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Home My WebLink AboutSW1220301_Supplement-EZ Form_20220609DRAINAGE 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? No 4 If so, number of low density drainage areas 0 5 Is all/part of this project subject to previous rule versions? No FORMS LOADED DRAINAGE AREA INFORMATION Entire Site 1 4 Type of SCM Bioretention Bioretention 5 Total drainage area (sq ft) 74052 74052 6 Onsite drainage area (sq ft 74052 74052 7 Oftsite drainage area (sq ft) 0 0 8 Total BUA in project (sq ft 59548 sf 59548 sf 9 New BUA on subdivided lots (subject to permitting) (sq ft) 10permitting) New BUA not on subdivided lots (subject to sf 59548 sf 59548 sf 11 Offsite BUA (sq ft) 12 Breakdown of new BUA not on subdivided lots: Parking (sq ft 59548 sf 59548 sf Sidewalk (sq ft Roof (sq ft Roadway s ft Future (sq ft 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 ermitting) (sq ft 16 Existing BUA that is already permitted (sq ft 17 Existing BUA that will be removed (sq ft 18 Percent BUA 80% 80% 19 Design storm inches 1.0 in 1.0 in 20 Design volume of SCM cu ft 5812 cf 5812 cf 21 Calculation method for design volume Simple Method Simple Method ADDITIONAL INFORMATION 22 Please use this space to provide any additional information about the drainage area(s): This project is within Asheville Regional Airport property, which has a property area of 900ac. For the purposes of our calculations, the limits of our construction, 1.85 acres, was used when determining built upon area values. BIORETENTION CELL area Minimum required treatment volume ERAL 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 (110-yearstorm)? Yes 8 Is there an overflow or bypass for inflow volume in excess of the design volume? Yes g lWhat 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)? 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 6UM designedy an NC licensedprofessional? Yes BIORETENTION CELL MDC FROM 02H .1 552 18 SHWT elevation (fmsl) <2160.4 19 Bottom of the bioretention cell (fmsl) 2162.50 20 Ponding depth of the design storm (inches) 5 in 21 Surface area of the bioretention cell (square feet) 4861 sf 22 Design volume of SCM cu ft 5812 cf 23 Is the bioretention cell used for peak attenuation? Yes 24 Depth of peak attenuation over planting surface (in) 18 in 25 Height of peak attenuation outlet above the planting surface (in) 12 in 26 Infiltration rate of the in situ soil (inch/hour) N/A 27 Diameter of the underdrain pipes (if applicable) 4 in 28 Does the design include Internal Water Storage (IWS)? Yes 29 if so, elevation of the top of the IWS (fmsl) 2165 30 Elevation of the planting surface (fmsl) 2166.5 31 What type of vegetation will be planted? (grass, trees/shrubs, other)? Grass 32 Media depth (inches) 36 in 33 Percentage of medium to coarse washed sand by volume 75-85% 34 Percentage of fines (silt and clay) by volume 8-15% 35 Percentage of organic matter by volume 5-10% 36 Type of organic material Pine Bark Fines 37 Phosphorus Index (P-Index) of media (unitless) <30 38 Will compaction be avoided during construction? Yes 39 Will cell be maintained to a one inch/hour standard? Yes 40 Depth of mulch, if applicable (inches) Sod 41 Type of mulch, if applicable Sod 42 How many clean out pipes are being installed? 1 43 Type of pretreatment that will be used: Forebay ADDITIONAL INFORMATION 44 Please use this space to provide any additional information about the bioretention cell(s): (9) The method of dewatering the bioretention area is the outlet control structure. Bioretention 2 9:26 AM 6/6/2022