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State Reg. l underburden sample was less than 5 tons calcium carbonate per 1,000 tons of material. Significantly different pH and neutralization potentials exist between the Wolf Creek and Wadge overburden areas. The pH is 6.5 in Wolf Creek overburden and 7.9 in the Wadge overburden area. The mean acid-base potential is +1.3 in the Wolf Creek and +6.2 in the 4ladge areas. Overburden mixing will effectively mitigate many of the extreme (suspect) pH levels in individual cores. Reclamation success will be determined by treating the Wolf Creek and Wadge overburden areas independently. Since the greatest availability for the most nutrients is at a slightly acidic pH (6.5) and since trace metal availability increases exponentially at pH levels less that 5.5, spoils showing very strong acidity (pH < 5 and ABP < -5) will be limed or will receive a two to three foot suitable spoil topdressing. Nickel. Values for nickel range from < 0.3 to 9.8 ppm and have mean values of < 2.3 and < 2.5 ppm for overburden and underburden materials. Nine samples, or 7.6 percent of the total number of samples analyzed, were above 5.0 ppm suspect level. Of these, eight occurred in the overburden and one in the underburden. These strata occur in the overburden cores and comprise 9.4 to 40.0 percent of the individual core volwne (Table 6-6). Weighted mean core concentrations are less than 3.3 ppm. In most cases, high nickel concentration strata will blend with other material of lower concentration during the course of mining, and the effect will be to dilute the inimical zones. Like most other trace elements, nickel is fairly insoluble over a pH level of 6.b (Donahue, et al., 1972 and 14aclean, 1978). Wolf Creek overburden may represent a potential problem area. Liming, where necessary, (mean pH < 5 and ABP <-5) and 6-30 Revised 10/1/86