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Unsuitable clay strata comprise 18.6 to 52.4 percent of the overburden section at Sites 43-C, 99-C, <br />508-C, 1128-E, and 1130-E. The excessive clay values are associated with the shaley overburden <br />strata that overlies the Lennox coal seam. Because these elevated clay levels are found in the upper <br />half of the overburden section, SCC anticipates the material will be buried by typical overburden <br />handling operations and will occupy the central portion of the backfilled spoil profile. Cast blasting will <br />be used to fracture the consolidated overburden. During cast blasting, part of the lower half of the <br />overburden consisting predominantly of hard sandstone, will likely be projected into the adjacent pit. <br />The shaley overburden will then be uncovered by the dragline and placed over the sandstone rubble. <br />Lastly, the shaley spoil will be covered by the remaining fractured sandstone. <br />Typical overburden handling will be used to blend, dilute, or bury strata with unsuitable nitrate levels. <br />Blending and dilution will be effective at Sites 1127-E, 1129-E, and 1130-E where unsuitable nitrate <br />strata comprise 73.8, 4.2, and 7.2 percent, respectively, of the overburden section. Excessive nitrate <br />levels were identified in 45 percent of the overburden at Site 7128-E, mostly in the upper 65 feet. <br />Typical overburden handling will effectively bury this strata in the central portion of the spoil profile. <br />SCC also believes chat sampling error limproper sample handling or sample contamination from drilling <br />additives) may have contributed to the excessive nitrate levels identified in the 1981 overburden cores. <br />Nitrate contamination problems were also identified for three overburden cores that were collected in <br />August and September 1981 from the Seneca !I Mine (Peabody Coal Company, 1986). <br />Typical overburden handling will be used to blend, dilute, or bury strata with unsuitable manganese <br />levels. Blending or dilution will be effective at Site 1128-E where unsuitable manganese strata <br />comprised 5.1 percent of the overburden section. Excessive manganese levels were identified in 30 <br />percent of the overburden at Site 1127-E, mostly in the upper 13 feet. Typical handling will effectively <br />bury this strata in the central portion of the spoil profile. Like most trace elements, manganese is fairly <br />insoluble over a pH of 6.0. Manganese stability is expected in the spoil pile because of the neutral <br />reaction and excess carbonates. <br />Regraded Spoil Monitoring Program. In order to provide a feedback system to check the reliability of <br />the overburden sampling and analysis program, a regraded spoil monitoring program will be initiated. <br />A sampling plan will be used near the Lennox Coal outcrop as <br />3 Revised 4/24/91 <br />