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Home My WebLink AboutSW6231109_Design Calculations_20231127 Barker Laydown Yard Impervious Area Calculations Parcel Area 123.05 AC Total Surface Water Area 18.25 AC Total Project Area 4,565,088 SF 104.8 AC Ex.Impervious Area in Total Project Area (measured via aerial) Building 23,523 SF Total Ex.Impervious 23,523 SF Ex.Impervious Area Subject to Regulation `` \1j1111 i/,' 23,523 SF ��.�N CAR° Total Project Area "�•1• E$$ig`•41' 4,565,088 SF ••fib y.9•9 Temporary Impervious Area to be Installed — •Q SEAL r; = (Gravel Laydown Yard) 283,140 SF •• 055132 • — Temporary Impervious Area to be Removed ��fN tQ;•O (Gravel Laydown Yard) -283,140 SF //'9 G• . • • %. Future Impervious Area 0 SF /j�4;• RY A• ` — Total Proposed Impervious Area (Ex.Impervious Area Subject to Regulation+ lief/2 3 Proposed Impervious Area) 306,663 SF �% Total Proposed%Impervious (Total Proposed Impervious Area)/Total Project Area) 6.7 % Because Total Proposed%Impervious is less than 24%,development falls within the'Low Density'threshold. 1.„.1 pet PROJECT rijij�� DerJIeIry ® 50130756 Barker Laydown Yard �`, CLIENT Duke Energy Progress, LLC CALCULATION SHEET TITLE Rational Method Peak Flow Designer DM Reviewer DAR Sheet No. Date 9/13/2023 Date 9/13/2023 1 of 1 Post-Development Ditch 1 (PD1) Land Use Area(acres) C-Value Impervious 3.10 0.95 C-Values found using the Agricultural Land(Crop) 0.64 0.40 information provided by the NCDEQ. Cumulative 3.74 0.86 Intensity year= 3.91 in/hr Intensity25 year= 4.47 in/hr Peak 10-year Flow Q= 12.58 cfs Time of Concentration Peak 25-year Flow Assumed to be 30 minutes. Q= 14.38 cfs Intensity found from NOAA Atlas 14,Volume 2,Version 3 Channel/Swale Sizing Calculation 11/21/2023 Channel Type/Name: Temporary Diversion Ditch#1 User Input Data Project: Barker Laydown Yard(50130756) Calculated Value Location: Cumberland County,NC Reference Data Objective: Design channel to convey flow to existing storm system. References: (1)North Carolina Erosion and Sediment Control Planning and Design Manual (2)Elements of Urban Stormwater Design,H.R.Malcom. Procedure: Use procedures outlined in the above references.Rational Method will be used to calculate flows.Normal depth will be calculated using Mannings Equation.Water velocity will be calculated using the principle of continuity(Q= VA) Channels will be designed to carry flow generated by the 10-Year storm event using maximum slope. Calculations: Rational Method: Q=C*1*A Where Q=Flow(cfs) C=Runoff Coefficient Calculate'Weighted C'using Site Specific Data and Reference 2 I=Rainfall Intensity(in/hr) Find Intensity for 10-year event from A=Drainage Area lac) NOAA Precipitation Intensity Data Source C= 0.86 Ito=3.91 Use min.allowed to=30 min Drainage area(A)(ac)= 3.74 Q(cfs)= 12.58 Length(L)(ft)= 950 Calculations will be done using Manning's Equation to find normal depth Channel cross section and Continuity(Q=V`A)to find velocity. Q(ds)= 12.58 Sm„(ft/ft)=0.010 B(ft)= 6 ix. Milt). 3 Calculate normal depth and velocity with bare earth as lining From Ref.2,n= 0.020 Flow(cis)= 12.58 normal depth(ft)= 0.45 velocity(ft/s)= 3.84 Calculate normal depth and velocity with jute matting From Ref.2,n= 0.022 Flow(ds)= 12.58 normal depth(ft)= 0.47 velocity(ft/s)= 3.61 Calculate normal depth and velocity with straw w/net lining From Ref.2,n= 0.033 Flow(cis)= 12.58 normal depth(ft)= 0.59 velocity(ff/s)= 2.74 Calculate normal depth and velocity with grass as lining From Ref.2,n= 0.030 Flow(cis)= 12.58 normal depth(ft)= 0.56 velocity(ff/s)= 2.92 Calculate shear stress T=yds y=62.4 d=0.59 s=0.010 T=0.37 Maximum permissible shear stress for: Straw with net 1.45 Null Equation 3.6 gives the maximum shear stress in a bend. T.=Kcrc Calculate Shear Stress in Bend Rc= 5 T= 10 K,=2.00 Rd752 Rc/T= 0.5 / ` ` K,=2.38-0.206\ 4-0.0073rA 2<Ra<10 (3.7) Kb=2 K,=1.05 \ 10 z RdT Td @ Bend Slope= 1 Tb= where. R. =radius of curvature of the herd to the channel centeeine,m(ft) T =channel top(water surface)width,m(ft) 1 of 1.„.1 pet PROJECT rijij�� err ® 50130756 Barker Laydown Yard ��`, CLIENT Duke Energy Progress, LLC CALCULATION SHEET TITLE Rational Method Peak Flow Designer DM Reviewer DAR Sheet No. Date 9/13/2023 Date 9/13/2023 1 of 1 Post-Development Ditch 2(PD2) Land Use Area(acres) C-Value Impervious 2.51 0.95 C-Values found using the Agricultural Land(Crop) 0.49 0.40 information provided by the NCDEQ. Cumulative 3.00 0.86 Intensity year= 3.91 in/hr Intensity25 year= 4.47 in/hr Peak 10-year Flow Q= 10.09 cfs Time of Concentration Peak 25-year Flow Assumed to be 30 minutes. Q= 11.53 cfs Intensity found from NOAA Atlas 14,Volume 2,Version 3 Channel/Swale Sizing Calculation 11/21/2023 Channel Type/Name: Temporary Diversion Ditch#2 User Input Data Project: Barker Laydown Yard(50130756) Calculated Value Location: Cumberland County,NC Reference Data Objective: Design channel to convey flow to existing storm system. References: (1) North Carolina Erosion and Sediment Control Planning and Design Manual (2) Elements of Urban Stormwater Design,H.R.Malcom. Procedure: Use procedures outlined in the above references.Rational Method will be used to calculate flows.Normal depth will be calculated using Mannings Equation.Water velocity will be calculated using the principle of continuity(Q= VA) Channels will be designed to carry flow generated by the 10-Year storm event using maximum slope. Calculations: Rational Method: Q=C*I*A Where Q=Flow(cfs) C=Runoff Coefficient Calculate'Weighted C'using Site Specific Data and Reference 2 I=Rainfall Intensity(in/hr) Find Intensity for 10-year event from A=Drainage Area(ac) NOAA Precipitation Intensity Data Source C= 0.86 110=3.91 Use min.allowed to=30 min Drainage area(A)(ac)= 3.00 Q(cfs)= 10.09 Length(L)(ft)= 210 Calculations will be done using Manning's Equation to find normal depth Channel cross section and Continuity(Q=V*A)to find velocity. Q(cfs)= 10.09 Sr,,,(ft/ft)=0.010 B(ft)= 6 12- „,(4(- Calculate normal depth and velocity with bare earth as lining From Ref.2, n= 0.020 Flow(cfs)= 10.09 normal depth(ft)= 0.39 velocity(ft/s)= 3.57 Calculate normal depth and velocity with jute matting From Ref.2, n= 0.022 Flow(cfs)= 10.09 normal depth(ft)= 0.42 velocity(fds)= 3.35 Calculate normal depth and velocity with straw w/net lining From Ref.2, n= 0.033 Flow(cfs)= 10.09 normal depth(ft)= 0.52 velocity(ffs)= 2.55 Calculate normal depth and velocity with grass as lining From Ref.2, n= 0.030 Flow(cfs)= 10.09 normal depth(ft)= 0.50 velocity(ffs)= 2.72 Calculate shear stress T=yds y=62.4 d=0.52 s=0.010 T=0.33 Maximum permissible shear stress for: Straw with net 1.45 1 of 1