_PERMIT FILE - C1981008A ‎(13)‎

• Permit No: C1981008A
• IBM Index Class Name: PERMIT FILE
• Doc Name: Sedimentation Pond 004
• Section_Exhibit Name: Tab 13 Attachment D
• Media Type: D
• Archive: Yes

Pond No. 004 - East Ditch
In order to contain runoff from the existing reclaimed, a contour ditch
is required along the reclaimed area east of Pond No. 004, flowing into
Pond No. 004 (see Exhibit 13-4) .
For the design of the contour ditch, the SEDIMOT II model was used to
predict the runoff from the watershed (see Addendum D for the batch
input and output, respectively) . The 10-year, 24-hour precipitation
event was used in the design, which is a conservative approach to a
temporary ditch.
Following is a list of the main input factors which were derived in the
same manner to the factors of Pond No. 004:
Input East Ditch
Precipitation 1.60"
Drainage Area 6.3 ac
CN 81
L 0.186 miles
H 95 ft.
tc 0.064
Output
Q (cfs) 2.6 cfs
Based on these discharges, the Dodson and Associates, Inc. 's computer
software was used to design the ditches based on Manning's equation
calculations.
Two ditch designs are proposed for the east ditches. Based on the
critical slope calculations for the ditch, a ditch section will be
constructed with riprap or without riprap, depending on whether the
ditch' s slope is steeper or flatter than critical slope. Each ditch
will have a minimum of one foot of freeboard included in the total
depth. This will allow the ditch to be field-located as close as
practical to the reclamation area, but still control all runoff and
direct the flow to Pond 004 (See Exhibit 13-4) .
Following is a summary of "Alternative A" and "Alternative B" ditch
design to be used for East Ditch.
11