The URL can be used to link to this page

Home My WebLink AboutSW4191201_17-116 - SuppEZ_signed_5/18/2020SUPPLEMENT-EZ COVER PAGE FORMS LOADED (PROJECT INFORMATION 1 Project Name Lewisville Middle School 2 Project Area ac 66.21 3 Coastal Wetland Area ac 0 4 Surface Water Area ac 1.28 5 Is this project High or Low Density? High 6 Does this project use an off -site SCM? No COMPLIANCE WITH 021-11.1003(4) 7 Width of vegetated setbacks provided feet 30 8 Will the vegetated setback remain vegetated? Yes 9 Is BUA other that as listed in A 003 4 c-d out of the setback? Yes 10 Is streambank stabilization proposed on this project? Yes NUMBER AND TYPE OF SCMs: 11 Infiltration System Bioretention Cell 0 12 0 13 Wet Pond 1 14 Stormwater Wetland 1 15 Permeable Pavement 0 16 Sand Filter 0 17 Rainwater Harvestin RWH 0 18 Green Roof 0 19 Level Spreader -Filter Strip LS-FS) 0 20 Disconnected Impervious Surface (DIS) 0 21 1 Treatment Swale 0 22 Dry Pond 0 23 StormFilter 0 24 Silva Cell 0 25 Ba ilter 0 26 Filterra 0 FORMS LOADED DESIGNER CERTIFICATION 27 Name and Title: Kenneth Lorinq - Principal 28 Or anizatiom CLH Design PA 29 Street address: 400 Re2ency Forest Drive Suite 120 30 City, State, Zip* Cary. NC 31 Phone numbers : 919-319-6716 32 Email: 27518 Certification Staternenti 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. SEAL 23953 �.�c��.•.FNGrHEE�: Co: 1,4 ignature of Designer Date DRAINAGE AREAS 1 Is this a high density project? Yes 2 If so, number of drainage areas/SCMs 2 3 Is all/part of this project subject to previous rule versions? No FORMS LOADED DRAINAGE AREA INFORMATION Entire Site 1 2 4 Type of SCM N/A WET POND WETLAND 5 Total BUA in project (sq ft 401700 sf 368721 sf 32979 sf 6 New BUA on subdivided lots (subject to permitting) (sq ft) N/A N/A N/A 7permitting) New BUA outside of subdivided lots (subject to sf 378236 sf 345557 sf 32679 sf 8 Offsite - total area (sq ft) 0 19602 sf 0 9 Offsite BUA (sq ft 0 0 0 10 Breakdown of new BUA outside subdivided lots: Parking (sq ft 105490 sf 105490 sf 0 Sidewalk (sq ft) 25206 sf 23189 sf 2017 sf Roof (sq ft 58398 sf 58564 sf 0 Roadway (sq ft) 121582 sf 93234 sf 28348 sf Future (sq ft 30928 sf 28314 sf 2614 sf Other, please specify in the comment box below (sq ft) 29206 sf 36766 sf -300 sf 11 New infiltrating permeable pavement on subdivided lots (sq ft 0 0 0 12 New infiltrating permeable pavement outside of subdivided lots (sq ft) 0 0 0 13permitting) Exisitng BUA that will remain (not subject to s ft 30890 sf 23164 sf 300 sf 14 Existing BUA that is already permitted (sq ft) 0 0 0 15 Existing BUA that will be removed (sq ft 0 0 0 16 Percent BUA 14% 43% 37% 17 Design storm inches N/A 1 in 1 in 18 Design volume of SCM (cu ft) N/A 29521 cf 2822 cf 19 Calculation method for design volume N/A SIMPLE SIMPLE ADDITIONAL INFORMATION 20 Please use this space to provide any additional information about the ldrainage area(s): "Other" BUA includes gravel fire lane and "rock dust' track; in -lieu of aquiring an agreement with offsite parcels for future BUA, we have allotted 100% of the offsite (0.45 ac - 19602 sf) to be impervious, this area has been added to the "future" BUA section of the wet pond. WET POND 11 Drainage area number 1 2 Design volume of SCM (cu ft) 30991 cf GFNFRC. MnC FRC)M O)'H _7050 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 slopes? 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? Drawdown Orifice 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)? No 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 licensed professional? Yes WET POND MDC FROM 02H .1053 181 Method used HRT 19 Has a stage/storage table been provided in the calculations? Yes 20 Elevation of the excavated main pool depth (bottom of sediment removal) (fmsl) 822.50 21 Elevation of the main pool bottom -(top of sediment removal) (fmsl) 823.00 22 Elevation of the bottom of the vegetated shelf (fmsl) 826.00 23 Elevation of the permanent pool (fmsl) 826.50 241 Elevation of the top of the vegetated shelf (fmsl) 827.00 25 Elevation of the temporary pool (fmsl) 827.31 26 Surface area of the main permanent pool (square feet) 30040:1 27 Volume of the main permanent pool (cubic feet) 87015 cf 28 Average depth of the main pool (feet) 3.13 ft 29 Average depth equation used Equation 3 30 If using equation 3, main pool perimeter (feet) 796.0 ft 311 If using equation 3, width of submerged veg. shelf (feet) 3.0 ft 32 Volume of the forebay (cubic feet) 14313 cf 33 Is this 15-20% of the volume in the main pool? Yes 34 Clean -out depth for forebay (inches) 54 in 35 Design volume of SCM (cu ft) 30991 cf 36 Is the outlet an orifice or a weir? Orifice 37 If orifice, orifice diameter (inches) 2.5 381 If weir, weir height (inches) N/A 39 If weir, weir length (inches) N/A 40 Drawdown time for the temporary pool (days) 4.5 41 Are the inlet(s) and outlet located in a manner that avoids short- circuiting? Yes 42 Are berms or baffles provided to improve the flow path? No 43 Depth of forebay at entrance (inches) 66 in 441 Depth of forebay at exit (inches) 60 in 45 Does water flow out of the forebay in a non -erosive manner? Yes 46 Width of the vegetated shelf (feet) 6 ft 47 Slope of vegetated shelf (H:V) 6:1 48 Does the orifice drawdown from below the top surface of the permanent pool? Yes 49 Does the pond minimize impacts to the receiving channel from the 1- yr, 24-hr storm? Yes 50 Are fountains proposed? (If Y, please provide documentation that MDC(9) is met.) No 51 Is a trash rack or other device provided to protect the outlet system? Yes 52 Are the dam and embankment planted in non -clumping turf grass? Yes 53 Species of turf that will be used on the dam and embankment No Mow Seed Mix 54, Has a planting plan been provided or the vegetate shelf? es ADDITIONAL INFORMATION 55 Please use this space to provide any additional information about the wet pond(s): Wet Pond 3 3:42 PM 5/15/2020 STORMWATER WETLAND 1 Drainage area number 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 slopes? 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?\ Drawdown Orifice 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)? No 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 licensed professional? Yes WETLAND MDC FRIll Are the inlet(s) and outlet located in a manner that avoids short-circuiting? Yes STORMWATER 18 19 Are berms or baffles provided to improve the flow path? Yes 20 Does the orifice drawdown from below the top surface of the permanent pool? Yes 21 Does the wetland minimize impacts to the receiving channel from the 1-yr, 24- hr storm? Yes 22 Is a trash rack or other device provided to protect the outlet system? Yes Elevations 23 24 25 26 27 28 29 Elevation, peak attenuation above temporary pool (if applicable) (fmsl) 814.13 Elevation, temporary pool (top of the temporary inundation zone) (fmsl) 812.71 Elevation, permanent pool (top of the shallow water zone) (fmsl) 812.00 Elevation, bottom of shallow water zone (fmsl) 811.50 Elevation, bottom of forebay deep pool at deepest point (at forebay entrance) (fmsl) 809.00 Elevation, bottom of forebay deep pool at shallowest point (at forebay exit) (fmsl) 809.50 Elevation, bottom of non-forebay deep pool at deepest point (fmsl) 809.50 Planting Zones 30 Area, total surface area of the SW wetland at temporary pool elev. (sq ft) 4,234.00 31 Area, temporary inundation zone at temporary pool elev. (sq ft) 1,324.00 32 Area, shallow water zone at temporary pool elev. (sq ft) 1,690.00 33 Area, forebay at temporary pool elev. (sq ft) 630.00 34 Area, non-forebay deep pool at temporary pool elev .(sq ft) 590.00 35 Percent area provided, temporary inundation zone (should be 30-45%) 31 36 Percent area provided, shallow water zone (should be 35-45%) 40 37 1 Percent area provided, deep pool (forebay) (should be 10-15%) 15 38 1 Percent area provided, deep pool (non-forebay) (should be 5-15%) 14 (Depths and Outlet 39 40 41 42 43 44 45 46 47 48 Peak attenuation depth above temporary inundation zone (inches) 17.04 �Temporary inundation zone depth (temporary ool to permanentpool) (inches) 8.52 Shallow water zone depth(permanent pool to bottom of wetland inches 6 in Depth, forebay at entrance (permanent pool to bottom of forebay entrance) (inches) 36 in Depth, forebay at exit(permanent pool to bottom of forebay exit inches 30 in Depth, non-forebay deep pools(permanent pool to deep pool bottom inches 24 in If there is an orifice, diameter inches 1 in If there is a weir, weir height inches 12 in If there is a weir, weir length inches 12 in Drawdown time for the temporary pool (days) 2.6 Soil and Plants 49 Soil amendment depth (inches) 12 in 50 Has a soil amendment specification been provided? Yes 51 Has a landscaping plan that meets SW Wetland MDC (12) been provided? Yes 52 Number of plants per 200 square feet (#) in the shallow water zone: 50 53 Does the temporary inundation zone planting comply with SW Wetland MDC (14)? Yes 54 Are the dam structure and temporary fill slopes planted in non -clumping turfgrass? Yes 55 lWill cattails be planted in the wetland. No ADDITIONAL INFORMATION Please use this space to provide any additional information about the 56 stormwater wetland(s): Line 52, 50 plants for 200 SF in shallow water zone (line 52 will not let user type anything) Wetland 4 3:42 PM 5/15/2020