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HomeMy WebLinkAboutWPO200700069 Review Comments Stormwater Management Plan 2008-04-29ALg�,�� �'IRGINZ� COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 Project: WPO- 2007 - 00069, Jefferson Ridge Subdivision, Road, ESC & SWM Plan preparer: Mr. Eliot Fendig, PE, Bent Tree Design (fax 434.220.2533) Owner or rep.: Mr. Barry Meade, Southern Pines Investment LLC (fax unknown) Date received: 04 September 2007 (plan date 04 September 2007) 06 December 2007 (Rev 1) 22 Jan 2008 (Rev2) 25 Mar 2008 (Rev3) Date of Comment: 14 September 2007 20 December 2007 (Rev 1) 04 Mar 2008 (Rev2) 29 Apr 2008 (Rev3) Engineer: Jonathan Sharp A. Road Plans (WP0200700069) 1. VDOT approval is required before engineering can grant final approval. Revl: The latest VDOT comments are below (from 12118): • The guardrail detail needs to be shown for the GR -2 and GR -6. • The box culvert details BCD -DT and BCD -10 need to be shown. • Ditch #124 will need EC -2 lining to reduce the velocity within the ditch. • The sight distance triangles at the intersection of Briery West Drive and Jefferson Ridge Road need to be fixed. Rev2: A copy of the plans has been submitted to VDOT for review. Rev3: A copy of the plans has been submitted to VDOT for review. 2. All applicable state and federal agency approvals have not been received by Engineering. Revl: comments not addressed. Rev2: comments not addressed. Rev3: comments not addressed. 3. Please remove the proposed trees from the streets. Rev]: comments addressed. 4. Please label and define all street pavement radii. Rev]: comments addressed. 5. The sight distance easements will need to be platted and recorded before the final plat can be submitted for review. Revl: Any offsite sight distance easements required shall be platted and recorded prior to approval of the plans. Rev2: comments addressed. 6. Please show sight distances at the internal intersections. Rev]: comments addressed. 7. Please show all required street signage locations on the plans. Revl: The street name sign locations shall be located on the plans. Albemarle County Community Development Engineering Review Comments Sheet 2 of 5 Rev2: comments addressed. 8. PE -1 needs to be defined on the plan sheets. It appears this label could be removed from the entrance. The entrances will need to meet VDOT entrance requirements. Rev]: comments addressed. 9. Please revise the street ditch sections to meet VDOT standards. The riprap will need to be shown deeper than 6 ". Rev]: comments addressed. 10. All channel sections need to show each channel as it is designed for each drainage area. Rev]: Calculations are required for channel sections 3 -5. Please label the dimensions of channel sections 3 -5 on the channel profiles. Specify any necessary ditch linings on the plans. Rev2: comments addressed. 11. For the guardrails, show and label the required end sections on the plans. Rev]: comments addressed. 12. Show and label the end stations of the guardrails on the plan sheets. Rev]: comments addressed. 13. The detail for the guardrail is incorrect. Please revise accordingly. Ex. 5' is needed instead of 4'. Rev]: comments addressed. 14. Please revise the culvert #8 profile. It appears that the final grading will not work. Rev]: comments not addressed. Rev2: comments addressed. 15. Please show the 25 —yr storm headwater elevations. Headwater elevation needs to be 1.5' lower than the shoulder elevation. Show this information on all profiles. Rev]: Please verify that the 25 -yr storm does not overtop the roadway at culvert #7. Rev2: I cannot find the culvert calculations for the 25 -year storm for culvert #7. Rev3: comments addressed. 16. Please show the locations of the cross drains on the street profiles. Rev]: comments addressed. 17. The plans state that the topography is from three different sources. This causes problems on several plan sheets where the topography lines do not match. Label benchmarks used. Rev]: comments addressed. 18. Please show the drainage areas to Culverts on the plans. Rev]: comments addressed. 19. Please provide the dimensions of the proposed OP at each pipe outfall. Rev]: Specify the dimension of the proposed OP on the plan sheets and profile sheets. Rev2: comments addressed. 20. Please show all required grading for all drainage related items. Rev]: comments addressed. 21. Please confirm that all drainage items are within the easements. Rev]: Drainage easements from culvert or basin outlets shall extend to the property line. Rev2: Drainage easements are needed from culvert 5 and 6. Rev3: comments addressed. 22. Additional comments may be forthcoming on future plan submittals due to the required changes on the plans. 23. The road bond amount for this project has not been computed. Rev3: The ESC bond is computed at $1,143,720. Bonds cannot be posted until we have received VDOT, State, and Federal approvals, and a Bond Estimate Request and Schedule of Completion has been received. B. Erosion Control Plans (WP0200700069) 24. All applicable state and federal agency approvals have not been received by Engineering. Albemarle County Community Development Engineering Review Comments Sheet 3 of 5 Revl: comments not addressed. Rev2: comments not addressed. Rev3: comments not addressed. 25. Please clearly define the limits of disturbance. The entire 30,000 SF building area does not need to be cleared. Otherwise, please show grading and ESC measures for all disturbances. Rev]: On Sheet ESC -3, portions of sediment traps 22 & 24 are located outside the limits of disturbance. Rev2: comments addressed. 26. Please show the floodplain limits for all channels that exceed 50 acres. Revl: comments addressed. 27. Please put the correct project name on each ESC plan sheet. Rev]: comments addressed. 28. Please show locations for the soil stockpiles, tree burning areas, etc... Rev]: comments addressed. 29. Please show all required ESC labels on the plans. Rev]: comments addressed. 30. Please show how the second entrance to the State Route is protected. Rev]: comments addressed. 31. Please relocate SB 7 outside of the stream buffer. Rev]: Please relocate SB -7 outside of the 100 year storm elevation limits. Rev2: Please show the stream buffer, 100 year storm elevation limits, and floodplain limits clearly on all sheets of the E &S plans. Rev3: comments addressed. 32. The limits of disturbance go off the sheet on Sheet 4. Revl: comments addressed. 33. Please provide a written sequence of disturbance for the project. Rev]: comments addressed. 34. Please state in the ESC narrative the total amount of land disturbance. Rev]: comments addressed. 35. The ESC plan does not provide adequate perimeter controls for the proposed limits of disturbance as shown on the plans. Engineering recommends not showing the clearing of the lots. Rev]: comments not addressed. Adequate perimeter control has not been provided for all disturbance or phases of construction. Please provide adequate E &S measures during all phases of construction. Please utilize silt fence, diversions, additional traps, etc. Rev2: Perimeter control is still inadequate. Most use of silt fence is inadequate. Diversions need to be extended or provided to most downhill side sediment traps. As shown, sediment will not drain to the traps until the roadside ditches are in place. Examples of inadequate perimeter controls are as follows: • It appears that the majority of sediment traps placed below the roadway are undersized, based on post development drainage areas rather than pre development drainage areas. All erosion and sediment control measures are to be placed prior to or as the first step in clearing. • The DD arrows are going the wrong direction to ST -33. • A DD should be provided from 14 +00 on Bent Tree Drive to ST -27 at 38 +00 on Jefferson Ridge Road. • A DD should be provided from 32 +50 to 39 +00 on Jefferson Ridge Road to ST -18, as the site is unprotected from 32 +50 to 36 +00 on that side of Jefferson Ridge Road. • A DD should be provided around the cul -de -sac of Old Mill Ct to ST -25. • The DD pattern to ST34 is very awkward. It appears that a small basin can be Albemarle County Community Development Engineering Review Comments Sheet 4 of 5 constructed across the Swale on lot A]3. • SF uphill of ST -17 is inadequate. The SF running downhill will act as a DD. Please replace SF with DD from 44 +50 to 50 +00 on Jefferson Ridge Road and upsize ST -17 accordingly. • SF uphill of ST -11 is inadequate. The SF running downhill will act as a DD. Please replace SF with DD from 53 +50 on Jefferson Ridge Road to 14 +00 on Briery Creek Ct and upsize ST -11 accordingly. • SF around Briery West Drive is inadequate. It appears a DD and ST is needed. • The SF used from 53 +00 to 64 +00 along Jefferson Ridge Road is inadequate. A DD dike should be used. It appears ST -12 will need to be sized as a basin. • SF from 64 +00 to 69 +50 on Jefferson Ridge Road is inadequate. A DD and ST or basin is needed. • With the provided topo and drainage area map, it is difficult to tell whether or not all the runoff on the downhill side of the proposed road will make it to ST -12. • SF uphill of ST -15 is inadequate. The SF running downhill will act as a DD. Please replace SF with DD from 73 +00 to 82 +00 on Jefferson Ridge Road and upsize ST -15 accordingly. • The drainage area to ST -35 is incorrect. Rev3: comments addressed. 36. Please show stream bank stabilization instead of CIPs where the drainage area exceeds 3 acres. Rev]: comments not addressed. CIPs cannot be used for culverts with drainage areas in excess of 3 acres. Please remove the CIP label and show adequate channel stabilization. Rev2: comments addressed. 37. The bottom dimensions need to be defined for each sediment basin. Rev]: comments addressed. 38. The drainage area map needs to show and label the structures at each area. Rev]: comments addressed. 39. The E &SC plans need to provide start — end dates of the proposed construction? Rev]: comments addressed. 40. Additional comments may be forthcoming on future plan submittals due to the required changes on the plans. Revl: Outlet Protection is not shown on culvert #5, on sheet ESC -4. Rev2: Additional comments may be forthcoming on future plan submittals due to the required changes on the plans. 41. The ESC portion of the Water Protection Ordinance bond amount has not been computed. Rev3: The ESC bond is computed at $326,000. Bonds cannot be posted until we have received VDOT, State, and Federal approvals, and a Bond Estimate Request and Schedule of Completion has been received. C. Stormwater Management and Mitigation Plans (WP0200700069) 42. All applicable state and federal agency approvals have not been received by Engineering. Revl: comments not addressed. Rev2: comments not addressed. Rev3: comments not addressed. 43. The proposed SWM facilities do not meet state requirements. Please revise accordingly. Revl: No water quality calculations /removal rate calculations have been provided. Facilities shall be designed to treat as much of the roadway as possible. The Stormwater Management plans are incomplete. No further review can be done at this time. Rev2: Facilities shall be designed to treat as much of the roadway as possible. The Water Quality Albemarle County Community Development Engineering Review Comments Sheet 5 of 5 Table provided is very confusing. The Extended Detention Facility does not meet removal rate requirements. Several of the pre development drainage areas have a large percentage of impervious area. The site does not appear to have any pre development impervious area. Many of the drainage areas lists have removal rate requirements but then are listed as not needing facilites. Up to 37 biofilters are listed but 37 biofilters are not provided. It appears that additional BMP facilities are needed. Rev3: comments addressed. 44. Forebays will be required in the SWM facilities to meet the WQV requirements. Rev]: comments not addressed. Rev2: comments addressed. 45. Detention needs to be provided for the SWM facilities. These computations have not been provided with this application. Rev]: comments not addressed. Rev2: Detention computations are inadequate. Computations only take into account biofilter drainage areas, not the land development. For the areas not draining directly into the floodplain, please provide an analysis that shows that adequate detention per the County Code is met for the development. It appears drainage is channelized to three swales: a swale in lot Al, a swale in lot A5, and a swale between lots A6 and A9. Please show that detention requirements are met for these three drainage areas in order to protect downstream properties and receiving waterways from channel erosion and flooding. Please provide all required SWM calculations and information per the Engineering checklist found online. Rev3: comments addressed. 46. The mitigation plan sheet is incomplete. No comments can be provided with this submittal. Revl: comments addressed. Rev2: Please show the stream buffer, 100 year storm elevation limits, and floodplain limits clearly on all sheets of the SWM and Mitigation plans. Rev3: comments addressed. 47. Please show the grading for the SWM access roads to each facility. Rev]: Please show adequate access to all forebays /weirs /risers for all stormwater management facilities. Easements shall be provided for the access to the facilities. Rev2: Access requirements to all facilities are as follows (Engineering Checklist Page 9 of 12): vehicle access roads provided to all facilities access graded to 10' width and less than 20% grade minimum 10' wide permanent easement over access gravel surface or better for grades over 10% Rev3: comments addressed. 48. No further review comments can be performed on this submittal of the mitigation and SWM plans until the applicant meets the minimum requirements. 49. Additional comments may be forthcoming on future plan submittals due to the required changes on the plans. 50. The SWM portion of the Water Protection Ordinance bond amount has not been computed. Rev3: The SWM bond is computed at $528,000. Bonds cannot be posted until we have received VDOT, State, and Federal approvals, and a Bond Estimate Request and Schedule of Completion has been received.