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0 <br />E <br />COLOWYO COAL COMPANY <br />0011A - STREETER <br />SEDIMENTATION POND SUMMARY <br />Exh. 7 -SP -20 Revision Date: 2/1/06 <br />Revision No.: TR -63 <br />ORIGINAL <br />1996 <br />1998 <br />2006 <br />DIFFERENCE <br />CONFIGURATION <br />STUDY <br />STUDY <br />DIFFERENCE <br />STUDY <br />1998 TO 2006 <br />WATERSHED AREA (acres): <br />Disturbed <br />0.0 <br />0.0 <br />0.0 <br />0.0 <br />Postmining Topsolfedl and Seeded <br />50.6 <br />231,3 <br />180.7 <br />471,5 <br />240.2 <br />Postmining Undisturbed <br />207.0 <br />53,8 <br />-153.2 <br />148.1 <br />94.3 <br />1 -2 Year Reclamation <br />23.0 <br />79.4 <br />56.4 <br />68.5 <br />-10.9 <br />3+ Year Reclamation <br />845.5 <br />843.3 <br />-2.2 <br />620.4 <br />-222.9 <br />Total Area <br />1126.1 <br />1207.8 <br />81.7 1 <br />11308.5 1 <br />100.7 <br />OND PARAMETERS: <br />I <br />Bottom Elevation <br />6576.7 <br />6576.7 <br />6579,0 <br />2.3 <br />6578.0 <br />-1.0 <br />Principal Spillway invert Elevation <br />6586.9 <br />6586.7 <br />6585.0 <br />-1.7 <br />6585.0 <br />0.0 <br />Emergency Spillway Invert Elevation <br />6588.0 <br />6588.0 <br />6588.0 <br />0.0 <br />6588.0 <br />0.0 <br />Top of Embankment <br />6590.0 <br />6590.0 <br />6591.0 <br />1.0 <br />6591.0 <br />0.0 <br />Storage Volume Below Emergency Spillway (ac -ft) <br />111,08 <br />11.08 <br />11.17 <br />0.09 <br />11.2 <br />0.0 <br />Storage Volume Below Principal Spillway (ac -ft) <br />6.12 <br />8.39 <br />521 <br />-3.18 <br />5.2 <br />010 <br />Principal Spit" Parameters: <br />Type <br />Drop Inlet <br />Drop Inlet <br />Perf. Riser <br />Perf. Riser <br />Riser Diameter (in) <br />12.0 <br />12.0 <br />12.0 <br />0.0 <br />12.0 <br />0.0 <br />Riser Height (it) <br />5,7 <br />5.5 <br />3.7 <br />-11.8 <br />3.7 <br />0.0 <br />Barrel Diameter (in) <br />18.0 <br />24.0 <br />18.0 <br />-6.0 <br />16.0 <br />0,0 <br />Elevation of Perforations) (it) <br />N/A <br />NIA <br />6583.0 <br />6583.0 <br />Size of Perforation(s) (in) <br />NIA <br />N/A <br />4.0 <br />4.0 <br />Number of Perforations <br />N/A <br />N/A <br />2 <br />2.0 <br />Emergency Spit" Parameters: <br />Type <br />Trapezoidal <br />Trapezoidal <br />Trapezoidal <br />Trapezoidal <br />Diameter (in) <br />N/A <br />NIA <br />NIA <br />N/A <br />Bottom Width (it) <br />20.0 <br />20.0 <br />20.0 <br />0.0 <br />20.0 <br />0.0 <br />Length (it) <br />40.0 <br />40.0 <br />45.0 <br />5,0 <br />50.0 <br />5.0 <br />Side Stopes'ZH: IV (it) <br />2.0 <br />3.0 <br />1.5 <br />-1.5 <br />1.5 <br />0.0 <br />HYDROLOGIC/HYDRAULIC PARAMETERS* <br />Base Flow Rates (cis) <br />1.00 <br />0.03 <br />-0.97 <br />0.15 <br />0.0 <br />10 -Year, 24 -Hour Storm Event, <br />Precipitation (in) <br />1.8 <br />1.8 <br />0.0 <br />1.8 <br />0.0 <br />Runoff Volume (ac -ft) <br />3.1 <br />117 <br />10.6 <br />4.8 <br />13.2 <br />Principal Spillway Peak Discharge (cis) <br />33 <br />6.5 <br />2.8 <br />1.6 <br />0.9 <br />Emergency Spillway Peak Discharge (cis) <br />0.0 <br />0.0 <br />0.0 <br />0.0 <br />21.5 <br />Peak Surface Water Stage Elevation (it) <br />6587.7 <br />6587.9 <br />0.2 <br />6585.1 <br />0.8 <br />25 -Year, 24 -Hour Storm Event: <br />Precipitation (in) <br />23 <br />2.3 <br />0.0 <br />2.3 <br />0.0 <br />Runoff Volume (ac -ft) <br />7,11 <br />23.3 <br />16.2 <br />14.0 <br />23.3 <br />Principal Spillway Peak Discharge (cis) <br />4.5 <br />7.6 <br />3.1 <br />5.7 <br />0.6 <br />Emergency Spillway Peak Discharge (cis) <br />3.6 <br />29.7 <br />26.1 <br />0.076.3 <br />Peak Surface Water Stage Elevation (it) <br />6588.1 <br />6588.9 <br />0.8 <br />6587.3 <br />0.8 <br />Pond Freeboard (ft) <br />1.9 <br />2.1 <br />0.2 <br />13 <br />-0.8 <br />SEDIMENT LOADING PARAMETERS: <br />Storm Predicted Peak Settlable Concentration (mlA) <br />0.00 <br />0.00 <br />0.0 <br />0.01 <br />0.0 <br />Predicted Annual Sediment Loading (ac -ft) <br />0.42 <br />0.84 <br />0.42 <br />1.30 <br />0.5 <br />Available Sediment Storage Volume (ac -ft) <br />1.27 <br />0.90 <br />-0.37 <br />0.84 <br />-0A <br />Maximum Sediment Storage Elevation (it) <br />6581.3 <br />6581.3 <br />6581.3 <br />0.0 <br />6581.3 <br />0.0 <br />Predicted Number of StoMe Years <br />10 <br />1.1 <br />-ZO <br />0.6 <br />-0.4 <br />Exh. 7 -SP -20 Revision Date: 2/1/06 <br />Revision No.: TR -63 <br />