2013-10-07_PERMIT FILE - C1981025A ‎(6)‎

• Permit No: C1981025A
• IBM Index Class Name: Permit File
• Doc Date: 10/7/2013
• Doc Name: Final Engineering Calculations
• Section_Exhibit Name: 4.0 Appendix 4-B
• Media Type: D
• Archive: Yes

• DIVERSION DITCH ABOVE TREATMENT PONDS T-1 AND T-2 4/6
PEAK FLOW CALCULATIONS
T-1 & T-2 T-1 & T-2
DIVERSION DIVERSION
SITE ACCESS ROAD
DRAINAGE AREA (ACRES) 2.79 0.24
CURVE N0. 70 82
STORM EVENT YR., 24 HR. 25 25
STORM EVENT in. 2.2 2.2
RUNOFF in. 0.320 0.784
WATERSHED RELIEF ft. 58
Lc 25 ft. 450
Lc 50 ft. 360
Lc 75 ft. 225
WATERSHED SLOPE 12.3 12.3
SLOPE ADJUSTMENT FACTOR 0.97 0.97
LENGHT OF WATERSHED 380 380
EQUIVALENT DRAINAGE AREA 2.71 2.71
PEAK FLOW cfs/in Fig D-2 4.2 0.29
ADJUSTED PEAK FLOW 1.34 CFS 0.02 CFS
TOTAL DESIGN FLOW 1 .36 CFS
• DIVERSION DITCH ABOVE T-1 AND T-2 PONDS
FLOW IN A TRIANGULAR CHANNEL
DEPTH D 0.700 FEET
SLOPE S 0.010 EXPRESS AS DECIMAL
MANNINGS "N" N 0.030 EXPRESS AS DECIMAL
SIDE SLOPE X 1.500 SLOPE = X:1
AREA=(W*D)+(X*D^2)= 0.74 FEET^2
WETTED PERIMETER=(W)+2((XD^2+ D^2))^.5 2.52 FEET
R=AREA/WETTED PERMITER 0.29
V=(1.49/N)*(R^.667)*(S^.5)= 2.18 FEET/SEC
Q = A X V = 1.60 CFS
Q REQUIRED 1.36
The diversion ditch will be a triangular cha nnel 0.7
feet deep with 1.5h: 1v side slopes. With a freeboard of 0.3'
the total depth of t he upper diversion ditch is 1.0 foot.
The flow velocity is slow en ough that erosio n will not be a
problem.
•
P-9-8
08-14-95