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Stormwater Pipe_Verification Calcs_v.3 5.21.21
page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 1 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=5.37cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.70 acres Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. A1 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 15/13/20218:25 AM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 5.37 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=2 ft Q = flow rate (ft3 / s)=5.37 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.5 ft A = cross-sectional area of pipe (sf)=1.6sf Pw = Wetted Perimeter (ft)=3.1ft S = slope (ft / ft)=0.0101ft/ft QPIPE==12.3cfs Factor of Safety = QPIPE/Q25 =2.3 Velocity of pipes =3.4ft/s 6.0Conclusions/Results - Based on the calculations above, a 24" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 15/13/20218:25 AM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 2 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=1.82cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.30 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A2 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 25/13/20218:26 AM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 1.82 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=1.25 ft Q = flow rate (ft3 / s)=1.82 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.3 ft A = cross-sectional area of pipe (sf)=0.6sf Pw = Wetted Perimeter (ft)=2.0ft S = slope (ft / ft)=0.0236ft/ft QPIPE==5.4cfs Factor of Safety = QPIPE/Q25 =3.0 Velocity of pipes =3.0ft/s 6.0Conclusions/Results - Based on the calculations above, a 15" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 25/13/20218:26 AM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 3 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=7.19cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =1.00 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A1 + A2 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 35/12/20212:58 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 7.19 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=2 ft Q = flow rate (ft3 / s)=7.19 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.5 ft A = cross-sectional area of pipe (sf)=1.6sf Pw = Wetted Perimeter (ft)=3.1ft S = slope (ft / ft)=0.0178ft/ft QPIPE==16.4cfs Factor of Safety = QPIPE/Q25 =2.3 Velocity of pipes =4.6ft/s 6.0Conclusions/Results - Based on the calculations above, a 24" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 35/12/20212:58 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 4 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=4.63cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.60 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A3 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 45/12/20212:58 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 4.63 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=2 ft Q = flow rate (ft3 / s)=4.63 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.5 ft A = cross-sectional area of pipe (sf)=1.6sf Pw = Wetted Perimeter (ft)=3.1ft S = slope (ft / ft)=0.0119ft/ft QPIPE==13.4cfs Factor of Safety = QPIPE/Q25 =2.9 Velocity of pipes =2.9ft/s 6.0Conclusions/Results - Based on the calculations above, a 24" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 45/12/20212:58 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 5 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=0.79cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.10 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A6 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 55/12/20212:59 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 0.79 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=1.25 ft Q = flow rate (ft3 / s)=0.79 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.3 ft A = cross-sectional area of pipe (sf)=0.6sf Pw = Wetted Perimeter (ft)=2.0ft S = slope (ft / ft)=0.0129ft/ft QPIPE==4.0cfs Factor of Safety = QPIPE/Q25 =5.0 Velocity of pipes =1.3ft/s 6.0Conclusions/Results - Based on the calculations above, a 18" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 55/12/20212:59 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 6 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=1.58cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.20 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A5 + A6 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 65/12/20213:00 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 1.58 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=1.5 ft Q = flow rate (ft3 / s)=1.58 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.4 ft A = cross-sectional area of pipe (sf)=0.9sf Pw = Wetted Perimeter (ft)=2.4ft S = slope (ft / ft)=0.0129ft/ft QPIPE==6.5cfs Factor of Safety = QPIPE/Q25 =4.1 Velocity of pipes =1.8ft/s 6.0Conclusions/Results - Based on the calculations above, a 24" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 65/12/20213:00 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:RCP Culvert Sizing Pipe 7 1.0 Purpose/Objective - Size the RCP Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations RCP Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=9.31cfs RCP Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =1.20 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the RCP Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the RCP Culvert (Q25). A3 + A4 + A5 + A6 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 75/12/20213:01 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 9.31 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=3 ft Q = flow rate (ft3 / s)=9.31 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.013(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.8 ft A = cross-sectional area of pipe (sf)=3.5sf Pw = Wetted Perimeter (ft)=4.7ft S = slope (ft / ft)=0.0214ft/ft QPIPE==48.9cfs Factor of Safety = QPIPE/Q25 =5.3 Velocity of pipes =2.6ft/s 6.0Conclusions/Results - Based on the calculations above, a 36" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 75/12/20213:01 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 8 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=0.98cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.13 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A7 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 85/12/20213:01 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 0.98 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=1.25 ft Q = flow rate (ft3 / s)=0.98 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.3 ft A = cross-sectional area of pipe (sf)=0.6sf Pw = Wetted Perimeter (ft)=2.0ft S = slope (ft / ft)=0.0165ft/ft QPIPE==4.5cfs Factor of Safety = QPIPE/Q25 =4.6 Velocity of pipes =1.6ft/s 6.0Conclusions/Results - Based on the calculations above, a 18" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 85/12/20213:01 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:HDPE Culvert Sizing Pipe 9 1.0 Purpose/Objective - Size the HDPE Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations HDPE Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=3.29cfs HDPE Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =0.43 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the HDPE Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the HDPE Culvert (Q25). A7 + A8 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 95/12/20213:02 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILHDPE Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 3.29 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=1.5 ft Q = flow rate (ft3 / s)=3.29 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.012(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.4 ft A = cross-sectional area of pipe (sf)=0.9sf Pw = Wetted Perimeter (ft)=2.4ft S = slope (ft / ft)=0.017ft/ft QPIPE==7.4cfs Factor of Safety = QPIPE/Q25 =2.3 Velocity of pipes =3.7ft/s 6.0Conclusions/Results - Based on the calculations above, a 18" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 95/12/20213:02 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:RCP Culvert Sizing Pipe 10 1.0 Purpose/Objective - Size the RCP Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations RCP Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=18.76cfs RCP Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =3.12 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the RCP Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the RCP Culvert (Q25). A11 + A13 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 105/12/20213:02 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 18.76 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=3 ft Q = flow rate (ft3 / s)=18.76 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.013(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.8 ft A = cross-sectional area of pipe (sf)=3.5sf Pw = Wetted Perimeter (ft)=4.7ft S = slope (ft / ft)=0.02ft/ft QPIPE==47.3cfs Factor of Safety = QPIPE/Q25 =2.5 Velocity of pipes =5.3ft/s 6.0Conclusions/Results - Based on the calculations above, a 36" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 105/12/20213:02 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:RCP Culvert Sizing Pipe 11 1.0 Purpose/Objective - Size the RCP Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations RCP Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=32.51cfs RCP Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =5.42 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the RCP Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the RCP Culvert (Q25). A11 + A12 + A13 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 115/13/20218:29 AM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 32.51 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=3.5 ft Q = flow rate (ft3 / s)=32.51 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.013(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.9 ft A = cross-sectional area of pipe (sf)=4.8sf Pw = Wetted Perimeter (ft)=5.5ft S = slope (ft / ft)=0.0096ft/ft QPIPE==49.4cfs Factor of Safety = QPIPE/Q25 =1.5 Velocity of pipes =6.8ft/s 6.0Conclusions/Results - Based on the calculations above, a 42" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 115/13/20218:29 AM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:RCP Culvert Sizing Pipe 12 1.0 Purpose/Objective - Size the RCP Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations RCP Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=38.11cfs RCP Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =6.15 acres A7 + A8 + A9 + A11 + A12 + A13 - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the RCP Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the RCP Culvert (Q25). c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 125/12/20213:04 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 38.11 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=4 ft Q = flow rate (ft3 / s)=38.11 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.013(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=1.0 ft A = cross-sectional area of pipe (sf)=6.3sf Pw = Wetted Perimeter (ft)=6.3ft S = slope (ft / ft)=0.0134ft/ft QPIPE==83.4cfs Factor of Safety = QPIPE/Q25 =2.2 Velocity of pipes =6.1ft/s 6.0Conclusions/Results - Based on the calculations above, a 48" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 125/12/20213:04 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:RCP Culvert Sizing Pipe 13 1.0 Purpose/Objective - Size the RCP Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations RCP Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=38.80cfs RCP Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =6.24 acres A7 +A8 +A9 +A10 + A11 + A12 + A13 - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the RCP Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the RCP Culvert (Q25). c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 135/12/20213:05 PM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 38.8 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=4 ft elliptical pipe = 38"H x 60"W Q = flow rate (ft3 / s)=38.80 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.013(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.9 ft A = cross-sectional area of pipe (sf)=6.2sf Pw = Wetted Perimeter (ft)=6.5733ft S = slope (ft / ft)=0.0286ft/ft QPIPE==116.1cfs Factor of Safety = QPIPE/Q25 =3.0 Velocity of pipes =6.2ft/s 6.0Conclusions/Results - Based on the calculations above, a 48" diameter elliptical pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 135/12/20213:05 PM page 1 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Calculation Brief Title:RCP Culvert Sizing Pipe 14 1.0 Purpose/Objective - Size the RCP Culvert for the 25-year, 24-hour storm event. 2.0 Procedure 3.0References/Data Sources - Win TR-55 - FHWA Hydraulic Design of Highway Culverts - Publication No. FHWA - NHI - 01-020 (Sept 01) - Manning's Equation for Open Channel Flow 4.0Assumptions and Limitations - Select the 25-year, 24-hour storm event for New Hanover County, North Carolina - SCS Type II Hydrograph Formulation Applies - Vegetation is in good condition - Assume pipes are flowing half full 5.0Calculations RCP Culvert Flow Rate Task: The maximum design flow rate from the TR 55 Analysis. (Assume linear runoff function) Q25=32.51cfs RCP Culvert Size Verification Determine the largest contributing drainage area to any one inlet -Drainage Area =2.53 acres - Using TR-55 determine the peak flow for the 25-year, 24-hour storm event for the maximum contributing drainage to the culvert. - Design the RCP Pipe Culvert for the 25-year, 24-hour runoff from the maximum contributing drainage area. Determine the maximum runoff from the 25-year, 24-hour storm event for the RCP Culvert (Q25). A9 + A12 c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 145/13/20218:28 AM page 2 of 2 CLIENTNew Hanover County JOB NO.133920-237812COMPUTED BYBKW PROJECTConvenience Center Remodel DATE CHECKED1/16/2020 DATE12/29/2019 DETAILConcrete Pipe Culvert CHECKED BYM. BROKAW PAGE NO.1 of 2 Task: Use TR-55 method to determine the peak runoff for the 25-year, 24-hour storm event. Use 15.21 cfs Using Manning's equation and the assumed design slope and diameter determine pipe capacity. D= Diameter (ft)=3 ft Q = flow rate (ft3 / s)=15.21 cfs N = number of pipes=1 n = friction factor (dimensionless)=0.013(See Attachment 1) Rh = A/Pw = hydraulic radius (ft)=0.8 ft A = cross-sectional area of pipe (sf)=3.5sf Pw = Wetted Perimeter (ft)=4.7ft S = slope (ft / ft)=0.0092ft/ft QPIPE==32.1cfs Factor of Safety = QPIPE/Q25 =2.1 Velocity of pipes =4.3ft/s 6.0Conclusions/Results - Based on the calculations above, a 36" diameter pipe will provide adequate flow capacity to capture flow from the entire contributing drainage area. ASRnQh 213249.1= c:\pw_pl1\ryanka\d1941184\Stormwater Pipe_Verification Calcs_v.2.xlsxPipe 145/13/20218:28 AM ATTACHMENT NO. 1 FFE: 25.6 1 8 1 7 1 6 19 19 1 8 16 18 17 26 21 1 9 22 21 16 17 13 11 8 6 12 7 242322 19 17 12 2 0 15 10 10 15 10 15 10 20 25 2525 25 25 25 25 25 20 25 25 25 26 2 0 20 27 23 22 24 C100 OVERALL GRADING AND DRAINAGE PLAN R Know what's below. before you dig.Call NEW HANOVER COUNTY, NORTH CAROLINA NEW HANOVER COUNTY LANDFILL CONVENIENCE CENTER REDEVELOPMENT PROJECT © 2 0 2 1 NC F-1255 5400 Glenwood Avenue, Suite 400 Raleigh, NC 27612 | Tel: (919) 325-3500 ISSUE FOR BID N PLAN