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Home My WebLink AboutSW4200703_17-101-SuppEZ-_20200708SUPPLEMENT-EZ COVER PAGE FORMS LOADED (PROJECT INFORMATION 1 JProject Name Project Area (ac) Hawbrid a School - New Upper School 2 7.56 3 Coastal Wetland Area (ac) 0 4 Surface Water Area (ac) 0.21 5 Is this project High or Low Density? High 6 Does this project use an off -site SCM? No �OOMPLIANCE WITH 02H .11003(4) 7 'Width of vegetated setbacks 2rovided (feet) 50 8 Will the vegetated setback remain vegetated? Yes 9 Is BUA other that as listed in .1003(4)(c-d) out of the setback? Yes 10 Is streambank stabilization proposed on this project? No INUMBER AND TYPE OF SCMs: 11 Infiltration System 0 1 12 Bioretention Cell 13 Wet Pond 0 14 Stormwater Wetland 1 15 Permeable Pavement 0 16 Sand Filter 0 17 1 Rainwater Harvesting (RWH) 0 18 (Green Roof 0 2 19 ILevel Spreader -Filter Strip (LS-FS) 20 Disconnected Impervious Surface (DIS) 0 21 Treatment Swale 0 22 Dry Pond 0 23 iStormFilter 0 24 Silva Cell 0 25 _ Bayfilter 0 26 Filterra 0 FORMS LOADED DESIGNER CERTIFICATION 27 Name and Title: Kenneth A Loring PE,PLS 28 Organization: CLH Design PA 29 ;Street address: 400 Regency Forest Dr, Suite 120 30 City, State, Zip: Cary, NC 27518 31 iPhone number(s): 919-319-6716 32 (Email: kloring@clhdesignpa.com r ifi t: 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 [he 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 r� SEAL _ 23953 '''H�i A.1.••. Seal Signature of Designer 7-- 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 SCM 1 Wetland SCM 2 Bio-Ret 5 Total BUA in project (sq ft 118701 sf 63735 sf 54966 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 118701 sf 63735 sf 54966 sf 8 Offsite - total area (sq ft) sf sf 16457 sf 9 Offsite BUA (sq ft sf sf 16457 sf 10 Breakdown of new BUA outside subdivided lots: Parking (sq ft 49137 sf 25251 sf 23886 sf Sidewalk (sq ft) 9322 sf 5396 sf 3926 sf Roof (sq ft 30204 sf 22331 sf 7872 sf Roadway (sq ft) sf sf sf Future (sq ft 10855 sf 8242 sf 2613 sf Other, please specify in the comment box below (sq ft) 2727 sf 2515 sf 212 sf 11 New infiltrating permeable pavement on subdivided lots (sq ft sf sf sf 12 New infiltrating permeable pavement outside of subdivided lots (sq ft) sf sf sf 13 Exisitng BUA that will remain (not subject to ermitting) (sq ft sf sf sf 14 Existing BUA that is already permitted (sq ft) sf sf sf 15 Existing BUA that will be removed (sq ft sf sf sf 16 Percent BUA 35% 51% 76% 17 Design storm inches N/A 1 in 1 in 18 Design volume of SCM (cu ft) N/A 5300 cf 4408 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 pavement pads for mechanical equipment and dumpsters; in -lieu of aquiring an agreement with offsite parcels for future BUA, we have allotted 100% of the offsite (0.38 ac - 16457 sf) to be impervious, this area has been added to the 'offsite" BUA section of the Bio- BIORETENTION CELL 1 1Drainage area number 2 2 IDesign volume of SCM (cu ft) 4408 cf 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 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 BIORETENTION CELL MDC FROM 02H .1052 18 SHWT elevation (fmsl) 458.00 19 Bottom of the bioretention cell (fmsl) 466.50 20 Ponding depth of the design storm (inches) 12 in 21 Surface area of the bioretention cell (square feet) 4430 sf 22 Design volume of the bioretention cell (cubic feet) 4408 cf 23 Is the bioretention cell used for peak attenuation? Yes 24 Depth of peak attenuation over planting surface (in) 13 in 25 Height of peak attenuation outlet above the planting surface (in) 12 in 26 Infiltration rate of the in situ soil (inch/hour) 1 in/hr 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) 468.5 30 Elevation of the planting surface (fmsl) 470 31 jWhat type of vegetation will be planted? (grass, trees/shrubs, other)? Grass 32 Media depth (inches) 42 in 33 Percentage of medium to coarse washed sand by volume 75-85 34 Percentage of fines (silt and clay) by volume 8%-10% 35 Percentage of organic matter by volume 5%-10% 36 Type of organic material Sod 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) N/A 41 Type of mulch, if applicable N/A 42 How many clean out pipes are being installed? 6 43 Type of pretreatment that will be used: ADDITIONAL INFORMATION Please use this space to provide any additional information about the 44 bioretention cell(s): Forebay �J Bioretention 3 1:35 PM 6/30/2020 STORMWATER WETLAND 1 1Drainage area number 1 2 IDesign volume of SCM (cu ft) 5300 cf GENERAL MDC FROM 02H .1050 3 1 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 Does the SCM have retaining walls, gabion walls or other engineered side 6 slopes? No Are the inlets, outlets, and receiving stream protected from erosion (10-year 7 storm)? Yes Is there an overflow or bypass for inflow volume in excess of the design 8 volume? Yes out 11 1 Does the maintenance access comply with General MUG (ay? Yes 12 Does the drainage easement comply with General MDC (9)? Yes If the SCM is on a single family lot, does (will?) the plat comply with General 13 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 STORMWATFR WETLAND MDC FROM 02H .1054 18 Are the inlet(s) and outlet located in a manner that avoids short-circuiting? Yes 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) 465.24 Elevation, temporary pool (top of the temporary inundation zone) (fmsl) 464.98 Elevation, permanent pool (top of the shallow water zone) (fmsl) 464.00 Elevation, bottom of shallow water zone (fmsl) 463.25 Elevation, bottom of forebay deep pool at deepest point (at forebay entrance) (fmsl) 460.00 Elevation, bottom of forebay deep pool at shallowest point (at forebay exit) (fmsl) 460.50 Elevation, bottom of non-forebay deep pool at deepest point (fmsl) 461.00 pinnr:nn 7nnnc 30 Area, total surface area of the SW wetland at temporary pool elev. (sq ft) 6,323.00 31 Area, temporary inundation zone at temporary pool elev. (sq ft) 2,743.00 32 Area, shallow water zone at temporary pool elev. (sq ft) 2,312.00 33 Area, forebayat temporary ool elev. (sq ft 765.00 34 Area, non-forebay deep pool at temporary ool elev .(sq ft 503.00 35 Percent area provided, temporary inundation zone should be 30-45 % 43% 36 Percent area provided, shallow water zone should be 35-45 % 37% 37 Percent areaprovided, deeppool (forebay)should be 10-15% 12% 38 Percent area provided, deep pool(non-forebay) should be 5-15 % 8% Depths and Outlet 39 40 41 42 43 44 45 46 47 48 Peak attenuation depth above temporary inundation zone (inches) 3 in �Temporary inundation zone depth (temporary ool to permanentpool) inches 12 in Shallow water one depth(permanent pool to bottom of wetland inches 9 in Depth, forebay at entrance (permanent pool to bottom of forebay entrance) inches 48 in Depth, forebay at exit(permanent pool to bottom of forebay exit inches 42 in Depth, non-forebay deep pools(permanent pool to deep pool bottom inches 36 in If there is an orifice, diameter inches 1 in If there is a weir, weir height inches N/A If there is a weir, weir length inches N/A Drawdown time for the temporary pool (days) 4.2 Snil end plenrc 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 1 Will cattails be planted in the wetland. o ADDITIONAL INFORMATION Please use this space to provide any additional information about the 56 stormwater wetland(s): Wetland 4 1:35 PM 6/30/2020 LEVEL SPREADER - FILTER STRIP (LS-FS 1 1 Drainage area number A B 2 IDesign volume of SCM (cu ft) N/A N/A GENERAL MDC FROM 02H .1050 3 Is the SCM sized to treat the SW from all surfaces at build -out? Yes Yes 4 Is the SCM located away from contaminated soils? Yes Yes 5 What are the side slopes of the SCM (H:V)? 3:1 3:1 6 Does the SCM have retaining walls, gabion walls or other engineered side slopes? No No 7 Are the inlets, outlets, and receiving stream protected from erosion (10-year storm)? Yes Yes 8 Is there an overflow or bypass for inflow volume in excess of the Idesign volume? Yes Yes 9 What is the method for dewatering the SCM for maintenance? Other Other 10 If applicable, will the SCM be cleaned out after construction? Yes Yes 11 Does the maintenance access comply with General MDC (8)? Yes Yes 12 Does the drainage easement comply with General MDC (9)? Yes Yes 13 If the SCM is on a single family lot, does (will?) the plat comply with General MDC (10)? No No 14 Is there an O&M Agreement that complies with General MDC (11)? Yes Yes 15 Is there an O&M Plan that complies with General MDC (12)? Yes Yes 16 Does the SCM follow the device specific MDC? Yes Yes 17 Was the SCM designedy an NC lic—e—ns-ed-p-rotessionalY Yes Yes JLS-FS MDC FROM 02H .1059 18 Length of level spreader (feet) 14 ft 16 ft 19 Does the LS-FS receive flow from the drainage area or another SCM? Drainage Area Drainage Area 20 Flow rate to LS-FS during design storm (cfs) 1.38 cfs 1.54 cfs 21 Is a bypass device provided? No No 22 If yes, what is the bypass device? N/A N/A 23 Is this LS-FS designed to receive flow from the drainage area during the 10-year storm? Yes Yes 24 Has a blind swale been provided? Yes Yes 25 Does the blind swale provide for uniform overtopping of the level spreader? Yes Yes 26 What material will be used for the level spreader? Concrete Concrete 27 Will the construction tolerance be < 0.25 inch along the level spreader length? Yes Yes 28 Will the level spreader be straight or convex in plan view? Straight Straight 29 Height of the drop from the level spreader to the transition zone (inches) 3 in 3 in 30 Width of the transition zone (inches) 72 in 72 in 31 Protection for the transition zone Other Other 32 Width of the filter strip (feet) 30 ft 30 ft 33 Is the filter strip free of draws and channels? Yes Yes 34 Has this been verified in the field? Yes Yes 35 Slope of the filter strip (%) 5% 5% 36 Is this slope uniform across the entire filter strip? Yes Yes 37 Will the first 12" of soil be adjusted if needed to promote plant growth? Yes Yes 38 Will the filter strip and side slopes be planted with non -clumping, deep-rooted sod? Yes Yes 39 Species of sod that will be used Bermuda Bermuda 40 Will soil be temporarily stabilized until permanent vegetation is established? Yes Yes ADDITIONAL INFORMATION 41 Please use this space to provide any additional information about the level spreader -filter strip(s): Line 31: Protection of the Transition Zone is 6" Thick Stone on Filter Fabric. - Line 2, LS-FS B design volume not coming from SCM. LS-FS 1 1:35 PM 6/30/2020