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Inter-Mountain Laboratory (IML) in Sheridan, Wyoming for analysis. The soil analyses methods are listed in Table 91.1. The location of each spoil pit is shown on the 1"-400' scale existing topography map, Exhibit 91.2, 1991 Soil and Spoil Monitoring Map. Coordinate and elevation data, provided by the Seneca Mine Engineering Department, and field description data are on file at Peabody's Western Division office in Flagstaff, Arizona. Laboratory results for spoil samples collected from the 29 Wolf Creek mining area 6ackhoe pits are presented in Attachment 91.2. Thirty percent of the area had been topdressed (subsoiled) and ten percent soiled before sampling. Three types of Wolf Creek spoil were identified during [he 1991 sampling program. A yellowish brown, grayish brown, or brown neutral (pH = 6.8) Spoil was identified at sampling locations WC-132, WC-133, WC-134 (0-2'), We-136 (0-3'), WC-138 (0-1~), WC-144 (0-1.5'), WC-146, WC-149, and WC-160 where a topdressing of subsoil had been replaced by scraper or dragline and dozer. The subsoil replacement area for the 1991 field season is shown on Exhibit 91.2. The subsoil has suitable salinity (EC = 1.6 mmhos/cm) and typically has a slight excess of carbonates (ABP = 6.3 TCaC03/10007 spoil). This subsoil has characteristics similar to the fractured, highly weathered, oxidized, fine grained sandstone found in the upper overburden section. Brown, grayish brown, and very dark grayish brown, slightly acid (pN = 6.5) spoil was identified at sampling locations WC-134 (2-4'), WC-135, WC-136 (3-4'), WC-137, WC-139 through WC-143, WC-144 (1.5-4'), WC-145, WC-147, WC-148, WC-150 through WC-156, and WC-159 where the spoil uas tasted and graded by standard dragline and dozer techniques. This mixed spoil has suitable salinity (EL = 3.2 mmhos/cm) and typically contains a slight excess of carbonates (ABP = 7.1 TCaC03/10007 spoil). Spoil mixing by standard dragline and dozer techniques at these moderately deep to deep overburden sites has been sufficient to blend and dilute or bury unsuitable acidic overburden strata. a very dark grayish brown and dark gray, strongly acid (pH = 5.4) spoil was identified at sites 138 (1-4'), WC-157, and WC-158. This spoil has a calcium carbonate (CaC03) deficiency of 8.4 tons per 1000 tons of spoil. The spoil has suitable salinity (EC = 4.8 mmhos/cm) values that are moderate and within acceptable limits (see Seneca II Mine PAP, ., Tab 6, Table 6-3)- A very low pH level of 3-9 was identified at site WC-135; however, normal root growth to a depth of 2.6 feet was identified. Unsuitable ABP values were 7