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previous Seneca II mining operations. Additional factors relative to the PHC <br />include current effluent limitations and existing wetland passive treatment <br />systems which are effective in reducing selenium. The PHC has been updated <br />to reflect current information. <br />IV. Topsoil <br />Baseline soils information is provided in Exhibit 2.04.9E-1 and on Map 2.04.9-M1 in <br />the permit application. Exhibit 2.04.13-E2 shows the thicknesses of topsoil replaced on <br />the lands that have been transferred from the Seneca II Mine permit area to the PSCM <br />permit area. The average depth was 15.6 inches as indicated by 933 samples taken over <br />1,793.acres (one sample per 1.9 acres). <br />During mining operations at the PSCM, available soil or suitable growth materials will <br />be salvaged prior to disturbing lands. Section 2.04.9 and Exhibit 2.04.9-E1 identify <br />target topsoil salvage depths. Large shrubs will be removed prior to soil removal. <br />Smaller vegetation will be removed during soil salvage and will be incorporated into <br />the topsoil as organic matter. Heavy clay soils will be recovered only if there are <br />sufficient non -clay soils loams and sandy soils for blending. <br />Approximately 140,000 cubic yards of topsoil have been salvaged during construction <br />of the PSCM portal facilities and associated roads. The salvaged topsoil has been <br />stockpiled near the PeCoCo pond in the stockpile area shown on Map 2.05.3M1A. The <br />stockpile will be seeded for erosion control with a temporary reclamation seed mix that <br />is listed in Table 24.05.4 -TI. <br />Following final grading during reclamation operations, approximately 12 inches of soil <br />will be placed on disturbed areas. The surface of the replaced topsoil will be left in a <br />roughened condition to promote infiltration, minimize runoff, and provide a good <br />seedbed for revegetation. Replaced topsoil will be stabilized by contour tilling, seeding, <br />and establishing vegetative cover soon after topsoil replacement. Replaced soil will be <br />sampled following the soil testing plan described in Section 2.05.4(2)(e)(vii) of the <br />permit application. <br />V. Sealing of Drilled Holes and Underground Openings <br />All drill holes or boreholes, wells, and portals or other underground openings will be <br />sealed to prevent acid or toxic drainage from entering the groundwater, minimize <br />disturbance to the prevailing hydrologic balance, and ensure safety. Details of the <br />sealing plan are located in Section 2.05.4(g). No variances from regular requirements <br />apply and no specific findings apply. <br />VL Use of Explosives <br />Explosives may be used occasionally, as described in Section 2.05. A certified blaster <br />will be in charge of all blasting operations to ensure compliance with state and federal <br />19 <br />