The URL can be used to link to this page

Home My WebLink AboutWPO202200005 Correspondence 2022-04-14SHIMP ENGINEERING, P.C. Design Focused Engineering April 14, 2022 David James County of Albemarle Community Development 401 McIntire Rd, North Wing Charlottesville, VA 22902 RE: Response Letter #1 for WP0202200005 Castalia Farm Winery Dear David, Thank you for your review of the VSMP plan for Castalia Farm — New Facility. This letter contains responses to comments dated March 8, 2022.Our responses are as follows: A. Stormwater Pollution Prevention Plan (SWPPP) 1. Submit the rest of the SWPPP for review. Registration Statement received. RESPONSE: The SWPPP has now been included. B. Pollution Prevention Plan (PPP) 1. Submit for review. RESPONSE: The PPP has now been included. C. Stormwater Management Plan (SWMP) 1. Include owner telephone & email contact information. [17-403] RESPONSE: Contact info is now provided. 2. Sheet C5, etc. — Bioretention #3 can be moved slightly to be outside of the buffer. RESPONSE: Bioretention basin 3 has been shifted outside of the buffer. 3. Sheet C8 — Show existing grade lines for each profile. RESPONSE: Existing grade is now shown on all profiles. 4. Det. Pond: Show number and spacing of barrel antiseep collars. RESPONSE: Antiseep collars are not necessary for this application based on the residence time of water in the detention pond. 5. Bioretention: (Ensure bioretention meets all requirements per DEQ specifications: https:Hswbmpvwrre.wp.prod.es. cloud.vt.edu/wp-content/uploads/2017/ 11 BMP-Spec-No- 9—BIORETENTION_v 1-9-0301201 1.pdf ) a. Ensure 2-ft minimum bottom to bedrock separation. b. Ensure 2-ft minimum bottom to seasonal high water table separation. c. Filter media: Please go with the 2011 standards on recommended bioretention soil mix composition (Table 9.6). We have found that higher % of fines (clay content) have caused issues with water filtrating though. 912 E. High Sr. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com d. Filter media: Ensure an infiltration rate of 2 in/hr (min). Test will be required prior to project termination. e. Show the underdrain (if used), cleanout and observation well locations on the plans and profiles. f. Provide sub -soil testing where underdrain is not used. g. Provide required surface area (sq.ft). h. Provide that the pretreatment SOD is approved as an acceptable form. RESPONSE: a. Soil testing will be performed prior to confirm bedrock separation. b. Soil testing will be performed to confirm high water table separation. c. A mix will be selected that more closely aligns with the 2011 standards that has a lower percentage of clay. d. All BMPs will be inspected for compliance with all appropriate specifications e. Sub -soil testing will be required so underdrain will not be used pending the results of the soil test. E Sub -soil testing will be provided at each bioretention basin. g. Required surface area is now shown in the bioretention basin design tables on sheet C 16. h. The pretreatment sod is included in the BMP design standards as an acceptable form. The BMP design table has been included on sheet C16 which allows for grass filter strips. 6. It appears that there is no concentrated runoff from the disturbed area to POA2 and Water Quantity requirements do not apply. You would only need to size the culvert for the upstream flow. Similar for culvert near entrance. RESPONSE: Agreed, the culverts have been sized based on the total upstream drainage area. 7. Include this checklist on the plan: https://www.albemarle.org/home/showpublisheddocument/3381/6373275105367000 00 RESPONSE: This checklist has been added. 8. SWM packet: Show hatching legend for land cover maps. RESPONSE: The land cover maps have been updated to include a legend. 9. Provide letter of availability from nutrient source provider. 0.91 TP credits currently required according to VRRM. RESPONSE: A letter of availability will be provided. We will contact Ana Kilmer to coordinate purchase prior to bond request. 10. Coordinated nutrient credit agreement with Ana akilmer@albemarle.org prior to purchase. Purchase of credits will be needed prior to bond request. RESPONSE: Acknowledged, we will coordinate with Ana for the purchase of nutrient credits. D. Mitigation Plan (MP) 1. Submit a mitigation plan for proposed disturbance in the stream buffers. RESPONSE: This has been included with the submittal on sheets C13 and C14. Since the existing area inside the stream buffers are wooded, only disturbed area will be used for planting seedlings. In order to meet the required planting area, other disturbed areas were selected that would benefit from new trees. 2. Provide culvert calcs and size them to pass the 25-yr storm. RESPONSE: Culvert calcs are now provided. Culverts are sized for the 25-yr storm. Please reference the hydrocad report. 3. For cro as of perennial streams, bridges, arch culverts, or box culverts shall be used. RESPONSE: Both streams are intermittent per USGS National Map and do not require arch/box 912 E. High St.. Charlottesville, VA 22902 1434.227.51401 shimp-engineering.rom culverts. 4. The stream crossing shall not disturb more than 30 1-11. It appears you exceed this amount at the second crossing. RESPONSE: The road has been adjusted to more directly cross the stream, limiting the total disturbance within the stream buffer. Disturbance may exceed 30' for fill slopes. 5. Add note to mitigation plan that stream bed and banks shall be stabilized within (7) days from start of backfilling and to notify inspector. RESPONSE: This has been included. 6. Provide copy of approved permit from USACE for the stream crossings. RESPONSE: This project falls under Nationwide Permit 18. 7. Show the design for a single stream crossing. Provide justification for two stream crossings. [ 17- 604 C][17-406 A.31 RESPONSE: Two stream crossings are required in order to access the tasting facility from Stony Point Pass and to connect the proposed production facility to the existing tasting room. The same stream is not crossed twice, but there are two stream branches between the tasting facility and new entrance. E. Erosion and Sediment Control Plan (ESCP) 1. Cover: Provide date(s) when site boundary and topography survey was performed. RESPONSE: Survey dates have been added. 2. Show VDOT entrance type. VDOT entrance permit will need to be obtained prior to permit issuance. RESPONSE: VDOT entrance type CG-I I has been added. 3. Sheet C 10/11— a. Show existing drainage divides. b. Show SC (VAESC HB, Spec. 3.24) for the stream crossings. c. Provide VSS, SSS (VAESC HB, Spec. 3.22, 3.23) as necessary. d. Tie-in proposed grading for traps. e. Show drainage area to diversions (5ac max). f. Ensure channel diversion directional change is not too severe & greater than 90 degrees. Energy dissipation check dams can be implemented. RESPONSE: a. Existing drainage divides are now shown for sediment traps in phase 1. Existing drainage divides for the entire site can be found in the predevelopment drainage area in the SWM calculation packet. b. Stream crossings are now identified. A temporary stream crossing detail has been added to the E&SC Details. c. VSS has been added as necessary. d. Proposed grading is now tied in to existing grade for sediment traps. e. The 5 ac. maximum only applies to diversion dikes (Spec. 3.09) and fill diversions (Spec. 3.10). Diversions will be used per Spec. 3.12 and are the only type of diversion with an area over 5 ac. L The severity of the directional changes of the diversions has been reduced to prevent erosion or spillover. 4. Sheet C 12, etc. - a. Conversion to permanent facilityBMP shall not occur until the road and all upstream drainage areas are fully stabilized. This would be after # 12 in the phase 2 sequence. b. Show SF here & provide B/M on slope: 912 E. High St.. Charlottesville, VA 22902 1434.227.51401 shlmp-engineenrig.rom RESPONSE: a. A third phase has been added to show upstream areas fully stabilized before transition to permanent SWM facilities. b. SF has been added around these areas and will remain during transition to permanent SWM facilities. 5. Sheet C 12 should still be showing ESC sediment traps and not the permanent SWM features in place. RESPONSE: A third E&SC phase has been added to show the transition from sediment traps to permanent SWM facilities. Sediment traps are now shown in Phase 1 and 2. 6. Provide the liner type requirement for the channel conveyances. RESPONSE: Liner types have been added for each channel. Please reference the ditch details on sheet C16 and the SWM calculation packet. If you have any questions or concerns about these revisions, please feel free to contact me at chris@shimp-en ing eering com or by phone at 434-227-5140. Regards, Chris Marshall, EIT Staff Engineer Shimp Engineering, P.C. 912 E. High St.. Charlottesville, VA 22902 1434.227.51401 shlmp-engineenrig.rom