Laserfiche WebLink
• Snowcap Coal Company <br />Protection of the Hydrologic Balance <br />Pond 8 <br />STORM EVENTS <br />10 YEAR 24 HOUR EVENT 1.4 INCHES <br />25 YEAR 24 HOUR EVENT 1.9 INCHES <br />100 YEAR 24 HOUR EVENT 2.2 INCHES <br />r1 <br />U <br />The information presented for peak flow calculations is developed with the use of SEDCAD. <br />The output from SEDCAD follows this section. <br />The drainage areas are shown on Figure 6C, Roadside South Portal Post Mining <br />Topography. <br />The soil map, Exhibit 23 shows the soil type as 66 - "Torriorthents, Warm -Rock Outcrop" <br />and 4 "Bari Clapper complex". Generally the soil samples for this and other disturbance areas <br />indicates the soil is sandy to silty loam (Tab Section 9) which equates to a "B" soil group. Clapper <br />has a published soil group of "B" in Table B-1 of Peak Flows in Colorado. The following CN's <br />were used in the calculations: <br />Disturbed Area - 86 - B Soil Group, fallow bare soil. Used for portion of lower parking area, <br />slopes for new road <br />Asphalt - 98 - B Soil Group, bare. Used for mine bench parking area, buildings. <br />Sage Grass - 64 - B Soil Group, 20% cover. <br />Previously Disturbed - 77 - B Soil Group, medium cover. Used for reclaimed refuse <br />pile, portion of lower parking area and reclaimed slopes. <br />Gravel - 85 - B Soil Group, gravel. Used for new access road <br />RUN-OFF VOLUME - - Pond 8 <br />TOTAL REQUIRED WATER VOLUME - - A -F <br />SCC <br />RSS-1 <br />07/06 <br />Precip <br />Direct <br />Runoff <br />Area <br />Acres <br />Curve # <br />Amount <br />Runoff <br />Vol A -F <br />Asphalt <br />2.78 <br />98 <br />1.4 <br />1.18 <br />0.27 <br />Disturbed <br />5.73 <br />86 <br />1.4 <br />0.43 <br />0.20 <br />Sage Grass <br />22.67 <br />64 <br />1.4 <br />0.01 <br />0.02 <br />Prev. Disturbed <br />11.95 <br />77 <br />1.4 <br />0.17 <br />0.17 <br />Gravel <br />0.34 <br />85 <br />1.4 <br />0.39 <br />0.01 <br />TOTAL <br />43.47 <br />0.68 <br />TOTAL REQUIRED WATER VOLUME - - A -F <br />SCC <br />RSS-1 <br />07/06 <br />