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West Elk Mine <br />undrained stability was critical, while for MB-2, the consolidated drained condition was <br />critical. <br />Both a static analysis and a seismic analysis were performed for each dam embankment. For the <br />static analysis a fully saturated embankment was assumed, The seismic (or dynamic) analyses, <br />assuming the same condition, in combination, are summarized in Exhibit 44. The final run <br />for each analysis is included as a supplement to Exhibit 44. <br />HvdroloQie Protection Durine Construction <br />Early in construction, prior to the disturbance of any area for surface construction, sedimentation <br />ponds were constructed, and diversion channels to collect undisturbed surface runoff were <br />constructed to meet specific design requirements. These channels were constructed <br />coincidentally with the initial access road, and divert the runoff away from the disturbed azeas. <br />These structures were designed per Exhibit 44. Runoff is released from the sedimentation ponds <br />only after sufficient settlement of suspended solids and satisfaction of the effluent standards has <br />been achieved. Disturbance of the adjacent areas was held to a minimum. The NPDES permits <br />were secured prior to dischazging. See Exhibit 7 to this Mining and Reclamation Plan. <br />Construction practices are geared to minimize erosion in all disturbed areas (Exhibit 43). <br />During construction of the ST-4 crushed coal stack-tube and storage azea, drainage in the area <br />was diverted into the enlarged MB-3 pond so that the former ponds MB-2 and MB-6 could be <br />dried in prepazation for the construction of pond MB-2R and the coal storage area. <br />Best Management Practices (BMP) were utilized during road construction associated with the <br />Sylvester Gulch Facilities Area (PR07). BMPs were also utilized as the substation was <br />constructed. Prior to the construction of the shafts site benches, a cleaz-water diversion ditch, <br />designed to handle the peak flow from a 100-year, 24-hour storm event, was constructed. In <br />addition, prior to removing vegetation and stripping topsoil at the shafts site benches, sediment <br />pond SG-1 was constructed. The shafts site will naturally drain to the sediment pond, so life-of- <br />mine sediment ditches may not be constructed immediately, but will be established as the site is <br />developed. <br />Sediment contributions from drill sites constructed by MCC within the permit azea will be <br />minimized by cleazing the smallest azea possible, containing drilling water and cuttings in an <br />appropriately-sized pit and reclaiming the site promptly upon completion. Reclamation would <br />include grading the site, redistributing topsoil, scattering vegetative slash, seeding, and mulching, <br />if necessary. <br />a <br />2.05-32 Revised November 2004 PR70 <br />