PERMFILE121541

• Permit No: C1981018A
• IBM Index Class Name: Permit File
• Doc Date: 5/13/2002
• Doc Name: Sediment Control Design Calculations, old NPDES permit
• Section_Exhibit Name: Illustration 07 through 13
• Media Type: D
• Archive: Yes

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NORTH TOPSOIL STOCKPILE DITCH
(ADD TO ILLUSTRATION 7)
Contributing Drainage Aree = 0.90 acres
To determine Q actual, compare to runoff from other sections of the same topsoil
stockpile.
West Topsoil Ditch: Q = 5.7 ft~/sec, Area = 2.43 acres Q/A = 2.35 ftJ/sec/acre
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East Topsoil Ditch: Q = 3.6 fts/sec, Area = 1.45 acres Q/A = 2.48 ft~/sec/acre
Use Average Q/A for North Topsoil Ditch:
Q/A = 2.42 ft3/sec/acre
A =Contributing Drainage Area = 0.90 acres
Q required =(2.42)(0.90) = 2.18 ft~/sec
Lining Material = Riprap
therefore, n = 0.04
therefore, Max V = 12
For D = 0.6
2.18
A=2D==0.72
Wp=2 5D==2.68
R=A/Wp=0.268
5 = 0.06
V = ].49 ARp/s gi/a
n
_ (37.25)(0.72)(0.42)(.245)
= 2.76
Q = VA =(2.76)(0.72) = 1.98 NO
Therefore, total Ditch depth = 0.7 + 0.3 = 1.0'
For D = 0.7
Q = 2.18
A=2D==0.98
Wp = 2~5D~ = 3.13
R=A/Wp = 0.31
S = 0.06
V = 1.49 (0.98)(0.46)(0.245)
n
= 1.49 (0.98)(0.46)(0.295)
n
= 4.11
Q = VA =(4.11)(.98) = 4.03 OH