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Home My WebLink AboutWPO201300032 Review Comments WPO VSMP 2018-10-02COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902-4596 Phone (434) 296-5832 Fax (434) 972-4126 Project: Plan preparer Owner or rep.: Received date: (Rev. 1) (Rev. 2) (Rev. 3) Date of comments: (Rev. 1) (Rev. 2) (Rev. 3) Reviewer: VSMP Plan review Amendment Cascadia Blocks 4-7, Final ESC and SWM Plan Amendment Jimmy Taggart, PE; Dustin Greene, EIT—Roudabush, Gale & Associates, Inc. [JTaggart&roudabush.com; dareene&roudabush.com ] 172 S. Pantops Drive, Charlottesville, VA 22911 Cascadia Development LLC [ 170 S. Pantops Drive, Charlottesville, VA 22911 ] Charlie Armstrong (carmstrong(asouthern-development.com ) 24 May 2018 (ref. RMS) 24 Jul 2018 (ref. RMS) 23 Aug 2018 17 Sep 2018 6 Jul 2018 (email; denied) 24 Jul 2018 (email; denied) 24 Aug 2018 2 Oct 2018 John Anderson SWPPP, ESOP, Mitigation Plans not reviewed with this correspondence —NA (SWM Plan Amendment) WP0201300032 —Amendment to: eliminate biofilter #2; construct grass swales; plant steep slopes A. Stormwater Pollution Prevention Plan (SWPPP) —NA B. VSMP: SWPPP: Stormwater Management Plan (WP0201600009) VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This plan is disapproved; please see comments below. The stormwater management plan content requirements can be found in County Code section 17-403. 1. SW 1: Delete second paragraph of text in cloud revision block; sentence beginning "Biofilter #2 is being removed with this VSMP Amendment..." Do not edit or replace with similar text; sentence is ambiguous, unnecessary and somewhat confusing. (Rev. 3) Addressed. 2. Coyy Erosion Stabilization Area legend from SW 16 to SW 13A and SW 15, to clarify that symbol indicates areas of erosion stabilization; recommend lower right-hand corner placement, each sheet. (Rev. 3) Addressed. 3. SW13A: Revise match line sheet reference, or include sheet SW1313. (Rev. 3) Addressed. SW15 4. If biofilter # 1 planting plan, dimensions, materials, etc. have changed, include narrative description of design revision to biofilter #1, and enclose with cloud revision (Rev. 3) Addressed. Engineering Review Comments Page 2 of 3 5. If culvert B is new with plan Amendment, provide culvert B profile in cloud revision. (Rev. 3) Addressed. Applicant response: `The developer has provided a rip rap channel all the way down to the edge of the creek with a pedestrian bridge.' 6. Since culvert A inlet is a sag low point where grass Swale #1 and #2 meet, provide grate inlet, since inlet appears to be flush with point of intersection of these swales (grate inlet design warranted). (Rev. 3) Partially addressed. Applicant response, in part, `...ES-1 has been added to help direct flow into and through culvert A.' As follow-up, ES-1 does not appear to be shown on plans. Provide ES-1 in plan view; add label /leader line. Feel free to contact reviewer, if review error. 7. Reference to VDOT Al check dam in grass swale profile is misleading. Check dams are constructed above -grade to check flow, while this feature is shown below grade with label reading `toe protection.' If feature is a check dam, revise profile to show check dam rising above level of bottom of Swale, immediately downslope of gabion baskets. If this is a subgrade non -erodible measure to prevent scour, revise label, and delete reference to check dam. In either case, provide detail to guide construction, installation, and inspection of this measure (multiple proposed). (Rev. 3) Addressed. Applicant response: `Grass swales #1 and #2 have already been built. We will provide as-builts at the end of the project.' 8. Calculate Vz-year, Max., grass swales #1 and #2. Provide and specify soil stabilization blanket, as /if needed. (Rev. 3) Addressed. 9. Retaining wall, Max. Ht. =2' is proposed. Provide retaining wall plan /profile views and detail, including block dimensions, subgrade design, drainage, etc., to guide construction and inspection. (Rev. 3) Addressed. Applicant response: `The developer has graded out the 2' retaining wall. Grass swales #1 and #2 have already been built. We will provide as-builts at the end of the project.' 10. Provide deed book -page reference for `Var. Width Trail, SWM Access & Maintenance, and Stream Buffer Mitigation Easement' shown in Grassed Swale and Outfall detail. (Rev. 3) Not addressed. Provide bk.-pg. reference for recorded easements. Comment response and plan revision reference bk. 4565-pg 413, a recorded SWM Maintenance /BMP Facilities Maintenance Agreement. Easements shown on WPO201300032 were likely recorded with subdivision plat for these blocks. Please provide bk.-pg. reference for plat showing easements for these blocks, as initially requested. 11. SWM Maintenance Agreement and Deed of Dedication with Easement plat for grassed swales must be recorded prior to Amendment approval. (Rev. 3) Addressed. 12. Label height of gabion basket in Grass Swale detail. (Rev. 3) Addressed. Applicant response: `Grass swales #1 and #2 have already been built. We will provide as-builts at the end of the project.' 13. Provide gabion basket detail. (Rev. 3) Addressed. Applicant response: `Grass swales #1 and #2 have already been built. We will provide as-builts at the end of the project.' 14. Culvert A profile references detail 6/SW 13 (riprap outlet protection); SW 13 and detail 6 do not appear to be included with Amendment. Provide riprap detail with L X W X D dimensions, as well as class of riprap stone. (Rev. 3) Addressed. Applicant response: `Approved rip rap dimensions have been shown on SW15. We will provide as-builts at the end of the project.' 15. Section A -A references 3' weir, swale #2; elsewhere, weir calculation lists weir length = 2'. Please reconcile. (Rev. 3) Addressed. 16. SW16: Provide bare root seedling or whips quantity (count), at 1,210 per acre. Provide estimate of area to be planted (ft2). (Rev. 3) Partially addressed. As follow-up, SW 16 planting information is inconsistent and incorrect (see photo image, below). Table B (and rev. plans) indicate whips at 1,210 per acre. Revised plans indicate 6' X 6' spacing (36 SF grid; this is accurate); plans also reference 400sf spacing, which is inaccurate. Plans propose 61.1 seedlings/whips, which is too few. Revise plant count, per Table B, DCR Riparian Buffer Guidance Manual. SW 16 makes ref. to 24,450 SF Area to be Planted; Mitigation Area Required, 49,742 SF; Mitigation Areas Provided, 51,150 SF. These multiple references are unclear. Recommend call to discuss. Also, please clarify that Ernst Seed Mix 181 is to be applied to Erosion Stabilization Areas, rather than `provided on slopes.' Clari that Erosion Stabilization Area totals 24,450 SF, if this is the case. Ref. Table B, DCR Riparian Buffer Guide. Engineering Review Comments Page 3 of 3 N A 1 STREAM BUFFER MITIGATION PLAN SW16 ERNST SLLD Mix 181 TO BE PROVIDED ON SLOPES SEED RATE: 60LES PER ACRE Sheltered bare root seedlings or whips to approximately 20' x 2t)' on center per VDOF for j9nkion Pllml'nps STREAM BUFFER DISTURBANCE: M!t'' 4 soil stcbilization- (bare rant madings or whips at 1,210 per acre, Area to be Planted: 24,450 sgft oppraximately Impact Area 1: 12,432 SF cenle[� 24,450/400 st = 51.13 seedlings/whips mppci Areo 2: 11,111 SF A edl im to Ln qe Occiduaog Trees 24,871 SF Acer rubrum Red Maple 62 sheltered bare root seedlings \ Betula lento Black Gimh or whips ka be provided. ] Liquidamdor styrociflua MITiGAl10N AREA REf,1UIRED: 5weetgum !/ 2 x IMPACT AREA Sredl Canoov/Understary Trees \ y 2 x 24,871 SF = 49,742 SF A-dwchier canadensis Servicsberry ,e Cercis canadensis Redbud J Mognolio Al MITIGA7i0N AREAS PROVIDED: S weetboy MognWia 51,150 Sr Mognolio grondilloro Sauthem Magnolia Evsrarse_,s_ryrvbe- Kolmia lolilalio Mountain mural Rhaaadendron vrsco Swamp Azalea Taken from "Riparian Buffers Lame 5h e. Motlilicalion and Mitigation Carnus sloleeif,ro Redtw;g 0.9.00d Guidance Manuul" by OCR, rtomomalra wryin;ona common HStmnaze; hopter $-1. Relorestation/ „5r„ a Snr„hs Eslnblishmenl Table 8. 5—year Gahm oiniloira maintenance and perlormonte 5-1 ps,'sr,'e guarantee required. Herbaceous Pl�.,r� Chalons lyonii Aink rurlleheup t iris ttisiaslo Lobelia rdMelis PotlophyYum pefketum Crssled CorwnN Flo— Moyvpple Please Note: A Mitigation Plan bond is required, but cannot be calculated until plant count is resolved /plans revised, consistent with Riparian Buffer Guidance Manual, Table B. Please call if any questions. 17. SW18: Revise leader line location, Grass Swale #2. (Rev. 3) Addressed. 18. SW 18: Provide cloud revisions for revisions. (Rev. 3) Addressed. C. VSMP: SWPPP: Erosion Control Plan (WP02016-00009) —NA D. Mitigation Plan (WP02016-00009) —NA Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to discuss this review. Process: After plan revisions are reviewed and accepted, Deed of Dedication (with easement plat) for new SWM grass swales #1 and #2 must be recorded prior to VSMP plan approval. Plats require separate CDD Application, and review and approval process. Also, please contact Ana Kilmer, County Management Analyst, to inquire whether existing SWM Maintenance Agreement requires revision to cover new SWM facilities (grass swales #1, #2). Ana may be reached at 434.296-5832—x3246, or akilmeraalbemarle.org. Please feel free to call if any questions. Thank you. 434.296-5832 —x3069 WP0201300032 Cascadia blocks 4-7 VSMP Amendment 100218rcv3