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HomeMy WebLinkAboutWPO201900021 Review Comments WPO VSMP 2019-05-08COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902-4596 Phone (434) 296-5832 Fax (434) 972-4126 VSMP Permit Plan review Project: UVA Research Park Loop Road — VSMP Plan Plan preparer: Jonathan Showalter, Timmons Group f onathan.showalter(a timmons.com] 608 Preston Ave., Suite 200 / Charlottesville, VA 22903 Owner or rep.: University of Virginia Foundation / P.O. Box 400218 Charlottesville, VA 22904 [tmarshallAuvafoundation.com] Plan received date: 25 Mar 2019 Date of comments: 8 May 2019 Reviewer: John Anderson WP02019-00021 County Code section 17-410 and Virginia Code §62.1-44.15:34 requires the VSMP authority to act on any VSMP permit by issuing a project approval or denial. This project is denied for reasons outlined, below. The application may be resubmitted for approval if all comment items are satisfactorily addressed. A. Stormwater Pollution Prevention Plan (SWPPP) The SWPPP content requirements can be found in County Code section 17-405. A SWPPP must contain (1) a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL measures necessary. a. Sec. 1 (Registration Statement): Revise to include: i. An e-mail address for Todd Marshall, UVA Foundation ii. Registration Statement signature b. Sec. 9 (Signed Certification): Please sign c. Sec. 11 (General Permit Copy) Please include 2014 VAR10 d. List WP02019-00021 on cover of SWPPP The PPP content requirements can be found in County Code section 17-404. 1. If Sec. 6 PPP Exhibit is revised, please provide an updated Exhibit 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. Revise plan title to include ref. to VSMP /WP020900021. VSMP Plan and Road Plan Design Calculations & Narrative, 3/25/19: a. SWM Quantity Narrative —Include information highlighting (via prior -approved graphic, narrative, zoning, site, or WPO data) how eastern side of project drains to a large wet pond that was designed to handle stormwater quantity for the full build out of the research park. Recommend information identical to Timmons Group Lewis and Clark Drive Road Extension VSMP Plan and Road Plan Design Calculations & Narrative booklet, d. 3/25/19, pg. 18-19. b. LD-229: Provide computational data requested at D. ESC Plan, items 7 and 8. Engineering Review Comments Page 2 of 7 c. Revise SWM routings — see items 14, 15, below. 3. Ensure dry pond design details on VSMP /WPO match design details on SUB201900049, or preferably limit design detail provided for dry pond on the Road Plan to conceptual outline, saving details for the VSMP /WPO Plan. 4. Show proposed SWM Facility /Access /Drainage Easements. S. Provide curb break /mountable curb to provide SWM Facility Access (ACDSM, pg. 12). Provide access label or note on plan and linework with proposed grading that meets ACDSM standard, text image, below, for dry pond Access: Best Management Practices for Stormwater Management: All practices must have adequate vehicle access; 10' width graded at less than 20%. Anything over 20% must be surfaced with gravel or pavement. Access must be to all structures and forebay cleanout areas. Easements must be provided over all access and facilities, to accompany deeds and agreements as available on the county website; http://www.albemarle.orgLdeptforms.asp?department—cdengiypo 6. Provide typ. detail, transition from CG-6 to mountable (rolltop) curb at point of SWM facility access. 7. Recommend ref. SUB201900049, UVA Research Park Loop Road (Road Plan), on C0.0. 8. Sheet C 1.1 is not strictly necessary. Recommend remove this sheet from the VSMP /WPO Plan. 9. C1.2: Provide VDOT IS-1 detail (inlet shaping). 10. C4.2, C4.3 are not strictly necessary. Recommend remove these sheets from the VSMP /WPO Plan. 11. C5.3 is not strictly necessary. Recommend remove this sheet from the VSMP /WPO Plan. 12. C6.1 /Stormwater Quality: VSMP Plan and Road Plan Design Calculations and Narrative (booklet) 3/25/19 submitted with SUB201900049 does not appear to include runoff reduction spreadsheet (VaRRM .xls); apparently no booklet submitted with WP0201900021. Provide VaRRM .xls. (Only booklet ref. to Water Quality in booklet, image below-::pg. 3) Water Quality: The current site is undeveloped. 4.66 acres of disturbed area was analyzed for water quality. There will be 1.08 lbslyear to be treated via manufactured treatment device. The remaining 0.22 lbs/yr of required nutrient credits area to be purchased from a DEQ- Approved Nutrient Credit Bank in Accordance with CA code 62.1-44.15:35. 13. Note: Applicant must coordinate nutrient credit purchase with Ana Kilmer, Albemarle County, once plan review comments are addressed prior to purchasing credits. Purchase of nutrient credits is required for VSMP plan approval. 14. C6.1: A fair portion of the 3.10 Ac. off -site post -development area cannot reach the dry pond without inlet west of N-S leg of loop road similar to inlet south of E-W section of the loop road. See images, below (blue outlined area). Please provide inlet /pipe connection to route this off -site runoff to the dry pond, to qualify for quantity compliance as well as to collect flow at an otherwise low -point that lacks drainage outfall, unless runoff is to sheet over the curb onto the paved surface. Engineering Review Comments Page 3 of 7 { ROUTED AREA: POST -DEVELOPED ROUTED AREA = 3.10 ACRES DRY POND AREA: CN = 61 AREA = 1.59 ACRES TC = 12.6 MIN. CN = 84 TC=6MIN. � a r , � ' ���i� W 1.. � ` `�.�• y ,COI ,6! POST -DEVELOPED UNROUTED AREA: AREA 055 = .E, b a. 1 o ACRES e • r CN _ — 74 • fr �� TC=6MIN. - POST -DEVELOPED WATER QUANTITY CALCULATIONS FOR DISTURBED WATI AREA TO THE NORTH: SUMM, REDEV CHANNEL PROTECTION (ENERGY BALANCE): FLDOD PROTECTION: DISTMBE D.Wr__sanA—'W— Iw—_POST-DF ELOPED Duos PRE-DF4 LOPED O,o POST-m OA9 J9.i1 CFS' OAST AUffD I IG.137 AG )-9,W CF IOFB9 R DMU" -124 CFS C5.1: offsite routed low point without collection — blue circle /highlight (contour 576'±): 15. Ensure plan CN /Acreage match routing report values. Sub -catchment 3S, 9S report values do not match plan data. Revise routings, consistent with plan sheet C6.1. /ref. images: Engineering Review Comments Page 4 of 7 Preliminary Type ff 24-hr f Year Rainfall=2.97" Prepared by Timmons Group Printed 3/25/2019 HydroCAD® 10,00-20 sin 06538 © 2017 HydroCAD Software Solutions LLC Pane 6 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Slor-Ind method Subcatchmentl S: Pre Developed in LOD Runoff Area=2.500 ac 1.20% Impervious Runoff Depth>0.30" Tc=12.6 min CN=61 Runoff=0.77 cfs 0.062 of Subcatchment3S: Post Developedin LOD Runoff Area=1.700 ac 41.18 % Impervious Runoff Depth>0.90" //Tc=6.0 min CN=76 Runoff=2.92 cfs 0.127 of Subcatchment5S: Undisturbed Offsite Runoff Are 3 0 ac 0.00% Impervious Runoff Depth>0.30" Flow Length=480 Tc=12.6 min C61 Runoff=0.96 cfs 0.077 of Subcatchment8S: Undisturbed Offsite Runoff Area-3.100ac 0.00%impervious Runoff Depth>0.30" Flow Length=480' Tc=12.6 min CN=61 Runoff=0.96 cfs 0.077 of Subcatchment9S: Unrouted Runoff Area=0.400 ac 0.00% impervious Runoff Depth>0.30" Tc--6.0 min CN=61 Runoff--0.16 cfs 0.010 of Pond 9P: Dry Pond Peak Elev=569.11' Storage=2,179 cf Inflow=3.40 cfs 0.205 of Outflow=1.11 cfs 0.199 of Link 61_: Area to the Southeast Inflow=1.74 cfs 0.140 of Primary=1.74 cfs 0.140 of Link 7L: Area to the Southeast Inflow=1.160s 0.209af Primary=1.16 cfs 0.209 of POST -DEVELOPED OFFSITE ROUTED AREA: POST -DEVELOPED ROUTE AREA = 3.10 ACRES DRY POND AREA: / CN=61 AREA = 1.59 ACRES TC=12.6MIN. CN=84 TO = 6 MIN. r 1 + r 1 �• POST -DEVELOPED » UNROUTED AREA: AREA = 0.55 ACRES CN=74 ±i. TO = 6 MIN_ - ---- — — POST -DEVELOPED _ t .�J" iS ` � undisturbed onene " 6L - eveloped.n LOD (/8S ( S Area to the Southeast Undisturbed Offsile 9P . Developed in LO Dry �� O 9S 7L a— Unrouted Aree to the South st 16. L1.0: VDOT Std Class Al riprap dimensions need not appear on this sheet. 17. L1.0: Recommend shift leader line of label reading `Tie to nearest inlet (Typ.)' to more clearly indicate UD-4 (Typ) is to tie to nearest inlet. Engineering Review Comments Page 5 of 7 18. Choose BMP practice from approved list, or an approved proprietary measure a. Use plan labels that identify /match a best management practice listed at https://www.swbmp.vwrrc.vt.edu/ (text image, below): " 2011 DESIGN SPECIFICATIONS FOR PRACTICES 1-15 • Practice 1: Rooftop (Impervious Surface) Disconnection • Practice 2: Sheet Flow to Veg. Filter Strip/Conserved Open Space • Practice 3: Grass Channels • Practice 4: Soil Compost Amendment • Practice 5: Vegetated Roof • Practice 6: Rainwater Harvesting • Cistern Design Excel Spreadsheet, v. 2.1 (March 2013; file size: 22 MB — Note: File is too large to preview. Download file to use it.) • Technical Memorandum: Virginia Rainwater Harvesting (March 25, 2013; pdf) • Practice 7: Permeable Pavement • Practice 8: Infiltration Practices • Practice 9: Bioretention (including Urban Bioretention) o Bioretention Photo Tutorial (pdf) • Practice 10: Dry Swales • Practice 11: Wet Swale • Practice 12: Filtering Practices • Practice 13: Constructed Wetlands • Practice 14: Wet Pond • Practice 15: Extended Detention (ED) Pond b. If design proposes an Extended Detention (ED) Pond, use link to visit the Clearinghouse and carefully consider design criteria listed at VA DEQ Stormwater Design Specification No. 15, Section 6, including: i. 6.1 — Overall Sizing ii. 6.2 — Treatment Volume Drawdown and Detention Design iii. 6.3 — Requied Geotechnical Testing iv. 6.4 — Forebay Design v. 6.5 — Conveyance and Overflow vi. 6.6 — Internal Design Features vii. 6.7 — Landscaping and Planting Plan viii. 6.8 — Maintenance Reduction Features ix. 6.9 — ED Pond Material Specifications c. Provide detailed plan and profile for a listed practice that meets design criteria. d. Provide Landscaping and Planting Plan Example of partially approved Ex. Det. Pond profile /recent VSMP /WPO Plan submittal (photo, below): 19. Additional SWM Plan (VSMP /WPO) review comments possible, once plan re -submitted. Engineering Review Comments Page 6 of 7 X Artiseep Collar X-8 n79*s DETENTION D. Erosion and Sediment Control Plan (ESCP) Virginia Code §62.1-44.15:55 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 17-402. 1. C3.1: Provide Paved Wash Rack detail (ACDSM, pg. 8) C3.2: 2. Show break in SSF at stone weir outfall, ST2. 3. Label ST1, ST2 stone weir dimensions (L X W) in plan view. 4. C3.3: Provide Str. # consistent with C3.0 Phase II Sequence. 5. Cannot locate temporary 15" HDPE pipe. Edit /revise C3.0 Phase I sequence, as needed. 6. C3.3: Check C3.0 Phase II sequence Note 2.1 against C5.0. Revise if pipe /str. ref. should be Str. 300, 301. 2.1. ONCE THE CONTRIBUTING DRAINAGE AREA TO SEDIMENT TRAP #1 HAS BEEN PERMANENTLY STABILIZED AND APPROVED BY THE ESC INSPECTOR, REMOVE SEDIMENT TRAP #1. CONTRACTOR TO ENSURE SILT FENCE ALONG THE TOE OF SLOPE IS INSTALLED AND IN GOOD CONDITION AT ALL TIMES TO ENSURE EXISTING WETLANDS ARE PROTECTED. ONCE THE STORM SYSTEM ASSOCIATED WITH DRY DETENTION BASIN IS OPERATIONAL, REMOVE THE TEMPORARY 15" HDPE PIPE AND END SECTION. INSTALL STRUCTURE 402 AND PIPE 401 ACCORDINGLY. 7. LD-229 submitted with SUB201900049 does not appear to include design computations for pipe 301. Evaluate design flow and discharge velocity against pipe capacity and riprap outfall dimensions. 8. Evaluate discharge velocity against riprap outfall, Str. 200 /VDOT ES (capacity appears sufficient). The VSMP permit application and all plans may be resubmitted for approval when all comments have been addressed. For re -submittal, please provide .PDF preview prior to print submittal. Engineering plan review staff is available from 2-4 PM on Thursdays if you wish to meet to discuss this review. Engineering Review Comments Page 7 of 7 Process After approval, plans will need to be bonded. The bonding process is begun by submitting a bond estimate request form and fee to the Department of Community Development. One of the plan reviewers will prepare estimates and check parcel and easement information based on the approved plans. The County's Management Analyst will prepare bond agreement forms, which will need to be completed by the owner and submitted along with cash, certificates or sureties for the amounts specified. The agreements will need to be approved and signed by the County Attorney and County Engineer. This may take 2-4 weeks to obtain all the correct signatures and forms. Stormwater Management Facilities Maintenance agreements will also need to be completed and recorded. The County's Management Analyst or other staff will prepare the forms and check for ownership and signature information. The completed forms will need to be submitted along with court recording fees. After bonding and agreements are complete, county staff will need to enter project information in a DEQ database for state application processing. DEQ will review the application information based on local VSMP authority approval. At this time, the DEQ portion of the application fees will need to be paid directly to the state. For fastest processing, this is done electronically with the emails provided on the application (SWPPP Registration Statement). DEQ should notify applicants with instructions on how to pay fees. When DEQ approves the application, they will issue a permit coverage letter. This should be copied to the county. Easements must be recorded prior to VSMP approval. Proof of purchase of nutrient credits is required for paln approval, and to receive a Grading Permit. After DEQ coverage is issued, the County can hold a pre -construction conference. Applicants will need to complete the request using a pre -construction conference form, and pay the remainder of the application fee. The form identifies the contractor and responsible land disturber, and the fee remaining to be paid. This will be checked by county staff, and upon approval, a pre -construction conference will be scheduled with the County inspector. At the pre -construction conference, should everything proceed satisfactorily, a grading permit will be issued by the County so that work may begin. County forms can be found on the county website forms center under engineering; hlW://www.albemarle.orp-/deptforms.asp?departinent--cdengno Ifyou have questions /concerns, please contact me at janderson2@albemarle.org or at 434.296-5832-x3069. Thank you J. Anderson, Engineering Div. WP0201900021 UVA Research Park Loop Road 050819