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Home My WebLink AboutWPO201600031 Review Comments WPO VSMP 2020-04-23COUNTY 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 Amendment Review Project title: Whittington-Ph.B - VSMP — Amendment 2 Project file number: WP02016-00031 Plan preparer: Dustin Greene, EIT—Roudabush, Gale & Associates [dgreene(&,roudabush.com] 172 S. Pantops Drive, Charlottesville, VA 22911 Owner or rep.: Jeremy Swink, Stanley Martin Homes — 404 People Place, Suite 303 Charlottesville, VA 22911 (swinkjw@stanleymartin.com ) Plan received date: 26 Jul 2019 (Rev. 1) 5 Nov 2019 (Rev. 2) 13 Mar 2020 Date of comments: 29 Aug 2019 (Rev. 1) 6 Dec 2019 (Rev. 2) 23 Apr 2020 Reviewer: J. Anderson A. Stormwater Pollution Prevention Plan (SWPPP) —Update SWPPP (Rev. 2) Addressed. 2019 VPDES VAR10 Permit Registration Statement updated. [email, Dustin Greene, April 22, 2020 11:31 AM] B. 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. 1. Amendment appears to propose eliminating SWM9 and SWM10. Confirm that this is the case. (Rev. 1) Addressed. 2. If so, please confirm proposed Amendment increases total phosphorous load from 19.73 to 19.91 lb., and provide rationale, both for Amendment request (which appears unrelated to development area classification), and statutory basis to approve; that is, consider, outline and support path to approval for Amendment request to eliminate approved SWM facilities. (Engineering sees no rationale at the moment.) (Rev. 1) Addressed. As follow-up: provide photo image on plans showing — 20,000 SF of woods on Lots 70 and 71 that will be preserved by not constructing SWM9 and SWM10. Feel free to use images, below (sample images removed with Rev. 2 comments), which approximate locations of SWM9 / SWM10. (Rev.2) Addressed. Ref. 17 Feb 2020 RGA comment response letter, p. 5, e-attachment, April 22, 2020 11:31 AM (image below). [17-Feb 2020 RGA letter] Engineering Review Comments Page 2 of 4 County GIS (Lots 7071) (removed with Rev. 2 comments) Pietomeir-y/ satellite ifgay (3,110 2019) (removed with Rev. 2 comments) 3. Provide calculations, VaRRM.Xls, etc. that are basis of phosphorus load values on sheet 2. Do not simply reference WP0201600031. Engineering requests a complete submittal with details sufficient to outline proposed Amendment. Engineering cannot `fill in the blanks,' or guess at design intent, or commit time to research request to eliminate SWM9 and SWM10. No narrative is provided to support this Amendment request (no letter, no title sheet narrative —there are significant gaps with Amendment 2 request). (Rev. 1) Addressed. 4. Provide Narrative explaining /supporting: (Rev. 2) Addressed pending response to email request for copy of DEQ New Development VaRRM.xIs re£ on sheet 39 and sheet 1. The .xls will show that 1.00 Ac. Forest /Open Space (any soil type) is more than sufficient to offset 0.18 lb/yr TP removal provided by SWM9 and SWM10. SWM9 /SWM10 are not needed for phosphorus removal if 1.00 Ac. (any soil type) is placed in Forest /Open Space Easement providing 0.30 — 0.36 lb/yr. TP removal (reduction varies with soil type: A - type soils provide max [0.36 lb/yr], D soils, least [0.30 lb/yr]). [ 1.00 Ac. Forest /Open Space Easement plat, SUB202000052 is under review. 4/18/20 Engineering review comments request minor revisions to easement plat.] Applicant (April 23, 2020 letter /email April 22, 2020 11:31 AM): RESPONSE: See narrative on the cover sheet. The water quantity calculations have not changed from the original plans, to amendment #1 and to amendment #2. On 2/13/20 I met with John Anderson and Frank Pohl to talk about the discrepancy of the originally approved calculations and the routed calculations on the plans. Originally SWM #8 routed the 2yr and ioyr storms. The final plan which ended up being the originally approved plan used a splitter structure so that only the iyr storms went to the biofilter. This resulted in the 2yr and ioyr storms flowing to SWM #8 being undetained. The original, approved calculations show SWM #8 as detaining the 2yr and ioyr storms while the routed calculations on the approved plans show the SWM #8 as undetained. It was determined that the calculation packet did not need to be updated as the plans themselves show the correct flow numbers. I have provided the discrepancy in calculations for clarity. The county had asked me to demonstrate a `no effect' in water quantity from the original approved plan through both amendments so I started from the calculations and moved forward through the amendments and found this error in the original calculations. a. Eliminating approved SWM facilities. Engineering Review Comments Page 3 of 4 b. Elimination in context of calculations. c. Elimination in context of code /VAC. d. Include Narrative for Amendment 2 similar to 4-20-16 Sheet 1 Narrative for Amendment 1. (Rev. 1) Partially addressed. As follow-up: Cloud revision, 1111119 VSMP Amendment Narrative 31 sentence (sheet 1) reads: `The biofilters were not used for water quantity in order to satisfy channel and flood protection.' Furnish graphic (plan sheet) and additional narrative to tie Amendment 2 to approved Amendment 1 to illustrate `No effect' on post -developed approved runoff release rates; specifically, provide: Amendment 1 design event velocity /volume runoff rates; rates if SWM9 and SWM10 are replaced with 1.000 Ac. Forest /Open Space Easement (assume rates identical); and corresponding graphic plan information that makes the point. Reprint /include sheets as needed from WPO201600031 (or Amendment 1) to demonstrate no e ect on water quantity. 5. Clarify plan set, beginning with title. At first glance, reviewer and other staff mistook plan as initial Amendment. It is not. Sheet 1 Amendment Note for Amendment approved 7/7/16 should figure less prominently. Revise plan title to `Amendment 2 for Erosion & Sediment Control and Stormwater Management Plan for Whittington Subdivision -Phase B, WP0201600031. Approved Amendment 1 (9- sheet plan set; much more detail) is available at: https:Hlfweb. albemarle. org/weblink/search. aspx?dbid=3 &searchcommand=%7b%SbCDD - Planning%5d:%5bApplicationNumber%5d=%22WPO201600031%22%7d (Rev. 1) Not Addressed. belowimage (removed with Rev. 2 comments) is Sheet 1 of 9-p. Amendment approved 7/7/16. Please revise current submittal plan title to ref. Amendment 2 (see initial review comment; please call if questions). (Rev. 2) Addressed. 6. Include with Amendment 2 approved design data for SWM9 and SWM10. (Rev. 1) Addressed. 7. Include revised post -developed grades, if approved SWM facilities are eliminated. (Rev. 1) Withdrawn. 8. If review comments miss the mark, recommend meeting 16-Sep, 2PM. Reviewer is out of office thru 16- Sep, and welcomes meeting to discuss Amendment 2 at earliest convenience. (Rev. 1) Note: Applicant and County met to discuss. (Rev. 2) Note: County and Applicant met 2/13/20 to discuss project; several questions resolved. New: 9. Sheet 3 of Amendment (39 of WP0201600031): Show 1.000 Ac. Forest /Open Space Easement on this sheet. Label casement. (Rev. 2) Addressed. See sheet 39. 10. Provide 1" =50' (or similar) plan view of SWM9 and SWM10. Since these SWM Facilities are proposed to be removed, it is important to show approved design with the amendment that removes them. Details of these best management practices are indiscernible at 1" 200' scale (sheet 39). (Rev. 2) Addressed. See sheet 28. 11. Pending Forest /Open Space Easement Plat submittal: Include ties to two (2) permanent monuments. Additional Easement Plat review comments are possible. (Rev. 2) Persists /in process at SUB202000052; ref. 4/18/20 Engineering review comments. C. Erosion and Sediment Control Plan (ESOP) — NA D. Pollution Prevention Plan (PPP) NA The VSMP Amendment 2 (WP0201600031) may be approved once 1.00 Ac. Forest /Open Space Easement Plat is recorded and Albemarle receives response to email (April 23, 2020 3:21 PM) request for DEQ VaRRM.xls /New Development, and plan sheet revisions. Process: Prior to Amendment 2 approval, (SWM) Forest /Open Space Easement Plat must be approved /recorded. Please see email sent to Applicant, 12/6/2019 3:43 PM. A Maintenance Agreement is required for Forest /Open Space Easements. Contact Ana Kilmer at 434.296-5832 - x3246 to request Maintenance Agreement for WP0201600031, Amendment 2. Engineering Review Comments Page 4 of 4 Note: DEQ VPDES VAR 10 permit forms (2019 VPDES VAR10 Permit Registration form submitted, acceptable) may be required since permitted facilities will not be constructed with this Amendment. WPO Plan bond is not required. Applicant may request SWM Plan bond reduction since SWM9 and SWM10 will not be constructed, a reduction corresponding with SWM Plan bond expense assigned to these 2 facilities (once Amendment 2 is approved). County forms can be found on the county website forms center under engineering; hgp://www.albemarle.ora/dotforms.asp?department--cdenMo WP0201600031 Whittington Ph-B, VSMP Amend2 042320rev2