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Home My WebLink AboutWPO201900039 Review Comments Appeal to BOS 2020-09-04John Anderson From: John Anderson Sent: Friday, September 4, 2020 12:00 PM To: Seth Roderick Cc: Frank Pohl; Elam Summey; Lisa Perry, John Yerby; mmcginnis@r717.net; Tyler Jones Subject: RE: WPO 2019-00039 resubmittal package Seth, I realize Lisa is off, today. Albemarle is closed Monday ( holiday), so final revision /review /approval may need to wait till Tue, 8-Sep, or Wednesday. Review comments (plans d. 9/1/20): 1. Confirm if 1.63" orifice dimension at riser is accurate. 2. Provide inset small-scale plan /profile detail that illustrates how riser elements are arranged similar to 6'R basin 1 flow bypass structure, C-6.03R: a. Check 2" label against 1.63" label —are there two separate elements? If so, provide 1.63" orifice INV. If not, revise dimensions to match. Note: Albemarle does not typically approve orifice openings < 3" DIA. Very small orifices are prone to obstruction /SWM short-circuiting. b. Unclear how 1070.5' - 2" low flow orifice elevation works with bottom pool elev.=1071.00' ( plan /profile may help resolve). c. If weir plate is proposed interior to riser, show weir plate in plan /profile views. d. If weir plate is included with design, specify debris cage sized to prevent obstruction of 2" (or other small diameter) openings. e. Ensure small diameter openings are protected against obstruction from items that may pass openings in riser crest trash rack. f. Since height from riser floor to crest =57, show steps in plan view of riser, and ensure no conflicts with 18" pipe outfall. 3. Include riser trash rack detail , StormRaxTM for example: httos://www.conteches.com/stormwater- mana@ement/treatment/stormrax . 4. Include debris cage detail ( for small DIA orifices, interior to riser), as needed. 5. C-6.042, C-6.041R: Include Embankment Note 6 requiring PE -certification be submitted to Albemarle County attesting that `Items specified at Notes 1.-5. were met by and during construction.' 6. Include construction bullet point below from p. 17 of VA DEQ Stormwater Design Specification No. 2 on C-6.041R (basin # 1). • Construction of the gravel diaphragm or engineered level spreader shall not commence until the contributing drainage area has been stabilized and perimeter E&S controls have been removed and cleaned out. 7. Add note at ELS detail, C-6.041R blue circle, image below it., requiring each end of 56' ELS be embedded 2' in surrounding fill. Add note to construct a rising 4:1 slope (2: 1, max.), away from each end of embedded ELS to ensure concentrated flow does not cut a path around either end of the ELS. Additional detail re. this item: please see email sent August 28, 2020 1:25 PM. 8. Recommend label basin #2, C-6.03R. (unless it is labeled, and overlooked) 9. Provide note and detail for anchors for 18' — 15" CMP @ 33% ; ref. VDOT Drainage Manual, 9-37. 18" CMP WITH F.E.S. 60 FT ® 1.0% INV IN : 1070.40' INV OUT: 1069.80' CONCRETE FLOW BYPASS STRUCTURE 6' DIA. 4' HEIGHT RIM: 1072.10 RIF WE CREST: 1070.10 TO OF ;RETE GE - ON BASE CAI CO BO AT RISER FOR SIC & CLEANING 18 03 IN 0 ' C n L C \ INV OUT: 1063.00 VDOT Drainage Manual, 9.4.8.7 9.4A.7 Maximum Grades Slopes that incur uniform flow velocities in excess of 10 fps should be avoided because of the potential for abrasion. Slopes in excess of 16% are not preferred because of the need for anchor blocks. When anchor blocks are used, they should be installed at every other pipe joint, as a minimum. (See Special Design Drawing No. A-73 and MA- 73 for Anchor Details for Concrete Pipe) Corrugated pipe may be used on steep slopes in situations similar to those where shoulder slot inlets are proposed. Corrugated pipe should not be used in areas where the flow is expected to carry an abrasive bed load or that have PH and resistivity factors beyond the ranges specified in the Allowable Pipe Type Table C in Standard PC-1 of the VDOT Road and Bridge Standards. (See VDOT's Road and Bridge Standard PI-1, for Anchor Details for Corrugated Pipe) 10. Include VDOT 2016 R&B Anchor detail for CMP, PI-1 11. As follow -Lip to Item 2.e., email (August 21, 2020 6:05 PM); option a /b: a. Item 2.e. states: `Revise /amend WPO201900039 recently -amended ESC Plan to reflect measures required to construct detention basin'. Item 2.e. with this email is revised to read /require: `Provide note on SWM Plan Amendment to `Reference ESC Plan Amendment #2 for ESC plan measures relating to basin #2 construction." At this point, we leave it with Monteverde, but envision a straightforward single sheet Amendment #2 (WPO201900039 ESC Plan) that provides measures needed to construct basin #2, in phases (access/clear, construct, stabilize basin #2). A single sheet divided into quadrants might suffice; for example — quad/phase 1: access /clearing /perimeter measures; quad/phase 2: basin #2 construction; quad/phase 3: final stabilization; 4' quadrant, details /notes. OR b. Revise C-0.01 Note, last sentence, since next SWM plan sheet does present ESC measures. Reference ESC measures in revised C-0.01 Note. C-3.02-B: i. Include additional measures and/or sequencing notes that consider all aspects of basin #2 construction. ii. Provide corresponding measures, clearing thru final stabilization. iii. Label basin #2 construction access. iv. Provide construction entrance (CE) detail. v. Provide TS, PS, MU. vi. Note: With this option, Albemarle does not request Amendment to ESC Plan (Amendment #1), but would instead rely on SWMP, and be guided by C-3.02B. 12. As follow-np to email (August 28, 2020 10:45 AM, J. Anderson to Lisa Perry, Monteverde), and as follow-up to conversation between Seth Roderick and County Engineer, please delete sentence, Calc. packet, p. i., that reads: `The slope below the level spreader will be mitigated with earthen berms for 65'.' This statement appears unnecessary given conversation with Albemarle County Engineer, and assurance that vineyards are planted below basin # 1. Please delete stated reference to earthen berms, since request for downslope earthen berms is withdrawn at this time. (Also: email, F. Pohl to J. Anderson, September 2, 2020 9:38 AM. Also, Monteverde comment response letter, 9/l/20, p. 5, referencing discussion with Albemarle County Engineer on 9/1.) Note: Photos taken by inspector (attached to email 8/28/2020 10:09 AM) do not (appear to) indicate vineyards below basin # 1. For this reason, vineyard planting assumed to have occurred between time photos taken and discussion with county engineer Sep-L 13. C-6.03R: Label basin #2 SWM facility access. 14. C-6.03R: Add note that `Existing permanent fill diversion is installed and was observed to be adequate during site visit on 6/27/2020 by Monteverde design professional.' 15. C-6.041R: If vineyards are planted below proposed ELS / basin #1 /Ex. SB, restore graphic image of vineyards (Typ.) below basin #1 (visible /shown with C-6.041R on 8/7/20 plan), to indicate vineyards exist. ERFORATED PVC WRAPPED IN #571 & NON -WOVEN GEOTEXTILE, CAP INAL END, MOUND ASSEMBLY WITHi #57 STONE 16" HIGH, 2' WIDE j _OW ORIFICE PLATE TO BE INSIDE ACCESSIBLE FOR MAINTENANCE / v AND CLEANING --% /\\ \ 3: s�aaALa�i�i1�tTS� ��s�� 17. C-6.03R; basin 1 flow bypass structure: Provide grate or similar at 15" pipe outlet across entire 15" DfA, since 6" riprap in 6' MH ring extends below 15" pipe IW, slightly. Design must prevent riprap dislodging /obstructing 15" pipe to ELS. 18. Aside from items above Monteverde need not consider prior email on topic of SWM Plan Amendment (sent August 28, 2020 1:25 PM; August 28, 2020 10:45 AM August 26, 2020 9:53 AM, or Friday, August 21, 2020 6:05 PM, for example). Thanks for your efforts. Please let me know the primary point of contact, going forward —Elam, Lisa, or you, Seth. Thanks, again —best, J. Anderson John E. Anderson, PE I Civil Engineer 11 Department of Community Development I County of Albemarle, Virginia 401 McIntire Road I Charlottesville, VA 22902 434.296.5832 eat. 3069 Additional C-6.041R 18" CMP OUT: 1070.40' 2" LOW FLOW ORIFl .50' EME 7.5" ORIFICE 1071.5�CRE RISER CREST: 1076.70' 76.70' TOP j 100YR POOL ELEV.:1077.91' 10YR POOL ELEV.: 1076.80' 2YR POOL ELEV.: 1074.52' 3:1 SIDE SLOPES BOTTOM POOL ELEV.: 1071.00' MINIMUM 18%18" #57 STONE WRAPPED WITH NON —WOVEN GEOTEXTILE AROUND 6" PERFORATED PVC PIPE MIN 20' LENGTH 3' WIDE FILTER LAYER FABRIC STONES I 6"x 6" ESS TREATED TIMBERS W/ #5 REBAR ►.. 6'X6'X78" CONCRETE ANTI -FLOATATION BASE 1.63" ORIFICE AT RISER FOR MAINTENANCE & CLEANING From: Seth Roderick <sroderick@monteverdedesigns.com> Sent: Tuesday, September 1, 2020 3:54 PM To: John Anderson <janderson2@albemarle.org> Cc: Frank Pohl <fpohl@albemarle.org>; Elam Summey <esummey@monteverdedesigns.com>; Lisa Perry <Iperry@monteverdedesigns.com>; John Yerby <jyerby@albemarle.org>; mmcginnis@r717.net; Tyler Jones 5 <tjones@r717.net> Subject: WPO 2019-00039 resubmittal package John, Resubmittal package for the Hillcrest Vineyard site can be downloaded at the link below: https://www.d ropbox.com/sh/gw380197 b57zyoe/AABddtoT6pnX W9egN DM WTa0ha?d I=0 As with previous submittals, Tyler will coordinate application and fee. Please let me know if you have any questions during review. Thanks, Seth Roderick, PE Managing Partner (c) (540) 820-0898 F''OOWI �p �onteveide Engineenng 8 Design Studio 250 E Elizabeth St, Ste 114 Harrisonburg, VA 22802 (540)228-0202 www.MonteverdeDesigEs.com