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Home My WebLink AboutPN74813 Parachute Rigging Facility - NCDEQ Bioretention Supplement Forms Parachute Rigging Facility Fort Bragg, Cumberland County, North Carolina Mason & Hanger Page - a.8 - APPENDIX H NCDEQ BIORETENTION CELL SUPPLEMENT FORMS BIORETENTION CELL1Drainage area number1Total coastal wetlands area (sq ft) sf - Parking / driveway (sq ft)52134 sfTotal surface water area (sq ft) sf - Sidewalk (sq ft)1850 sfTotal drainage area (sq ft)385720 sf - Roof (sq ft)56000 sfBUA associated with existing development (sq ft)40511 sf - Roadway (sq ft) sfProposed new BUA (sq ft)109984 sf - Other, please specify in the comment box below (sq ft) sfPercent BUA of drainage area29%Total BUA (sq ft)109984 sfDesign rainfall depth (in)1.0 inMinimum volume required (cu ft)4005 cfDesign volume of SCM (cu ft)5520 cf#1 Is the SCM sized to treat the SW from all surfaces at build-out?Yes#7 If applicable, with the SCM be cleaned out after construction?Yes#2 Is the SCM located on or near contaminated soils?No#8 Does the mainetenance access comply with General MDC (8)?Yes#3 What are the side slopes of the SCM (H:V)?3:1#9 Does the drainage easement comply with General MDC (9)?Yes#3 Does the SCM have retaining walls, gabion walls or other engineered side slopes? No#10 If the SCM is on a single family lot, does the plat comply with General MDC (10)?Yes#4 Are the inlets, outlets, and receiving stream protected from erosion (10-year storm)? Yes#11 Is there an O&M Agreement that complies with General MDC (11)?Yes#5 Is there a a bypass for flows in excess of the design flow?Yes#12 Is there an O&M Plan that complies with General MDC (12)?Yes#6 What is the method for dewatering the SCM for maintenance?Other#13 Was the SCM designed by an NC licensed professional?Yes#1 SHWT elevation (fmsl)248 ft #6 Percentage of medium to coarse washed sand by volume 85%#1 Bottom of the bioretention cell (fmsl)250 ft #6 Percentage of fines (silt and clay) by volume10%#1 Distance from bottom to SHWT (feet)2 ft #6 Percentage of organic matter by volume 5%#2 Surface area of the bioretention cell (square feet)7360 sf#6 Type of organic materialEngineered Fill#2 Design volume of the bioretention cell (cubic feet)5520 cf#7 Phosphorus Index (P-Index) of media (unitless) 10#2 Ponding depth of the design storm (inches)9 in#8 Will compaction be avoided during construction?Yes#3 Is the bioretention cell used for peak attenuation?No#9 Will cell be maintained to a one inch/hour standard?Yes#3 Depth of peak attenuation over planting surface (in) in #10 Describe the planting plan:#3 Height of peak attenuation outlet above the planting surface (in) in#4 Infiltration rate of the in situ soil (inch/hour).1 in/hr#4 Diameter of the underdrain pipes (if applicable)8 in#4 Does the design include Internal Water Storage (IWS)?Yes #11 Depth of mulch, if applicable (inches) in#4 if so, elevation of the top of the IWS (fmsl)252 ft #11 Type of mulch, if applicablena#4 Elevation of the planting surface (fmsl)256 ft #12 How many clean out pipes are being installed?10#5 Will the cell contain trees and shrubs?No#12 Briefly describe the pretreatment that will be used:#5 Media depth (inches)30 inSOF Parachute Rigging FacilityTHE DRAINAGE AREABIORETENTION CELL MDC FROM 02H .10522.0 feet of open graded aggregate being provided under engineered fill/media depth in order to provide additional storage volume within cell to meet requirements for EISA 438. The engineered fill will infiltrate at approximately 2in/hr (maintained at min 1in/hr), which will eliminate the surface ponded volume within 24 hours, to the storage within the IWS for ultimate infiltration. Additionally, behive grated catch basins are provided as first-line overflow, above required storage volume, but not for peak attenuation volume. Maximum depth of storage of cell to emergency overflow is 12". Emergency overflow weir designed for 100yr storm event. Project based entirely within Fort Bragg (US Gov't property). No easements required. User requires no hardwood mulch due to maintenance issues.Break down of BUA in the drainage area (both new and existing):COMPLIANCE WITH THE APPLICABLE STORMWATER PROGRAMStormwater program(s) that apply (please specify):EISA 438, ARMY LID, FORT BRAGG IDGGENERAL MDC FROM 02H .1050ADDITIONAL INFORMATIONPlease use this space to provide any additional information about this bioretention cell that you think is relevant to the review:Contractor to provide landscape establishment to achieve 100% coverage throughout site in 12 months. Sod is desired by the user for cell. User requires no hardwood mulch within cell.Minimum 3' sod strip. All outlet headwalls to cell have rip-rap outlet protection per NCDEQ requirements.Bioretention21:25 PM 3/29/2019 BIORETENTION CELLSOF Parachute Rigging Facility2Drainage area number2Total coastal wetlands area (sq ft) sf - Parking / driveway (sq ft)6356 sfTotal surface water area (sq ft) sf - Sidewalk (sq ft)1250 sfTotal drainage area (sq ft)128938 sf - Roof (sq ft)29420 sfBUA associated with existing development (sq ft)5663 sf - Roadway (sq ft) sfProposed new BUA (sq ft)37026 sf - Other, please specify in the comment box below (sq ft) sfPercent BUA of drainage area29%Total BUA (sq ft)37026 sfDesign rainfall depth (in)1.0 inMinimum volume required (cu ft)2067 cfDesign volume of SCM (cu ft)3750 cf#1 Is the SCM sized to treat the SW from all surfaces at build-out?Yes#7 If applicable, with the SCM be cleaned out after construction?Yes#2 Is the SCM located on or near contaminated soils?No#8 Does the mainetenance access comply with General MDC (8)?Yes#3 What are the side slopes of the SCM (H:V)?3:1#9 Does the drainage easement comply with General MDC (9)?Yes#3 Does the SCM have retaining walls, gabion walls or other engineered side slopes? No#10 If the SCM is on a single family lot, does the plat comply with General MDC (10)?Yes#4 Are the inlets, outlets, and receiving stream protected from erosion (10-year storm)? Yes#11 Is there an O&M Agreement that complies with General MDC (11)?Yes#5 Is there a a bypass for flows in excess of the design flow?Yes#12 Is there an O&M Plan that complies with General MDC (12)?Yes#6 What is the method for dewatering the SCM for maintenance?Other#13 Was the SCM designed by an NC licensed professional?Yes#1 SHWT elevation (fmsl)249 ft #6 Percentage of medium to coarse washed sand by volume 85%#1 Bottom of the bioretention cell (fmsl)254 ft #6 Percentage of fines (silt and clay) by volume10%#1 Distance from bottom to SHWT (feet)5 ft #6 Percentage of organic matter by volume 5%#2 Surface area of the bioretention cell (square feet)5000 sf#6 Type of organic materialEngineered Fill#2 Design volume of the bioretention cell (cubic feet)3750 cf#7 Phosphorus Index (P-Index) of media (unitless) 10#2 Ponding depth of the design storm (inches)9 in#8 Will compaction be avoided during construction?Yes#3 Is the bioretention cell used for peak attenuation?No#9 Will cell be maintained to a one inch/hour standard?Yes#3 Depth of peak attenuation over planting surface (in) in #10 Describe the planting plan:#3 Height of peak attenuation outlet above the planting surface (in) in#4 Infiltration rate of the in situ soil (inch/hour).1 in/hr#4 Diameter of the underdrain pipes (if applicable)8 in#4 Does the design include Internal Water Storage (IWS)?Yes #11 Depth of mulch, if applicable (inches) in#4 if so, elevation of the top of the IWS (fmsl)256 ft #11 Type of mulch, if applicablena#4 Elevation of the planting surface (fmsl)260 ft #12 How many clean out pipes are being installed?5#5 Will the cell contain trees and shrubs?No#12 Briefly describe the pretreatment that will be used:#5 Media depth (inches)30 in2.0 feet of open graded aggregate being provided under engineered fill/media depth in order to provide additional storage volume within cell to meet requirements for EISA 438. The engineered fill will infiltrate at approximately 2in/hr (maintained at min 1in/hr), which will eliminate the surface ponded volume within 24 hours, to the storage within the IWS for ultimate infiltration. Additionally, behive grated catch basins are provided as first-line overflow, above required storage volume, but not for peak attenuation volume. Maximum depth of storage of cell to emergency overflow is 12". Emergency overflow weir designed for 100yr storm event. Project based entirely within Fort Bragg (US Gov't property). No easements required. User requires no hardwood mulch due to maintenance issues.GENERAL MDC FROM 02H .1050Contractor to provide landscape establishment to achieve 100% coverage throughout site in 12 months. Sod is desired by the user for cell. User requires no hardwood mulch within cell.Minimum 3' sod strip. All outlet headwalls to cell have rip-rap outlet protection per NCDEQ requirements.ADDITIONAL INFORMATIONTHE DRAINAGE AREABIORETENTION CELL MDC FROM 02H .1052Break down of BUA in the drainage area (both new and existing):COMPLIANCE WITH THE APPLICABLE STORMWATER PROGRAMStormwater program(s) that apply (please specify):EISA 438, ARMY LID, FORT BRAGG IDGPlease use this space to provide any additional information about this bioretention cell that you think is relevant to the review:Bioretention31:25 PM 3/29/2019 Discrete SCS Curve Number Method (NCDEQ Stormwater BMP Manual 3.3.2) Location:Bioretention Area 1 Date:3/28/2019 Soil Group:C Predevelopment BUA Developed BUA Area 0.93 acres Area 2.52 acres Area 40,511 sf Area 109,984 sf CN*98 CN*98 S 0.20 S 0.20 ia 0.04 in ia 0.04 in P 1 in P 1 in Q 0.79 in Q 0.79 in V 2,670 cf V 7,249 cf Predevelopment Open Area Developed Open Area Area 7.92 acres Area 6.33 acres Area 345,209 sf Area 275,736 sf CN*76 CN*74 S 3.16 S 3.51 ia 0.63 in ia 0.70 in P 1 in P 1 in Q 0.04 in Q 0.02 in V 1,107 cf V 533 cf Area 8.85 acres Area 8.85 acres Total 3,777 cf Total 7,782 cf Storage Required 4,005 cf Surface Area 7,360 sf Riser 9 in Storage Provided 5,520 cf Note: Runnoff depth for CN <= 70 set to 0.00 for 1.0" rainfall event based upon TR55 Urban Hydrology for Small Watersheds Table 2-1 *Composite CN calculated using Army LID Planning and Cost Tool Developed by USACE Baltimore District and USACE ERDC Discrete SCS Curve Number Method (NCDEQ Stormwater BMP Manual 3.3.2) Location:Bioretention Area 2 Date:1/7/2019 Soil Group:B Predevelopment BUA Developed BUA Area 0.13 acres Area 0.85 acres Area 5,663 sf Area 37,026 sf CN*98 CN*98 S 0.20 S 0.20 ia 0.04 in ia 0.04 in P 1 in P 1 in Q 0.79 in Q 0.79 in V 373 cf V 2,440 cf Predevelopment Open Area Developed Open Area Area 2.83 acres Area 2.11 acres Area 123,275 sf Area 91,912 sf CN*60 CN*61 S 6.67 S 6.39 ia 1.33 in ia 1.28 in P 1 in P 1 in Q 0.00 in Q 0.00 in V 0 cf V 0 cf Area 2.96 acres Area 2.96 acres Total 373 cf Total 2,440 cf Storage Required 2,067 cf Surface Area 5,000 sf Riser 9 in Storage Provided 3,750 cf Note: Runnoff depth for CN <= 70 set to 0.00 for 1.0" rainfall event based upon TR55 Urban Hydrology for Small Watersheds Table 2-1 *Composite CN calculated using Army LID Planning and Cost Tool Developed by USACE Baltimore District and USACE ERDC