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Home My WebLink AboutWPO202000017 Correspondence 2021-06-07SHIMP ENGINEERING, P.C. Design Focused Engineering June 7, 2021 David James County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902 RE: Response Letter #4 for WPO202000017 — Proffrt Road Townhomes South Dear David, Thank you for your review of the VSMP request for Proffit Road Townhomes South. This letter contains responses to County comments dated May 5, 2021 Our responses are as follows: B. Stormwater Pollution Prevention Plan: 3. Update SWPPP with any changes. SWPPP has been updated with this revision. C. Pollution Prevention Plan 1. Please include offsite area on the PPP. Also, add a Staging area & symbol. (Rev.2) Update sheet with any changes to the plan. PPP has been updated with this revision. D. Stormwater Management Plan 6. Please route the storm pipes & structures around the embankment and biofilter so construction will not disturb the BMP. Comment resolved per phone conversation on 05/05/2021. 7. See D.20. below and revise weir plate detail. Comment resolved per phone conversation with Frank V. Phol, David James and Justin Skimp. 16. Record the SWM maintenance agreement prior to approval. [Sec. 17-415] (Rev.1/2) Comment still applies. Acknowledged. The SWM maintenance agreement has been submitted on May 28" 2021. 17. A recorded SWM facility easement plat & deed prior to permit issuance. (Rev.1) Comment still applies. (Rev.2) Acknowledged. Please submit the road plan for review. See E.3. Road Plan will be submitted. 18. Provide letter of availability from the off -site nutrient bank provider. Currently 1.16 TP load credits required. [Sec. 17-403 A.9] (Rev.1) Acknowledged. Currently 1.37 credits needed. (Rev.2) Purchase required prior to plan approval. Please work with Ana on Nutrient credit agreement. Comment resolved. The availability letter provided on March 312021 is correct. The owner is working with Ana regarding the nutrient credit purchase. 20. (Rev.1) Sheet 9 (Weir plate detail) — Orifices under 3" are susceptible to clogging & increase maintenance. Increase diameter, provide anti -clogging device/feature. (Rev.2) County requires 3" min. orifice. Please provide what the design discharges (1-,2- ,10-yr) would be for a 3" orifice. A waiver request & fee will need to be submitted. Comment resolved per phone conversation with Frank V. Phol, David James and Justin Skimp. SHIMP ENGINEERING, P.C. Design Focused Engineering 21. (Rev.2) Please show the VRRM on the plans. VRRM Maps are included on the Plan with this submission. Please see Sheet C13 & Sheet C14. 22. (Rev.2) The point of analysis needs to be at the discharge from the end of the newly installed riprap outfall. a. Ensure Flood Protection is met (9VAC25-870-66 C). i. Provide flooding analysis (10-yr) to confirm the pre -development flows at that point. Comment resolved per phone conversation with Frank V. Phol, David James and Justin Shimp. ii. Provide flooding analysis (10-yr) to confirm the post -development flows at that point. Comment resolved per phone conversation with Frank V. Phol, David James and Justin Shimp. E. Stormwater Manasement Plan 3. Provide offsite easement for proposed drainage connection to offsite SWM facility. A letter from off -site property owner is enough for this plan review, but any legal easements will need to be signed by the property owners. [ACDSM, p.22] (Rev.1) Partially addressed. You can also record an easement plat. (Rev.2) Acknowledged; submit the plat for review or provide letter. The offsite easement will need to be recorded prior to permit issuance. The offsite easement has been recorded. A copy is Attached with this submittal. Permeant Stormwater Easement will be recorded with the Subdivision Plat. 5. Sheet 6 — C. (Rev.2) Install SF all along perimeter of offsite disturbance. Silt has been added as requested. 6. (Rev.2) Sheet 5/6 — Install DD & SF perimeter controls. Silt fence and Diversion Dike have been added as requested. Other Revisions with this submittal: 1. Per phone conversation with Frank V. Phol, David James and Justin Shimp, with this submittal the Stormtech Chambers row where Structure A6 is located has been converted to be Isolator row to treat the site area on the west side. 2. Structure A4 so that it has two points of access. This will allow easier access inside this structure because the weir plate is inside this structure. If you have any questions or concerns about these revisions, please feel free to contact me at steohanie@shimp-en ing eering com or by phone at 434-227-5140. Regards, Stephanie Paul Shimp Engineering, P.C.