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~\ Premine overburden concentrations of pH, ABP, Mn, Ca, Mg, and EC are <br />compared to postmine regraded spoil values in Table 2. With the <br />exception of Mn, mean postmine regraded spoil values are more similar to <br />the lower 55 percent of the premine overburden section. Thorough <br />overburden mixing has not occurred over the entire Wolf Creek <br />reclamation area. Standard deviation values for EC, Ca, Mg, and Mn in <br />the spoil increased over premine values. Higher standard deviation <br />values indicate that both upper and lower overburden material has been <br />placed in the upper four feet of graded spoil. After comparing <br />individual sample site data from Table 1 with premine overburden data <br />from Table ?, it is evident that two unique regraded spoil areas exist <br />in the Wolf Creek reclamation area. The eastern half and western <br />one-tenth of the Wolf Creek reclamation area show evidence of upper and <br />lower overburden mixing or contain predominantly upper overburden <br />material on the regraded spoil surface (see Table 1 and Exhibit 9-4, <br />Postmine Topsoil and Spoil Sample Locations). These sites are located <br />in the deeper overburden areas (see Exhibit 6-10, Overburden Isopach). <br />The remainder of the Wolf Creek reclamation area contains predominantly <br />~' lower overburden on the regraded spoil surface. These two, different <br />reclamation areas will be monitored, evaluated, and compared for <br />revegetatiun success. <br />The highly acidic spoil (pH <5 and ABP <-5) is associated with the Wolf <br />Creek coal cropline and other shallow overburden areas (premine <br />drainages). Mitigative measures for these acid regraded spoil areas are <br />described in Geology Response 5. Excessive Mn levels (>70 ppm) were <br />only identified at five older reclamation sites that are located near <br />the Wolf Creek cropline (see Table 1). Mitigative measures are also <br />described in Geology Response 5. <br /> <br />3 <br />