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State Reg. <br />• Mitigation of zones with high clay content, low pH, low <br />acid-base potentials, and high nickel concentrations will be by <br />overburden mixing and chemical amendments. First, based on <br />spoil mixing phenomena (Dollhopf et al., 1978), the degree of <br />mixing can be ascertained by comparing the amount of inimical <br />material found in overburden to the amount present in the <br />resultant spoils. These results generally showed that when <br />critical parameter percentages comprise 5 to 15 percent by <br />volume of the overburden core, the parameter is blended and <br />completely diluted during the course of mining. Wolf Creek <br />overburden zone areas may occasionally require a selectively <br />handled suitable spoil topdressing or lime application if <br />surface pH levels are continuously below 5 and ABP values are <br />more negative than 5. These parameters are further discussed <br />below. <br />Clay Content. Values for clay ( < 0.002 mm soil fraction) <br />• content ranged from 1.0 to 56.0 percent and have a mean value <br />of 16.5 percent for the overburden section. Four samples, or <br />2.8 percent of the total number of samples analyzed, exceeded <br />the suspect level. These strata comprise 3.9 to 9.2 percent of <br />the individual overburden core volume (Table 6-6). Based on <br />these percentages, no inhibitory effects from clay are expected <br />at Seneca because the high clay content zones will be mixed <br />during normal spoiling operations. <br />pH and Neutralization Potential. Values for pH range from 3.6 <br />to 8.6 and have mean values of 7.2 and 7.9 respectively for the <br />overburden and underburden section. Two samples, or 1 percent <br />of the total number of overburden samples analyzed, fell within <br />the suspect range. These strata comprise 1.8 to 6.5 percent of <br />the individual overburden core volume (Table 6-6). Four <br />underburden samples had pH levels which exceeded the suspect <br />limit. The high values are attributed to high concentrations <br />• of sodium in the strata. <br />6-29 Revised 10/1/86 <br />