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HomeMy WebLinkAboutWPO202000007 Correspondence 2021-04-06 (3)608 Preston Avenue P 434.295.5624 Suite 200 IF434.295.1800 T I M M O N S GROUP Charlottesville, VA 22903 www.timmons.com April 6, 2021 John Anderson County of Albemarle Dept. of Community Development 401 McIntire Rd, Rm 227 Charlottesville, VA 22902 RE: Hark Vineyards Tasting Room - VSMP Plan Review - WP02020-00007 - Comment Response Letter Dear Mr. Anderson: We have reviewed all of your comments from (Rev. 1) February 22, 2021 and made the necessary revisions. Please find our responses to the comments below in bold lettering. A. Stormwater Pollution Prevention Plan (SWPPP) The SWPPP content requirements can be found in County Code section 1 7-405. A SWPPP must contain (1) a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL measures necessary. 1. Sec. 1, Registration Statement is incomplete. Complete Sec. 1 as condition of VSMP / WPO plan approval. a. Sec. I.A. Operator/ Perm ittee information: Section is blank; please complete. (Rev. 1) Not addressed. Section has been checked and is completed. b. SeE. W.B./Estimated p Et dates: Complete c. fog W C/Commo—n DIa., of Development: please Eheck yes. Review error; withdrawn. d. Sec. VI/Certification: Please complete. (Rev. 1) Not addressed. ENGINEERING I DESIGN I TECHNOLOGY Section will be completed once a contractor selection has been finalized. e. New: Sec. II.B., C., E., G.1 - Complete all sections of Registration Statement. Please QC Sections were completed on previous submittal. 2. Sec. 4, 5: Update these sections with revised ESC and SWM plan sheets, once comments are addressed. (Rev. 1) Persists. Section have been revised with updated plans. 3. Sec. 6.A / Exhibit: Indicate location rain gauge. (Rev. 1) Addressed. As follow-up: a. Provide silt fence downslope of stockpile. Silt fence has been provided around stockpile. b. Provide depression / small trap to collect vehicle wash waters (not VESCH design /small). A depression has been called out to collect vehicle wash waters. c. Provide catchment / small trap to intercept runoff from dumpster, mortar mix, temp. toilets. These items are shown on ungraded slopes with no downslope catchment, or barrier to overland flow. Dumpster, mortar mixing station, and temporary toilets have been relocated and are now uphill of a depression / catchment for runoff. 4. Sec. 6.E. - List named individual responsible for pollution prevention practices prior to VPDES permit registration. (Rev. 1) Persists. List named individual prior to VAR10 CGP Registration for state permit. This section will be completed once a contractor has been selected. 5. Sec. 8. - List named individual qualified to perform compliance inspections prior to VPDES permit registration. (Rev. 1) Persists. List named individual prior to VAR10 CGP Registration for state permit. Section will be completed prior to registration permit once a contractor and subs have been finalized. 6. Sec. 9., Signed Certification: Individual who prepared SWPPP document must sign as condition of VSMP / WPO plan approval. Albemarle cannot register project with DEQ until SWPPP Sec. 9 is complete. (Rev. 1) Persists. Section will be completed once a contractor has been selected. 7. Sec. 11 - Include copy of 26-p 201 9VAR10 VPDES General Construction Permit. (Rev. 1) Addressed. 8. Sec. 12 - Include template inspection forms. (Rev. 1) Addressed. 9. Include 2019 Notice of Termination form. (Rev. 1) Not Addressed. Notice of termination has been included with SWPPP. See section 13 10. Revise SWPPP title to include ref. to VSMP / WPO2020-00007. (Rev. 1) Addressed. B. Pollution Prevention Plan (PPP) - See above. Limited follow-up items. The PPP content requirements can be found in County Code section 1 7-404. C. Stormwater Management Plan (SWMP) VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This plan is disapproved for reasons listed below. The stormwater management plan content requirements can be found in County Code Section 17-403. 1. A SWM Facility Easement Plat is required for this project. (Rev. 1) Withdrawn. Initial comment is revised to require stormwater management maintenance agreement, Sec. 1 7-41 5, which ensures county access for periodic inspection/maintenance, and stipulates owner obligation to maintain SWM facilities. Platted easement is not, however, required. Platted easement with deed is required for: subdivision developments [14-428]; site plan developments [1 8-32.7.4.2]; and if a forest -open space (FOS) area/acreage value is entered as post -developed land cover in VRRM.xls [DEQ Guidance Memo No. 16-2001 , May 2, 2016]. Chapter 17 alone does not stipulate easement requirements for SWM facilities. Ch. 14 and 18, however, do. This site does not require a site plan and does not propose subdivision or FOS Easement; therefore, platted easement and SWM facility deed are not required. A SWM Facility Maintenance Agreement and surety/bond for SWM facilities are required. A SWM easement is now shown on plan sheet C5.0. We will begin coordination with Ana Kilmer for a SWM Facility Maintenance Agreement and surety/bond for the SWM facilities. C0.0: 2. Revise title to include VSMP / WPO2020-00007. (Rev. 1) Addressed. 3. Revise Note 2. Shift install detention piping to sequence step 8., or revise notes to ensure detention system remains off-line until upslope areas are stabilized. (Rev. 1) NA - Design revised. 4. Source of topography is given as county GIS. Provide source of survey basis of design (SWM facility / storm pipe design elevations). (Rev. 1) Addressed. 5. Revise drawing index, C-1 .3 to ref. Site Layout. A VSMP/WPO plan cannot include/approve a site plan. (Rev. 1) Addressed. C2.0: 6. Identify and provide ownership data for adjacent parcels (TMP #, Owner name, deed bk. -pg.). (Rev. 1) Partially Addressed. As follow-up: Provide large scale image that depicts entire development parcel, with every adjacent TMP identified (TMP#, owner, deed bk. -pg.). Also: list intersecting road distance SE / NW. An Adjacent Property Exhibit has been provided to display the required information above. See plan sheet C0.1. 7. Recommend coordinate entrance location with VDOT. Acquire VDOT permits, as needed. (Rev. 1) Persists. Entrance is shown on C3.4. Comment Acknowledged. VDOT coordination is underway. 8. Label critical slopes. (Rev. 1) Withdrawn. No critical slopes in vicinity of development (lot/building). C4.0: 9. Revise sheet title to site layout. (Rev. 1) Addressed. 10. Recommend label typical parking space dimensions. (Rev. 1) Addressed. 11. Show yard drain outfall (Show connection to SWM system, or release point). (Rev. 1) NA - Design revised. 12. Provide 50' gas pipeline easement bk.-pg. reference. (Rev. 1) Addressed. 13. Provide note listing depth (or suspected depth) to gas pipeline. (Rev. 1) Withdrawn. 14. Provide precautionary Note to contractor concerning grading within gas pipeline easement. (Rev. 1). Persists - Provide Note on C5.0. A precautionary note has been added to sheet C2.0 and C5.0. 15. Provide retaining wall details; for example: type, length, Max. height. (Rev. 1) NA - Design revised. A retaining wall 0 5' high; C4.0, C5.0) is incorporated into building design to be reviewed as part of building permit application review / approval process. Acknowledged. 16. Provide SWIM facility description (material, slope, overall L x W x DIA x # lines). (Rev. 1) NA - Design Revised. 17. Recommend label post -developed improvements, i.e.: asphalt parking, concrete walk, etc. (Rev. 1) Addressed. 18. Label two culverts near vineyard entrance. (Rev. 1) NA - Design revised. 19. Recommend show site water supply (well). (Rev. 1). Addressed. C-1.3: 20. VaRRm.xls land cover summary post -development lists Final Post Dev Site Rv — 0.53; revise Energy balance equation to use this post-dev Rv. (Rev. 1) NA - Design revised. 21. Ensure energy balance equation indicates compliance. (Rev. 1) Persists. Also, item 50., below. Stormwater design has been revised to comply with Energy Balance for the disturbed areas that will be concentrated in the post condition. 22. Provide Q(1) un-detained calculations, since methodology unclear. 14.31 cfs does not match C-1.9 hydrographs. Label un-detained drainage divide in image. 'Overall drainage areas.' Align graphic, routings, calculations, energy balance, and compliance narrative with aim toward simplicity, and clarity. C-1 .3 and C-1 .9 provide a partial, somewhat confusing analysis of drainage and SWM compliance data. (Rev. 1) Design revised. 23. Revise using I.F. — 0.8. Engineering check, energy balance: Qpost — (0.8)(14.50)(0.20)/0.53 - Qpost undetained. (Rev. 1) Persists - Although design revised, this comment is relevant. Water quantity compliance requires energy balance since proposed discharge is to a natural conveyance (ref. review item 50., below). Note: Simply altering location of outfall does not address comment. Given slopes across site, ELS is a non- viable stand-alone concentrated -to -sheet flow transition device. Runoff must be detained (reduced) on this site. Stormwater management for the site has been revised to include detention of the impervious concentrated areas in the post condition. See sheet C7.0 for revised flood and channel protection. 24. Provide post -developed impervious cover table, listing impervious area (sf) of: (Rev. 1) Persists. a. Drive b. Walks c. Parking d. Buildings i • Q'- H. QI�z III. —Eta Impervious cover table has been provided under the Water Quality Calculations on plan sheet C7.0. 25. Show existing structures (structures visible in GIS). (Rev. 1) Addressed. 26. Label terrain contours; provide elevation labels. (Rev. 1) Addressed. 27. Label roads beyond property boundary. (Rev. 1) Addressed. 28. If nutrient credit purchase proposed, coordinate with Ana Kilmer, Management Analyst, prior to purchase. (Rev. 1) Persists - Plan proposes 1.59 lb nutrient credit purchase. Comment Acknowledged. Nutrient Credit purchase will be coordinated with Ana Kilmer prior to purchase. C�4 Design Calculations and Narrative, Feb-5, 2021 (Timmons Group) 29. Culvert 4 proposed 27.5% exceeds Max. 16%. Pipe grade steeper than 16% requires anchors. Ref. VDOT drainage manual, 9.4.8.7, maximum grades. (Rev. 1) Not addressed. Though design has changed and culvert 4 does not exist, design proposes pipe 101, 1 9.74%. Provide anchor block detail, notes, narrative, sequence, etc. to guide installation of anchors for pipe > 16% slope, per VDOT Drainage Manual standards. Provide / show anchors, anchor detail, noes, narrative, sequence, etc., requisite for pipe 101 installation, for plan approval. Ref. Calc. Report, p. 5. Note: "Slopes in excess of 16% are not preferred because of the need for anchor blocks. When anchor blocks are used, they should be installed at every other pipe joint, as a minimum. (See Special Design Drawing No. A-73 and MA-73 for Anchor Details for Concrete Pipe). Corrugated pipe may be used on steep slopes in situations similar to those where shoulder slot inlets are proposed. Corrugated pipe should not be used in areas where the flow is expected to carry an abrasive bed load or that have PH and resistivity factors beyond the ranges specified in the Allowable Pipe Type Table C in Standard PC-1 of the VDOT Road and Bridge Standards. (See VDOT's Road and Bridge Standard PI-1 for Anchor Details for Corrugated Pipe). In steeper terrain, large elevation differences can be accommodated using drop structures, otherwise known as "step down" manholes, to reduce the pipe gradient . The storm system has been revised and pipe slopes have been revised to be less than 16% . 30. Design, show, and label riprap outfall protection for culverts 1 and 5. (Rev. 1) NA - Design Revised. 31. Provide LD-229, storm culvert design tables for all culverts. Avoid flow velocities in excess of 10 fps. (Rev. 1) Partially addressed. As follow- up: a. List pipe 101 outfall V 2-yr. Comment Noted. Culvert Calcs are now provided b. Provide outfall protection (OP) sized for outfall flow / velocity. Outfall protection has now been provided and called out on plans. c. Label pipe outfall riprap dimensions (L x W x D). Pipe outfall riprap dimensions are now included on the plan sheet. 32. Provide storm profiles: label INV IN/OUT, rim, etc. (Rev. 1) Addressed. 33. Label structures. Use VDOT nomenclature. (Rev. 1) Addressed. 34. Provide Nyloplast typical details, as needed. (Rev. 1) Addressed. 35. (C5.0) Provide flow arrows to indicate direction of flow in pipes. (Rev. 1) Not addressed. Flow arrows have been provided as requested. See sheet C5.0. 36. If culvert 2 passes beneath proposed retaining wall, show retaining wall in storm profile. (Rev. 1) NA - Design revised. 37. Provide design details of storm detention system; see comments elsewhere (slope, DIA, overall length, # lines, etc.). (Rev. 1) NA - Design revised; detention eliminated. 38. If storm detention is a Mfr. System (ADS, Contech, etc.). provide manufacturer recommended installation, and periodic maintenance guidelines (on the plans). (Rev. 1) NA - Design revised. 39. Ensure manways to detention system are accessible. Provide clear view of 1 5" HDPE end cap and debris cage from above, without requiring inspectors to enter 4' MH confined space. (Rev. 1) NA - Design revised. 40. Culvert 5: Outfall is shown at elev. 602', while invert out is listed as 600.0'. Revise for consistency. (Rev. 1). 41. Provide swale adequacy calculations (pre -post listed as 3.35 and 3.55 fps, respectively). Provide 10-yr swale capacity (cfs) and 2-yr swale velocity (fps) calculations. (Rev. 1) NA - Design revised. 42. Provide culvert 3 velocity / capacity calculations; see comments elsewhere re. LD-229. (Rev. 1) NA - Design revised. 43. Show, design, and label outfall protection, culvert 3. Provide channel protection, as needed, for drainage formed by proposed and existing contours downslope of culvert 3. (Rev. 1) NA - Design revised, but please see ESC Plan, item 14.h., below. Comment Acknowledged. 44. Recommend steeper slope for culvert 2, flatter slope for culvert 4. (Rev. 1) NA - Design revised. C-1.8: 45. Provide additional plan / profile data for detention system: (Rev. 1) NA - Design revised. a. Elev. base of bedding, b. Label hatch to 1 5" pipe, c. Show debris cage for 2.5" DIA orifice in end cap, d. Provide additional endcap detail (specify watertight, means of affixing to 1 5" HDPE, end cap material, etc.), e. Label culvert 5, f. Label MH diameter, g. Label / revise rectangular image in right-hand profile view of detention structure, which appears inconsistent with plan view. 46. Provide debris cage detail (2.5" DIA orifice). (Rev. 1) NA - Design revised. 47. Add .PDF image of Construction Record Drawing (As -Built) for VSMP to the plans. (Rev. 1) Addressed. 48. Submit easement plat. Easement plat must be recorded prior to VSMP / WPO202000007 approval. (Rev. 1) Review error / withdrawn. Also, SWM review item 1 ., above. New: 49. C8.0: a. Reconcile pipe 101 profile 1 2.00% slope with calc. report, p. S, pipe 101 slope 19.74%. The storm system has been updated and pipe calcs have been revised accordingly. b. Str. 104: Provide label requiring %2" steel plate in floor of MH. Per VODT Design Standard 9.4.8.7, a steel plate is only required in a manhole where the inlet pipe and outlet pipe are greater than 4' apart and the flow is either continuous live flow, carrying abrasive materials, or the size of the main pipes is 48" or greater. There is no live flow through this system and therefore a steel plate is not required for the manhole. c. Recommend Note requiring 95% compaction beneath pipe 105 / str. 106, since in fill sections. Comment Acknowledged. A note has been added to the storm profile sheet requiring compaction for structures located in fill. 50. 9VAC25-870-66.D./copied from https://law.lis.virginia.gov/admincode/title9/agencV25/chapter870/secti on66 D. Increased volumes of sheet flow resulting from pervious or disconnected impervious areas, or from physical spreading of concentrated flow through level spreaders, must be identified and evaluated for potential impacts on -down -gradient properties or resources. Increased volumes of sheet flow that will cause or contribute to erosion, sedimentation, or flooding of down gradient properties or resources shall be diverted to a stormwater management facility or a stormwater conveyance system that conveys the runoff without causing down -gradient erosion, sedimentation, or flooding. If all runoff from the site is sheet flow and the conditions of this subsection are met, no further water quantity controls are required.: a. Initial design included detention, a SWWM facility that would limit runoff without causing down -gradient erosion, sedimentation, or flooding. The design has been updated to include detention for the concentrated runoff from the proposed impervious areas in the post condition. b. Please revisit / restore stormwater management facility design to this VSMP. The design has been updated to include detention. c. Revise / delete reference in plan narrative, or calculation report that water quantity is met by sheet flow, without detention, with an ELS. Downgradient slope / contours indicate a nearly proximate existing natural conveyance channel will concentrate increased volumes of sheet flow. Acknowledged. Design has been updated. d. Sheet flow Vol. increases with this project with construction of significant impervious land cover. The design has been updated to include detention for the concentrated runoff from the proposed impervious areas in the post condition. e. Divert site runoff to a stormwater management facility or a stormwater conveyance system that conveys the runoff without causing downgradient erosion, sedimentation, or flooding. The design has been updated to include detention for the concentrated runoff from the proposed impervious areas in the post condition. f. Water quantity compliance is not met with this design; please see images below. The design has been updated to include detention for the concentrated runoff from the proposed impervious areas in the post condition. 51. Engineering urges applicant to coordinate septic field / plan review with VDH at earliest convenience: Comment Acknowledged D. Erosion and Sediment Control Plan (ESCP). Virginia Code 62.1-44.1 5:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is disapproved for reasons listed, below. The erosion control plan content requirements can be found in County Code section 1 7-402.. C-1 .5: 1. It is not apparent how proposed building4, [and] parking, and SWN! din can be built while maintaining cleaR wateF diversions. Ensure diversions and all ESC can be maintained, as proposed, throughout construction. Shown ed 1 n s ble ;nte ,l access betWeeR SR 664 and ^ n5tFUc•ien site (Rev. 1) Persists. Notes have been added to Erosion and Sediment Control Phase 2 to better convey to the contractor and planner the construction sequence that shall occur in order to maintain acceptable Erosion and Sediment Control measures until site stabilization is completed. 2. Label OP1 , OP2. (Rev. 1) NA - Design Revised. 3. Recommend initial location for staging and parking, solid waste dumpster, port-a-john, and concrete washout that does not require relocation for installation of detention system, or culvert 5. (Rev. 1) Addressed. 4. Concrete wash -out station must drain to a trapping device; show location of trapping device. (Rev. 1) Not addressed. A wash -out trapping device has been added to the Pollution Prevention Plan and called out accordingly. 5. Provide design details for level spreader (ELS) at outfall of culvert 3. Ref. VA DEQ Stormwater Design Specification No. 2, Table 2.2 for ELS design criteria (1 3 lin. Ft. per each 1 cfs of inflow). (Rev. 1) May persist. An ELS may transition concentrated release from a detention system / SWM facility to sheet flow. Provide design details for any ELS that persists as a design feature. The design has been updated to include detention for the concentrated runoff from the proposed impervious areas in the post condition. Energy balance is being met for the concentrated stormwater outfall and the ELS has been removed. 6. Include ELS, culvert 3, in SWM narrative. (Rev. 1)NA - Design Revised. 7. Label all culverts on this plan sheet. (Rev. 1) Addressed. 8. Revise CE symbol at site entrance to PCE (paved entrance). (Rev. 1) Not addressed. CE symbol has been revised accordingly 9. Provide additional existing contour labels, to aid review and analysis. (Rev. 1)Add ressed. 10. Show / label sanitary line (crossing) in culvert 5 profile (proposed san. Line from building to septic field). (Rev. 1) Not addressed. Show / label sanitary line (crossing) in pipe 103 profile, C8.0 (FM crossing x 2). The stormwater system has been revised and no longer crosses the proposed sanitary. C-1 .7: 111. Provide specific OP details (OP1 , OP2), (Rev. 1) NA - Designed revised. 12. Provide standard VDOT details: (Rev. 1) Persists. a. PB-1 (pipe bedding) b. ST-1 (safety steps) c. IS-1 (inlet shaping) Details have been added to plan sheet C1.0 New: 13. C3.1 : Provide paved wash rack detail; p.8, ACDMS - link: A paved wash rack detail has been added to plan sheet C3.1. 14. Provide ESC phase interim to phase 1 (C3.2) and 2 (C3.3) that shows phase 2 final site grading with phase 1 sediment traps: a. Phase 1 sediment traps (ST1 , ST2) control runoff from 3.82 Ac. Phase 1 ESC diversions have been designed to allow the phase 1 drainage areas to closely match the phase 2 drainage areas and notes have been added to maintain the similar drainage divide and areas to each trap through construction. b. Phase 1 indicates trap placement, diversions, but apart from ST grading, no grading, whatsoever. Correct. The existing site allows, and phase 1 diversion dikes allow for the site to drain to the proposed sediment traps without the need for additional site grading. c. Phase 2 indicates final, built condition, but no sediment traps. Sediment trap outlines and notes have been added to Phase 2 to better convey that all E&S measures must remain in place until the site is fully stabilized as also required by the sequence of installation narrative on sheet C3.0. d. The interim phase, where all site work / grading and building construction occur while STs receive diverted runoff during constructive phase, are not shown. Drainage divided and notes have been added to Phase 2 to ensure E&S measures are required and must remain until site is fully stabilized. e. No ESC information is provided for the entirety of site grading / building construction. Phase 2 has been revised to show and note E&S measures that must remain until the contributing drainage areas are stabilized. f. Phase 2presents sparse perimeter controls unequal to challenge of controlling runoff from 3.82 Ac. DA, once diverted to sediment traps, now released to newly graded fill slopes. Notes have been added to phase 2 to ensure that diversions and sediment traps remain in place until site is stabilized. Parking layout and storm have also been revised which will decrease flow from impervious areas to newly graded fill slopes. g. Final grading proposes uniform contours that in theory support sheet runoff, once stabilized. Comment acknowledged. h. Stabilization may not occur for weeks, or months. Until site is stabilized, sediment traps must operate with relocated diversions routing runoff from graded slopes to same / similar traps, with diversions designed to convey runoff to the traps. Also, please consider temporary slope drain/s. Per the E&S narrative on sheet C3.0, all E&S measures are to remain in place until site has been fully stabilized and signed off on by the E&S inspector. Notes have been added to phase 2 ESC plan to reiterate this. Divisions are located such that they can remain in place through final grading. A curb and gutter have been added along the top of the slope from the parking and a note about temporary division to a proposed inlet has been added to limit flow down slope. i. In ESC phase 2, no ESC or channel design is provided for concentrated runoff at intersection of existing grade and proposed grade at NW side of site. The total vertical fall on the NW side of the site is 40' (658' - 618'). Design permanent storm conveyance channel (may be grass -lined if velocity non -erosive / provide EC-2, EC-3 matting, as needed) where runoff concentrates. Evaluate channel velocity, and armoring (EC-2, EC-3), as needed (blue arrow below). Slope edge has been regraded to have a gradual tie into existing grade and avoid concentrated flow as much as possible. A channel calculation has been run and it is determined that the velocities are non -erosive in the final condition. See sheet C6.0 for calculation and channel cross-section. j. Please consider permanent surface water diversion to collect / divert runoff from edge of parking lot to base of slope, rather than across slope face. Design assumes slope stability, even if parking lot runoff releases across 1 5' -20' H fill slope. Sheet runoff from impervious areas across newly constructed fill slopes of this height will likely cause rill erosion, which may worsen, or prove difficult or expensive to fix, once rills established. This is a recommendation. Also, see 18-4.3.3.C.4. Curb has been added to the parking areas to reduce runoff from pavement to the slopes. k. C3.3: Perimeter controls for expanse of 1 5-20' high fill slopes are inadequate, or simply not provided. Provide adequate phase 2 perimeter controls; see image, below: A temporary diversion dike is provided in phase 1 and shall remain in place until the entire site is stabilized and approved by the US inspector. 15. C3.2: a. Label ST floor dimensions in plan view (L x W). Dimensions have been added to the Sediment Traps as requested. b. Label ST stone weir dimensions, plan view (L x W). Stone Weir dimensions have been added to the plans as requested. We have included PDF copies of the plans and calculations for your review. If you have any questions or comments, please feel free to give me a call at 434.295.5624 or email at jonathan.showalter@timmons.com . Sincerely, Jonathan Showalter, PE Project Manager