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• Mean chemical values for seven additional parameters are listed in Table 2.04.6-9. No marginally <br />suitable or unsuitable values were determined for copper, lead, arsenic, zinc, nickel, cadmium, or <br />mercury. In a few instances, copper and zinc concentrations dropped below the plant deficiency <br />level. However, ample concentrations are present in the topsoil and subsoil. Since the <br />aforementioned parameters (Cu, Pb, As, Zn, Ni, Cd, and Hg) were all at nontoxic levels for Site <br />870E, they were not determined on samples collected from the remaining Phase I or Phase I I sites. <br />Mean physicochemical values for each parameter are summarized in Table 2.04.6-10 for the entire <br />New Horizon 2 study area. All mean values fall within the suitable and marginally suitable ranges <br />as outlined by the assessment criteria listed in Table 2.04.6-3. Overall, about 83 percent of all <br />overburden and interburden strata has suitable physical and chemical characteristics. <br />Sulfur fractionation analyses indicate pyrite comprises only 10 percent of the total sulfur in the <br />overburden but 45 to 85 percent in Units 2, 3, 4, and 6. Contrastingly, sulfate comprises 70 percent <br />of the total sulfur in the overburden but only 5 to 25 percent in Units 2, 3, 4, and 6. Organic sulfur <br />typically comprises between 15 and 30 percent of the total sulfur for all lithologic units. <br />• Texture and saturation percentage occasionally exceeded suitability levels in the overburden and <br />underburdenmaterial(Attachment2.04.6-3(previouslyPeabodyAppendix6-5). Theunderburden <br />predominantly consists of a very hard, indurated sandstone which typically has a sand texture and <br />low (less than 25 percent) saturation percentage. These strata will not be disturbed by mining. <br />Two lenses of white silty shale and soft brownish gray shale occur in the overburden. This strata <br />occurs in the western half of the study area (Sites 870E, 872E, 881E, and 882E) and outcrops <br />slightly east of Site 870E. The soft weathered shale strata typically has a clay texture and high <br />(greater than 85 percent) saturation percentage. Since these strata occur in thin lenses and <br />comprise only about five percent of the overburden volume, normal overburden handling by dozers <br />and scrapers will effectively blend or dilute the unsuitable clay levels to acceptable levels. <br />• REVISED August 2006 2.04.6-39 <br />