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Home My WebLink AboutWPO201600007 Review Comments 2018-09-18 ` 3 . . . • PROJECT MANAGEMENT CIVIL ENGINEERING 5� . LAND PLANNING : ENGINEERING • f' . September 18th, 2018 • Matt Wentland Civil Engineer II County of Albemarle - Engineering Regarding: Inglewood Terrace—WPO-2016-00007 VSMP Comment Response Dear Mr. Wentland, Thank you for your review of the WPO Plan for Inglewood Terrace. We have revised the plans per latest comments dated August 31, 2018. Please find below a detailed response letter describing the changes we have made to the plans per each of your comments. A. Stormwater Pollution Prevention Plan(SWPPP) 1. No SW.PPP was included with the submittal and needs to-be-provided. a, Comment not addressed. (Rev 2) Comment Addressed, 2. (Rev 2) Provide a.signed certification with the SWPPP. • The signed certification has been provided. B. Pollution Prevention Plan(PPP) . The PEP appears to be acceptable at this time. C. Stormwater Management Plan(SWMP) 1. Show soil data on the plan • a, Comment adddrecsed. • 2, Due to two rob`licd g stream studies. Staff requests that a third study be performed, rr ,c, either by a'third party agreed upon byboth thehomeowners 'in th de� er ! `S Army CorpsEngineers. �� jand the developer orthe US rrf,! of t..r�I:,=.ers. This third study will determine whether or not a buffer will ha placed on the parcels in question and on all parcels downstream of the site. a. Comment nddimessred. 3. include, all necessary hydrologic end hydraulic analysis for the site, including the VFiR ( worksheet pi for Redevelopment and verification the channel leaving .h, site s ac'ec te. a. Comment partially addressed. include the stormwater Conveyance culvert on the i.."D-229 worksheef STR CSD to S'I R ! > also appears to be entered incorrectly on the ;i?orks`heet. T nutrient credits need to r Kilmer ;1utr�.,iu�:re�l,il ':�Jlli ric;:;'.i be j�i.IrCil�iSC:C, before plan =��prOVal Please contact Ana for information on required documents and formatting. • b. (Rev.2) Please contact Ana Kilmer prior to purchasing the 1.16 lbs. of nutrient credits. Ana Kilmer will be contacted prior to purchasing the 1.16 lbs of nutrient credits. 4. Verify- that the pipe profiles are correct. P2 and B3 appears to be shown and labelled incorrectly on the profile, view. The stub-out is not showing or; C4. a. Comment not addressed, Drainage information has been removed from the plan. Please provide plan and profile information for the drainage system including a drainage area. map for the inlets. Provide details on the weirs/orifices for the detention system and show how the 60, and 72" pipes will be connecting to the that are shown. b. (Rev.2) Provide more details on the JB-1's; including the height of the boxes and the type of tower on each. It appears that both B2.and B3 are shown as being above grade, is this intended? The JB-1 structure details have been provided on the.profile on Sheet C7. • More detail will be needed where A,4'and C4 connect to the retaining wall. a. Comment partially addressed. Retaining -wall/headwall designs will be needed before - approval. A4 also does not appear to continue through to the lower wail on the plan sheets. b. (Rev.2) Response noted. See comment 9 below. Acknowledged. . 6. A, has a 4' drop and a 90 degree turn. Provide a hydraulic profile to verify this will work during larger storms. •a. Comment addressed. 7. The curb cut on the turnaround is discharging runoff onto the fill slope. The slope will need to be protected from erosion. a: Comment partially addressed, the current grading shows a ridge in the middle of the swale. b. (Rev.2) Comment not addressed, the turnaround (located above ST-1) is still showing a curb cut and hatching leading to the inlet. Provide more detail around the inlet as it currently appears the drainage will not be intercepted by the inlet. The top is also called out as 51.5.54 while the proposed 514 contour runs near the middle of the inlet and the 512 contour runs along the edge of the inlet, leaving A2 exposed. The drainage ditch to A2 has been revised to adequately convey water to the drop inlet. The grading and spot elevations around it have been revised:as well. 9. Provide a Stormwater Maintenance agreement for the site. a. Response noted. b. (Rev.2) The agreement has been forwarded to Ana Kilmer. Acknowledged. 9. Provide plans'tor the retaining wail and verification-that there is no issue with the wall and wail foundation being submerged duringstorm events. It appears the 100 storm t overtops psthe l .: IJ;'.C�1.r� .n.� i ),,yl Qrlii event ..av, i`l�r�,., wail and runs into the buildings Jn the noigh)Ur:nC pro pErtl. a, Comment partially addressed, Retaining wall plans ili be required before approval as the travel way and townharne construction is dependent on the walls and to ensure that wall ll construction Goes not affect the neighboring property behind Lot ;?, • b. (Rev.2) Response noted. Retaining wall designs will be needed prior to plan approval. A grading permit will not be issued until VSMP, road, and Final Site Plans are approved. Page 1.2 • Acknowledged. 10. (Rev.2) All areas-used as Forest and Open Space on the VRRM worksheets will n.eed.to be shown and labelled as SWM Forest&Open Space Easement. The following note will need to be placed on the plan: "..." • The note has been included on sheet C5 and the SWM Forest&Open Space areas have been labelled. 11. (Rev.2)At the time of final plat submittal, a Deed of Dedication will need to be signed and recorded for the SWM facility easements and the SWM.Forest and Open Space easements. This will filled out by the County and forwarded to the applicant when the final plat is nearing approval. Acknowledged. 12. (Rev.2) Show parcels,.owner and TMP information for all properties as they exist today. The parcels and parcel information have been shown on Sheet C5. D. Erosion and Sediment Control Plan(ESCP) t. - Additional erosion control measures should be used below ST 1 to ensure runoff does not enter the neighboring property. Demonstrate how 'l will function during conhttruction, it appears that is Will be filled in almost immediately when the storm system and fill slope are installed. a, Comment not addressed. Site does not appears adequately protected thouah all stages of • construction. It is also recommended that offsite grading easeme are t;e u..is� ntS acquiredwhen n grading within 5' of the property line. Please schedule a meeting to discuss. b. (Rev.2)-See comments below. Acknowledged. ,tel 2. (Rev.2) Show the full grading for the sediment traps on the plans. As shown,the proposed trap • elevations will:not tie into the existing contours. Also show the drainage area to the traps. • The sediment trap grading has been shown tied into the existing contours. .13. (Rev.2) Provide safety fence along the limits of disturbance next to the neighboring property in the western corner of the site. The safety fence has been provided for Phase 1 &2 of the ENS plan. • '4. (Rev.2) Provide silt fence between the limits of disturbance and the diversion dikes along the southeast and southwest property lines. Silt fence has been added between the limits of disturbance and the diversion dikes. 5. (Rev.2) For diversion dikes with slopes greater than 2%, the channel shall be stabilized in accordance with Spec. 3.17, Stormwater Conveyance Channel. Show the type of stabilization and the detail on the plans. Revise diversion dikes that are shown flowing uphill. Erosion Control Matting has been provided on the plans for each diversion dike with a channel slope greater than 2%.: The EC-2 and EC-3 details have'been provided on Sheet C7. The diversion dikes have also been revised to not be shown flowing uphill. 6. (Rev.2) Show the Clean Water Diversion detail on the plans. The Clean Water Diversion detail is included on-Sheet C7. Page j 3 7. (Rev.2) Show the Outlet Protection design and dimensions on the plans. The Outlet Protection design nomograph and dimensions are shown on the Sheet C7. 8. (Rev.2) Provide additional measures below ST-2 and 3 to limits the sediment entering the public street and to slow the water,before it reaches the existing inlet so it does not bypass the inlet. Provide Inlet Protection for inlet located across Inglewood Ct. A 6'x 12' rip-rap outlet protection has been added to the diversion dike to slow the water before entering the inlet. 9. (Rev.2) Provide import/export quantities. If import or export exceeds 10,000 CYs, provide permit information for offsite borrow/waste area. An import/export quantity analysis has been included with this submittal. A total Export Volume of 627 CY was determined,therefore a permit will not be required. 10. (Rev.2) Provide a temporary right-of-way diversion at the entrance to the site at Inglewood Dr./Ct. A temporary right-of-way diversion and detail has been included on the site plan. If you have any questions please feel free to contact me via e-mail at michael@shimp-engineering.com or Justin Shimp at Justin@shimp-engineering.com or by telephone at 434-227-5140. Sincerely, • Michael Chandler Shimp Engineering, P.C. PageI4 • Cut & Fill Analysis - Volumes by Triangulation Export Volume: 626.7 C.Y. Cut volume: 4,463.93 C.Y., 4,821.05 Tons Fill volume: 3,837.20 C.Y., 4,144.18 Tons Area in Cut:. 32,869.9 S.F., 0.75 Acres Area in Fill: 27,148.6 S.F., 0.62 Acres Total inclusion area: 60,126.5 S.F., 1.38 Acres Average Cut Depth: 3.67 feet Average Fill Depth: 3.82 feet Cut to Fill ratio: 1.16 Elevation Change To Reach Balance: 0.281 Volume Change Per .1 ft: 222.7 C.Y. Density: 80.00 (Ibs/ft"3) Cut (C.Y.)/Area (acres): 3234.00 Fill (C.Y.)/Area (acres): 2779.95