2008-03-03_PERMIT FILE - C2006085A ‎(4)‎

• Permit No: C2006085A
• IBM Index Class Name: Permit File
• Doc Date: 3/3/2008
• Doc Name: Drainage and Sediment Control Plan
• Section_Exhibit Name: Exhibit V
• Media Type: D
• Archive: Yes

TABLE 3
Northfield Pro'ect Sediment Pond Summar
WATERSHED AREA acres
Disturbed 14.6
Undisturbed 0.0
Total Area 14.6
OND PARAMETERS:
Bottom Elevation 5391.5
Princi al S illwa Invert Elevation 5392.0
Emer enc S illwa Invert Elevation 5394.0
To of Embankment 5396.0
Stora a Volume Below Emer enc S illwa ac-ft 1.74
Stora a Volume Below Princi al S illwa ac-ft 0.32
Princi al S illwa Parameters:
T e Perforated Riser
Riser Diameter in 24
Riser Hei t 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
Emer enc S illwa Parameters:
T e Tra ezoidal
Bottom Width (ft 28
Crest Len h ft 10
Side Slo es 3H:1V
YDROLOGIC/HYDRAULIC PARAMETERS:
Mine Dewaterin Flow ( m) 30
10-Year, 24-Hour Storm Event:
Preci itation in 2.5
Run-off Volume ac-ft) 1.43
Princi al S illwa Peak Dischar a cfs 0.45
Emer enc S illwa Peak Dischar a cfs 0.0
Peak Surface Water Sta a Elevation ft 5,393.49
25-Year, 24-Hour Storm Event:
Preci itation in 2.9
Run-off Volume ac-ft 1.83
Princi al S illwa Peak Dischar e cfs N/A
Emer enc S illwa Peak Dischar a cfs 15.8
Peak Surface Water Sta a Elevation cfs 1 5,394.8
Pond Freeboard ft 1.2
SEDIMENT LOADING PARAMETERS
10-Year, 24-Hour Storm Event:
Predicted Peak Settleable Concentration In mUl 114.73
Predicted Peak Settleable Concentration Out mUl 0.00
Predicted Annual Sediment Loadin ac-ft 0.10
Available Sediment Stora a Volume ac-ft 0.32
Maximum Sediment Stora a Elevation ft 5,392.0
Predicted Number of Stora a Years 3.0
For preliminary conceptual design of the creek crossing, a detailed hydrologic study of the Chandler
Creek basin was not performed. As a guide to the crossing design, the Fremont County Road 11A
bridge crossing downstream of the site was used. According to discussions with Fremont County
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