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Home My WebLink AboutSW3240204_Design Calculations_20240305 Appendix C Supporting Calculations NOAA Atlas 14 Precipitation Data Diversion Swale for Post Construction USGS StreamStats Peak Flow Culvert Calculations Riprap Outlet Protection Calculations NOAA Atlas 14 Precipitation Data NOAA Atlas 14,Volume 2,Version 3 Location name: Fairview,North Carolina,USA* Latitude:35.13050,Longitude:-80.49450 Elevation:514 ft** 'source:ESRI Mapvo source:USGS ""`" POINT PRECIPITATION FREQUENCY ESTIMATES G.M.Bonnin,D.Martin,B.Lin,T.Parzybok,M.Yekta,and D.Riley NOAA,National Weather Service,Silver Spring,Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90%confidence intervals (in inches/hour)1 Average recurrence interval(years) Duration�� 10 25 50 100 200 500 1000 5-min 4.98 5.88 6.84 7.52 8.30 8.84 9.32 9.76 10.2 10.6 (4.58-5.42) 11 (5.41-6.41) 1 (6.26-7.44) 11 (6.89-8.17) 1 (7.57-9.00) 11 (8.02-9.58) 11 (8.42-10.1) 1 (8.77-10.6) 11 (9.12-11.1) 1 (9.35-11.5) 10-min 3.98 4.70 5.47 6.02 6.61 7.04 7.41 7.73 8.09 8.32 (3.67-4.33) (4.33-5.13) (5.02-5.96) (5.51-6.53) (6.04-7.17) (6.39-7.63) (6.70-8.03) (6.95-8.39) (7.21-8.80) (7.36-9.06) 15-min 3.32 3.94 4.62 5.07 5.59 5.94 6.24 6.50 6.79 6.96(3.05-3.60) (3.62-4.30) (4.23-5.03) (4.64-5.51) (5.10-6.06) (5.39-6.44) (5.64-6.76) (5.84-7.05) (6.05-7.38) (6.16-7.58) 30-min 2.27 2.72 3.28 3.68 4.14 4.47 4.78 5.06 5.40 5.64 (2.09-2.47) (2.50-2.97) (3.01-3.57) (3.37-3.99) (3.78-4.49) (4.06-4.85) (4.32-5.18) (4.55-5.49) (4.81-5.87) (4.99-6.14) 60-min 1.42 1.71 2.10 2.39 2.76 3.03 3.29 3.55 3.88 4.12 (1.30-1.54) (1.57-1.86) (1.93-2.29) (2.19-2.60) (2.51-2.99) (2.75-3.29) (2.98-3.57) (3.19-3.85) (3.45-4.21) (3.64-4.48) 2-hr 0.820 0.992 1.23 1.41 1.64 1.82 1.99 2.17 2.39 2.56 (0.752-0.897) (0.908-1.09) 1 (1.12-1.35) 11 (1.29-1.54) 1 (1.49-1.79) 11 (1.64-1.98) 11 (1.79-2.17) 1 (1.93-2.36) (2.11-2.61) (2.24-2.80) 3-hr 0.581 0.701 0.876 1.01 1.19 1.33 1.48 1.62 1.82 1.98 (0.531-0.639) (0.642-0.771) (0.800-0.962) (0.920-1.11) 1 (1.08-1.30) 11 (1.20-1.45) 11 (1.32-1.61) 1 (1.44-1.77) 11 (1.59-1.98) 1 (1.71-2.16) 6-hr 0.351 0.423 0.528 0.611 0.722 0.811 0.902 0.995 1.12 1.22 (0.321-0.385) (0.387-0.464) (0.483-0.579) (0.557-0.668) (0.654-0.788) (0.730-0.883) (0.806-0.981) (0.881-1.08) (0.981-1.22) (1.06-1.33) 12-hr 0.206 0.249 0.313 0.364 0.434 0.490 0.548 0.610 0.695 0.764 (0.189-0.226) (0.229-0.274) (0.287-0.343) (0.332-0.399) (0.393-0.474) (0.440-0.534) (0.488-0.597) (0.537-0.663) (0.602-0.755) (0.652-0.830) 24-hr 0.123 0.148 0.186 0.216 0.258 0.292 0.326 0.363 0.413 0.453 (0.113-0.133) (0.137-0.161) (0.172-0.202) (0.199-0.235) (0.236-0.280) (0.266-0.317) (0.297-0.354) (0.329-0.394) (0.372-0.449) (0.406-0.494) 2ilay 0.66-0 078 0.80-0 094 0.100-08117 0.1015 0..1136 0.137-0..1161 0.154-0..1182 0.1071-0 203 0.189-0 226 0.2113-0 257 0.232-0 282 3iiay 0.051 0.061 0.076 0.088 0.104 0.117 0.130 0.144 0.164 0.179 (0.047-0.055) (0.056-0.066) (0.070-0.082) (0.081-0.095) (0.095-0.112) (0.107-0.126) (0.119-0.141) (0.131-0.156) (0.148-0.178) (0.162-0.195) aiiay 0.37--0 043 0.045-0 052 0.055-0 064 0.63-0 074 0.075-0.088 0.84-0.099 0.93 0.110 0.103-0.122 0.1016-0..1138 0.126 0..1152 7iiay 0.026 0.031 0.038 0.044 0.052 0.058 0.064 0.071 0.080 0.087 (0.024-0.028) (0.029-0.034) (0.036-0.041) (0.041-0.047) (0.048-0.055) (0.053-0.062) (0.059-0.069) (0.065-0.076) (0.073-0.086) (0.080-0.094) 10-day 0.021 0.025 0.030 0.034 0.040 0.044 0.049 0.053 0.059 0.065 (0.020-0.022) (0.023-0.027) (0.028-0.032) (0.032-0.037) (0.037-0.043) (0.041-0.047) (0.045-0.052) (0.049-0.057) (0.055-0.064) (0.059-0.069) 20-day 0.014 0.017 0.020 0.022 0.025 0.028 0.031 0.033 0.037 0.040 (0.013-0.015) (0.016-0.018) (0.018-0.021) (0.021-0.023) (0.024-0.027) (0.026-0.030) (0.029-0.033) (0.031-0.035) (0.034-0.039) (0.037-0.042) 30-day 0.011 0.013 0.016 0.017 0.020 0.022 0.023 0.025 0.027 0.029 (0.011-0.012) (0.013-0.014) (0.015-0.017) (0.016-0.018) (0.019-0.021) (0.020-0.023) (0.022-0.025) (0.023-0.027) (0.026-0.029) (0.027-0.031) 45-day 0.009 0.011 0.013 0.014 0.016 0.017 0.018 0.019 0.021 0.022 (0.009-0.010) (0.011-0.012) (0.012-0.013) (0.013-0.015) (0.015-0.017) (0.016-0.018) (0.017-0.019) (0.018-0.021) (0.020-0.022) (0.021-0.024) 60-day 0.008 0.010 0.011 0.012 0.014 0.015 0.016 0.017 0.018 0.019 (0.008-0.009) (0.009-0.010) (0.011-0.012) (0.012-0.013) (0.013-0.014) (0.014-0.015) (0.015-0.016) (0.016-0.017) (0.017-0.019) (0.018-0.020) Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates(for a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds are not checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values. Please refer to NOAAAtlas 14 document for more information. Back to Top PF graphical NOAA Atlas 14,Volume 2,Version 3 Location name: Monroe, North Carolina, USA* � ' Latitude:35.1289*, Longitude: -80.4961° Elevation: 536 ft** 'source:ESRI Maps source.USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M.Bonnin,D.Martin,B.Lin,T.Parzybok,M.Yekta,and D.Riley NOAA,National Weather Service,Silver Spring,Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Average recurrence interval (years) 1 2 5 10 25 50 100 200 500F 1000 5-min 0.415 0.490 0.570 0.627 0.692 0.737 0.777 0.813 0.853 0.881 (0.382-0.452) (0.451-0.534) (0.522-0.620) (0.574-0.681) (0.631-0.750) (0.668-0.798) (0.702-0.842) (0.731-0.882) (0.760-0.927) (0.779-0.959) 10-min 0.663 0.784 0.912 1.00 1.10 1.17 1.24 1.29 1.35 1.39 (0.611-0.721) (0.721-0.855) (0.837-0.993) (0.918-1.09) 1 (1.01-1.20) 11 (1.06-1.27) 11 (1.12-1.34) 1 (1.16-1.40) 11 (1.20-1.47) 1 (1.23-1.51) 15-min 0.829 0.986 1.15 1.27 1.40 1.48 1.56 1.63 1.70 1.74 (0.763-0.901) (0.906-1.07) 1 (1.06-1.26) 11 (1.16-1.38) 1 (1.28-1.52) 11 (1.35-1.61) 11 (1.41-1.69) 1 (1.46-1.76) 11 (1.51-1.84) 1 (1.54-1.90) 30-min 1.14 1.36 1.64 1.84 2.07 2.24 2.39 2.53 2.70 2.82 (1.05-1.24) 11 (1.25-1.48) 1 (1.50-1.78) 11 (1.68-2.00) 1 (1.89-2.24) 11 (2.03-2.42) 11 (2.16-2.59) 1 (2.28-2.74) 11 (2.41-2.94) 1 (2.50-3.07) 60-min 1.42 1.71 2.10 2.39 2.76 3.03 3.29 3.55 3.88 4.12 (1.30-1.54) 11 (1.57-1.86) 1 (1.93-2.29) 11 (2.19-2.60) 1 (2.51-2.99) 11 (2.75-3.29) 11 (2.98-3.57) 1 (3.19-3.85) 11 (3.45-4.21) 1 (3.64-4.48) 2-hr 1.64 1.98 2.46 2.82 3.29 3.64 3.99 4.33 4.78 5.12 (1.50-1.80) (1.82-2.1 7) (2.25-2.69) (2.57-3.08) (2.98-3.58) (3.29-3.96) (3.59-4.35) (3.87-4.72) (4.23-5.22) (4.49-5.60) 3-hr 1.75 2.11 2.63 3.04 3.58 4.00 4.43 4.87 5.46 5.93 (1.60-1.92) (1.93-2.32) (2.40-2.89) (2.76-3.32) (3.24-3.91) (3.60-4.37) (3.96-4.83) (4.32-5.31) (4.79-5.96) (5.14-6.48) 6-hr 2.10 2.53 3.17 3.66 4.33 4.86 5.40 5.96 6.73 7.33 (1.92-2.31) (2.32-2.78) (2.90-3.47) (3.34-4.00) (3.92-4.72) (4.38-5.29) (4.83-5.88) (5.28-6.48) (5.88-7.30) (6.33-7.97) 12-hr 2.49 3.01 3.78 4.39 5.23 5.91 6.61 7.35 8.38 9.21 (2.29-2.73) (2.76-3.31) (3.46-4.14) (4.00-4.81) (4.74-5.71) (5.31-6.44) (5.89-7.19) (6.47-7.99) (7.26-9.10) (7.87-10.0) 24-hr 2.96 3.56 4.48 5.21 6.21 7.01 7.84 8.71 9.92 10.9 (2.73-3.21) (3.30-3.87) (4.13-4.87) (4.79-5.65) (5.69-6.74) (6.40-7.61) (7.14-8.52) (7.90-9.47) 11 (8.94-10.8) 1 (9.77-11.9) 3.47 4.18 5.22 6.04 7.17 8.08 9.02 10.0 11.4 12.4 2tlay (3.21-3.76) (3.87-4.54) (4.82-5.66) (5.57-6.54) (6.59-7.77) (7.40-8.75) (8.23-9.78) (9.08-10.9) 11 (10.3-12.4) 1 (11.2-13.6) 3.68 4.42 5.49 6.34 7.51 8.44 9.41 10.4 11.8 13.0 3tlay (3.41-3.98) 11 (4.10-4.78) 1 (5.08-5.94) 11 (5.85-6.85) 1 (6.90-8.11) 11 (7.74-9.13) 11 (8.60-10.2) 1 (9.49-11.3) 11 (10.7-12.8) 1 (11.7-14.1) 3.89 4.67 5.76 6.63 7.84 8.80 9.80 10.8 12.3 13.5 4tlay (3.61-4.19) 11 (4.33-5.03) 1 (5.34-6.22) 11 (6.13-7.15) 1 (7.22-8.46) 11 (8.09-9.51) 11 (8.98-10.6) 1 (9.89-11.7) (11.2-13.3) (12.2-14.6) 4.48 5.35 6.52 7.46 8.75 9.78 10.8 11.9 13.5 14.8 7tlay (4.19-4.81) (5.01-5.74) (6.10-6.99) (6.96-8.00) (8.13-9.38) (9.07-10.5) (10.0-11.6) 1 (11.0-12.8) (12.4-14.6) (13.5-15.9) 10tlay 5.16 6.14 7.39 8.38 9.71 10.8 11.8 12.9 14.4 15.6 (4.84-5.51) (5.75-6.55) (6.92-7.88) (7.83-8.93) (9.05-10.3) (10.0-11.5) (11.0-12.6) 1 (11.9-13.8) 11 (13.3-15.4) 1 (14.3-16.7) 20tlay 6.93 8.18 9.66 10.8 12.4 13.7 14.9 16.2 17.9 19.3 (6.54-7.35) (7.71-8.67) (9.10-10.2) (10.2-11.5) (11.7-13.2) (12.8-14.5) (13.9-15.9) 1 (15.1-17.2) 11 (16.7-19.1) 1 (17.9-20.6) 30tlay 8.50 9.99 11.6 12.9 14.6 15.9 17.1 18.4 20.1 21.4 (8.03-8.99) (9.46-10.6) (11.0-12.3) (12.2-13.6) (13.7-15.4) (14.9-16.8) (16.1-18.2) (17.2-19.5) (18.8-21.4) (19.9-22.8) 45tlay 10.7 12.6 14.4 15.8 17.6 18.9 20.3 21.6 23.3 24.6 (10.2-11.3) (11.9-13.2) (13.6-15.1) (14.9-16.5) (16.6-18.4) (17.9-19.9) (19.1-21.3) (20.3-22.7) (21.9-24.6) (23.0-26.0) 60tlay 12.8 14.9 16.9 18.4 20.3 21.8 23.2 24.6 26.4 27.7 (12.2-13.4) (14.2-15.6) (16.1-17.6) (17.5-19.2) (19.4-21.3) (20.7-22.8) (22.0-24.4) (23.3-25.8) (24.9-27.8) (26.2-29.2) Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates(for a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds are not checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical PD5-based depth-duration-frequency (DDF) curves Latitude: 35-12991, Longitude- -86-4961" Average recurrence interval 25 tyears) c — t Z- 20 2 a — 5 a -0 15 — 10 a — 25 — 200 a 5 _ — 500 1000 1= E E E 1= fV rt5 4b -Y -0-0 -0 -0 -Q -Q -0-0 i e op 'n N N p 6 6LA 6r•I ,1 rn LO ❑tJfB#IOR .i N rn v to 25 C r 20 Duration C — 5-min — 2-day 15 — 10-min — 3-day a 4.1 15 min — diary 49 — 3d-min — 7-day EL ILO Mmin — 10-day — 24hf — 20 day 5 - — 3-1mr — 30--day 64hu — 45-4ay I2-ftr — 64--day 24-rir 1 2 5 10 25 50 100 2D0 500 3000 Average recurrence interval (yearn) 1+44AA Atlas 14,Volume 2,Version 3 Created(GIYT):Fri Dec 22 15:04:33 2023 Back to Top Maps & aerials Small scale terrain Diversion Swale for Post Construction Channel Calculations-Diversion Swale Project: Grassy Branch WRF Expansion Client: Union County Location: Union County,NC Objective: Design channel to convey flow in a non erosive manner 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 reference. Rational Method will be used to calculate flows. Normal depth will be calculated using Mannings Equation and 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: Post-D�eioped Rational Method: Q=C'I'A Where Q=Flow(cfs) C=Runoff Coefficient I=Rainfall Intensity(in/hr) A=Drainage Area(ac) Find C value in Reference 2 Find Intensity for 10-year event in Reference 2 C= 1= Drainage area(A)(ac)_ Q(cfs)= 27.0 10-year design storm(source:StreamStats) Check channel for adequate depth and for need for armoring Assume 2.5 ft/s as maximum allowable velocity for bare earth and 4.5 ft/s as maximum allowable velocity for grass lined Design channel lining using tractive force procedure Calculations will be done using Manning's Equation to find normal depth and Continuity(Q=V'A)to find velocity. Q(cfs)= 2 7.0 S_(ft/ft)= 0.017 B(ft)= 0 M(ft)= 3 Channel cross section Calculate normal depth and velocity with bare earth as lining From Ref.2, n= 0.02 Flow(cfs)= 27.0 normal depth(ft)= 1.2 velocity(ft/s)= 6.56 Since velocity is greater than the 2.5 ft/s limit for bare earth, M M TEMPORARY OR PERMANENT LINING WILL BE REQUIRED Calculate normal depth and velocity with grass as lining From Ref.2, n= 0.03 Flow(cfs)= 27.0 normal depth(ft)= 1.4 velocity(ft/s)= 4.84 Since velocity is greater than the 4.5 ft/s limit for grass lined, PERMANENT LINING WILL BE REQUIRED Perm-Temp Channel-Grassy Branch Calculate normal depth and velocity for PERMANENT LINING From product manual,n= 0.031 Flow(cfs)= 27.0 normal depth(ft)= 1.4 velocity(ft/s)= 4.72 Calculate shear stress Shear stress(lb/ft2)=(62.4 Ib/ft)'(normal depth)'(slope) shear stress(Ib/ft2 )= 1.46 Use permanent lining with a minimum shear stress shear stress(/b/ft2)= 2.00 Max Permissible Shear Max Velocity Unvegetated Vegetated Unvegetated Vegetated Lining Type Manufaturer and Model n'' Ibs/ft2 Ibs/ft2 ft/s ft/s Straw w/Net-RECM North American Green-S150 0.044 1.75 N/A 6.00 N/A Coconut Fiber-RECM North American Green-C125 0.019 2.25 N/A 10.00 N/A Polypropylene Mat-TRM North American Green-P300 0.029 3.00 8.00 9.00 16.00 Polypropylene Mat-TRM North American Green-P550 0.031 4.00 14.00 12.50 25.00 n value interpolated for normal depth of 1.0 ft Temporary shear stress:1.75-2 Ibs/sf Permanent shear stress:2 Ibs/sf Perm-Temp Channel-Grassy Branch USGS StreamStats Peak Flow Grassy Branch WRF-StrearnStats Report Region ID: NC Workspace ID: NC2O24O1O4175934687OOO Clicked Point(Latitude, Longitude): 35.13067,-80.49433 Time: 2024-01-04 13:00:03-0500 Grassy Branch WRF 1629 Old Fish Rd,Monroe,NC Peak Now O Collapse All Basin Characteristics Parameter Code Parameter Description Value Unit DRNAREA Area that drains to a point on a stream 0.0292 square miles LCO6IMP Percentage of impervious area determined from NLCD 2006 impervious dataset 0.81 percent PCTREG1 Percentage of drainage area located in Region 1 -Piedmont/ Ridge and Valley 100 percent PCTREG2 Percentage of drainage area located in Region 2-Blue Ridge 0 percent PCTREG3 Percentage of drainage area located in Region 3-Sandhills 0 percent PCTREG4 Percentage of drainage area located in Region 4-Coastal Plains 0 percent PCTREG5 Percentage of drainage area located in Region 5-Lower Tifton Uplands 0 percent Peak-Flow Statistics Peak-Flow Statistics Parameters [Region 1 Piedmont rural under 1 sgmi 2014 5030] Parameter Code Parameter Name Value Units Min Limit Max Limit DRNAREA Drainage Area 0.0292 square miles 0.1 1 LCO6IMP Percent Impervious NLCD2OO6 0.81 percent 0 47.9 Peak-Flow Statistics Parameters [Peak Southeast US NC 2023 50061 Parameter Code Parameter Name Value Units Min Limit Max Limit PCTREG1 Percent Area in Region 1 100 percent 0 100 PCTREG2 Percent Area in Region 2 0 percent 0 100 PCTREG3 Percent Area in Region 3 0 percent 0 100 PCTREG5 Percent Area in Region 5 0 percent 0 100 DRNAREA Drainage Area 0.0292 square miles 0.08 8902 PCTREG4 Percent Area in Region 4 0 percent 0 100 Peak-Flow Statistics Disclaimers [Region 1 Piedmont rural under 1 sgmi 2014 50301 One or more of the parameters is outside the suggested range.Estimates were extrapolated with unknown errors. Peak-Flow Statistics Flow Report [Region 1 Piedmont rural under 1 sgmi 2014 5030] Statistic Value Unit 50-percent AEP flood 13.6 ft^3/s 20-percent AEP flood 21.5 ft^3/s 10-percent AEP flood 27 ft^3/s 4-percent AEP flood 33.8 ft^3/s 2-percent AEP flood 39 ft^3/s 1-percent AEP flood 44.2 ft^3/s 0.5-percent AEP flood 49.2 ft^3/s 0.2-percent AEP flood 58.5 ft^3/s Peak-Flow Statistics Disclaimers [Peak Southeast US NC 2023 5006] One or more of the parameters is outside the suggested range.Estimates were extrapolated with unknown errors. Peak-Flow Statistics Flow Report [Peak Southeast US NC 2023 5006] Statistic Value Unit 50-percent AEP flood 15.2 ft^3/s 20-percent AEP flood 28.7 ft^3/s 10-percent AEP flood 40 ft^3/s 4-percent AEP flood 55.9 ft^3/s 2-percent AEP flood 70.3 ft^3/s 1-percent AEP flood 85 ft^3/s 0.5-percent AEP flood 100 ft^3/s 0.2-percent AEP flood 121 ft^3/s Peak-Row Statistics Citations Feaster,T.D.,Gotvald,A.J., and Weaver,J.C.,2014,Methods for estimating the magnitude and frequency of floods for urban and small, rural streams in Georgia, South Carolina, and North Carolina,2011 (ver. 1.1, March 2014): U.S. Geological Survey Scientific Investigations Report 2014-5030, 104 p. (http://pubs.usgs.gov/sir/2014/5030/) Feaster,T.D.,Gotvald,A.J., Musser,J.W.,Weaver,J.C. Kolb, K.R.,Veilleux,A.G., and Wagner, D.M.2023, Magnitude and frequency of floods for rural streams in Georgia, South Carolina,and North Carolina, 2017—Results: U.S. Geological Survey Scientific Investigations Report 2023-5006,75 p. (https://pubs.er.usgs.gov/publication/sir20235006) USGS Data Disclaimer:Unless otherwise stated,all data,metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected.Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S.Geological Survey(USGS),no warranty expressed or implied is made regarding the display or utility of the data for other purposes,nor on all computer systems,nor shall the act of distribution constitute any such warranty. USGS Software Disclaimer:This software has been approved for release bythe U.S.Geological Survey(USGS).Although the software has been subjected to rigorous review,the USGS reserves the right to update the software as needed pursuant to further analysis and review.No warranty,expressed or implied,is made bythe USGS or the U.S.Government as to the functionality ofthe software and related material nor shall the fact of release constitute anysuch warranty.Furthermore,the software is released on condition that neither the USGS northe U.S.Government shall be held liable for any damages resulting from its authorized or unauthorized use. USGS Product Names Disclaimer:Any use oftrade,firm,or product names is for descriptive purposes only and does not imply endorsement by the U.S.Government. Application Version:4.19.2 StrearnStats Services Version:1.2.22 NSS Services Version:2.3.2 Culvert Calculations Culvert Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Wednesday,Jan 31 2024 Circular Culvert Invert Elev Dn (ft) = 513.02 Calculations Pipe Length (ft) = 22.00 Qmin (cfs) = 27.00 Slope (%) = -0.50 Qmax (cfs) = 34.00 Invert Elev Up (ft) = 512.91 Tailwater Elev (ft) = (dc+D)/2 Rise (in) = 30.0 Shape = Circular Highlighted Span (in) = 30.0 Qtotal (cfs) = 27.00 No. Barrels = 1 Qpipe (cfs) = 27.00 n-Value = 0.012 Qovertop (cfs) = 0.00 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 6.05 Culvert Entrance = Square edge w/headwall (C) Veloc Up (ft/s) = 7.27 Coeff. K,M,c,Y,k = 0.0098, 2, 0.0398, 0.67, 0.5 HGL Dn (ft) = 515.16 HGL Up (ft) = 514.68 Embankment Hw Elev (ft) = 515.80 Top Elevation (ft) = 518.70 Hw/D (ft) = 1.16 Top Width (ft) = 11.00 Flow Regime = Inlet Control Crest Width (ft) = 20.00 Elev(ft) CAga Hw Depth(ft) 519.00 6.09 518.00 5.09 517.00 4.09 516.00 3.09 515.00 2.09 514.00 1.09 513.00 0.09 512.00 -0.91 511.00 -1.91 0 5 10 15 20 25 30 35 40 45 GircularGulvert HGL Embank Reach(ft) Riprap Outlet Protection Calculations DESIGN OF RIPRAP OUTLET PROTECTION User Input Data Calculated Value Reference Data Designed By: CAB Date: 1/24/24 Checked By: CJM Date: 1/24/24 Company: Hazen and Sawyer, P.C. Project Name: Grassy Branch WRF Project No.: 30831-070 Site Location (City/Town) Union, NC Temporary and Culvert Id. Permanent Diversion Swales Total Drainage Area (acres) 18.688 Step L Determine the tail-t titer depth from channel clutracteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified nu ti-mum tailwater condition. If it is greater than half the pipe diameter. it is classified maximum condition. Pipes that outlet onto wide flat areas with no defined chatuiel are assumed to have a mm' nium tailwater condition unless reliable flood stage elevations show othemise_ Outlet pipe diameter, Do (in.) 30 Tailwater depth (in.) 25.62 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) 27.0 Velocity (ft./s) 6.05 Step 2. Based on the tailwater conditions determuied in step 1_ enter Figure 8.06a or Figure 8.06b.and determine dsariprap size and ntinimtm apron length (L.). The dr, size is the median stone size in a well-graded riprap apron_ Step ;. Determine apron width at the pipe outlet_ the apron shape. and the apron width at the outlet end from the same figure used in Step ?. Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 0.1 Minimum apron length, La (ft.) 16 12 Apron width at pipe outlet (ft.) 7.5 7.5 Apron shape wedge wedge Apron width at outlet end (ft.) 18.5 7.3 Stela 4. D]-t niiune the maxiniiun stone diaxuetei dt", - 1 .5 x dso Minimum TW Maximum TW Max Stone Diameter, dmax (ft.) 0.75 0.15 Step 5. Deternnine the apron thiclaiess: Apron thickness = 1.5 x dam, Minimum TW Maximum TW Apron Thickness(ft.) 1.125 0.225 Step 6. Fit the nprap apron: to the site by making it le%-el for the nuniminn length. La- from Figure 8.06a or Figure 8.06b. Extend the apron farther don;-ustream and along channel banks until stability is assured_ Keep the apron as straight as possible and align it ssrith the flow of the receiving stream. eke any necessary-abgnxnent bends near the pipe outlet so that the entrance unto the receiving streani is straight. Soule locations mad-regiure luting of the entire channel cross Section to assure stabilirv. It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendix 5.05)_ NX-lere overfalls exist at pipe outlets or flows are excessive. a plunge pool should be considered. see page 8.06.8_ Recommended Riprap Apron Size Apron Length (ft.) 12 Apron Width (ft.) 8 Thickness of Stone (ft.) 1.1 NCDOT Stone Class Class 1 Figure 8.06a: Design of outlet protection from a round pipe flowing full, minimum tailwater condition (Tw<0.5 diameter) 3 0 Outlet W 0o d 90 pipe diameter (Da) La - _ ...h i water - 0.5Qo La,`�til 70 a60 l �u 50 .... ....1................ K I t0% { ..: 4 ...". -'t 4 30 �. { •{ {...: A A .. 2LOL N 77 v v _ 50 4 0 3 5 10 20 51 100 200 500 1000 Discharge 013lsec) Curves may not be extrapolated. Figure 8-06a Design of Outlet protecwn protection from a round pipe flawing full,minimum tailwater condition(7w c 0-5 diamelery Rev.1e*03 8.063 Figure 8.06b: Design of outlet protection from a round pipe flowing full, maximum tailwater condition (Tw>=0.5 diameter) 300 Outlet W = Do + O.4La 120 ----r r pipe j Jr diameter(00)L t.a � 110 11 i _ .500 I00 �y 90 i.- I i " a QQ 70 F- ... � a • 3 30 20 V N �0,• 1� G7 25 0 . - �. ab a 1 ¢ a v- to c ' 1 3 5 10 20 50 100 200 Soo 1000 ❑ischarge(Olsec) Curves may not be extrapolated. Figure S.06b design of outlet pro teclion tram a round pipo flowing full,maximum Iailwater condition(T.?0 5 dame ter) 8.06.4 RPN-.11'93