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HomeMy WebLinkAboutSDP200800081 Review Comments Minor Amendment 2009-05-27� 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 E4 mia swm PBC JWTownsend.doc Project: J.W. Townsend Landscaping Improvements — Minor Amendment Plan preparer: Owner or rep.: Plan received date: Rev, l : Rev,2: Rev,3: Date of comments: Rev, l : Rev,2: Rev,3: Reviewer: Rev. l & 2: Rev. 3: [SDP200800081 ] Jim Taggart, TCS Engineering [fax 361 -1216] J.W. Townsend [email jay @townsendlandscape.com] 4 June 2008 25 August 2008 11 March 2009 5 May 2009 22 July 2008 09 October 2008 30 March. 2009 27 May 2009 Amy Pflaum, Current Development Review Engineer John Diez, Current Development Engineering Technician Phil Custer, Current Development Review Engineer Minor Site Plan Amendment Comments 5. A guardrail with VDOT designations (GR -2, GR -2a, etc.) is required next to parking or travelways adjacent to retaining walls or drop -offs of greater than 4 feet, with start and end sections labeled. [ 18- 32.7.2] (Rev. 1) Comment has not been addressed. (Rev. 2) Comment has not been addressed. Bumper blocks are needed on the parking spaces southeast of the relocated shed. Guardrails are required where there is a 2:1 slope. For example, adjacent to the southwest corner of the lower parking lot and adjacent to the travelway leading up to the lower parking lot. An alternative to guardrails is to provide 3:1 slopes adjacent to the parking or travelways. (Rev. 3) Comment has not been fully addressed. Bumper blocks and bollards have been added to the plan to address concerns at the higher elevation adjacent to the main building. But the main entry way stillpossesses side slopes steeper than 3:1. As graded, the slopes must be protected by a guardrail and planted with a low maintenance, non -grass groundcover. If the slope was graded at 3:1, both requirements would no longer apply and the comment would be addressed. Stormwater Management Plan Comments 15. Please address the stormwater management of the concentrated run -off from the proposed pond. Identify the adequate channel from this site. It appears a drainage easement may be needed from TMP 32 -22B 1. (Rev. 1) Comment has not been addressed. Concentrated run -off from the proposed pond has not been addressed. Concentrated run -off appears to be flowing to the neighboring property. Please identify the adequate channel from this site. Also, please provide a drainage easement from TMP 32 -22B1. (Rev. 2) Comment has not been addressed. Please provide an adequate channel analysis meeting Albemarle County Community Development Engineering Review Comments Page 2 of 2 all requirements from the County's Design Manual. (Rev. 3) The submitted channel analysis does not demonstrate to the county that the property downstream of the development contains an adequate channel. The n- values used for the calculations are too large and, therefore, underestimate the calculated velocities (the range specified in the green book is 0.025 - 0.223). In addition, due to the characteristics of the stream cross - section and the nature of the on -site soils as identified by the USDA soil survey, the permissible velocity of the existing eroded channel is likely 3fps or less. The applicant has 3 options to remedy this comment. 1) Make adjustments to the channel analysis by providing n -value calculations and permissible and computed velocities for each segment of each channel cross - section (the deeper, eroded portion of the channel cross - section will have faster velocities than the section above the banks). If the applicant chooses this option, there is a risk of still having to proceed to option 2 or 3 if the results of the calculations show an inadequate channel (the two year storm results in eroding velocities andlor the overflowing the channel banks). 2) Obtain permanent drainage easements to the culvert underneath Lewis and Clark Drive and upgrade the channel so that the 2 year velocities are non - erosive and the 10 year storm is contained within the banks of the channel. 3) Modify the facility so that the release rates for the 2 and 10 year storms are equal or less than a forested watershed of the same acreage (0.7cfs and 4.5cfs for the 2 and 10 year storms). To meet these release rates, the embankment and top of riser would need to be roughly 1ft taller and the 3in orifice would need to be lowered to around the 428 elevation. Please also provide graded access to the embankment of the facility and a trash rack on the 3in. orifice. On the 20 scale detail of the plan, please specify the pond plantings for the various zones of the facility (please see VSMH 3.05). 18. A Stormwater Management bond amount will be computed by the County once the WPO plans have been approved. A completed copy of the standard stormwater management maintenance agreement and fee for recordation for any stormwater management facilities will be required. [17- 304E] (Rev. 3) The SWM portion of the WPO bond has been computed to be $11,800. For questions regarding the posting of bonds, please contact Pam Shifflett and 296 -5832 x3246. 19. Please submit a completed copy of the standard Stormwater Maintenance Agreement and fee for recordation for the proposed stormwater management facilities. (Rev. 3) The agreement has been submitted and it is currently being processed. 29. (Rev.2) Please provide an updated Routing Report after the basin is modified. (Rev. 3) Comment has not been addressed. Please provide a full updated routing report. 30. (Rev. 2) Please remove the note regarding future stormwater management review. When a future site plan amendment is submitted, a stormwater management amendment will be required. Or, the applicant will be required to prove adequacy of the constructed facility. (Rev. 3) Comment has not been addressed. Please remove this note. Erosion & Sediment Control Plan Comments 31. An Erosion & Sediment Control bond amount will be computed by the County once the WPO plans have been approved. (Rev. 3) The ESC portion of the WPO bond has been computed to be $25,700. For questions regarding the posting of bonds, please contact Pam Shifflett and 296 -5832 x3246.