PERMFILE109990

• Permit No: C1982057A
• IBM Index Class Name: Permit File
• Doc Date: 6/16/2006
• Doc Name: Drainge and Sediment Control Plan II-W South Extension
• Section_Exhibit Name: Tab 13 Attachment 13-5B
• Media Type: D
• Archive: Yes

January 2002 Seneca IPY~Soutb Expansion * Drainage and Sediment Cantm! Alan 1 Page 7
i

TABLE 5
SENECA II -W {SOUTH EXPANSION)
SEDIMENTATION POND SUMMARY
POND 15 POND 16 POND 16A POND 17
WATERSHED AREA (acres):
Disturbed 39.3 315.7 314.0 80.3
Undisturbed 367.4 69.1 64.0 878.3
Total Area 406.7 384.8 378.0 958.6
POND PARAMETERS:
Bottom Elevation (ft msl) 7378.0 7446.0 7505.0 7375.0
Principal Spillway InveR Elevation (ft msI) 7390.0 7460.3 7525.0 7391.9
Emergency Spillway Invert Elevation (ft msl) 7391.8 7466.5 7527.5 7393.4
Top of Embankment (ft msl) 7394.0 7469.4 7530.0 7395.0
Storage Volume Below Principal Spillway (ac-ft) 3.62 6.90 16.13 8.12
Storage Volume Below Emergency Spillway (ac-ft) 4.71 12.82 20.03 9.74
Principal Spillway Parameters:
Type Drop Inlet
Hole Elevation (if applicable) (ft msl) N/A Drop Inlet Drop Inlet Drop Inlet
Riser Diameter (in) 18 N/A NIA NIA
Riser Height (ft) 5.0 24 48 36
Barre! Diameter (in) 18 2.5 3.0 4.9
24 48 36
Emergency Spillway Parameters:
Type Trapezoidal
Bottom Width (ft) 10 Trapezoida Trapezoidal Trapezoida
Length (ft) 60.0 I 50 I
Side Slopes H:1V 2.0/5.0 20 28.8 20
36.0 3.0 24.6
3.0 3.0
HYDROLOGIC/HYDRAULIC PARAMETERS:
10-year, 24-hour Storm Event:
Precipitation (in) 1.7 1.7 1.7 1.7
Runoff Volume (ac-ft) 3.65 18.83 18.59 6.14
Principal Spillway Peak Discharge (cfs) 11.1 36.6 94.9 41.4
Emergency Spillway Peak Discharge (cfs} 0.0 0.0 0.0 0.0
Peak Surface Water Stage Elevation (ft msl) 7391.7 7466.2 7527.5 7393.4
25-year, 24-hour Storm Event:
Precipitation (in) 2.1
2
1
2.1
2.1
Runoff Volume (ac-ft) 5.80 .
Principal Spillway Peak Discharge (cfs) 0.0 27.01 26.72 9.45
Emergency Spillway Peak Discharge (cfs) 2g,4 40.3 110.9 48.5
Peak Surface Water Stage Elevation (ft msl) 7392.9 42.5 80.7 6.7
Pond Freeboard (ft) 1.05 7467.5 7528.3 7393.9
1.9 1.6 1.1
SEDIMENT LOADING PARAMETERS: See Note 1
Storm Predictetl Peak Settleable Concentration
(ml/I) 0.00 0.00 4.67 0.00
Predicted Annual Sediment Loading (ac-ft) 1.21 3.11 12.37 2.56
Available Sediment Storage Volume (ac-ft) 3.62 6.12 12.37 8.12
Maximum Sediment Storage Elevation (ft msl) 7390.0 7459.3 7522.2 7391,9
Predicted Number of Storage Years 3.0 2.0 1.0 3.2
Notes: 1. Pond 16A and Pond 16 are in series, with Pond 16A being the upper pond in sequence and Pond 16
bein the lower and.
MlY/H * 765 S. Uman Boulevard, Suite 4 r0 * Lakewood, Colorado 80228 * (970J 763-5740
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