Outlet_Analysis_1306_combined.pdf

U-5870 Pitt County, NC
Portertown Road
PRE -CONSTRUCTION Al- 132+80 RT I POST -CONSTRUCTION
TC =
Cw =
60.00
0.40
min.
69.26
3.42
0.00
14.15
51.69
0.00
0.00
0.90
0.35
0.30
0.40
0.70
0.20
n/a
n/a
1.0
1.0
1.0
1.0
1.0
1.0
Total Drainage Area (acres)
69.26
7.97
0.00
14.15
47.14
0.00
0.00
0.90
0.35
0.30
0.40
0.70
0.20
n/a
n/a
1.0
1.0
1.0
1.0
1.0
1.0
TC = 60.00 min.
Cw = 0.44
Paved DA (acres)
Grassed DA (acres)
Park DA (acres)
Residential DA (acres)
Commercial DA (acres)
Agricultural DA (acres)
Runoff Coefficient
12 = 1.80 in/hr
15 = 2.18 in/hr
110 = 2.58 in/hr
125 = 2.98 in/hr
150 = 3.36 in/hr
1100 = 3.75 in/hr
12 = 1.80
15 = 2.18
110 = 2.58
125 = 2.98
150 = 3.36
1100 = 3.75
in/hr
in/hr
in/hr
in/hr
in/hr
in/hr
02 = 50 cfs
05 = 61 cfs
010 = 72 cfs
025 = 83 cfs
050 = 94 cfs
0100 = 105 cfs
02 = 54 cfs
05 = 66 cfs
010 = 78 cfs
025 = 90 cfs
050 = 102 cfs
0100 = 114 cfs
Outlet Condition
Paved Area
Grassed Area
Park Area
Residential Area
Commercial Area
Outlet Condition
Agricultural Area
Other Watershed Info
Length of Travel (feet)
Elevation Difference (feet)
Cf 2-year
D2 = 2.05 feet
V2 = 2.78 fps
D2 = 2.11 feet
V2 = 2.83 fps
D5 = 2.26 feet
V5 = 2.93 fps
Ds = 2.33 feet
Vs = 2.98 fps
D10 = 2.45 feet
V10 = 3.06 fps
D10 = 2.53 feet
V10 = 3.11 fps
Des = 2.63 feet
V25 = 3.18 fps
D25 = 2.71 feet
V25 = 3.23 fps
Cf 5-year
D50 = 2.79 feet
V50 = 3.28 fps
Cf 10-year
D50 = 2.88 feet
V50 = 3.34 fps
Cf 25-year
D100 = 2.94 feet
V100 = 3.38 fps
Cf 50-year
D100 = 3.03
V100 = 3.43
feet
fps
Cf 100-year
Rational Method Weighted C Value = Cv,,
Q = C*1*A*Cf I Cw =E (DAL-d use*CL-d use) / E DA
Notes: Rational Method used for outlet analysis comparison purposes only.
DA is just downstream of outlet pipe @ STA 1 32+80 -L1- RT
Pinewood Cemetery is considered Park Area for this analysis.
Additional Information:
1) Downstream Hardee Creek recieves run-off (Stream Index No. - 28-97; Classification - C;NSW).
2) Downstream properties will see an increase in discharges and velocities.
3) Percent increase in discharge at ROW: 10 yr=8.3%, 25 yr=8.4%, 50 yr=8.5%, 100 yr=8.6%
Percent increase in depth at ROW: 10 yr=3.3%, 25 yr=3.0%, 50 yr=3.2%, 100 yr=3.1 %
Percent increase in velocity at ROW: 10 yr=1.6%, 25 yr=1.6%, 50 yr=1.8%, 100 yr=1.5%
Outlet Channel Dimensions
Base: 4.0'-5.0', Depth: 3.0', Sideslopes: 1.5:1, n-Val: 0.045
No scour in channel, some vegetation along channel.
3/13/2019
4:56 PM X:\2016\WR16.001.00 U-5870 Pitt County\Hydraulics\CALCULATIONS\Outfalls\Outfall_Analysis_1306_combined.xls