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Home My WebLink AboutWPO201600009 Bond Reduction 2022-04-29 (2)�q oe nt 401 McIntire Road, North Wing Charlottesville,VA22902-4579 County of Albemarle Telephone: 434-296-5832 COMMUNITY DEVELOPMENT DEPARTMENT WWW.ALBEMARLE.ORG VSMP Bond Inspection Letter Project title: Old Trail Village Block 10, 16, 17, 18, and 30* Stormwater Management Plan Project file number: WP0201600009 Owner or rep.: Dave Brockman [ dave@oldtrailvillage.com ] Inspection date: As -built review and 4-15-22 Mark Hopkins inspection Date of reduction: 28 Apr 2022 Reviewers: John Anderson, Emily Cox, Mark Hopkins Dear Mr. Brockman, We received your WPO bond inspection request for WP0201600009. The E&S bond can be reduced to $73,100(20% of the original bond). See attached spreadsheet for E&S. The SWM bond can be reduced to $187,912(40% of the original bond). The following items must be completed before the SWM bond can be further reduced or released: 1) Biofilter S-3: a. Ensure as -built riser rim is =0.5' higher than biofilter floor (both appear to be 658.50'). Riser must be 0.5' higher than floor to avoid short-circuiting of facility. b. Furnish evidence 20-ft. emergency spillway was constructed with 880 SF landlock 450 turf reinforcement matting, or equivalent, per approved plan. Rock armor tends to erode from beneath, unless underlayment is used, or stone is keyed into earth. c. Confirm that orifices are installed in detention riser. As -built states neither 10" nor 2-9" orifices were 'observed at time of survey.' Orifices are required. d. Confirm via as -built that upstream and downstream high flow channels are constructed per plan detail. The detail is specific, is shown in light line type on the As -built in design condition, but the as -built condition (plan view) appears to indicate mass stone placement that may not reflect detail, or ensure high -flow channel will function as designed. See Stantec approved plan, d. 6/28/16, sheet 4. e. Confirm embankment back -fill material consist of GC, SC, CL, CH, and/or MH soils. It was not evident in the F&R geotechnical report that was submitted. See Stantec 6/28/16 SWM plan, sheet 4, Note 1. f. Confirm /revise As -built to indicate signs every 150 along the perimeter of the facility. See Stantec 6/28/16 plan, sheet 4, Note 2. g. As -built should consider design elevation or design criteria labels, and report as -built condition for these items; for example: plunge pool lined with 14.1 CY Class Al riprap. 2) Biofilter S-12: a. Contours appear to indicate less (detention) volume than design. If detention volume is < design volume, evaluate effect on Q2,10 peak flow, via routing. Ensure detention outfall pipe capacity is sufficient for as -built volume detained, if detained (As -built) volume < design volume. b. As -built states several items not observed at time of survey; revise As -built to report values for these items, once items observed, if values are salient to facility performance. c. As -built label indicates detention outfall pipe end wall not installed. Install end wall per approved plan. (Design specified RCP /end wall -HDPE pipe is installed, without end wall) 3) 4) Engineering Review Comments Page 2 of 3 d. As -built contours do not tie to existing contours. It appears, for example, new contour 654 ties to contour 640. May correct by extending new contour (dash) line type further west. Revise As -built to show as -built /existing contours tie. I� I E REP _--___-- SENEREAS CM _ _ — -1 _ _ FMAW3 _ —=1_ _---- _ OB. 181B. FG .VJ e. Manmade detention outfall riprap channel does not extend to floodplain limit; extend to floodplain limit, per design. f. Revise As -built to reflect biofilter surface elevation and riser crest rim elevation (riser should be 0.5' higher than biofilter surface). g. Confirm 6" orifice at 639.57' v. 4" design orifice; confirm larger orifice diameter provides equivalent detention /does not affect routing. Provide calculations /hydroCAD routings. L-2, Retention basin III: a. As -built L-2 outfall appears to discharge to ACSA easement, not county drainage easement. If accurate, revise either as -built location of L-2 outfall riprap, or revise easement plat. If accurate, ACSA would likely object to one of several potential negative outcomes if SWM facility discharges to sanitary sewer corridor, above sanitary pipe. L-3, Enhanced extended detention pond a. Provide report /summary of geotechnical engineer -required test of low marsh design area L-3, Approved enhanced extended detention) for determining necessity of geosynthetic liner. (blue circle, Approved Amendment; image, below). sY PYo wEo mr at o —r N vISW J I Im}. FN aaFl - 6 70, 3 PFOEILE NP EtcY k 3]E� yY - PMMSEO H W TO WASH Y 3) R( AN=aN.0.11.Y � EN'a'NFP 91WL IaYE / RIWIINW 166SIM1? � / INYE W i -I - / FAP M NINCW➢ / — f - N.Y s i T y PIgRCTOX F \ N y, Faa� 4 PIWII OMmENSIONS Z ,,.�"'N1. Engineering Review Comments Page 3 of 3 b. Note: There did not appear to be any geotechnical reports for L-3 in the submitted geotechnical package. c. Revise As -built to include data, once observed in field, once sections of enhanced extended detention pond are not holding water, and features are visible /measurable. d. Provide As -built planting plan for comparison with sheet 7, WPO201600009 (Amendment) planting plan. As -built should confirm 20' landscape buffers, lap rail fence. 5) All SWM facilities: a. Compare As -built biofilter surface area (ft2) and retention basin III /enhanced extended detention pond volume (ft3) against design values. If as -built value is less than design, evaluate effect on stormwater quantity or quality control. b. Provide verified drainage area maps. c. SWM facility outfall pipes: provide pipe inspection video for all 4 facilities, including pipes that connect biofilters with stormwater detention, downstream. d. Approved WPO includes planting plans for each SWM facility. Provide as -built counts of plants, per type, per SWM facility. Replace any trees/shrubs that are unhealthy or have died. e. Ensure all plan /profile critical elevations are shown on As -built; for example, 5-12 biofilter floor and riser rim elevation. f. Ensure As -built linework overlays readable /legible design layer. Three of four as-builts do not display distinct design linework, making as -built v. design comparison difficult. g. Ensure all survey dates are accurate; for example: please revise survey date Dec 14, 2022 to read Dec 14, 2021. (Typo check) h. Revise As -built to confirm riser trash rack/s installed. Please see the following for Albemarle County Construction Record Drawings (As -built) requirements: httos://www.al bemarle.org/home/showpu bl isheddocument/212/637202327505370000 and https://library.municode.com/va/albemarle_county/codes/code_of_ord finances?nodeld=CH 17WAPR_ART IVPRSUREACAPPOPRRIOB DIV4POPRRIOB 517-422COREDRSU Please contact me if you have any questions. Sincerely, Emily Cox, PE (434) 296-5832 ext 3565 BOND ESTIMATE - EROSION CONTROL PROJECT NAME: Old Trail Village Blocks 10, 16, 17, 18, & 30 PROJECT NUMBER: 2016-00009 DATE OF ESTIMATE: 04/25/22 ESTIMATE BY: MRH BASED ON: WATER ITEM DESCRIPTION UNIT QUANTITY UNIT COST ITEM TOTAL SEED, FERTILIZE, MULCH ACRE 7 1500 10500 SILT FENCE LF 1000 9.5 9500 Tree Protection Fence LF 0 5 0 SAFETY FENCE LF 0 9.5 0 TEMPORARY FILL DIVERSION LF 0 3 0 DIVERSION DIKE LF 0 10 0 TEMPORARY SLOPE DRAIN LF 0 20 0 SEDIMENT TRAP 1 LS 0 0 0 SEDIMENT TRAP 2 LS 0 0 0 SEDIMENT TRAP 3 LS 0 0 0 SEDIMENT TRAP 4 LS 0 0 0 SEDIMENT TRAP 5 LS 0 0 0 SEDIMENT TRAP 6 LS 0 0 0 SEDIMENT TRAP 7 LS 0 0 0 SEDIMENT TRAP 8 LS 0 0 0 SEDIMENT TRAP 9 LS 0 0 0 SEDIMENT TRAP 10 LS 0 0 0 SEDIMENT TRAP 11 LS 0 0 0 SEDIMENT TRAP 12 LS 0 0 0 SEDIMENT TRAP 13 LS 0 0 0 SEDIMENT TRAP 14 LS 0 0 0 SEDIMENT TRAP 15 LS 0 0 0 SEDIMENT TRAP 16 LS 0 0 0 SEDIMENT TRAP 17 LS 0 0 0 SEDIMENT TRAP 18 LS 0 0 0 SEDIMENT BASIN 1 LS 0 0 0 SEDIMENT BASIN 2 LS 0 0 0 SEDIMENT BASIN 3 LS 0 0 0 SEDIMENT BASIN 4 LS 0 0 0 SEDIMENT BASIN 5 LS 0 0 0 SEDIMENT BASIN 6 LS 0 0 0 SEDIMENT BASIN 7 LS 0 0 0 SEDIMENT BASIN 8 LS 0 0 0 SEDIMENT BASIN 9 LS 0 0 0 SEDIMENT BASIN 10 LS 0 0 0 Stream Crossing Type 1-1 EA 0 1000 0 Stream Crossing Type 1-2 EA 0 1000 0 Stream Crossing Type 1-3 EA 0 1000 0 Stream Crossing Type 2-1 EA 0 3000 0 Stream Crossing Type 2-2 EA 0 3000 0 Stream Crossing Type 2-3 EA 0 3000 0 Stream Crossing Type 3-1 EA 0 5000 0 Stream Crossing Type 3-2 EA 0 5000 0 Stream Crossing Type 3-3 EA 0 5000 0 CULVERT INLET PROTECTION EA 0 500 0 INLET PROTECTION EA 10 200 2000 Drop Inlet Repair / Completion < 25 EA 0 1000 0 Drop Inlet Repair / Completion > 25 EA 0 500 0 OUTLET PROTECTION LS 0 14100 0 EC-2 & 3 DITCH PROTECTION LF 0 10 0 RIP -RAP LF 0 60 0 WEIRS IN SILT FENCE SQ.YD. 0 30 0 CHECK DAMS SQ.YD. 0 30 0 PAVED CONSTRUCTION ENTRANCE EA 0 3500 0 Mobilization LS 1 500 500 Surrvey & Layout LS 1 5000 5000 SUBTOTAL 27500.00 Contingency LS 10% 2750.00 Total LS 30250.00 ORIGINAL AMOUNT 365500 20% OF ORIGINAL 73100 73100.00 GREATER AMOUNT - 20% OR TOTAL BOND AMOUNT REQUIRED 73100.00