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nitrate nitrogen, acid-base potential, manganese, iron, zinc, copper, and coal comprise 1.1 to 52.4 <br />percent of the overburden section (Tab 6, Appendix 6-51 at the sample sites. These parameters are <br />discussed in greater detail in the following section. <br />Acid- and Toxic-Forming Materials. Acid- and toxic-forming materials were identified in the Seneca II-W <br />study area as discussed in Tab 6 and listed in Tab 6, Appendices 63 and 6-5. Appropriate mitigation <br />measures such as avoidance, ameliorating reclamation techniques, or blending, dilution, andlor burial by <br />normal overburden handling, will be used to replace a suitable four-foot root growth medium, including <br />topsoil, and to prevent leachates and runoff from entering the ground water system or discharging into <br />the surface water system. No roads will be surfaced with acid-forming materials. <br />Mitigation of all unsuitable zones within the underburden material (17 percent of all 77 unsuitable zones <br />which were identified) will be by avoidance, i. e., these zones will not be disturbed by mining activities. <br />Mitigation of all unsuitable pH, saturation percentage, boron, acid-base potential, iron, zinc, copper, and <br />coal zones will be by overburden blending, dilution, and/or burial by normal overburden handling <br />techniques. All of these zones comprise 15 percent or less of the overburden section (Tab 6, Appendix <br />6-5). According to Dollhopf et al. (1978), overburden zones of unsuitable quality material will, with <br />mathematical reasoning, be acceptable material for reclamation by the spoil mixing phenomena. The <br />degree of mixing can be ascenained by comparing the amount of unsuitable overburden to the amount <br />present in the resultant spoils. These results generally showed that when critical parameter <br />percentages comprise 0 to 15 percent of the overburden core, the parameter is blended and completely <br />diluted during the course of mining. <br />Ameliorating reclamation techniques and blending, dilution, and/or burial by typical overburden handling <br />will he used to mitigate excessive levels of clay. Unsuitable clay percentages comprise less than 15 <br />percent of the overburden section at Sites 42-C, 1127-E, and 1129-E. Typical overburden handling by <br />cast blasting, dragline spoiling, and dozer grading at these three sites will effectively blend, dilute, <br />and/or bury the unsuitable clay strata. Typical overburden handling operations are described in Tab 12, <br />Coal Resource Recovery Plan and Tab 20, Backfilling and Grading. <br />2 Revised 4/24/91 <br />