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Home My WebLink AboutSW3220202_Supplement-EZ Form_20221101SUPPLEMENT-EZ COVER PAGE FORMS LOADED PROJECT INFORMATION 1 Project Name 2 Project Area ac 3 Coastal Wetland Area WAXHAW TOWN CAMPUS 16.56 0 5 1 Is this project High or Low Density? Both High and Low Density 6 1 Does this protect use an off -site SCM? No COMPLIANCE WITH 02H .1003(4) 7 Width of vegetated setbacks provided (feet) 30 8 Will the vegetated setback remain vegetated? Yes 9 If BUA is proposed in the setback, does it meet NCAC 02H.1003(4)(c-d)? N/A 10 Is streambank stabilization proposed on this project? No NUMBER AND TYPE OF SCMs: 11 Infiltration System 12 Bioretention Cell 13 Wet Pond 14 Stormwater Wetland 15 Permeable Pavement 16 Sand Filter 1 17 Rainwater Harvesting (RWH) 18 Green Roof 19 Level Spreader -Filter Strip (LS-FS) 20 Disconnected Impervious Surface DIS 21 Treatment Swale 22 Dry Pond 23 StormFilter 24 Silva Cell 25 Bayfilter 26 Filterra FORMS LOADED SIGNER CERTIFICATION 27 Name and Title: Morgan Woolner, PE 28 Organization: Alfred Benesch & Company 29 Street address: 2359 Perimeter Pointe Parkway, Suite 350 30 City, State, Zip: Charlotte, NC 28208 31 Phone number(s): 704-521-9880 32 Email: MWoolner@Benesch.com Certification Statement: I certify, under penalty of law that this Supplement-EZ form and all supporting information were prepared under my direction or supervision, that the information provided in the form is, to the best of my knowledge and belief, true, accurate, and complete, and that the engineering plans, specifications, operation and maintenance agreements and other supporting information are consistent with the information provided here. Signature of Designer DRAINAGE AREAS 1 Is this a high density project? Yes 2 If so, number of drainage areas/SCMs 1 3 Does this project have low density areas? Yes 4 If so, number of low density drainage areas 1 5 Is all/part of this project subject to previous rule versions? No FORMS LOADED DRAINAGE AREA INFORMATION Entire Site 1 LD 1 4 Type of SCM Sand Filter 5 Total drainage area (sq ft 721354 315851 405,503 6 Onsite drainage area (sq ft 721354 315851 405503 7 Offsite drainage area (sq ft sf 0 0 8 Total BUA in project (sq ft 233291 sf 216699 sf 16592 sf 9 New BUA on subdivided lots (subject to permitting) 1 (sq ft) sf sf sf 10permitting) New BUA not on subdivided lots (subject to s Offsite BUA (sq ft) Breakdown of new BUA not on subdivided lots: Parking (sq ft) Sidewalk (sq ft 223319 sf 216699 sf 6620 sf 11 sf sf 12 127127 sf 127127 sf sf 15180 sf 15180 sf sf Roof (sq ft 34785 sf 30392 sf 4393 sf Roadway s ft 2227 sf sf 2227 sf Future (sq ft 44000 sf 44000 sf sf Other, please specify in the comment box below (sq ft 13 New infiltrating permeable pavement on subdivided lots (sq ft 14 New infiltrating permeable pavement not on subdivided lots (sq ft 15 Existing BUA that will remain (not subject to permitting) (sq ft) 9972 sf sf 9972 sf 16 Existina BUA that is already permitted (sq ft 17 Existing BUA that will be removed (sq ft) 18 Percent BUA 32% 69% 4% 19 Design storm inches 1 1.0 in 1.0 in 20 Design volume of SCM cu ft 13221 cf NA 21 Calculation method for design volume ADDITIONA NFORMATION 11111111F- Please use this space to provide any additional information about the 22 drainage area(s): Simple NA LOW DENSITY DESIGN REQUIREMENTS FOR LOW DENSITY PROJECTS FROM 02H .1003 1 Is project below density thresholds set forth in the applicable stormwater rule? Yes 2 Does project maximize dispersed flow and minimize channelization of flow? Yes 3 Has the use of piping been minimized per.1003(2)(c)? Yes 4 Side slopes of the vegetated conveyances (H:V) 31 5 Maximum velocity in the vegetated conveyances during the 10-year storm? 2 6 Are curb outlet swales proposed? No 7 Maximum longitudinal slope of curb outlet swale(s) (%) 8 Bottom width of curb outlet swale(s) (feet) 9 Maximum side slope of curb outlet swale(s) (H:V) 10 Minimum length of curb outlet swale(s) (feet) 11 Are treatment swales used instead of curb outlet swales? 12 Is stormwater released at the edge of the setback as dispersed flow? Yes 13 Have stormwater outlets been designed to prevent downslope erosion? Yes 14 lAre variations to rule .1003 proposed? No ADDITIONAL INFORMATION 15 Please use this space to provide any additional information about this low density project: Only 3 vegetated conveyances are proposed in the low density areas of the site. All are modifications of existing NCDOT swales carrying offsite runoff. The swales along Waxhaw Marvin Road will carry the project's proposed BUA that is not draining to the SCM Swale 4 FDrainage Area ac BUA (ac) Pervious area ac C Q (cfs) Slope ( % ) Va„ow (fps) Va ua (fps) Flow depth (ft) 1 0.52 0.33 0.19 0.71 2.81 5.60 5.00 4.24 0.47 2 0.48 0.27 0.21 0.67 2.42 4.10 5.50 3.65 0.47 3 0.67 0.38 0.29 0.67 3.39 7.20 5.00 4.90 0.48 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 SAND FILTER 1 Drainage area number 1 2 Minimum required treatment volume cu ft 13221 sf GENERAL MDC FROM 02H .1050 3 Is the SCM sized to treat the SW from all surfaces at build -out? Yes 4 Is the SCM located away from contaminated soils? Yes 5 What are the side slopes of the SCM (H:V)? 3:1 6 Does the SCM have retaining walls, gabion walls or other engineered side slo es? No 7 Are the inlets, outlets, and receiving stream protected from erosion (10-year storm)? Yes 8 Is there an overflow or bypass for inflow volume in excess of the design volume? Yes 9 What is the method for dewatering the SCM for maintenance? Pump (preferred) 10 If applicable, will the SCM be cleaned out after construction? Yes 11 Does the maintenance access comply with General MDC (8)? Yes 12 Does the drainage easement comply with General MDC (9)? Yes 13 If the SCM is on a single family lot, does (will?) the plat comply with General MDC (10)? N/A 14 Is there an O&M Agreement that complies with General MDC (11)? Yes 15 Is there an O&M Plan that complies with General MDC (12)? Yes 16 Does the SCM follow the device specific MDC? Yes 17 Was the SCM designed by an NC licensedprofessional? Yes SAND FILTER MDC FROM 02H .1056 18 SHWT elevation (fmsl) 501.5 19 Type of sand filter (open or closed) Open 20 If closed, will the filter will be pre -cast or pour -in -place? 21 If closed, top of grate elevation (fmsl) 22 Is this sand filter designed to attenuate peak flows? Yes Sediment Chamber 23 Volume that can be retained in the sediment chamber (cubic feet) 5722 cf 24 Will there be a permanent pool in the sediment chamber? No 25 Bottom of the sediment chamber (fmsl) 507.50 26 Area of the sediment chamber (square feet) 5798 sf 27 Physical depth of the sediment chamber (inches) 18 in 28 Ponding depth in the sediment chamber, above any permanent pool (inches) 18 in 291 Elevation of top of weir between chambers (fmsl) 509 I Sand Chamber 30 Volume that can be retained in the sand chamber (cubic feet) 8137 cf 31 Bottom of the sand chamber (fmsl) 507.00 32 Area of the sand chamber (square feet 4989 sf 33 Physical depth of the sand chamber (inches) 24 in 34 Ponding depth in the sand chamber, above the sand surface inches 24 in 35 Elevation of the bypass device (fmsl) 509 36 Type of bypass device OCS Weir 37 Mechanism for distributing flow over the sand surface Sheet flow 38 Sand specification for sand chamber CONCRETE SAND PER ASTM C-33 39 Depth above underdrain pipe (inches) 24 in 40 Will the media be maintained to drain at least two inches per hour at the sand surface? Yes L42 Is at least one clean -out pipe provided at the low point of each underdrain line? Yes Will clean -out pipes be capped? Yes INFORMATION I 43 Please use this space to provide any additional information about the I sand filter(s): Sand Filter 4 1:42 PM 9/23/2022