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Home My WebLink AboutWPO202100002 Review Comments WPO VSMP 2021-03-06Phone (4341296-5832 Project: Project file#: Plan preparer Owner or rep. Plan received date: Date of comments: Reviewer: COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902-4596 Fax (434) 972-4126 VSMP Permit Plan Review Avon Court Industrial Building WPO2021-000002 Scott Collins, Collins Engineering [200 Garrett St., Suite K, Charlottesville, VA 22902, scott(d�collins-engineermg.coml Avon Court Holdings LLC, P. 0. Box 1467, Charlottesville, VA 22902 [ alan(a),,riverbenddev.com ] 12 Jan 2021 6 Mar 2021 John Anderson 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 listed below. The VSMP application content requirements can be found in County Code section 17-401. 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. 1. Update SWPPP, Sec. 1, Registration Statement with rev. form, Eff. 1/l/21, Attached. 2. Revise SWPPP cover to ref. Avon Court Industrial Building, and WPO202100002. 3. Update Sec. 4, 5, once ESC /SWM plan sheets revised. 4. Complete Sec. 6.E. prior to VAR10 registration. 6.E. must list a named individual responsible for PPP. B. Pollution Prevention Plan (PPP) —A., above. The PPP content requirements can be found in County Code section 17-404. 1. SWPPP Sec. 6.A., Exhibit/s: Label rain gauge (if shown), provide Aabel rain gauge if not shown. 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. Calc. packet: 1. Revise title /other pp. of packet to identify project as Avon Court Industrial Building. 2. Include WP0202100002 on calc. packet cover. 3. Additional calc. packet comments possible, given comments on pre-dev impervious areas. Plan 4. Sheet 8 a. Pre -development SWM tables list 18250 sf (sub -area . AB-1. B-2) of exposed /bare earth land cover as impervious. Unless stone or paved, bare earth is partially pervious, it is not considered impervious. Revise table, calculations, and design, as needed. Engineering Review Comments Page 2 of 4 b. Sub -areas A, B-1, B-2 (road & parking, misc. abandoned structures, exposed /bare earth) total 127,750 sf. Beneath this, a data table titled Pre-Dev. Impervious Area Summary (For Water Quality) lists 141275 sf. Please clarify /reconcile apparent inconsistency. c. Similar to item 4.a., above, in Summary table, 26,300 sf exposed/bare earth is listed impervious. Please discuss how exposed /bare earth is impervious. If Engineering accepts exposed /bare earth is impervious in pre -developed condition, then exposed /bare earth in the post -developed condition is likewise impervious. Ensure consistency throughout plan /calculations by listing exposed /bare earth as partially pervious, even if compacted over time, or through use. Feel free to call to discuss. 5. Sheet 9 a. Sheet 7 indicates sediment trap `A' (ST `A') bottom of trap elevation =360'. b. Sheet 9 Basin A Section indicates 8.33" low -flow orifice elevation=361.50' (661.50', typo); since permanent basin A floor > ST `A' floor, please include note that ST `A' floor is to be undercut 1.0' min. to remove layer of saturated ST floor material, and backfrlled with compacted, suitable fill material ( recommend select fill). Also, see Dry Detention Basin Facility Construction Note 2. c. Check Basin A Section and Basin A Spillway for several references to 6xx.xx' elevations, and revise to 3xx.xx' elevations. d. Underground detention system `B' detail i. Please label proposed SWM facility easement. ii. Please label MH /manway downstream of weir plate. iii. Check and revise proposed SWM facility easement width to ensure width>_ 40.4', given Contech sheet 10 backfrll requirement minimum trench width = 1.51) + 12" (16'). Also, please see ACDSM easement diagram, p. 15., and sheet 9 UGD system profile showing 2.2' cover (7.2' x 2 =14.4' + 10' landing: 16' + 14.4' + 10' =404). E ENMNT MMTH. DW ETEa. I'. x IHBIar sM'.%Mj e. UGD system bypass: i. Revise Str. 2 II-IO elevations slightly, since vertical interval =4', and VDOT drainage manual requires steel plate in floor of MH if step-down vertical interval >_4'. ii. Revise Str. B7 slope slightly to avoid need for VDOT anchors for pipe slope >16%, proposed slope=18.75%. iii. Recommend note /label with leader line to fill section beneath Str. B7 requiring 95% compaction, since pipe B7 is in fill section. f. Underground detention system `B' detail /UGD system profile: Since sediment basin `B' floor elevation=362.0' and UGD system INV out=364.5', provide note at these details (and revise sheet 3 sequence of construction) to require over -excavation of sediment basin `B' once upslope areas are stabilized and SB is removed for UGD system construction. Note to require excavation to a depth of 361.0' minimum and require select backfrll material beneath all portions of the UGD system that overlie former SB floor. The limit of over -excavation is point at which sediment basin profile intersects elevation=365.5', at which point, contractor excavates depth required to install Engineering Review Comments Page 3 of 4 Contech detention system. Goal: excavate 21' lower than floor /sidewalls of sediment basin, wherever UGD system intersects SB footprint to remove saturated sediment basin floor material. 6. Revise per SDP202100003 Engineering review comments, 2/10/21, review items 6.a., Ta.-i. which are relevant to WPO202100002 design. 7. Submit FDP Application for manmade conveyance to a natural watercourse. FDP approval is required prior to WPO plan approval. 8. Conveyance channels (for dry detention and UGD system) require easement across City of Charlottesville parcel. Obtain and record easement prior to WPO plan approval. 9. Note: Albemarle County cannot approve SWM design that may cause erosion across City of Charlottesville property. 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 and sediment control plan content requirements can be found in County Code section 17-402. 1. Sheet 7 a. SB emergency spillway in fill section is impermissible. Ref. VESCH, 1992, p. I1I-86, link: Chapter 3 - Standard & Spec 3.14: Temporary Sediment Basin (virginia.eov) Location The emergency spillway channel shall be located so that it will not be constructed over fill material. The channel shall be located so as to avoid sharp turns or bends. The channel shall return the flow of water to a defined channel downstream from the embankment. b. Show /label SB barrel collars in sediment basin `B' detail. c. Sediment Basin `B' detail: please label baffle length. 2. Sheets 4.5.6 a. Increase pitch of SSE labels, so readable at print plan scale. b. Label SAF on east side of SB `B'. 3. Across plan sheets: Coordinate slopes to be removed from the steep slopes overlay district with Engineering. Physical survey is required to remove slopes from the steep slopes overlay district. The VSMP permit application and all plans may be resubmitted for approval when all comments have been satisfactorily addressed. Please provide digital version of revised plan /SWPPP with a completed application form. Process: After approval, plans will have 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 have to be completed by the owner and submitted along with cash, certificates or sureties for the amounts specified. The agreements will have to be approved and signed by the County Attorney and County Engineer. This may take 24 weeks to obtain all the correct signatures and forms. Stormwater Management Facilities Maintenance agreements will also have 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 have to be submitted along with court recording fees. Project requires (prior to WPO plan approval): • FDP Application review and approval. • SWM facility and access easement (deed + plat) recordation. • Public drainage easement across City of Charlottesville TMP 07700-00-00-00700 for two SWM Engineering Review Comments Page 4 of 4 facility outfalls. • Coordinate steep slopes to be removed from the steep slopes overlay district with Engineering. After bonding and agreements are complete, county staff will 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 have to be paid directly to the state. For fastest processing, this is done electronically with the emails provided on the application. 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. After DEQ coverage is issued, via the coverage letter, the County can hold a pre -construction conference. Applicants must complete the request for 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 joint V SMP and 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, httr)://www.albemarle.orp/deDtforms.asD?deDartment7=cdengwoo "'PO202100002 Aeon Court Industrial Building 030621