PERMFILE114555

• Permit No: C1982057A
• IBM Index Class Name: Permit File
• Doc Date: 7/15/2005
• Doc Name: Drainage and Sediment Control Plan II-W South Extension
• Section_Exhibit Name: Tab 13 Attachment 13-5B
• Media Type: D
• Archive: Yes

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January 2002 Srnera IPf~Soutb E.xpan.nan * Drainage and Sediment Contra/Pkn * Page 7
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TABLE 5
SENECA ll-W (SOUTH EXPANSION)
SEDIMENTATION POND SUMMARY
POND 15 POND 016 POND 016A POND 017
WATERSHED AREA (acres):
Disturbed 39.3 2733 273.3 80.3
Undisturbed 367.4 106.4 48.2 878.3
Total Area 406.7 379.7 321.5 958.6
POND PARAMETERS:
Bottom Elevation (ft msl) 7378.0 7446.0 7505.0 7375.0
Principal Spillway Invert Elevation 7390.0 7462.0 7525.5 7391.9
Emergency Spillway Invert Elevation 7391.8 74653 7527.9 7393.4
Top of Embankment 7394.0 7468$ 7530.0 7395.0
Storage Volume below Principal Spillway (ac-ft) 3.62 7.6 11.2 8.12
Storage Volume below Emergency Spillway 4.71 10.7 15.7 9.74
Principal Spillway Parameters:
Type Drop Inlet Drop Inlet Drop Inlet Drop Inlet
Hole Elevation (if applicable) N/A N/A N/A N/A
Riser Diameter (in) 1 B 24 48 36
Riser Height (ft) 5.0 5.0 4.1 4.9
Barrel Diameter (in) 1 B 24 48 36
Emergency Spillway Parameters:
Type Trapezoidal Trapezoidal Trapezoidal Trapezoidal
Bottom Width (ft) I O 20 48 20
Length (ft) 60.0 31,6 27.0 24.6
Side Slopes_HaV 2.015.0 3.0 3.0 3.0
HYDROLOGIC/HYDRAULIC PARAMETERS:
10-yeaz/24 hour Storm Event:
Precipitation (in) 1.7 1.7 1.7 1.7
Runoff Volume (ac-ft) 3.65 0.26 12.82 6.14
Principal Spillway Peak Discharge (cfs) I1.1 27.1 71.6 41.4
Emergency Spillway Peak Discharge (cfs) 0.0 0.0 0.0 0.0
Peak Surface Water Stage Elevation (fl msl) 7391.7 74653 75265 7393.4
25-yeaz/24-hour Stonn Event:
Precipitation (in) 2.1 2.1 2.1 2.1
Runoff Volume (ac-ft) 5.80 03 19.0 9.45
Principal Spillway Peak Discharge (cfs) 0.0 0.0 91.7 48.5
Emergency Spillway Peak Discharge (cfs) 26.4 66.8 0.0 6.7
Peak Surface Water Stage Elevation (fl msl) 7392.9 7466.2 7527.8 7393.9
Pond Freeboard (ft) 1.1 2.6 2.7 1.1
SEDIMENT LOADING PARAMETERS:
Storm Predicted Peak Settleable Concentration
(mUl) 0.00 0.2 4.67 0.00
Predicted Annual Sediment Loading (ac-fl) 1.21 0.75 6.7 2.56
Available Sediment Storage Volume (ac-ft) 3.62 0.75 6.7 8.12
Maximum Sediment Storage Elevation (ft msl) 7390.0 7448.9 7516.9 7391.9
Predicted Number of Storage Years 3.0 1.0 1.0 3.2
Notes:
1. Pond 016A and Pond 016 are in series, with Pond 0 ] 6A being the upper pond in sequence and Pond 016 being the
lower pond.
2. Pond 016A designed and constructed for maximum disturbance. Pond 016 designed and construMed for
actual tits-of-mine conditions (reduced disturbance .
TR-53
Revised 6/05