2010-05-07_PERMIT FILE - C2006085 ‎(7)‎

• Permit No: C2006085
• IBM Index Class Name: Permit File
• Doc Date: 5/7/2010
• Doc Name: Drainage and Sediment Control Plan
• Section_Exhibit Name: Exhibit V
• Media Type: D
• Archive: No

C.
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C TABLE 3
Northfield Project Sediment Pond Summar
WATERSHED AREA (acres):
Disturbed
15.44
Undisturbed
0.0
Total Area
15.44
POND PARAMETERS:
Bottom Elevation
5391.5
Principal Spillway Invert Elevation
5392.0
Emergency Spillway Invert Elevation
5394.0
Top of Embankment
5396.0
Storage Volume Below Emergency Spillway ac -ft
1.74
Storage Volume Below Principal Spillway ac -ft
0.32
Principal Spillway Parameters:
Type
Perforated Riser
Riser Diameter in
24
Riser Height ft
3
Barrel Diameter in
24
Number of Holes in Riser
8
Size of Holes in
1.5
Elev. of Holes
(5,392.0), 5,393.0
Emergency Spillway Parameters:
Type
Trapezoidal
Bottom Width ft
28
Crest Length ft
10
Side Slopes
3H:1 V
HYDROLOGIC /HYDRAULIC PARAMETERS:
Mine Dewaterin Flow m
50
10 -Year, 24 -Hour Storm Event:
Precipitation in
2.5
Run -off Volume ac -ft
1.51
Principal Spillway Peak Discharge cfs
0.47
Emergency Spillway Peak Discharge cfs
0.0
Peak Surface Water Stage Elevation ft
5,393.57
25 -Year, 24 -Hour Storm Event:
Precipitation in
2.9
Run -off Volume ac -ft
1.93
Principal Spillway Peak Discharge cfs
N/A
Emergency Spillway Peak Discharge cfs
17.08
Peak Surface Water Stage Elevation cfs 1
5,394.85
Pond Freeboard ft
1.15
SEDIMENT LOADING PARAMETERS
10 -Year, 24 -Hour Storm Event:
Predicted Peak Settleable Concentration In ml /1
115.25
Predicted Peak Settleable Concentration Out ml /1
0.00
Predicted Annual Sediment Loading ac -ft
0.11
Available Sediment Storage Volume ac -ft
0.32
Maximum Sediment Storage Elevation (ft)
5,392.0
Predicted Number of Storage Years
3.0