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Stability Analysis <br />Various soil states were investigated to determine the most critical condition for each embankment. <br />The unconsolidated undrained condition, the consolidated undrained condition, and the <br />consolidated drained condition were considered for all embankments. In the case of MB-1 and FW- <br />1 for the clay material embankment the consolidated undrained stability was critical, while for MB- <br />2 the consolidated drained condition was 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) analysis <br />assumed the same condition in combination with a seismic analyses are summarized in Exhibit 44. <br />The fmal run for each analysis is included as a supplement to Exhibit 44. <br />Eazly 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 coincidentally <br />with the initial access road, and divert the runoff away from the disturbed areas. These structures <br />were designed per Exhibit 44. Runoff is released from the sedimentation ponds only after sufficient <br />settlement of suspended solids and satisfaction of the effluent standazds has been achieved. <br />Disturbance of the adjacent azeas was held to a minimum. The NPDES pemuts were secured prior <br />to dischazging. See Exhibit 7 to this Mining and Reclamation Plan. Construction practices aze <br />geared to minimize erosion in all disturbed azeas (Exhibit 43). <br />During construction of the ST-4 crushed coal stacktube and storage azea, drainage in the azea was <br />diverted into the enlazged MB-3 pond so that the former ponds MB-2 and MB-6 could be dried in <br />preparation for the construction of pond MB-2R and the coal storage azea. <br />Best Management Practices (BMP) will be utilized during road construction associated with the <br />Sylvester Gulch Facilities Area (PR07). BMPs will also be utilized as the substation is constructed. <br />Prior to the construction of the shafts site benches, a cleaz-water diversion ditch, designed to handle <br />the peak flow from a 100-yeaz, 24-hour storm event, will be constructed. In addition, prior to <br />removing vegetation and stripping topsoil at the shafts site benches, sediment pond SG-1 will be <br />constructed. The shafts site will naturally drain to the sediment pond, so life-of--mine sediment <br />ditches may not be constructed immediately, but will be established as the site is developed. <br />Sediment contributions from drill sites constructed by Mountain Coal Company within the pemut <br />azea will be minimised by clearing the smallest azea possible, containing drilling water and cuttings <br />in an 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, if <br />necessary. <br />2.05-36 Revrsed Nov. 1996 PR07; Revised Jun. 1999 TR90 <br />