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1.5-foot thick shale zone directly oven yi ng the cadge coal seam. Peabody suspected the • <br />excessive iron and manganese values from the Phase 1 drilling were attributed [o the core <br />samples having been contaminated by drill st em grease. This hypothesis was confirmed by <br />the Phase II overburden analyses. Phase II iron and manganese values were three times <br />less then the Phase 1 values. The few unsuit able zinc concentrations ere limited to areas <br />that will be avoided or occur in the Nolf Creek coal recovery area. one of the two <br />unsuitable molybdenum values occurs in the underburden at Site 2315E, while the other <br />occurs in the neck area et Site 2376E. <br />wo unsuitable concentrations were recorded for selenium, lead, nickel, copper, or cadmium. <br />The maximum veLues recorded for feed, selenium, and cadmium are an order of magnitude less <br />then the threshold limit, while values for nickel and copper are about two to five times <br />less than threshold limits. No unsuitable values were recorded for salinity; however, <br />maximum veLues were less than two times the threshold value. <br />The following techniques were used [o analyze the overburden and underburden sample data. <br />Initially, statistical analyses (mean end standard deviation) were completed to determine <br />the variability between overburden and underburden, and from core to core. Since sampling • <br />intervals varied with depth, weighted means were calculated for all physiochemical <br />parameters across ell lithology types, excluding topsoil. These means, calculated for <br />each core site, will likely be representative of the phys iothemical concentrations that <br />will be present in the dregline, dozer, end scraper handled spoiled overburden. Second, <br />the unsuitable composition for each core was determined and utilized to implement <br />effective and efficient overburden handling techniques. Lastly, other mitigative measures <br />are discussed where necessary. <br />Mean physiochemical values for each overburden end underburden parameter ere listed by <br />bore and tore hole number in Tables 6 end 7. About 99.5 percent of ell mean values fell <br />within the suitable and marginally suitable ranges as outlined by the assessment criteria <br />listed in Table 5. Exceptions include the unsuitable overburden manganese concentration <br />for Site 2317E (90.6 ppm) end the unsuitable underburden acid base potential for Site <br />2373E (-11.6 tons calcium carbonate per 7000 tons of underburden). An evaluation of all <br />unsuitable parameters is contained in the Acid- end Toxic-Forming Materiels section of Teb <br />27. There is also appreciable variability for the following parameters within the two <br />geologic sections across the entire study area. Saturation percentages, boron values, • <br />conductivities, end clay percentages are ell about 50 percent higher in the thicker <br />28 Revised 03/01/95 <br />