SW3210702_Design Calculations_20211103

STORMWATER
CALCULATIONS
FOR
PROVISION CHURCH
UNION COUNTY, NORTH CAROLINA
REV.
NOVEMBER 1, 2021
w
�SEAL`�
19311
NEAL SMITH ENGINEERING, INC. Project No. 2101403 1118001"lit"t,,,,
Neal S pn ith T'nlivi eerinj,
139 Pinehurst Ave, — Suite C
Southern Pines, NC 28387
Phone: [phone]
Fax: [phone]
www nsengineerin2.ram
License No. C-1425

STORMWATER CONVEYANCE CALCULATIONS
CHANNEL #1
STORMWATER FLOW
Q=CiA
C=
0.68
i=
7.66 (10 YR)
A=
0.69 ACRES
Q=
3.59 CFS
Q Pond=
0 cfs
otal=
3.59 CFS
Bottom Width
"b" = 2.00 feet
Depth of Water
"y" = 0.75 feet
Left Side Slope
"z" = 3 to 1
Right Side Slope
"z" = 3 to 1
Diameter
"d" = feet
Slope
"s" = 0.0500 feet per foot
Mannin 's
"n" = 0.030 earth channel/grassed
4.75
10 Yr. Actual
Section
Area
s . ft.
Wetted
Perimeter
feet
Hydraulic
Radius
feet
Channel
Conveyance
cfs
Velocity
ft/sec
Trapezoid,
3.19
6.7434
0.4727
21.42
5.00

STORMWATER CONVEYANCE CALCULATIONS
CHANNEL #2
STORMWATER FLOW
Q=CiA
C= 0.88
i= 7.66 (10 YR)
A= 0.375 ACRES
Q= 2.53 CFS
Q Pond= 0 cfs
Tota = 2.53 CFS
Bottom Width
"b" =
2.00
feet
Depth of Water
"y" =
0.50
feet
Left Side Slope
"z" =
3
to 1
Right Side Slope
"z" =
3
to 1
Diameter
"d" =
feet
Slope
"s" =
0.0500
feet per foot
Manning's
"n" =
0.030
earth channel/grassed
Section
Area
(sq. ft.
Wetted
Perimeter
feet
Hydraulic
Radius
feet
Channel
Conveyance
cfs
Velocity
ft/sec
Trapezoid,
1.75
5.1623
0.3390
9.42
5.00
4.50
Allowable
10 Yr. Actual

STORMWATER CONVEYANCE CALCULATIONS
CHANNEL #3
STORMWATER FLOW
Q=CiA
C=
0.89
i=
7.66 (10 YR)
A=
0.106 ACRES
Q=
0.72 CFS
Q Pond=
0 cfs
otal=
0.72 US
Bottom Width
"b" = 2.00 feet
Depth of Water
"y" = 0.50 feet
Left Side Slope
"z" = 3 to 1
Right Side Slope
"z" = 3 to 1
Diameter
"d" = feet
Slope
"s" = 0.0500 feet per foot
Mannin 's
"n" = 0.030 earth channel/grassed
3.63 10 Yr. Actual
Section
Area
s . ft.
Wetted
Perimeter
feet
Hydraulic
Radius
feet
Channel
Conveyance
cfs
Velocity
ft/sec
Trapezoid
1.75
5.1623
0.3390
5.00

STORMWATER CONVEYANCE CALCULATIONS
CHANNEL #4
STORMWATER FLOW
Q=CiA
C=
0.69
i=
7.66 (10 YR)
A=
0.909 ACRES
Q=
4.80 CFS
Q Pond=
0 cfs
otal=
4.80 CFS
Bottom Width
"b" = 2.00 feet
Depth of Water
"y" = 0.75 feet
Left Side Slope
"z" = 3 to 1
Right Side Slope
"z" = 3 to 1
Diameter
"d" = feet
Slope
"s" = 0.0500 feet per foot
Mannin 's
"n" = 0.030 earth channel/grassed
4.96 10 Yr. Actual
Section
Area
s . ft.
Wetted
Perimeter
feet
Hydraulic
Radius
feet
Channel
Conveyance
cfs
Velocity
ft/sec
Trapezoid
3.19
6.7434
0.4727
21.42
5.00

NOAA Atlas 14, Volume 2, Version 3
Location name: Monroe, North Carolina, USA*�
NALatitude: 35.0614°, Longitude:-80.4521'
Elevation: 542.3 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/
Average recurrence interval (years)
Duration O�OOOO�OOr
1 2 5 10 25 50 100 200 500 L
5.08 5.99 6.95 7.66 8.45 8.99 9.49 9.94 10.4 r
5-min
(4.67-5.51) (5.50-6.53) (6.37-7.57) (7.00-8.30) (7.70-9.16) (8.16-9.74) (8.57-10.3) (8.93-10.8) 11 (9.30-11.4) L
4.05 4.79 5.57 6.12 6.73 7.16 7.54 7.87 8.26 r
10-min
(3.73-4.40) (4.40-5.22) (5.11-6.06) (5.60-6.64) (6.13-7.30) (6.50-7.76) (6.81-8.17) (7.07-8.54)1 (7.35-8.98) L
3.38 4.01 4.70 5.16 5.69 6.04 6.35 6.627 6.92 r
15-min
(3.10-3.67) (3.68-4.38) (4.30-5.11) 1 (5.48-6.55) (5.74-6.89) (5.95-7.19) (6.17-7.53) L
2.31 2.77 3.34 3.74 4.21 4.55 4.87 5.15 5.51 r
30-min
(2.13-2.51) (2.55-3.02) (3.06-3.63) 1 (4.13-4.93)
1.44 1.74 2.14 2.43 2.80 3.08 3.35 3.62 3.95 r
60-min
(1.33-1.57) (1.60-1.90) (1.96-2.33) (2.23-2.64) (2.56-3.04)1 (2.80-3.34) 1 (3.52-4.30) L
0.834 1.01 1.25 1.44 1.67 1.85 2.03 2.21 2.44 r
2-hr
(0.764-0.912)1 1 (1.67-2.02) 1 (2.15-2.66) L
0.590 0.713 0.890 1.03 1.21 1.36 1.50 1.65 1.86 7r
3-hr
(0.540-0.649) (0.652-0.785) (0.813-0.979) 1 (1.22-1.48) 1 (1.62-2.03) L
0.356 0.429 0.536 0.620 F 0.733 0.824 0.916 1.01 1.14 r
6-hr
(0.325-0.391) (0.393-0.471) (0.490-0.588) (0.565-0.679) (0.664-0.800) (0.740-0.897) (0.818-0.997) (0.894-1.10) (0.997-1.24) L
0.209 0.253 0.317 0.369 0.439 0.497 0.556 0.618 0.706 r
12-hr
(0.192-0.230) (0.232-0.278) (0.290-0.348) (0.336-0.404) (0.398-0.480) (0.446-0.542) (0.495-0.606) (0.544-0.673) (0.611-0.767)
0.125 0.150 0.189 0.220 0.262 0.296 0.332 0.369 0.421 r
24-hr
(0.115-0.135) (0.139-0.163) (0.174-0.205) (0.202-0.238) (0.240-0.284) (0.270-0.321) (0.301-0.360) (0.334-0.401) (0.378-0.457)
0.073 0.088 0.110 0.128 0.152 0.171 0.191 0.212 0.241 r
2-day
(0.068-0.079) (0.082-0.096) (0.102-0.119) (0.117-0.138) (0.139-0.164) (0.156-0.185) (0.174-0.207) (0.192-0.230) (0.217-0.263)
0.052 0.062 0.077 0.089 0.106 0.119 0.133 0.147 0.167 r
3-day
(0.048-0.056) (0.058-0.067) (0.071-0.084) (0.082-0.096) (0.097-0.114) (0.109-0.129) (0.121-0.144) (0.134-0.159) (0.151-0.182)
0.041 0.049 0.061 0.070 0.083 0.093 0.104 0.115 0.130 r
4-day
(0.038-0.044) (0.046-0.053) (0.056-0.066) (0.065-0.076) (0.076-0.089) (0.085-0.100) (0.095-0.112) (0.105-0.124) (0.118-0.141)
0.027 0.032 0.039 0.045 0.053 0.059 0.065 0.072 0.082 r
7-day
(0.025-0.029) (0.030-0.035) (0.037-0.042) (0.042-0.048) (0.049-0.057) (0.055-0.063) (0.060-0.070) (0.066-0.078) (0.075-0.088)
0.022 0.026 0.031 0.035 0.041 0.045 0.050 0.055 0.061 r
10-day
(0.020-0.023) (0.024-0.028) (0.029-0.033) (0.033-0.038) (0.038-0.044) (0.042-0.048) (0.046-0.053) (0.051-0.058) (0.056-0.065)
0.015 0.017 0.020 0.023 0.026 0.029 0.032 0.034 0.038 r
20-day
(0.014-0.016) (0.016-0.018) (0.019-0.022) (0.022-0.024) (0.025-0.028) (0.027-0.031) (0.029-0.034) (0.032-0.036) (0.035-0.040)
0.012 0.014 0.016 0.018 0.021 0.022 0.024 0.026 0.028 r
30-day
(0.011-0.013) (0.013-0.015) (0.015-0.017) (0.017-0.019) (0.019-0.022) (0.021-0.024) (0.023-0.026) (0.024-0.027) (0.026-0.030)
0.010 7 F 0.012 7 F 0.013 7 F 0.015 7 F 0.017 7 F 0.018 7 F 0.019 7 F 0.020 7 F 0.022 7 r
45-day
(0.010-0.011) 11 (0.011-0.012) (0.013-0.014) (0.014-0.016) (0.016-0.017) (0.017-0.019) (0.018-0.020) (0.019-0.021) (0.021-0.023)
0.009 7 F 0.011 7 F 0.012 7 F 0.013 7 F 0.014 7 F 0.015 7 F 0.016 7 F 0.017 7 F 0.019 7 r
60-day
(0.009-0.009) (0.010-0.011) (0.011-0.012) (0.012-0.014) (0.014-0.015) (0.015-0.016) (0.016-0.017) (0.016-0.018) (0.018-0.020)
frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Fciptation
bersparenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estii
duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bound