PERMFILE46840

• Permit No: C1982057A
• IBM Index Class Name: Permit File
• Doc Date: 5/1/2003
• Doc Name: Drainage and Sediment Control Plan
• Section_Exhibit Name: Tab 13 Attachment 13-5B
• Media Type: D
• Archive: Yes

2002 Senera UIY Sonlb F_xpmuion * Drainage and Sediment Contra! Plmi
TABLE 5
SENECA II -W (SOUTH EXPANSION)
SEDIMENTATION POND SUMMARY
POND 15 POND 16 POND 16A POND 17
WATERSHED AREA lacresl:
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 Ift msll 7378.0 7446.0 7505.0 7375.0
Principal Spillway Invert Elevation Ift msll 7390.0 7460.3 7525.0 7391.9
Emergency Spillway Invert Elevation Ift msll 7397.8 7466.5 7527.5 7393.4
Top of Embankment Ift msll 7394.0 7469.4 7530.0 7395.0
Storage Volume Below Principal Spillway lac-ftl 3.62 6.90 16.13 8.12
Storage Volume Below Emergency Spillway lac-ftl 4.71 12.82 20.03 9.74
Principal Spillway Parameters:
Type Drop Inlet Drop Inlet Drop Inlet Drop Inlet
Hole Elevation (if applicable) Ift msl) N/A NIA N/A N/A
Riser Diameter (in) 18 24 48 36
Riser Height Iftl~ 5.0 2.5 3.0 4.9
Barrel Diameter (in) 18 24 48 36
Emergency Spillway Parameters:
Type Trapezoidal Trapezoidal Trapezoidal Trapezoidal
Bottom Width Iftl 10 20 50 20
Length Ift) 60.0 36.0 28,8 24.6
Side Slopes H:1V 2.0/5:0 3.0 3.0 3.0
HYDROLOGIC/HYDRAULIC PARAMETERS:
10-year, 24-hour Storm Event:
Precipitation lint 1.7 1.7 1.7 1.7
Runoff Volume lac-ftl 3.65 18.83 18.59 6.14
Principal Spillway Peak Discharge Icfsl 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 Ift msll 7391.7 7466.2 7527.5 7393.4
25-year, 24-hour Storm Event:
Precipitation lint 2.1 2.1 2.1 2.1
Runoff Volume lac-ftl 5.80 27.01 26.72 9.45
Principal Spillway Peak Discharge (cfs) 0.0 40.3 110.9 48.5
Emergency Spillway Peak Discharge (cfsl 28.4 42.5 80.7 6.7
Peak Surface Water Stage Elevation Ift msll 7392.9 7467.5 7528.3 7393.9
Pond Freeboard Iftl 1.05 1.9 1.6 1.1
SEDIMENT LOADING PARAMETERS: See Note 1
Storm Predicted Peak Settleable Concentration
(ml/II 0.00 0.00 4.67 0.00
Predicted Annual Sediment Loading lac-ftl 1.21 3.11 12.37 2.56
Available Sediment Storage Volume lac-ftl 3.62 6.12 12.37 8.12
Maximum Sediment Storage Elevation Ift 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 being the lower ond.
MWH * 765 S. Unron Boulevard, Suite 470 * Lnkemaad, Colorado 80228 * (970J 763-5140
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