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2.4 CONTROL FACTOR, C <br />The Control factor is used to account for vegetative or mulch cover. The following values presented in <br />Table 3 were utilized in previous pond design evaluations (Schwab and Warner, 1987): <br />TABLE 3 <br />CONTROL FACTOR <br />COVER <br />COVER TYPE <br />VEGETATION <br />CONTROL <br />Undisturbed <br />Sagebrush (fair) <br />none <br />FACTOR <br />Disturbed <br />Topsoil Stripped <br />No appreciable canopy or cover <br />1.00 <br />Undisturbed <br />Sagebrush (fair) <br />50%canopy (2.0 m fall height), 40% <br />0.070 <br />Disturbed <br />Topsoil Stripped <br />ground cover <br />0.9 <br />Mountain Shrub <br />75% canopy (0.5 m fall height), <br />0.080 <br />40% ground cover <br />Juniper* <br />n/a <br />0.100 <br />* A conservatively high value of 0.100 was assigned for Juniper <br />2.5 PRACTICE FACTOR. P <br />The practice factor is used to account for conservation practices for the watershed. <br />Presented in Table 4 were utilized in the pond design evaluations (Renard et al, <br />Warner, 1987): <br />TABLE 4 <br />PRACTICE FACTOR <br />SURFACE <br />SURFACE TYPE <br />PRACTICE <br />CONTROL <br />FACTOR <br />Undisturbed <br />Sagebrush (fair) <br />none <br />0.9 <br />Mountain Shrub <br />none <br />0.9 <br />Juniper <br />none <br />0.9 <br />Disturbed <br />Topsoil Stripped <br />none <br />0.9 <br />2.6 SEDIMENT PARTICLE DISTRIBUTION <br />The following values <br />1996) (Schwab and <br />SEDCAD4 requires the particle size distribution of the erodible material be entered. A general <br />particle size distribution was developed based on the weighted average of physical analysis data <br />results from the mine areas. The following particle size distribution was agreed upon between the <br />DMG and Colowyo: <br />Sand <br />27 percent <br />Silt <br />40 percent <br />Clay <br />33 percent <br />The resulting sediment distribution is shown on the SEDCAD4 printouts. <br />3.0 POND GEOMETRY INPUT PARAMETERS <br />Pond dimensions and input parameters were obtained from scaled drawings generated with AutoCAD <br />design software which utilized 25 -foot contour interval topography generated by aerial survey. The pond <br />dimensions are an approximation and will be updated upon the completion of final grading. Absolute <br />elevations are likely to charge due to more accurate topographic information, but relative elevations (dam <br />Exh. 7-23-5 Revision Date: 9/23/11 <br />Revision No.: PR -03 <br />