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• These lithologic unit designations are typical for the Dakota Sandstone Formation and are similar to <br />those utilized in Mine Pit Areas 2, 3, and 5 at the New Horizon 1 mine area. The lithologic unit <br />designations for the New Horizon 2 study area are included with the lithologic descriptions in Peabody <br />Appendix 6-1. <br />Overburden, Interburden, and Underburden Suitability <br />The criteria for assessing the suitability of overburden or interburden for a root growth medium or <br />aquifer restoration material are as presented in Table 2.04.6-3. The suitability limits for each <br />parameter are documented by current literature citings. <br />The following techniques were used to analyze the Phase I and Phase II overburden, interburden, and <br />underburden sample data. Initially, statistical analyses (mean and standard deviation)were completed <br />to determine the variability between lithologic units and from core to core. Since sampling intervals <br />varied with depth, weighted means were calculated for all physicochemical parameters for each <br />lithologic unit, excluding topsoil. These means will likely be representative of the physicochemical <br />concentrations that will be present in the scraper and dozer handled spoiled overburden and <br />interburden sections. Second, the unsuitable composition for each lithologic unitwas determined and <br />• utilized to implement effective and efficient overburden and interburden handling techniques. Lastly, <br />other mitigative measures are discussed where necessary. <br />Mean physicochemical values for each parameter are listed by drill hole number and lithologic unit in <br />Tables 2.04.6-4 through 2.04.6-8. Approximately 93 percent of all mean values (239) fall within the <br />suitable and marginally suitable ranges as outlined by the assessment criteria listed in Table 2.04.6-3. <br />Exceptions include the unsuitable pH values for Unit 2 (Hole 871 E) and Unit4 (Holes 872E and 886E), <br />the unsuitable SAR for Hole 882E (Units 2, 3, and 4); and the unsuitable acid base potential values <br />for holes 870E, 871 E, 881 E, 882E (Units 2 and 4) and for Unit 4 (Holes 872E and 886E). An <br />evaluation of these unsuitable parameters is contained in the Mitigative Measures section. <br />• Revised 27 Aug 2002 24 <br />