. 1.4 Authority The Design Manual provides supplemental information to implement the provisions of the County Code as they pertain to stormwater management, including storm drainage, and land development. In the event that any part of this Design Manual is held to be illegal or void, this shall not have the effect of making illegal or void the Design Manual in its entirety, or any section thereof, which shall remain effective. 1.5 Applicability —The requirements of this Design Manual apply to all land disturbance activities requiring permits. COUNTY OF ROANOKE 7444X/1/16 1-4 INTRODUCTION —Portions of this Design Manual apply to maintenance and repair of stormwater management facilities and other best management practices after construction is completed. 1.6 Administration 1.6.1 General —The policies and procedures contained within this Design Manual shall be administered by the County of Roanoke, Director of Community Development (Director), or designee. 1.6.2 Manual Amendments This Design Manual may be periodically amended, as recommended by the Director Formatted: indent: Left: 0.75", First line: o", Tab stops: of Community Development, or designee, and approved by the Board of Supervisors. o.7s", Left Amendments to this Design Manual will be posted on the County website, and will — - - Formatted: indent: Left: 0.75", First line: o", Tab stops: become effective on the date listed on the website. It is the manual user's 0.75 , Le ft responsibility to check the website and verify that they have the latest - - Formatted: Font: Bold requirements. 1.6.3 --Exceptions Requests for exceptions of any provisions of this Design Manual shall be made in writing to the County of Roanoke, Director of Community Development. The exception request shall clearly identify the Design Manual provision that is desired to be modified; the justification to support the issuance of an exception, and the alternative measures that are proposed to meet the intent of the Design Manual. All requests for an exception will receive a written response outlining the reasons for approval, or denial, after receipt of all information requested by the Director. In reviewing the request, the Director shall closely examine the proposed development and evaluate the variance request based on the conditions set forth in the Design Manual, County of Roanoke Code, Stormwater Management Ordinance; and the requirements and recommendations of the VA SWM Handbook, VDOT Drainage Manual, VA BMP Clearinghouse, and other sources. 1.6.4 Appeal of Decisions Appeals of decisions may be filed in accordance with the procedures provided in the County of Roanoke Code, Stormwater Management Ordinance. 1.7 Approvals and Permits The applicant is responsible for acquiring all required approvals and permits. 1.7.1 --Local Approvals and Permits COUNTY OF ROANOKE 7444X/1/16 1-5 INTRODUCTION The review and approval of stormwater management plans shall be an integral part of the overall review of site plans. Local permits and approvals include Erosion and Sediment Control Approval, Virginia Stormwater Management Program Permit, Land Disturbance Permit, Zoning Permit, and Building Permit. Retaining walls with a 7.2 --Water and Sewer Approvals and Permits Public water and sewer requires approval from either the Western Virginia Water Authority (WVWA) or the Town of Vinton-(, depending on the geographic location. If the site is located in the Town of Vinton or to the east of the Town of Vinton, within the Town of Vinton service area; then, Town of Vinton approval is required. If public water and/or sewer is located elsewhere in the County; then, WVWA approval is required. For areas not served by public water and sewer, local health department approval is required for wells and onsite sanitary sewage disposal. —1.7.3. --Joint Permit Application Wetlands and streams are protected under several Federal and State programs. Whenever jurisdictional wetlands or streams are impacted by land disturbing activities, a Joint Permit Application must be completed and filed with the Virginia Marine Resources Commission (VMRC). VMRC will distribute the joint permit application to The U.S. Army Corps of Engineers (G01�USACE) and the Virginia Department of Environmental Quality (DEQ). The COLLUSACE and DEQ will consult with other Federal and State agencies in processing the permit application. Upon receipt of an acceptable application the following permits may be issued: • GO&USACE Federal Section 404 Permit • DEQ Water Protection Permit • VMRC Permit party professional experienced in wetland delineation. Plans shall show the surveyed wetland boundary delineation -ate, provide geographic location of the wetland flags, provide acreage of wetlands, and linear footage of streams. Wetlands shall be numbered and flagged in the field. Wetland delineations shall be performed in accordance with the 1987 Corps of Engineers Wetland Delineation Manual and the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Eastern Mountains and Piedmont Region. COUNTY OF ROANOKE 7444x/1/16 1-6 INTRODUCTION Commented [DMH 1]: The height requirement for a building permit for retaining walls changed from 2 feet to 3 feet in the latest Building Code. Formatted: Formatted: Formatted: Formatted: Formatted: Indent: Left: 0.63", First line: 0" 1.8 Reference Sources Managing stormwater runoff from land disturbing activities and prior developed land is a complex issue. There are a number of laws, ordinances and guidance sources that those that design land disturbance activities (land development) must follow. The requirements and recommendations of the following sources, latest editions, are incorporated into this Design Manual by reference. All of the referenced sources are readily available on the internet. 1.8.1_ County of Roanoke Code and Ordinances Design and construction of land disturbing activities shall comply with all relevant portions of the County of Roanoke Code including: • Stormwater Management Ordinance • Erosion and Sediment Control Ordinance • Illicit Discharge Ordinance • Zoning Ordinance • Subdivision Ordinance 1.8.2_ Virginia Law and Regulations Design and construction of land disturbing activities shall comply with all relevant Virginia law and regulations including: • Virginia Stormwater Management Law • Virginia Erosion and Sediment Control Law • Virginia Stormwater Management Regulations • Virginia Erosion and Sediment Control Regulations 1.8.3 --Virginia Manuals, Handbooks, and Websites • Virginia Stormwater Management Handbook, Hereafter throughout this Design Manual referred to as the VA SWM Handbook. • Virginia Department of Transportation Drainage Manual. Hereafter throughout this Design Manual referred to as the VDOT Drainage Manual. COUNTY OF ROANOKE 7444X/1/16 1-7 INTRODUCTION • Virginia Department of Transportation Road and Bridge Standards. Hereafter throughout this Design Manual referred to as the VDOT Standards. • Virginia Department of Transportation Road and Bridge Specifications. Hereafter throughout this Design Manual referred to as the VDOT Specifications. • Virginia Erosion and Sediment Control Handbook. Hereafter throughout this Design Manual referred to as the VA E&SC Handbook. • Virginia Stormwater Management BMP Clearinghouse website (http://vwrrc.vt.edu/swc/). Hereafter throughout this Design Manual referred to as the BMP Clearinghouse. 1.9 --Acronyms and Abbreviations —For clarification, the following is a listing of abbreviations, and acronyms used in stormwater management and throughout this Design Manual. A – Drainage area, acres (stormwater hydrology) A – Cross section area, square feet (open channel or pipe hydraulics) B – VDOT rainfall coefficient, no units (stormwater hydrology) BMP – Best management practice C – Runoff coefficient, no units (stormwater hydrology) Cf– Saturation factor, no units (stormwater hydrology) CMP – Corrugated metal pipe CN – Curve Number (stormwater hydrology) GO&USACE – U.S. Army Corps of Engineers D – VDOT rainfall coefficient, no units (stormwater hydrology) DCR – Virginia Department of Conservation and Recreation De – Critical duration, minutes (stormwater hydrology) DEQ – Virginia Department of Environmental Quality E – VDOT rainfall coefficient, no units (stormwater hydrology) FEMA – Federal Emergency Management Agency g – Gravity coefficient, 32.2 feet/s2 H – Height or depth of water, feet Hf Hi, Hm, FL, Ho – Head losses in piping and structures, feet (storm drain hydraulics) HDPE – High density polyethylene HGL – Hydraulic grade line I – Rainfall intensity, inches per hour (stormwater hydrology) Ip.st – Post -development impervious cover, percentage (water quality Simple Method calculation) I xm.g – Existing impervious cover, percentage (water quality Simple Method calculation) K, Ki, Ko – Head loss coefficients for piping, no units COUNTY OF ROANOKE 7444X/1/16 1-8 INTRODUCTION Lp,e — Pre -development pollutant loading, pounds per year (water quality Simple Method calculation) Lp.st — Post -development pollutant loading, pounds per year (water quality Simple Method calculation) MS4 — Municipal Separate Storm Sewer System n — Manning's equation roughness coefficient, no units (open channel and pipe hydraulics) NFIP — National Flood Insurance Program Q — Stormwater flow, ^a"ars per rainote 'rtpm` at: cubic feet per second (ells) R—Hydraulic radius, feet (open channel hydraulics) r� — Stream bend radius, center, feet (open channel hydraulics) ri — Stream bend radius, inside bank, feet (open channel hydraulics) ro — Stream bend radius, outside bank, feet (open channel hydraulics) S — Slope, feet per feet (open channel or pipe hydraulics) or as a percentage (%) SCS — Soil Conservation Service t� — Time of concentration, hours—minutes (stormwater hydrology) Tp — Time to peak flow,1}ear--minutes (stormwater hydrology) Tr — Time to recede, 4oa�minutes (stormwater hydrology) Tt — Travel time, lminutes (stormwater hydrology) V, Vi, Vo — Velocity, feet per second (open channel and pipe hydraulics) VA E&SC Handbook — Virginia Erosion and Sediment Control Handbook, latest version, as amended VA SWM Handbook — Virginia Stormwater Management Handbook, latest version, as amended VDOT — Virginia Department of Transportation VDOT Drainage Manual — Virginia Department of Transportation, Drainage Manual, latest version, as amended VDOT Specifications — Virginia Department of Transportation, Road and Bridge Specifications, latest version, as amended VDOT Standards — Virginia Department of Transportation, Road and Bridge Standards, latest version, as amended VMRC — Virginia Marine Resources Commission VSMP — Virginia Stormwater Management Program, as administered by PSD DLQ and Roanoke County AZ — Difference in water surface elevation from the inside curve to the outside curve of an open channel, feet (open channel hydraulics) COUNTY OF ROANOKE 7444X/1/16 1-9 INTRODUCTION APPENDIX IA POLICY CONCERNING COMMON PLAN OF DEVELOPMENT OR SALE COUNTY OF ROANOKE '"4x/1/16 IA -1 INTRODUCTION Policy Concerning "Common Plan of Development or Sale" IA.1 General This policy explains how Roanoke County interprets and will apply "common plan of development or sale" in its local VSMP. In the event that this policy conflicts with any guidance issued by DEQ, DEQ guidance will govern. All land -disturbing activities, except those specifically exempted in Section 23-1.3 of the Roanoke County Stormwater Management Ordinance, require approval from Roanoke County as the local VSMP authority and coverage under the state General Permit for Discharges of Stormwater Ffem from Construction Activities prior to commencing land -disturbing activities. Several exemptions apply to land -disturbing activities that disturb less than one acre of land and that are not part of a larger common plan of development or sale. In order to properly apply these exemptions, it is necessary to understand what is meant by "common plan of development or sale." It is critical for developers and land -owners to understand that the permitting exemption can be lost by disturbing more area on a project than planned (exceeding 1 acre land - disturbance) or by taking actions that demonstrate that a small project (less than 1 acre land -disturbance) is part of a larger common plan of development or sale. Actions that increase land disturbance or that create a larger common plan of development after plan approval and during construction will necessitate securing a VSMP permit, may result in possible enforcement and penalty actions, and may result in additional costs and delays due to the need to redesign the site and construct or modify BMPs. Land disturbing activities that are exempt from the requirements of the Stormwater Management Ordinance may not be exempt from the Erosion and Sediment Control stormwater management requirements. Erosion and Sediment Control regulations could still require stormwater management to address Minimum Standard 19. 1A.2 State Definition and Guidance 9VAC25-870-10 defines common plan of development or sale in the following manner: "Common plan of development or sale" means a contiguous area where separate and distinct construction activities may be taking place at different times on different schedules. For the purposes of the VSMP regulations, individual lots within existing residential, commercial, or industrial site plans and subdivision plans that were platted prior to July 1, 2004 may be considered separate land -disturbing activities. COUNTY OF ROANOKE 7444-x/1/16 INTRODUCTION IA -2 1A.3 Discussion and Application 1A.3.1 USEPA guidance(-http://cfpub.epa.gov/npdes/fags.cfm?program id=6 ) A "larger common plan of development or sale" is a contiguous area where multiple separate and distinct construction activities may be taking place at different times on different schedules under one plan. For example, if a developer buys a 20 -acre lot and builds roads, installs pipes, and runs electricity with the intention of constructing homes or other structures sometime in the future, this would be considered a larger common plan of development or sale. If the land is parceled off or sold, and construction occurs on plots that are less than one acre by separate, independent builders, this activity still would be subject to stormwater permitting requirements if the smaller plots were included on the original site plan. The larger common plan of development or sale also applies to other types of land development such as industrial parks or well fields. A permit is required if one (1) or more acres of land will be disturbed, regardless of the size of any of the individually -owned or developed sites. 1A.3.2 The creation of a common plan of development or sale A common plan of development or sale comes into being when there is documentation showing plans or intent to disturb earth regardless of how many phases or how long it will take. Common documents that create a common plan of development include: (a) any announcement or documentation (marketing plans, sign, sales pitch, notice, etc_); (b) any physical demarcation (boundary signs, lot stakes) indicating construction may occur on a specific plot; (c) subdivision plats; or, (d) construction drawings. 1A.3.3 The completion of a common plan of development or sale Once a common plan of development or sale has been created, it remains in force until the contemplated development is substantially completed (less than one (1) acre remaining to be developed). There may be a time when a new developer will want to perform a land disturbing activity on an undeveloped parcel (that was created on or after July 1, 2004), and wants to know if a common plan of development or sale is still valid. In order for the new activity to not be a part of the original common plan of development or sale, it must meet 2 tests. Test 1: Was the original plan, including modifications, ever substantially completed with less than one (1) acre of the original common plan of development or sale remaining (e.g., less than one (1) acre remains to build out)? Test 2: Has there been a clearly identifiable period of time where there is no on- going construction, including meeting criteria for final stabilization? (Roanoke County, by this policy, sets the clearly identifiable period of time at one (1) year.) If the project meets the two tests, then it may be evaluated for permitting purposes on its individual merits. If it does not meet either of the two tests, then it remains part of the original common plan of development or sale, and it requires permit coverage. COUNTY OF ROANOKE 7444--x/1/16 IA -3 INTRODUCTION 1A.3.4 Additional development on an individual parcel after the intended construction is completed When the intended construction on a parcel that is part of a larger common plan of development or sale is completed, any subsequent development or redevelopment of that parcel is considered a new plan of development. 1A.3.5 Effect of adding property to an existing project There are 2 cases where adding land to a project could have permitting impacts. Case 1: A common plan of development or sale has already been created and development of the common plan of development or sale is ongoing. The developer purchases additional property to incorporate into the development. The additional property would become part of the common plan of development or sale. Case 2: A developer subdivides a parcel to create a residential lot. The development of the lot will disturb less than 1 acre. No stormwater permit is required. Prior to a clearly identifiable period of time (1 year) where there is no on-going construction on the first lot, the developer creates a second lot from the original parcel (or markets additional homes prior to creating lots). The development of the second lot would disturb less than 1 acre; however, the development of the first lot and the second lot together would cumulatively disturb 1 acre or more. A larger common plan of development or sale has been created. A permit is required to cover the entire common plan of development or sale (both the construction on Lot 1 as well as Lot 2 and any subsequent lots). Construction on Lot 1 would need to halt until permitting is completed. Stormwater management requirements would need to be met for the entire common plan of development or sale. 1A.3.6 Timing for construction and ownership of BMPs for a common plan of development or sale The technical criteria for stormwater management must be applied to the entire common plan of development or sale. In some cases, portions of a common plan of development or sale may have BMPs with a higher efficiency of pollutant removal or stormwater volume or rate control than other portions of the common plan of development or sale. However, no portion of the common plan of development or sale shall be considered by the County to be completed or be allowed to be occupied until BMPs are completed and functioning that provide stormwater management for that portion of the common plan of development or sale adequate to meet minimum standards (e.g., the construction of BMPs cannot be deferred to a later phase, if the portion of the common plan of development or sale that is currently under construction does not have adequate BMPs to meet the stormwater management technical criteria). COUNTY OF ROANOKE 7444-x/1/16 IA -4 INTRODUCTION BMPs that provide stormwater management for one individual parcel may be on the individual parcel and may be owned and maintained by the property owner of the individual parcel. At the developer's option, BMPs that provide stormwater management for one individual parcel may be made a property association's responsibility as described in the next paragraph. BMPs that provide stormwater management for more than one parcel must be owned and maintained by a property association, consisting of all property owners that are benefiting from the BMP. 1A.3.7 De minimus land disturbance Neither federal nor state definitions or guidance address de minimus land disturbance on a lot within a larger common plan of development or sale. It is obvious that at some point, minor land disturbing activities should not be regulated, within a larger common plan of development or sale; example — disturbance of 20 square feet, on a lot, to erect a temporary sign. For the purpose of implementing the VSMP, Roanoke County considers land disturbance of less than 2,500 square feet to be de minimus and will not fall under the VSMP regulations. If any additional land disturbance occurs on a lot, within a larger common plan of development or sale, within one (1) year of completing the original disturbance, the land disturbance area will be summed. If the summed land disturbance is greater than 2,500 square feet, then the total land disturbed must comply with the VSMP regulations. 1AA Examples 1A.4.1. Example 1 A residential subdivision was started after July 1, 2004. Only 60 of the 100 lots have been developed, with the remaining 40 lots constituting 1 acre or more. No development has occurred since around 2010. A developer intends to develop a vacant'/2 acre lot. This situation applies to a vacant lot in accordance with Section M.3.3. The residential subdivision is a common plan of development or sale. While a clearly identifiable period of time of no construction has passed (Test #2), the project was never substantially completed (Test 91). Therefore, the developer requires a VSMP permit. 1A.4.2 Example 2 A residential subdivision was constructed around 2010. About 80 of the 100 lots have been developed, with the remaining 20 lots constituting 1 acre or more. The owner of one of the constructed homes intends to construct an addition to his home that will disturb 3,000 square feet. This situation applies to an individual parcel after intended construction has been completed in accordance with Section 1.3.4. The residential subdivision is a common plan of development or sale. However, the intended construction has been completed on this lot. Therefore, the addition is treated as a new development project. Since it disturbs less than I acre, no VSMP permit is required. COUNTY OF ROANOKE 7444-x/1/16 1A-5 INTRODUCTION 1A.4.3 Example 3 A regional shopping center was built in the 1990s. It is currently marketing plans to develop several additional buildings in its parking lot. It anticipates that the buildings will be constructed one at a time. The anticipated disturbed area for the construction of each building is less than 1 acre, but the anticipated disturbed area for the construction of all of the additional buildings is over an acre. The common plan of development or sale occurred prior to July 1, 2004, and the original plan is completed. Each of the proposed buildings will disturb under I acre; however, since the 3 buildings are being marketed together, a new common plan of development or sale has been created and the construction of all three buildings must be considered as a single land -disturbing activity. A VSMP permit is required. 1A.4.4 Example 4 A regional shopping center was built in the 1990's. The owner intends to construct a building expansion that will disturb 0.8 acres. Just over a year after completion of the expansion, the owner of the regional shopping center decides to construct another building in its parking lot. The building construction will disturb 0.7 acres. The common plan of development or sale occurred prior to July 1, 2004, and the original plan is completed. The developer intends to construct a building expansion as a stand- alone project. The project will disturb less than I acre; therefore, no VSMP permit is required. After a distinct time period (I year) has passed with no construction activity, the developer decides to construct another building in its parking lot. Since a distinct time period (I year) has passed since the completion of the building addition, and since the new building is not part of the building expansion plan, and since less than I acre is disturbed, no common plan of development or sale is created and no VSMP permit is required. Note If the building expansion and additional building in the parking lot were part of an overall renovation plan that was intended to be constructed in phases, then a common plan of development or sale would have been created and a VSMP permit would have been required. 1A.4.5 Example 5 A congregation intends to build a new church in phases. Phase 1 is for a multipurpose sanctuary and parking and the construction will disturb 2 acres. Phase 2 is for a classroom expansion and its construction will disturb 0.5 acres. The phased church construction is a common plan of development or sale. A VSMP permit will be required for Phase I and Phase 2. COUNTY OF ROANOKE 7444--x/1/16 IA -6 INTRODUCTION 1A.4.6 Example 6 A congregation intends to build a new wing for education use and expand the parking lot. No construction has been built for over a year. The construction will disturb 0.8 acres. The proposed project is separate from the original church construction; therefore, it is not part of a larger common plan of development or sale. Since disturbed area is less than I acre, no VSMP permit is required. 1A.4.7 Example 7 A developer has a plan approved that indicates that 0.9 acres will be disturbed. During construction, the developer actually disturbs 1.2 acres. The developer's plan indicates that less than I acre will be disturbed. Therefore, no VSMP permit was required. However, the developer actually disturbed over 1 acre. Therefore, the County issues a "Stop Work" order until a VSMP permit can be issued. A stormwater management plan meeting the stormwater management regulation technical requirements must be prepared and submitted, along with an executed and recorded maintenance agreement, revised performance security, and additional fees. The developer must ensure that an adequate SWPPP is prepared and available at the site. No further land -disturbance activities may occur until these items are completed and a VSMP permit is issued. The County may undertake other enforcement actions and penalties, depending on the circumstances. 1A.4.8 Example 8 An existing fast food restaurant is part of a partially developed commercial area. It plans a renovation that includes some parking lot changes and a small expansion to its seating area. The construction disturbed area is 0.7 acres. The commercial area is part of an active common plan of development or sale; however, the intended construction (fastfood restaurant) on this parcel has been completed. In accordance with Section M.3.4, the renovation is a separate land -disturbing activity. Since less than I acre is disturbed, no VSMP permit is required. 1A.4.9 Example 9 A developer intends to construct a subdivision in two phases. He intends to develop Phase 1 first, followed by Phase 2. Since the subdivision is a common plan of development or sale, the two phases are treated as a single land disturbance activity and the determination of whether or not adequate stormwater management is being provided is analyzed for the subdivision as a whole. Stormwater management for the subdivision will be accomplished by a combination of BMPs on individual lots, to serve the individual lots; and BMPs intended to serve multiple lots. Due to the characteristics of COUNTY OF ROANOKE 7444-x/1/16 IA -7 INTRODUCTION the site and the layout of the design, the overall plan indicates that the proposed BMPs for Phase 1 are not adequate to meet the pollutant removal requirements, but that with the construction of Phase 2, the overall effectiveness of the BMPs will be increased so they are adequate to meet the pollutant removal requirements for both Phase 1 and Phase 2 upon completion of Phase 2. The proposed plan is unacceptable in accordance with Section 1.3.6. Even though it is expected that portions of the common plan of development or sale will have more effective BMPs than other portions of the common plan of development or sale, and even though the common plan of development or sale is evaluated as a single land -disturbance activity; It is not acceptable to construct a portion of the common plan of development or sale without concurrent construction of adequate BMPs such that the technical requirements of the stormwater management regulations are met as each portion of the common plan of development or sale is completed. 1A.4.10 Example 10 A land -owner owns a parcel with existing public road frontage. The current zoning and subdivision requirements would allow for the parcel to be subdivided into 8 lots without the need for any additional public infrastructure. The property owner divides the parcel to create one 1/4 acre lot and constructs a single family house on it. Several years after completion of the single family house, the property owner divides the parcel again to create another 1/4 acre lot and constructs another single family house. Each project is separated by adequate time that they are independent projects and no VSMP permit is required. 1A.4.11 Example 11 A land -owner owns a 10 acre parcel with existing public road frontage. The current zoning and subdivision requirements would allow for the parcel to be subdivided into 8 lots without the need for any additional public infrastructure. The property owner divides the parcel to create one 1/4 acre lot and sells the individual lot to a developer to construct a single family house on it. After the property sale, the landowner posts a sign on his property stating that "land is available for development and that the owner will subdivide". The owner has created a larger common plan of development or sale by marketing development on his parcel. The developer may continue with his project to construct a single family house, since the property was sold to him prior to the creation of the larger common plan of development or sale. However, any further construction on the land- owner's parcel will require a VSMP permit. COUNTY OF ROANOKE 7444--x/1/16 IA -8 INTRODUCTION STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL CHAPTER 2 Chapter 2 — Stormwater Management Plan Review and Approval In order to maintain the character and integrity of neighborhoods, to promote excellence of development, to prevent undue traffic and environmental hazards, and to encourage the most harmonious development and use of land, a site development plan, including a storm water management plan and sediment control plan, is required for commercial and residential development and shall be submitted to the County of Roanoke's Department of Community Development. Plans should be submitted in compliance with the Digital Plan Submission Guide policy. (http://www.roanokecountyva.gov/index.aspx?NID=317) These plans will be distributed to the appropriate departments and divisions for review and approval. When required, the applicant is also responsible for submittals to the Virginia Department of Transportation, Virginia Department of Environmental Quality, Western Virginia Water Authority, Town of Vinton, and other applicable regulatory agencies for their review and approval. When applicable, all of these entities must approve the site development plan prior to the issuance of any permits for all types of developments as required by the Zoning Ordinance, Subdivision Ordinance, Erosion and Sediment Control Ordinance, and Stormwater Management Ordinance. In cases where jurisdictional waters exist on the proposed site, the applicant may need to obtain approvals and/or permits from any or all of the following agencies: the U.S. Army Corps of EngineersU( SACE), the Federal Emergency Management Agency, the Virginia Department of Environmental Quality (DEQ), and the Virginia Marine Resource Commission (VMRC). Itis the responsibility of the applicant to obtain all necessary permits from USACE, DEO, VRMC, etc and provide Roanoke County with a copy of the required permit(s). Approval of plans by Roanoke County does not alleviate the applicant's liability of obtaining the required permit(s). 2.1 Overview of the Review and Approval Process No application for land development, land use conversion, or land disturbance can be approved, and no permits issued, without all of the elements required for a VSMP permit, as more fully described in the County Stormwater Management Ordinance and 9VAC25-870- 55. These elements generally include a permit application, erosion and sediment control plan, stormwater management plan, stormwater maintenance agreement, performance bond, fees, and executed development agreements. An agreement in lieu of a stormwater management plan may be accepted for a detached single family residence that is not part of a common plan of development. —The submittal, review, and approval of site development plans, including stormwater management plans will follow the Roanoke County Land Development Procedures. This document is available from the County of Roanoke Department of Community Development website (http://www.roanokeco=va.gov/index.aspx?NID-317). COUNTY OF ROANOKE STORMWATER MANAGEMENT PLAN 7/A444x/1/16 REVIEW AND APPROVAL 2-1 Formatted: Highlight STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL CHAPTER 2 2.2 Concept Stormwater Management Plan Submittal A concept site development plan, including a concept stormwater management plan, is is strongly encouraged by the County of Roanoke when the proposed - - Formatted: Font: sold development meets any of the conditions set forth in the Roanoke County Land Development Procedures. A concept site plan or concept stormwater management plan may also be submitted for any project at the applicant's option. If submitted, the concept site development plan, including a concept stormwater management plan, should addressed items as outlined in Roanoke County's Land Development Procedures. 2.3 Stormwater Management Master Plan Submittal A stormwater management master plan and calculations are required for all phased proiects that are part of a common plan of development. The master plan shall address grading, stormwater conveyance, and stormwater management BMPs for the overall development. The master plan is required to be approved prior to issuance of any permits. Each phase must provide adequate stormwater treatment to address the stormwater requirements for each individual phase. The Stormwater Master Plan shall show how the Desiener will address stormwater management requirements for the entire proiect. At a minimum, the plans shall show the overall development, the location and type of the proposed BMPs required to treat the entire development, and contours. Additionally, the Designer shall provide applicable drainage areas to the BMPs and provide an accompanying VRRM worksheet to support the overall design" The final stormwater management master plan shall be appropriately sealed and signed by a licensed professional in adherence to all minimum standards and requirements pertaining to the practice of that profession as required in the VA Stormwater Management Regulations. 2.34 Stormwater Management Plan Submittal —An approved site development plan and a local VSMP permit, is executed agreement in lieu of a stormwater management plan, is required prior to issuance of any other permits. The final stormwater management plan shall be appropriately sealed and signed by a licensed professional in adherence to all minimum standards and requirements pertaining to the practice of that profession as required in the VA Stormwater Management Regulations. The VSMP permit application information will be reviewed by the County of Roanoke. In addition to Roanoke County's review, the Virginia Department of Transportation may also COUNTY OF ROANOKE 7/A444x/1/16 2-2 STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL Formatted: Highlight STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL CHAPTER 2 review the site development plan with the stormwater management plan, as appropriate. Plans for review by these entities must be submitted directly to them, when required. All commercial protects or sites within a common plan of development that disturb between 0.90 and 0.99 acres shall provide point(s) with northing and castings to delineate the disturbance limits on the plans. The plans shall include a note that the disturbance limits are required to be delineated by a surveyor in the field and orange safety fence shall be installed to mark the delineation. All plans required for single family protects that are part of a common plan of development or commercial proiects shall be prepared using the State Plane Coordinates and NAVD 88. Single family protects that are not part of a common plan of development and do not require as-builts nor a flood study are not required to be tied to the State Plane Coordinate System. 2.45 Submittal of Stormwater Calculations —Calculations shall be submitted to the County of Roanoke supporting the stormwater management and storm drainage design. Calculations shall be well organized and coordinated with the design to allow for efficient review by the County. Calculations shall be bound together in a booklet or stapled together, depending on the number of pages. Each page of She calculations should include the date .prepared, a, unique page number_, and the date , - Formatted: Highlight revised. Formatted: Highlight � Formatted: Highlight Calculations shall follow the following general format: Formatted: Highlight • Cover Sheet — The cover sheet shall contain the project name, property tax parcel(s) number(s), applicant's name, design professional's name, calculation date, and (for final calculations) the seal and signature of the design professional. • Table of Contents — A table of contents shall be provided where the calculations exceeds 25 pages, or where appropriate to assist the reviewer in locating information in the calculations. • Introduction — A general description of the project providing information to assist the reviewer in understanding the nature and scope of the project and of the storm drainage and stormwater management facilities that are proposed. This should also explain existing and proposed conditions. • Criteria and Methodology — A listing of the basic design criteria for water quality compliance, channel protection, flood protection, and TMDL (where appropriate). • References — A listing of references that are used in the calculations COUNTY OF ROANOKE STORMWATER MANAGEMENT PLAN 7/A444x/1/16 REVIEW AND APPROVAL 2-3 STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL CHAPTER 2 • Assumptions —A listing of all assumptions, and justification of the assumptions that are used in the calculations. • Analysis - The body of the calculations clearly labeled as to what stormwater BMPs or storm drainage system the calculations are for. The calculations shall be step-by- step to ensure that a reviewer that is not familiar with the project can follow the progression of the calculations. If computer printouts are provided highlight the input and output information and ensure that the input information is clearly supported in the calculationsand that the output is properly evaluated in the summary and conclusions. All calculation parameters must be fully supported and documented and include the design storm frequency, intensity and duration, times of concentration mans (including segment lengths, elevations, slopes, and flow types), soil curve numbers or runoff coefficients; calculations identifying pre -and post -development peak runoff rates and total runoff volumes for each watershed area, infiltration rates (where applicable), culvert, storm drain, and open channel capacities, flow velocities, data on the increase in rate and volume of runoff for the specified design storms, pre - and post -development phosphorous runoff rates and all other calculations needed to support the proposed design. • VRRM Worksheet — A digital copy of the VRRM worksheet shall be submitted with the plan submittal. Roanoke County uses an annual rainfall of 42" for all proiects located within Roanoke County and precipitation rates from the NOAA precipitation chart for the Roanoke County Airport. • Drainage Area Maps —Drainage area maps shall be provided for storm drainage inlets and BMPs. Pre and post drainage area maps shall be provided. • Summary and Conclusions — A summary of the results, preferably in tabular or chart form for each storm drain system and stormwater BMP to indicate that the land disturbing project meets County requirements and any conclusions. Provide Oi, 02, and Oio for pre and post conditions. Appendices and Attachments — Any supporting information such as pre -developed and post -developed drainage area maps, soils maps, U.S.G.S. quadrangle maps, NOAA precipitation chart, design nomographs, and computer printouts. Drainage maps must be clearly delineated and labeled to indicate the amount of area draining to each BMP and storm drainage inlet. Formatted: Underline Calculations that are not well organized and coordinated with the design shall be - I Formatted: Font: sold, Underline reiected and the submittal shall not be reviewed until proper calculations are submitted. COUNTY OF ROANOKE 7/A4 -/44x/1/16 2-4 STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL STORMWATER MANAGEMENT PLAN REVIEW AND APPROVAL CHAPTER 2 2.56 Changes and Modifications to an Approved Plan Changes to an approved subdivision or site plan, including an approved stormwater management plan, must be formally submitted for review to the County of Roanoke Department of Community Development at the counter with the Permit Technicians or via toe Roanoke County's FTP site. The County of Roanoke, upon receipt of the resubmittal of an approved development plan, shall review and approve or disapprove the resubmitted plan according to the Roanoke County Land Development Procedures. Approval or disapproval of the resubmitted plan shall be made in writing to the applicant. Any use, arrangement, location, or construction not in compliance with the approved plan is a violation of the County Code. COUNTY OF ROANOKE STORMWATER MANAGEMENT PLAN 7/A444x/1/16 REVIEW AND APPROVAL 2-5 EASEMENTS CHAPTER 3 Chapter 3 - Easements 3.1 General This manual addresses three types of easements: • Private drainage easements; • Public drainage easements; and • Access Easements Easements may be required as a part of a subdivision plat or site plan review. The purpose of this section is to provide policy, procedures, and guidelines for establishing easements for storm drainage and BMPs. Easements may grant certain rights and privileges to the County or other public entity such as VDOT for public easements, or to specific landowners and/or the County in the case of private easements. Proposed easements will be shown conceptually on preliminary site plans. The easements will be in final form on the submitted stormwater management plan and will be consistent with the design on final plats and site plans. Easements shall be dimensioned to allow them to be located in the field by providing dimensional ties to property corners, or centerline bearings and distances. Where easements are aligned with property lines, offset dimensions will be provided. Verification of easement locations will be required as a part of the as -built drawing requirements. If drainage or BMPs are found to have been constructed outside of the easement; then, the permittee will be responsible for vacating the original easement and recording a new easement, in the proper location, at the permittee's expense. Easements should not split property lines. Where an open channel or storm drain system runs parallel to a property line, it should be offset from the property line an adequate amount so that the easement is totally contained on the property that contains the open channel or storm drain and not be split onto the adjacent property. This provision allows construction of fences at the property line. All easements, shall connect to public access points. Easements shall be wide enough, and shall be located to allow convenient access for inspection and repairs, regardless of the minimum widths given herein. 3.2 Drainage Easements Public drainage easements giving the County or a public entity such as VDOT the right to discharge stormwater runoff onto private property is required for all public storm drainage systems and BMPs that are located on private property. This includes open channels, culverts, inlets, storm drains, stormwater management basins, and other best management practices that are owned, operated, and maintained by the County or other public entity such as VDOT. COUNTY OF ROANOKE EASEMENTS ^//14 x/1/16 3-1 EASEMENTS CHAPTER 3 Public storm drainage systems are used to convey stormwater drainage from public property, public right-of-way, or another public storm drainage system through private property. Once the stormwater is discharged into a perennial or intermittent stream, or is otherwise managed, a public drainage easement is not required. Public BMPs are used to provide appropriate stormwater management for stormwater runoff generated by land development on public property. Examples of situations where a public drainage easement is required include: • Concentrated stormwater runoff from a County or County School Board owned site discharging to private property, including any open channels leaving the property or any storm drains leaving the property. • Concentrated stormwater runoff from public streets and open channels or storm drains from the public street right-of-way which passes onto any private property. Private drainage easements giving a private party the right to discharge concentrated stormwater runoff onto downstream private property is required whenever connection is made to a downstream private storm drainage system. No buildings, foundations, structures, fences or walls, not associated with the storm drainage system or BMP shall be located within a drainage easement. In addition, easements that contain open channels shall not be obstructed by fences or unmanaged vegetation. The closest edge of a storm drainage easement shall not be located within 10 feet of the rear wall of any individual single-family residential structure, except where the easement is required to access a BMP that is solely serving the single-family residence. Underground utility lines and structures shall be kept at least 5 -feet horizontal from drainage pipes, structures, and channels, except at utility crossings. Utility crossings at drainage easements shall be at as near 90-degress as possible. Where a storm drainage system terminates or starts short of a property line, adequate drainage easements shall be dedicated to allow for maintenance and future extension of the system through the property. 3.2.1 Culverts and Storm Drains The minimum width of drainage easements for culverts and storm drains shall be as follows: Pipe Size (width) Minimum Easement Width # Smaller than 36" 20 feet 36" — 42" 25 feet 48" — 60" 30 feet COUNTY OF ROANOKE EASEMENTS ^//14 x/1/16 3-2 EASEMENTS CHAPTER 3 66" — 78" 35 feet `Minimum width given above is for installations with depths of cover of 10 -feet orI Formatted: Font: Bold less (measured at the top of pipe). For each additional 5 -feet of cover over 10 -feet (rounded up), the minimum easement width shall be increased by 10 -feet. for pipes that are larger than given in the table above, and for installations that , - Formatted: Font: Bold result in minimum easement widths greater than 50 -feet due to installation depths, the minimum easement width shall be set by the County based on the width requirements to access the pipe in the future for repair. Drainage easements at the inlet and outlet of all culverts and storm drain inlets shall include the areas inundated by the headwater during the 100 -year storm. The easement shall extend a minimum of 10 feet from culvert inlets and outlets and storm drain inlets to allow for maintenance access. Where steep slopes and/or deep fills exist, additional easement area may be required to allow for proper access. Storm drain easements shall cross private driveways at perpendicular angles to the extent practical. 3.2.2 Open Channels The minimum width of the drainage easement required is dependent on the top width of the channel as indicated in Figure 3-1. The County may require wider easement width, if the open channel is located in rough terrain and additional width is required for access for inspection or repair. COUNTY OF ROANOIKE ^//14 x/1/16 Figure 3-1 Minimum Easement Width for Open Channels 3-3 EASEMENTS EASEMENTS it CHAPTER 3 EASEMENT WIDTH ]0" - —10' TOP WIDTH OF CHANNEL DEPTH OF PROPOSED CHANNEL PROPOSED CHANNEL WIDTH OF BO TT OM 3.3 Access Easements Access easements giving the County the right to access private property for the purpose of inspecting, and if necessary to maintain or repair private BMPs is required for all private BMPs. This includes stormwater management basins, filter strips, bioretention trenches, underground detention areas, and all other BMP's. All structures, pond areas, embankments, inlet and outlet channels, and access and working areas necessary to inspect, maintain, and repair the facilities shall be included in access easements. The 100 -year flooding area of all stormwater basins or other holding structures shall be contained within the access easement area. In addition, all BMPs shall contain a minimum 20 -foot working area around all stormwater management basins and a minimum 10 -foot working area around all other BMPs and an access easement connecting to a public road. Depending on the size and location of the stormwater management facility, more than one vehicle accessible access easement connecting to a public road may be required. All stormwater structures and BMPs shall be accessible by vehicle. Areas within an access easement that are intended to be vehicle accessible shall have a maximum slope of 10 percent for unpaved surfaces and 18 percent for paved surfaces. The vehicle access shall be a minimum of 12 feet in width. The minimum width for an access easement shall be 20 feet. All access easements shall connect to a public road or right of way; unless a suitable blanket access easement is provided. 3.4 Maintenance of Easements COUNTY OF ROANOKE EASEMENTS 74/14-x/1/16 3-4 EASEMENTS CHAPTER 3 Ownership of land within easements shall remain with the property owner. The property owner shall have the responsibility of maintaining the easement areas free of any obstructions or use that would interfere with the rights or privileges granted by the property owner. The property owner shall not alter the existing ground elevations or in any way redirect or obstruct stormwater flow. Any alterations to easements resulting in obstruction or redirection of flow will be returned to existing elevations immediately at the cost of the property owner. COUNTY OF ROANOKE ^//14 x/1/16 3-5 EASEMENTS EASEMENTS APPENDIX 3A STANDARD EASEMENT AGREEMENTS County of Roanoke — Permanent Drainage Easement Agreement COUNTY OF ROANOKE ^//14 x/1/16 3A-1 APPENDIX 3A EASEMENTS EASEMENTS APPENDIX 3A Exemption Claimed: Grantee is exempted from recordation taxes and fees pursuant to § 58.1- 811A(3), Code of Virginia. Prepared By: Tax Map No.: Property Owners: THIS DEED OF EASEMENT, made this and between AND day of 20 , by whether one or more, "Grantor") and the BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA ("Grantee"). WITNESSETH: That for and in consideration of the sum of One Dollar ($1.00), paid in hand at and with the execution and delivery of this Deed of Easement, and other good and valuable consideration, the receipt, adequacy and sufficiency of which is hereby acknowledged, the Grantor does hereby GRANT and CONVEY with General Warranty and Modern English Covenants of Title unto the Grantee, its successors and assigns, the following described easement, to -wit: A perpetual RIGHT and EASEMENT, approximately feet in width, to construct, operate, maintain, inspect and repair or replace a drainage system and related improvements including slope(s), if applicable, together with the right of ingress and egress thereto from a public road, upon, over, under, and across a tract or parcel of land belonging to the Grantor, acquired by deed dated and recorded in the Clerk's Office of the Circuit Court of Roanoke County, Virginia, in Deed Book , page , and designated on the Roanoke County Land Records as Tax Map No. (the "Property"). The location of said easement is more particularly described on the plat attached hereto as "Exhibit A" and by this reference made a part hereof (the "Plat"), and shown traversing as shown on Exhibit A. The Grantee agrees to restore and repair any actual damage to Grantor's Property which may be directly caused by the construction, reconstruction, or maintenance of said project except as hereinafter provided. The Grantor agrees that the Grantee will not be expected to restore the Property to the identical original condition, but rather as near thereto as is practicable, and that the Grantor will cooperate with the Grantee in effectuating such restoration. It is expressly agreed between the parties hereto that the Grantee and its agents shall have the right to inspect the easement herein granted and to cut, clear, and remove all undergrowth, obstructions, or improvements lying within or upon-a�jaee to said easement, that in any way endanger or interfere with the proper use of the same. The Grantor covenants that no building or structure shall be erected upon or within the easement herein granted or placed in such location as to render the said easement inaccessible. In the event that this covenant is COUNTY OF ROANOKE EASEMENTS ^//14 x/1/16 3A-2 EASEMENTS APPENDIX 3A violated, the Grantee shall not be obligated to repair, replace, or otherwise be responsible for such improvements if damaged or removed. The Grantor acknowledges that the plans for the aforesaid project as they affect the Property have been fully explained to the Grantor or Grantor's authorized representative. The fixtures, facilities, lines, utilities, and any other improvements placed upon, under, or across the Property by the Grantee shall remain the property of the Grantee. The easement herein granted is in addition to, and not in lieu of, any easement or right-of-way now in existence or which may be acquired in the future. The Grantor covenants and aggress for themselves, and for their heirs, successors, successors in title, executors, legal representatives, and assigns that the consideration aforementioned and the covenants herein shall be in lieu of any and all claims to compensation and damages by reason of the location, construction, operation, maintenance, or reconstruction of or within the easement herein granted. The grant and provision of this Deed of Easement shall constitute a covenant running with the land for the benefit of the Grantee, its successors and assigns forever to have and hold unto the Grantee, its successors and assigns forever. , County Administrator, or his designee, of Roanoke County, Virginia, hereby joins in the execution of this instrument to signify the acceptance by said Board of Supervisors of the real estate conveyed herein pursuant to Ordinance No. adopted by the Board of Supervisors of Roanoke County, Virginia, on the day of IN WITNESS WHEREOF, the parties hereto have caused this agreement to be executed on their behalf. GRANTOR: (SEAL) (SEAL) (Name) (Name) GRANTOR ACKNOWLEDGMENT COUNTY OF ROANOKE EASEMENTS ^//14 x/1/16 3A-3 EASEMENTS APPENDIX 3A State of - Count -,,/City of: to wit: The foregoing instrument was acknowledged before me this day of and (Notary Public Signature) (Notary Public Printed Name) My Commission expires: Registration # BOARD OF SUPERVISORS OF ROANOKE COUNTY. VIRGINIA: (SEAL) (County Administrator of Roanoke County, Virginia) COUNTY ACKNOWLEDGMENT State of- County/City of: , to wit: The foregoing instrument was acknowledged before me this day of by , County Administrator, on behalf of the Board of Supervisors of Roanoke County, Virginia. (Notary Public Signature) (Notary Public Printed Name) My Commission expires: Registration # COUNTY OF ROANOKE 74/14—x/1/16 3A-4 (SEAL) EASEMENTS STORMWATER HYDROLOGY Chapter 4 - Stormwater Hydrology CHAPTER 4 Stormwater hydrology defines the means and methods to calculating stormwater runoff from a designated area. This section documents the hydrologic practices used to establish design flows necessary to prepare the required stormwater peak flow and storage calculations. 4.1 References Except where more stringent requirements are presented in this Design Manual, stormwater hydrology shall comply with state requirements. The primary design references are: • VDOT Drainage Manual • VA SWM Handbook • BMP Clearinghouse 4.2 Design Frequencies 4.2.1 General Design frequencies shall be selected consistent with good engineering practice and economics. The design frequency requirements given in this Design Manual are minimum, specific conditions may dictate that less frequent design frequency should be used. 4.2.2 Storm Drainage Systems Storm drainage systems consist of manmade open channels, culverts, and storm drains. Designs shall be based on the following minimum design storm frequencies: Manmade Open Channels: , - Formatted: Underline Minor Channel Capacity 10 -year Minor Channel Protective Lining (Drainage Area 5 acres or less) 2 -year Minor Channel Protective Lining (Drainage Area over 5 acres) 10 -year Major Channel Capacity 100 -year Major Channel Protective Lining 10 -year (100 -year if potential for catastrophic failure) Culverts: - - Formatted: Underline Principal Arterial Roads 25 -year COUNTY OF ROANOKE 7444X/1/16 4-1 STORMWATER HYDROLOGY STORMWATER HYDROLOGY Other Roads CHAPTER 4 10 -year Storm Drains 10 -year - - I Formatted: Underline All storm drainage designs for open channels, culverts, and storm drains shall be checked for the 100 -year flow condition where there is the possibility of flooding residences, commercial or industrial buildings, overtopping primary roads, experiencing significant economic loss, or catastrophic failure. Where justified by the consequences of failure, the minimum design frequency shall be increased. 4.2.3 Stormwater Management Facilities Designs shall be in accordance with the VA SWM Handbook and BMP Clearinghouse. 4.3 Time of Concentration (t�) and Travel Time (Tt) 4.3.1 General Time of Concentration (Q is the length of time required for a drop of water to travel from the most hydraulically distant point in the watershed, or subwatershed to the point of analysis. Travel Time (T) is the length of time required for that same drop of water to travel from the study point at the bottom of the sub - watershed to the study point at the bottom of the whole watershed. The travel time is descriptive of the sub -watershed by providing its location relative to the study point of the entire watershed. Therefore Time of Concentration is the summation of Travel Time values for the various consecutive flow segments. Travel Time and Time of Concentration generally consist of four flow types - overland flow, shallow concentrated flow, channelized flow, and pipe systems. Calculations shall be reviewed for reasonableness and the results shall be revised if needed to provide a reasonable velocity and flow time that will best represent the study area. When designing a drainage system, the flow path is not necessarily the same before and after land disturbing activities have been completed. Therefore, the travel time path shall be reflective of the actual conditions both before and after the land disturbing activities. In some cases, runoff from a portion of the drainage area that is highly impervious may result in a greater peak discharge than would occur if the entire area were considered. In this case, adjustments can be made to the drainage area by disregarding those areas where flow time is too slow to add to the peak discharge. COUNTY OF ROANOKE 7444X/1/16 4-2 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 To prevent small drainage areas from skewing the time of concentration calculation results, when establishing sub drainage areas for analysis, the largest sub drainage area shall be no greater than 5 times the area of the smallest sub drainage area. Time of concentration maps shall include segment lengths, elevations at beginning and end of segment, slopes, and flow types. 4.3.2 Overland Flow Overland flow is flow that occurs at the upper end of a watershed, where flow is not concentrated and there are no channels. The length of overland flow shall be reflective of actual conditions and shall normally be po greater than 150 feet-------- Formatted: Underline Where the overland flow does not contain any slopes exceeding 5% AND if the soils are not designated as highly erodible, a maximum length of overland flow of 200 feet may be used. Highly erodible soils are designated as United States Department of Agriculture Natural Resources Conservation Service land capability classification (LCC) classes IIIe, IVe, VI, VII, or VIII or having an erodibility index greater than or equal to 8.—Overland flow shall be calculated using the Seelye chart contained in the Appendix 4A for the Rational Method or TR -55 for the SCS Method. Roughness coefficients (Manning's n) for sheet flow can be found in the TR -55 Manual. 4.3.3 Shallow Concentrated Flow Shallow concentrated flow is the flow that occurs when minor rivulets form just downstream from the overland flow. The maximum allowable length for shallow concentrated flow shall be 1000 feet. Shallow concentrated flow shall be calculated using the Overland Flow Velocity - - Formatted: indent: Left: r', First line: 0" Chart from HEC -19 or by using the nomograph entitled "Time of Concentration of Small Drainage Basins," developed by P.Z. Kirpich. Copies of the Kirpich chart and nomograph are contained in Appendix 4A and shall be used for the Rational Method. TR -55 shall be used for the SCS Method. Results from the Kirpich nomograph shall be multiplied by 0.2 for paved channels. 4.3.4 Channelized Flow Channelized flow occurs where stormwater flow converges in gullies, ditches, and natural or man-made water conveyances, including storm drain pipes and culverts. Channelized flow shall be calculated by use of the nomograph entitled "Time of Concentration of Small Drainage Basins," developed by P.Z. Kirpich. A copy of the nomograph is contained in Appendix 4A and shall be used for the Rational COUNTY OF ROANOKE 7444X/1/16 4-3 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 Method. TR -55 shall be used for the SCS Method. Results from Kirpich nomographs shall be multiplied by 0.2 for paved channels. 4.3.5 Pipe Flow Pipe flow is the flow that occurs through culverts and storm drains. Use full -flow pipe velocities, unless it may be demonstrated that the pipe will operate at partial full conditions. If it can be shown that the pipe will operate at partial full conditions, then the partial full pipe velocity may be used. Design of flow through culverts is presented in Chapter 6. Design of flow in storm drain systems is presented in Chapter 7. 4.4 Selection of Methodologies 4.4.1 General There are a variety of widely used hydrologic methodologies. Each has its strengths and weaknesses. In the interest of standardizing hydrologic calculations, the following methodologies will be used for all projects, unless the County agrees that good engineering practice dictates the use of another method. 4.4.2 Peak Discharge Methods for Design of Storm Drainage Systems The fAiena4-Rational +netl}ed-Method may be used to design storm drainage conveyance systems for drainage areas up to 200 acres. Minimum time of concentration when using the Rational Method is 5 minutes. The SCS method may be used for drainage areas up to 10 square miles. For drainage areas greater than 10 square miles, calculations shall be performed using at least two separate methods as described in the VDOT Drainage Manual (SCS method, regression equations, and/or stream gage data). The design peak flow shall be selected based on a professional evaluation of the results of the various methods. 4.4.3 Hydrograph Methods for Design of Stormwater Management Facilities COUNTY OF ROANOKE 7444X/1/16 4-4 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 The SCS method may be used iii all eases. The SCS ffle�had fffd4 be used whefe miffi4es of shall be used in the design of stormwater BMPs and ponds. Minimum time of concentration when using the SCS method is 6 minutes. 4.5 Methodologies Following is an abbreviated discussion of each method. Refer to the VDOT Drainage Manual and the VA SWM Handbook for a more complete discussion. 4.5.1 Rational Method �1. General ------------------------------------------- Formatted: Font: Bold The Rational Method is expressed as: Q=CMA Where: Q = Peak flow rate of runoff, cubic feet per second (cfs) f= Saturation factor -------------------------------- Commented[AG1]: C = Runoff coefficient representing a ratio of runoff to rainfall (dimensionless) I = Average rainfall intensity for a duration equal to the time of concentration for a selected return period, inches per hour (in/hr) A = Drainage area contributing to the design location, acres (ac) B. Saturation Factor ........ Formatted: Font: Bold The saturation factor (Cf) is an adjustment factor for modifying the runoff coefficient (C) for storms that are less frequent than a 10 -year recurrence interval. The product of Cf and C should not be greater than 1.0. - - Formatted: Indent: Left: 1.44", First line: 0.25" Recurrence Interval (Years) Cf 2, 5, and 10 1.0 25 1.1 50 1.2 100 1.25 Where the product of Cf and C is greater than 1. 0, use 1.0. C. )2unoff Coefficient Formatted: Font: Bold COUNTY OF ROANOKE 7444X/1/16 4-5 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 The runoff coefficient (C) is a variable of the Rational Method that requires significant judgment and understanding for proper selection. A range of C - values for a given land use is given in Appendix 4A. The coefficient must account for all the factors affecting the relation of peak flow to average rainfall intensity other than area adjustment. Some of these factors include land slope, condition of cover, and antecedent moisture condition. As the slope of the drainage basin increases, the selected C -value should also increase. The lower range of C -values should be used where the majority of the slopes are less than 2 -percent. The average range of C -values should be used where the majority of slopes are 2 to 5 -percent. The higher range of C - values should be used where the majority of the slopes are greater than 5 - percent. The higher range of C -values should be used in clayey and other less pervious soil areas. D. Average Rainfall Intensity See the VA SWM Handbook. An IDF curve file is located on the Roanoke County webpage for use with HydroCAD and Hydraflow at �ttp://www.roanokecopptyva_gov/index.aspx?NID=317- Q factors are not , - Field Code Changed included for 025 and Qioo in the IDF files and should be accounted for the , - Formatted: Not Highlight calculations. JE._ Drainage Area Formatted: Font: Bold Drainage area (DA) is measured in acres and is determined from evaluating a topographic map of the area. 4.5.2 Modified Rational Method COUNTY OF ROANOKE 7444X/1/16 4-6 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 �1. General ------------------------------------------- Formatted: Font: Bold The Modified Rational Method is a means to generate hydrographs for small drainage areas. The parameters for the calculation are the same as the Rational Method, except that a series of average rainfall intensities from different storms with the same frequency and different durations are computed. The hydrograph from the critical duration storm is used to design stormwater management facilities. The Modified Rational Method recognizes that the duration of a storm is often longer than the time of concentration. This longer duration storm, even though it produces a lower peak Q, can produce a larger volume of runoff than the storm duration equal to the actual time of concentration of the drainage area. In order to ensure the proper design of stormwater management facilities, the runoff for the critical storm duration shall be used. —B. Hydrograph Assumptions Formatted: Font: Bold The hydrograph generated by the Modified Rational Method is based on the following assumptions: • Time of Concentration (Q = Time to Peak (Tp) = Time to Recede (Tr) • The length of the critical duration storm (De) is from 0 minutes until the time of selected duration. • The rate of runoff is 0 at time 0 minutes. The rate of runoff increases linearly with time until the peak rate of runoff is reached at time Tp. • The peak rate of runoff is maintained from time Tp until the duration of the storm (De). The rate of runoff then decreases to 0 at time De plus Tr. • The peak rate of runoff is based on the average rainfall intensity (I) for the given storm duration. C._ Critical Duration Storm Formatted: Font: Bold The critical duration storm is the storm of a given frequency that has a duration that yields the greatest volume of storage in a stormwater management facility when the storm hydrograph is routed through the stormwater management facility. The critical duration storm may be estimated for preliminary purposes; however, the actual critical duration COUNTY OF ROANOKE 7/4/14x/1/16 4-7 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 storm must be determined by routing the various duration storm hydrographs through the stormwater management facility and demonstrating which storm duration gives the greatest volume of storage. 4.5.3 SCS Method A. General ------------------------------------------- Formatted: Font: Bold The SCS Method may be used for computing peak flows and hydrographs for storms of selected return frequencies. This approach considers the time distribution of the rainfall, the initial rainfall losses to interception and depression storage and an infiltration rate that decreases during the course of a storm. The information required to use the SCS Method to determine the peak rate of runoff, or to develop a runoff hydrograph is: • 24-hour total rainfall, and rainfall distribution type. The 24 hour precipitation rate is based upon NOAA values at the Roanoke Airport. These values can be found on Roanoke County's website or NOAA's website. • Time of Concentration (Q in minutes, rounded up to the nearest whole minute; • Curve Number (CN), which is determined by Cover Types and Hydrologic Soils Groups; and • Drainage Area (A) in acres. If the drainage basin is over 20 acres, or if it contains areas of different land - - Formatted: indent: Left: 1.25", First line: o" uses, the drainage basin should be divided into sub -basins. Each sub -basin should have similar land uses. When sub -basins are used, the following information is required to use the SCS Method to determine the peak rate of runoff, or to develop a runoff hydrograph: • 24-hour total rainfall, and rainfall distribution type. The 24 hour precipitation rate is based upon NOAA values at the Roanoke Airport. • Time of Concentration (Q in minutes for each sub -basin, rounded up to the nearest whole minute; • Curve Number (CN), which is determined by Cover Types and Hydrologic Soils Groups, for each sub -basin; • Drainage Area (A) in acres, for each sub -basin; and COUNTY OF ROANOKE 7444X/1/16 4-8 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 Travel Time (Tt) of the flow from each sub -basin as it flows through downstream sub -basins. If the SCS Method is being used to design a stormwater management facility, the following additional information is required to rout the runoff hydrograph through the facility and to generate an outflow hydrograph: • Elevation — Storage Relationship • Elevation — Discharge Relationship B. �4-hour Rainfall and Distribution - " " I Formatted: Font: Bold The 24-hour rainfall is determined by fir..f f«,.,,..,...,.., 1,.,.. ted 4 A....,.44,7:., AB T-4 4:ni44411 d is4*ib..r:,.., rYpe f ,. Oh-@ n,.,.HR-ke 378 -1 -lay is -r.,.., Ti NOAA precipitation amounts for Roanoke Airport. C. Curve Number------------------------------------ --" Formatted: Font: Bold The SCS method uses a combination of soil conditions and land use (ground cover) to assign a runoff factor to an area. These runoff factors, or runoff curve numbers (CN), indicate the runoff potential of an area. The CN requires significant judgment and understanding for proper selection. A table containing CNs for various cover types and soils conditions is contained in Appendix 444A. When calculating existing rates of runoff (pre -construction), assume that all cover types are in good hydrologic condition. Hydrologic Soils Groups (HSG) include types A, B, C, and D, with type A being the most permeable and type D the least permeable. Appendix 4B includes a listing of most soil names with their respective hydrologic soils types. Urban/udorthents soils shall be considered a Type D soil for design purposes. Soils maps for the Roanoke Valley may be obtained by referring to USDA web soil survey. Colored soil maps with support HSG documentation shall be included in the calculations packet D. Prainage Area - Formatted: Font: Bold COUNTY OF ROANOKE 7444X/1/16 4-9 STORMWATER HYDROLOGY STORMWATER HYDROLOGY CHAPTER 4 Drainage areas for each sub -basin should be identified on an appropriate topographic map. E. _Elevation — Storage Relationship _ Formatted: Font: Bold When runoff hydrographs are being routed through a stormwater management facility, the relationship between the elevation (or depth) of stored water in the facility and storage volume needs to be known and input into the calculation. Often this information is obtained by determining the pond area bounded by contour lines on a grading plan. Enough data pairs (elevation — storage) must be provided to properly model conditions at transition points. F. _Elevation — Discharge Relationship ...... ------------ Formatted: Font: Bold When runoff hydrographs are being routed through a stormwater management facility, the relationship between the elevation (or depth) of stored water in the facility and the discharge flow rate from the facility needs to be known and input into the calculation. The development of this relationship requires an understanding of the design conditions and underlying hydraulic principles. The hydraulic principals and equations governing the discharge rate will often change several times at varying elevations. These include weir flow, orifice flow, culvert inlet control, culvert outlet control, open channel flow, and possible effects from downstream backwater. 4.7 Drainage Area Analysis To prevent the undersizing of stormwater management components, upstream properties conditions shall be considered in the drainage area analysis. Stream channel and improvements to any conveyance system shall be analyzed. When a project site contains or is divided by multiple drainage areas, stormwater - - Formatted: indent: Left: r', First line: o" management of each drainage area must be addressed separately. Over detention of one flow is not an effective solution to achieving water quantity goals. Improving the channel immediately downstream is not effective in controlling the actual flow release from the site beingdeveloped, nor does it reduce the impact of the flow on properties further downstream. COUNTY OF ROANOKE 7444X/1/16 4-10 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4A DESIGN AIDS FROM CHAPTER 6, VDOT DRAINAGE MANUAL Overland Flow Nomagraph — Seelye Overland Flow Velocity Time of Concentration for Small Drainage Basins — Kirpich Average Velocities for Estimating Travel Time for Shallow Concentrated Flow Rational Method Runoff Coefficients Runoff Curve Numbers for Urban Areas Runoff Curve Numbers for Cultivated Agricultural Areas Runoff Curve Numbers for Other Agricultural Areas COUNTY OF ROANOKE 7444X/1/16 4A-1 APPENDIX 4A STORMWATER HYDROLOGY STORMWATER HYDROLOGY nVFBT . A Nil Fl .nW - 4ZFF7 .VF APPENDIX 4A RURWTED WJTN P€:RWISSION FROM 'DATA BOOB FOR CIVIL ENGINEERS` VOL. I-aESIGN Esm EOLTION (19511 BY €.E.SEELYE COUNTY OF ROANOKE 7444s/1/16 STORMWATER HYDROLOGY 4A-2 900 35- 800 T� = 0:2251-0.42 S-o.i�) C-I.o 700 600 T, -Overland Flow Time, minutes 30 L=Length of Strip, feet 500 Paves S=Slope, foot/foot C=Rational "C" Value 400 0.8 1 25- 304 O.i 0.6 dare $oil 0.5 20 a 200 Poor 0.4 Grass Surface-- s�4 LU L Gross p+Vera -Q.3 a 0.5 Uj Z l 00 Sur#aae `- -- 1.0 IL 15- 90 A c) �7- a ` I1► a so Dense - . z FL Grass 0.2 60 LL 5 O z 20 ,s a 40 o 30 LL- iQ Q Uj LE4 ¢ z z a ct e� 7, z c� 10 6 - OVERLAND FLOW TIME RURWTED WJTN P€:RWISSION FROM 'DATA BOOB FOR CIVIL ENGINEERS` VOL. I-aESIGN Esm EOLTION (19511 BY €.E.SEELYE COUNTY OF ROANOKE 7444s/1/16 STORMWATER HYDROLOGY 4A-2 STORMWATER HYDROLOGY APPENDIX 4A OVERLAND FLOW VELOCITY .1 2 3 5 1 Y 3 S Io z4 50 so C,f w 3 Id tLb IL O if7 S Ld co W � g 1 74444xnn6 2 .3 .3 1 2 s 5 VELOCITY, Y ( FT I SEC) 4A-3 Si] 30 20 -j5 90 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4A TIME OF CONCENTRATION - KIRPICH (Note: MultiDly Tc by 0.2 for Paved Channels) Tc = 13.03948 B-039 X1.13 '% - P AV11M£, MIMES 30 - lim6im rEef L - 1.FkVrR.FEE TIME nF EONCENTRATIDN OF SMALL DRAINAGE BASINS COUNTY OF ROANOKE 7/1444/1/16 4A-4 STORMWATER HYDROLOGY Soo EXAMPLE Tc (MW 4a@ HEffinr - 14113 FT. 2014 - LENUTF!3 MMIA €T. rimE up cmCcNTRATT[]11 = i+ KjM- 158 200 100 150 Fa PA -lag 613 x a o 40 58 50901 3a 4.0 Z: 3o 3� @! 25 e w 1 zaP�Pl9; 1000 l0 � Sip 5 5 4 4 s 3E�J 290 15� 2 � x Ilvrd aei ' by P X Yurine st iFnF €nrd csr.ni*WV&_ h0 Nu. 6. Jux 1940. P. 363' TIME nF EONCENTRATIDN OF SMALL DRAINAGE BASINS COUNTY OF ROANOKE 7/1444/1/16 4A-4 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4A AVERAGE VELOCITIES FOR ESTIMATING TRAVEL TIME FOR SHALLOW CONCENTRATED FLOW .lo WE, ..01 - 005 ra„r��r.�� —Y�wawY_waaw ww�wr�wwwwawr swasw:_arrw�n ���ii�taa rrwwi�7�w rrmrr�r1rrrre r�wlwl�wa�m�w"'� l � w,wlwl ME OnoMam9201KEaaIfrwnII=-=E 1��i�1{■■I■■�■�■ti mmmmu ■=u='■n■i����llllll�urrei #•>Ir�■1■■ 1•��i■ EffN1 ■■WINUMB111111111TAN►.lBBEM■og ■■�1� iwwrar iw ww�wr�aaa��w rwra�ar ilr� wa�ra�wwwm i»iar flit aaFia�a•�tiiilr■ ■■■ =�■■1■a11■■r;m1;■■■■■■■�i■ios.■ ��ii��■■Hli Irwwrrrwsww waw;!# 003111Rio13111==11,11■EMI 1■f�iillllii■■!!�i!#11•trl•■ 111 1j1H11jJjJB"FjjrIlll■=N0N n��l�■111 arrrror.rrrirrr wrraa��rrira. 1m1=viawrirr �ww�wl7w w# Zwrirfairasrrr:ww.ira�+=lam _r_w orw ww1# .a.aop .... �1llllllMilAl awl■0 1 BONERNiNal4ial[a#ww#w�� some R t tlll/il�1lt■1I1f■]■�■ rwwaa�arrera��r rrrr` awry �wwwarw�w� ai rrariPlfur�r wrrn as �f__ mow_ lorrsra�rarrs•r_w some mono loss ii ��w1■?�wri�w rril Si V �#a•i�ra�# �araalrZwi=on l�ii11>t■1■■J111'i<tii� �1111�#�►. ■n ww■ aar .rarrr� r•wR .rr�aa_aww_ M sf! 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The lowest range of runoff coefficients may be used for flat areas (areas where the majority of the grades and slopes are 2% and less). 2. The average range of runoff coefficients should be used for intermediate areas (areas where the majority of the grades and slopes are from 2% to 5%). 3. The highest range of runoff coefficients shall be used for steep areas (areas where the majority of the grades are greater than 5%), for cluster areas, and for development in clay soil areas. 4. The residential runoff coefficients include impervious and pervious amounts in the coefficient. * Lower runoff coefficients should be used for permanent or established conditions (post - construction), i.e. sizing stormwater management basins. * Higher runoff coefficients should be used to design roadside ditch linings (construction). The design considers the ditch lining as not yet established. - - - Formatted Table Formatted: Font: 11 pt ** Based upon Manufacturer's recommendation and BMP Clearinghouse specifications. - I Formatted: Font: 12 pt COUNTY OF ROANOKE 7444X/1/16 4A-6 STORMWATER HYDROLOGY STORMWATER HYDROLOGY RUNOFF CURVE NUMBERS FOR URBAN AREAS APPENDIX 4A COUNTY OF ROANOKE 7444X/1/16 4A-7 STORMWATER HYDROLOGY Soil Group A B C D Cover type and hydrologic condition Open space (lawns, parks, golf courses, cemeteries): Poor condition (grass cover < 50%) 68 79 86 89 Fair condition (grass cover 50% to 75%) 49 69 79 84 Good condition (grass cover > 75%) 39 61 74 80 Impervious areas: Paved parking lots, roofs, driveways (excluding right-of-way) 98 98 98 98 Streets and roads: Paved; curbs and storm drains (excluding right-of-way) 98 98 98 98 Paved; open ditches (including right-of-way) 83 89 92 93 Gravel (including right-of-way) 76 85 89 91 Dirt (including right-of-way) 72 82 87 89 Urban districts: Commercial and business (85% average impervious area) 89 92 94 95 Industrial (72% average impervious area) 81 88 91 93 Residential districts by average lot size: 0.10 or less, town houses (65% average impervious area) 77 85 90 92 '/4 acre (38% average impervious area) 61 75 83 87 1/3 acre (30% average impervious area) 57 72 81 86 'h acre (25% average impervious area) 54 70 80 85 1 acre (20% average impervious area) 51 68 79 84 2 acre (12% average impervious area) 46 65 77 82 Developing urban areas: Newly graded areas(pervious areas only, no vegetation) 77 86 91 94 COUNTY OF ROANOKE 7444X/1/16 4A-7 STORMWATER HYDROLOGY STORMWATER HYDROLOGY RUNOFF CURVE NUMBERS FOR CULTIVATED AGRICULTURAL AREAS APPENDIX 4A Cover Treatment Hydrologic Soil Group A B C D type condition Fallow Bare soil --- 77 86 91 94 Crop residue Poor 76 85 90 93 Cover (CR) Good 74 83 88 90 Row Crops Straight Row (SR) Poor 72 81 88 91 Good 67 78 85 89 SR and CR Poor 71 80 87 90 Good 64 75 82 85 Contoured (C) Poor 70 79 84 88 Good 65 75 82 86 C and CR Poor 69 78 83 87 Good 64 74 81 85 Contoured & Terraced Poor 66 74 80 82 (C & T) Good 62 71 78 81 C&T and CR Poor 65 73 79 81 Good 61 70 77 80 Small Grain SR Poor 65 76 84 88 Good 63 75 83 87 SR and CR Poor 64 75 83 86 Good 60 72 80 84 C Poor 63 74 82 85 Good 61 73 81 84 C and CR Poor 62 73 81 84 Good 60 72 80 83 C&T Poor 61 72 79 82 Good 59 70 78 81 C&T and CR Poor 60 71 78 81 Good 58 69 77 80 Close -seeded SR Poor 66 77 85 89 or broadcast Good 58 72 81 85 Legumes or C Poor 64 75 83 85 rotation Good 55 69 78 83 Meadow C&T Poor 63 73 80 83 Good 1 51 67 76 80 Comments: Crop residue cover (CR) applies only if residue is on at least 5% of the surface throughout the year. Poor = Factors impair infiltration and tend to increase runoff Good = Factors encourage average and better than average infiltration and tend to decrease runoff. COUNTY OFROANOKE 74/14x/1/16 4A-8 STORMWATER HYDROLOGY STORMWATER HYDROLOGY RUNOFF CURVE NUMBERS FOR OTHER AGRICULTURAL AREAS C'.nmmPntc- APPENDIX 4A Cover Hydrologic Soil Group A B C D type condition Pasture', grassland, or range- Poor 68 79 86 89 continuous forage for grazing Fair 49 69 79 84 Good 39 61 74 80 Meadow — continuous grass, 30 58 71 78 protected from grazing and generally mowed for hay BrusW — brush -weed -grass mixture Poor 48 67 77 83 with brush as the major element Fair 35 56 70 77 Good 30 48 65 73 Woods — grass combination Poor 57 73 82 86 (orchard or tree farm) Fair 43 65 76 82 Good 32 58 72 79 Woods Poor 45 66 77 83 Fair 36 60 73 79 Good 30 55 70 77 Farmsteads — buildings, lanes, 59 74 92 86 driveways, and surrounding lots PasturePoor < 50% ground cover or heavily grazed with no mulch Fair 50% to 75% ground cover and not heavily grazed Good > 75% ground cover and lightly or only occasionally grazed Brush Poor < 50% ground cover Fair 50% to 75% ground cover Good > 75% ground cover Woods Poor — Forest litter, small trees and brush are destroyed by heavy grazing or regular burning Fair — Woods grazed but not burned, and some forest litter covers the soil Good — Woods protected from grazing, litter and brush adequately cover soil COUNTY OF ROANOKE 7444X/1/16 4A-9 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B APPENDIX 4B DESIGN AIDS FROM CHAPTER 4, VA SWM HANDBOOK Rational Equation Coefficients for SCS Hydrological Soil Groups, Urban Land Uses Rational Equation Coefficients for SCS Hydrological Soil Groups, Rural and Agricultural Uses Roughness Coefficient "n" for Manning Equation — Sheet Flow Roughness Coefficient "n" for Manning Equation — Pipe Flow Roughness Coefficient "n" for Manning Equation — Constructed Channels Roughness Coefficient "n" for Manning Equation—Natural Stream Channels Hydrologic Soils Names in Virginia (7 sheets) COUNTY OF ROANOKE ^//1�t4X/1/15 4B-1 STORMWATER HYDROLOGY + O OO O N N O O, l— V) 0 0 0 0 0 O o 0 0 �o,ry�o�m mmmry cgo0o00 0000 0000,c�m 000�ov c�a,ry�o�m mryryry A o 0 0 0 0 0 0 0 0 0 +Ovo,cgoo �o�tN� 0 o�ry�o�m mmmm 10 O O o 0 Cl 0 0 0 0 o O moo,-�o�m mc�c�c� c500000 0000 o O�t 00 N0 l- v1 N 0 co m NNNN U 6 0 0 0 0 0 0 0 0 0 + O a, cq V) m O oo �o oo,ry�o�m mmryry 10 O O o 0 0 0 0 Cl 0 0 0 �c 00 0 a, �o m o - o r- m cq cq cq cq Q c500000 0000 0 00�N 'r\ioo- NN° — p W o 0 0 0 0 0 0 0 0 0 0 C7 +o noocq a,rovc c`!c`!c`!c`!q o 'o o 0 0 0 0 0 0 0 0 u o moo,-��N NNN� o c500000 0000 0 �^o oOoor- cqo, o� coo O or�ry ry x 0 0 0 0 0 0 0 0 0 0 w � u N O o a w IO o CIO w � z a W cd m Cd occ �� �00000 a P. °ciwaaaaa I W i + 00 0 o o M M ry ry o �o �o r- �o �o 0 o n 0 0 0 0 0 0 0 0 0 O o 0 0 0 0 c5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A O O O O O O O O O O O O O O O +� ooN�NooM- N- O 0 0, W 't 'o O O O O O O O O O O O O O O o a 00 W)0,00 00000 0000r - N N r� W� -t W� -zt Wi V -zt c5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o l� V N O N--� N N N— — -- W) V v, vi V U o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 + 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 vl N �oN -��o�� : m AM m M M M M MM 0000000 000 000 0 N� -� o�ov�M AMM MMry p 0 W o 6 6 0 0 0 0 0 0 0 0 0 0 0 0 C7 + M vi o 0 0 0� M M ry ry ry ry ry ry 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 goo 000vMryry ryryry o c5o 0000000 000 000 s°. N o 0 0 0� ry ry ry ry o W •o � kna� ^a N x °u o C7 0 C7 0 C7 0 C7 0 C7 0 C7 0 C7 0 C7 0 C7 0 C7 0 C7 0 C7 � 1 0 0 N 0 0 N 0 0� .c' co 0 0� .c' o o� o W FSA. Z U v v o 0 0 uE y v o U 0 0 UE y v o U 0 0 UE w a a foo y � 0 0 _ C o U O STORMWATER HYDROLOGY ROUGHNESS COEFFICIENT "n" FOR MANNING EQUATION - SHEET FLOW COUNTY OF ROANOKE 7444X/1/16 Surface Description n Smooth Surfaces (Concrete, 0.011 Asphalt, Gravel, or Bare Soil) Fallow (no residue) 0.05 Cultivated Soils: Residue Cover < 20% 0.06 Residue Cover > 20% 0.17 Grass: Short Grass Prairie 0.15 Dense Grasses 0.24 Bermuda Grass 0.41 Range (Natural) 0.13 Woods: Light Underbrush 0.40 Dense Underbrush 0.80 4B-4 APPENDIX 4B STORMWATER HYDROLOGY STORMWATER HYDROLOGY ROUGHNESS COEFFICIENT "n" FOR MANNING EQUATION - PIPE FLOW Material "n" Range From To Coated Cast Iron 0.010 0.014 Uncoated Cast Iron 0.011 0.015 Vitrified Sewer Pipe 0.010 0.017 Concrete Pipe 0.949013 0 01:7 Common Clay Drainage Tile 0.011 0.017 Corrugated Metal (2 2/3 x Yz) 0.023 0.026 Corrugated Metal (3x1 and 6x1) 0.026 0.029 Corrugated Metal (6x2 structural plate) 0.030 0.033 HDPE 0.012 COUNTY OF ROANOKE 7444X/1/16 4B-5 APPENDIX 4B STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B ROUGHNESS COEFFICIENT "n" FOR MANNING EQUATION - CONSTRUCTED CHANNEL Lining Material "n" Range From To Concrete Lined 0.012 0.016 Cement Rubble 0.017 0.025 Earth, Straight and Uniform 0.017 0.022 Rock Cuts, Smooth and Uniform 0.025 0.033 Rock Cuts, Jagged and Irregular 0.035 0.045 Winding, Sluggish Canals 0.022 0.027 Dredged Earth Channels 0.025 0.030 Canals with Rough Stony Beds, 0.025 0.035 Weeds on Earth Banks Earth Bottom, Rubble Sides 0.028 0.033 Small Grass Channels: Long Grass — 13" 0.042 Short Grass — 3" 0.034 COUNTY OF ROANOKE 7444X/1/16 4B-6 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B ROUGHNESS COEFFICIENT "n" FOR MANNING EQUATION - NATURAL STREAM CHANNEL Channel Lining "n" Range From To 1. Clean, Straight Bank, Full Stage 0.025 0.030 No Rifts or Deep Pools 2. Same as #1, Some Weeds and Stones 0.030 0.035 3. Winding, Some Pools and Shoals, 0.033 0.040 Clean 4. Same as #3, Lower Stages, More 0.040 0.050 Ineffective Slope and Sections 5. Same as #3, Some Weeds and Stones 0.035 0.045 6. Same as #4, Stony Sections 0.045 0.055 7. Sluggish River Reaches, Rather 0.050 0.070 Weedy with Very Deep Pools 8. Very Reedy Reaches 0.075 0.125 COUNTY OF ROANOKE 7/4/14x/1/16 4B-7 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B Sail Narnf Hydgru Safi MOM P H,, d9 A Soil .Nam Hyp. APPOMATTOX B AQUENCS D AQUULTS 17 ARAPAIOE 11II7 ARCOLk C ARGENT D ASBURN= C ASHE B ASHLAR B ASSATEAGUE A ATKINS D ATLEE C AUGUSTA C AURA J3 AUSTINVII-.LE B AXIS D AYCOCK B BACKBAY D BADIN B BAIZE D BAILEGAP B BAMA B BAYBORO D REACHES D BECKHAM B BELHAVEN D BELTSVU-LE C BELVOIR C BEM C BERMUDIAN B BERM B BIBB D BILTMORE A BIRDSBORO B BLADEN D BLAMT'ON C BLAND C BLEAKHILL C BLUEMONI* B BOHICKET 1] B+OIAC B BOLLING C BOLTON B BONNEAU A BOOKWOOD B ROTETOURT C BOURNE C BOWMANSVU.LE Bm BRADDOCK B BRADLEY C BRANDYWINE C BRECKINOCK B BREMO C BRENTSVILLE C BROADWAY B BROCKROAIi C BRUSHY B BUCHANAN C BUCKHALL B BUCKS B BUCKTON B BUBFSTAT B BUGLEY CID BUNCOMBE A BURK.ETOWN C BURROWSVILLE C CALVERTON C CALVIN c CAMOCCA AID CANEYVLLI.E C CARBO C CARDIFF B CAROLINE C CARRVALE D CARTECAY C CATASKA D CATHARPIN C CATLETT 0D CATOCTIN C CATPOINT A CAVERNS B CECIL B CHAGRIN B CHAPANOKE C COUNTY OF ROANOKE 74/14x/1/16 STORMWATER HYDROLOGY 4B-8 STORMWATER HYDROLOGY APPENDIX 4B Sail ame CHASTAIN Hxdori D 5m Name CHATUGE Hyd"p D Soil Name CHAVIES Hrdgrn S CI-IFNNEBY C CHESTER B CHEWACLA C CHICI{AHOMINY D CHLLHOWTE C CHINCOTEAGUE D CHIPLEY, C C&IISWELL D CHRISTIAN c CID C CLAPHAM* C CLEARBROOK D CLIFTON C CLUBCAF D CLYAffiR D COASTAL BEACH D CODORUS C COLFAX C COLLEEN C COLVARD B COMBS B COMUS B CONETOE A CONGAREE B COOSAW B COROLLA D CORYDON D COTACO C COURSEY C COWEE B COXIVILLE D CRAIGSVILLE p GRAVEN c CREEDMOOR C CROT€}N D CULLEN C CULPEPER C DALEVTTI.F D DANDRIDGE D DAVIDSON B DAW WOO B; D DECATUR B VARIANT DEK-ALB C DELANCO c DELOSS B/D DERROC B DILLA RD c DOGUE c DOROVAN D DOTHAN B DRAGSTDN C DRALL B DRY?OND D DUCKSTON AID DUFFIELD B DUL.LES D DUMFRIES. S DUNBAR D DUNNING D DUPLIN C DURHAM B DYKE B EBBING C EDGEHILL C EDNEDYTOWN B EDNEYVIL.LE B EDOM c ELBERT D ELIOAK C ELIOK C EL.KTON CID ELLIBER A EL.SINBORA B EMPORIA C ENDCAV C COUNTY OF ROANOKE 7444X/1/16 4B-9 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B Sall Nam Elyd-tp Sail N9une Hyd4,rp 5611 Name H ydap ENON C ENOTF C ERNEST C FU13ANKS B EULONLA C EUNOLA C EVANSHAM D EVARD B EVERGREEN B EXUM G FACEVILLE B FAIRF'AX B FALLSINGTON BJD FAUGUIER C FAYWOOD C FEATHERSTONE D FISHERMAN D FLATWOODS C FLETCHER B FLUVANNA C FLtJVAQUENTS D FORESTDALE D FORK C FRANKSTOWN B FREDERICK B FRENCH C FRIPP A GAILA B GAINESBOR0 C GALESTOWN A GEORGEVILLE B GILPIN C GLADEHFLL B GLENELG B GLE1+Iyrn.?z C GLENWOOD B GOLDSBORO B GOLDSTON C GOLDVEIN C GORESVILLE' B GREENLEE B GRI3viSLEY R GRITNEY C GROSECLOSE C GROVER B GUERNSEY C GULLION C GUNSTOCK C GUYAN C GWINNETT B HAGERSTOWN C VARIENT HALEWOOD B KARTLETON B HATBORO D HAWKSBILL B RAYESVILL.E. B HAYMARKET D HAYTER B HAYWOOD B HAZEL C HAZEL C HAZELTON B HELENA C CHANNERY HER.NDON B HFWASSEE B HOADLY C HOBUCKEN D HOGELAND* C HOLLYWOOD D HUNTINGTON B RYATTSVILLE B HYDE BVD HYDRAQUENTS B INGLEDC?VE B =FL L C/D COUNTY OF ROANOKE 7444X/1/16 4B-10 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B ,,%il NoXq IRONGATE ¢ B Soil Namc IUKAA Irgtm C Soil N2iLE IZAGORA Hudvrn C JACKLAND D JEDBURG C JEFFERSON B JOHNS C JOHNSTON D JUNALUSKA B KALN A B KELLY D KEMPSVILLE B I{ENANSVILLE A KENAAISVILLE c KEYPORT C V ARLANT KIIdKORA D KINSTON BJD KLEJ B KLU,IESVI LLE CJD KONNAROCK c LAIDIG C LAK_ERUR.ST A LAKELAND A LANE A D VARIANT LANSDALE B LAROQUE B LAVNES D LEAF D LEAKSVH,LE D LECK KILL B LEEDSVILLE• B LEETONIA C LEGORE LEHEW c LENOIR D LEON B D LEVY ❑ LEW B LEV4'ISBERRY 8 LIBRARY D LIGNUiki C LILY 13 LINDSIDE c LITTLETOE B LITZ c LLOYD C LOBDELL B LODI B LOUISA B LOL11SBURG B LOWELL C LLYCKE'TTS B LUCY A LUGNUM C LUMBEE BID LUNT C LYNCHBURG C MACOVE B MADISON B MAGOTAIA D MANASSAS B MANOR B MANTACHIE c MANT'EO CID MARBIE c MARQ0 B MARLBORO B MARK B MARUMSCO c MASADA C MASSANETTA B MASSANUTTEN B MATAFEAKE B MATNELFLAT B MATTAN D COUNTY OF ROANOKE 7444X/1/16 4B-11 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B Soil Name Hydgrp Soil Name Aydorij Suil .NaM H4`df.rn MATTAPEX C MATTAPONI C MAURERTOWN D MAYODAN B MCGARY C MCQUEEN C MEADOWS D MEADOWVILI.E B ME.CKLENBURG C MEGGETT D MELI+A D MELVIN D M L"(xm A MINNIEEV ILLS C ML= D ALLUVIUM MOLENA A MONACAN C MONGLE C MONONGAHELA C MONTALTO C MONTItE;SSOR* B MONTROSS C MOOMAW C MORRISONVILLE' B MOR VEN B MOUNT LUCAS C MT WEATHER'S B MUCKALEE D MUNDEN B MURRML B MYATT D MYATT VARIANT D MYERSVILLE B NAHUNTA C NANSEMOND C NASON B NAWN$Y D NEABSCO C NESTORIA CJD NEVARC C NEWARK C NEWBERN C NEWFLAT D NEWHAN A NEWMARC C NICHOLOSON C NTMMO D NIRA C NOLICHUCKY R NOLIN B NOMERVILLE B NORFOLK B OAKHILL B OAKLET C OATLANDS B OCCOQUAN B OCI-MOCKONEE B OKEETEE D OPEQLION C ORANGE D ORANGEBUItG B ORENDA S ORISKANY B OSIER Ao OTHELLO C..'D PACOLET B PACTOLUS A PAGEBROOK D PAMLICO D PAMUNKEY B PAMUNKEY A PANORAMA B VARLkNT PARKER B PARTLOW D PASQUOTANK Rn PEAKS C PEAWICK D PENN GD COUNTY OF ROANOKE 7444X/1/16 4B-12 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4B Soil tiumc Ilyd rp $oil Nam Hydgrp SW Na= Ficd= PHILO B PHMOMOMT' B PINEYWOODS D PINKSTON B PISGAH C POCATY D POCOMOK.E BID P61NDE=R B POLAWANA ArT) POOLER VARIANT D POPE B POPLWENTO C PORTERS B PORTSMOUTH Bo POUNCEY D PUNCO D PURCELLVnIF B PUIRDY D RABUM B RAINS BID RAMSEY D RAPIDAN B RAPPHANNOCK D RARITAN C RAYNE B READINGTON C REAVILLE. C RFVMW, A RIGLEY B TUON B RIVERVMW 13 ROANOKE D ROHRERSVILLE D ROSS B ROWLAND C RUMF'ORD B RUSHTOWN A RUSTON B SAFELL B SASSAFRAS B SASSAFRAS B VAtTNCX)K B SAVANNAH C SCATTBRSVTLLE• C SCHAFFE'NAKER A SBABROOK C SEDGEFIELD C SEKH, B SENECA B SEQUOIA C SI3ELOCTA B SHENVAL B SHERA DO B SIMVA C SHOT O YEIi B SINDION B SKETERVH,I:E C SLABTOWN B SLAGLE C SLICKENS B SNICKERSVILLE B SPEEDWELL B SPESSARD A SPIVEY B SPOSTSYLVANLA C SPRIGGS G SPRINGWOOD B STANTON D STARR C STATE B STEIN&BURG C STONEVILLE B STUART C STUWTOWN B SUCHES B SUDLEY B SUTEQUEHANNA D SUFFOLK B SUISDLEY B SUSQUEHANNA D SWAMP D COUNTY OF ROANOKE 7444x/1/16 STORMWATER HYDROLOGY 4B-13 STORMWATER HYDROLOGY APPENDIX 4B Cnil Name SWEETAPPLE ILYA= B 5611 Name SWIh•SLEY C Rail Name SYCOiINE Hydgrp D SYLCO C SYLVATUS D TALLADEGA C TALL.APOOSA C TARBORO A TATE B TATUM B TETOTUM C THUNDER B THURMONT B TIDAL MARSH D TBOERVLLLE B TIOGA B TOCCOA B TODDSTAV D TOMOTLEY av TOMS C TOR TA C TOTIER C TOYAWAY BiD TRAPPIST C TREGO B TREN19OLM D TUCKAHOE B TUMBLING B TURBEVILLE C TUSQUITEE B TYGART C UCHEE A U7DIFLUVE.NTS B UNISON B VANCE C VARINA C VAUCLUSE C VER.TREES B WADESBORO B WAHE� D WAKUL.LA A WALLEN B WARMINSTER C WATAUGzA $ WATEREE. B WATT D WAXPOOL D WEAVER C WEAVEP-TON* C WEBBTOWN C WEDOWEE B WEEKSVILLE BA) WEHADKEE D WEIICERT CSD WESTMORELAND B WESTON D WESTPHALLA B WEVERTON B WHEELING B WHITE STONE D WIIITEFORD B WICKHAM B WILKES C WOLFGAP B WOODINGTONT BID WORSHAM D WRIGHTSBORO C WRYICK B WURNO C V,TMCK B YADKIN CID YEMASSEE C YEOPIM B YORK C ZEPP B ZION C ZOAR C COUNTY OF ROANOKE 74/14x/1/16 STORMWATER HYDROLOGY 4B-14 STORMWATER HYDROLOGY APPENDIX 4C APPENDIX 4C INFORMATION FROM VDOT HYDRAULIC DESIGN ADVISORIES Rainfall Intensities (inches/hour) for the Roanoke Valley (Based on VDOT HDA 05-03) COUNTY OF ROANOKE 7444X/1/16 4C-1 STORMWATER HYDROLOGY STORMWATER HYDROLOGY APPENDIX 4C Note: For use with the Rational Method only. Use NOAA precipitation chart for SCS Method. RAINFALL INTENSITY (INMR) FOR THE ROANOKE VALLEY Table based on VDOT Hydraulic Design Advisory HAD 05-03 If = B / (% + D)E where: If = Rainfall intensity for a given recurrence interval, f, in inches per hour t� = Watershed time of concentration (assumed to equal the storm duration), in minutes B,D,E = As taken from HDA 05-03 table for [Roanoke] [Roanoke (city)] based on the designated storm frequency. COUNTY OF ROANOKE 7444k/1/16 4C-2 STORMWATER HYDROLOGY Storm Duration (min) 5 10 15 20 25 30 35 40 45 60 75 90 105 120 2 4.39 3.51 2.94 2.54 2.24 2.01 1.82 1.67 1.54 1.26 1.07 0.94 0.83 0.75 5 5.33 4.29 3.62 3.14 2.79 2.52 2.30 2.12 1.96 1.63 1.40 1.23 1.10 1.00 10 6.04 4.91 4.18 3.66 3.26 2.96 2.71 2.51 2.34 1.96 1.69 1.50 1.35 1.23 25 6.78 5.49 4.68 4.11 3.69 3.36 3.10 2.88 2.70 2.28 2.00 1.79 1.63 1.50 0 50 7.37 5.96 5.09 4.49 4.04 3.70 3.42 3.19 3.00 2.56 2.26 2.04 1.87 1.73 CA 1001 8.08 6.49 5.56 4.92 4.46 4.10 3.81 3.57 3.37 2.92 2.61 2.37 2.19 2.04 Table based on VDOT Hydraulic Design Advisory HAD 05-03 If = B / (% + D)E where: If = Rainfall intensity for a given recurrence interval, f, in inches per hour t� = Watershed time of concentration (assumed to equal the storm duration), in minutes B,D,E = As taken from HDA 05-03 table for [Roanoke] [Roanoke (city)] based on the designated storm frequency. COUNTY OF ROANOKE 7444k/1/16 4C-2 STORMWATER HYDROLOGY OPEN CHANNELS Chapter 5 — Open Channels CHAPTER 5 Open channels are man-made ditches and channels and natural channels, that are used to convey stormwater flow. This section defines criteria and restrictions to be used in designing open channels. Where open channels are a part of a BMP, they shall comply with the state requirements for the purposes of water quality improvement; however, they shall also comply with this Design Manual's requirements for water conveyance. 5.1 References The primary design references are: • VDOT Drainage Manual • VDOT Specifications • VA E&SC Handbook • Hydraulic Engineering Circular Number 15 (HEC -15), Design of Roadside Channels with Flexible Linings, Current Edition, as amended • VA SWM Handbook 5.2 Design Methodology and Criteria 5.2.1 Major and Minor Manmade Open Channels A major channel is designed to convey less frequent storm events which would have significant adverse consequences if it failed. Major channels protect buildings and other important features from flooding and catastrophic failures. A minor channel is designed to convey more frequent storm events and they include most onsite open channels and roadside ditches. These structures have less adverse consequences due to overtopping. 5.2.2 Design Flow Design flow for manmade open channels within a development is contained in Chapter 4.2.2. Channels shall be designed to convey the 10 -year flow. Additionally, all storm drainage designs for open channels, culverts, and storm drains shall be checked for the 100 -year flow condition where there is the possibility of flooding residences, commercial or industrial buildings, overtopping primary roads, experiencing significant economic loss, or catastrophic failure. Where justified by the consequences of failure, the minimum design frequency COUNTY OF ROANOKE 7444x/1/16 5-1 OPEN CHANNELS OPEN CHANNELS CHAPTER 5 shall be increased. Design flows for downstream channels and all natural channels shall comply with the VA SWM Regulations. 5.2.3 Hydrology See Chapter 4 for methodology used to determine peak flows for a given design frequency. 5.2.4 Channel Hydraulics Open channel design will be based on Manning's Equation for open channel flow, unless good engineering practice dictates using HEC -RAS or other method. See the VA SWM Handbook and VDOT Drainage Manual, as appropriate. Q= A x 1.49/n x Rz/' x Slit Where: Q = Flow in the open channel (cfs) A = Cross-section area of the channel (ft) R = A/wetted perimeter (ft) S = Channel slope (ft/ft) n = Channel roughness coefficient Nomographs have been included in Appendix 5A for use in solving Manning's equation setting channel characteristics. 5.2.5 Channel Velocity The lining of minor channels with drainage areas of five acres and less shall be designed to withstand the erosive effects of a 2 -year storm. The lining of minor channels with drainage areas over five acres and major channels shall be designed to withstand the erosive effects of a 10 -year storm. The final design shall be consistent with velocity limitations for the selected channel lining, as presented in Table 5-1. Major channels associated with dam embankment spillways or other structures where catastrophic failure could result from a lining failure may be required to be designed to withstand a more severe storm event. Where open channels receive flow from storm drains, culverts, or other open channels, or in other areas where channel velocity may cause scouring or erosion, outlet protection or energy dissipation may be necessary to reduce the potential for severe erosion. For the design of energy dissipation devices, see Chapter 10. COUNTY OF ROANOKE 7444x/1/16 5-2 OPEN CHANNELS OPEN CHANNELS TABLE 5-1 Maximum Velocity Based on Channel Lining CHAPTER 5 Channel Lining Maximum Velocity (Design Storm) Erosion Resistant Easily Erodible Soils Soils Vegetative Lined Channels Tall Fescue Grass Mixtures 6 fps 4 fps Kentucky Bluegrass 6 fps 4 fps Annual and Perennial Rye 4 fps 3 fps Sod 4 fps 3 fps Geos nthetic LinqA VDOT EC -2 4 fps VDOT EC -3, Type I f s VDOT EC -3, 10 fps Other Per Mfr Recommendations Riprap (see VDOT Drainage Manual Appendix 7-D for n valuesl Dependent on stone size and thickness, see HEC -15 for design of riprap channels Concrete None 1 Erosion resistant soils include those with a high clay content and high plasticity, silty clay, sandy clay, and clay. 2 Easily erodible soils include those with a high content of fine sand or silty, lower plasticity or non -plastic, sand, silt, sandy loam, and silty loam with an erodibility factor (K) greater than 0.35. 3Soils shall be presumed to be easily erodible; unless a geotechnical investigation is performed that samples and tests the soils. 4All channels constructed in fills shall be considered to be in easily erodible soils. 5.2.6 Channel Slope Generally the channel slope shall be established by the site topography. Open channels must be graded to drain with no standing water following a rain event. The minimum allowable grade shall generally be 2 percent for vegetated -lined and riprap-lined open channels and 1 percent for a concrete open channel. The maximum allowable grade for a stormwater channel shall be dependent on the channel lining materials and its ability to withstand erosion during the design storm. COUNTY OF ROANOKE 7444x/1/16 5-3 OPEN CHANNELS OPEN CHANNELS 5.2.7 Cross Sectional Area CHAPTER 5 Open channel cross-section area shall be designed based on site restrictions and channel capacity requirements. The following information as a minimum shall be - , - Formatted: Highlight provided. in either a table and/or detail on the design plans that includes the - Formatted: Highlight channel number if multiple swales are proposed, bottom width, top width, slope, - Formatted: Highlight side slopes, total depth including freeboard, and liner. Each swale should be Formatted: Highlight included in the chart and not just a worst case scenario. Additionally, Off, Qjo water depth, freeboard provided, and Vshall be clearly ..- - Formatted: Subscript indicated in the calculations. Formatted: Subscript Formatted: SubscriptAcceptable cross-sectional area options include: • Vee • Parabolic • Trapezoidal Rectangular - - Formatted: List Paragraph, No bullets or numbering, Tab • Yard stops: Not at 1.5' ---------------------------------------------- Formatted: Highlight A. `Vee - - - - - --------------------------------------- Formatted: Font: Bold For design aids, see the VDOT Drainage Manual and the VA E&SC Handbook. Additionally computer software such as North American Green, Flowmaster, etc. can be used for design aids. The maximum side slope of a vee -shape open channel is 3 horizontal to ] vertical for vegetated channels (including reinforced vegetated) and is 2 horizontal to 1 vertical for all other linings engineered to be stable at this slope. B. farabolic ------------------------------------------ -- Formatted: Font: Bold For design aids, see the VDOT Drainage Manual and the VA E&SC Handbook. Additionally computer software such as North American Green, Flowmaster, etc can be used for design aids. COUNTY OF ROANOIKE 7444x/1/16 5-4 OPEN CHANNELS OPEN CHANNELS CHAPTER 5 C._ Trapezoidal Formatted: Font: Bold For design aids, see the VDOT Drainage Manual and the VA E&SC Handbook. Additionally computer software such as North American Green, Flowmaster, etc. can be used for design aids. The maximum side slope of a trapezoidal -shape open channel is 3 horizontal to 1 vertical for vegetated channels (Including reinforced vegetated) and is 2 horizontal to 1 vertical for all other linings engineered to be stable at this slope. P._ _ _ Rectangular ......... Formatted: Font: Bold Rectangular channels shall only be allowed where site restrictions prevent the installation of a vee, parabolic, or trapezoidal channel. The requirements for rectangular channels apply to any open channel with side slopes greater than 2 horizontal to 1 vertical. Rectangular channels must either be concrete or gabions. An approved safety barrier must be placed on both sides for the length of the rectangular channel, where the channel is more than 3 -feet deep. Care must be taken to ensure that energy dissipation is placed at the outfall of the rectangular channel to prevent erosion at the discharge point. E. Yard Yard swales what do not convey stormwater over multiple lots can utilize a basic yard swale detail*without providing calculations if the following- conditions are met: less than 0.25 acres drainage area, 2.0% minimum _ longitudinal slope, 6% maximum longitudinal slope, side slope of 4:1 H:V (maximum 3: 1), bottom width of 0 feet, total depth of 1.1 applicable to width based on side slopes, and type of liner labeled (i.e.rg ass). The Designer shall show a detail on the plan that meets the basic yard swale ` criteria. All other yard swal ;s will required calculations and an applicable detail. Yard swales must Aave a grass liner. COUNTY OF ROANOKE 7444x/1/16 5-5 OPEN CHANNELS Formatted: Font: Bold Formatted: Indent: Left: 1", Hanging: 0.5" Formatted: Not Highlight Formatted, Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight Formatted: Not Highlight OPEN CHANNELS 5.2.8 Channel Lining CHAPTER 5 An open channel lining shall be designed based on the cross-section, slope, and channel velocity requirements. The design may be based on a consideration of either permissive velocity or tractive force as described in the VDOT Drainage Manual. The preferred method for analyzing channel linings is to compare the maximum permissible velocity for the channel lining, listed in Table 5.1 in this chapter of the Design Manual, to the design velocity computed using Manning's equation to verify that the selected lining is adequate. As an alternative, the selected lining may be analyzed using the Tractive Force Method published in the VDOT Drainage Manual. This method analyzes sediment critical shear loading on the open channel bottom and side slope. The permissible tractive force for various soils is located in the Appendix of the VDOT Drainage Manual. Open channels may have different lining materials in different channel reaches based on velocity and potential erosion conditions. Care must be exercised to avoid erosion at open channel transition points. The open channel lining will have an impact on the design capacity in the form of the roughness coefficient. A table of generally accepted roughness coefficient (n) for various channels and linings is included in Appendix 5A. Allowable open channel linings include the following: A. Natural ----------------------------------------- Formatted: Font: Bold To the maximum extent possible, natural channels shall be preserved. Design discharges from permitted land disturbing activities shall comply with the VA SWM Regulations. J1 _ _ Vegetative -Lined _ _" Formatted: Font: Bold Vegetated or grass -lined channels include man made channels lined with established vegetation. These channels usually include a geosynthetic mat for channel stabilization. The type of grass allowable for vegetative -lined open channels is dependant on the slope of the channel, and the peak calculated velocity. Table 5-1 details the maximum permissible velocities for various channel linings. COUNTY OF ROANOIKE 7444x/1/16 5-6 OPEN CHANNELS OPEN CHANNELS CHAPTER 5 A permanent channel stabilization geosynthetic mat should be considered for all vegetated channels. There are a wide variety of geosynthetic stabilization mat options from various manufacturers. The geosynthetic mat selected should be adequate for the slope and design flow velocities calculated for the channel. Where appropriate, VDOT Road and Bridge Standard EC -2 or EC -3 may be used. Where a permanent geosynthetic mat is used to provide channel stabilization, information on the proposed mat, in the form of manufacturer's catalog information, shall be submitted as a part of the stormwater management plan. The catalog information shall include the manufacturer's recommendations for maximum allowable velocity. Design drawings must state that the geosynthetic stabilization mat shall be installed in strict accordance with the manufacturer's recommendations. Where a permanent channel stabilization geosynthetic is not used, a temporary geosynthetic lining designed to provide a measure of bank stability until such time a reasonably stable and mature stand of vegetation is established shall be provided. C.- - - Riprap-Lined-------------------------------- _ Formatted: Font: Bold The use of vegetated and geosynthetic-lined open channels for gentle - sloped open channels and concrete for steep -sloped open channels is recommended. Riprap-lined channels will not be acceptable where vegetated or geosynthetic-lined open channels are feasible. However, where design flow velocities exceed the erosive capability of a natural or vegetative -lined channel, rip rap may be used as a channel liner in areas where erosion is a concern. For an extended length of high velocity channel, consideration should be given to using a concrete channel rather than rip rap. Riprap lining shall be properly embedded in accordance with VDOT standards to maintain intended ditch cross section. Where riprap is required due to velocity conditions, it shall meet VDOT Standards and VDOT Specifications. VDOT recommended 50 percent stone size (D5o) and weight (W5o) and recommended thickness (T) for various riprap classifications is included in Appendix 5A. J)._ - - Concrete -Lined Formatted: Font: Bold Reinforced concrete shall be considered where design velocities dictate or where there is a need to provide the maximum level of erosion protection. COUNTY OF ROANOKE 7444x/1/16 5-7 OPEN CHANNELS OPEN CHANNELS 5.2.9 Freeboard Requirements CHAPTER 5 Manmade channels within a development shall have a minimum of 6" of freeboard above the calculated water level during the design peak flow, unless flow is supercritical. Where flow is supercritical, a minimum of 12" of freeboard is required. Yard swales require 6" of freeboard._ Flow is supercritical when: _ _ _ - - I Formatted: Highlight V/(32.2xIT)05> 1 Where: V — velocity (fps) H — depth of flow (feet) At bends and curves, the freeboard shall be measured from the calculated water level, including the increased depth due to the superelevation of the water surface. 5.2.10 Calculation of Depth of Flow at Bends and Curves Increases in the depth of flow occur at bends and curves due to the superelevation of the water surface. Superelevation of the water surface at bends and curves is calculated by: AZ — Vz / (32.2 x r�) x (ro — ri) where AZ — difference in water surface elevation between the concave and convex banks (ft) V — average velocity (ft/s) r� — radius of the center of the stream at the bend (fl) ro — radius of the outside bank of the stream at the bend (ft) ri — radius of the inside bank of the stream at the bend (fl) The increase in the normal stream flow depth at the outer bank of an open channel bend is one half of AZ. 5.2.11 Channel Location and Width Restrictions on Residential Lots The tops of open channel banks shall be at least 20 -feet from a residence. Where manmade open channels collect stormwater from more than one lot and they are located on a residential zoned lot their use shall be restricted as follows. Where all requirements cannot be met, a closed pipe storm drain system is required. COUNTY OF ROANOKE 7444x/1/16 5-8 OPEN CHANNELS OPEN CHANNELS CHAPTER 5 • Residential lot size 1 acre or greater o No additional restrictions. • Residential lot size 0.5 acre or greater, but less than 1 acre o Open channel top width shall be a maximum of 15 feet o Maximum drainage area passing through the open channel shall be 5 acres. • Residential lot size less than 0.5 acre o Open channel top width shall be a maximum of 15 feet o Maximum drainage area passing through the open channel shall be 3 acres. The above restrictions do not apply if any one of the following conditions is present: • The open channel is a natural channel that has adequate capacity. The retention of natural channels is encouraged. • The open channel is a perennial or intermittent stream that has adequate capacity and will remain undisturbed. • It may be demonstrated that open channels are required as a part of an integrated design to obtain the necessary water quality treatment. 5.3 Environmental Considerations and Fishery Protection Construction or modifications to open channels shall comply with all applicable laws and regulations. The applicant is responsible for procuring all necessary permits, such as US Army Corps of Engineers and VA DEQ Wetland Permits, VA DEQ VPDES Permits, etc., prior to obtaining a Land Disturbance Permit. A copy of these permits shall be submitted to Roanoke County prior to scheduling the precon meeting or the Engineer shall submit a 3rd party report to the County that supports that the permits are not required. 5.4 Maintenance Requirements The permittee is responsible for maintenance of open channels until construction is complete, including final clean up and site stabilization, to the satisfaction of the County of Roanoke. After the completion of construction, the property owner is responsible for maintenance of open channels. Maintenance includes periodically pruning or mowing vegetation and removing debris. COUNTY OF ROANOKE 7444x/1/16 5-9 OPEN CHANNELS OPEN CHANNELS 5.5 Floodplain Studies CHAPTER 5 A floodplain study shall be performed for all drainage areas greater than 100 acres that do not have detailed FEMA Flood Insurance Study flood profiles or elevations. See Chapter 12 for additional information on floodplain requirements. COUNTY OF ROANOKE 7444x/1/16 5-10 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A AIDS FOR OPEN CHANNEL DESIGN FROM CHAPTER 7, VDOT DRAINAGE MANUAL Appendix 7B-1, LD -268, Roadside and Median Ditch Design Form Appendix 7B-3, Channel Stability Work Sheet APPENDIX 5A Appendix 7B-4, Riprap Design Work Sheet for Standard VDOT Riprap Sizes Only Appendix 7B-5, Riprap Design Work Sheet for other than VDOT Standard Riprap Sizes Appendix 7C-1, Nomograph for Solution of Manning's Equation Appendix 7C-2, Trapezoidal Channel Capacity Chart Appendix 7C-3, Nomograph for Solution of Normal Depth Appendix 7D-1, Values of Roughness Coefficient n, 2 sheets Appendix 7D-3, Standard VDOT Riprap Classifications, Weights, and Blanket Thickness Appendix 7D-5, Selection of Stability Factors Appendix 713-6, Permissible Velocities for Erodible Linings Appendix 7E-1, Angle of Repose of Riprap in Terms of Mean Size and Shape of Stone Appendix 7E-2, Permissible Shear Stress for Non -Cohesive Soils Appendix 7E-3, Permissible Shear Stress for Cohesive Soils Appendix 7E-4, Bank Angle Correction Factor (Ki) Nomograph Appendix 7E-5, Correction Factor for Riprap Size Appendix 7E-6, Riprap Size Relationship Appendix 7E-7, Channel Side Shear Stress to Bottom Shear Stress Ratio COUNTY OF ROANOKE 7444x/1/16 5A-1 OPEN CHANNELS OPEN CHANNELS Appendix 7E-8, Tractive Force Ratio (K2) Appendix 7E-9, Determination of Mean Spherical Diameter COUNTY OF ROANOKE 7444x/1/16 5A-2 APPENDIX 5A OPEN CHANNELS OPEN CHANNELS APPENDIX 5A COUNTY OFROANOKE 7444x/1/16 5A-3 OPEN CHANNELS OPEN CHANNELS CHANNEL STABILITY WORKSHEET CHANNEL DATA Q = WS) P = (ft-) So _ (ft!ft) R = (ft.) d. (R) '- (fpr,) A=--- ,(ftp) Sine Slope = ;1 STABILITY OF NATIVE MATERIAL 70= 62,4+ R • Sa K, 11 - (sir? 0 / sir? - 62.4. Tp Bed - (Appendix 7E-2 or 3) For D5c= _ ° (Appendix 7E-1) For D7s = _ ° (Appendix 7E-9) Side Slope = _ = A 0=— K,=[1-(sir?9/sir? ]l 0.5 Ki = [1- (sir? / sir's ,)] 15 = Ts Side Slope (SS) = Tp Bed K = TP Bed ( ) (<) (=) (>) T. ( ) Native Material on Bed is (stable) (unstable) TS SS ( ) (<) (=) N to ( ) Native Materpal on Side Slope is (stable) (unstable) APPENDIX 5A Native Material D50 D75 _ n= COUNTY OF ROANOKE 71/14x/1/16 OPEN CHANNELS 5A-4 OPEN CHANNELS RIPRAP DESIGN WORKSHEET (VDOT STANDARD SIZES) CHANNEL DATA Q = (cfs) So - (ft/ft) d,, (ft.) A _ (ft -2) DETERMINE RIPRAP SIZE � = 42° Side Slope = P = -(t) R (ft.) V. (fps) Side Slope = 1 0= ° K, _ [1 - ($in2 0 f sin2F)] a,5 K, _ [1 - (sin2 �° f sine 42°)] ° 5 1 For Specific Gravity = 2.65 and Stability Factor - 1.2 f D60 O.001 • 3/ ( 4.5 1.) r1U APPENDIX 5A D$a Garnputed = Note: All VD07 standard riprap (Class Al through Type 11) is assumed to have a 0 of approximately 42° and a Specific Gravity of 2,65. Therefore, the Computed D50 should be adjusted by the Stability Correction Factor (CSF) (if any) to derive a Final Ds, The VDOT standard class sal Tipidp with ihu next higher D5a should bu spedr&d. Correction Factor For Stability Factor (SF) ether than 1.2 ([Default= 1.0) Csr - (SF 11.2)' 5 - ( 11 2)15 -- Final D54= C • Computed D5a = • RIPRAP RECOMMENDATION; VDOT (Class) (Type) Thickness (T) = " (2 • Dom, MSD minimum) COUNTY OF ROANOKE 74/14x/1/16 OPEN CHANNELS 5A-5 OPEN CHANNELS RIPRAP DESIGN WORKSHEET (NON—VDOT STANDARD SIZES) CHANNEL DATA Q = (rfs) P = (ft.) n = So = (ft/ t) R = (ft.) dfi= 00 V� (fp3) A= (ft) Side Slop: _ A ASSUMED RIPRAP SIZE - Dw = VERIFY ASSUMED RIPRAP SIZE APPENDIX 5A _ ° (Appendix 7E-11) Serle Slope - :1 O= ° K,=[1-(sin26/sine+))9'5 K, = [1 - (sing -0/sin e iI 0.5 = For Specific Gravity = 2.65 and Stability Factor = 1.2 tD, = 0.001 Va3 I (dam D' -K,') D5„ = D.DD1 • s 1 ( 0.5 , 1 sj = Deo Computed (_) (E) (=) (>) Dso Assumed ( ) Assumed Dso is (correct) (incorrect) Note= The above process of assuming a %, size, determining the natural angle of repose (0) and computing a D5o size should be repeated until the Assumed Dw size equals the Computed DSD size. Once the %,, size determination has been made, it should be adjusted for the Specific Gravity Correction Factor C, (if any) and the Stability Correction Factor (Cs,) (if any) to derive a Final D, Correction Factor For Riprap Specific Gravity (S3) other than 2.65 (Default = 1.4) C,=2.12/(% -1),.s = 2.121( - 1)1.s = Correction Factor For Stability Factor (SF) other than 1.2 (Defauk = 1.0) CSF = (SF 1 1.2)'.s = ( / 1.2)' 6 = Final Correction Factor = C = C.9 ■ C' = _ Final D..= C +Computed D RIPRAP RECOMMENDATION' Thickness (T) = " (2 • D60 MSD minimum) COUNTY OF ROANOKE 7444x/1/16 5A-6 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A NOMOGRAPH FOR SOLUTION OF MANNINGS EQUATION G9+R � noCid h � Al .e } LA 6 COUNTY OFROANOKE 7444x/1/16 5A-7 an 4 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A TRAPEZOIDAL CHANNEL CAPACITY CHART 11 II u n rl N C7 N ^ 4 d O Q 4 ]n 8 COUNTY OFROANOKE 7444x/1/16 5A-8 m ci OPEN CHANNELS OPEN CHANNELS APPENDIX 5A NOMOGRAPH FOR SOLUTION OF NORMAL DEPTH d NSTE= Fa a wlzmlal lY f w Z.0 *r h y Q to oMofn vwkm for 2 = 1 10 a r+ m ,r m 4.P d 1 S SUW I POM `57.1 On 0.08 (FT 3,(S) 0,06 2 ❑ C7A5 SL574 -10 Ld 0.ca ®-4 J FZ t7 S.d d_04 V Z 3,0 t— 0.002 cz Ota •n.rt 9A@ O.Ofi SL9� 4.513 AFF) j EXAMPLE: "0 VVEh: FIND. SUW I POM S-0.01 d Gaa0.3 9=1Q FT3/s 00.0.14 a. U.03 d=4.1444)=O56 ET 8-4 FT Z-4 1 4.2 O.® 1.0 COUNTY OF ROANOKE 74/14x/1/16 OPEN CHANNELS 5A-9 OPEN CHANNELS APPENDIX 5A VALUES OF ROUGHNESS COEFFICIENT `n' CHANNELS Type of Channel and Description Minimum Normal Maximum LINED CHANNELS (Selected linings) a. Concrete 1. Trowel finish 0.011 0.013 0.015 2. Float finish 0.013 0.015 0.016 3. Gunite, good section 0.016 0.019 0.023 b. Asphalt 1. Smooth 0.013 0.013 --- 2. Rough 0.016 0.016 --- EXCAVATED OR DREDGED a. Earth, straight and uniform 1. Clean, recently completed 0.016 0.018 0.020 2. Clean, after weathering 0.018 0.022 0.025 3. Gravel, uniform section, clean 0.022 0.025 0.030 4. With short grass, few weeds 0.022 0.027 0.033 b. Earth, winding and sluggish 1. No vegetation 0.023 0.025 0.030 2. Grass, some weeds 0.025 0.030 0.035 3. Dense weeds or aquatic plants in deep channels 0.030 0.035 0.040 4. Earth bottom and rubble sides 0.025 0.030 0.035 5. Stony bottom and weedy sides 0.025 0.035 0.045 6. Cobble bottom and clean sides 0.030 0.040 0.050 c. Dragline excavated or dredged 1. No vegetation 0.025 0.028 0.033 2. Light brush on banks 0.035 0.050 0.060 d. Rock cuts 1. Smooth and uniform 0.025 0.035 0.040 2. Jagged and irregular 0.035 0.040 0.050 e. Channels not maintained, weeds and brush uncut 1. Dense weeds, high as flow depth 0.050 0.080 0.120 2. Clean bottom, brush on sides 0.040 0.050 0.080 3. Same, highest stage of flow 0.045 0.070 0.110 4. Dense brush, high stage 1 0.080 1 0.100 1 0.140 COUNTY OF ROANOKE 7/1/14x/1/16 5A-10 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A VALUES OF ROUGHNESS COEFFICIENT `n' NATURAL STREAMS Type of Channel and Description Minimum Normal Maximum NATURAL STREAMS 1. Minor streams (top width at flood stage <100 ft) a. Streams on Plain 1. Clean, straight, full stage, no rifts or deep pools 0.025 0.030 0.033 2. Same as above, more stones and weeds 0.030 0.035 0.040 3. Clean, winding, some pools/shoals 0.033 0.040 0.045 4. Same as above, but some weeds and stones 0.035 0.045 0.050 5. Same as above, lower stages, more ineffective 0.040 0.048 0.055 slopes and sections 6. Same as 4, but more stones 0.045 0.050 0.060 7. Sluggish reaches, weedy, deep pools 0.050 0.070 0.080 8. Very reedy reaches, deep pools or floodways 0.075 0.100 0.150 with heavy stand of timber and underbrush b. Mountain Streams (no vegetation in channel, banks usually steep, trees and brush along banks submerged at high stages) 1. Bottom: gravels, cobbles, few boulders 0.030 0.040 0.050 2. Bottom: cobbles with large boulders 0.040 0.050 0.070 2. Floodplain a. Pasture, no brush 1. Short grass 0.025 0.030 0.035 2. High grass 0.030 0.035 0.050 b. Cultivated area 1. No crop 0.020 0.030 0.040 2. Mature row crops 0.025 0.035 0.045 3. Mature field crops 0.030 0.040 0.050 c. Brush 1. Scattered brush, heavy weeds 0.035 0.050 0.070 2. Light brush and trees, in winter 0.035 0.050 0.060 3. Light brush and trees, in summer 0.040 0.060 0.080 4. Medium to dense brush, in winter 0.045 0.070 0.110 5. Medium to dense brush, in summer 0.070 0.100 0.160 d. Trees 1. Dense willows, summer, straight 0.110 0.150 0.200 2. Cleared land with tree stumps, no sprouts 0.030 0.040 0.050 3. Same as above, but with heavy sprout growth 0.050 0.060 0.080 4. Heavy stand of timber, a few down trees, little 0.080 0.100 0.120 undergrowth, flood stage below branches 5. Same as above, but with flood stage reaching 0.100 0.120 0.160 branches 3. Major Streams (top width at flood stage > 100 ft) a. Regular section with no boulders or brush 0.025 --- 0.060 b. Irregular and rough section 0.035 --- 0.100 (The n value is less than that for minor streams of the same description, because banks offer less effective resistance.) COUNTY OF ROANOKE 7/1/14x/1/16 5A-11 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A STANDARD VDOT RIPRAP CLASSIFICATIONS, WEIGHTS, AND BLANKET THICKNESS Classification D50 (ft) W50 (lbs) T (in) Class Al 0.8 50 20 Class I 1.1 100 26 Class II 1.6 300 38 Class III 2.2 1000 53 Type I 2.8 2000 60 Type II 4.5 8000 97 SELECTION OF STABILITY FACTORS Condition Stability Factor Range Uniform flow; straight or mildly curving reach (curve radius/channel 1.0- 1.2 width >30); impact from wave action and floating debris is minimal; little or no uncertainty in design parameters. Gradually varying flow; moderate bend curvature (30 > curve 1.3 - 1.6 radius/channel width > 10); impact from waves or floating debris is moderate. Approaching rapidly varying flow; sharp bend curvature (30 > curve 1.6-2.0 radius/channel > 10); significant impact from floating debris and/or ice, significant wind and/or bore generated waves (1-2 feet); high flow turbulence; mixing flow at bridge abutments; significant amount of uncertainty in design parameters. Channel bends when ratio of curve radius to channel width (R/W) > 30. 1.2 Channel bends when 30 > R/W > 10. 1.3- 1.6 Channel bends when R/W < 10. 1.7 COUNTY OF ROANOKE 7444x/1/16 5A-12 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A PERMISSIBLE VELOCITIES FOR ERODIBLE LININGS Soil type or lining (earth; no vegetation Maximum permissible velocities ft/sec for Water Water carrying Clear carrying sand and water fine silts gravel Fine sand (non colloidal) 1.5 2.5 1.5 Sandy loam (non colloidal) 1.7 2.5 2.0 Silt loam (non colloidal) 2.0 3.0 2.0 Ordinary firm loam 2.5 3.5 2.2 Volcanic ash 2.5 3.5 2.7 Fine gravel 2.5 5.0 3.7 Stiff clay (very colloidal) 3.7 5.0 3.0 Graded, loam to cobbles (non colloidal) 3.7 5.0 5.0 Graded, silt to cobbles (colloidal) 4.0 5.5 5.0 Alluvial silts (non colloidal) 2.0 3.5 2.0 Alluvial silts (colloidal) 3.7 5.0 3.0 Coarse gravel (non colloidal) 4.0 6.0 6.5 Cobbles and shingles 5.0 5.5 6.5 Shales and hard pans 6.0 6.0 5.0 COUNTY OF ROANOKE 7444x/1/16 5A-13 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A ANGLE OF REPOSE OF RIPRAP IN TERMS OF MEAN SIZE AND SHAPE OF STONE MEAN STONE SIZE, ❑S0, FT. 6 8 s i9 2Q 3a 44 Sa 80 lug 29G 300 41m Bao COUNTY OF ROANOKE 7444x/1/16 MEjkN STONE SIZE, 050.mu,r 5A-14 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A PERMISSIBLE SHEAR STRESS FOR NON -COHESIVE SOILS COUNTY OF ROANOKE 7/1/14x/1/16 )o PA€?TICLF- 01AMETER, 1) (mrn) 5A-15 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A PERMISSIBLE SHEAR STRESS FOR COHESIVE SOILS t_e 4.5 '% 0.1 lb/112 0.06 0.DI COUNTY OF ROANOKE 7444x/1/16 Chart 2 a_a o6.4 #4.0 P1,ASTl-v ITY INDEX — PA. 5A-16 OPEN CHANNELS HIM ME ME SPA, MEN a_a o6.4 #4.0 P1,ASTl-v ITY INDEX — PA. 5A-16 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A BANK ANGLE CORRECTION FACTOR (Ki) NOMOGRAPH 1 741/14X11/16 o Ki - sin sin = Bank angle w-th horizontal m . Material angle of repose (See chart 4) () M 0 M 35 34 1.5,1 K1 .10 34 za .30 2:1 so 25 1 .7Q35 -- . 2i1 ^" 40, 3.5:1_L �a Example Given: Find: Solution; C, 'O186 K o .-c YCF Vary Angular � K1= 0.885 DSO= 1,5 ft. 5A-17 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A CORRECTION FACTOR FOR RIPRAP SIZE C = i.6i SFI-11(Ss -1),.3 C _ D 5q CORRI70ION FACTOR SF = STABILITY FACTOR Ss= SPE=CIFIC GRAVITY OF ROCK Ss c SF 54 2.4 2,0 4.0} 1.9 2-1 1.8 3,0- 22 1,7 25 1,6 2.5- .32,(Y 2.0-- - 1.5 1.5 2-# y S 1.4 2,5- 1.3 2.B 2.0 2.7- .72'5 2.5- 2.9- 2.83.4 3,0 1.0 Q.� Example: Given_ Soluflo : Ss 2.65 C=1-0 SF = 1.2 COUNTY OF ROANOKE 74/44x/1/16 5A-18 OPEN CHANNELS OPEN CHANNELS APPENDIX 5A RIPRAP SIZE RELATIONSHIP D . 7 offLrm R.wikp Sato ( a Vs - Averapo valapty 4n main r}n mc4 tA1rAc} d mg- Average depm In maLi camel (M D 5d K, _ Eank angle mnjK4on wm 02 020 r dam y' Of 40as f° OA r 20 a0 r �JO r 2S- 15 r s 20 r {� 1.0 75 10 .4 10 6 4 W 3 4 EXRMp 13 {3hren: Fndi K, � d-73 1 741/14XI1/16 5A-19 WLIUD& 0 M .4 13 OPEN CHANNELS Co] W a1lzra me OO of R COUNTY OF ROANOKE 7444x/1/16 5A-20 APPENDIX 5A 51DE SLOPE 1141 P3 �2 10 OPEN CHANNELS OPEN CHANNELS 45 40 E d a � e w W 20 0 ww W 15 r9 iJ Y TRACTIVE FORCE RATIO (K2) APPENDIX 5A Chart 14 WousisLe-i -.. I I m NEESE- J 0-2 OA D.6 0.8 1.Q COUNTY OFROANOKE 7444x/1/16 5A-21 KZ OPEN CHANNELS OPEN CHANNELS APPENDIX 5A DETERMINATION OF MEAN SPHERICAL DIAMETER 10, 011D b ilk c: NIS 2.92 2.56 2.24 $_7B L.51 1,32 1 COUNTY OFROANOKE 74/14x/1/16 OPEN CHANNELS 5A-22 CULVERTS Chapter 6 - Culverts CHAPTER 6 A culvert is a single run of storm drain pipe that conveys water or stormwater under a road, railway, embankment, sidewalk, or other obstruction. A culvert typically connects two open channels, but they may connect an open channel to a storm drain. Proper culvert design must consider many factors including: • Design Flow • Inlet conditions (flow approach conditions, allowable headwater, culvert inlet configuration) • Culvert conditions (material roughness, pipe slope, and length) • Tailwater depth • Buoyancy potential • Environmental considerations and effects on aquatic life • Design loads and service life of the pipe material Refer to the VDOT Drainage Manual, for a more through discussion of these items. For the design of stormwater inlets and storm drains, see Chapter 7. 6.1 References Except where more stringent requirements are presented in this Design Manual, culverts shall comply with VDOT requirements. The primary design reference is the VDOT Drainage Manual. Other appropriate references include: • VDOT Standards • VDOT Specifications • VA E&SC Handbook • VDOT Instructional and Informational Memorandum IIM-1D-121.15, Allowable Pipe Criteria for Culverts and Storm Sewers • FHWA Hydraulic Design of Highway Culverts HDS No. 5, Pub. No. FHWA- NHI-01-020, Current Edition, as amended • FHWA Debris Control Structures Evaluation and Countermeasures HEC No. 9, Pub. No. FHWA-IF-04-016, Current Edition, as amended COUNTY OF ROANOKE ;444x/1/16 6-1 CULVERTS CULVERTS CHAPTER 6.2 Design Methodology and Criteria 6.2.1 Computation Methods Manual computations use design equations and nomographs. Results are documented on VDOT's Design Form LD -269. Form LD -269 is included in Appendix 6A. There are a number of computer programs available to design culverts. Any of these computer programs will be acceptable if their methodologies are based on the same equations and nomographs accepted by VDOT, and if they provide the same documentation of inputs, assumptions, and output as are contained on VDOT's Design Form LD -269. 6.2.2 Hydrology �1. Design Flow Methodology Formatted: Font: Bold See Chapter 4 for methodology used to determine design flows. Generally culverts shall be designed based on the peak flow (steady state), ignoring the effects of temporary upstream storage. �. Obstruction Allowance Formatted: Font: Bold An obstruction allowance shall be applied in critical areas where excessive backwater may result in property damage or be a potential safety hazard. After using the appropriate design methodology to calculate the peak stormwater flow for a given frequency, an obstruction allowance will be added to the peak flow to establish the design flow rate through the culvert. The minimum obstruction allowance factor is intended to account for normal culvert obstructions, which may lower the actual capacity of the culvert once constructed, and is based on the size of the culvert pipe in accordance with the following tabulation: Culvert Size Minimum Obstruction Allowance Factor 18" and less 25% 21"-24" 20% 30" 15% 36" and greater 10% COUNTY OF ROANOKE ;444x/1/16 6-2 CULVERTS CULVERTS 6.2.3 Culvert Hydraulics CHAPTER 6 ,A._ Design Flow Formatted: Font: Bold The design flow shall be the peak flow from the following frequency storm event, plus the appropriate obstruction allowance: Roadway Storm Frequency Primary & Arterial 25 -year Secondary & Other 10 -year These frequencies are minimum values. Designing for less frequent storms may be required where there is potential damage to structures, loss of human life, injury, or heavy financial loss in the event of flooding. Compliance with the National Flood Insurance Program (NFIP) is necessary for all locations where construction will encroach on a 100 -year frequency flood plain. In addition, the 100 -year peak flow (without the addition of the obstruction allowance) shall be routed through all culverts, determining the headwater depth behind the culvert with road overtopping, to ensure that buildings and other structures are not flooded and that adjacent roadways and adjacent properties do not suffer significantly increased damage during the 100 -year storm event. Storage impacts of water behind the culvert may be considered in the calculation, but is not required. - - Formatted: Indent: Left: 1.5", First line: 0.5" ._Allowable Headwater Formatted: Font: Bold The allowable headwater is the depth of water that can be ponded at the upstream end of the culvert during the design condition, as measured from the culvert inlet invert. The allowable headwater depth shall be limited by the following conditions: • Headwater does not cause upstream property damage; • Headwater does not increase the 100 -year flood elevation, as mapped by NFIP; • During a design storm event, the water surface shall be a minimum of 18 inches below the shoulder of the road at the point where the culvert crosses COUNTY OF ROANOKE ;444x/1/16 6-3 CULVERTS CULVERTS CHAPTER under, or the low point of the road grade where the water would overtop the road; • Headwater depth shall not exceed 1.5 times the diameter or height of the culvert barrel; • Headwater depth shall not be such that stormwater flows to other ditches or terrain, which permits the flow to divert around the culvert. • The maximum overtopping depths during an 100 -year storm event for various street classifications are as follows: Classification Max. Depth at Crown Max. Velocity Local 1 ft* 6 fps Collector 1 ft* 6 fps Arterial No Overflow No Overflow Highway No Overflow No Overflow * Street overflow during a 100 -year storm will not be allowed if the street is the only means of access for 40 or more residences. A variance to this requirement may be granted if the applicant shows that the connecting roads will be experiencing substantial overtopping during a 100 -year storm and that there is no benefit to enforcing this requirement. • In most instances, the roadway overtopping may be treated as a broad crested weir. ,C._ Tailwater Conditions Formatted: Font: Bold Tailwater is the water into which a culvert outfall discharges. Culvert design shall be based on tailwater conditions that could reasonably be anticipated during the design condition. • If an upstream culvert outlet is located near a downstream culvert inlet, the headwater elevation of the downstream culvert may establish the design tailwater depth at the upstream culvert. • If the culvert discharges into a lake, pond, stream, or other body of water, the maximum water elevation of the body of water during the design storm may establish the design tailwater elevation at the upstream culvert. COUNTY OF ROANOKE ;444x/1/16 6-4 CULVERTS CULVERTS CHAPTER Inlet and Outlet Control - Formatted: Font: Bold Culvert hvdraulic design shall consider both inlet and outlet control conditions. For a culvert operating with inlet control, the flow capacity is governed by the inlet geometry. For an outlet control culvert, the inlet geometrv. barrel characteristics and tailwater elevation all impact the flow capacity. Minimum culvert performance is determined by analyzing both inlet and outlet control for a given flow and using the highest resulting headwater. (i) Inlet Control - I Formatted: Underline The following factors are considered when calculating inlet control headwater: • Inlet Area — cross sectional area of the culvert entrance face • Inlet Edge — projecting, mitered, headwall, or beveled edges are common • Inlet Shape — rectangular, circular, elliptical, or arch are common The nomograph for inlet control for circular concrete, corrugated metal and corrugated HDPE culvert pipe is included in Appendix 6A. Nomographs for calculating headwater and flow capacity for other pipe geometries are contained in the VDOT Drainage Manual. ,(ii) Outlet Control - I Formatted: Underline The following factors are considered when calculating outlet control headwater: • Manning's Roughness (n) — based on barrel material, for recommended n values, see the table in Appendix 6A. • Barrel Area — cross section perpendicular to the flow • Barrel Length • Barrel Slope COUNTY OF ROANOKE ;444x/1/16 6-5 CULVERTS CULVERTS CHAPTER 6 • Tailwater Elevation Outlet control affects the hydraulic grade line of the flow through the culvert. To calculate the hydraulic grade, reference the equations for velocity, velocity head, entrance losses, friction losses, and exit losses contained in the VDOT Drainage Manual. The nomograph for outlet control on circular concrete and corrugated metal pipe is included in Appendix 6A. For additional nomographs, cross sections, and pipe materials, see the VDOT Drainage Manual. Formatted: Font: Bold E. Culvert Velocity Outlet velocity must be checked to assure that excessive erosion and scour problems will not occur. MS 19 from the VA E&SC Handbook requires that discharges be made to an adequate channel. Culvert outlet protection shall be provided in accordance with the standards and specifications for Outlet Protection and Riprap in the VA E&SC Handbook. Culverts under roads shall be provided with end sections or endwalls in accordance with the outlet protection requirements of the VDOT Drainage Manual. Where a special design is needed to reduce outlet velocity, it shall be designed in accordance with VDOT standards. The minimum velocity in a culvert barrel must be adequate to prevent siltation at low flow rates. At a minimum this velocity shall be 3 feet per second for a 2 -year storm event. 6.2.4 Structural Design All culverts shall be designed to withstand a HS -20 highway loading, unless it crosses under a railroad, in which case the culvert shall be designed for railroad loads. The structural design shall consider the depth of cover, trench width and condition, bedding type, backfill material, and compaction. 6.2.5 Materials Culverts, both public and private, shall be constructed of materials as follows: COUNTY OF ROANOKE ;444x/1/16 6-6 CULVERTS CULVERTS CHAPTER • Culverts in the VDOT right-of-way shall be VDOT approved materials in accordance with VDOT IIM-LD-121.15 and VDOT Standard PC -1. Minimum depths of cover are shown in the PC -1 details. • Public culverts not in the VDOT right-of-way shall be: o Reinforced concrete pipe (RCP) Class III minimum or greater as required by loading conditions/cover or box. o Aluminized corrugated metal pipe (CMP), is allowed for private systems only for sizes 36 -inch diameter or smaller. Minimum gage thickness for CMP culverts shall be 16 gage for 30 -inch diameter and smaller. Minimum gage thickness for 36 -inch diameter CMP culverts shall be 14 gage. Trench design for CMP culverts shall meet ASTM or AASHTO standards. o Special CMP culverts including diameters greater than 36 -inch, elliptical, and arch designs will be considered on a case-by-case basis by the County of Roanoke for use as culvert pipe material in private storm drain systems. • Private culverts not in the VDOT right-of-way may be: o Reinforced concrete pipe (RCP) Class III minimum or greater as required by loading conditions/cover or of box. o Aluminized corrugated metal pipe (CMP), for sizes 36 -inch diameter or smaller. Minimum gage thickness for CMP culverts shall be 16 gage for 30 -inch diameter and smaller. Minimum gage thickness for 36 -inch diameter CMP culverts shall be 14 gage. Trench design for CMP culverts shall meet ASTM or AASHTO standards. o Special CMP culverts including diameters greater than 36 -inch, elliptical, and arch designs will be considered on a case-by-case basis o Corrugated high-density polyethylene (HDPE) with an integrally formed smooth interior is allowed for sizes 48 -inch diameter or smaller. HDPE culvert pipe minimum cover must be in accordance with the County of Roanoke Inspection Specifications for HDPE Pipe contained in Chapter 7-13- 11. COUNTY OF ROANOKE ;444x/1/16 6-7 CULVERTS CULVERTS 6.2.6 Culvert Sizes CHAPTER 6 The minimum culvert size shall be 18 -inch diameter, except that culverts under private entrance roads or driveways may be 15 -inch diameter if it meets all design flow conditions. Culverts shall meet all cover conditions required. Where the site conditions preclude the use of a single culvert barrel to meet the design flow conditions, multiple barrel culverts are acceptable. The maximum length of a culvert shall be 300 feet. A culvert longer than 300 feet shall have manholes or junction boxes and shall fall under the requirements of Chapter 7. 6.2.7 End Conditions End sections and headwalls shall normally be required on inlets and outlets, as described below. �1. Prefabricated End Sections Formatted: Font: sold —Prefabricated end sections, or flared end sections, provide for a better flow path, improving the design flow and headwater conditions. Prefabricated end sections shall be provided for culverts 18 -inch to 36 -inch diameter, except: • No end section is required for 15 -inch or 18 -inch diameter driveway culverts. • Where culvert alignment exceeds 20 feet in vertical elevation change or culvert slope exceeds a 2:1 slope, a standard concrete headwall shall be provided instead of a prefabricated end section. • Where a concrete headwall is provided. J._ Concrete Headwalls and Structures - - I Formatted: Font: sold Precast concrete headwalls shall be provided at all culvert inlets and outlets, unless other end conditions are allowed, as stated above. Precast concrete headwalls shall meet the requirements of the VDOT Standards and VDOT Specifications. COUNTY OF ROANOKE ;444x/1/16 6-8 CULVERTS CULVERTS CHAPTER Wingwalls may be required in conjunction with headwalls. Culvert pipes 48" or larger in diameter shall have concrete wngwalls. Wingwalls are generally used where the culvert is skewed to the normal channel flow or where the side slopes of the channel or roadway are unstable. Wingwalls shall meet the requirements of the VDOT Standards and VDOT Specifications. Wing walls shall be set at an angle between 30 degrees and 60 degrees from the headwall. Concrete aprons may be used at the entrance or the exit of culvert. Aprons are typically used where high velocities or headwater conditions may cause erosion upstream or downstream of the culvert. An apron shall not protrude above the normal stream bed elevation. Special design concrete slab end treatment, per VDOT Standards, may be used as a concrete end section. 6.2.8 Multiple Barrel Culverts Multiple barrel culverts shall be allowed where single culverts cannot handle the design flow while meeting the required cover or headwater condition requirements. The design of multiple barrels should avoid the need for excessive widening of the upstream or downstream receiving channels. The minimum spacing between culverts in a multiple barrel culvert design shall be that required to provide adequate lateral support and allow proper compaction of bedding material under the pipe haunches. 6.2.9 Culvert Skew Where possible, culverts shall be installed parallel to the flow path. The maximum allowable skew shall be 45 degrees as measured from the line perpendicular to the roadway centerline. 6.2.10 Buoyancy Verify that culvert pipe, end sections, and concrete end wall structures will not fail under hydrostatic uplift conditions. Buoyancy force consists of the weight of water displaced by the pipe and fill material that is over the pipe (below the headwater depth). The force resisting buoyancy includes the weight of the pipe, weight of the water within the pipe, and the weight of fill material over the pipe. Buoyancy is more likely to be a problem where: COUNTY OF ROANOKE ;444x/1/16 6-9 CULVERTS CULVERTS CHAPTER 6 Lightweight pipe is used Pipe is on a steep slope (usually inlet control with the pipe flowing partially full) • There is little weight on the end of the pipe (flat embankment slopes, minimum cover, and/or no endwalls) • High headwater depths (HW/D>1.0) Suitable cover, footings, or anchor blocks may be required to ensure the culvert's integrity during design conditions. 6.2.11 Debris and Trash Racks In general, trash racks or debris deflectors shall not be used where other site modifications may be made to prevent excessive trash or debris from entering the culvert. However, they may be required at specific locations, by the County of Roanoke, where large amounts of storm debris may be anticipated. 6.3 Installation All culvert pipe, headwalls, end sections, outlets, and other peripheral structures shall be installed in accordance with VDOT requirements and the manufacturer's recommendations. The characteristics of the trench, bedding, and pipe material all impact the structural strength of the pipe system. The installed culvert conditions shall comply with the design assumptions and calculations. HDPE pipe installation shall comply with the County of Roanoke's Inspection Specifications for HDPE Pipe. A copy of this installation guide is provided in Chapter 7. 6.3.1 Bedding Material Bedding material and installation shall comply with the requirements of the VDOT Specifications. 6.3.2 Backfill Backfill shall be suitable material and shall be placed and compacted in accordance with VDOT Specifications. A minimum of 12" backfill shall be placed over the top of a HDPE or CMP .- - - Formatted: indent: Left: r', First line: 0" culvert prior to placing pavement or other surface treatment. COUNTY OF ROANOKE ;444x/1/16 6-10 CULVERTS CULVERTS CHAPTER 6.4 Environmental Considerations and Fishery Protection Where compatible with good hydraulic engineering, a culvert shall be located in "dry" conditions. Where this is not possible, the culvert shall be located to minimize impacts to streams or wetlands. When a culvert is set in a perennial stream the invert of the culvert shall be set below the normal flow line of the stream as required in the VDOT Drainage Manual. The grade of the culvert shall not exceed the grade of the natural stream in the area. Where construction requires other environmental permits, the applicant shall be responsible for obtaining all necessary environmental permits and complying with their requirements. 6.5 Maintenance Requirements The permittee is responsible for maintenance of culverts until construction is complete, including final clean up and site stabilization, to the satisfaction of the County of Roanoke. After the completion of construction, the property owner or responsible party is responsible for maintenance of all culverts not located in public easements. No one shall modify culverts in any way that impairs or restricts flow. The property owner shall periodically remove silt and sediment from the pipe and prune vegetation around the pipe entrance to avoid restricting flow capacity and shall correct erosion damage as necessary. All removed silt and sediment shall be properly disposed of away from storm drainage pipes and open channels and shall be properly stabilized with vegetation. COUNTY OF ROANOKE ;444x/1/16 6-11 CULVERTS CULVERTS APPENDIX 6A AIDS FOR STORMWATER CULVERT DESIGN FROM CHAPTER 8, VDOT DRAINAGE MANUAL APPENDIX 6A Appendix 813-1, Culvert Design Form LD -269 Appendix 8C-1, Nomograph for Inlet Control for Circular Concrete Pipe Appendix 8C-2, Nomograph for Inlet Control for Corrugated Metal Pipe Nomograph for Inlet Control for Corrugated HDPE Pipe Note: This table is not from the VDOT Drainage Manual. Appendix 8C-4, Nomograph for Critical Depth, Circular Pipe Appendix 8C-5, Nomograph for Outlet Control for Circular Concrete Pipe Appendix 8C-6, Nomograph for Outlet Control for Corrugated Metal Pipe Appendix 8D-1, Recommended Manning's n -Values Note: This table has been modified from VDOT's standard to include additional pipe materials. Appendix 8D-2, Entrance Loss Coefficients (Ke), Outlet Control, Full or Partly Full COUNTY OF ROANOKE ;444x/1/16 6A-1 CULVERTS CULVERTS APPENDIX 6A CULVERT DESIGN FORM (VDOT LD -269) COUNTY OF ROANOKE ;444x/1/16 6A-2 CULVERTS i LL 3■■0r n ■ .■.■�■■■■■� r■.■■■.■■■E �■■■ on • ■■■■E■.■■■■ I■■■■�■■ ■■■■■■■■■E .■■■.■■■■■.IMEMEMEMEMME [monsoon .■.■.■.■ ■■. 11,10MMEM ■®��■■ .mommmmommill ■■■.■■■■■. ..■..■■■■■. .. E■.■■■■■. IMEMBEEMEMER .■■.■■■■■■. .■■■■■■.■■.r ............ ■■■■■■■■■■�■■■■■� i-■■■■■■ MENOMONEE .■■ ■ ■■■■■■.. ■�■, MIME■■■■MINEENEEMBEE `■�■�■■.■ IMM■■■■■MINME■■�■■■.'. MM.■M■..l y ■■■.■■.., ......,l1 , - ■■■■■■.., . ■■■.■■A.. ■■■.■■EZ, 7 COUNTY OF ROANOKE ;444x/1/16 6A-2 CULVERTS CULVERTS Il` APPENDIX 6A TLET CONTROL, CIRCULAR CONCRETE PIPE CHART 1 Mo Me $r000 EXAMPLE {3} 666 p..! i.e■ae 144 ::m s.ao0 a req.h. }E 4,04q ■ * 6• S. 5.000 Ir.� .y 4. �eY ili S,3 i.�1 4. 2,001D 4.. X66 [tl9 t.t 7.h - 3. �4 Ip PNl �• 96 1 aU0 3. Boo 64 Baa --� -- - t- 900! it 400 !. 3b0 �." I,q Y.3 elp u Pca 1.0 z � �- 54 / = x 40 100 q Ba — r 42 —60 06 110 Fp W- EMTR AIi GE ca 40 4a SGALE TTPE tlt I-0 36 'Jq {11 sy..n.ra .er■ r 9 .$ S3 F.eex.p � ea .9 t'0 #I pram. ■r■.i�. W 30 e..■..0 ; .4 :4 tr .r■]Ie7W is 24 � 7. w. ■e■la lel •e p} h�l1.e� 41 S ■ne lea.+e!4 .a .s■M [15. ihp 4 ...Irel*hE farWny iY.. 1M.np pF.n1 0 iie..e•ar ray.rn a. 6 3 Wl..ir.1.4 .8 ]e r i6 1.0 .a B L Y4 HEADWATER DEPTH FOR rEkGWiRE11SCALES 2BB CONCRETE PIPE CULVERTS ■u.e.uww.LICWPM a.,w.OU aErisED MAY 934 WITH INLET CONTROL COUNTY OF ROANOKE ;/444x/1/16 6A-3 CULVERTS CULVERTS APPENDIX 6A INLET CONTROL, CIRCULAR CORRUGATED METAL PIPE 0 CHART 2 Ie9 X0,400 Is! 8,000 EXAMPLE II) ISB 6,994 m• Si l s... [e.a fNfl 6 ILl '5,000 a•44.H 144 4,000 r R MR 13@ 3,000 0-46 4. Ito i11 I,f f.4 -2,000 m ioe tel !.s 6.0 4• 4. 96 1,009 3. T3 000 S. 1 e4 q 600 1400 S90 1{ 7E . 300 is 800 4 60 h I W � 54 Q W � W 140 l S 7 40 c 60� O J 0, 60 x 42 60 l.0 I.0 -�N a � 40 y4j i.0 F 36 30 1!W ENTFCAN9E ¢ W p SCALE TYPE La o 33 29 N4.d.N1 30 121 Mil.nd to 0..10'.e � ,e I. M.P. ra 87 14 4'+I 1`16146o1.f a e a 84 F 6 .7 w 3 fp un mtr 12) w (31 rm}..r @i T' .e 4 ..n ... t.rlr t. s.4l. I,}, I►.n rM rU.14h1 in Glln4d Ilrr t.r..'k •6 ] 0 ..d 0 re.lr., tr ..'I.eN rl 6 iii nir.r..l.d. Z l 1,9 S HEADWATER DEPTH FOR C. M. PIPE CULVERTS WITH INLET CONTROL WPEAU W Pu9Ll 11 A03 -41"5 COUNTY OF ROANOKE ;444x/1/16 6A-4 CULVERTS CULVERTS APPENDIX 6A INLET CONTROL, CIRCULAR HDPE PIPE COUNTY OF ROANOKE ;444x/1/16 6A-5 CULVERTS �c_ard� t�} 6. 4. D- 36Artles'30feel) 6 44,000HOr C] 4, - 66 CIS HW 5 3J ,49318 D (leer) 200 i1 1.3 5.4 (2) 2:' 6.3 4 ,3) 22 6.6 3 a 1=0 .D in t£!Qt � BOO 3 540 S�41 4DO S 2 T ' __ EXAMPLE 1,5uj 54 cc 48 UlToo '.. /� cd L 7� C' 'te Hier d =u'GALe 40 D Tv / { /}} i��. dEvmp 11 f 3 # 30 . . # {2} MOlare d to 33 20 cmfarm to slope Lu 08 0. 3 � l31 i�rrsj�etin� � p 4.#3 L U_7' 43.2 24 = g p_7 3Ta use scale i2l ;2lOr 3) prajacl x, e. hotizovla!ly to stela � t ), thel use straight inclined lime th•augh 6.6 18 D and 0 =a!ec, or revarse as 2 itusttal. is 4 ry 10 U.5 HEADWATER DEPTH FOR e2 CORRUGATED HDPE CULVERTS WITH INLET CONTROL COUNTY OF ROANOKE ;444x/1/16 6A-5 CULVERTS CULVERTS CRITCAL DEPTH, CIRCULAR PIPE CHART 4 9 r w W x 6 W 6 J Y 61 APPENDIX 6A '.I I I i I I do CAMNQT ixMID Tor W P5t x 9 �4 912 39 dko 50 60 70 00 •G 11212 41§CFliTiGE• 9 - GF9 w W O r r YI O J d �4 �i}0 204 'J9G 49D 5129 699 F912 499 999 F9nC 615CNARCE -9-OF S a] r ■■MENo N■NEM■i■■■■■o s• ■■■■■ DISCHARGE - 9. GFS BUREAU Of PUML14 ROADS DAPI. 194i4 CRITICAL DEPTH CIRCULAR PIPE COUNTY OFROANOKE ;444x/1/16 6A-6 CULVERTS CULVERTS APPENDIX 6A OUTLET CONTROL, CIRCULAR CONCRETE PIPE 7 2404 nw I CCpO C = J 511l LR�GiG OYi LlT 04eyENT FtAwni ryL� .S Y00 YR4 f�r w+err �r rol •Ly/� I+weUM Y N �' lw�N SU4 '36 F yam' l9 400 $04 - T! 2 800 60 4fi W - W 9 �r—'�.`�— ti z 3 cy IOO T Ll i ±t + �•� a yp ry -4 moll 9 1- A $ d 0 40 W bQ txp' a • Q .l 10 20 tl 120 Ya 0 ES Y g Y9 9 4 hEAD FOR CONCRET1= PIPE CULVERTS FLOWING FULL WA -0f O-LSLIC F&*DS 4++1. per} n m 0 0 12 COUNTY OFROANOKE ;444x/1/16 6A-7 CULVERTS CULVERTS APPENDIX 6A OUTLET CONTROL, CIRCULAR CORRUGATED METAL PIPE r 2000 800 b boo 400 Too b! $90 800 *0 400 b! 300 64 400 12 4i 40 44 '00 w x 4■ 40 x 42 as s 50 0 34 40 33 30 Y~l 8£ 30fq� q t 27 d 20 Y4 10 0 a �a s 4 3 R IMMM OF IMALIL IpiO4 ,MN. 1415 W"EKGEO OUTLET CULVERT FIJWIgfi FULL !x P.M erirn. MA wii..".4. —pw. Mw YF _! w11M14 Mi"$ M 1% 41144. V"14.rf LO Q�e +y° O� fp W W e° TJy = Od r. S 3 00 t 4 J •00 40q �o to HEAD FOR STANDARD C. M. PIPE CULVERTS FLOWING FULL n = 0.024 COUNTY OFROANOKE ;444x/1/16 6A-8 CULVERTS CULVERTS APPENDIX 6A OUTLET CONTROL, CIRCULAR CONCRETE PIPE RECONIWNDED MANNING'S n -VALUES Type of Conduit Wall Description Manning's n Concrete Pipe Smooth walls 0.010 - 0.013 Concrete Boxes Smooth walls 0.012 - 0.015 Corrugated Metal 2 2/3 by 'h inch 0.022 - 0.027 Pipes and Boxes, Annular or corrugations Helical Pipe 6 by 1 inch 0.022 - 0.025 corrugations 5 by 1 inch 0.025 - 0.026 corrugations 3 by 1 inch 0.027 - 0.028 corrugations 6 by 2 inch 0.033 - 0.035 structural plate 9 by 2'h inch 0.033 - 0.037 structural plate Corrugated Metal 2 2/3 by 'h inch corrugations 0.012 - 0.024 Pipe Spiral Rib Metal Smooth walls 0.012-0.013 (Steel or Alum.) PVC Smooth interior 0.010 - 0.012 Polyethylene (PE or HDPE) Smooth interior 0.011 - 0.013 Corrugated PE or HDPE Corrugated interior 0.022 - 0.026 Note 1:The values indicated in this table are recommended Manning's "n" design values. Actual field values may vary depending on the effects of abrasion, corrosion, deflection, and joint conditions. Concrete pipe with poor joints and deteriorated walls may have "n" values of 0.014 to 0.018. Corrugated metal with join and wall problems may also have higher "n" values, and in addition, may experience shape changes which could adversely affect the general hydraulic characteristics of the culvert. Note 2:Fore further information concerning Manning n values for selected conduits consult Hydraulic Design of Highway Culverts, Federal Highway Administration, HDS No. 5, page 163. COUNTY OF ROANOKE ;444x/1/16 6A-9 CULVERTS CULVERTS APPENDIX 6A ENTRANCE LOSS COEFFICIENTS (Ke) OUTLET CONTROL, FULL OR PARTIALLY FULL Type of Structure and Design of Entrance Coefficient Pipe, Concrete Mitered to conform to fill slope 0.7 End -section conforming to fill slope 0.5 Projecting from fill, square cut end 0.5 Headwall or headwall and wingwall Square -edge 0.5 Rounded (radius = 1/12 D) 0.2 Socket end of pipe (groove end) 0.2 Projecting from fill, socket end (groove end) 0.2 Beveled edges, 33.7° or 45° bevels 0.2 Side or slope -tapered inlet 0.2 Pipe, Corrugated Metal (or Corrugated HDPE) Projecting from fill (no headwall) 0.9 Mitered to conform to fill slope, paved or unpaved slope 0.7 Headwall or headwall and wingwall, square -edge 0.5 End section conforming and to fill slope 0.5 Beveled edges, 33.7° or 45° bevels 0.2 Side or slope -tapered inlet 0.2 Box, Reinforced Concrete Wingwalls parallel (extension of sides), 0.7 square edged at crown Wingwalls at 10° to 25° or 30° to 75° to barrel, square edged on 3 edges 0.5 rounded on 3 edges to radius of 1/12 barrel 0.2 Wingwalls at 30° to 750 to barrel, crown edge rounded to radius 1/12 of barrel 0.2 Side or slope -tapered inlet 0.2 Note: End Section conforming to fill slope made of metal, concrete, or HDPE, are the sections commonly available from manufacturers. From limited hydraulic test they are equivalent in operation to a headwall in both inlet and outlet control. Some end sections incorporating a closed taper in their design have a superior hydraulic performance. These latter sections can be designed using the information given for the beveled inlet. COUNTY OF ROANOKE ;444x/1/16 6A-10 CULVERTS STORM DRAINS Chapter 7 - Storm Drains CHAPTER 7 A storm drain is a drainage system that conveys water or stormwater, consisting of two or more pipes in a series connected by one or more structures. Storm drains collect and transport stormwater from a site primarily through the use of a closed pipe network. For the storm water to be efficiently handled in a storm drain, the site must also have an efficient way to collect stormwater runoff and have it enter into the piped network. Once in the storm drain, the stormwater is routed to a discharge outfall. Storm drain systems include: Measures to get stormwater runoff to inlets, Inlets, and 4afffl Storm drain p gpipes and structures that stormwater runoff must pass through to reach the outfall This section defines criteria and restrictions that shall be used in designing and constructing public and private storm drains. See the VDOT Drainage Manual for more in-depth information. All storm drains 12 inches in diameter and larger shall have profiles prepared and submitted to the County. 7.1 References Except where more stringent requirements are presented in this Manual, storm drain collection systems shall comply with VDOT and other state requirements. The primary design reference is the VDOT Drainage Manual. Other appropriate references include: • VDOT Standards • VDOT Specifications • VA E&SC Handbook • FHWA Drainage of Highway Pavements HEC No. 12. • FHWA Urban Drainage Design Manual HEC No. 22. • VA Stormwater Management Handbook, Chapter 6 Appendix 6B (Karst Guidelines) COUNTY OF ROANOKE q444x/1/16 7-1 STORM DRAINS STORM DRAINS CHAPTER 7 7.2 Design Methodology and Criteria 7.2.1 Computation Methods Manual computations use design equations and nomographs. Results are documented on VDOT work sheets. Copies of these forms are included in Appendix 7A. • Form LD -204 Stormwater Inlet Computations • Form LD -229 Storm Drain Design Computations • Form LD -347 Hydraulic Grade Line Computations There are a number of computer programs available to design storm drainage systems. Any of these computer programs will be acceptable if their methodologies are based on the same equations and nomographs accepted by VDOT, and if they provide the same documentation of inputs, assumptions, and output as are contained on VDOT's work sheets. Computation methods are explained in detail, including comprehensive design examples, in the VDOT Drainage Manual. 7.2.2 Hydrology ,A._ _ _ Design Flow Methodology Formatted: Font: Bold Calculations establishing the design flow shall be submitted with the Stormwater Management Plan. Design flows shall be based on ultimate build -out of the contributing watershed based on the current Comprehensive Plan. 7.2.3 Design Flows The following minimum storm frequencies shall be used: A._Inlets ------------------------------------------ Formatted: Font: Bold Inlets shall be designed for storm frequencies and intensities consistent with the VDOT Drainage Manual. For reference, the VDOT table and its accompanying notes have been included in Appendix 7A. COUNTY OF ROANOKE q444x/1/16 7-2 STORM DRAINS CHAPTER 7 J._-- Storm Drains ------------------------------------- Formatted: Font: Bold Storm drains shall be designed for the storm frequencies and intensities consistent with the VDOT Drainage Manual. For reference, the VDOT table and its accompanying notes have been included in Appendix 7A. Unless otherwise specified by the VDOT Drainage Manual, a 10 -year frequency design storm shall be used in developing design flows. 7.2.4 Measures to Convey Stormwater Runoff to Inlets A._ Pavement Drainage _ _ _ _ Formatted: Font: Bold One objective in the site design is to collect and remove stormwater runoff from critical areas as efficiently as possible. A properly designed system will ensure that roadway surfaces are free of stormwater accumulations, and will protect the public from unnecessary hazards associated with water ponding and sheet flow. Except where porous pavement is used, road pavement shall be sloped transversely to drain stormwater from the roadway. A minimum cross slope of 2 percent should be applied to all roads, both primary and secondary. Greater slope should be considered where poor drainage is anticipated. Drainage structures associated with medians, curbs, and gutters should be designed to minimize accumulation of water onto travel lanes of roadways. For additional information concerning drainage of highway pavements, refer to FHWA HEC No. 12. J._ -Curb and Gutter-------------------------------- Formatted: Font: Bold Curb and gutter at the edge of pavements may be used to collect stormwater runoff from roadways. Curbing captures stormwater runoff and directs it to stormwater collection inlets while protecting adjacent properties from flooding and erosion due to sheet flow runoff from the impervious roadways. A curb and gutter forms a triangular conveyance channel. When a storm occurs, the runoff from the road creates a spread of water from the curb. The curb and gutter must be designed to convey this flow and prevent the COUNTY OF ROANOKE q444x/1/16 7-3 STORM DRAINS STORM DRAINS CHAPTER 7 spread of water from impacting traffic. The spread width of flow is determined by using VDOT nomographs or acceptable hydrological design software. For curb and gutter flow, a Manning's n value of 0.015 is used in the computational analysis. See Appendix 7A for width of maximum allowable spread. Curb and gutter dimensions and design shall meet VDOT Standards. - -C._--Open Channels------------------------------------- Formatted: Font: Bold Open channels may be used to collect site drainage and convey it to a storm drain inlet. Design requirements for open channels are covered in Chapter 5. 7.2.5 Storm Drain Inlets A. General --------------------------------------- Formatted: Font: Bold Storm drain inlets are used to collect stormwater runoff from roads, walks, or low elevations during storm events and provide a method for passing the stormwater into the storm drain system. This is usually accomplished by placing storm drain inlets at regular intervals, low points, or at key locations to intercept flows and control the stormwater spread width. The design criteria for limiting the spread of water on travel lanes are contained in the VDOT Drainage Manual. The current design table and its notes have been included in Appendix 7A There are several different types of storm drain inlets which can be used to meet this purpose, and the designer shall choose the proper inlet structure based upon site conditions and design conditions to maximize the drainage efficiencies. • Curb • Grate • Slotted Drain/Trench • Combination Drainage and Stormwater management plans shall include a contour plan with sufficient contours shown to indicate proper drainage. B. `Curb Inlets - I Formatted: Font: Bold COUNTY OF ROANOKE AW XI1/16 7-4 STORM DRAINS STORM DRAINS CHAPTER 7 Curb inlets are vertical openings in the curb covered by a top slab. These inlets can convey large quantities of water, but also allow for large amounts of debris to enter the storm drain system. Curb inlets shall be used to the maximum extent possible for pavement drainage. C. jGrate_Inlets _ _- Formatted: Font: Bold Grate inlets are horizontal grates usually used in depressed medians or other low elevations. Grate inlets are often referred to as drop inlets or DIs. Grate inlets shall be avoided in paved areas. Where they are used in pavement, inlet grates shall be bicycle safe. D. Combination Inlets ------------ I Formatted: Font: Bold Combination inlets combine both the vertical opening used by curb inlets and the horizontal grate used in grate inlets. These inlets are often used when the inlet chamber is required to be under the gutter or street pavement away from the sidewalk or other utilities. Combination inlets shall be avoided where possible. Where they are used, they FMst shall have bicycle safe grates. E. Slotted Drain Inlets _ _- Formatted: Font: Bold Slotted drain inlets are a narrow slotted opening which can collect flow at a median barrier or curb. These inlets are usually located in areas of limited space and can be used to intercept sheet flow, or collect gutter flow to help reduce ponding depth or spreading at grate inlets. F. jnlet Locations - - I Formatted: Font: Bold Inlets shall be located to meet the design requirements of the VDOT Drainage Manual for maximum spread width. In addition, inlets shall be provided, regardless of contributing drainage area as follows: • Sag points in the gutter grade; • Upstream of median breaks, crosswalks, and street intersections; • Immediately upstream and downstream of bridges; COUNTY OF ROANOKE q444x/1/16 7-5 STORM DRAINS STORM DRAINS CHAPTER 7 • On side streets at intersections, where flow is approaching the main line; • Behind curbs, shoulders, or sidewalks to drain low areas or intercept concentrated flow; and • Any low elevation in the grade. Inlets shall be avoided in pathways likely to be used by pedestrians or bicyclists. FG. Access --------------------------------------- Formatted: Font: Bold All inlets shall have a removable grate or manhole cover to allow access for clean out. All structures greater than 3 feet in depth shall be a minimum of 4° feet in diameter for maintenance access. CH` Inlet Capacities Formatted: Font: Bold The capacities of each inlet type are contained in the VDOT Drainage Manual. Documentation of inlet capacity shall be made on VDOT Form LD -204, Stormwater Inlet Computations or equivalent. SIL__ Separation of Pipes in Inlets---------------------------- Formatted: Font: Bold Where two or more pipes enter a concrete structure at or near the same elevation, a 6" minimum horizontal clearance must be maintained between the pipes. Additional clearance between pipes shall be provided if required to protect the structural integrity of the structure. IJ. Karst Terrain - I Formatted: Font: Bold Water tight joints are required where storm drainage pipe are located in karst terrain. Additionally, an A -lock premium gasket or boot is required for the pipe connection to the storm drainage structure to prevent water loss at the structure connection. 7.2.6 Storm Drain Pipes ,A.___ Flow Capacity----------------------------------- - Formatted: Font: Bold COUNTY OF ROANOKE q444x/1/16 7-6 STORM DRAINS STORM DRAINS CHAPTER 7 Based on the size and slope of the storm drain, the design capacity for a pipe flowing full can be determined using Manning's equation. Q=Ax1.49/nxW"xS"2 Where: Q = Flow in the pipe (cfs) A = Area of the pipe (ft) R = Hydraulic radius, for circular pipe R=Diameter/4 (ft) S = Storm drain slope (ft/ft) n = Pipe roughness coefficient The design flow capacity of a storm drain shall comply with the design frequencies set forth in VDOT Drainage Manual as shown in the table in Appendix 7A. In a roadway underpass, or depressed section, where ponded water can only be removed through the storm drain system, a 100 - year frequency storm event shall be used to design the storm drain at the sag point. Storm drain flow capacities shall be documented on VDOT Form LD -229, Storm Drain Design Computations or equivalent form. J1 Storm Drain Slope ..... Formatted: Font: Bold To deter the settling of debris and sediment in the storm drain pipe, the pipe shall be designed to ensure positive slope and maintain a minimum velocity of 3 feet per second during a 2 -year frequency storm or a minimum of 0.5% slope, whichever is more restrictive. A minimum drop across the structure of 0.1' shall be provided in all storm drainage structures. The maximum pipe velocity, based on the 10 -year peak flow rate, -in any storm drain shall be in accordance with VDOT requirements based on the storm drain material, but in no event shall it be greater than 20 fps. Storm drains shall be sloped to meet the velocity requirement set in this chapter. Slopes greater than 16 percent shall be avoided if possible. If unavoidable, drop structures shall be utilized in steeper terrain. In addition, storm drains with slopes steeper than 16% must have anchor blocks for support. C. Pipe Size --------------------------------------- Formatted: Font: Bold COUNTY OF ROANOKE q444x/1/16 7-7 STORM DRAINS STORM DRAINS CHAPTER 7 All storm drains located in public easements or rights-of-way shall be a minimum of 15 -inch diameter. Pipe size shall not be reduced along the direction of the flow, except as required for proper operation of stormwater management facilities. p.- --Access - ----------------------------------------- Formatted: Font: Bold Regardless of pipe size, a cleanout access point, either an inlet, manhole, or junction box shall be provided at a maximum of every 300 feet of pipe. Cleanouts can be used for pipes 6" and smaller. All pipes over 6" require an inlet or manhole. JE. ---Joints ----------------------------------------- Formatted: Font: Bold At a minimum, all joints shall be "soil tight". The County strongly recommends the use of "water -tight" joints under pavements and areas that are stormwater "hotspots". "Water -tight" joints are required for karst terrain. See Section IV and corresnondine ADS detail in ADDendix 7B for additional info in water tight joints 7.2.7 Determination of Hydraulic Grade Line A. General --------------------------------------- Formatted: Font: Bold The hydraulic grade line represents the free water surface elevation of water in a pipe system. Where the hydraulic grade line is above the top of a pipe, the pipe is flowing under pressure. The hydraulic grade line in a manhole or other structure is the elevation to which water will rise. Hydraulic grade lines shall be calculated and evaluated for all storm drains. The hydraulic grade line shall be calculated using VDOT methods and equations that are fully described in the VDOT Drainage Manual. Calculations shall be documented on VDOT Form LD -347, Hydraulic Grade Line Computations, or equivalent. A copy of this form is included in Appendix 7A. Hydraulic grade lines can also be calculated with design software (ie Storm sewer, etc.) The hydraulic grade line shall not exceed any critical elevation during the design storm. Critical elevations include rising above the ground COUNTY OF ROANOKE q444x/1/16 7-8 STORM DRAINS STORM DRAINS CHAPTER 7 elevation at inlets or other structures, or reaching an elevation where storm flow could back-up to cause flooding damage. The calculation of the hydraulic grade line begins at the system outfall and proceeds upstream to each structure on the system. The calculation is based on the principal of conservation of energy as shown below and includes major and minor energy losses: HGL„s= HGLd, + Hf+ Hm Where: HGL, _ _ Elevation of hydraulic grade line at the upstream structure Hm = Summation of minor head losses (junctions, bends, etc.) Hf =_ Pipe friction loss HGLds Elevation of hydraulic grade line at the downstream structure Major head losses are attributable to friction losses within the pipe. Minor head losses include losses from: • Junctions • Exits • Entrances • Bends in Pipes • Access holes • Conflict pipes • Plunging flow • Expansions and contractions • Appurtenances such as weirs, diverters, valves and meters B. Outfall Conditions Formatted: Font: Bold The hydraulic grade line starts at the system outfall. At this point the hydraulic grade line shall be the actual tailwater elevation or the elevation of 0.8 times the diameter of the outlet pipe, whichever is higher. If the system discharges into a detention or retention pond, the hydraulic grade shall start at the 10 year water surface elevation. C. JPipe Friction Losses Formatted: Font: Bold The friction slope is the energy slope for that run of pipe. The friction slope is determined by inserting pipe information and design flow into COUNTY OF ROANOKE q444x/1/16 7-9 STORM DRAINS STORM DRAINS CHAPTER 7 Manning's equation and solving for S (slope). The total friction headloss in the run of pipe is the friction slope multiplied by the length of the run. Where the hydraulic grade line falls below the crown of the pipe, the elevation of normal flow is the hydraulic grade line. Formatted: Fait: Bold D. Junction Losses J. General - I Formatted: Underline Junction head losses are the summation of entrance (Hi), exit (Ho), and bend losses (Ho). When calculating junction losses it is important to use actual flow velocities. If pipes are flowing partially full, then partially full velocities are used. 2. Entrance (expansion) Losses - I Formatted: Underline Entrance loss at a junction is given by: H;=K;(V,2/2g) Where: Hi= Entrance head loss Ki = Entrance loss coefficient. Ki = 0.35 Vi = Velocity in the inlet pipe. Where more than one inlet pipe - - Formatted: indent: Left: 2" is present, use the velocity from the pipe that has the greatest momentum (Q*V) g =— Gravitational acceleration constant, 32.2 ft/s2 - - Formatted: indent: First line: 0.5" 3. Exit (contraction) Losses - I Formatted: Underline Exit loss at a junction is given by: Ho=Ko(V02/2g) Where: Ho= —Exit head loss Ko Exit loss coefficient. Ko = 0.25, except that Ko = 0.3 when - - Formatted: indent: Left: 2" computing the loss leaving the initial inlet Vo = Velocity in the outlet pipe. - - Formatted: Indent: First line: 0.25' g = Gravitational acceleration constant, 32.2 ft/s2 COUNTY OF ROANOKE q444x/1/16 7-10 STORM DRAINS STORM DRAINS CHAPTER 7 4. JBend Losses - I Formatted: Underline Bend loss at a junction are dependent on the angle between the inlet and outlet pipes. If the inlet and outlet pipe are in line with one another no bend) the angle is 0 degrees and there is no bend loss. As the angle increases towards 90 degrees, the bend loss increases. Storm drain systems should not be designed with bend angles greater than 90 degrees. The bend loss is given by: Ho = K (V;z / 2g) Where: - - Formatted: Indent: Left: 1.75", First line: W - - Formatted: Indent: Left: 1.75", First line: W Ho = Head loss at bend K = Bend loss coefficient. K is determined by consulting Figure 9-10 in the VDOT Drainage Manual. A copy is included in appendix 7A. Vi = Velocity in the inlet pipe. g = Gravitational acceleration constant, 32.2 ft/s2 5. J!Iunging Losses - I Formatted: Underline Where surface inlet inflow is 20 percent or more of the total flow - - Formatted: Indent: Left: 1.75", First line: o" through a junction, or when a lateral pipe enters a junction with its invert elevation above the crown of the outgoing pipe and the flow in the lateral pipe is 20 percent or more of the total flow through the junction, the total headloss from the structure (Hi +Ho + Ho) shall be multiplied by 1.3 (increased by 30 percent). This adjustment is cumulative with the adjustment for inlet shaping. 6. Jnlet Shaping ------ I Formatted: Underline Inlet shaping refers to how the invert is shaped to provide smooth flow - - Formatted: Indent: Left: 1.75", First line: W through the structure and is required in all manholes and inlets. When VDOT Standard IS -1, inlet shaping, is used in a structure the total headloss from the structure (Hi +Ho + Ho) shall be multiplied by 0.5 (decreased by 50 percent). This adjustment is cumulative with the adjustment for plunging losses. 7.2.8 100 -Year Conditions COUNTY OF ROANOKE q444x/1/16 7-11 STORM DRAINS STORM DRAINS CHAPTER 7 Where there is the possibility of building structures flooding, conditions during .- - - Formatted: Indent: Left: r', First line: 0" the 100 -year storm shall be analyzed to verify that all existing and proposed structures do not flood. Flow from the 100 -year storm may be carried overland as well as by the storm drain system. 7.2.9 Materials A. Structures --------------------------------------- Formatted: Font: Bold • All stormwater structures (inlets, manholes, and Junction boxes) F- - - Formatted: Indent: Left: 1.5", First line: 0", Bulleted + located in public easements or rights-of-way shall be recast or cast -in- Level: 1 +Aligned at: 0.75" +Indent at: r', Tab stops: p p 1.75", Left place concrete. All structures, frames, grates, and covers shall be in accordance with VDOT Standards and VDOT Specifications. - - Formatted: Indent: Left: 1", First Zine: 0" • All storm drain structures over four (4) feet in depth -must have steps. — - - Formatted: Indent: Left: 1.5", First line: 0", Bulleted + Level: 1 + Aligned at: 0.75" + Indent at: 1", Tab stops: 1.75", Left J1 Storm DrainPpe--------------------------------- - Formatted: Font: Bold • Storm drains in the VDOT right-of-way shall be VDOT approved materials in accordance with VDOT IIM-LD-121.15 and VDOT Standard PC -1. • Storm drains not in the VDOT right -of way shall be: o Reinforced concrete pipe (RCP). o Corrugated high-density polyethylene pipe (HDPE) with an integrally formed smooth interior is allowed for sizes 48 -inch diameter or smaller. HDPE pipe is allowed for pipe slopes less than 12% and with a velocity 12 fps or less. HDPE culvert pipe cover must be in accordance with the County of Roanoke Inspection Specifications for HDPE Pipe. A copy of this document is included in Appendix 7B. - - Formatted: List Paragraph, Indent: Left: 1.81", No bullets o Culverts 60 inches in diameter or greater may be Corrugated or numbering, Tab stops: 1.56", Left Aluminized Metal Pipe (CAMP) or corrugated aluminum with a minimum 14 gauge metal. - - Formatted: List Paragraph, Indent: Left: 1.81", No bullets o The minimum cover for all pipes is two (2) feet measured from the or numbering, Tab stops: 1.56", Left final surface. Special applications for less than two (2) feet of cover COUNTY OF ROANOKE q444x/1/16 7-12 STORM DRAINS STORMORAM CHAPTER 7 will be reviewed and approved by the County Engineer individually. The maximum cover for storm drainage pipes shall at a minimum comply with the requirements of the Virginia Department of Transportation Design Manual. .- - - Formatted: List Paragraph, No bullets or numbering 7.2.10 Structural Design All inlet structures, frames and grates; and pipes shall be designed to withstand a HS -20 loading, unless a pipe crosses a railroad, in which case the pipe shall be designed for railroad loads. The structural design shall consider the depth of cover, trench width and condition, bedding type, backfill material, and compaction. 7.3 Installation All inlets, pipes, and associated structures shall be installed in accordance with VDOT - - Formatted: Indent: First line: 0" Specifications and the manufacturer's recommendations. The characteristics of the trench, bedding, and pipe material all impact the structural strength of the pipe system. The installed pipe conditions shall comply with the design assumptions and calculations. HDPE pipe installation shall comply with the County of Roanoke Inspection Specifications for HDPE Pipe. A copy of this document is included in Appendix 7B. Storm drains shall not be installed through contaminated soils or groundwater 7.3.1 Bedding Material Bedding material and installation shall comply with the requirements of the VDOT Specifications. Use Class I backfill (crusher run and 921) to one foot over the pipe for HDPE, up to the spring line for RCP. #57 stone is not allowed as pipe bedding_ 7.3.2 Backfill Backfill shall be suitable material and shall be placed and compacted in accordance with the VDOT Specifications (PB -1 detail). Use Class I backfill (crusher run) to one foot over the pipe for HDPE, and up to the spring line for RCP. — - - Formatted: Indent: First line: 0" - - Formatted: Indent: Left: 0.5", First line: 0" a - - Formatted: Indent: Left: 1", No bullets or numbering The minimum cover for all pipes is two (2) feet measured from the final surface. Special applications for less than two (2) feet of cover will be reviewed and approved by the Co= COUNTY OF ROANOKE q444x/1/16 7-13 STORM DRAINS STORM DRAINS CHAPTER 7 Engineer individually. Additional minimum depth of cover shall be provided if recommended by the manufacturer. All pipe installed must be inspected and approved by the County's Inspector prior to any backfill being placed. The Contractor must provide 24 hour notice to County prior to installing backfill so that County staff can be present for inspections. 7.3.3 Separation of Utilities Where storm drains cross other utilities, at least 1 -foot of vertical separation shall be provided. Where 1 -foot of vertical separation cannot be provided, special provisions shall be made in the bedding and backfill to avoid settlement that could cause point loadings on the storm drain or other utility. Water lines shall not pass through a storm drain inlet or manhole. 7.4 Environmental Impacts Construction or modifications to storm drains shall comply with all applicable laws and regulations. The applicant is responsible for procuring all necessary permits. 7.5 Erosion Protection at Outfalls .- - - Formatted: Indent: Left: 1", First line: 0" Erosion protection at storm drain outlets shall be provided in accordance with the - - Formatted: Indent: Left: r', First line: 0", Tab stops: Not outlet protection standards contained in the VA E&SC Handbook and the VDOT at 0.5" Drainage Manual. 7.6 Maintenance Requirements The permittee is responsible for maintenance of storm drains until construction is - - Formatted: Indent: Left: 1", First line: 0", Tab stops: r', complete, including final clean up and site stabilization, to the satisfaction of the Left + Not at 0.5" County. A48,. R.,. e ..L1ti,... Of R R-....r,.11,1♦:...1 R18 .. ,.,1.d.. ,. ^:4.1 ,. F ,..R ..r044..1„10 R f All ..r..44.1 ,1,.,,:.41 44,.♦ 1..,...r,.,1 114 4e e ..r^ nr^^-44S 1;hA11 ^4ift,:418'^^ ^.t,,,,,^.,.11,..11,.^^ 14f38 .14,.1....... -- Formatted: Indent: Left: 1", First line: 0", Tab stops: 1", that s off Festfiets flow. Pfopei4y aw er, sha4- i(�iiC-i}li�'r.2 i1v=f�Si�t-cma'1 Left + Not at 0.5" COUNTY OF ROANOKE q444x/1/16 7-14 STORM DRAINS STORM DRAINS APPENDIX 7A AIDS FOR STORM DRAIN SYSTEM DESIGN FROM CHAPTER 9, VDOT DRAINAGE MANUAL APPENDIX 7A Table 9-1, Criteria for Inlet Design Table 9-2, Design Frequencies for Storm Drain Conduit Notes that accompany Table 9-1 and Table 9-2 Figure 9-10, Losses in Junction due to Change in Direction of Flow Lateral Appendix 913-1, LD 204 Stormwater Inlet Computations Appendix 913-2, LD 229 Storm Drain Design Computations Appendix 913-3, LD 347 Hydraulic Grade Line Computations Appendix 9C-1, Flow in Triangular Gutter Sections Appendix 9C-3, Flow Characteristic Curves (24" Gutter)- VDOT Standard Appendix 9C-23, Manning's Solution for Flow in Storm Drains Appendix 9C-24, Nomograph for Computing Required Size of Circular Drain for Full Flow Appendix 9C-25, Concrete Pipe Flow Nomograph COUNTY OF ROANOKE q444x/1/16 7A-1 STORM DRAINS STORM DRAINS APPENDIX 7A CRITERIA FOR INLET DESIGN DESIGN FREQUENCIES FOR STORM DRAIN CONDUIT Roadway Classification Design Speed Design Storm Maximum Design Roadway (mph) Spread Width P Frequency Intensity Classification With or Without Shoulder I All 1 10 (year',) (in/hour) (ft) Principal Arterial <50 10 Actual Sh. Width +3 On Grade>50 10 Actual Sh. Width Sag All 10 Actual Sh. Width +3 Locations On Grade <50 N/A° 4 h Driving Lane + Gutter Width (If Any) On Grades >50 10 Actual h Driving Lane + Gutter Width (If Any) <50 N/A° 4 /2 Driving Lane + Gutter S Sag — Width (If Any) Locations >50 50 Actual h Driving Lane + Gutter Width (If Any) Minor Arterial, Collector, Local On Grade _<50 N/A° 4 Sh. Width +3 >50 N/A° 4 Sh. Width Sag N/A^ 4 Sh. Width +3 Location All On Grade All N/A° 4 h Driving Lane + Gutter o Width (If Any) y Sag N/A^ 4 /2 Driving Lane + Gutter g Location All Width (If Any) DESIGN FREQUENCIES FOR STORM DRAIN CONDUIT Roadway Classification Design Speed (mph) Design Storm Frequency (year ) Principal Arterial With Shoulder All 25 Without Shoulder _<50 10>50 25 Minor Arterial, Collector, Local With or Without Shoulder I All 1 10 COUNTY OF ROANOKE q444x/1/16 7A-2 STORM DRAINS STORM DRAINS APPENDIX 7A NOTES - CRITERIA FOR INLET DESIGN AND DESIGN FREQUENCIES FOR STORM DRAIN CONDUIT Notes I through 3 are General Notes and should be applied to any functional classification roadway where the site conditions are comparable to the conditions described in each note. ' At locations where the vertical alignment of the roadway creates a sag condition in either a depressed roadway section or a roadway section utilizing concrete barriers, and ponded water on the roadway can only be removed through the storm drain system, a 50 -year storm frequency and the actual time of concentration should be used as the design criteria for both the drop inlet and the pipe system. 2 Federal Flood Insurance criteria dictate that the effects of the 100 -year storm event (using the actual time of concentration) on buildings insured under the Flood Insurance Program must be investigated. Such cases should only be encountered where the roadway traverses a designated floodplain area containing insured buildings and the depth of water on the pavement is sufficient to overtop the curb and flow to the buildings. 3 The maximum design spread width may not be obtainable due to the pavement/shoulder slope and the height of the curb. In locations where the curb would be overtopped and water would escape the roadway section prior to achieving the maximum design spread with, the maximum depth of ponded water allowed adjacent to the curb for the design storm shall be curb height minus one (1) inch. Notes 4 through 5 should normally be applied to the specific locations as noted in the criteria table. 4 At location where it may be reasonably anticipated that the runoff from storm events with rainfall intensities greater than 4 inches per hour will overtax the drop inlet system to the point that excess flow will escape the roadway section and result in potential damage to the adjacent property and/or roadway right of way, the drop inlet system shall be analyzed for a check storm event with a rainfall intensity of 6.5 inches per hour. If all of the runoff from the check storm event is found to be contained within the roadway section, both at the site and down grade, or if runoff escaping the roadway section is found to not be damaging to adjacent property, the drop inlet system may be used as originally designed under the general criteria. If the drop inlet system fails to meet the check storm criteria, it must be re -designed to accommodate the runoff from the check storm event. 5 Drop inlets in these locations are prone to clogging and are often located in areas where maintenance is difficult. To compensate for partial clogging, the computed slot length value should be adjusted by multiplying by a factor of two (2). The adjusted computed slot length value should then be used to determine the slot length specified on the plans. COUNTY OF ROANOKE q444x/1/16 7A-3 STORM DRAINS STORM DRAINS APPENDIX 7A LOSSES IN JUNCTION DUE TO CHANGE IN DIRECTION OF FLOW LATERAL V,2 HL= K V, = Valadty of flow in lateral in f.p.s. Acceleration due to gravity, 92 ft(seclsec Feet of tread IQsi in Jct. due, to change in direotlo of lateral flow Factor Imm graph 80 I I l 1 7 I1 0 0 0.1 0.2 0.3 0.+4 0.5 0.6 07 Fa1.11..17 K COUNTY OFROANOKE q444x/1/16 7A-4 STORM DRAINS STORM DRAINS APPENDIX 7A STORMWATER INLET COMPUTATIONS (VDOT LD -204) COUNTY OFROANOKE 4444x/1/16 7A-5 STORM DRAINS 1111fl�lioi COUNTY OFROANOKE 4444x/1/16 7A-5 STORM DRAINS STORM DRAINS APPENDIX 7A STORM DRAIN DESIGN COMPUTATIONS (VDOT LD -229) N N COUNTY OFROANOKE 4444x/1/16 7A-6 STORM DRAINS STORM DRAINS APPENDIX 7A HYDRAULIC GRADE LINE COMPUTATIONS (VDOT LD -347) E W 17 N i G y a � S N 2' 4 yIN Z 7 � � N `J r CT v IS ff v It O N F m �3 � C O C d I I N � b (9 N N 23 O O a h II IP A Y Y Y Y I vD flo o a c a I YI 11 X Y Y Y � s r COUNTY OFROANOKE 4444x/1/16 7A-7 STORM DRAINS STORM DRAINS APPENDIX 7A FLOW IN TRIANGULAR GUTTER SECTIONS COUNTY OF ROANOKE q444x/1/16 7A-8 STORM DRAINS =.37 S 05 Tz,er - --- 5+ EXAMPLZ: GIVEN' _ fb=QQI 0:03 [1 5=a04 ; T =6 FT i?.8 0.2 FI W)' 0-6--40 fj a 2 4 rT 315 CM,0.036 FT -S 4.4 l].l 00'0 z 20 T (FT) 0.05 .G4 x 30 t]$ to x oxe14�� 000 ,1 icy cow rEXO04 - t}t38 4 4,GF 0.002 O, i I D:8 0.001 OOJ G _ T 0oat Ij F-DrV-Shape, use the nomograph with CLOCK 0.4 r x2 r = Sxr Sxz/(&T * Bx2) a.a�►a T 2} To determine discharge in gutter with v. w � � 76 torr,pasit areas aiopes, find Q$ swing T, and $,- Then„ un App. 9C•B to p find Eo. Ti total digrhNp Is x Q::Q jl-E,L and QivwG-%, S�+ COUNTY OF ROANOKE q444x/1/16 7A-8 STORM DRAINS STORM DRAINS APPENDIX 7A FLOW CHARACTERISTIC CURVES (24" GUTTER) rw,x.r4 -rd, rw FiO1J tidiAP4C EEi3TIC CT✓PVf-- srwr,r,.r rxw xax� re.�ea a rai s�xae -lwsr COUNTY OF ROANOKE :711114x/t/16 7A-9 STORM DRAINS STORM DRAINS APPENDIX 7A MANNING'S SOLUTION FOR FLOW IN STORM DRAINS 24001 0.5 0.4 2490 599 0, g 4.2 10017 Q.7 e06 c 0.1 4w o d.8 0.0$ tC}Q � 0.06 iOQ 240 to1.4 0.04 .340 200 MD ki w 0.02 00 18p 0r— 6.908 0 % flE u t ao 84 72 # Oe 0. O6 Y 0.944 4i1i 04-70W J tib W a 54 0. Q3 > 41, 00Y 30 64 yo- 4a 42 O. fl 2 40/ 20 �, U 36 „ x 3 0.001 m = 30 0-0 10 0, arae 0. 000ra 10 ; 24 2! 0.006 4 -- 0. 0004 2 1- - 8 5 cc o 1 S 1 0.402 = r W 4� 0.0002 a cc 12 x 10 a 0- 90G 1 y o'' B 7 D 2 y , y 0.00006 0.00004 9 I. a 4 10 Q$ 0-00002 Q6 4. S a 00001 A. A 0.3I S 0.0047006 [4.0 0"Q 4 COUNTY OF ROANOKE �4 4lti/1/16 7A-10 STORM DRAINS STORM DRAINS APPENDIX 7A NOMOGRAPH FOR COMPUTING REQUIRED SIZE OF CIRCULAR DRAIN FOR FULL FLOW 1604 4tt0 looEx_�:- +"irirr dr'sehcs+ga Q-,.� C. f;5. DOD frrcfiQ,�r {c+car rr. C7.pI5 500slope of 0.0060"p&,- font Find d►vmpecf- lSrrrChe3 cr;e `GO velocify of 3..5 filper- second. 380 6.y I0!lesufn crashed /rrre. a COUNTY OF ROANOKE W4/44x/1/16 7A-11 STORM DRAINS Za4 .6041 2 .Goal G 120 14@ .0002 90 .0*03 'DOCZ 100 54 as .aGGa .8006 Ir} va C9 ,h 72 W 66 .0Do* Cana 3 It ea pa x Se o .DOGS uaa6 a no 2 .ante 54 _80416 r 44A014 1 4LLJ •a Z 42 .0424 r z 31r p sa •r+43a•oaea 16 0� Z SO 33 ,4040 8410 y F.r 50 -00404. W ,D064 Q t4 27 C3 R .0949 ,0864 ( 241 Q 41 4 4] J'< ,aa6O IL A244 WIN 3 10 L61 i3 .0300 4200 e 9 % .404 4300 6 7 � � 12 - .0400 .4l OG 9 d /Y x0600 0640 10 S IG 1000 ,Qa DO 11 .14 44 13 a 6 IA IS a COUNTY OF ROANOKE W4/44x/1/16 7A-11 STORM DRAINS STORM DRAINS CONCRETE PIPE FLOW NOMOGRAPH iWO Soo 0001 saa -100 600 .000z w0 -aaa3 400 APPENDIX 7A 'L5 96 = Aw[ 9{] A 01 h -�[ SS 1 72 „ V ZL 44 60 }- F 6 SOC /f ! y �s•I AOS 304 Ica a.I 49 .00-1 LL' ` 1,5 so 130 W 144b LL. 70 ell- 3% CD 1 J i3 EL 24+x;9 3fl � 30 .. 3-000 Lai Lai 4D 40010 27 ,dz S 0" - 24 <` 8 gp acoo 50 0 2i J93 rix 81N u�- Y arvEiv: o a 2: arst L= #50; p = 27" CD ,Qt 4 ipe. Reod Y=5-$ fax arld Le450. AeCord .0 t,C s L4 ,j n. i IE >r .OS C7 4Q aE 20 — !3 '09 1 ,SO 12 APPENDIX 7A 'L5 COUNTY OF ROANOKE q444x/1/16 7A-12 STORM DRAINS -�[ SS 1 4 ti ZL zaa }- F 6 SOC .7 1 G 9 304 _� itF = 600 2 ,0 -a ` 1,5 W 144b r� L2 [u CD 1 J i3 EL 24+x;9 s 1 # � 3 i is 3-000 Lai Lai �4 40010 I` S 0" 1 5 4Q0# <` 8 gp acoo 7 iAooa a rix 81N u�- Y arvEiv: o a 2: arst L= #50; p = 27" Y5 SOLUTION -L Troes*d lr4Fn !h. lelf, rtad ia-Zl Cli and D=27,r R6Cbft S1=AQ5 "&d V • S.3 ipe. Reod Y=5-$ fax arld Le450. AeCord .0 t,C s L4 ,j n. SD 1$ COUNTY OF ROANOKE q444x/1/16 7A-12 STORM DRAINS STORM DRAINS APPENDIX 7B APPENDIX 7B INSTALLATION PROCEDURES FROM ROANOKE COUNTY Inspection Specifications Iifor HDPE PIPE COUNTY OF ROANOKE q444x/1/16 7B-1 STORM DRAINS STORM DRAINS INSPECTION SPECUICATIONS FOR. HDPE PIPE TABLE OF CONTENTS I. Overview II. Pre -Installation a. Trench Widths b. Dewatering III. Embedment a. Definitions b. Foundation c. Bedding d. Haunching e. Initial Backfill f. Final Backfill IV. Joints V. Typical Details APPENDIX 711 COUNTY OF ROANOKE q444x/1/16 7B-2 STORM DRAINS STORM DRAINS I_ OVERVIEW APPENDIX 7B The County of Roanoke, in conjunction with the Virginia Department of Transportation, is allowing HDPE pipe for storm sewers. HDPE pipe may be used for any size up to 48" in diameter. Anything above that must use previously approved pipe material. 11. PRE-INSTALII ATION A. Trench "Widths Trench widths used in installing HDPE pipe have been established in AASHTO Section 30 and ASTM D2321. Table 1 provides the recommended trench widths for most installations to provide the proper placement and compaction of backfill material in the haunches around the pipe. Trenching should be completed in the existing soils with sidewalls reasonably vertical to the trip of the pipe. When excavation depths or soil conditions require shoring or use of a trench box, the bottom of the shoring or trench box should be placed no lower than the top of the pipe. This prevents disruption of the backfill when shoring of trench box is removed. If this practice cannot be followed, considerations should be given to leaving the shoring in place. Refer to Table 1. TABLE i -SUGGESTED MINIMUM TRE14CH WIDTHS Nominal Pipe Diameter, (in) Pipe QD in Minimum Trench Width (in) 4 4.78 21 5 5.92 23 8 9.11 25 1a 11.36 28 12 14.45 31 15 17.57 34 18 21.2 38 24 27.8 48 3© 35.1 66 36 41.7 78 42 47.7 83 48 52.7 j 88 COUNTY OF ROANOKE 4444x/1/16 7B-3 STORM DRAINS STORM DRAINS B. Dewatering APPENDIX 7B HDPE pipe will float in standing water. Therefore, it is imperative that the trench be dry when installing the pipe. Sump pumps, well points, or other methods may be needed to insure a dry trench. Ill[. EMBEDMENT Embedment materials are those used for the foumdation, bedding, haunching, and initial backfill. An illustration of this can be found in Figure I page 5. A. Definitions I . Class I — Angular crushed stone or rock (No. 25 or 26 stone). 2. Class. 11— Clean, course grained materials, such as gravel, course sands, and gravel/sand mixtures. 3. Class 111— Course grained materials with fines including silty or clayey gravels or sands. Gravel or sand must comprise more than 50% of Class III materials. 4. Class N and. V materials are not recormnended for embedment materials. B. Foundation A stable foundation must be provided in order to insure proper installation. Unsuitable or unstable foundations maybe replaced with a suitable bedding material, placed in 5" lifts. COUNTY OF ROANOKE q444x/1/16 713-4 STORM DRAINS STORM DRAINS C. Bedding APPENDIX 713 4 The middle of the bedding, equal to 1/3 of the pipe outside diameter, should be loosely placed. The remaining stone for the bedding should be compacted to a minimum 90% standard proctor density. Class i stone will be acceptable material for use, except when the f6tindation is in soft, yielding, or otherwise unsuitable material.. Then, the bedding material shall be #57 stone for the specified depth, and then capped with. 4" of Class I stone. D. Haunching Haunching provides the pipe with its main support and strength. Extra care must be taken in installing the haunching. The haunching will extend from the bottom of the pipe up to the spring line. For larger diameter pipes (30"- 48"), embedment materials should be worked in by hand. Class I stone may be used and compacted in 8" maximum lifts, compacted to 90% standard proctor density. E. Initial Backfill Initial Backfill will extend from the spring line to 12" above the top of the pipe. The backfill material shall consist of Class I stone, compacted in 6" lifts, compacted to 90% standard proctor density. F. Final Backfill Final back fill should be the same material as the proposed embankment. Generally, the excavated material will be used for the final backfill. The final baelcEll is to he placed in 12" niaxinmrn lifts, compacted to a minimum 85% standard proctor compaction. COUNTY OF ROANOKE q444x/1/16 713-5 STORM DRAINS STORM DRAINS igarm Trench Cross Sector Excavated Tra;ich VV!dth � � Bacicil3l ` � Initial N Backfill SpringMa--- La -a �' _ r • a. Q. Haunting -� Bedding Foundation APPENDIX 7B 5 7Z" Rpe Lent Haunch Zone COUNTY OF ROANOKE q444x/1/16 713-6 STORM DRAINS STORM DRAINS APPENDIX 7B IV. JOINTS For watertight joints, an ASTM F-477 elastomeric rubber gasket shall be used at all joints of pipe. To install this gasket, the ends of the two pipes being connected shall be cleaned. The gasket shall be applied onto the bell with the marking facing the coupler. Apply lubricant liberally to both joints of the pipes. Align the pipe to push it together on grade. Generally, pipe should be laid from the downstream end and working upstream. 'Small diameter pies (>24") can be pushed together by hand. Larger diameter pipes may need to use a bar or equipment to push the pipe together. if that is used, a wood block should be used to prevent any damage to the bell of the pipe. Special care should be taken to ensure that no bedding material gets into the joints. Stone or any other material that gets into the joint may cause leaks_ Rubber gaskets are normally installed at the factory. However, if a pipe needs to be cut in the field, the gasket shall be stretched over the bell prior to connecting pipes together. COUNTY OF ROANOKE q444x/1/16 7B-7 STORM DRAINS STORM DRAINS TYPICAL DETAILS AND VDOT TABLES AND DETAILS APPENDIX 713 COUNTY OF ROANOKE q444x/1/16 713-8 STORM DRAINS STORM DRAINS F, !2xl',f APPENDIX 7B w COUNTY OFROANOKE q444x/1/16 713-9 STORM DRAINS STORM DRAINS APPENDIX 7B COUNTY OFROANOKE 4444x/1/16 713-10 STORM DRAINS STORM DRAINS APPENDIX 7B ° a S+ 04 _ C E M a - EPvE Qw NAM �azd°�d�okdc a �EzYq g H c p'-.Lg �fR�Vgw�¢w� MAP eCK pO a® ZZ Gv`i ,.w e Z Il� gi $ ���ig � ?�LL ya iiia ' gq1 W� ��,�00 N� G- oammo.am �3�Na �a Sri Ew a e Ea a �g c -001 maim 0 IftlRoll iY COUNTY OFROANOKE 4444x/1/16 713-11 STORM DRAINS STORM DRAINS H Q• C W w 7 �$ 3j "a vy C gs ow - Lu ig L spa ra_ qW._ uj w p V y r it _ 12 t e G oat � 5 W V $rp Ya APPENDIX 7B 3j "a C gs ow - $m Sn,x L spa qW._ w p V y r it _ 12 t e G oat � 5 I= J ux $rp Ya x c - ui w a r -Ln m 3 x p w APPENDIX 7B J W 1 > a- ::. tJ p � � z Q � i iL Q In u- E W J i m 3 J �-7 L.7 D:: C:)LJ J ¢ L 60-1 c, t > Z) x COUNTY COUNTY OFROANOKE q444x/1/16 713-12 STORM DRAINS C gs ow - $m Sn,x L spa qW._ w p V y t e G oat � 5 I= J $rp Ya J W 1 > a- ::. tJ p � � z Q � i iL Q In u- E W J i m 3 J �-7 L.7 D:: C:)LJ J ¢ L 60-1 c, t > Z) x COUNTY COUNTY OFROANOKE q444x/1/16 713-12 STORM DRAINS STORM DRAINS APPENDIX 7B COUNTY OF ROANOKE q444x/1/16 7B-13 STORM DRAINS t J t r rl d +d x� l M X^ _ E i. t7Z $ �� zNa W u; MAA 1p, � g \ZiY O I°1=UF- rN cFi Uo a HWr� H U Y I�rEA^.i lel zadf. Lr! k`I!JR o g 0 111 tfz:. [111 11EIINI ILa i ®�� 0 C3 W d J zoys v ��a m Z i'o`i UB :;P is $ 7 viii r bg 4 1i u. Le1 O x u �a 7 W uJ al' U La s i o sd v Z 1 Lel Lei lm a w ul 1, O a=mn � '$ � ye LL[ V V1I 0 to /Lys9 OICL. 0 rt g� a� j Q Z a,r� '^ U) m i Wi r ,w U3 b � ilillfjj ?xJXF�� '7y$uf pv� COUNTY OF ROANOKE q444x/1/16 7B-13 STORM DRAINS RESIDENTIAL LOT DRAINAGE CHAPTER 8 Chapter 8 - Residential Lot Drainage (RESERALED) Residential lot drainage�or residential lots that are part of a common plan of development , - Formatted: Highlight includes providing drainage and/or grading of the land to direct surface drainage away from building and toward streets, drainage conveyance structures, BMWs, or sheet flow. 8.1 References Except where more stringent requirements are presented in this Design Manual, lot drainage shall comply with state requirements. The primary design references are: • VDOT Drainage Manual • VA SWM Handbook • VA ESC Handbook • BMP Clearinghouse • State Building Code 8.2 General Lot Grading Lotrg ading plans establish therg ading relationships between adjacent properties, determine the drainage areas and sizing of stormwater conveyance systems and BMPs, and account for the build out of the developed lot. 8.3 Construction Plan Requirements Individual lot grading and drainage shall be shown on the site plans and shall include the following information: • All high or low points shall be labeled on the plans. • All impervious areas shall be shown on the site plans. Additionally, all impervious areas shall be shown on the plot plans and shall not exceed the impervious areas shown on the approved site plans. Building pads sizes shall be noted on the site plans and the plot plans. If plot plans show an increase in the impervious areas then additional stormwater BMPs and a redesigned site plan may be required. Designers are encouraged to provide an adequate building pad on the site plans in order to meet homebuilders desired pad size and prevent redesign of the plans. COUNTY OF ROANOKE 7144X/1/16 8-1 RESIDENTIAL LOT DRAINAGE RESIDENTIAL LOT DRAINAGE CHAPTER 8 • Proposed and existing contours at two foot intervals. The proposed contours on Plot plans shall conform with the intent of the approved site plan". - - Formatted: Font: Not Bold •-----�-----------------------------------= Formatted: Font: Not Bold • All stormwater conveyance structures (drainage pipes, swales, etc.) shall be shown on the plans. - - Formatted: Font: Not Bold • All BMPs and swales shall be shown on the plans. • A finished floor elevation (FFE) shall be provided for each building pad on the site plan to the nearest foot. The plot plan shall show a FFE that is; onsistent with_- - - Formatted: Highlight the intent of the approved site plan. See Section 12.2 for lots that are located in a floodplain. • Roof drains shall be shown on plot plans and shall meet the drainage areas as shown on the approved site plan. Rooftop disconnects used for stormwater quality shall be shown on the site plan. • Plot plans shall show that grading is; onsistent with the approved site plan. If plot , - Formatted: Highlight plansts not consistent with the approved site plan then additional stormwater - - Formatted: Highlight structures and a redesigned plan may be required. • residential lots that are not part of a common plan of development may require - Formatted: Highlight residentialllot _ grading at the discretion of Roanoke County due to the need of _ _ _ - - - Formatted: Highlight SWM plans, drainage issues, or other circumstances= - - - - - - - - - - - - - - - - - - - - Formatted: Highlight • Residential driveways shall meet VDOT specifications for driveways abutting public roadway and Roanoke County's Street standards for driveways abutting a private roadway for maximum driveway grades. COUNTY OF ROANOKE 7444X/1/16 8-2 RESIDENTIAL LOT DRAINAGE STORMWATER DETENTION Chapter 9 — Stormwater Detention CHAPTER 9 Stormwater detention facilities are a means of attenuating increases in peak flows caused by land development. In addition to providing flood control, stormwater detention facilities can protect downstream channels from increases in erosion ara ide a w was„ e ,.F,.,,.*Rr gida4. *re&r**. This chapter addresses general requirements for detention facilities as they relate to attenuating peak flows. mss - When a storm event occurs, stormwater runoff enters the detention facility. The outlet structure allows a portion of the stormwater runoff to discharge from the facility and the remainder of the stormwater runoff is temporarily stored. After the end of the storm, water continues to discharge from the facility until it is empty. Stormwater detention facilities include: • Detention Basin • Retention Basin • Extended Detention Basin • Enhanced Extended Detention Basin • Underground Detention A detention basin is a pond that is normally dry. When a storm event occurs, it temporarily stores stormwater runoff, discharging it at a controlled rate through a hydraulic outlet structure to a downstream conveyance system. A retention basin is a stormwater pond which includes a permanent pool, even during non - rainfall periods. The pond includes storage above the normal pool elevation which temporarily stores stormwater runoff during storm events. An extended detention basin is a pond which temporarily stores runoff for a specific time period following a storm event, discharging it at a controlled rate through a hydraulic outlet structure to a downstream conveyance system. An extended detention basin is dry during non -rainfall periods. An extended detention basin provides more protection to the downstream channel from increases in erosion than a detention basin by releasing stored runoff at a lower rate over a longer time period. A typical plan and profile for an extended detention basin are detailed in the VA MP Clearinghouse. An enhanced extended detention basin is similar to an extended detention basin, but it also incorporates a shallow marsh in its bottom to : ae ,.4dit: ona alis , 40A*m04* ,.,.:,.,. ,,:............. :r C,.,.. tff 11. An underground detention facility consists of pipes or manufactured underground chambers used to temporarily store stormwater runoff following a storm event, discharging it at a controlled rate COUNTY OF ROANOKE x/1/16 9-1 STORMWATER DETENTION STORMWATER DETENTION CHAPTER 9 through a hydraulic outlet structure to a downstream conveyance system. An underground detention facility is dry during non -rainfall periods. In addition to detention and retention basins, the design requirements specified by this chapter and the VA BMP Clearinghouse shall apply to ponds created as private property amenity features.afta�. 9.1 References Except where more stringent requirements are presented in this Manual, the design and construction of stormwater detention facilities shall comply with VDOT and DCR VA BMP Clearinghouse requirements. The primary design references are: • VA SWM Handbook • VDOT Drainage Manual • VA E&SC Handbook • VDOT Standards • VA BMP Clearinghouse 9.2 Design Methodology and Criteria 9.2.1 Hydrology See Chapter 4 for methodology used to determine design flows. 9.2.2 Design Flows and Storage Volumes To properly design stormwater detention facilities, a flow routing program shall be used with an appropriate elevation — discharge - storage relationship for the design storm events. 9.2.3 Minimum Contributing Drainage Area A stormwater retention basin, which contains a permanent pool, requires at least 10 acres of watershed drainage and/or a good source of base flow to maintain the permanent pool. A minimum drainage area of 20 acres shall be used when the basin is located in an area of high visibility to prevent unsightly drying of the permanent pool. Retention basins are best suited for regional and large drainage area projects. COUNTY OF ROANOKE x/1/16 9-2 STORMWATER DETENTION STORMWATER DETENTION 9.2.4 Detention Facility Locations CHAPTER 9 Stormwater detention facilities should not be constructed within a Federal Emergency Management Agency (FEMA) designated 100 -year floodplain. If this is unavoidable, the facility shall comply with all applicable regulations under the National Flood Insurance Program, 44 CFR Part 59._ The following factors shall be addressed when siting a stormwater detention facility: • Geotechnical conditions including soil conditions; • Groundwater levels and it's potential impacts; • Karst topography; • Existing and proposed utilities; • Aesthetics on surrounding properties; and • Environmental impacts including wetlands. Stormwater basins shall be located to minimize the aesthetic impacts to the surrounding property. Basins shall be set back from property lines a distance equal to the minimum width of the applicable required buffer yard. Locate stormwater detention facilities to avoid collecting significant amounts of drainage from offsite areas. Stormwater basins shall be set back at least fifty feet from a residential dwelling structure as measured from the wall of the structure to the top of the basin embankment. In proposed single family residential subdivisions, the stormwater management facility shall be located in a single non-developed lot. 9.2.5 Basin Grading Stormwater basins shall be graded to blend into the surrounding topography with the following conditions: • Basin side slopes shall be no greater than 3:1. • Provisions shall be made for the long-term maintenance of basin slopes and periodic access for maintenance of the outlet structure, emergency spillway, and removal of accumulated sediments. COUNTY OF ROANOKE x/1/16 9-3 STORMWATER DETENTION STORMWATER DETENTION CHAPTER 9 • The maximum allowable depth of a stormwater detention basin shall be 15 feet, as measured from the top of the embankment to the lowest point in a basin. • The bottom of the basin shall have a low flow or pilot channel to facilitate complete drainage. The pilot channel shall convey flows from a 2 year storm event and prevent standing water during dry -weather conditions. The pilot channel shall be sloped a minimum of 2% if it is a grass -lined channel and at a minimum of 1% if concrete -lined. In addition to the above requirements, the follow standards of practice should be used when designing a stormwater basin to the extent possible: • The length -to -width ratio of a stormwater basin should be a minimum of 2:1. A 3:1 ratio is desired where possible. This prevents short-circuiting of the basin's storage areas. • To minimize cut and fill, the long dimension of a stormwater basin should run parallel to the contours. 9.2.6 Embankments and Emergency Spillways Stormwater basin earthen embankments shall be designed and constructed to maintain structural integrity during the 100 -year frequency storm event. When applicable, Virginia Dam Safety regulations shall apply. The minimum top width of an embankment shall be 10 feet. Width may be greater based on the overall height. Embankment side slopes shall be no steeper than 3:1. Embankments with an emergency spillway must provide at least one foot of freeboard from the maximum 100 year storm water surface elevation to the top of the embankment. An embankment without an emergency spillway must provide at least two feet of freeboard from the maximum 100 year storm water surface elevation to the top of the embankment. A geotechnical study shall be required for all stormwater basins with constructed embankments greater than 6 feet in height as measured from the base of the embankment. Cee �h" ._ 13 Ira.. _, Epti_ew. i4s of a g,.,..,.,.," e �. The commented [AG1]: geotechnical study shall be performed by a licensed geotechnical engineer or licensed geologist and the report submitted to the County. COUNTY OF ROANOKE x/1/16 9-4 STORMWATER DETENTION STORMWATER DETENTION CHAPTER 9 9.2.7 Outlet Structures and Release Rates Stormwater Release Rates - Formatted: Font: Bold Stormwater detention facilities shall be designed with an outlet structure to control the release rate from stormwater being held in the facility. Design release rates shall meet the requirements set forth in Chapter 4, except that extended detention facilities shall be designed based on releasing the design storm runoff volume in a prescribed time as indicated in the VA MP Clearinghouse. All stormwater detention facilities shall be empty within 72 hours following the storm event. Ponds created as private property amenity features, not being used as stormwater management, shall be exempt from release rate requirements. J._ Outlet Structure Criteria - Formatted: Font: Bold Outlet structures generally include a principal spillway or outlet and an emergency overflow. An outlet structure may take the form of a drop inlet, pipe, weir, or orifice. The principal spillway or outlet is intended to release flow from the design storm events at the necessary controlled rate, without allowing flow to enter the emergency spillway or overflow. The sizing of the outlet structure shall be based on the results of the hydrologic routing calculations or model. —Pile *H the *e4gdetiey E4 el,.ggit , *'+e Outlets from stormwater detention facilities shall be designed to function without manual, electrical, or mechanical controls. Where necessary, energy dissipaters shall be placed at the outfall to provide a non-erosive velocity from the facility to a channel. See Chapter 10 for the design of outfall protection. Where a stormwater basin with an earthen embankment does not have an emergency spillway, the principal outlet or spillway shall be sized to safely pass the flow from the 100 -year frequency storm without over topping the earthen embankment. In this instance, the design of the primary outlet structure shall include a 50% clogging factor duringtie 100 -year frequency storm as a safety factor. When the primary spillway is less than 24 inches wide. it shall be considered inoperative during a 100 - ear frequency storm COUNTY OF ROANOKE x/1/16 9-5 STORMWATER DETENTION STORMWATER DETENTION CHAPTER 9 Where a stormwater basin with an earthen embankment has an emergency spillway included, two conditions must be evaluated. The routed 100 -year WSEL must provide one foot of freeboard between the 100 -yr WSEL and the top of the berm. Secondly, the spillway must be evaluated to show that the 100 -year flow passes through the spillway without overtopping the berm. Both conditions must be evaluated and met. The ability to pass the 100 -year now through the spillway is typically evaluated by routing the flow through the spillway only with all other outlets ignored or by simply evaluating the 100 -year flow through the dimensional equivalent weir using F1owMaster, similar software, or applicable weir equations. Where a stormwater basin with an earthen embankment does not have an emergency spillway included, two conditions must be evaluated. The routed 100 -year WSEL must provide two feet of freeboard between the 100 -year WSEL and the top of the berm. Secondly, the principal outlet or spillway (riser weir or culvert outlet) shall be sized to safely pass the 100 - year frequency storm without overtopping the beim. For this condition, the evaluation shall include a 50% clogging factor and is typically evaluated assuming a weir length (perimeter) or culvert (diameter) based on dimensions providing 50% of the design flow area. The principal spillway must be a minimum of 24 inches wide/diameter unless calculations show that the freeboard requirements and no overtopping conditions are met. For examples of design calculations of outlet structure orifices and weirs, see the VDOT Drainage Manual and VA MP Clearinghouse. All riser structures shall be cast -in-place or precast concrete, unless a substitute material has been approved by the County. VDOT standards for riser structures may be found in the VDOT Standards. Outlet pipes shall be reinforced concrete pipe with rubber gasket watertight joints, shall have appropriate seepage control, and shall be installed on a concrete cradle from the tie of the pipe to the riser for the entire length of the outfall pipe. Concrete cradle shall be in accordance with the requirements of the VDOT Standards. C. Adequate Channel Formatted: Font: Bold Outflows from stormwater detention facilities shall be discharged to an - - Formatted: indent: Left: 1.5', First line: o" adequate channel. For adequate channel requirements, see Chapter 5. 9.2.8WateF QualityOML__ COUNTY OF ROANOKE x/1/16 9-6 STORMWATER DETENTION STORMWATER DETENTION 9.2.9 Landscaping CHAPTER 9 Stormwater basin embankments shall be vegetated. Selection and plant installation shall be in accordance with the standards of the VA SAIN 9*R44ee4BMP Clearinghouse. Trees and shrubs shall not be planted within a stormwater detention basin, nor on a stormwater basin berm, dam, or emergency spillway. The VA MP Clearinghouse shall be utilized for guidance for landscaping in the marsh areas of enhanced extended detention basins. Native plants will be used to the maximum extent possible. 9.2.10 Underground Detention �. -- Materials-------------------------------------- Formatted: Font: Bold All materials used in underground detention facilities shall be corrosion resistant consisting of reinforced concrete, aluminized corrugated metal pipe, corrugated high density polyethylene pipe, or similar approved material. J.___ Slope------------------------------------------ Formatted: Font: Bold Underground detention facilities shall be sloped to drain at a minimum floor slope of 4--05 percent. ,C-- - - Capacity Formatted: Font: Bold Underground detention facilities shall be sized such that the 100 -year design storm may be routed through the facility with no damage to the surface property. D. Accessibility and Maintainability ...... - - - I Formatted: Font: Bold COUNTY OF ROANOKE x/1/16 9-7 STORMWATER DETENTION STORMWATER DETENTION CHAPTER 9 All underground detention facilities shall be designed to be readily accessible for periodic inspection and maintenance from the surface without the need to perform confined space entry. Providing pre-treatment to remove sediments before or at the entrance of the underground detention facility to improve water quality and/or improve maintainability should be considered during the design. 9.2.11 Trash Racks Outlet structures shall be equipped with an appropriate trash rack. The trash rack shall be in accordance with the VA MP Clearinghouse. 9.3 Environmental Impacts Environmental impacts shall be carefully considered when siting stormwater detention facilities. Siting basins in low lying areas with potentially environmentally sensitive areas requires careful consideration, coordination, approval, and permitting with local, state, and federal agencies to evaluate the suitability of constructing in these areas. Environmentally sensitive areas include, but are not limited to wetlands, shallow marshes, jurisdictional waters, natural watercourses, wildlife habitat, etc. and may be protected by state and/or federal laws. With careful planning, it may be possible to incorporate wetland mitigation into the basin design. Construction of stormwater basins or modifications to existing basins shall comply with all applicable laws and regulations. The applicant is responsible for procuring all necessary permits, such as US Army Corps of Engineers and Virginia DEQ Wetland Permits, Virginia DEQ VPDES Permits, VSMP Permits, etc., prior to beginning construction. Copies of all permits shall be provided to Roanoke County prior to a land disturbing permit being issued. See Chapter 12 for more information. Detention facilities shall be coordinated with a watershed or regional plan for managing stormwater runoff, if available. 9.4 Maintenance Requirements For the post -construction maintenance of stormwater detention facilities, see Chapter 14. COUNTY OF ROANOKE x/1/16 9-8 STORMWATER DETENTION ENERGY DISSIPATION Chapter 10 - Energy Dissipation CHAPTER 10 Outlet protection for culverts, storm drains, BMP outlets, and steep open channels is essential to preventing erosion from damaging downstream channels and drainage structures. Erosion problems at culverts or at the outlet from detention basins are a common occurrence. Determination of the flow conditions, scour potential, and channel erosion resistance shall be standard procedure for all designs. Outlet protection can be a channel lining, structure, or flow barrier designed to lower excessive flow velocities and prevent erosion and scour. Outlet protection shall be employed whenever the velocity of flow at a pipe or open channel outlet exceeds the erosive velocity of the immediate downstream reach. Energy dissipation may take the form of the following: • Erosion control stone -lined channels; • Riprap outlet basins; or • Concrete baffled outlets. 10.1 References Except where more stringent requirements are presented in this Design Manual, energy dissipators shall comply with VDOT and other state requirements. The primary design references are the VDOT Drainage Manual and the VA E&SC Handbook. Other appropriate references include: • VDOT Standards • VA SWM Handbook • FHWA Design of Riprap Revetment HEC No. 11 (Pub. No. FHWA-IP-89-016 1989/2000) • FHWA Hydraulic Design of Energy Dissipators for Culverts and Channels HEC No. 14 (Pub. No. FHWA-EPD-86-110 Sept. 1983 & FHWA-IF-00-02 2000) • U.S. Dept. of the Interior — Bureau of Reclamation: Hydraulic Design of Stilling Basins and Energy Dissipators (Engineering Monograph No. 25) COUNTY OF ROANOKE q444x/l/16 10-1 ENERGY DISSIPATION ENERGY DISSIPATION CHAPTER 10 • U.S. Dept. of the Interior — Bureau of Reclamation: Design of Small Canal Structures 10.2 Design Methodology and Criteria 10.2.1 Outlet Velocity Where the outlet velocity from culverts, storm drain outfalls, or open channels is high, and channel or pipe modifications cannot adequately reduce the velocity, energy dissipation may be necessary. See the VDOT Drainage Manual Sections 7.4.6 and 8.3.2 for methodologies to determine design outlet velocities from open channels, culverts, and storm drains. For the calculation of open channel velocity, see Chapter 5. For the calculation of exit velocity from culverts, see Chapter 6. For the calculation of exit velocity from storm drain pipes, see Chapter 7. 10.2.2 Erosion Control Stone The most common form of energy dissipation is the use of erosion control stone at the outlet. Protection is provided primarily by having sufficient length and flare to dissipate energy by expanding the flow. The outlet velocities are computed for the VDOT design discharge. mid the 25 year diseha+ge. Wh:,.he , ,.i,.e4y is .r Where a pipe discharges into a channel, the apron shall extend across the channel bottom and shall extend up the bank to a depth of one foot above the maximum tailwater depth from the design storm event. The dimensional requirements of the erosion control stone apron shall be determined using the graphical curves in the VA E&SC Handbook. Generally, the use of erosion control stone for energy dissipation is limited to a maximum velocity of 19 feet per second. Alternative means of energy dissipation shall be required where the discharge velocity is greater than 19 feet per second. Alternative means include riprap outlet basins or concrete baffled outlets. The use of alternative means of energy dissipation requires the approval of VDOT when located in a VDOT right-of-way. 10.2.3 Riprap Outlet Basins COUNTY OF ROANOKE q444x/l/16 10-2 ENERGY DISSIPATION ENERGY DISSIPATION CHAPTER 10 A riprap basin is a depressed area of riprap placed at the outlet of a high velocity culvert, storm drain outlet or open channel. The riprap reduces the exit velocity by expanding the flow over the riprap length and width and forming a hydraulic jump. For the design of riprap basins, refer to the VDOT Drainage Manual. Dissipator geometry may also be computed using the "Energy Dissipator" module that is available in the computer program FHWA HY8, Culvert Analysis. Details of the riprap basin energy dissipator are included in Appendix 10A. 10.2.4 Baffled Outlets A baffled outlet usually consists of a concrete box structure with a vertical hanging concrete baffle and an end sill. Several variations of concrete baffled outlets have been published by VDOT and other state and local transportation and stormwater management agencies. A typical schematic of baffled outlets are shown in Appendix IOC. Baffled outlets are usually used when very high exit velocities exist at piped or channel transitions. Baffled outlets function by dissipating energy through impact of the water hitting the baffle and through the resulting turbulence. A tailwater depth is not required for adequate energy dissipation, but will help smooth the outlet flow. This type of outlet protection may be used with outlet velocities up to 50 feet per second. Baffled outlets are not included in state guidance handbooks. Hydraulic design procedures for baffled outlets may be found in the U.S. Department of Interior, Bureau of Reclamation, Design of Small Canal Structures, 1978 and are as follows: Step 1: Determine input parameters, including: H = _—Energy head to be dissipated, feet (can be approximated as the difference between --channel invert elevations at the inlet and outlet). Where: Q = Design discharge, cubic feet/second v = Theoretical discharge velocity determined from 2 g H, feet/second A = Flow area, Q / v, feetz COUNTY OF ROANOKE q444x/l/16 10-3 ENERGY DISSIPATION ENERGY DISSIPATION CHAPTER 10 d = Flow depth entering the basin, ft Fr = Froude number = v / ( g d )0 5, dimensionless g _Gravitational constant = 32.2 feet/second2 Step 2: Calculate the minimum basin width, W, in feet, using the following equation: W / d = 2.88 (Fr)"" Where: W = minimum basin width, feet d = depth of incoming flow, feet Fr = Fronde number = v / ( g d )0s The limits of the W/d ratio are from 3 to 10, which corresponds to Fronde numbers 1 to 9. If the basin is much wider than W, flow will pass under the baffle and energy dissipation will not be effective. Sten 3: Calculate other basin dimensions as a function of W. Refer to the Schematic of Baffled Outlet in Appendix LOCA for other dimensions as a function of W and to identify variables that are used below in other steps. Sten 4: Calculate the reauired Drotection for the transition from the baffled outlet to the natural channel based on the outlet width. A riprap apron shall be added of width W, length W (or a 5 -foot minimum), and depth f (W/6). The side slopes shall be 1.5:1, and the median rock diameter shall be at least W/20. Sten 5: Calculate the baffled outlet invert elevation based on the expected tailwater. The maximum distance between expected tailwater elevation and the invert should be b+f or some flow will go over the baffle with no energy dissipation. If the tailwater is known and fairly controlled, the baffled outlet invert should be a distance ( b / 2 ) + f below the calculated tailwater elevation. If tailwater is uncontrolled, the baffled outlet invert should be a distance f below the downstream channel invert. COUNTY OF ROANOKE q4/44x/1/16 10-4 ENERGY DISSIPATION ENERGY DISSIPATION CHAPTER 10 Step 6: Calculate the outlet pipe diameter entering the basin assuming a velocity_ of 12 fps flowing full. Step 7: If the entrance pipe slopes steeply downward, the entrance pipe shall be turned horizontal for at least 3 feet before entering the baffled outlet. Step 8: If it is possible that both the upstream and downstream ends of the pipe will be submerged provide an air vent approximately 1/6 of the pipe diameter near the upstream end to prevent pressure fluctuations and possible surging flow nnnditinnc 10.2.5 Energy Dissipator for Paved Areas For energy dissipation from velocities from paved channels or flumes, use VDOT Standards. Schematics of energy dissipators for paved flumes has been included in Appendix IOC. 10.2.6 Additional Energy Dissipators For additional energy dissipators, refer to FHWA HEC No 14 entitled, Hydraulic Design of Energy Dissipators for Culverts and Channels. 10.3 Installation Requirements Energy dissipators shall be installed and constructed according to all applicable FHWA, VDOT, and other state requirements and recommendations. 10.4 Easements Where an energy dissipater will be owned by a public jurisdiction or agency, a drainage easement must encompass the entire energy dissipator, and provide an additional area 10 feet wide around the entire energy dissipator to provide for maintenance. 10.5 Environmental Impacts Construction or modifications to energy dissipation structures shall comply with all applicable laws and regulations. The applicant is responsible for procuring all necessary permits, such as US Army Corps of Engineers and VA DEQ Wetland Permits, etc. 10.6 Maintenance Requirements The permittee is responsible for maintenance of energy dissipation structures until construction is complete, including final clean up and site stabilization, to the satisfaction of the County. After the completion of construction, property owners or responsible COUNTY OF ROANOKE q444x/l/16 10-5 ENERGY DISSIPATION ENERGY DISSIPATION CHAPTER 10 parties are responsible for maintenance of all energy dissipation structures located in private easements. COUNTY OF ROANOKE q444a/1/16 10-6 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10A AIDS FOR ENERGY DISSIPATION DESIGN FROM VDOT DRAINAGE MANUAL Figure 8E-1, Details of Riprap Basin Energy Dissipator Figure 8E-3, Riprap Basin Design Checklist APPENDIX 10A COUNTY OF ROANOKE q444a/1/16 1OA-1 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10A COUNTY OF ROANOKE q444a/1/16 1OA-2 ENERGY DISSIPATION ENERGY DISSIPATION Chapter 8 — Culverts APPENDIX 10A Appendix 8E-1 Energy Dissipation BISS1PArOR POOL MROR IB6,oRa ry >�+. In, +xOr£Pa OF •M'SE C I Z TOP OF .. 4 TOP OF RPRM TOP 6F NATIIFAL Jl E CHwNEL r, rw ZCNTPL PIPE CULVERT Wn= BARREL WIDTH F111 OR OR T, s+amu. ABOUT � � ]tl yo OR Sa �,yV, L5�a 1Sft. Mw. 2d� OR yaya OP. rsd,,,x. 15c,„,,. THICKENED OR SLOPING H%RlZaiuru � � TOE OPTIOI CONSTRUCT CE SECTION IF DOWNSTREAM CHANNEL DEGRADATION IS A:VTICIPA7CD. 6� A� B� flERM - FaTe B HALF PLAN BERwa ns 2tlsp OR i. S1 uN�, xp TGRN [MANNiL E Eita�AlETO Tw5 SEC. �A-A Bf KFILL WITH RIPRAP SEC. C -C 1 3tl'o � 2 I • � I,Stluu_ % .EAS R IJIPEL AS KwIRED T4 SUPPORT RIFF AP Td SOVPORT RWRrP . Yf_a OH I.SGu,u Ef ACVLQ TO 1 LINE. 80LKF6L -11 RIPRA° SEC - 13-e SEC.D-D NOTE A - IF E%IT VELOCITY OF BASIN IS SPECIFIEO,E%TEND BASIN AS REBURIED TO OBTAIN SUFFICIENT CROSS-SECTIONAL AREA AT SECTION A -A 5UCH THAT Qd ACROSs SECTION AREA AT SZCA-A] S?LC.FIEO EXIT VELOCITY. NOTE B - WARR BASIN TO CONFORM TO NATIJRAJ_ STREAM CHANNEL. TOP OF RIPRAP IN FLOOR OF BASIN SHOULD BE AT SHE SAME ELEVATION OR LOWER THAN NATURAL CHANNEL B07TOM AT SEC. A -A Figure 8E-1. Details of Riprap Basin Energy Dissipator 8E-4 .1 13 VDOT D.i-g. 114-1 COUNTY OF ROANOKE q444a/1/16 1OA-3 ENERGY DISSIPATION OF •M'SE �� �.�' z Jl E NOTE; Wo= DIAMETER FOR F` R// I APR�u PIPE CULVERT Wn= BARREL WIDTH F111 TY Zn d-RVDPT T, s+amu. ABOUT � � BOX CULVERT w<< SPAN OF PIPE -ARCH CULVERT _ H%RlZaiuru � � HALF PLAN BERwa ns 2tlsp OR i. S1 uN�, xp TGRN [MANNiL E Eita�AlETO Tw5 SEC. �A-A Bf KFILL WITH RIPRAP SEC. C -C 1 3tl'o � 2 I • � I,Stluu_ % .EAS R IJIPEL AS KwIRED T4 SUPPORT RIFF AP Td SOVPORT RWRrP . Yf_a OH I.SGu,u Ef ACVLQ TO 1 LINE. 80LKF6L -11 RIPRA° SEC - 13-e SEC.D-D NOTE A - IF E%IT VELOCITY OF BASIN IS SPECIFIEO,E%TEND BASIN AS REBURIED TO OBTAIN SUFFICIENT CROSS-SECTIONAL AREA AT SECTION A -A 5UCH THAT Qd ACROSs SECTION AREA AT SZCA-A] S?LC.FIEO EXIT VELOCITY. NOTE B - WARR BASIN TO CONFORM TO NATIJRAJ_ STREAM CHANNEL. TOP OF RIPRAP IN FLOOR OF BASIN SHOULD BE AT SHE SAME ELEVATION OR LOWER THAN NATURAL CHANNEL B07TOM AT SEC. A -A Figure 8E-1. Details of Riprap Basin Energy Dissipator 8E-4 .1 13 VDOT D.i-g. 114-1 COUNTY OF ROANOKE q444a/1/16 1OA-3 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10A -- C15$IPIT9R POOL All ~w To- Of UEAN raO Ff w TOP OF9IpRSP I! TOP O% NATURAL -- Jl �'#1ANNfL IC.'HI' ZCNTAL C[ y .7dFL ok 2a2d� e.S R OK15a Xd Ort 2tt 4R 1.Sdr.x. SEC. A -A u. rraeKEwEn OR SLOPING 10,,, OR I.]e'•.Y. • TQE �PTIRPEAL. Ov1'+5'ikuCT C SECTION ®.0.KFILL W17H RIrHAI+ 13 DcwNSTAEAM CNa IN+'eL. SEC. i TO 5%,'PPPAT RIPRAP DEGRADATION IS ANTICIPATED,. €x^.SNA-[ TO 7^.3 LINE, s,ERu A$ R;OLJF" OACKLILL MTX PJPR.'W dq SEC. B -B SEC. D -D WON T zf � 31 k'n' DIAMETER FOR 4 f Yr'"r I iwR •i PIPE MORi } wm. BARREL EL IVIE]TTI I rOR BOX CULVERT 1'r 7`1 i•uu, li SPANS OF PIP£ -ARCH I 1u: �"—'^� of CULVERT J G }TALE PLAN I � NOTE 5'-' A+i 1 I I SEC. A -A 9ERM 7d9E 10,,, OR I.]e'•.Y. • %[AV ATR 10 Trr$ ®.0.KFILL W17H RIrHAI+ eRR>w As HR�auuR+tc SEC. i TO 5%,'PPPAT RIPRAP €x^.SNA-[ TO 7^.3 LINE, s,ERu A$ R;OLJF" OACKLILL MTX PJPR.'W TG SUPPORT 11PAV 2eso OR SEC. B -B 5'-' A+i NOTE A IF Ex1T VELCll OF BASrM IS SPECIFIED, EYTEND BASIN AS REOURIE13 To 66TAIN SL)'FICENT CROSS-SECTIDNAL AR -0. AT $?,CTION A -A SUCH 7144T Cd../�IC159 SECTION AR -__A AT SEC. A -A) - SPECF00 i VELOcITr. NO -E B WARP 3ASIN TO CONFORM TC NATURAL STREAM CHA-41 L. TOE' OF Rill' IN FLOOR OF BASIN 5114 iD BEAT THE SSAhl ELEVATION OR LONER THM NATURAL. CHANNEL BOTTOM AT SEC, A -k Figure SE -1. Details of Riprap Basin Energy Dissipator COUNTY OF ROANOKE q4/44x/1/16 1OA-4 ENERGY DISSIPATION Commented [All illegible I I I I I I I 1 I I I I I I I I I I I I I I r 1 I 9ERM 10,,, OR I.]e'•.Y. • %[AV ATR 10 Trr$ ®.0.KFILL W17H RIrHAI+ SEC. i s,ERu A$ R;OLJF" TG SUPPORT 11PAV 2eso OR SEC. D -D NOTE A IF Ex1T VELCll OF BASrM IS SPECIFIED, EYTEND BASIN AS REOURIE13 To 66TAIN SL)'FICENT CROSS-SECTIDNAL AR -0. AT $?,CTION A -A SUCH 7144T Cd../�IC159 SECTION AR -__A AT SEC. A -A) - SPECF00 i VELOcITr. NO -E B WARP 3ASIN TO CONFORM TC NATURAL STREAM CHA-41 L. TOE' OF Rill' IN FLOOR OF BASIN 5114 iD BEAT THE SSAhl ELEVATION OR LONER THM NATURAL. CHANNEL BOTTOM AT SEC, A -k Figure SE -1. Details of Riprap Basin Energy Dissipator COUNTY OF ROANOKE q4/44x/1/16 1OA-4 ENERGY DISSIPATION Commented [All illegible I I I I I I I 1 I I I I I I I I I I I I I I r ENERGY DISSIPATION APPENDIX 10A Chapter 8 — Culverts Appendix 8E-1 Energy Dissipation RIPRAP BASIN TRIAL FINAL. 1 TRIAL Eq... Dcpth. ds D,(dE D� Fr.& No.. Fr Vdr h, "ID. 21 hfDp<q TAILWATER CHECK Taitwate, TW Equivalent d,pm, a, TW/dr IF T= > 0,75. nlalate riprop donnctream using Figura BEJ Dfw(4A,W" FA BASIN DIMENSIONS I F'EI71' Paul ]cngdl is the h,ger oI Imp 3W. Basin kngth is rhe larger of ISh, SW. App—ch Thickncss 3D„ Basin Thickness 2D, Figure 8E- 3. Riprap Basin Design Checklist BE -6 Of 93 VDOT Drainage Manual COUNTY OF ROANOKE q444x/l/16 1OA-5 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10A COUNTY OF ROANOKE q444a/1/16 1OA-6 ENERGY DISSIPATION ENERGY DISSIPATION I+rpjecr NQ. I7esigrict itevecu•er Tr f)CmGN VALUES (Figure 8F-2) Equi. ❑cr+:h. d, p.'de ❑a Fr M: ND. Fr lrrdr TAILWATER CHFCR Tail+ tier, TW EgU,%IIM aepA- a, Tway IF TWld, S 0.7%utYvr.ie norp dawnslfieam w0ne Frere SE -4 RIFRAP BASIN TRIAL I RNAL. I rRIA APPENDIX 10A Dare Bate 4a BAMl J DIMENSfOVS h'EIr ftxd de.Lth is dK 4i1hi dw, nrsir. Icngah a IShs me lamer uf� aw hppretsa dP�. BAMl J DIMENSfOVS h'EIr ftxd de.Lth is dK 4i1hi dw, nrsir. Icngah a IShs me lamer uf� aw hppretsa dP�. u Basin Threkn s 1 2Ci. 1 11 Figure BE. 3. Riprap Basin Design Checklist SE -6 Df id VDQ T Drainage Manual COUNTY OF ROANOKE q444a/1/16 1OA-7 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10B AIDS FOR ENERGY DISSIPATION DESIGN FROM VDOT ROAD AND BRIDGE STANDARDS Standard 114.01, Stone for Erosion Control APPENDIX 10B COUNTY OF ROANOKE x/l/16714 14 1OB-1 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10B �m w � s 0° F HHX m W I�in•ra x �$ I L'Y Jy� '( z A # gig; ~ Z 0 o �g [J j 2 d 43xe o wx.�i U $ 0 ri e = w z � m m m� a U in �s a D F U � C COUNTY OF ROANOKE %/1/167//1 4 1OB-2 ENERGY DISSIPATION 10100 Kei'/11 LW1611YLOW :\901 11]►f[IT0 APPENDIX 10C ENERGY DISSIPATION DESIGN SCHEMATICS Schematics of Baffled Outlet, from US Bureau of Reclamation, Design of Small Canal Structures (as used by the State of Georgia and State of Colorado) Standard Energy Dissipator for Use with Paved Flume, from VDOT Road and Bridge Standards Precast Energy Dissipator, from VDOT Road and Bridge Standards Level Spreader from VA DCR Stoimwater Specifications Various Energy Dissipators and Stilling Basins, from City of Knoxville, TN BMP Manual COUNTY OF ROANOKE q444x/l/16 10C-1 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX IOC VA CCR STORMWATER DESIGN SPECT FICATION NO.2 SHEET FLOW TO FILTER OR OPEN SPACE RIP RAP PLLINaE POLI RIPRAP APRON , KEY LEVEL SPREADER AYTO E)USTWn MADE CONCRETE LIP I LENGTH CF LEVEL SPFFADER I • LP TO BE 9ASED ON DESIGN FLow AND ALLOWABLE VELD TOP OF LEVEL SPREADER r SHALL 9E FLAT 1,3 IN GODRSE A.ROREOATE.' OR OTHER LNNG AS DESIGNED FOR STABILnY P{y{y VFW LIMA- SILNH tlR_tI] LIN rDW�VOCP DESIGN DISCHARGE . ria carr. nrarrrrwaa ' AAVJ 2�aa� FwFi rA �fiFT LFA3 l 3 %r11N +I 1IX MIN IN REOUWe-O STCM SZE Figure 24., Len el:Spreader. Pipe or Cliu erel F7oH^ to Filter Stri►r or Presen•ed Cheri Space Version 2.0, January 1, 2013 Page 8 o121 COUNTY OF ROANOKE q444a/1/16 10C-2 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10C SECTION Rock diameter for prof eciion= 1/20(W) Figure 4.5.41 Schematic of Baffled Outlet (Source: U.S. Npt- Df the Inlerior,10V* 4.5.22 Geargld Starmwater Managarrrynt Manual COUNTY OF ROANOKE q444a/1/16 1OC-3 Volume 2 (Technical Handbook) ENERGY DISSIPATION - - i coq L =/3 (W) SEG. A -A (w) �t 11 L PLAN -a--� Protection as re=ired I1 a= 172, 112 (WI SECTION Rock diameter for prof eciion= 1/20(W) Figure 4.5.41 Schematic of Baffled Outlet (Source: U.S. Npt- Df the Inlerior,10V* 4.5.22 Geargld Starmwater Managarrrynt Manual COUNTY OF ROANOKE q444a/1/16 1OC-3 Volume 2 (Technical Handbook) ENERGY DISSIPATION ENERGY DISSIPATION CDOT Drainage Design Manua! APPENDIX 10C Ener,T Dissipaters PLAN n, PLAN E 1 I t Ll 1p 1 t �^ a qrA ruN.s� FDOBLET qb El t V #I —t I� II M� x.20 m -S PLAN n, PLAN E 1 I t 6 —f0.29 m mAx.1 F I 1 t �^ a qrA ruN.s� FDOBLET qb I SECTION STILLING BASIN DESIGN O O S I z c b A c I ,4 n o 4n ti T 4 h,s h3 BEggIwG SECTION ALTERNATIVE END SILL Figure 11.7 USBR Type VI (Impact} Dissipater COUNTY OF ROANOKE q444a/1/16 1OC-4 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10C d N a n P W M au ao T 07 7 D W V) COUNTY OF ROANOKE q444a/1/16 1OC-5 ENERGY DISSIPATION Gl I~/� y 4 N iA I�it y Vhf N 1/� LLU z ¢1 m m m -SdSaVB !, o - -ba sada o -id Sada � N -za sada � i ¢�O -io sava J� V S �2 J� O� a S�� m ry n V u7 d N a n P W M au ao T 07 7 D W V) COUNTY OF ROANOKE q444a/1/16 1OC-5 ENERGY DISSIPATION y 4 � 0 O 00 O� sW m -SdSaVB !, -ba sada o -id Sada � N -za sada � i ¢�O -io sava J� V S �2 J� O� d N a n P W M au ao T 07 7 D W V) COUNTY OF ROANOKE q444a/1/16 1OC-5 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX 10C U 6 xx .9-1 .A- r w w> > W W a h.6 F APPENDIX 10C U 6 1-j i m e m _ F o ca Ewa jA - � M Ewa 7g c '�iYz r 4 ld Sw9l Jg APPENDIX 10C 1-j APPENDIX 10C COUNTY OF ROANOKE q444a/1/16 1OC-6 ENERGY DISSIPATION e o � Lu W F 2 W W m 4 u 6 N uj COUNTY OF ROANOKE q444a/1/16 1OC-6 ENERGY DISSIPATION ENERGY DISSIPATION APPENDIX !o COUNTY o ROANOKE SAA 1Oc7 ENERGY m»2&£o q §{ G a a Ld /[ ¥ ® / )\#§ \ G g § § « - & E § 9 / 2 { . . - - 0 m } \ - - . . , \ � m . : � COUNTY o ROANOKE SAA 1Oc7 ENERGY m»2&£o ENERGY DISSIPATION APPENDIX !o COUNTY o ROANOKE SAA mc, ENERGY m»2&£o � $! # � q � ql |`; \ ( |k� §y \` § § % k /| ; a » / k o E| N \ �| ^ / < « .� - � | E . a R � $ \ |§ i \ ||� COUNTY o ROANOKE SAA mc, ENERGY m»2&£o ENERGY DISSIPATION ACTIVITY: outlet Protection Chute blocks (size and shape vary) — Baffle piers, optional , see note I (size and shape vary) Sufficient depth for — hydraulic jump plus adequate freeboard End sill (may be dentated) Typical Stilline Basin At End of Paved Flume or Chute Computed normal flow culvert Concrete stilling basin v L flaffle5 w slow water down (see note 2) without cYcessive head loss Typical Stilling Basin Using Baffles and Elevation Drop Stagger baffle blocks laterally Typical Energy Dissipator - Baffle _Blocks _Within llcadwall APPENDIX 10C ES — 25 Securely fasten CMP Lee section with coupling bands or screws d }. .. �.. 4. n..w. J.. Support structure with sandbags or other materials to prevent movement Temporary CMP Eneru Dissipater Notes: I. This is the basic format for several types of stilling basins, USSR Type It basin does not contain baffle piers, but does have a dentated end sill. USBR Type IIl basin has baffle piers and a smooth undentated end sill. See 1IEC-14 for detailed design of concrete structures. 2. Concrete stilling basin should be approximately as wide as the downstream channel. Design baffles to retain sufficient srormwater to aet as a plunge pool for a wide range of flow values. Relies on sufflaient tailwater to halt flow velocity Typical Impact Energy Dissipater (Virginia DOT) NOT TO SCALE Figure ES -25-2 Various Energy Dissipators and Stifling Basins COUNTY OF ROANOKE q444a/1/16 10C-9 ENERGY DISSIPATION (NOT USED) Chapter 11 — (NOT USED) COUNTY OF ROANOKE '"44x/1/16 CHAPTER 11 (NOT USED) ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 Chapter 12 - Environmentally Sensitive Areas Stormwater discharges to areas with features identified as environmentally sensitive may be subject to additional requirements, or may need to utilize or restrict certain stormwater management practices. The following type of areas are considered to be "environmentally sensitive": • Floodplain —Areas identified within a 100 -year recurrence interval flood plain. • Steep Slopes — Areas with a slope of 33 percent or greater. • Stream Buffers —Setbacks and vegetative buffers established adjacent to the Roanoke River as required by the County of Roanoke zoning ordinance or designated conservation area buffer zones at each bank of streams, ponds, lakes, wetlands, and stormwater BNWs. • Critical Erosion Areas — Areas with potential serious erosion problems as defined in the VA E&SC Handbook. These fall into two sub categories. o The erosion hazard is critical if the slope length exceeds the following criteria: 0-7% slope > 300 feet 7-15% slope > 150 feet >15% slope > 75 feet o Areas may be critical if the soils are highly erodible, as classified using the United States Department of Agriculture (USDA) Natural Resources Conservation Service (formerly Soil Conservation Service) methods, either Land Capability Classification IIIe, IVe, IV, VII, or VIII or with an erodibility index factor greater than 8. • Karst Geology — Areas where the underlying geologic conditions include caves and crevices which allow stormwater to infiltrate and quickly migrate and transport potential pollutants. • Hot Spots — Areas where a high potential for stormwater pollution may occur due to current or former activity on the site. • Jurisdictional Streams and/or Water — Waters regulated by U.S. Army Corps of Engineers (USACE) under Section 404 of the Clean Water Act. A jurisdictional determination (JD) is required that identifies and separates the Corps regulated areas from non-regulated areas. Disturbance in regulated areas requires a permit form USACE. JDs are typically good for 5 years after the determination has been made by COUNTY OF ROANOKE 9/ 44X41/16 12-1 ENVIRONMENTALLY SENSITIVE AREAS OWLTAR1410041WN1►:\1 W&IBWYY\IIW.1N R X11 MyY0II'M IPJ the USACE. Third party reports by qualified professionals will be accepted for jurisdictional stream delineation. • Wetlands- Wetlands regulated by U.S. Army Corps of Engineers (USACE) under Section 404 of the Clean Water Act. A iurisdictional determination (JD) is required that identifies and delineates wetlands. Disturbance in wetlands requires a permit form USACE. JDs are typically good for 5 years after the determination has been made by the USACE. Third party reports by qualified professionals will be accepted for wetland delineation. 12.1 References The following publications may be useful in providing guidance when performing construction, establishing development limits, and developing appropriate strategies and design features to address the special concerns related to environmentally sensitive areas: • VDOT Drainage Manual • VA E&SC Handbook • VA SWM Handbook • Virginia Department of Conservation and Recreation, Technical Bulletin No. 2, Hydrologic Modeling and Design in Karst • International Building Code • The Development of the Land Capability Classification (reprinted from Readings in the History of the Soil Conservation Service), Douglas Helms, Soil Conservation Service, 1992 • Clean Water Act Section 404 • River & Harbors Act of 1899 Section 10 • FEMA Flood Map Service Center • Flood Insurance Rate Map (FIRM) COUNTY OF ROANOKE 9/ 44X41116 12-2 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 12.2 Floodplains The purpose of floodplain management is to regulate the use of the floodplains in order to protect life and property, prevent sedimentation and pollution of water resources, and to prevent or protect against the general degradation of the environment. Floodplains and their regulatory requirements are generally based on the stream flows generated by a 100 -year frequency storm and existing land development conditions. However, storms and future land development can generate flows of greater magnitude and flooding above and beyond these limits. For this reason, additional vertical and horizontal setbacks from the floodplain limits are strongly encouraged to account for future development within the upstream drainage area and to serve as a factor of safety for larger flood events. Floodplains include: • Areas identified within a 100 -year recurrence interval floodplain as identified by the Federal Emergency Management Agency (FEMA). These areas have been identified as the Floodplain Overlay District by the County of Roanoke Zoning Ordinance. • Areas identified within a 100 -year interval floodplain as identified by an applicant floodplain study. Management of floodplains in Roanoke County shall be in accordance with the requirements published in the County of Roanoke Zoning Ordinance. Under no conditions, shall the land disturbance activity adversely affect the capacity of channels, floodways, ditches, or any drainage facility or system. The lowest floor elevation of any new residential structure, as defined in the County of Roanoke Zoning Ordinance Section 30-28, shall be at least 2 feet above the base flood elevation. The lowest floor elevation of any new non-residential structure shall be at least 1 foot above the base flood elevation unless the structure is floodproofed. The elevation of the lowest floor shall be certified by a ",.,.'Registered *ufv-& e Surveyor or professional engiixeer-Engineer on an Elevation Certificate after the lowest floor is installed. Grading and cut and fill operations within the 100 -year flood plain are discouraged and must be approved by the County of Roanoke. Activity within the floodplain must also be coordinated with other regulatory requirements and agencies. These may include erosion and sediment control, stream buffer protection, FEMA, VMRC, U.S. Army Corps of Engineers, Virginia DEQ, and others. COUNTY OF ROANOKE 9/ 44X41/16 12-3 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 Construction of stormwater management impoundment structures within a floodplain shall be avoided to the extent possible. Where this is unavoidable, all stormwater management facility construction shall be in compliance with all applicable regulations under the National Flood Insurance Program, 44 CFR Part 59, and in accordance with the County of Roanoke Zoning Ordinance. The County does not have the authority to alter or modify the flood limits and/or elevations established by FEMA. Should an applicant flood study indicate any alteration in FEMA's limits and/or elevations, then the applicant must contact FEMA and obtain a map revision. 12.2.1 Applicant Flood Study Requirements A flood study, prepared by a Professional Engineer, must be prepared and submitted, by the applicant, for all areas where the drainage area is 100 acres or greater, and there are no detailed flood profiles or elevations from a FEMA Flood Insurance Study. There are two levels of studies. A detail study is required, if any development is proposed within the floodplain. Development includes grading and road crossings. A limited detail study is acceptable, if no development is proposed within the floodplain and the purpose of the study is to avoid the floodplain. A detail study involves a rigorous detailed hydrologic and hydraulic study of a flooding source reach. The typical riverine detail study includes the following minimum steps: • Field survey of stream and floodplain cross-sections • Field survey of all hydraulic structure crossings. • Collection of historical high water mark elevations and model calibration/verification, if data is available. • Detailed hydrologic & hydraulic modeling/computations • Establishment of the FEMA regulatory Floodway • Other tasks meeting all FEMA Guidelines and Specifications for Flood Hazard Mapping Partners A limited detail study may be performed when development is to occur adjacent to, but not in the existing floodplain. In most limited detail modeling, local regional regression equations along with a HEC -RAS hydraulic model will be developed. The major difference between the HEC -RAS models for the limited detail study and the detail study will be the amount of field survey information collected in the field and used to create the model and the amount of time spent on calibration to historical flood elevations. The limited detail models typically include no field survey data, and floodways are typically not computed. The COUNTY OF ROANOKE g414 x/1/16 12-4 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 methods for limited detail study are further outlined in the FEMA Guidelines and Specifications for Flood Hazard Mapping Partners In addition, the following information and items are required when an applicant flood study is submitted to Roanoke County for review: • The flood study shall be based on the ultimate land use conditions as - - Formatted: Font: Bold published in the most recent Comprehensive Plan for upstream areas. Structure locations shall be based on the ultimate build out data. • The flood study shall be prepared by a registered Professional Engineer licensed to practice engineering in Virginia, sealed, signed, and dated. • Assuming that sedimentation or scour may occur during the storm event is not acceptable. • The flood study shall compare pre- and post -development conditions to verify that the proposed development will not increase the 100 year flood elevation more than 1 foot at any point. • The flood study shall consider backwater conditions, local obstructions and, where required by the County of Roanoke Department of Community Development, the partial or complete failure of any enclosed drainage system. Consideration must be given to the overflow path, to ensure that no structures will flood in the event of system failure. • The flood study shall analyze the 100 -year flood path for all new development. • A digital version of the 100 -year flood limits and cross sections must be sepplied-pmL:ided to the County. The study and supporting data will become .public information. The site plan digital file shall be in ACAD format and tied to the correct State Plane Coordinate. • Cross sections from the study must be indicated on the site plans submitted as a part of the development review package. 12.2.2 Floodplain Delineation The limits of floodplain floodways shall be staked and flagged in the field prior to any land disturbance activities and they shall remain undisturbed during construction. After the completion of construction, the limits of floodplain COUNTY OF ROANOKE 9/ 44X41/16 12-5 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 floodways shall be checked to verify that no unauthorized filling has taken place in the floodway. The limits shall be shown on the plan and labeled with a point number and either a northing and casting or latitude and longitude points. Place floodplain limits and floodways on the final plats submitted for each property. All subdivision plats and site plans located within the floodplain in whole or in part shall include base flood elevation data. 12.3 Steep Slopes Special precautions and guidelines are required for development in areas having steep slopes, defined as thirty-three and one third percent (33.3%) or greater. These precautions and guidelines address the increased potential for soil erosion, sedimentation, water pollution and septic disposal problems associated with the development of areas with significant topographical relief. Unrestricted development of steep slopes may result in: • Rapid and/or large-scale movement of soil and rock; • Rapid and excessive stormwater run-off, • Deposition of eroded material leading to siltation of natural and man-made bodies of water; • Loss of aesthetic resource; and • Greater travel distance of septic effluent in the event of septic system failure. 12.3.1 Development Restrictions Land -disturbing activities on steep slopes are regulated by Chapter 8.1 of the County Code, "Erosion and Sediment Control and Steep Slope Development Ordinance of the County of Roanoke, Virginia." If the grade of a site is greater than 33.3%, refer to the International Building Code for steep slope development requirements. 12.3.2 Design Standards No land disturbance of steep slopes may occur without a geotechnical study that concludes that the land disturbance will result in a stable finished slope. For the requirements of a geotechnical study, see County of Roanoke Erosion and Sediment Control and Steep Slope Ordinance. COUNTY OF ROANOKE q444x/1/16- 12-6 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 Land disturbance of steep slopes require the preparation and submittal to the County of as -built plans showing that the finished geometry is in substantial conformity with the approved site plan. Site grading and measures required to control stormwater runoff shall collect and carry storm drainage away from the steep slope to the extent possible. If concentrated runoff is to be discharged in areas of steep slopes, adequate protection must be installed to prevent channel erosion and energy dissipation shall be used at the base of the steep slope to prevent erosion where the flow transitions to a shallower slope. The use of a closed conduit storm drain should be considered in accordance with Chapter 7. 12.4 Stream Buffers Stream buffers are established to provide a naturally vegetated strip of land adjacent to stream. This buffer protects the stream from encroachment by development, preserves the water, recreational, and environmental resources, protects the floodplain and floodway, retards runoff, and helps improve the water quality of stream by preventing erosion and filtering non -point source pollution from runoff. The establishment of stream buffers as a water quality measure is encouraged by the County of Roanoke. Requirements for stream buffers shall be in accordance with Section 30-75 of the County of Roanoke Zoning Ordinance- Roanoke River Conservation and Overlay District. Additionally, the development must meet the required stream setbacks as outlined in Section 30-75-5. 12.5 Critical Erosion Areas Critical erosion areas, if cleared of vegetation and exposed to the elements of nature, may experience significant erosion and sedimentation problems, including a significant loss of topsoil. These soils tend to be located on hillsides and areas with steep slopes, and adjacent to river valleys and tributaries. Critical erosion areas include 'we s4 ea'egafie : • The erosion hazard is critical if the slope length exceeds the following criteria: 0-7% slope > 300 feet COUNTY OF ROANOKE 9/ 44X41/16 12-7 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 7-15% slope > 150 feet >15% slope > 75 feet Critical erosion areas shall be indicated on the Erosion and Sediment Control Plan. To the— - - jFormatted: indent: Left: o.s", First line: o" extent feasible, disturbance of critical erosion areas shall be avoided or minimized. Where critical erosion areas are disturbed, their protection and stabilization shall specifically be addressed by the Erosion and Sediment Control Plan and the Stormwater Management Plan. 12.6 Karst Geology Developers and Designers are cautioned that construction in karst geology requires special care and study; and that they are responsible to ensure that all appropriate investigations are performed by licensed geotechnical engineers or geologists to ensure long-term soil stability for proposed buildings and site improvements. Although proper study of site conditions is the responsibility of the Developer and Designer, Roanoke County may, at its discretion, require a geotechnical investigation, prepared by a licensed geotechnical engineer or geologist, on a case by case basis. COUNTY OF ROANOKE 9/ 44X41/16 12-8 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 Karst is an underlying geology which is common in Roanoke County where the underlying rock is predominantly soluble limestone or dolomite creating caves, crevices, and other cavities in the rock. Stormwater may infiltrate to the karst geologic rock and quickly drain through the open cavities. In addition to providing a quick transport mechanism for potential stormwater pollutants, this may create quick erosion of the limestone, potentially causing sinkholes or other surface sloughing. Identification of karst geology shall be based on local geology and soils maps, aerial photography, and site visits by a person familiar with karst geology. Karst areas present problems with conventional hydrologic stormwater models, creating poor representation of runoff rates as most models do not have allowances for losses through sinkholes, crevices, or caves. A site : esti ati0r i t ,8" ,:,.j 4,.:,1,.,14:4, afeas impaeted byy.1,•..4 geology R44 A PARR h 1......1,1 044 IF -Wal ,. ,.18gy Mid fflffpS, affial P1,,.4Ogr-.1pl+y Hj ..:40 34S4.. by .. See DCR Technical Bulletin #2, Hydrologic Modeling and Design in Karst for additional information on identification, and modeling requirements for areas in karst geology. Recommended practices include: • Design the site to take maximum advantage of topography. • Minimize site disturbance, cuts, fills, and drainage alterations. • Minimize the impervious surface. • Stormwater conveyance structures shall be designed to dissipate overland flow over the largest areas possible. Avoid concentration of flows and ponding. • Stormwater management facilities located in karst areas shall be installed with a liner. T4q M- ,...*:,... A ,1:1:ties m fiat be 1,.,1..4,1,1 4 ka fs4 geology 1 :41,,.114 .. 1:4..1.1,1 A ,1:1:ties or -.14.14«..r:,... 4444U..: AFRA ., 41,..4 41„1 !`,111.14., beli,11„1s has b..«..4 geeleOnly BMP structures approved for karst areas by the VA BMP Clearinghouse will be allowed for installation. 12.7 Stormwater Hot Spots Stormwater discharges from land uses or activities with higher potential pollutant loadings, known as "hotspots", may require a greater level of stormwater treatment or the use of specific structural BMPs and pollution prevention practices. Greater COUNTY OF ROANOKE 9/ 44X41/16 12-9 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 concentrations of sediment, hydrocarbons, traces metals, pesticides, and other toxics than are found in typical stormwater runoff may qualify a site for designation as a hot spot. The following land uses and activities may be stormwater hotspots: 1. Vehicle salvage yards and recycling facilities; 4- 2. 2. Vehicle fueling stations; 2 3. Vehicle service and maintenance facilities; 4. Vehicle and equipment cleaning facilities; 4 5. Fleet storage areas (bus, truck, etc); .- - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian tent, Adjust space between Asian tent and numbers - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian tent, Adjust space between Asian tent and numbers 9. Outdoor loading and unloading facilities; L 10. Public works storage areas; 44. 11. Facilities that generate or store hazardous materials; 11 12. Commercial container nursery; 13. Golf courses; 13- 14. Chemical storage; and 44- 15. 415. Dry cleaning operations. 12.7.1 Design Restrictions COUNTY OF ROANOKE 9/ 44X41/16 12-10 ENVIRONMENTALLY SENSITIVE AREAS - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: Indent: Left: 1", No bullets or numbering Formatted: French (France) 6. Industrial sites (for SIC codes contact VA DEQ); - - Formatted: Indent: Left: 1", No bullets or numbering 7. Marinas (service and maintenance areas); - - Formatted: List Paragraph, No bullets or numbering, Adjust : space between Latin and Asian tent, Adjust space between Asian tent and numbers 8. Outdoor liquid container storage; - - Formatted: Indent: Left: 1", No bullets or numbering 9. Outdoor loading and unloading facilities; L 10. Public works storage areas; 44. 11. Facilities that generate or store hazardous materials; 11 12. Commercial container nursery; 13. Golf courses; 13- 14. Chemical storage; and 44- 15. 415. Dry cleaning operations. 12.7.1 Design Restrictions COUNTY OF ROANOKE 9/ 44X41/16 12-10 ENVIRONMENTALLY SENSITIVE AREAS - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Indent: Left: 1", No bullets or numbering - - Formatted: List Paragraph, No bullets or numbering, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Indent: Left: 1", No bullets or numbering ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 Stormwater BMP practices having an infiltration component located in stormwater hotspot areas shall be provided with adequate pretreatment or storage areas to preclude pollutants from the infiltration area. The property owner must conform with all applicable laws and regulations relevant to any chemicals or hazardous materials used on these sites. Industrial operations shall be conducted to minimize exposure of chemical storage containers to stormwater, and contain any runoff as required by law where this can not be avoided. These sites must also meet DEQ6R VSMP and DEQ VPDES permit requirements, where applicable. 12.7.2 Golf Course Development Golf courses, while maintaining impervious area and natural buffers allow for the introduction of nutrients into stormwater through fertilizers and chemicals into stormwater through the use of pesticides and herbicides. Design of golf courses, public or private, should meet the following performance standards: 1. Managed turf should be reduced by including areas of rough devoted to native plants, natural environments, and wildlife habitat enhancement; 2. An Integrated Pest Management and nutrient management plan should be prepared and followed; 3. Native or naturalized landscaping should be used to the extent possible; 4. Natural vegetation and trees along streams should be retained to the extend possible; 5. Stream crossings should be minimized; 6. Irrigation, drainage and retention systems should be designed to provide for efficient use of water and the protection of water quality; 7. Water reuse strategies should be employed when feasible; COUNTY OF ROANOKE 9/ 44X41/16 12-11 ENVIRONMENTALLY SENSITIVE AREAS ENVIRONMENTALLY SENSITIVE AREAS CHAPTER 12 Adherence to the "Environmental Principles of Golf Courses in the United States" published by the Center for Resource Management is encouraged. A Nutrient Management Plan should be developed by a certified Nutrient Management Planner consistent with DCR's Nutrient Management Training and Certification Regulations. 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1.5" Page 2: [51] Formatted Angela Gwynn 6/16/2015 4:03:00 PM Indent: Left: 0", Hanging: 1.5" Page 2: [52] Formatted Angela Gwynn 6/16/2015 4:03:00 PM Centered, Indent: Left: 0", Hanging: 1.5" GEOTECHNICAL STUDIES Chapter 13 - Geotechnical Studies (RESERVED) COUNTY OF ROANOKE '"44x/1/16 13-1 CHAPTER 13 GEOTECHNICAL STUDIES MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 Chapter 14 - Maintenance of Stormwater Management Facilities Proper maintenance of stormwater management facilities is essential to ensure proper long-term operation of these systems. Possible problems which may develop without proper maintenance include: • Stormwater structures may become clogged with debris reducing flow capacity which may cause upstream flooding; • Stormwater storage facilities may fill with sediment or debris reducing storage capacity and diminishing the ability of the facility to lower storm flows which may result in flooding downstream; • BMPs may not remove pollutants at the design levels required to meet the water quality requirements. If vegetation is not periodically cut and removed, it may release nutrients back into the environment, negating their water quality benefit. Stormwater management facilities include detention and retention basins, bioretention, grassed swales, and other BMPs that are intended to control stormwater runoff and change the characteristics of that runoff including, but not limited to, the quantity and quality, the period of release or the velocity of flow. Stormwater management facilities also include pipes and open channels, where the pipes and open channels are integral parts of the BMP (e.g. the pipes in a detention basin that convey flow from the outlet structure through an embankment to the discharge), and where the pipes and open channels are being used as BMPs to store or treat stormwater. Pipes (culverts and storm drains) and open channels that do not store or treat stormwater and are not an integral part of a BMP are storm drainage systems and not stormwater management facilities. Maintenance of stormwater management facilities are addressed in this Chapter. Maintenance of culverts, storm drains, and open channels that are not stormwater management facilities are addressed in their respective chanters. The maintenance guidance provided in this chapter is the routine maintenance that should be anticipated for typical nonproprietary BMPs; however, it is not meant to be all-inclusive. It is the applicant's responsibility to provide a project specific maintenance plan and schedule as part of the maintenance agreement. Information on BMP maintenance may also be found in the y^ 91.444 u,.raw221 v and toe Bean Clear-:n,.i.,.use website- ra f em *' Manufacturer's literature. 14.1 Responsibility for Maintenance COUNTY OF ROANOKE q 1 X11/16 14-1 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 Maintenance of stormwater management facilities is the responsibility of the permittee during construction until all work is completed, including final clean up and site stabilization, to the satisfaction of the County. At the completion of construction, maintenance of stormwater management facilities becomes the responsible party or land owner's responsibility in accordance with the executed Maintenance Agreement. The County is not responsible for maintaining private stormwater management facilities. 14.2 Maintenance Agreements A legally binding maintenance agreement specifying the parties responsible for the proper maintenance of all stormwater management facilities shall be secured prior to issuance of any permits for land disturbance activities. Responsibility for the operation and maintenance of stormwater management facilities, after the completion of construction, shall remain with the responsible party or property owner and shall legally pass to any successor or owner. The maintenance agreement shall include a project specific appendix that lists all stormwater management facilities present on the property; the minimum frequency of inspections and maintenance, and the routine maintenance that is to be performed for each stormwater management facility. The project specific appendix to the maintenance agreement is to be prepared by the applicant and submitted to the County with the Stormwater Management Plan for review. The information contained within the VA SWM Handbook-aH4. the VA BMP Clearinghouse, and Manufacturer literature shall be used, by the applicant, as a guide in preparing the project specific appendix to the maintenance agreement; however, the maintenance requirements shall be written to be specific to the project. When landscaping is a component of the stormwater management facility, a project specific maintenance schedule for the landscaping shall be provided that is reflective of the plant species that are used. The landscaping maintenance schedule shall contain guidance regarding methods, frequency, and time of year for landscape maintenance. The maintenance requirements shall stress the need to remove cut and remove vegetation from the BMP and the specific rate and method of fertilization, if any. A sample Maintenance Agreement is included on i ^ pe ff * ' ^ ^ .Roanoke County's website In addition, the applicant shall also establish easements for stormwater management facilities to grant the County the right of access for periodic inspections as described in Chapters 3 and 15. 14.3 Maintenance Program COUNTY OF ROANOKE 9 1 dx/1/16 14-2 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 A consistent maintenance program is the best way to ensure that stormwater management facilities will continue to perform their necessary functions. The following components are common to many stormwater management facilities maintenance programs and shall be followed, where applicable. • regular Inspections - Formatted: Underline Scheduled inspections and additional inspections after major storm events are necessary to understand the condition of the stormwater management facility and discover deficiencies so that they may be corrected. • Vegetation Mana eg ment _ _ _ _ _ _ _ _ _ _- Formatted: Underline Most stormwater management facilities rely on vegetation to filter sediment from stormwater and to stabilize the ground surface of the BMP. 0 blowing- - Formatted: Underline Some stormwater management facilities may have no mow zones. Do not mow areas meant to stay natural. If mowing is allowed and desired, most grasses are hardiest if maintained as an upland meadow, with a blade height of 6 to 8 inches. If a shorter lawn is desired, additional lawn care will be needed to maintain turf health. Never cut grasses below a blade height of 4 inches. Grasses on embankments should be cut at least twice in the spring growing season, once in the summer, and twice in the fall growing season. Grass clippings should be collected, removed from the BMP, and disposed of properly. Ideally grass clippings should be composted and used as fertilizer or mulch in an upland area. Grass clippings must never be dumped into streams, open channels, storm drains, ponds, or stormwater management facilities as they will release nutrients as they decay which will flow into streams. o Lertilization - Formatted: Underline One of the primary purposes of most stormwater management facilities is to remove nutrients from stormwater; therefore, it is important to not over fertilize. Often fertilization is not required, especially if grass is maintained at a height of 6 to 8 inches. Only fertilize where necessary to maintain the health of vegetation and then take care to apply only the minimum that is required. o Fest and Weed Control - Formatted: Underline Avoid unnecessary pesticide and herbicide use. When absolutely required, use pesticides and herbicides in accordance with listed instructions and never allow spray to enter water as many of these chemicals are toxic to aquatic life in small concentrations. COUNTY OF ROANOKE 9 U dx/1/16 14-3 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 ZZemoving Accumulated Sediment - - Formatted: Underline Vegetation surrounding stormwater management facilities is designed to trap sediment; therefore, vegetation is likely to become laden with sediment and bare spots may emerge. Bare spots should be raked, backfilled if needed, and covered with top soil. Disturbed areas should be reseeded and mulched. Excess material should be removed and may be used as a mulch or soil supplement. If the soil becomes compacted, then aeration may be necessary. _Unwanted Vegetation - I Formatted: Underline Embankments must be kept clear of woody plants (trees and bushes) because their roots could cause seepage or slope failure. Consistent mowing should control any unwanted vegetation. • _Slope, Embankment and Outlet Stabilization - Formatted: Underline Stable slopes and embankments are necessary to ensure that erosion does not add to water quality problems and that embankments do not breach. Maintaining a health stand of grasses on slopes and embankments and preventing the grown of deep rooted (trees and shrubs) vegetation on embankment areas are important. Animal burrows can also cause deterioration to embankments. Animal burrows should be filled in as soon as they are discovered. In some cases animal control may be needed to avoid excessive burrows. Outlet structures are particularly vulnerable to undercutting and erosion. A small problem, if it is not corrected, may quickly result in the need to replace an entire structure. Consult a professional engineer if sink holes, cracking, wet areas around the outlet pipe, pipe displacement, or rusting of the pipe is observed. • pebris and Litter Control Formatted: Underline Regular debris and litter removal will reduce the chance of clogging outlet structures, prevent damage to vegetated areas, reduce mosquito breeding habitats, improve site appearance, and reduce conditions for excessive algae growth. • Mechanical Components - Formatted: Underline Some stormwater management facilities have mechanical components including valves, sluice gates, anti -vortex devices, fence gates, locks, and access hatches that require periodic maintenance. • jnsect Control - Formatted: Underline The simplest way to control insects, particularly mosquitoes, is to avoid stagnant water. Most stormwater management facilities are designed to be dry within a short time after a rain event. If an insect problem develops in a detention basin or infiltration facility, then there is a maintenance issue that needs to be corrected. In stormwater management facilities, such as retention basins, that are designed to COUNTY OF ROANOKE 9 U dx/1/16 14-4 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 have a permanent pool of water insects may be controlled by the prompt removal of floatable debris and perhaps by introducing and maintaining a fish population. • Access Road and Area Maintenance - Formatted: Underline Most stormwater management facilities are designed to be accessible by heavy machinery for maintenance and repairs. Access should be maintained by periodic removal of woody vegetation and upkeep of gravel areas. • Sediment and Pollutant Removal - Formatted: Underline The primary purpose of many stormwater management facilities is the removal of sediments and nutrients (which are often attached to sediments). Sediment will naturally accumulate in a stormwater management facilities and must be periodically removed. The frequency of sediment removal will vary widely depending on the stormwater management facility's type and character of the contributing watershed. Removed sediments and pollutants should be properly disposed of in an upland area. They should be stabilized with vegetation so that they are not eroded by rainfall. Once sediment is removed, the stormwater management facility should be quickly restabilized, usually with vegetation. If maintenance operations disturb more than 5,000 square feet, an erosion and sediment control permit will be required before commencing work. Sediment and pollutant removal will usually take heavy equipment and is beyond the capabilities of most property owners without the assistance of appropriate contractors. • Component Repair or Replacement --------------------------------- t Formatted: Underline J Eventually, like all infrastructure, stormwater management facilities' components will need to be repaired or replaced. Components may include inflow and outflow devices, trash racks and anti -vortex devices, valves, orifices, pipes, concrete structures, filter or infiltration media, earthworks such as embankments and side slopes Following completion of construction, routine maintenance shall be performed on stormwater management facilities as required and as specified in the Maintenance Agreement. If the County becomes aware that a stormwater management facility has not been adequately maintained, is not functioning properly, or has becomes a danger to public safety, public health, or the environment, the responsible party will be notified in writing. The responsible party shall then be required to address the deficiency issue within a reasonable time as identified in the written notice. Failure to address the deficiency issue may result in enforcement actions. COUNTY OF ROANOKE 9 1 dx/1/16 14-5 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.1 Earthen Embankments Earthen embankments are an integral part of many BMPs including detention and retention basins and constructed wetlands. —For Earthen Embankments maintenance guidance, see Table 14.1. Table 14.1 Earthen Embankments Maintenance Required Action Maintenance Obiective Frequency of Action Inspections Inspect earthen embankments for signs of settlement, Annually seepage, woody vegetation growth, animal burrows, and good ground cover. Vegetation Management Objective is to maintain a healthy grass cover free of Mow grass on embankments at least trees and brush • Mow grass on embankments to a height of 6 to 8 twice during both growing seasons and inches. • Remove all trees and brush from embankment and once during the summer. at least 25' beyond embankment. When removing trees and brush, extract as much of the root as possible. • Fertilize, lime, or treat with pesticide or herbicide when needed to maintain grass health (do not over fertilize). • Reseed embankments as necessary to maintain vegetation. • Avoid over -fertilization. Slope, Embankment, • Fill animal burrows with compacted fill. . Regrade, repair, and revegetate eroded embankments. • If there are signs of seepage or embankment As needed based on and Outlet Stabilization damage observed during routine maintenance or inspections slumps consult with a professional engineer. Debris and Litter Control Keep the embankment clear of debris and litter During inspections or mowing Mechanical Com onents Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Area Maintenance Remove woody plants and maintain surface in drivable Annually condition Sediment and Pollutant Removal Not applicable Not applicable COUNTY OF ROANOKE q U XI1/16- 14-6 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 Component Repair Replace embankments that have major erosion, seepage, Infrequent and Replacement or slumping problems. Consult with a professional engineer. 14.3.2 Principal Spillways - - Formatted: Outline numbered + Level: 2 + Numbering Style: 1, 2, 3, ... + Start at: 3 + Alignment: Left + Aligned at: 0.25" + Tab after: 0.75" + Indent at: 0.75" Formatted: Indent: Left: 0.94", No bullets or numbering r Formatted: Indent: Left: 0", Hanging: 0.5", Tab stops: 0.5", List tab + Not at 0" Principal Spillways are an integral part of many BMPs including detention and retention basins Formatted: Indent: Left: 0.5", No bullets or numbering and constructed wetlands. Principal spillways normally consist of an outlet structure, pipe through an embankment, and outlet discharging to a downstream open channel. For guidance for the maintenance of Principal Spillways, see Table 14.2. Table 14.2 Principal Spillways Maintenance Required Action Maintenance Obiective Frequencv of Action Inspections Inspect outlet structure for signs of cracks, spalling, Semiannually and after broken or loose sections, or leakage, and corrosion or every major storm event damage to anti -vortex device or trash rack; inspect pipe inspect the outlet structure, pipe, and outlet protection. for signs of corrosion or settling: inspect outlet protection for signs of erosion or damage. Vegetation Management Not applicable Not applicable Slope, Embankment, Repair any erosion damage to outlet protection. As needed based on damage observed during and Outlet Stabilization routine inspections Debris and Litter Control Keep outlet structure clear of debris. Remove debris Semiannually and after from the BMP and properly dispose of in an upland area. major rain events as a minimum. Debris removal may be more frequent. Mechanical Components If a drain valve is present, exercise the valve semiannually to insure proper function. Periodically As noted lubricate the stem and paint exposed metal to protect from corrosion. Insect Control Not applicable Not applicable Access Road and Area Maintenance Remove woody plants and maintain surface in drivable Annually condition Sediment and Pollutant Removal Not applicable Not applicable Component Repair Repair or replace outlet structure components to correct Infrequently and Replacement leakage, cracks, spalling, broken or loose sections, or corrosion. Repair or replace pipe to correct settlement, leakage, or corrosion. Repair or replace outlet protection COUNTY OF ROANOKE q U XI1116 14-7 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 to correct erosion damage. Take care to avoid changing the BMP discharge characteristics and to avoid damage to the embankment. Repairs and replacements may require consulting a professional engineer. 14.3.3 Emergency Spillway Emergencv SDillways are an integral Dart of manv BMPs including detention and retention basins and constructed wetlands. Emergency spillways normally consist of an open channel, usually trapezoidal in cross-section, which are constructed beside an embankment to carry stormwater discharge from the BMP that is too great to be carried by the principal spillway. Emergency spillways should only discharge stormwater very infrequently Emergency spillways are most often vegetated (grassed), but may be protected against erosion by rip rap or concrete. For Emergency Spillways maintenance guidance, see Table 14.3. Table 14.3 Spillway Maintenance Required Action Maintenance Objective Frequency of Action Inspections Annually, and after any rain event that results in flow through the emer enc sillwa . Vegetation Management For a vegetated spillway the objective is to maintain a Mow grass at least twice during both growing seasons and healthy grass cover free of trees and brush • Mow grass to a height of 6 to 8 inches. • Remove all trees and brush from spillway. When once during the summer. removing trees and brush, extract as much of the root as possible. • Fertilize, lime, or treat with pesticide or herbicide when needed to maintain grass health (do not over fertilize). • Reseed spillway as necessary to maintain vegetation. Avoid over -fertilization. Slope, Embankment, Repair any damage to outlet. As needed based on damage observed during and Outlet Stabilization routine inspections Debris and Litter Control Keep the emergency spillway clear of debris and litter. During inspections or mowing Mechanical Components Not applicable Not applicable. Insect Control Not applicable Not applicable Access Road and Remove woody plants and maintain surface in drivable Annually COUNTY OF ROANOKE q U dx/1116- 14-8 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 Area Maintenance condition Frequency of Action Sediment and Pollutant Removal Not applicable Not applicable Component Repair Repair slopes and protective linings as needed. Infrequently and Replacement Slope, Embankment, 14.3.4 Sediment Forebav A sediment forebav is used as a pretreatment device to allow sediment to settle from the incoming stormwater runoff before it enters the balance of the BMP. A sediment forebav helps to isolate the sediment deposition in an accessible area, which facilitates BMP maintenance. For Sediment Forebav maintenance guidance, see Table 14.4. Table 14.4 Sediment Forebay Maintenance — - - Formatted: Indent: First line: 0" Required Action Maintenance Objective Frequency of Action Ins ections Observe del2th of sediment deposition Annually Vegetation Management Not applicable Not applicable Slope, Embankment, Not applicable Not applicable and Outlet Stabilization Debris and Litter Control Remove debris and litter that accumulates in the During inspections or sediment forebav as needed intermittently Mechanical Com onents Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Area Maintenance Remove woody plants and maintain surface in Annually drivable condition Sediment and Pollutant Removal Remove accumulated sediment. Dispose of Generally every 3 — 5 sediments in an upland area and stabilize with years or when 6 —12 vegetation. If necessary, obtain erosion and inches of sediment has accumulated. sediment control permit, prior to performing land disturbance. Component Repair Not applicable Not applicable and Replacement COUNTY OF ROANOKE q 1 X11116 14-9 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.5 Landscaping Landscaping is an integral part of many BMP's. It is important that the landscaping thrive in order for it to fully function for pollutant uptake and ground stabilization. For Landscaping maintenance guidance, see Table 14.5. Table 14.5 Landscaping Maintenance .- - - Formatted: Indent: First line: 0" Required Action Maintenance Objective Frequency of Action Inspections Observe landscaping growing conditions. If Monthly during the first landscaping is not thriving, correct conditions byrg owing season. Annually, in the fall, applying fertilization, pesticide, herbicide, or soil amendment. thereafter. Vegetation Management Each site shall have a site specific landscape Varies. Different plant maintenance schedule, depending on the species communities will require different levels used, that includes guidance regarding methods, frequency, and time of year for landscape of maintenance. maintenance and fertilization. Slope, Embankment, Not applicable Not applicable and Outlet Stabilization Debris and Litter Control Remove debris and litter. During inspections or as needed intermittently during vegetation management. Mechanical Components Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Area Maintenance Not applicable Not applicable Sediment and Pollutant Removal Not applicable Not applicable Component Repair Provide reinforcement planting after the first As needed based on observation during ins ections and Replacementrg owing season, if necessary. Thereafter, re lace caping that dies or fails to thrive. COUNTY OF ROANOKE q 1 X11/16 14-10 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.6 Stormwater Detention and Retention Basins For the design of basins v,._qtffifA4�-a' see GhE *e- 9. F,._ *he deli +i �. .- - - Formatted: Indent: First line: 0" fRr- 1 *,.,.M,A"A*Rr Ei alit , r*ra' Gr ,...t,.. ".see VA BMP Clearinghouse specifications. For maintenance guidance of stormwater basins, refer to the maintenance guidance for Earthen - - Formatted: Indent: First line: 0" Embankments, Principal Spillways, Emergency Spillways, Sediment Forebay, and Landscaping contained in this chapter. For additional maintenance guidance for basins, see Table 14.6. Table 14.6 Basins Maintenance (i) Required Action Maintenance Obiective Frequency of Action Ins ections Vegetation Management Slope, Embankment, and Outlet Stabilization Debris and Litter Control Keep the embankment clear of debris During inspections or mowing and litter Mechanical Com onents Insect Control Access Road and Area Maintenance Sediment and Pollutant Removal (1), also remove accumulated sediment (1), Depending on the effectiveness of the sediment from basin area. Dispose of sediments in an upland area and stabilize with forebay and the condition of the vegetation. If necessary, obtain erosion watershed, sediment removal and sediment control permit, prior to from the basin may be required performing land disturbance. every 5 — 10 years. Component Repair and Replacement (1) Refer to the maintenance guidelines for Earthen Embankments, Principal Spillways, Emergency Spillways, Sediment Forebay, and Landscaping contained in this chapter. COUNTY OF ROANOKE q 1 X11/16 14-11 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.7 Constructed Wetlands For use of constructed wetlands as a BMP, see VA BMP Clearinghouse specifications. see .- - - Formatted: indent: First line: 0" rte. For constructed wetlands maintenance guidance, refer to the maintenance guidance for Earthen Embankments, Principal Spillways, Emergency Spillways, Sediment Forebay, and Landscaping contained in this chapter. For additional maintenance guidance for constructed wetlands, see Table 14.7. - - Formatted: indent: First line: 0" Table 14.7 Constructed Wetlands(') Required Action Maintenance Obiective Frequency of Action Inspections (1), Document plant species distribution (1), Inspect at least semiannually for the first 3 - and fatality rates and verify compliance with landscaping reequirements;ey document sediment accumulations, ars" water elevations, and condition of the outlet. Ve etg ation Management Slope, Embankment, and Outlet Stabilization Debris and Litter Control Keep the embankment clear of debris During inspections or as needed and litter intermittently Mechanical Com onents Insect Control Li I U) Access Road and Area Maintenance Sediment and Pollutant Removal (1), As necessary, remove accumulated (1), Depending on the effectiveness of the sediment sediment from constructed wetland area and re-establish vegetation. Dispose of forebay and the condition of the sediments in an upland area and stabilize with vegetation. If necessary, watershed, sediment removal from the constructed wetland obtain erosion and sediment control may be required infrequently permit, prior to performing land disturbance. (every 10 years or less frequent . Component Repair and Replacement (1) Refer to the maintenance guidelines for Earthen Embankments, Principal Spillways, Emergency Spillways, Sediment Forebay, and Landscaping contained in this chapter. COUNTY OF ROANOKE q U XI1/16 14-12 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.8 Infiltration Practices For the design of infiltration basins and infiltration trenches as BMPs see VA BMP Clearinghouse specifications.Far ...,.,..i,..,ater- Ei ,.r e 94"tei: 11 of t4is r, 14.3.8.1 Infiltration Basin For Infiltration Basin maintenance guidance, refer to the maintenance guidance for Earthen .- - - Formatted: indent: First line: 0" Embankments, Principal Spillways, Emergency Spillways, Sediment Forebay, and Landscaping contained in this chapter. For additional maintenance guidance for infiltration basins, see Table 14.8A. Table 14.8A Infiltration Basin Maintenance (r) Required Action Maintenance Obiective Frequency of Action Inspections (1), Inspect basin to ensure that the basin (1), Monthly for the first 6 - functions as designed. Examine infiltration months: and thereafter semiannually and after major basin and outlet for clogging. Inspect for erosion, slumping, excessive sedimentation rain events. levels and vegetation overgrowth. Vegetation Management Slope, Embankment, and Outlet Stabilization Debris and Litter Control Keep the buffer area clean to reduce litter and During inspections or mowing floatables minimizing the clogging of the infiltration basin. Mechanical Components Ensure no standing water remains in basin Repair as needed based on after storm events. Standing water indicates observation during semiannual inspection. infiltration is clogged. Insect Control Remove accumulated sediment in basin and Remove sediment accumulation every 2 years or restore filtration area. If standing water is present during dry weather, the infiltration when infiltration basin has basin has become clogged. standing water. Access Road and Area Maintenance Sediment and Pollutant Sediment shall be removed and disposed in an Depending on the effectiveness of the sediment Removal upland area and stabilized with vegetation when sediment fills the sediment reserve forebay and the condition of capacity, or when the basin loses its infiltration capacity. If necessary, obtain the watershed, sediment removal may be required erosion and sediment control permit, prior to infrequently (every 10 years performing land disturbance. Avoid compacting the floor of the infiltration basin. or less frequent). Component Repair and Replacement (1) Refer to the maintenance guidelines for Earthen Embankments, Principal Spillways, Emergency Spillways, Sediment Forebay, and Landscaping contained in this chapter. COUNTY OF ROANOKE q U XI1116- 14-13 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.8.2 Infiltration Trench For maintenance requirements of infiltration trenches, see Table 14.813. Table 14.8B Infiltration Trench Maintenance Required Action Maintenance Objective Frequency of Action Inspections Inspect infiltration trenches to ensure that the Quarterly inspection BMP continues to function as initially for the first year, and intended. Examine for clogging of infiltration semiannual inspection trench. Document depth of water in observation well or assessable pretreatment thereafter device to assess dewater capacity of the facili . Ve etg ation Mana eg ment Buffer strips shall be mowed to 4 to 6 inches Cut grass twice during to limit unwanted vegetation. Trees shall be pruned such that the drip line both growing seasons and once during the summer. Prune overhanging trees annuall . does not extend over the surface trench. All trees shall be removed within the trench to prevent the puncture of filter fabric. Slope, Embankment, Regrade, repair, and revegetate eroded and As needed based on and Outlet Stabilization slumped buffer strips. damage observed during inspections. Debris and Litter Control Keep the buffer area clean to reduce litter and During inspections or floatables minimizing the clogging of the mowing infiltration trench. Mechanical Components Not applicable. Not applicable Insect Control Not anplicable Not agplicable Access Road and Area Maintenance Remove woody plants and maintain surface in Annually drivable condition Sediment and Pollutant Removal Remove accumulated sediment in infiltration Every 2 years or when trench and restore filtration area. sediment causes infiltration trench to have standing water. Component Repair Remove and replace top 6"-12" gravel and As needed based on and Replacement filter cloth sediment barrier. observation during inspections. COUNTY OF ROANOKE q 1 dx/1/16 14-14 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.8.3 Porous Pavement For the design of porous pavement as a BMP see VA BMP Clearinghouse specifications.- ;: 4,.4.m.,.,,.*4r a':l, e gliai3le-r- 11. For maintenance requirements of porous pavement, see Table 14.8.C. Table 14.8.0 Porous Pavement Maintenance Required Action Maintenance Objective Frequency of Action Inspections Inspect pavement to ensure proper Quarterly, and after every structural operation, and that the permeable aspect of the pavement has major rain events, until performance characteristics of not become clogged with debris. Measure water depth in storage laver the structure has been verified; thereafter, annually Ve etg ation Management Not applicable Not applicable Slope, Embankment, Not applicable Not applicable and Outlet Stabilization Debris and Litter Control Vacuum clean pavement surface, Monthly followed by high pressure water washing. Do not use sand or other abrasives during winter weather as they will clog the surface. Mechanical Com onents Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Area Maintenance Not applicable Not applicable Sediment and Pollutant Removal Not applicable Not applicable Component Repair No repair is possible. If pavement Depends on frequency and and Replacement becomes clogged, complete replacement thoroughness of pavement is required. cleaning COUNTY OF ROANOKE q 1 X11/16 14-15 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.9 Bioretention Filter See VA BMP Clearinghouse specifications Pfor the design of bioretention filters as BMPs. r Eioa . see moi. to �For maintenance guidance for bioretention filters, see Table 14.9. Table 14.9 Bioretention Filter Maintenance Required Action Maintenance Objective Frequency of Action Inspections Inspect filter to ensure that it continues Semiannually to function as initially intended. Observe sedimentation, standing water, and vegetation. Vegetation Management Provide adequate fertilization, pruning, Varies depending on plant species and other care for landscaping. Slope, Embankment, and Not applicable Not applicable Outlet Stabilization Debris and Litter Remove debris and litter. During inspections Control Mechanical Com onents Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Not applicable Not applicable Area Maintenance Sediment and Pollutant Removal Remove accumulated sediments and Annually dispose of them in an upland location and stabilize with vegetation. Component Repair Replace mulch laver. On an as needed Every 2 for routine mulch and Replacement basis replace the planting soil and ,years replacement. Every 5 years for vegetation to restore infiltration ca aci to the underdrain. plantingsoil oil replacement. COUNTY OF ROANOKE q 1 X11/16 14-16 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.10 Sand Filters See VA BMP Clearinghouse specifications for the design of sand filters. For maintenance .- - - Formatted: indent: First line: 0" guidance for sand filters, see Table 14.10. Table 14.10 Sand Filter Maintenance Required Action Maintenance Objective Frequency of Action Inspections Monitor and document water level in filter Quarterly and after each chamber and rate of dewatering after storm mai or rain event for the events. first year, semiannually and after each major rain event thereafter. Ve etg ation Management Not applicable Not applicable Slope, Embankment, Not applicable Not applicable and Outlet Stabilization Debris and Litter Control Not applicable Not applicable Mechanical Components Not applicable Note applicable Insect Control Nota licable Not licable Access Road and Area Maintenance Remove woody plants and maintain surface Annually in drivable condition Sediment and Pollutant Removal Pump out sedimentation chamber. If water Semiannually (midway has an oil skim, it should be removed by a between semiannual inspection events) firm specializing in oil recovery and recycling. Remove sediments and dispose of them properly in an appropriate landfill. Refill the first chamber with water to restore the water seal. Component Repair Remove and replace filter cloth and ballast Varies depending on the and Replacement gravel to restore filtering capacity when efficiency of the pretreatment device filter will no longer draw down within 40- hours. COUNTY OF ROANOKE q 1 X11/16 14-17 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.11 Grassed Swale See VA BMP Clearinghouse specifications for use of grassed swales as a BMP. Forrad ssed t- - - Formatted: indent: First dine: o" swale maintenance guidance, see Table 14.11. Table 14.11 Grassed Swale Maintenance Required Action Maintenance Obiective Frequency of Action Inspections Check for uniformity of vegetative cover or for • Weekly, until vegetation is established. • Thereafter, semi- annually. • In addition, inspect grassed swale for damage after mai or rain structural repair needed for concrete linings. Check for sediment and debris accumulation and for erosion problems or bank sloughing. events. Vegetation Management Objective is to maintain a healthy uniform Mow grass periodically. vegetative growth: Use proper mowing techniques. • Mow grass to a height of 6 inches. • Collect and remove grass clippings. • Periodic weeding of invasive species and Reseed as necessary. weeds. • Fertilize or treat with pesticide or herbicide when needed to maintain plant health (do not over fertilize). • Reseed and mulch any bare areas. Slope, Embankment, Regrade, repair, and revegetate eroded and As needed based on damage and Outlet Stabilization slumped areas. Repair channel lining, outlet observed. protection and rip rap where required. Debris and Litter Control Keep the channel clean to reduce litter and During inspections or moWing floatables being washed downstream. Mechanical Components Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Area Maintenance Not applicable Not applicable Sediment and Pollutant Removal Remove accumulated sediment in channels, Depends on site conditions behind check dams, and at outfalls and culverts to perform annually at a minimum. maintain flow capacity and drainage. Repair any damage that occurs during sediment removal. Component Repair Repair or replace check dams to maintain Annually or as needed and Replacement temporary ponding and to maintain filtered flow through check dams. COUNTY OF ROANOKE q U XI1116 14-18 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.12 Vegetated Filter Strip See VA BMP Clearinghouse specifications for use of vegetated filter strips as a BMP. For vegetated filter strip maintenance requirements, see Table 14.12. Table 14.12 Vegetated Filter Strip Required Action Maintenance Obiective Freguencv of Action Inspections Check the vegetation for uniformity of • Weekly, until vegetation is cover, sediment and debris accumulation, established. • Thereafter, semi-annually. and erosion. Check for proper operation of level spreader, if present. • In addition, inspect filter strip for damage after major rain events. Vegetation Management Obiective is to maintain a healthy uniform As dictated by conditions+ vegetativerg owth: • If the area is maintained as lawn use proper mowing techniques. Collect and remove grass clippings. • Periodic weeding of invasive species and weeds. • Periodic pruning of woody vegetation to stimulate grown. • Fertilize, lime, or treat with pesticide or herbicide when needed to maintain plant health (do not over fertilize). Slope, Embankment, Regrade, repair, and revegetate eroded As needed based on damage and Outlet Stabilization ground surface. observed during inspection Debris and Litter Control Keep the vegetated strip clean to reduce During inspections or mowing litter and floatables being washed downstream. Mechanical Components Not Applicable. Not Applicable. Insect Control Not Applicable. Not Applicable Access Road and Area Not Applicable. Not Applicable Maintenance Sediment and Pollutant Remove accumulated sediment and reestablish vigorous vegetation cover. Depends on site conditions Removal perform annually at a minimum. Dispose of sediments in an upland area and stabilize with vegetation. If necessary, obtain erosion and sediment control permit, prior to performing land disturbance. Component Repair and If level spreader is used, replace rigid lip Infrequently Replacement when necessary. COUNTY OF ROANOKE q U XI1116 14-19 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.13 Manufactured BMP Systems Several manufacturers have developed filter and screening devices which areag ining t- - - Formatted: indent: First gine: o" acceptability from the regulators as suitable BMPs for meeting stormwater quality requirements. These devices filter debris and sediment and other pollutants, such as metals and hydrocarbons from stormwater. Specific maintenance requirements for manufactured BMPs shall be in accordance with the - - Formatted: indent: First line: o" manufacturer's specifications and warranty requirements. rovide the Manufacturer's , - Formatted: Font: sold, underline specified guidelines for maintenance activities. See Table 14.13 for general maintenance guidance. Table 14.13 Manufactured BMP Maintenance Required Action Maintenance Objective Frequency of Action Inspections Inspect structure and inlets and outlets Semiannual or as specified by to ensure structural integrity and proper the manufacturer. functioning o1 the facility. Ve etg ation Management Not applicable Not applicable Slope, Embankment, Not applicable Not applicable and Outlet Stabilization Debris and Litter Control Remove debris and litter that interferes As needed based on impacts with proper operation. observed during semiannual ins ection. Mechanical Components Provide routine maintenance to valves, Per manufacturer's instructions. sluicegates, pumps or other mechanical devices per manufacturer's instructions. Insect Control Nota licable Not agplicable Access Road and Area Maintenance Not applicable Not applicable Sediment and Pollutant Removal Clean manufactured screen or filter Annually or as required. vault of debris, litter and floatable materials. Remove any sediment and ollutant build -M2 from the vault. Component Repair Repair or replace tank or vault structure As recommended by the manufacturer and as needed. and Replacement if leaks or cracks develop. Replace filtering media when necessary for proper functioning. COUNTY OF ROANOKE q 1 X11/16 14-20 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.14 Conservation Areas Conservation areas are naturally vegetated areas used to provide a measure of stormwater quality Formatted: Indent: First line: o" control as open space or forested areas. Conservation Areas should be maintained in their natural condition or can be planted to meet the VA BMP Clearinghouse specifications. Conservation areas reauire an easement. For Conservation Areas maintenance guidance, see Table 14.14. Table 14.14 Conservation Areas Maintenance Required Action Maintenance Obiective Frequencv of Action Inspections Check the vegetation for uniformity of cover . Quarterly, until vegetation and growth, sediment and debris accumulation, and erosion. is established. • Thereafter, annually. • In addition, inspect area for damage after maior storm events. Vegetation Management 1 Weed control to promote survival and If establishing new vegetation, rapid growth of trees and shrubs. continuous over first two years until vegetation is established. Vegetation shall be undisturbed after it has become established. Slope, Embankment, (z) Regrade, repair, and revegetate eroded As needed, based on damage and Outlet Stabilization and slumped banks. observed during inspections. Debris and Litter Control Keep the area clean to reduce litter and Annually, and after major storm events, clean debris and floatables being washed downstream. litter which has accumulated. Mechanical Components Not Applicable Not applicable Insect Control Normally not applicable. Normally not applicable. Access Road and Area Normally not applicable. Normally not applicable. Maintenance Sediment and Pollutant Normally not applicable. If heavy accumulations of sediment occur, then either Infrequent Removal remove sediment accumulation or stabilize sediment accumulation in place with top soil and additional vegetation plantings. Component Repair and Normally not applicable. If major areas lose Rare Replacement trees due to fire, disease, or other cause, then replanting may be needed. Note that most herbicides are very toxic to aquatic organisms. Follow listed instructions and never allow spray to enter waterways. (2) If maintenance work is required along the banks of jurisdictional streams or in wetlands, a permit may be required from the U.S. Army Corps of Engineers and the Virginia Department of Environmental Quality. COUNTY OF ROANOKE q U XI1116 14-21 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.3.15 Underground Detention Facilities Underground detention facilities are facilities that provide detention in underground pipes or chambers. For underground detention maintenance guidance, see Table 14.15. Table 14.15 Underground Detention Maintenance Required Action Maintenance Objective Frequency of Action Inspections Inspect condition of storage facility, outlet Semiannually structure, and presence of sediment and debris. Vegetation Management Not applicable Not applicable Slope, Embankment, Not applicable Not applicable and Outlet Stabilization Debris and Litter Control Remove debris and litter. As needed based on observations during semiannual inspection. Mechanical Com onents Not applicable Not applicable Insect Control Not applicable Not applicable Access Road and Area Maintenance Not applicable Not applicable Sediment and Pollutant Removal Remove accumulated sediments and Varies, depending on the dispose of them in an upland location and effectiveness of the pretreatment device. stabilize with vegetation. Component Repair Replace failed pipe, storage chambers, or Rare and Replacement other com onents. COUNTY OF ROANOKE q 1 X11/16 14-22 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES CHAPTER 14 14.4 Additional Maintenance and Repairs The routine maintenance items listed in the Maintenance Agreement are the minimum measures If actual conditions demonstrate that additional maintenance or repairs are necessary for proper functioning of the stormwater management systems, they shall be provided by the responsible party - 14.5 Inspection and Maintenance Records The responsible party or property owner shall maintain records of stormwater management facilities' inspections and maintenance activities, and submit copies to the County, when requested. 14.6 References The VA SWM Handbook and VA BMP Clearinghouse website 4a& -contain information on maintenance of all VA DEQ approved nonproprietary BMPs- r, Ai4#,.:r:r c. -+P . . S3,Ste+H n n_..:,7,.t�,.,.v sem,- v„ . A*8 OW -Refs a*d n.. C',.,- 41A ..r ............ ..C...iA'ate BN44-21; n4q.7 ♦7.:.. ,7,.,...m -eq* : ,.1..,7,.,7 4 n....,...,7:., 1 4B COUNTY OF ROANOKE 9 U XI1/16 14-23 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A APPENDIX 14A MAINTENANCE AGREEMENTS Stormwater Management/BMP Facilities — Sample Maintenance Agreement can be found at http://Www.roanokecomtyva.gov/index.aspx?NID-331 Maintenance Agreements shall be submitted to: Department of Community Development Roanoke County Administration Center 5204 Bernard Drive P.O. Box 29800 Roanoke, VA 24018-0798 Procedures for submitting agreements: • Type all information on the agreement form. • Authorized property owner must sign form in black ink. • Signature must be properly notarized lack IiD. • Attach a check for the recordation fee. • The Department of Community Development will coordinate the County Attorney and County Executive signatures, and recordation. • Maintenance agreements are required to be submitted, approved, and executed prior to the pre -construction meeting. COUNTY OF ROANOKE 9 /�/t dx/1/16 14A-1 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A A444 l.RA 140f@i+f.#,.4. ,...110,1 ♦1.,. AN R A C 448 T ....,1,.11 .. ♦1.,. ,. 14 F,.,... „10 ,.F e eft,.:.. ,,.,.1 ,. ,.,.r., ,1,...,.,.:1.04 Off aS f8effElOd 1.., ,1804 4 440 1..44,1 , ,.,.,1.. „F -,.....RkR G -.IM#)', 3AF`qi+l:�1..4,..,.1.,...�T 1.�.1.RW. ,.:....A�. ,...11,.,1 R.,. "D,.,,„,,,.r., ” 3A7uL`RVL 48 -cr�cC too Site �j1,1�:1.:�yl k44RW...S 37< U] UL' 48, 440 D,.,,„,,,•r., ..r..:......rOf „r F..,1:1:ti Rq COUNTY OF ROANOKE 74V -1-4x/1/16- 14A-2 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A COUNTY OF ROANOKE ;444X/1/16- 14A-3 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A COUNTY OF ROANOKE ;444X/1/16- 14A-4 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A COUNTY OF ROANOKE 14x/1/16 14A-5 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A COUNTY OF ROANOKE 14x/1/16 14A-6 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A COUNTY OF ROANOKE 14x/1/16 14A-7 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A .- - - j Formatted: Left COUNTY OF ROANOKE 14x/1/16 14A-8 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A c00 *hR c*RVMFA, tof Nfafi.,.,.. oq* - ,nwii:. n , R. F fogoifements at .- - - Formatted: Centered COUNTY OF ROANOKE 9/1-1 dx/1/1(r 14A-9 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A Right �P,hgd.lal@ .- - - Formatted: Centered AVOR COUNTY OFROANOKE 9 U dx/1/1(r 14A-10 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14A .- - - Formatted: Centered, Indent: Hanging: 0.5, Tab stops: t 0.38", Left + 0.75', Left + 3.25', Centered Formatted: Centered website.) COUNTY OF ROANOKE 9 U dx/1/1(r 14A-11 MAINTENANCE MAINTENANCE OF STORMWATER MANAGEMENT FACILITIES APPENDIX 14B .- - - Formatted: Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Centered, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers - - Formatted: Adjust space between Latin and Asian text, Adjust space between Asian text and numbers COUNTY OF ROANOKE ;444x/1/16 44914A-1 MAINTENANCE INSPECTION AND ENFORCEMENT CHAPTER 15 Chapter 15 - Inspection and Enforcement Inspection and enforcement can be divided into two distinct categories, construction and pest post -construction. Construction inspection ensures that the storm drainage systems and stormwater management facilities are constructed and installed in accordance with the approved Stormwater Management Plan. Once construction is complete, a final inspection will be conducted, and as -built documentation will be submitted to show that the constructed project meets the requirements of the approved Stormwater Management Plan. At this point, the responsibility for the operation and maintenance of the storm drainage systems and stormwater management facilities is transferred from the permittee to the property owner or responsible party. Where a project is constructed in phases, a final inspection shall be conducted of each completed phase as designated by the approved Stormwater Management Plan. The final inspection shall consist only of the phase being identified as complete. After construction is complete, the property owner or responsible party is required to conduct periodic inspections and maintenance of the stormwater management facilities. Property owner inspections and maintenance activities must be documented and maintained. The County of Roanoke will also conduct periodic post -construction compliance inspections of stormwater management facilities. 15.1 Construction Inspections Construction of storm drainage systems and stormwater management facilities shall comply with the approved final Stormwater Management Plan. Any changes to the approved design require a resubmittal to the County of Roanoke for approval. Inspections shall be performed by the permittee to ensure that construction conforms to the approved plans and specifications. Additional inspections will be performed by the County of Roanoke to confirm compliance. 15.1.1 Notifications to the County of Roanoke The permittee shall notify the County of Roanoke in advance of the start of construction and of the construction of critical components of a stormwater management facility. The following are examples of, but not limited to, critical components: • Before the start of construction; • Before installing a stormwater pond embankment; • Before installing pond outlet structures; COUNTY OF ROANOKE q444x/1/16 15-1 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 • Before setting any concrete BMP structures, this does not include precast drop inlets or manholes; • Before installing energy dissipation structures and any outlet structure into a jurisdictional stream (perennial or intermittent flow); • Before installing any infiltration or bioretention BMP; or • Any other key BMP component as determined by the County of Roanoke 15.1.2 Periodic Inspections The permittee is responsible to perform adequate inspection of the construction activities to confirm that the site is in compliance with the Erosion and Sediment Control Ordinance requirements and that the construction of storm drainage systems and stormwater management facilities and BMPs are in conformance with the approved Stormwater Management Plan. Upon completion of construction, the permittee must provide certification from a licensed professional that the completed project is in accordance with the approved plans and specifications and must provide documentation of regular inspections sufficient to adequately support compliance. All permittee inspections shall be documented and written reports prepared that contain the following information: • The date and location of the permittee inspection; • Whether construction is in compliance with the approved Stormwater Management Plan; • Variations from the approved construction specifications; • Corrective actions that have been taken to correct previous violations; • Any violations that exist or corrective actions that have been completed; and • The name and signature of the person who performed the inspection. The County of Roanoke shall conduct periodic inspections during construction. During the County inspection, the permittee will provide all permittee inspections which have been conducted since the last County inspection for County observation. If the County finds any violations, the permittee shall be notified in writing of the nature of the violation and of the required corrective actions. In conjunction, the County may issue an order requiring that all or part of the land disturbing activities permitted on the site be stopped until the specified corrective measures have been taken. If the County of Roanoke determines that there is a repeated failure to comply with the approved plans and specifications, enforcement action may be taken. COUNTY OF ROANOKE q444x/1/16 15-2 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 15.1.3 Final Inspection and As -Built Documentation Prior to final acceptance of the project the permittee is required to submit to the County of Roanoke as -built documentation, confirming that the storm drainage systems and stormwater management facilities and practices that have been constructed conform to the approved Stormwater Management Plan. In addition, once the as -built documentation has been submitted, a final inspection will be conducted by the County of Roanoke to confirm that the as -built documentation conforms to the actual construction. As -built documentation shall include the following: _General: - I Formatted: Font: Bold, Underline • As -built survey conducted following construction, eeedsealed by a —r-egistefe4-Registered 4f4 -Land *ufvey�Surveyor and/or pi:afessianal Professional eegiffeeFEn ing eer. As -built plans shall be a "redline" of the approved plans pr a full size�ecord drawing Sas outlined below) and shall - Formatted: Highlight be to scale and provide a north arrow. Formatted: Highlight Formatted: Highlight • Stormwater easements and access easements shall be shown on the plans with metes and bounds. • Certification statement, signed by the permitee and a Licensed Professional indicating conformance with the approved Stormwater Management Plan (including certification to both the storm drainage and stormwater BMPs are in compliance with the approved plans). • A supplemental digital file is required for County records and shall be provided via the FTP site or on a CD-ROM made available in an AutoCAD format shown with the layer configurations described in Section 15.1.4. Formatted: Not Highlight The permittee's inspection log records with copies of all inspection test results documenting compliance with the approved Stormwater Management Plan. Storm Drain Systems: • All storm system structures identified and labeled the same as the approved plan. All structure elevations are to include an invert elevation, a top of grate (at grade) elevation and any opening elevations used for storm water intake nu noses (NAVD 88). All data is to be verified to the closest hundredth of a foot (0.01 COUNTY OF ROANOKE q444x/1/16 15-3 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 • All storm system pipes identified and labeled the same as the approved plan with upstream and downstream invert elevations (NAVD 88), the total length of the pipe run from end to end, with the calculated slope. All data is to be verified to the closest hundredth of a foot (0.01). • Maximum tolerances shall be based upon the following: 1. Does the structure function properly (i.e. is pipe capacity greater than the calculated flow, etc)? 2. Has the proper amount of cover been provided? 3. Has a minimum as -built slope of 0.40% been provided or O,g greater than 3 fps - , - Formatted: Subscript (whichever is more restrictive). •2edline revision of approved storm drainage profiles and horizontal_ - - - , - Formatted: Font: Bold, underline layout plans for as -built storm drainages Structures. 421..,.,..1 yJgg,.L ......«' .. 1,,., ,7,...:,.., ...liae ... with ..,.414..1 For changed values, strike thru the design value and enter the constructed value i4q red.- • A one page "record drawing". may be provided for the as-builts which - - Formatted: Highlight includes the following information as a minimum: 1. Storm drainage - - - Formatted: Font: Bold, underline, Highlight profiles or storm drainage table which shows structure number, rim, Formatted: Highlight inverts, pipe length, diameter, and slope; and 2. !Horizontal layout of storm Formatted: Highlight drainage on plans (plan should also show the location of buildings, edge of \ ' Formatted: Highlight pavement, sidewalk, curb and gutter, property line, etc). - - Formatted: List Paragraph, No bullets or numbering, Adjust • Label plan sheet as as -built. space between Latin and Asian text, Adjust space between Asian text and numbers, Tab stops: Not at 1.5" BMPs: • Redline of approved Stormwater Management Plan for BMPs_ For -------- Formatted: Font: Bold, underline changed values, strike thru the design value and enter the constructed value. Provide as -built dimensions of the structures, grades, slopes, elevations, BMP components details), etc on the plans to verify that the , - Formatted: Highlight structure has been constructed correctly. A one page record drawing may be provided for the as-builts which F - - Formatted: Indent: Left: 1.25" includes the following information as a minimum: 1. Horizontal layout of Formatted: Font: Bold, underline BMP on plans (plan should also show the location of buildings, edge of pavement, sidewalk, curb and gutter, property line, etc); 2. As -built contours if required (i.e. bioretention); 3. Accessory structure details (i.e. berm, orifice, outlet structure, diaphragms, weirs, soil media, etc.). This should be provided with the BMP details on the as -built plan, , - Formatted: Highlight • Update the BMP table on the plans and label as "as -built". Provide latitude and longitude of as -built BMP. COUNTY OF ROANOKE q444x/1/16 15-4 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 • Provide available Manufacturer certification that the structure was installed correctly. • Label plan sheet as as -built. • A supplemental digital file is required for County records and shall be provided via the FTP site or on a CD-ROM made available in an AutoCAD format shown with the layer configurations described in Section 15.1.4. Ditch and Channel Sections: • Provide ditch/channel cross-sections plotted to scale, 300 feet maximum intervals or portion thereof, minimum of 2 per ditch, with adequate spot elevations that defines the ditch section and slope as required by the approved plan. Label distances between spot elevations on the cross sections. The Engineer shall show the location on the swale where the cross section is being provided. • Cross sections are to be shown and labeled on the plan. • Maximum tolerances shall be based upon the following: 1. Does the structure function properly (i.e. is swale capacity greater than the calculated flow, etc)? 2. Has the proper amount of depth/freeboard been provided? 3. Has a minimum as -built slope of 2.0% been provided vegetated swales or 1.0% for riprap or concrete lined channels? 4. Has the maximum allowable velocitv for the channel lining been exceeded? • A supplemental digital file is required for County records and shall be provided via the FTP site or on a CD-ROM made available in an AutoCAD format shown with the layer configurations described in Section 15.1.4. Ponds: • Redline of approved Stormwater Management Plan for ponds. For _ - changed values, strike thru the design value and enter the constructed value. Provide as -built dimensions of the structures, pipe.slopes, berms. _ elevations, pond structure; omponents (details) etc on the plans to verify that the structure has been constructed correctly. • A one page "record drawing" may be provided for the as-builts which includes the following information as a minimum: 1. Horizontal layout of COUNTY OF ROANOKE q444x/1/16 15-5 INSPECTION AND ENFORCEMENT Formatted: Highlight Formatted: Highlight Formatted: Highlight Formatted: Highlight Formatted: Highlight Formatted: Highlight Formatted: Indent: Left: 1.5', No bullets or numbering INSPECTION AND ENFORCEMENT CHAPTER 15 pond on plans (plan should also show the location of buildings, edge of pavement, sidewalk, curb and gutter, property line, etc); 2. As -built contours; 3. Accessory structure details (i.e. berm, orifice, outlet structure, weirs, etc.). This should be provided with the pond details on the as -built plan. • The survey shall include enough information to verify that storage capacities are no less than the storage volume required by the approved Stormwater Management Plan. For retention and detention structures, a stage -storage summary table with design values and as -built values shall be included. The survey shall verify inverts and sizes of pipes, culverts, and outlet structures. r,r,..,:mWm_ tole,.,.44, e " hnil be 41 n ' r�R* 4 r • Show location of and label elevations and width of berm. • Show location and label dimension and elevations of spillways. • Label Dlan sheet as as -built. • A supplemental digital file is required for County records and shall be provided via the FTP site or on a CD-ROM made available in an AutoCAD format shown with the layer configurations described in Section 15.1.4. If it is determined from the as -built documentation that the storm drainage systems and or the stormwater management BMP facilities have not been constructed in accordance with the approved Stormwater Management Plan, then corrective action will be taken to comply with the approved Plan or the permittee shall provide studies and information required by the County of Roanoke to demonstrate that the constructed systems will function equivalent to the approved Stormwater Management Plan. This includes meeting all flow, velocity, and regulatory requirements and that the approved elevation -storage requirement is maintained. Once the as -built documentation has been accepted by the County of Roanoke, the permittee shall schedule a final inspection of the project site prior to final acceptance of the project by the County and the return of performance bonds or securities. The permittee shall provide 48 hour notice of a final inspection to the County of Roanoke. 15.1.4 ACAD Digital File Requirements The following items shall be submitted in ACAD format with the as-builts. All items shall be tied to the State Plane Coordinate and NAVD 88. All items shall COUNTY OF ROANOKE q444x/1/16 15-6 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 be set to an elevation of zero, unless otherwise noted. All items (storm,_topo- _ _ _ - - I Formatted: Highlight pavement, etc.) shall be submitted on a standalone layer (applicably named) so - _ Formatted: Highlight that information can correctly incorporated in to County GIS. • Storm drainage pipe and structures. Structures shall be shown at their as - built location. • Stormwater BMPs shown at the as -built location. BMPs shall be labeled to match the plans. Ponds, swales, infiltration basins, etc shall provide as - built contours and have applicable elevation assigned to the line work. • Proposed Ttopographic contours inside the site property boundary for the approved proiect. These contours are the line work as shown on the approved plans and are not as -built contours, but line work from the CAD drawings. Elevations shall be assigned to the line work. • Easements and right-of-ways. • Property lot lines. • Edge of pavement. • Building layout. 15.2 Post -Construction Inspections and Maintenance The property owner or responsible party is responsible for the proper operation, inspection, maintenance, and repair of stormwater management facilities, after the completion of construction, in accordance with the applicable maintenance agreement. All inspection, maintenance, and repair activities shall be documented. The responsible party shall inspect and maintain stormwater management facilities at the frequencies listed in the Maintenance Agreement, - In addition to the inspections performed by the responsible party, each stormwater management facility will be inspected periodically by the County of Roanoke. In the event that the stormwater management facility has not been maintained and/or becomes a danger to public safety, public health, or the environment, the County of Roanoke shall notify the property owner, or responsible party, by registered or certified mail and issue a Notice of Violation. The Notice shall specify the measures needed to correct the situation and shall specify the time within which such measures must be completed. If the responsible party fails or refuses to meet the requirements of the maintenance agreement, the County of Roanoke, after reasonable notice, may apply a civil or criminal penalty and may correct a violation of the design standards or maintenance needs by performing all necessary work to place the facility in proper working condition, and recover the costs from the responsible party or property owner. 15.3 Records Parties responsible for the operation and maintenance of a stormwater management facility shall make records of the installation and of all inspections, maintenance and COUNTY OF ROANOKE q444x/1/16 15-7 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 repairs, and shall retain the records for at least five (5) years. These records shall be made available to the County of Roanoke upon request. Examples of (inspection records can be found on the BMP Clearinghouse website, in Appendix 15A, or obtained from Manufacturer literature. 15.4 Enforcement Any activity that is commenced without an approved Stormwater Management Plan, or is conducted contrary to the approved Stormwater Management Plan, may be subject to the enforcement actions outlined in the County of Roanoke Stormwater Management Ordinance. A property owner or responsible party that does not properly maintain a stormwater management facility in accordance with the maintenance agreement may be subject to the enforcement actions outlined in the County of Roanoke Stormwater Management Ordinance. 15.4.1 Notice of Violation When a County of Roanoke inspection has noted that a construction activity or maintenance of a stormwater management facility is not in compliance with the approved Stormwater Management Plan, including all maintenance agreements, or the County of Roanoke Stormwater Management Ordinance, the County shall issue a written notice of violation delivered by registered or certified mail to the permittee or property owner. The notice of violation shall include: • The name and address of the responsible party; • The address when available or a description of the building, structure or land upon which the violation is occurring; • A statement specifying the nature of the violation; • A description of the remedial measures necessary to correct the violation and a time schedule for the completion of such remedial action; • A statement of the penalty or penalties that may be assessed against the person to whom the notice of violation is directed, should the remedial measures not be implemented; • A statement that the determination of violation may be appealed by filing a written notice of appeal within 30 days of service of notice of violation. COUNTY OF ROANOKE q444x/1/16 15-8 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT CHAPTER 15 15.4.2 Stop Work Orders If a project site is under construction and receives a notice of violation, construction activities in the area where the work was found to be deficient in meeting the approved Stormwater Management Plan shall cease immediately. The stop work order will be in effect until the County of Roanoke confirms that the land disturbing activity is in compliance with the approved Stormwater Management Plan. The permittee shall address the remedial measures published with the notice of violation within the time period specified. Upon completion of the remedial measures, the County of Roanoke shall inspect the work and authorize the permittee in writing that the stop work order has been removed and work may continue in that area of the project. Failure to comply with a stop work order or with a notice of violation may result in the revocation of the permit and the violator shall be subject to the penalties set forth by the Stormwater Management Ordinance. 15.4.3 Restoration of Lands Any violator may be required to restore land to its undisturbed condition in accordance with a notice of violation, stop work order, or permit requirements. In the event that restoration is not undertaken within the time specified in the notice, the County of Roanoke may take necessary corrective action, the cost of which shall be covered by the performance bond, or become a lien upon the property until paid, or both. COUNTY OF ROANOKE q444x/1/16 15-9 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A APPENDIX 15A INSPECTION FORMS Stormwater Management Construction Inspection Checklist Stormwater Management Facilities Inspection Report Form Stormwater Management Facilities Maintenance/Repair Report Form COUNTY OF ROANOKE q444x/1/16 15A-1 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A Stormwater Management Construction Inspection Checklist Inspector Name: Permittee's Name: Site Address or Location: Watershed: Reason for Inspection: ❑ Routine Inspection ❑ Complaint Disturbed Area (at time of inspection): Does the Site Require: ❑ Erosion and Sediment Control Plan Inspection Date: Permit Number: Tax Map or Parcel ID No: ❑ Intensive Rainfall ❑ Other ❑ Stormwater Pollution Prevention Plan ❑ SPCC Plan (oil storage) ❑ Other If required, are these plans or permits available on-site? Erosion and Sediment Control Item Used Acceptable Observations and Completion Condition Actions Required Date Silt Fence Y ❑ N ❑ Y ❑ N ❑ Straw Bales Y ❑ N ❑ Y ❑ N ❑ Inlet Protection Y ❑ N ❑ Y ❑ N ❑ Stabilized Construction Entrance Y ❑ N ❑ Y ❑ N ❑ Sediment Trap/Basin Y ❑ N ❑ Y ❑ N ❑ Check Dams Y ❑ N ❑ Y ❑ N ❑ Seeding (Temporary or Final) Y ❑ N ❑ Y ❑ N ❑ Other: Y ❑ N ❑ Y ❑ N ❑ Y❑ N❑ Y❑ N❑ Y 1 N 1 Y 1 N 1 Y 1 N 1 Y 1 N 1 Page 1 of 2 COUNTY OF ROANOKE q444x/1/16 15A-2 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A Date �n�rn a Stormwater Collection and Transport (Culverts, Storm Drains, and Inlets) Item Constructed as Approved? Discrepancies and Corrections Completion Date Y❑ N❑ Y 1 N 1 Y 1 N 1 Y 1 N 1 Y 1 N 1 Y❑ N❑ Y 1 N 1 Y 1 N 1 Discharge Outfall from Development Adequate channel: Y❑ N❑ Signature of Inspector Page 2 of 2 COUNTY OF ROANOKE q444x/1/16 15A-3 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A inspection Ghp0dist .- - - Formatted: Centered COUNTY OF ROANOKE q444x/1/16 15A-4 INSPECTION AND ENFORCEMENT - Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered - - Formatted: Centered FnrmattM! Centere`i Formatted: Centered 3-7- 1 No —POR. thR ..t«..,.t..«o ..1.,... S gHS ..F soul:...,. ,.«..ekiri,. 1...1..:ng, a _ Do embankments, spil4ways, side slopesffl eta Outl otos -cast-ccnoo ��JI ��JI ��JI Is dgRrR 0..,70«,.0 ,.F ..«:.......1 7..tt.ere woody vegetation gfo.. h t7...t may iatefforewith th o FI,... .. is 4aofe a build up of Appmig .. t1.o«o o :ao«,.o ,.F� T :...... rOpo«..,. wifi fie proper eporatisA9 44 I's HfBf*! Br 84hof na1 06 J COUNTY OF ROANOKE q444x/1/16 15A-4 INSPECTION AND ENFORCEMENT - Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered Formatted: Centered - - Formatted: Centered FnrmattM! Centere`i Formatted: Centered INSPECTION AND ENFORCEMENT APPENDIX 15A Page 4- of 3I COUNTY OF ROANOKE q444x/1/16 15A-5 INSPECTION AND ENFORCEMENT Checked Maintenance Item Inspected Observations and Remarks Yes No Reqd. Not Req. Culverts and Storm Drains Is the culvert or storm drain filled more than 25% with debris, El 11 E] sediment, or trash? Is there evidence of structural El 11 11failure 11 of the culvert pipe? Is there evidence of erosion at the inlet and outlet of the culvert or at the storm drain inlet? Are there signs of settling, cracking, or misalignment of ❑ ❑ ❑ culverts, storm drain pipe, or concrete inlets? Stormwater Ponds (see also Embankments) Is the emergency spillway clear of obstructions, debris, and vegetation? Is the outlet structure and pipe clean of debris and sediment, free L1 0' L1 11 of damage, and in working order? Is there an accumulation of debris, ❑ litter or trash? (For dry detention ponds) Is there ❑ El 11standin water in the pond? (For wet ponds) Is their excessive 11 El 11 11algae growth or other vegetation' Is there evidence of oil or other ❑ ❑ ❑ ❑ pollutants in thepond? Is there erosion at the discharge ❑ ❑ ❑ point? Do any safety devices, fences, ❑ ❑ ❑ ❑ gates, or locks need repair, 0+40,. ur,ry SANd -Fila F fia c., -,,,.,,,e-4 Ts +4ere , oa:,,.o..+ ,lObri litter, 4+. e l + 40 oil,..«+«...4 +.. ieas68e9 4-4 -4 �te�? 44 44 44 4 Is �-S' 44 -4 44 4 oat+a4w,-orvrrr..« e.,49 Page 4- of 3I COUNTY OF ROANOKE q444x/1/16 15A-5 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A STORMWATER MANAGEMENT BMP FACILITIES INSPECTION REPORT FORM Inspection Requirements: See the Stormwater Management BMP Facilities Maintenance Schedule for landowner's responsibilities for frequency of inspection and other requirements. This information is a part of the Maintenance Agreement that is recorded in the land records with the deed. Inspection Purpose: To assure safe and proper functioning of the stotmwater management BMP facilities and associated structures, by providing regular observations of their conditions and operation. Retention of Records: All inspection/maintenance/repair documentation shall be retained by the landowner for a minimum of five (5) years. Submission of Records: At the end of each year, by December 31 ', mail all BMP inspection and maintenance documentation to: County of Roanoke Department of Community Development 5204 Bernard Drive Roanoke, Virginia 24018 Attention: Stormwater Program Managers (BMP Inspection - - Formatted: Indent: First line: 0" and Maintenance Records) NAME OF BUSINESS OR LANDOWNER-- ADDRESS: ANDOWNER ADDRESS: INSPECTION DATE: PERFORMED BY: Facility Management Checklist The following items should be checked for each BMP: COUNTY OF ROANOKE q444x/1/16 15A-6 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A 1. Facility construction meets the requirements of the Roanoke County Stormwater Management Design Manual, where applicable, and is adequate for the intended function. 2. The facility has been maintained properly according to the requirements of the Recorded Maintenance Agreement, BMP Maintenance Schedule, and the Roanoke County Stormwater Management Design Manual. 3. The facility is functioning adequately. 4. There have been no changes to the site conditions or area that would require modification and/or replacement of the existing facilities. 5. Access to the facility is adequate and maintained. Sheet 1 of COUNTY OF ROANOKE q444x/1/16 15A-7 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A .- - - Formatted: Centered - - Formatted: Centered, Tab stops: -0.84", Left + -0.5", Left h + 0", Left + 0.38", Left + 0.5", Left + 0.75", Left + 1 v rT Left + 1.5", Left Formatted: Centered .a—.a - - Formatted: Centered, Indent: Left: 0", First line: 0", Tab stops: 0", Left + 0.5", Left + 1", Left + 1.5", Left ReL1+rireizA14s to Cense n aa:.:,.B,.i Sheet of COUNTY OF ROANOKE q444x/1/16 15A-8 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A STORMWATER MANAGEMENT BMP FACILITIES MAINTENANCE/REPAIR REPORT FORM Maintenance Requirements:_ Refer to the site's Stormwater Management BMP Facilities Maintenance Schedule for landowner's responsibilities for frequency of maintenance and other requirements. This Maintenance Schedule is a guideline of minimum maintenance requirements. Additional maintenance shall be performed as necessary for the proper functioning of Stormwater Management BMP facilities. This information is a part of the Maintenance Agreement that is recorded in the land records with the deed Maintenance Purpose: To enable the proper long-term functioning of the stormwater management BMP facilities to protect the Valley's water quality and prevent downstream flooding. Retention of Records: All inspection/maintenance/repair documentation shall be retained for a minimum of five (5) years. Submission of Records: At the end of each year, by December 31 ', mail all BMP inspection and maintenance documentation to: County of Roanoke Department of Community Development 5204 Bernard Drive Roanoke, Virginia 24018 Attention: Dewe'..,... eR ReviewStormwater Program Manager r'O�taF (BMP Inspection and Maintenance Records) NAME OF BUSINESS OR LANDOWNER: ADDRESS: MAINTENANCE/REPAIR DATE: PERFORMED BY: GENERAL COMMENTS: COUNTY OF ROANOKE q444x/1/16 15A-9 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A Sheet 1 of COUNTY OF ROANOKE q444x/1/16 15A-10 INSPECTION AND ENFORCEMENT INSPECTION AND ENFORCEMENT APPENDIX 15A .- - - Formatted: Tab stops: Not at -0.84" + REFER TO THE RECORDED AirA INTEN A NGE A/ REEAA ENT DAA U AiT A NTEN A1�TG + 1" + 1.5" Sl1.Z ST-ORA43AZATER A44NAGRAUAT RAW VAC -41 IT -1 - - Formatted: Centered, Tab stops: Not at 0" + 0.5" + 1" + 1.5" — - - j Formatted: Centered, Tab stops: 0.38", Left + 0.75", Left COUNTY OF ROANOKE q444x/1/16 15A-11 INSPECTION AND ENFORCEMENT ACTION NO. ITEM NO. F-1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Ordinance accepting and appropriating $4,000 for printing costs of the K, 1, and 2 grade level instructional materials to support the County literacy plan SUBMITTED BY: APPROVED BY: Rebecca Owens Director of Finance Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: The County literacy plan is a K through 12 program for students who are not reading at the appropriate age level to improve their reading skills. The program is funded, at least in part, by the sale of used textbooks. Funds are used for program materials. In August 2015, the Roanoke County Schools Instructional Resources Department held a used textbook sale. The $38,200 of revenue generated from the sale exceeded the appropriated budget by $33,200. The department is requesting $4,000 of the excess revenues be appropriated to cover the printing costs of instructional materials and purchase of the purchase of spiral bound books. Excess revenue will be reserved. FISCAL IMPACT: Collections from the sale of textbooks in the amount of $4,000 needs to be appropriated to cover the printing costs for instructional materials. STAFF RECOMMENDATION: Staff recommends approval of the first reading of this ordinance and scheduling of the second reading on March 22, 2016. Page 1 of 1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 ORDINANCE ACCEPTING AND APPROPRIATING $4,000 FOR PRINTING COSTS OF THE K, 1, AND 2 GRADE LEVEL INSTRUCTIONAL MATERIALS TO SUPPORT THE COUNTY LITERACY PLAN WHEREAS, the County literacy plan is a K through 12 program for students that outlines how to teach students who are not reading at the appropriate age level to improve their reading skills; and WHEREAS, in August 2015 the Roanoke County Schools Instructional Resources Department held a used textbook sale and generated revenues from the sale that exceeded the appropriated budget by $33,200; and WHEREAS, the department is requesting $4,000 of the excess revenues be appropriated to cover the printing costs of the K, 1, and 2 grade level instructional materials to support the county literacy plan; and WHEREAS, spiral bound books will be purchased and all materials printed will last a number of years; and WHEREAS, Section 18.04 of the Roanoke County Charter provides that funds be appropriated by ordinance; and WHEREAS, first reading of this ordinance was held on March 8, 2016, and the second reading was held on March 22, 2016. BE IT ORDAINED by the Board of Supervisors of Roanoke County, Virginia, as follows.. Page 1 of 2 That the sum of $4,000 is hereby appropriated to the Roanoke County Public Schools; and 2. That this ordinance shall take effect from and after the date of adoption. Page 2 of 2 ACTION NO. ITEM NO. F-2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: SUBMITTED BY: APPROVED BY: Ordinance accepting and appropriating funds in the amount of $27,500 to the Roanoke County Public Schools from the National Board for Professional Teaching Standards for teacher incentives Rebecca Owens Director of Finance Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: The Roanoke County Public Schools has received an award of $27,500 that needs Board appropriation. The General Assembly provides funds to award incentives to teachers in Virginia's public schools who hold certifications from the National Board for Professional Teaching Standards and meet the specified criteria. The National Board Certification Bonus award is $27,500 for the funding period July 1, 2015 to June 30, 2016. Eleven (11) teachers in the Roanoke County Public Schools will receive a $2,500 incentive for holding their National Board certifications and meeting the specified criteria. The incentive is taxable to the recipient and the school division assumes responsibility for ensuring all taxes are remitted. FISCAL IMPACT: The State will provide one hundred percent (100%) funding for the incentives. No funds from Roanoke County Public Schools are required. Page 1 of 2 STAFF RECOMMENDATION: Staff recommends approval of the first reading of this ordinance and scheduling of the second reading on March 22, 2016. Page 2 of 2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 ORDINANCE ACCEPTING AND APPROPRIATING FUNDS IN THE AMOUNT OF $27,500 TO ROANOKE COUNTY PUBLIC SCHOOLS FROM THE NATIONAL BOARD FOR PROFESSIONAL TEACHING STANDARDS FOR TEACHER INCENTIVES WHEREAS, the General Assembly provides funds to award incentives to teachers in Virginia's public schools who hold certifications from the National Board for Professional Teaching Standards and meet the specified criteria; and WHEREAS, eleven (11) teachers in the Roanoke County Public Schools will receive a $2,500 incentive for holding their National Board certifications and meeting the specified criteria; and WHEREAS, the incentive is taxable to the recipient and the school division assumes responsibility for ensuring all taxes are remitted; and WHEREAS, Section 18.04 of the Roanoke County Charter provides that funds be appropriated by ordinance; and WHEREAS, first reading of this ordinance was held on March 8, 2016, and the second reading was held on March 22, 2016. BE IT ORDAINED by the Board of Supervisors of Roanoke County, Virginia, as follows.. 1. That the sum of $27,500 is hereby appropriated to the Roanoke County Public Schools; and 2. That this ordinance shall take effect from and after the date of adoption. Page 1 of 1 ACTION NO. ITEM NO. F-3 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Ordinance accepting and appropriating funds in the amount of $2,300 to the Roanoke County Public Schools from Share Our Strength and the Virginia No Kid Hungry Campaign to expand the breakfast program at Northside High School SUBMITTED BY: APPROVED BY: Rebecca Owens Director of Finance Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: The Roanoke County Public Schools Nutrition Department was awarded a grant of $2,300 from Share Our Strength and the Virginia No Kid Hungry Campaign to support the expansion of the breakfast program at Northside High School. The grant funds of $2,300 will be spent on a mobile vending cart that will allow staff to serve meals outside the cafeteria. It is anticipated the cart will increase participation and help support the goal of providing healthy meals to as many students as possible. FISCAL IMPACT: The State will provide one hundred percent (100%) funding. No funds from Roanoke County Public Schools are required. STAFF RECOMMENDATION: Staff recommends approval of the first reading of this ordinance and scheduling of the second reading on March 22, 2016. Page 1 of 1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 ORDINANCE ACCEPTING AND APPROPRIATING FUNDS IN THE AMOUNT OF $2,300 TO THE ROANOKE COUNTY PUBLIC SCHOOLS FROM SHARE OUR STRENGTH AND THE VIRGINIA NO KID HUNGRY CAMPAIGN TO EXPAND THE BREAKFAST PROGRAM AT NORTHSIDE HIGH SCHOOL WHEREAS, the Roanoke County Public Schools Nutrition Department was awarded a grant of $2,300 from Share Our Strength and the Virginia No Kid Hungry Campaign to support the expansion of the breakfast program at Northside High School; and WHEREAS, the grant funds will be spent on a mobile vending cart that will allow staff to serve meals outside the cafeteria; and WHEREAS, it is anticipated the cart will increase participation and help support the goal of providing healthy meals to as many students as possible; and WHEREAS, Section 18.04 of the Roanoke County Charter provides that funds be appropriated by ordinance; and WHEREAS, first reading of this ordinance was held on March 8, 2016, and the second reading was held on March 22, 2016. BE IT ORDAINED by the Board of Supervisors of Roanoke County, Virginia, as follows.. That the sum of $2,300 is hereby appropriated to the Roanoke County Public Schools; and 2. That this ordinance shall take effect from and after the date of adoption. Page 1 of 1 ACTION NO. ITEM NO. F-4 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Ordinance authorizing the conveyance of the Roland E. Cook Building to Old School Partners, LLC SUBMITTED BY: Ruth Ellen Kuhnel County Attorney APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: This is the first reading of an ordinance authorizing the conveyance of the Roland E. Cook Building to Old School Partners, LLC. The Board of Supervisors approved a Performance Agreement on August 11, 2015, and an Option to Purchase agreement on August 25, 2015, with Old School Partners to redevelop the former Roland E. Cook school building. Background: In May of 2014, Roanoke County advertised a Request for Proposals for the sale and redevelopment of the former Roland E. Cook building located in the Town of Vinton. The County received and accepted a proposal from Old School Partners, LLC to purchase and redevelop the facility into a mixed-use residential/commercial development. The proposed mixed-use re -development project includes the establishment of 21 upscale loft apartments (15 one bedroom and 6 studio), with commercial components to be determined during the rezoning process. The Roland Cook building was constructed in 1915, and was used as an educational training facility from 1915-2009. The two story building consists of 17,642 sq. ft. on 1.046 acres, within walking distance to downtown Vinton. Page 1 of 2 To facilitate the redevelopment and historic preservation of the building, the County submitted an application to the Virginia Department of Historic Resources in January of 2015 to determine the facility's eligibility for inclusion in the National Register of Historic Places and the Virginia Landmarks Register. The County received notification in March of 2016 that it has received conditional approval for Part 2 of the application for inclusion in the National Register, which is the final step in a three-part process before the tax credits are issued. FISCAL IMPACT: This redevelopment project will allow the County to avoid long-term operating and facility maintenance costs, while realizing future tax revenues from the projected $3.2 million in property improvements. ALTERNATIVES: 1) Adopt the ordinance authorizing the sale of the Roland E. Cook building to Old School Partners, LLC. 2) Decline to adopt the Ordinance STAFF RECOMMENDATION: Staff recommends Approval of Alternative 1. Page 2 of 2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 ORDINANCE AUTHORIZING THE COOK ELEMENTARY SCHOOL PARTNERS, LLC CONVEYANCE OF ROLAND E. PROPERTY TO OLD SCHOOL WHEREAS, the Board of Supervisors of Roanoke County acquired this property located in Vinton Magisterial District through a conveyance from the Roanoke County School Board by deed dated August 13, 2013. At the time of the conveyance from the School Board to the County, the Roland E. Cook Elementary School ("School") was no longer in use by the Roanoke County School Board and was considered surplus property; and WHEREAS, the Old School Partners, LLC ("Buyer") proposed a purchase of the School for the purpose of restoration and renovation of the School; and WHEREAS, the School is a landmark building in the County, and Buyer's proposal would preserve the historic nature of the building and also provide additional residential and commercial services and employment in the Vinton Magisterial District; and WHEREAS, the County and Buyer executed an Option to Purchase Agreement for the Roland E. Cook Elementary School ("the School") building and parcel of land on August 25, 2015; and WHEREAS, the County, the Roanoke County Economic Development Authority ("EDA"), and the Buyer entered into a Performance Agreement dated August 11, 2015, which set forth terms and conditions for the Buyer's purchase, restoration and renovation of the School Page 1 of 3 WHEREAS, this property is on Tax map numbers 60.16-09-39 and 60.16-0940 and designated as "All those certain parcels of real estate known as the "Roland E. Cook Elementary School" containing 1.0445 acres, more or less, situate in the Vinton Magisterial District, together with any improvements thereon, rights incident thereto, and appurtenances thereon belonging, all as shown on the plat entitled "Boundary survey for School Board of Roanoke County showing Lots 8 through 14 (DB 6, PG 264) Section 8, Map of Lots Belonging to the Vinton Land, Loan & Building Co. (PBI, PG5) to be conveyed to the Board of Supervisors of Roanoke County" prepared by Caldwell White Associates dated August 7, 2013 and recorded as Instrument #20 1313 868," on the Option to Purchase Agreement executed between the County and the Buyer; and WHEREAS, the Option Agreement required the County to apply to the Commonwealth of Virginia Department of Historic Resources ("DHR") for a Historic Preservation Certification and the County made such application to seek a listing of the School on the Virginia Landmarks Register and the National Register of Historic Places ("the Register"); and WHEREAS, the County has applied for and anticipates receiving the appropriate designations from the DHR prior to the conveyance of the School to Buyer; and WHEREAS, the designation of the School on the National Register of Historic Places and on the Virginia Landmarks Register has a significant fiscal impact on the ability of Buyer to finance the renovations of the School through the sale of historic tax credits, which credits are available only in the renovation of those structures designated on the National and Virginia Registers; and WHEREAS, Buyer has agreed that, subsequent to this conveyance, Buyer will Page 2 of 3 assume all responsibility to ensure that the restoration, renovation and maintenance of the School is in compliance with requirements established by the Virginia and National Registers; and WHEREAS, the County authorizes the Buyer to stand in its stead or as its proxy in ongoing agreements and negotiations with DHR with regard to the restoration, renovation and maintenance of the School so that Buyer may obtain historic tax credits; and WHEREAS, the conveyance of this surplus school property for restoration and renovation provides economic benefits to the County and preserves a historic landmark in the County; and WHEREAS, Section 18.04 of the Roanoke County Charter directs that the acquisition and conveyance of real estate interests be accomplished by ordinance; the first reading of this ordinance was held on March 8, 2016, and the second reading and public hearing were held on March 22, 2016. NOW, THEREFORE, BE IT ORDAINED by the Board of Supervisors of Roanoke County, Virginia, as follows: 1. That the County shall convey to Buyer the School property parcels, which consists of Tax map numbers 60.16-09-39 and 60.16-0940, by Deed, a copy of which is attached hereto and incorporated by reference. 2. That the County Administrator or Assistant County Administrator are hereby authorized to execute such documents and take such actions on behalf of Roanoke County in this matter as are necessary to accomplish the acquisition of this real estate, all of which shall be approved as to form by the County Attorney. Page 3 of 3 Molly Joseph Ward Secretary, of Natural Resources February 1oa', 2016 Thomas G. Gates Roanoke County 5204 Bernard Drive Roanoke, VA - 24018 COMMONWEALTH of VIRGINIA Department of Historic Resources 2801 Kensington Avenue, Richmond, Virginia 23221 Re: Roland E. Cook Elementary School - Vinton Amendment #1 Response DHR # 2015-186 Mr. Gates - Julie V. Langan Director Tel: (804) 367-2323 Fax: (804) 367-2391 www.dhr.virginia.gov Thank you for submitting the Continuation/Amendment sheet addressing the additional information requested, and changes to the previously proposed scope of work, for the project at 412 South Poplar Street in Vinton. Based on the materials submitted and the revisions noted on the Amendment, the proposed work is consistent with the Secretary of the Interior's Standards for Rehabilitation and the project is approved provided the below conditions are met. CONDITIONS: The following conditions should be met in order for the project to receive approval. If additional information is requested please submit the materials as an Amendment to the Part 2 application. Otherwise, evidence of the completed, compliant work must be submitted with the Part 3 application. New Doorways on the Primary Elevation - The retention of the character of primary elevations, especially the front primary elevation, is extremely important in a successful Historic Tax Credit Program project. Typically, the proposal to add two new entrances on a primary elevation would not meet the Standards, and so would not be able to be approved. While the creation of doors on this prominent elevation can be approved in this case because of the unique circumstances of this site's topography and existing conditions (which will significantly minimize this work's negative impact on this elevation), a modification to the currently -proposed new door design is needed. As it is currently shown in the submitted elevation drawings, these new doors will be entirely composed of panels of glass in a configuration that mimics the design seen in the historic windows. This work, especially considering all of the windows at this project will be newly installed, may result in a final appearance that makes it seem as if there was always a full -light door here. This would then be in conflict with Standard #3: Administrative Services Eastern Region Office Western Region Office 10 Courthouse Ave. 2801 Kensington Avenue 962 Kime Lane Petersburg, VA 23803 Richmond, VA 23221 Salem, VA 24153 Tel: (804) 862-6408 Tel: (804) 367-2323 Tel: (540) 387-5443 Fax: (804) 862-6196 Fax: (804) 367-2391 Fax: (540) 387-5446 Northern Region Office 5357 Main Street PO Box 519 Stephens City, VA 22655 Tel: (540) 868-7029 Fax: (540) 868-7033 #3: Each property shall be recognized as a physical record of its time, place, and use. Changes that create a false sense of historical development, such as adding conjectural features or architectural elements from other buildings, shall not be undertaken. In order to retain more of the appearance of what was, historically, a window, and to provide the necessary distinction that this new door is, in fact, a new feature, please use a custom-designed door that retains the proportions and configuration of the historic window design, but with an opaque and neutral -colored panel at the bottom that matches the dimensions and general appearance of the historic wall between the window sill and new ground level. Ideally, with this new door design a casual glance at the primary elevation will show a feature that still reads as a window; but upon a closer inspection, it will be clear that this is actually a new door. Cut Sheets of New Windows and Doors - Please submit and Amendment containing cut sheets of all new windows and doors that are to be installed at this site, for review and approval, prior to purchase and installation. A NOTE ON WALLS INTERSECTING WINDOWS AND LOFT SPACES: Please be aware that the ultimate success and appropriateness of these treatments will rely on these new walls and lofts not negatively impacting the overall, exterior visual character of what were historically large expanses of windows that served open classrooms. As a reminder, Standard #i is clear that any new changes that are made to suit a new use must not negatively impact "...the defining characteristics of the building and its site and environment." Should these walls and lofts become very prominent and visible features when seen from the public rights of way, the overall project may no longer meet the Standards and so would not be eligible for participation in the Historic Tax Credit Program. As you know, this conditional approval is for the Part z application and Amendments as submitted, as clarified by the above conditions. All new information or changes to the project scope should be sent to the Virginia Department of Historic Resources in the form of an additional Amendment; you can find the appropriate form through at the National Park Service's website at http://www.nl2s.gov/tps/tax- incentives/application.htm. We have forwarded a copy of Amendment #t to the National Park Service with our recommendation - you will receive their response in a separate letter. Please feel free to contact me with any questions at 804-482-6452 or jessica.Ugarte@dhr.virginia.gov. Sincerely, 4A - Jessica Aurora Ugarte Tax Credit Reviewer Office of Preservation Incentives cc: Katie Cofeld Gutshall Administrative Services Eastern Region Office Western Region Office 10 Courthouse Ave. 2801 Kensington Avenue 962 Kime Lane Petersburg, VA 23803 Richmond, VA 23221 Salem, VA 24153 Tel: (804) 862-6408 Tel: (804) 367-2323 Tel: (540) 387-5443 Fax: (804) 862-6196 Fax:(804)367-2391 Fax: (540) 387-5446 Northern Region Office 5357 Main Street PO Box 519 Stephens City, VA 22655 Tel: (540) 868-7029 Fax: (540) 868-7033 PERFORMANCE AGREEMENT THIS PERFORMANCE AGREEMENT (the "Agreement") is made as of this day of 2015, by and between ROANOKE COUNTY, VIRGINIA, a political subdivision of the Commonwealth of Virginia, (hereafter, the "County"), the ECONOMIC DEVELOPMENT AUTHORITY OF ROANOKE COUNTY, VIRGINIA, a political subdivision of the Commonwealth of Virginia, (hereafter, the "Authority"), and OLD SCHOOL PARTNERS, LLC, a Virginia limited liability company (hereafter, the "Company"). WITNESSETH WHEREAS, the Roanoke County Board of Supervisors and the Economic Development Authority of Roanoke County, Virginia, desire to promote and encourage the economic development and vitality of Roanoke County and the Roanoke Valley through the redevelopment and preservation of historic property in order to provide for retained and increased employment and corporate investment in Roanoke County; and WHEREAS, the Company desires to acquire the old Roland E. Cook Elementary School building, located in the Town of Vinton, that will be redeveloped for the Company's use that will contain twenty-one (21) apartments, including a complete restoration, while maintaining the historic character of the building and incorporating modern conveniences (the "Project") located at 412 S. Poplar Street, Vinton, VA (Tax Map #060.16-09-39 and 40) (the "Property"), and Page 1 of 8 WHEREAS, the County and the Authority expect that the Company will promote economic development and generate new local tax revenues for Roanoke County; and WHEREAS, this increased investment constitutes a valid public purpose for the expenditure of public funds. NOW, THEREFORE, in consideration of the premises and the mutual covenants contained herein, the parties agree to the following: 1. Site Development by the Company. A. The Company will cause this new Project in Roanoke County to be made and developed, subject to obtaining a rezoning of the Property from the Town of Vinton, ordinary and necessary governmental approvals from the County, the approval of historic tax credits, and any other governmental agency. This Project is more specifically described in the Company's September 25, 2014, letter and its "Progress Update Roland E. Cook Project" dated March 23, 2015. S. The Company shall cause the Property to be renovated, restored and constructed into approximately twenty-one (21) apartments while maintaining the historic character of the building and incorporating modern conveniences, as further described in the documents referenced in Section 1.A. above. The estimated project cost (including but not limited to construction and related soft costs) is $3.2 million. The renovation of the Property is scheduled to be completed by June 30, 2017. C. The Company agrees to provide the County and the Authority with any and all documentation {provided that any personally identifiable, private, Page 2 of 8 confidential or other information Company is required by law to keep private, shall be redacted) that may be required to verify the investment figures, during the period in which the Grant payments are to be made pursuant to this Agreement. D. The Company agrees to acquire the Property from the County for $10.00, subject to the terms and conditions set out in an Option Agreement, which is attached to and incorporated into this Performance Agreement. The Company also agrees at its cost and expense: L to prepare a Historic Preservation Certification Application, Part 1 - Evaluation of Significance, and to prepare such other documents as may be necessary to seek the listing of the Property on the National Register of Historic Places; ii. to prepare a historic preservation certification application, Part 2 - Description of Rehabilitation; iii. to work with the Town of Vinton to rezone the property to allow for the proposed uses of this Project; iv. to complete an architectural review of the Property; V. to prepare preliminary construction cost estimates; vi. to explore financing opportunities; vii. to prepare monthly progress reports; and viii. to provide copies of all of these documents to the County. Page 3 of 8 E. The Company anticipates that the source of funds for this Project will include the following: $950,000 from Federal and State Historic Tax Credits, and the remainder from the Company and its private financing. 2. Procedures for the reimbursement of Authority funds to the Company. A. Beginning in calendar year 2016, the County shall appropriate to the Authority sums sufficient for an Economic Development Incentive Grant for the benefit of the Company. These sums sufficient amounts will equal a total of ten (10) years of new local real estate taxes generated by the Project, which is estimated to equal One Hundred and Fifty Thousand Dollars ($150,000.00). The total amount of the Economic Development Incentive Grant shall not exceed $150,000.00. This ten-year period will commence on January 1, 2017. B. Upon receipt of an invoice from the Company, the Authority shall reimburse the Company for its building permit fees imposed by Roanoke County, water and sewer connection fees imposed by the Town of Vinton, and any Erosion & Sediment Control and Stormwater ordinance fees imposed by Roanoke County. C. Within sixty (60) days of the end of each calendar year beginning January 1, 2017 and until December 31, 2026, the Company shall provide such financial and tax data relating to the Project (provided that any personally identifiable, private, confidential or other information Company is required by law to keep private, shall be redacted) as may be reasonably required by the Authority so that the Authority may calculate the actual grant amounts. The Company hereby authorizes the Commissioner of the Revenue for Roanoke County and the Commonwealth of Virginia to release to Page 4 of 8 the Authority and the County the Company's tax information and data so that the Authority may calculate the actual reimbursement amounts. The Authority shall pay the annual reimbursement amount to the Company at an address designated by the Company within thirty (30) days after receipt by the Authority of the data. D. If the Company terminates this Project or fails to complete the construction of this development by June 30, 2017, then the Authority shall be relieved of any obligation to the Company for any Economic Development Incentive Grant. E. If the Company fails to receive historic preservation certification Part 1 and Part 2 and commence construction and renovation activity within one year of execution of this Performance Agreement for the Property, the Company shall be in default of this Performance Agreement and the County may acquire the property together with any improvements made by the Company upon the payment of the sum of Ten Dollars ($10.00); and whereupon the Company shall forthwith convey the property to the County. In the event that the Company fails or refuses to convey title back to the County, then the County shall have the right to enter and take possession of the property. Company shall pay to the County any and all attorney's fees, costs and other expenses incurred as a result of such action. Company agrees not to convey any portion of the property to any other persons or entities until the project is substantially complete; substantial completion shall be determined by the issuance of a certificate of occupancy for the building. If the Company conveys or attempts to convey any portion of the property, this conveyance will be deemed void, of no force or effect, and a breach of this contract and shall automatically revert back to the seller Page 5 of 8 F. Company agrees to provide County with the Additional Performance Security as security for Company's compliance with the terms and conditions of this Performance Agreement and completion of the Project in accordance with Company's Proposal and Plans. Company shall deliver to the County upon receipt of historic preservation certification and before commencing any renovation or construction work on the Property a letter of credit drawn against a bank or other financial institution qualified to, licensed, and conducting business in Roanoke, Virginia subject to prior approval by the County in County's sole discretion. The Additional Performance Security shall be payable to Seller and in the amount of $250,000.00. 3. The Company shall have the right to assign this Agreement to a separate entity provided that any such assignment shall not relieve the Company of its obligations herein. 4. if any party is unable to perform its commitments under this Agreement by reason of force majeure, then that party shall not be deemed to be in default of its obligations under this Agreement, and any deadlines for the performance of its obligations and, if applicable, the deadlines for the performance of the other party's obligations shall be extended for a time equal to the time period of the force majeure event, plus ten days. The term a "force majeure" as used herein, shall include without limitation acts of God: hurricanes, floods, fire, tornadoes, earthquakes, storms; strikes or other industrial disturbances; acts of public enemies; orders of governmental authorities; insurrections; riots; epidemics. Page 6 of 8 5. This Agreement shall be governed by and all disputes related hereto shall be determined in accordance with the laws of the Commonwealth of Virginia. 6. This Agreement and any payments of public funds are subject to future appropriations by the Board of Supervisors to the Authority. IN WITNESS WHEREOF, the undersigned have executed this Agreement the day and year first above written. Approved as to form: Paul M. Mahoney County Attorney STATE OF VIRGINIA ) )ss COUNTY OF ROANOKE ) BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA By: Thomas C. Gates County Administrator The foregoing instrument was acknowledged before me this Z IV - day of 2015, by Thomas C. Gates, County Administrator, on behalf of the Board of Supervisors for Roanoke County, Virginia. Notary Pu1q) Reg. # My Commission expires: �� AUDREY W PALMER Notary Public Commonwealth of Virginia 7098703 My Commission Expires Aug 31, 2015 Page 7 of 8 Approved as to form: ECONOMIC DEVELOPMENT AUTHORITY OF ROANOKE COUNTY By: By: Attorney for EDA Chairm STATE OF VIRGINIA ) )ss COUNTY OF ROANOKE ) The foregoing instrument was acknowledged before me this - -V-1 day of 2015, byChairman of the Economic Development Authority of Roanoke County, Virginia. Notary lic Reg. # My Commission expires: 0; 3,/-61 /tel 5 OLD SCH Its: V STATE OF )ss COUNTY OF L PARTNERS, LLC a f The foregoing instrument was acknowledged before me 2015, Ol chool Partners, LLC. thi day of by \A as �A�N\QQ C" of My Commission expires: � No Public zpiR q,�,'�. eg. # " ty _ P,� �t ���43pG U'• v•� Page 8 of 8 yor pv Q40P� cc; +tiMON �\t:` �. ACTION NO. A-081115-1 ITEM NO. E-2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: August 11, 2015 AGENDA ITEM: Request for authorization to execute a performance agreement between the County of Roanoke, the Roanoke County Economic Development Authority, and Old School Partners, LLC, Vinton Magisterial District SUBMITTED BY: APPROVED BY: Jill Loope Director of Economic Development Paul M. Mahoney County Attorney Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: In May of 2014, Roanoke County issued a Request for Proposals for the sale and redevelopment of the former Roland E. Cook building located in the Town of Vinton. The County received and accepted a proposal from Old School Partners, LLC to purchase and redevelop the facility into a mixed-use development. The proposed development includes the establishment of twenty-one (21) upscale loft apartments (15 one bedroom and 6 studio), with commercial components to be determined during the rezoning process. The Roland Cook building was constructed in 1915, and was used as an educational facility from 1915-2009. The two-story building consists of 17,642 sq. ft. on 1.046 acres, within walking distance to downtown Vinton. The property represents a unique opportunity for redevelopment as a mixed use residential and commercial project. To facilitate the redevelopment and historic preservation of the building, the County submitted an application to the Virginia Department of Historic Resources in January of 2015 to pre- determine the facility's eligibility for inclusion in the National Register of Historic Places and Page 1 of 3 the Virginia Landmarks Register. The County received notification in March that the property received approval at the Preliminary Information Form level (Part 1) and is eligible for this nomination. To assist with the project, a three -party performance agreement has been negotiated between Roanoke County, the Roanoke County Economic Development Authority and Old School Partners, LLC. The agreement provides for reimbursement of permit fees associated with the project. The agreement also provides that a real estate tax revenues generated as a result of redevelopment be returned to the project developer forthe first ten (10) years of the project. The total amount of tax proceeds returned may not exceed $150,000 in total. If the company generates less than the estimated new local tax revenues, then the actual grant for that year shall be less. The ten-year period will commence on January 1, 2017. FISCAL IMPACT: Per the performance agreement, the grant will be calculated as a reimbursement based on new tax revenues generated by the project. The fiscal impact will be in the form of foregone revenue during the agreement period. ALTERNATIVES: 1) Adopt the Performance Agreement authorizing the County Administrator, or any Assistant County Administrator, to execute the Performance Agreement between the County of Roanoke, the Roanoke County Economic Development Authority and Old School Partners, LLC 2) Decline to adopt the Performance Agreement STAFF RECOMMENDATION: Staff recommends Approval of Alternative 1. Page 2 of 3 VOTE: Supervisor Peters moved to approve the request for authorization to execute a Performance Agreement as per the attached agreement. Motion approved. cc: Jill Loope, Director of Economic Development Page 3 of 3 Yes No Absent Ms. Moore ® ❑ ❑ Mr. Bedrosian ® ❑ ❑ Mr. Church ® ❑ ❑ Mr. McNamara ® ❑ ❑ Mr. Peters ® ❑ ❑ cc: Jill Loope, Director of Economic Development Page 3 of 3 Old School Partners, LLC P.O. Box 450 Fincastle, Virginia 24090 December 28, 2015 Thomas C. Gates, County Administrator County of Roanoke P.O. Box 29800 Roanoke, Virginia 24018 1=--1: -3C'P03: z7 PA I TRANSMITTED BY CERTIFIED AND REGULAR MAIL RE: Option to Purchase Agreement dated August 25, 2015 between Roanoke County, Virginia and Old School Partners, LLC for former Roland E. Cook Elementary School Dear Mr. Gates: Pursuant to Paragraph 2 of the Option to Purchase dated August 25, 2015 between Roanoke County, Virginia and Old School Partners, LLC, this letter is notification of Old School Partners, LLC extension of the Option to Purchase through June 30, 2016. Enclosed with this letter is a check for the initial option fee of $500.00 together with a check for the extension fee of $500.00. Thank you for the County's help with this project. Sincerely, OLD SCHOOL PARTNERS, LLC By: Its Member Enclosure OPTION TO PURCHASE THIS OPTION TO PURCHASE AGREEMENT made and entered into this S day of 2015, by and between ROANOKE COUNTY, VIRGINIA, a political subdivision of the Commonwealth of Virginia, (hereafter, the "County"), and OLD SCHOOL PARTNERS, LLC, a Virginia limited liability company (hereafter, the "Company"). WITNESSETH: WHEREAS, the County is the owner of certain real estate situate in the Town of Vinton, Virginia, said real estate being the property described on Exhibit A attached hereto and made a part hereof; and WHEREAS, the Company desires to acquire an Option to Purchase said real estate upon certain terms and conditions all as herein contained; and WHEREAS, the County is willing to grant said Option upon the terms and conditions hereinafter set out. NOW, THEREFORE, in consideration of the mutual covenants and agreements contained herein, the parties agree and covenant as follows: 1. Grant of Option. In consideration of the sum of Five Hundred Dollars ($500.00), hereinafter referred to as the "Option Fee," paid by the Company to the County, receipt of which is hereby acknowledged, the County hereby grants unto the Company the sole and exclusive Option to Purchase the real estate situate in the Town of Vinton, Virginia, described on Exhibit A attached hereto and made a part hereof, hereinafter referred to as the "Property". Page 1 of 10 This "Option pee' is non-refundable, however in the event the option is exercised it will be applied to the purchase price of the property. 2. Term of Option. The term of this Option shall commence as of the date of this agreement and shall terminate and expire on December 31, 2015. The parties agree that, on or before said expiration date, the Company shall have the right to extend this Option for an additional period of six (6) months, through June 30, 2016, upon giving written Notice to the County and payment of the additional sum of $500.00, which shall be deemed an "Option Fee". 3. Notice of Exercise of Option. The exercise of this option to purchase the Property shall be made by Company giving written Notice of the exercise the Option to County on or before the expiration date of this Option. 4. Exercise of the Option. If the Company exercises the Option as hereinabove set forth, the parties shall perform their respective obligations as follows: (A) The purchase price for the Property shall be the sum of One Thousand ($1,000) which sum shall be paid by the Company to the County at settlement, subject to the payment of closing costs and the credits, including the Option Fee, and pro -rations set forth herein. (B) Settlement shall be made at the office of the Roanoke County Attorney, or at such other place as may be designated by the Company, sixty (60) days from the date of the notice of exercise of the Option, or as soon thereafter as the title can be examined, the necessary approvals can be obtained, and the settlement documents can be prepared, allowing a reasonable time to correct any objection reported by the title examiner. Page 2 of 10 (C) The County agrees that this agreement shall be subject to the Company receiving historic preservation certification Part 1 and Part 2 before title to the property is conveyed to the Company. (D) The County shall be responsible for preparation of the deed. The County shall be responsible for preparation of certificates required by Sections 1445 (FIRPTA) and 6045 (Form 1099-5) of the Internal Revenue Code, preparation of the Virginia Certificate of non - foreign status, payment of the tax imposed pursuant to the provisions of Section 58.1.802 of the Code of Virginia, 1950, as amended, payment of any other taxes properly payable by the County, payment of fees related to release of any note(s) or deed(s) of trust against the property, and payment of the County's attorney's fees, if applicable. Taxes, interest, and insurance escrow, if any, shall be prorated between the County and the Company as of the date of actual settlement. Except as otherwise specifically provided herein, all other costs and recordation fees incurred in connection herewith shall be the responsibility of the Company. (E) At settlement, County shall convey to Company good, marketable, and insurable fee simple title to the Property by Deed of Special Warranty free and clear of all hens, defects, and encumbrances, and subject only to such restrictions and easements as shall then be of record and which do not affect the use of the Property for the Company's purposes. If a defect is found which can be remedied by legal action within a reasonable time, County shall promptly take such action as is necessary to cure the defect. If the County, acting in good faith, is unable to have such defect corrected within sixty (60) days after Notice of such defect is given, and County elects not to expend additional sums for such correction, then Company may, at its option regardless of whether it has given notice of its exercise of the Option, either (i) Page 3of10 terminate this agreement, in which event the Company shall have no obligation to purchase the property, and this agreement shall be null and void, or (ii) waive the foregoing rights and enforce its rights to acquire the property as provided herein. The parties may extend the date for settlement by mutual agreement in order to comply with the requirements of this paragraph. (Ii) County shall deliver to Company at settlement an affidavit, signed by County, that no labor or materials have been furnished to the property within the statutory period for the filing of :mechanics' or materialmen's liens against the Property. If labor or materials have been furnished during the statutory period, County shall deliver to Company an affidavit signed by County and the persons) furnishing the labor or materials that the costs thereof have been paid. Such affidavit(s) shall be on form acceptable to Company's title insurance company, if applicable. (G) In the event that this option is exercised, Company agrees to participate in whatever contractual agreements are necessary to facilitate a like -kind exchange under Internal Revenue Code Section 1031 including, if necessary, amending this agreement so as to effect compliance with I.R.C. 1031 for such an exchange and to conform the terms of this agreement to accommodate the exchange, but not to alter the basic conditions of the agreement; provided, however, that such participation does not require the Company to acquire or take title to any real estate other than the property described herein. It is the intent of the parties to use a qualified intermediary or other mutually agreeable safe harbor under the 1031 Regulations to affect an exchange. Should the County exercise its rights under this section to use a 1031 tax deferred exchange, the Company shall make no representation or warranty as to Page 4 of 10 the legality or tax implications of such transaction. The County shall assume all liability incurred in connection with such transaction. (H) County agrees to exercise ordinary and reasonable care in the maintenance and upkeep of the Property, ordinary wear and tear excepted, from the date of this option agreement to the date of settlement. (I) All risk of loss or damage of any kind to the property shall remain on the County until the date of settlement. In the event of substantial loss or damage to the real estate or its improvements prior to settlement, Company shall have the option of either (i) terminating this Agreement and recovering the Option Fee(s), or (ii) affirming this Contract, in which event County shall assign to Company all of County's right under the policy or policies of insurance applicable to the property and pay over to Company any sums received as a result of such loss or damage. (j) Possession of the Property shall be given to Company at Settlement, except as otherwise provided herein or agreed in writing by the parties. 5. Environmental Study and Report. Company reserves the right to conduct its own environmental site assessment, and the County specifically agrees that Company's purchase of the Property shall be subject to and contingent upon receipt of satisfactory results from any environmental site assessments and audit reports which Company may, in its discretion and at its cost, deem appropriate, indicating to a reasonable degree of certainty that no Hazardous Wastes or Toxic Substances, as defined under federal, state and local environmental laws and regulations, are present upon the Property. In the event that an unsatisfactory report is received, Company may elect to terminate this agreement by providing Page 5of10 written notice to the County, regardless of whether the option has been exercised, in which event County shall return all Option Fees to the Company, this agreement shall become null and void, and neither party shall have any further rights or obligations in relation hereto. 6. Right of Access. During the period of this Option, the Company, and any of its agents or assigns, shall have the right to enter upon the Property for the purpose of conducting any and all desired or required surveys, tests, soil studies, soil borings, environmental tests or to perform any inspections or studies concerning the subject property. However, Company shall not unreasonably interfere with County's use of the Property, and shall endeavor to provide County and its agents advance notice of intended entries onto and activities upon the Property. In the exercise of privileges granted by this Paragraph, Company shall substantially restore the property to its original condition upon completion of such test or engineering work and shall be responsible for all loss, damage or expense directly arising from or attributable to Company's use of the property or entry thereon prior to settlement. 7. Real Estate Commission. The parties agree that no real estate agent or broker was utilized in this transaction and therefore no claim for a commission by a real estate agent or broker shall be paid by either party. 8. Special Conditions Contingencies and Covenants: This Option to Purchase Agreement is subject to and contingent upon all of the following: i. the Company will prepare a Historic Preservation Certification Application, Part 1 - Evaluation of Significance, and to prepare such other documents as may be necessary to seek the listing of the Property on the National Register of Historic Places; Page 6of10 ii. the Company will prepare a historic preservation certification application, Part 2 -- Description of Rehabilitation iii, the Company will work with the Town of Vinton to rezone the Property to allow for the proposed uses of this Project; iv. the Company agrees to provide County with the Additional Performance Security as security for Company's compliance with the terms and conditions of the Performance Agreement and completion of the Project in accordance with Company's Proposal and Plans. Company shall deliver to the County upon receipt of historic preservation certification and before commencing any renovation or construction work on the Property a letter of credit drawn against a bank or other financial institution qualified to, licensed, and conducting business in Roanoke, Virginia subject to prior approval by the County in County's sole discretion. The Additional Performance Security shall be payable to Seller and in the amount of $250,000 Dollars. 9. Assignment. This Option and all rights hereunder shall be freely assignable by the Company. if the Company shall assign the sane, all acts to be performed by it with respect to the purchase of the property including the execution and delivery of any and all documents, may be performed by any assignee whether the assignment is made before or after the exercise of this Option. Page 7 of 10 WITNESS the following signatures and seals: OLD SCHOO ARTjN'ERS, LLC By Cr (SEAL) BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA By (SEAL) Approved as to Form: q5A:Vq- r 11%J11iir,r+, Roanoke County Attorney's Of e .�`JSPN M. ''., NOTARY tate of Virg , - REG- #166141 = o ; MY COMMISSION of t -wit: EXPIRES 5/31/ e forego' ` h u ent was acknowledged before me this 3 E day of • 2015, by � i 5 CN[, for Old School Partners, LLC. &S &.,, M , 16 Notary Public Reg. # My Commission expires: State of Virginia, o J to -wit: The foregoing instrument was acknowledged before me this ,15%y of 2015, by Thomas C. Gates, County Administrator, on behalf of the Board of Supervisors of Roanoke County, Virginia, Company. Notary P11543 Reg. # �JnS B `i L1 My Commission expires: S /-3\ /.._201 S Page 9 of 10 AUDREY W PALMER Notary Public Commonwealth of Virginia 7098703 My Commission Expires Aug 31, 2015 10. Notice: All Notices and other correspondence regarding this option agreement shall be sent to the following addresses, unless otherwise designated in writing by the parties, by regular mail and by certified mail, return receipt requested, and the date of mailing shall be effective for purposes of determining timely notice. County: Thomas C. Gates, County Administrator County of Roanoke P. O. Box 29800 Roanoke, VA 24018 Company: Dale Wilkenson Old School Partners, LLC P. O. Box 450 Fincastle, VA 24090 11. Miscellaneous: (A) This agreement contains the entire understanding between the parties and may not be modified or amended except by written instrtunent executed by all parties. This agreement shall be construed, interpreted and applied according to the law of the Commonwealth of Virginia, and shall be binding upon and shall inure to the benefit of the parties and their respective heirs, personal representatives, successors, and assigns. (B) No waiver of any breach of covenants or conditions herein shall be construed as a waiver of a covenant or condition itself or any subsequent breach thereof. (C) The paragraph headings appearing in this Agreement are for reference purposes and shall not be considered a part of this Agreement or in any way to modify, amend, or affect the provisions hereof. (D) This Option is executed in duplicate, with each having the effect of an original, one of which shall be provided to each of the parties hereto. Page 8 of 11 EXHIBIT "A" Page 10 of 10 W ( O N2 W-'i— b� g"Iaro SN mzO�2 A� bba bA2 �C$ sxmY o a N 6 V v p O 4 0 � fp A y� [a x � G m b V b I W A �b b gba Q Q n O H n O�gi tiles y a� �S q b yqy 2 Y W ( O N2 W-'i— b� g"Iaro SN mzO�2 A� bba bA2 �C$ sxmY o a N 6 V v p O 4 0 � fp a Y [a x � G m b V b I W A '0 N p w tn q & tn >O> w oxw Lo o z K o N 46 \ . ow 0 0 v uK P P O a N V tl N SOUTH POPLAR STREET SOUTH BLAIR STREET (50, RA) e s o� awl Nei�s� Dl �NpKp3 { IS zAW h Rty Q H n y3� W tiles y 2 A q S SOUTH POPLAR STREET SOUTH BLAIR STREET (50, RA) e s o� awl Nei�s� Dl �NpKp3 { IS ACTION NO. ITEM NO. G.1-5 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: AGENDA ITEM: SUBMITTED BY: APPROVED BY: March 8, 2016 Appointments to Committees, Commissions and Boards Deborah C. Jacks Chief Deputy Clerk to the Board Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: 1. Board of Zoning Appeals (appointed by District) The Windsor Hills Magisterial District representative has passed away. Mr. Karr's five (5) -year term expires June 30, 2016. 2. Budget and Fiscal Affairs Committee (BFAC) (appointed by District and At -Large) The Budget and Fiscal Affairs Committee shall be comprised of eleven (11) members with each Board Supervisor having an appointment, five members appointed jointly by the Board of Supervisors, and one ex officio appointment representing County Administration. Mr. Gates is currently working with the Board on recommendations to this committee. 3. Clean Valley Council (At Large) Adam Cohen has resigned his appointment to the Clean Valley Counsel. His three- year term expired June 30, 2015. Page 1 of 2 4. Economic Development Authority (EDA) (appointed by District) The following four-year terms will expire on September 26, 2015: a) Greg Apostolou, representing the Hollins Magisterial District is eligible for reappointment 5. Parks, Recreation and Tourism Advisory Commission (appointed by District) Supervisor Al Bedrosian has recommended the appointment of David Linden to represent the Hollins Magisterial District. This is a three-year term and will expire June 30, 2019. Page 2 of 2 H AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION APPROVING AND CONCURRING IN CERTAIN ITEMS SET FORTH ON THE BOARD OF SUPERVISORS AGENDA FOR THIS DATE DESIGNATED AS ITEM H- CONSENT AGENDA BE IT RESOLVED by the Board of Supervisors of Roanoke County, Virginia, as follows: That the certain section of the agenda of the Board of Supervisors for March 8, 2016, designated as Item H - Consent Agenda be, and hereby is, approved and concurred in as to each item separately set forth in said section designated Items 1 through 7 inclusive, as follows: 1. Approval of Minutes — January 12, 2016 2. Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Charles Paitsel, Solid Waste Operations Supervisor, upon his retirement after more than forty-four (44) years of service 3. Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Diane L. Guerrant, Library Assistant, upon her retirement after more than twenty-seven (27) years of service 4. Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Penny K. Lloyd, Administrative and Marketing Manager, upon her retirement after eight (8) years of service 5. Resolution requesting acceptance of Paddington Station Lane, Queens Way and Stewart View Terrace into the Virginia Department of Transportation Secondary system 6. Confirmation of appointment to the Local Office on Aging (LOA) Advisory Council; Parks, Recreation and Tourism Committee (District) 7. Request for ratification of appointments of representatives to the Roanoke County Community Policy and Management Team (CPMT) Page 1 of 1 ACTION NO. ITEM NO. H-2 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Charles L. Paitsel, Solid Waste Supervisor, upon his retirement after more than forty- four (44) years of service SUBMITTED BY: Deborah C. Jacks Chief Deputy Clerk to the Board APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: Charles L. Paitsel, Solid Waste Supervisor, retired on January 28, 2016, after more than forty-four (44) years of service. Mr. Paitsel is unable to attend the meeting and his resolution and his quilt will be mailed to his home. STAFF RECOMMENDATION: Staff recommends adoption of the attached resolution. Page 1 of 1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION EXPRESSING THE APPRECIATION OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY TO CHARLES L. PAITSEL, SOLID WASTE SUPERVISOR, UPON HIS RETIREMENT AFTER MORE THAN FORTY-FOUR (44) YEARS OF SERVICE WHEREAS, Whereas, Charles L. Paitsel began employment with Roanoke County on August 11, 1971; and WHEREAS, Mr. Paitsel retired on January 28, 2016, after forty-four (44) years and five (5) months of devoted, faithful and expert service to Roanoke County; and WHEREAS, Mr. Paitsel, throughout his employment with Roanoke County, has been instrumental in improving the quality of life and providing services to the citizens of Roanoke County; and WHEREAS, Mr. Paitsel rose through the ranks of the Solid Waste Division becoming an expert in all levels of the division and ending his employment as the Solid Waste Supervisor responsible for twenty-eight (28) employees in the day-to-day operation of the division. WHEREAS, Mr. Paitsel was a major contributor in moving the division forward in the late 80's by coordinating the implementation of automated collection which involved new routing and new training for the solid waste equipment operators. Mr. Paitsel consistently provided leadership to the division and mentored new and seasoned employees in theirjob responsibilities. WHEREAS, Mr. Paitsel was a valuable asset to Roanoke County and helped the division achieve its goal of providing efficient and effective service to Roanoke County citizens on a daily basis through behind the scenes actions. Page 1 of 2 NOW THEREFORE, BE IT RESOLVED that the Board of Supervisors of Roanoke County expresses its deepest appreciation and that of the citizens of Roanoke County to Charles Paitsel for more than forty- four (44) years of capable, loyal and dedicated service to Roanoke County; and FURTHER, the Board of Supervisors does express its best wishes for a happy and productive retirement. Page 2 of 2 ACTION NO. ITEM NO. H-3 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Diane L. Guerrant, Library Assistant, upon her retirement after more than twenty-seven (27) years of service SUBMITTED BY: Deborah C. Jacks Chief Deputy Clerk to the Board APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: Diane L. Guerrant, Library Assistant, retired on January 1, 2016, after more than twenty- seven (27) years of service. Ms. Guerrant is unable to attend the meeting and her resolution and quilt will be mailed to her home. STAFF RECOMMENDATION: Staff recommends adoption of the attached resolution. Page 1 of 1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION EXPRESSING THE APPRECIATION OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY TO DIANE L. GUERRANT, LIBRARY ASSISTANT, UPON HER RETIREMENT AFTER MORE THAN TWENTY-SEVEN (27)YEARS OF SERVICE WHEREAS, Diane L. Guerrant was employed by Roanoke County on February 15, 1988 as a Library Page, and was later promoted to Library Assistant; and WHEREAS, during nearly three decades of service, Ms. Guerrant was an exemplary staff member who performed her duties quietly, competently, and collegially, freely sharing her knowledge and skills with patrons and colleagues; and WHEREAS, Ms. Guerrant participated in planning forthe renovation and expansion of the Hollins Branch Library in 1993 and worked with the rest of the staff to maintain full library services to the public throughout the long months of construction, during which the branch closed just one day; and WHEREAS, she demonstrated special acuity in challenges involving moving collections for optimal display and use by patrons; and WHEREAS, Ms. Guerrant willingly assumed responsibility for many support services that were vital to the successful operation of the Hollins Branch Library; and WHEREAS, Ms. Guerrant also contributed to the library system in general and was an important participant in resolving shelving placement, collection distribution, traffic flow issues, and other projects that resulted in the successful grand openings of new libraries at South County, Glenvar, and Vinton; and WHEREAS, Ms. Guerrant served as secretary to the Library Board of Trustees and was responsible for maintaining a true and faithful record of its actions and decisions until Page 1 of 2 her retirement; and WHEREAS, Ms. Guerrant retired on January 1, 2016, after twenty-seven (27) years and ten (10) months of devoted, faithful and expert service to Roanoke County; and WHEREAS, Ms. Guerrant, throughout her employment with Roanoke County, has been instrumental in improving the quality of life and providing services to the citizens of Roanoke County; and WHEREAS, NOW, THEREFORE, BE IT RESOLVED that the Board of Supervisors of Roanoke County expresses its deepest appreciation and the appreciation of the citizens of Roanoke County to DIANE L. GUERRANT for more than twenty-seven (27) years of capable, loyal and dedicated service to Roanoke County; and FURTHER, the Board of Supervisors does express its best wishes for a happy and productive retirement. Page 2 of 2 ACTION NO. ITEM NO. H-4 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Resolution expressing the appreciation of the Board of Supervisors of Roanoke County to Penny K. Lloyd, Administrative and Marketing Manager, upon her retirement after more than eight (8) years of service SUBMITTED BY: Deborah C. Jacks Chief Deputy Clerk to the Board APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: Penny K. Lloyd, Administrative and Marketing Manager with the Library, retired on January 1, 2016, after more than eight (8) years of service. Ms. Lloyd is unable to attend the meeting and her resolution and quilt will be mailed to her home. STAFF RECOMMENDATION: Staff recommends adoption of the attached resolution. Page 1 of 1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION EXPRESSING THE APPRECIATION OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY TO PENNY K. LLOYD, ADMINISTRATIVE AND MARKETING MANAGER, UPON HER RETIREMENT AFTER MORE THAN EIGHT (8) YEARS OF SERVICE WHEREAS, Ms. Lloyd began her association with Roanoke County as a member of the management staff of Virginia's Explore Park. She subsequently served as the Administrative and Marketing Manager in the County Administration from December 31, 2007, through June 30, 2008, after which she joined the Public Information Office, remaining there through December 24, 2010. She was asked to transfer to the Roanoke County Public Library on December 25, 2010, where she acted in the same capacity until her retirement on December 31, 2015; and, WHEREAS, Ms. Lloyd was first assigned by Roanoke County to design and coordinate numerous special events in Virginia marking the 75th Anniversary of the Blue Ridge Parkway. These celebratory programs were accomplished to considerable acclaim, enhancing public awareness of the history of the Parkway and appreciation for its ongoing role as a national park; and, WHEREAS, at the conclusion of that project, she served in the Public Information Office, creating new releases, project updates, and accurate and timely information on County activities to citizens, media, businesses, and local governments; and, WHEREAS, in 2010, Ms. Lloyd was asked to transfer to the Library to assist with the grand opening of the South County Library and its subsequent operations, and, WHEREAS, Ms. Lloyd, immediately brought a wealth of professional knowledge and sure expertise to her tasks, devising sound procedures and attractive promotional materials Page 1 of 2 for The Commons area of the Library, helping establish and maintain positive client relationships and an excellent reputation for the facility; and, WHEREAS, Ms. Lloyd coordinated numerous special events and grand openings for the Library, as well as the County, ensuring each was thoroughly planned, successfully accomplished, and memorable for both participants and attendees; and, WHEREAS, Ms. Lloyd also accepted many diverse assignments that helped improve Library service to the citizens, such as providing editorial oversight for in-house and Roanoke Valley Library Consortium marketing materials, or assembling a comprehensive manual of procedures and coordinating safety training for all staff; and, WHEREAS, Ms. Lloyd's thoughtful suggestions, keen insights, good humor, and quiet generosity made her a highly respected and greatly valued colleague; and, WHEREAS, throughout her employment with Roanoke County, she has been instrumental in improving the quality of life and providing services to the citizens of Roanoke County. NOW, THEREFORE, BE IT RESOLVED that the Board of Supervisors of Roanoke County expresses its deepest appreciation and the appreciation of the citizens of Roanoke County to PENNY K. LLOYD for eight (8) years of capable, loyal and dedicated service to Roanoke County; and FURTHER, the Board of Supervisors does express its best wishes for a happy and productive retirement. Page 2 of 2 ACTION NO. ITEM NO. H-5 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: AGENDA ITEM: SUBMITTED BY: APPROVED BY: March 8, 2016 Resolution requesting acceptance of Paddington Station Lane, Queens Way and Stewart View Terrace into the Virginia Department of Transportation Secondary system Tarek Moneir Deputy Director of Development Services Thomas Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: The County of Roanoke requests that the Board of Supervisors approve a resolution to the Virginia Department of Transportation (VDOT) requesting that they accept, as described by the AM -4.3: • 0.06 miles of Paddington Station Lane from the intersection of Route 1332 in the direction of North to the end of its cul-de-sac; • 0.05 miles of Paddington Station Lane from the intersection of 1332 in the direction of South to the end of its cul-de-sac; • 0.06 miles of Queens Way from the intersection of Route 1333 to the end of its cul- de-sac; • Stewart View Terrace from the intersection Route 1332 to the end of its cul-de-sac; and, • 0.02 miles of Queens Way from the intersection of Route 651 (Mountain View Rd.) to the intersection of Route 1333. Paddington Station Lane, Queens Way and Stewart View Terrace are located in the Vinton Magisterial District. See exhibit A for exact location. The staff has inspected these roads along with representatives of the Virginia Department of Transportation and finds the roads are acceptable. Page 1 of 2 FISCAL IMPACT: No County funding is required. STAFF RECOMMENDATION: Approve the attached resolution requesting VDOT to accept Paddington Station Lane, Queens Way and Stewart View Terrace into the Secondary Road System. ATTACHMENT: Exhibit "A"— Site location map Resolution VDOT Form AM -4.3 Page 2 of 2 oU�ta`�v`ew Rd. __ -- M s. -IIIIIIIIIIIII11d PROPOSED ADDITION(S) SHOWN IN BLUE Exhibit A NORTH DESCRIPTION LENGTH ROW WIDTH SERVICES As listed in the AM -4.3 Miles Feet Feet Houses 1. Paddington Station Lane; From: Int. of Rt. 1332, To: North to End, Cul-de-sac 0.06 50 28 14 2. Paddington Station Lane; From: Int. of Rt. 1332 To: South, End, Cul-de-sac 0.05 50 28 12 3. Queens Way; From: Int. of Rt. 1332 To: End, Cul-de-sac 0.06 50 30 4 4. Stewart View Terrace; From: Int. of Rt. 1333 To: End, Cul-de-sac 0.05 50 28 12 5. Queens Way; From: Int. Rt. 651 To: Int. Rt. 1333 0.02 50 30 0 ROANOKE COUNTY ACCEPTANCE OF PADDINGTON STATION LANE, QUEENS DEPARTMENT OF WAY AND STEWART VIEW TERRACE INTO THE VIRGINIA COMMUNITY DEVLOPMENT DEPARTMENT OF TRANSPORTATION SCONDARY SYSTEM AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION REQUESTING ACCEPTANCE OF PADDINGTON STATION LANE, QUEENS WAY AND STEWART VIEW TERRACE INTO THE VIRGINIA DEPARTMENT OF TRANSPORTATION SECONDARY SYSTEM WHEREAS, the streets described on the attached Addition Form AM -4.3, fully incorporated herein by reference, are shown on plats recorded in the Clerk's Office of the Circuit Court of Roanoke County; and WHEREAS, the representative for the Virginia Department of Transportation has advised this Board that the street(s) meet the requirements established by the Virginia Department of Transportation's Subdivision Street Requirements; and WHEREAS, the County and the Virginia Department of Transportation have entered into an agreement on March 9, 1999 for comprehensive stormwater detention which applies to this request for addition. NOW, THEREFORE, BE IT RESOLVED, this Board requests the Virginia Department of Transportation to add the street(s) described on the attached Additions Form AM -4.3 to the secondary system of state highways, pursuant to §33.2-705, Code of Virginia, and the Department's Subdivision Street Requirements, after receiving a copy of this resolution and all outstanding fees and documents required of the developer, whichever occurs last in time; and BE IT FURTHER RESOLVED, this Board guarantees a clear and unrestricted right-of-way, as described, and any necessary easements for cuts, fills and drainage; and Page 1 of 2 BE IT FURTHER RESOLVED, that a certified copy of this resolution be forwarded to the Residency Administrator for the Virginia Department of Transportation. Page 2 of 2 In the County of Roanoke ----------------------------------------------------------------------------------------------------------------- By resolution of the governing body adopted March 8, 2016 The following VDOT Form AM -4.3 is hereby attached and incorporated as part of the governing body's resolution for changes in the secondary system of state highways. A Copy Testee Signed (County Official).- Report fficial): Report of Changes in the Secondary System of State Highways Project/Subdivision Victoria Meadows Subdivision Type Change to the Secondary System of State Highways: Addition The following additions to the Secondary System of State Highways, pursuant to the statutory provision or provisions cited, are hereby requested; the right of way for which, including additional easements for cuts, fills and drainage, as required, is hereby guaranteed: Reason for Change: New subdivision street Pursuant to Code of Virginia Statute: §33.2-705 Street Name and/or Route Number ♦ Paddington Station Lane, State Route Number 1334 Old Route Number: 0 --—————————————————————————————————————————- • From: Int. Rt. 1332 To: North to End, Cul-de-sac, a distance of: 0.06 miles. Recordation Reference: Inst # 2006-08782 Right of Way width (feet) = 0 Street Name and/or Route Number ♦ Paddington Station Lane, State Route Number 1334 Old Route Number: 0 --—————————————————————————————————————————- • From: Int. Rt.1332 To: South, End, Cul-de-sac, a distance of: 0.05 miles. Recordation Reference: Inst # 2006-08782 Right of Way width (feet) = 0 Street Name and/or Route Number ♦ Queens Way, State Route Number 1332 Old Route Number: 0 --—————————————————————————————————————————- • From: Int. Rt. 1333 To: End, Cul-de-sac, a distance of: 0.06 miles. Recordation Reference: Inst # 2006-08782 Right of Way width (feet) = 0 VDOT Form AM -4.3 (4/20/2007) Maintenance Division Date of Resolution: March 8, 2016 Page 1 of 2 Street Name and/or Route Number ♦ Stewart View Terrace, State Route Number 1333 Old Route Number: 0 --—————————————————————————————————————————- • From: Int. Rt. 1332 To: End, Cul-de-sac, a distance of: 0.05 miles. Recordation Reference: Inst # 2006-08782 Right of Way width (feet) = 0 Street Name and/or Route Number ♦ Queens Way, State Route Number 1332 Old Route Number: 0 --—————————————————————————————————————————- • From: Int. Rt. 651 To: Int. Rt. 1333, a distance of: 0.02 miles. Recordation Reference: Inst # 2006-08782 Right of Way width (feet) = 0 VDOT Form AM -4.3 (4/20/2007) Maintenance Division Date of Resolution: Page 2 of 2 ACTION NO. ITEM NO. H-6 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY. VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Confirmation of appointments to the Local Office on Aging (LOA) Advisory Council; Parks, Recreation and Tourism Committee (District) SUBMITTED BY: Deborah C. Jacks Chief Deputy Clerk to the Board APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: Local Office on Aging (LOA) Susan Williams, Executive Director of the LOA has advised that Ron Keith Adkins is serving on their Board of Directors and is unable to serve on the LOA Advisory Council. They have appointed Gloria Clark to an additional one-year term to expire March 31, 2017. This appointment is made by the LOA, but must be ratified by the Roanoke County Board of Supervisors and accordingly has been placed on the Consent Agenda for approval. Parks, Recreation and Tourism Committee (District) Supervisor Al Bedrosian has recommended the appointment of David Linden to represent the Hollins Magisterial District to a three-year term to expire June 30, 2019. Accordingly, this appointment has been placed on the Consent Agenda for approval. Page 1 of 1 ACTION NO. ITEM NO. H-7 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: March 8, 2016 AGENDA ITEM: Request for ratification of appointments of representative to the Roanoke County Community Policy and Management Team (CPMT) SUBMITTED BY: Deborah C. Jacks Chief Deputy Clerk to the Board APPROVED BY: Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: In accordance with the Bylaws of the CPMT, all designees shall be ratified by the Board of Supervisors. The following appointments have been recommended by the Health Department and Court Services for the CPMT: • Suzanne Renegar — Health Department (primary) • Kimberly Lee — Court Service Unit (alternate) These appointments do not have an expiration date. STAFF RECOMMENDATION: Staff recommends the ratification of these appointments. Page 1 of 1 GENERAL FUND UNAPPROPRIATED BALANCE COUNTY OF ROANOKE, VIRGINIA Amount Audited balance at June 30, 2015 $ 21,799,195 Appropriated from 2015-2016 budget 506,153 J-1 % of General Fund Revenue 11.00% * Balance at March 8, 2016 $ 22,305,348 11.01 % ** Note: On December 21, 2004, the Board of Supervisors adopted a policy to increase the General Fund Unappropriated Balance incrementally over several years. * 2014-15 - Goal of 11 % of General Fund Revenues 2014-15 General Fund Revenues $198,174,499 11 % of General Fund Revenues $21,799,195 ** 2015-16 - Goal of 11 % of General Fund Revenues 2015-16 General Fund Revenues $202,656,326 11% of General Fund Revenues $22,292,196 The Unappropriated Fund Balance of the County is currently maintained at the goal of 11.00%. Submitted By Rebecca E. Owens Director of Finance Approved By Thomas C. Gates County Administrator W COUNTY OF ROANOKE, VIRGINIA CAPITAL RESERVES Minor County Capital Reserve (Projects not in the CIP, architectural/engineering services, and other one-time expenditures.) Amount Audited balance at June 30, 2015 $ 1,586,627 Appropriated for 2015-16 Capital budget (907,344) July 28, 2015 Appropriation to purchase voting machines and equipment (384,000) November 10, 2015 Allocation from expenditures for year end close out June 30, 2015 649,431 Balance at March 8, 2016 $ 944,714 Maior Countv Caaital Reserve (Projects in the CIP, debt payments to expedite projects identified in CIP, and land purchase opportunities.) Audited balance at June 30, 2015 $ 2,614,612 Appropriated for 2015-16 Capital budget (1,583,412) November 10, 2015 Allocation from revenues for year end close out June 30, 2015 $1,631,084 Balance at March 8, 2016 $ 2,662,284 Technoloav Caaital Reserve (Projects identified and prioritized by the Technology Governance Committee and approved by the County Administrator.) Audited balance at June 30, 2015 $ 314,058 Allocation to Computer Replacement Account (100,000) Balance at March 8, 2016 $ 214,058 Submitted By Rebecca E. Owens Director of Finance Approved By Thomas C. Gates County Administrator J-3 RESERVE FOR BOARD CONTINGENCY COUNTY OF ROANOKE, VIRGINIA Amount From 2015-2016 Original Budget $ 50,000 November 10, 2015 Appropriated funds to initiate the Intervenor process and develop strategy (15,000) Submitted By Approved By Balance at March 8, 2016 $ 35,000 Rebecca E. Owens Director of Finance Thomas C. Gates County Administrator IM COUNTY OF ROANOKE, VIRGINIA CHANGES IN OUTSTANDING DEBT Changes in outstanding debt for the fiscal year to date were as follows: Outstanding Outstanding June 30, 2015 Additions Deletions March 8, 2016 General Obligation Bonds $ 5,332,236 $ - $ - $ 5,332,236 VPSA School Bonds 104,311,123 7,761,248 96,549,875 State Literary Loans 1,825,775 - 1,825,775 - Lease Revenue Bonds 76,949,408 - 955,424 75,993,984 Capital Lease obligation 741,516 - 741,516 - $ 189,160, 058 $ - $ 11, 283, 963 - $ 177, 876, 095 Submitted By Rebecca E. Owens Director of Finance Approved By Thomas C. Gates County Administrator ACTION NO. ITEM NO. L-1 AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER MEETING DATE: AGENDA ITEM: SUBMITTED BY: APPROVED BY: March 8, 2016 Joint work session with the Roanoke County School Board to discuss various items Deborah C. Jacks Chief Deputy Clerk to the Board of Supervisors Thomas C. Gates County Administrator COUNTY ADMINISTRATOR'S COMMENTS: SUMMARY OF INFORMATION: This time has been set aside for a joint work session with the Roanoke County School Board. An agenda will be provided at the work session. Page 1 of 1 N AT A REGULAR MEETING OF THE BOARD OF SUPERVISORS OF ROANOKE COUNTY, VIRGINIA, HELD AT THE ROANOKE COUNTY ADMINISTRATION CENTER ON TUESDAY, MARCH 8, 2016 RESOLUTION CERTIFYING THE CLOSED MEETING WAS HELD IN CONFORMITY WITH THE CODE OF VIRGINIA WHEREAS, the Board of Supervisors of Roanoke County, Virginia has convened a closed meeting on this date pursuant to an affirmative recorded vote and in accordance with the provisions of The Virginia Freedom of Information Act; and WHEREAS, Section 2.2-3712 of the Code of Virginia requires a certification by the Board of Supervisors of Roanoke County, Virginia, that such closed meeting was conducted in conformity with Virginia law. NOW, THEREFORE, BE IT RESOLVED, that the Board of Supervisors of Roanoke County, Virginia, hereby certifies that, to the best of each member's knowledge: 1. Only public business matters lawfully exempted from open meeting requirements by Virginia law were discussed in the closed meeting which this certification resolution applies; and 2. Only such public business matters as were identified in the motion convening the closed meeting were heard, discussed or considered by the Board of Supervisors of Roanoke County, Virginia. Page 1 of 1