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Home My WebLink AboutWPO202100069 Correspondence 2022-04-21 (2)SHIMP ENGINEERING, P.C. Design Focused Engineering April 21, 2022 John Anderson County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia 22902 RE: Response Letter #1 for WPO2021-00069 Scottsville Tiger Fuel Market - VSMP Dear John, Thank you for your review of the VSMP request for Scottsville Tiger Fuel Market. This letter contains responses to County comments dated 1/6/22. Our responses are as follows: A. Stormwater Pollution Prevention Plan (SWPPP) I. Please ensure SWPPP cover includes reference to WP02021-00069. RESPONSE: The WPO reference has been included. 2. Submit SWPPP using county template. a. Sec. 1: Registration Statement; please complete. Feel free to call if any questions. b. Sec. 6.A.: PPP Exhibit: Please show initial location of. i. Rain gauge. ii. Portable sanitary facilities (porta John), as required. iii. Covered non -hazardous waste dumpster, if required. iv. Vehicle wash waters, draining to trapping measure (Not a sediment trap design, per se, but shallow depression — 1-2 backhoe buckets. Avoid direct drainage to Ex. storm system, or pond/s.) v. Concrete wash -out. vi. On -site fuel, if required. vii. Paint, stucco, chemical storage, if required. c. Sec. 6E: List named individual responsible for PPP measures. d. Sec. 8: Although county personnel will inspect, Applicant is required to retain qualified (contractor/third-party) E&S inspection personnel to perform ESC inspections and evaluate compliance relative to VESCH, 3rd Edition, 1992. e. Sec. 9: Ensure Signed Certification is signed and dated. RESPONSE: A SWPPP with the required information above has now been provided. B. Pollution Prevention Plan (PPP) - see SWPPP item 2.b., above. The PPP content requirements can be found in County Code section 17-404. C. Stormwater Management Plan (SWMP) 1. Bioretention that receives `runoff from hotspot land uses should not be treated with infiltrating 912 E. High Sr. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com bioretention (i.e., constructed without an underdrain).' Ref. VA DEQ Stormwater Design Specification, p. 15 of 54, Hotspot Land Uses. Provide `an impermeable bottom liner and an underdrain system,' per DEQ design specification for hotspot land use. RESPONSE: An impermeable liner and underdrain system are now shown for the bioretention basin. 2. Show and label bioretention Level 1 pre-treatment on C6 profile. Ref. VA DEQ Spec. 9, Table RESPONSE: The pretreatment area has been labeled as Level 1 on the profile. 3. Include VA DEQ Specification No. 9 Table 9.6 Bioretention Material Specifications on the plan. RESPONSE: Table 9.6 from the bioretention basin spec is now included on C 13. 4. Include VA SWMH Inspection guidelines for bioretention on the plans —sent to Applicant as .PDF. RESPONSE: Inspection guidelines for bioretention basins are now included on sheet C 13. 5. Include VA DEQ Specification No. 9 Bioretention installation, maintenance, and periodic inspection measures on the plan, these items begin at p. 34 of DEQ Design Specification No. 9. https://swbmpvwrrc.wp.prod.es. cloud.vt.edu/wp-content/uploads/2017/ 11 BMP-Spec-No- 9 BIORETENTION v1-9_03012011.pdf RESPONSE: The maintenance and inspection measures from the bioretention basin spec are now included on sheet C 13. 6. Include Construction Record Drawings (As -built) for VSMP document on the plans, link: https://www.albemarle.org/home/showpublisheddocument/3381 /637327510536700000 RESPONSE: This has been included on sheet C 13. T C3 a. Show carwash wastewater discharge line in plan and profile, between carwash and sanitary collection (San. MH). b. Wherever storm runoff concentrates against curb, provide and label curb/gutter, CG- RESPONSE: a. The carwash wastewater discharge line is now shown in plan and profile. b. CG labels are now shown. 8. Provide letter of nutrient credit availability for proposed 0.96 lb. nutrient credit purchase. Nutrient credit purchase is not required for WPO plan approval, but is required to receive a Grading Permit. RESPONSE: A letter of availability has been included with this re -submittal. The nutrient credit has been updated so a new letter will be procured to reflect this change. 9. C6 a. Provide detention pond 22 LF emergency spillway detail (plan/profile). b. Provide bioretention planting plan, see VA DEQ Specification No. 9, Table 9.3. c. Label bioretention and detention pond critical elevations, for example: floor of each facility, stone layer INV, riser INV. If riser INV = 2.5" control orifice INV Elev. 396.00, please state this. d. Provide detention pond riser foundation detail; provide buoyancy calculations. e. Provide embankment Notes /design: cutoff trench, anti -seep collar details, etc., for detention pond. f. Label bioretention basin and detention pond side slope (3:1, for example). g. Request exception from Min. 3" orifice size, examine alternative designs that permit Min. 3" orifice size. RESPONSE: a. The emergency spillway is labeled in plan and shown in profile. b. A bioretention planting plan has been added per the bioretention basin spec. See planting list on sheet C13. c. All requested elevations are now provided. d. A riser foundation is now shown. Please reference the 912 E. High St.. Charlottesville, VA 22902 1434.227.51401 shimp-engineering.rom buoyancy calculations attached. The weight of concrete exceeds the buoyant force. e. Embankment details are now provided. A clay core and cutoff trench are shown for the pond and bioretention basin. f. Slope labels are now provided for both facilities. g. The design has been modified to allow for a 3" control orifice instead of 2.5". 10. Label detention pond outfall riprap dimensions, L x W x D. RESPONSE: Riprap dimensions are now labeled at the pond outfall. 11. Provide 36" riser low -flow orifice debris cage, and debris cage detail. RESPONSE: A trash rack and anti -vortex plate are now detailed for the standpipe with corresponding VDOT standard reference. 12. C1: Revise plan title to include ref- to WPO202100069. RESPONSE: The WPO # has been added to the plan. 13. Cale. packet a. Revise title pg. (letter d. 12/7/21) to include ref- to WP0202100069. b. Pg. 36 of packet /VaRRM.xls indicates 0.12 Ac. forest /open space post -developed land cover. Provide deeded easement for 0.12 Ac. (FOS easement), else revise VaRRMxls post -developed land cover table to reflect 0.0 Ac. forest /open space. A 1;Hst SWM approach, as needed, to r,.,._1 water quality compliance requirements at 9VAC25-8- RESPONSE: a. The WPO # is now shown on the calc packet title page. b. An open space easement will be provided in the plat for this development. 14. Provide SWM facility /Access easements via separate easement plat application. Link to application: httos://www.albemarle.ore/home/shomTublisheddocument/1052/637624089314100000 RESPONSE: A SWM facility/access easement will be provided and submitted in a new plat. 15. Provide and label SWM facility access. See requirements at ACDSM, p. 12, Best Management Practices for Stormwater Management. Provide mountable curb and other minimum features required for vehicular access to detention pond dam. RESPONSE: Facility access easements have been added. 16. Note: Easement plat must be recorded prior to WPO plan approval. RESPONSE: Acknowledged, the plat will be recorded prior to approval. 17. Note: SWM facilities are located on 1'MP 130A1-00-00-047B0; owner of TMP 130A1-00-00-047BO is a required party to SWM Facility Maintenance Agreement, and WPO plan bond. RESPONSE: Acknowledged, these parcels share the same property owner. D. Erosion and Sediment Control Plan (ESCP) 1. Provide labels that distinguish which is sediment trap 1, which is ST2, consistent with CI I ST tables. RESPONSE: Sediment trap labels are now shown that match the detail on C12. 2. ST1 adjacent to Valley Street, Rt. 20: Please increase trap size so that ST failure is less likely, and any failure is less severe. Roadside ditch -line topography may not readily accommodate release of sediment - laden water. Please target 25% increase above minimum required volumes. If design volume is the strict design minimum, then at- ire will be hard to remedy. It will be difficult to inc trap size, later. RESPONSE: Agreed, the sediment trap has been oversized to handle a 25% increase in capacity. 912 E. High St. Charlottesville, VA 22902 1434.227,5140 1 shimp-engineering.com ^'I le paved wash rack detail on plans; ref. p. 8, ACDSM, link: https://www.albemarle.org/Home/ShowDocurnent?id=270 RESPONSE: The construction entrance detail has been updated accordingly. Provide silt fence between diversion dike and Rt. 20_ RESPONSE: Silt fence is now shown between the diversion dike and Rt. 20. 5. C8: a. Label trap floor dimensions. b. Indicate stockpile location, if any. c. Area upslope of SF along southwest limits of disturbance exceeds 100 LF. Revise to provide additional or alternative VESCH measures, since upslope length above SF is 100' Max. d. Label drainage areas for each trap that correspond with Cl I DAs (1.36, 0.84 Ac.). RESPONSE: a. ST floor dimensions are now shown. b. Stockpiles are not anticipated for this site. c. The silt fence has been removed and the diversion dike extended to capture this area in sediment trap #2. The high point in the existing grade will be excavated to facilitate drainage until curb and drainage structures are installed. d. ST drainage areas are now shown on the phase 1 E&SC plan sheet. 6. Provide interim ESC plan and sequence that anticipate ESC measures required to transition ST2 to a detention pond while maintaining adequate ESC that prevents off -site sediment release. Ph ESC plan shows a perimeter sediment trap. Ph2 ESC shows biofilter, and a detention pond that occupies sediment trap (ST2) location without any indication how site runoff will be controlled as site transitions from Pal to Ph2. During transition, site runoff must be controlled with adequate ESC measures at south edge of site. RESPONSE: Additional SF is now shown being placed prior to conversion of the sediment trap to the detention pond. 7. Provide Note that biorctcntion may not he constructed until all upslope areas arc stabilized. RESPONSE: A note has been added that the upslope area must be stabilized prior to bioretention basin construction. 8. Provide SAF along Rt. 20 and Rt. 726. RESPONSE: SF is now shown along Rt. 20 and 726. 9. if unbalanced cut/fill site, if export is required, please note destination for off -site export. RESPONSE: No offsite disposal is anticipated. Should that change, the registration statement and permit will be updated. If you have any questions or concerns about these revisions, please feel free to contact me at chris@shimp-engineering.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 1434.227,5140 1 shimp-engineering.com