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HomeMy WebLinkAboutWPO200800014 Review Comments Erosion Control Plan 2008-06-20� OF AL ,. vIRGI1`IZP COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 Project: Old Trail Village Block 3 -Phase A [SDP200800035, WPO200800014] Plan preparer: Collins Engineering fax 245 -0300 Owner or rep.: March Mountain Properties, LLC fax 245 -0300 Plan received date: 22 February 2008 REV 1: 24 April 2008 REV 2: 18 June 2008 Date of comments: 7 April 2008 REV 1: 6 June 2008 REV 2: 18 June 2008 Reviewer: Phil Custer REV 1: Amy Pflaum REV 2: 18 June 2008 The Final Site Plan for Old Trail Block 3 has been reviewed. Current Development Engineer staff will recommend approval of this plan once the following comments have been addressed. A. Final Site Plan [SDP- 2008 - 00035] 1. On all slopes steeper than 3:1, please specify a low- maintenance groundcover. [DM] REV 1: Sod is not an acceptable Low Maintenance Ground Cover. Please revise the note on Sheet S2 to read "...LOW MAINTENANCE GROUND COVER, NON - GRASSED." Also, please remove the following note at the top of Sheet S -2: 1. ALL PROPOSED AREAS WITH SLOPES GREATER THAN 3:1 SLOPE SHALL BE SODDED TO PREVENT EROSION. REV 2: Comment addressed. 2. The sidewalk adjacent to the entrance to the pool parking lot from Marlbeck measures to be 4.5ft. REV 1: Comment addressed, sidewalk is now shown as 5 ft.. 3. The entrances off of Claremont appear to have been reduced from 20ft to 16ft. Please note that this acceptable for alleys, but if a parking lot is designed in Phase B, a 20ft minimum width is required. REV 1: Comment noted and entrance removed from plan. 4. Please note on the title sheet that this plan amends the downstream drainage of the approved Block 1 site plan (SDP- 2007 - 00144). REV 1: Comment addressed, note added to Title Sheet. 5. Please move street trees into the planting strip inside the ROW. REV 1: Comment addressed, trees inside planting strip. 6. Please show street trees on both sides of the proposed roads. Street trees should be shown on the plan for entire length of the roadway, not just around the Phase A portion of the block. REV 1: Comment addressed, street trees shown on both sides of road. 7. All curb inlet spreads for a storm of 4in/hr intensity must be below 1Oft. REV 1: The spread for inlet STR -27 continues to be 10.57 ft, however, this is deemed acceptable because the curb to crown width is 11 ft, therefore, no overtopping is expected to occur. Albemarle County Community Development Engineering Review Comments Page 2 of 3 B. Stormwater Management Plan [WPO- 2008 - 00014] 8. The Lickinghole SWM basin pro -rata fee will be computed once the site plan has been approved. REV 1: Comment noted. C. Site Erosion and Sediment Control Plan [WPO- 2008 - 00014] 9. Please submit a fee of $130 for the erosion and sediment control amendment to the Block 3 mass grading plan. REV 1: Fee submitted 4/24/08. 10. This ESC plan does not appear to match the mass grading plan submitted at approximately the same time: facilities are located in the buffer; traps are shown where basins should be due to the size of the watershed; etc. The two plans should show the same information for the initial phases of the ESC plan. Please refer to my comment letter for the first submittal of the mass grading plan for comments regarding ESC Phase 1 of the Phase 6 -Block 3 Phase A plan. REV 1: Comment noted, new mass grading plan to match shall be submitted. 11. The existing SWM pond cannot be used as a sediment basin. Please provide an alternative design for this area. (See comment below). Also, please remove all references to the existing SWM pond to be used as a sediment basin. REV 1: Comment addressed, existing SWM pond is no longer being utilized as a sediment basin. 12. Engineering review is concerned that sediment -laden water will enter into the existing SWM pond after passing through the inlet protection provided on the plan. Engineering review recommends installing a temporary pipe from structure 6 and outfalling into a sediment basin sized for the entire storm sewer watershed (-17 acres). REV 1: Block 1 will not drain to this basin, it will continue to drain through an existing temporary pipe to the basin located behind Block 1. A temporary pipe is proposed from STR 6 to the sediment basin so that sediment laden flow will not reach the existing SWM pond. Please add information about this temporary pipe (size, slope, outlet protection) to the plans. It appears that the temporary pipe may be conflicting with the location of a proposed sanitary sewer manhole. If the 42" pipe connecting STR 6 to the pond is to be constructed with this site plan, please show it on Sheet E -3 and indicate that its inlet within STR 6 will be plugged until such time as the temporary pipe is removed. REV 2: Comment addressed. 13. Limits of disturbance lines cannot encroach on the "Conservation/Preservation Areas" (shown in Sheet 3 of 9) without amending the rezoning plan. The pond also has a 100ft buffer from its water level that no filling operation can take place in. However, temporary ESC or permanent SWM measures will be allowed within the buffer as long as the disturbance is outside the "Conservation/Preservation Areas" as shown on the ZMA plan. REV 1: Comment addressed. 14. What is the symbol SSF? There is no mention of it in any of the sheets. If the intention of the applicant is to provide "super silt fence" (a chain - linked fence reinforced silt fence), please note that the use of this method is not listed in the VESCH and requires a variance from the program authority. If you wish to leave this method in the plan set, please provide a letter requesting a variance of the standard to Mr. Glenn Brooks. A detail of the method's installation specifications would also be helpful. (Please also note that the wire reinforced fencing, as shown in the VESCH, still receives the call -out "SF ".) REV 1: Comment addressed, silt fence noted as SF. 15. It appears that the connection from MH -2 to the sanitary sewer main could be made out of the stream buffer if the connection point was closer to MH -7. Disturbance of the stream buffer for public utilities is not exempt if lines could be practically relocated to outside of the stream buffer. [17- 319.B.1] Albemarle County Community Development Engineering Review Comments Page 3 of 3 REV 1: Comment addressed, one proposed manhole has been moved out of the buffer and disturbance has been minimized. 16. A bond amount will be computed by the County when the plans have been approved. REV 1: Comment noted. 17. REV 1: Is there an adequate channel to convey flow from Sediment Basin 2 to the stream? REV 2: Comment addressed. D. Road Plan [SDP- 2008 - 00035] 18. VDOT approval is required. Comments will be forwarded to the applicant once comments have been received. REV 1: Comment noted. 19. The ROW of Claremont Lane measures to be 5311, not 5411. The planting strip measures to be 3ft rather than 4ft as shown in the roadway section. REV 1: Comment addressed, Claremont Lane is not shown with a 55' ROW and 6ft planting strips. 20. The minimum planting strip allowed is 6ft. This is a requirement in both the County Code and the Old Trail Code of Development. The horizontal placement of the sidewalks, planting strips, ROW line, and curbing was satisfactory in the second submittal of the preliminary plan. The applicant has since reduced the section. Please see comment #3 from my letter sent 22 January 2008. [14- 422] REV 1: Comment addressed, planting strips are shown as 6ft. 21. Please show all necessary cross drains on the road profiles. REV 1: Comment addressed. E. Mass Grading Plan [WPO- 2008 - 00014] 22. The dewatering orifices are not sized to the specifications in the Virginia Erosion and Sediment Control Handbook. REV 1: Using the equation in the VESCH, for a 6 -hour drawdown time, engineering staff is calculating smaller orifice sizes for the sediment basins than you have shown. REV 2: Comment addressed. 23. Please provide a baffle for the eastern diversion dike into Sediment Basin 1. REV 1: A baffle has been provided in Sediment Basin 1, however, it will not intercept the flow from the eastern diversion dike, please revise the location of the baffle. REV 2: Comment addressed.