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prior to initiation of operations. Additional drilling and sampling was conducted <br />within the south extension area in 1991. Until approval of PR -3, in 2003, coal <br />extraction was limited to the Wadge seam, and the initial baseline studies were <br />focused on Wadge overburden assessment. Strata from the surface to immediately <br />below the Wadge coal seam were sampled. Core holes were distributed across the <br />Wadge recovery areas in both the original permit area and south extension area <br />(Exhibits 6 -6 and 6 -6A). <br />PR -3 allowed for surface mining of the Sage Creek and Wolf Creek Seams, as well <br />as the Wadge, within the South Extension area. Characterization and assessment of <br />Sage Creek and Wolf Creek overburden, and Wolf Creek underburden was based on <br />chip samples collected from Monitoring Well WWCU -24, which was drilled into the <br />Wolf Creek underburden near the western boundary of the south extension area in <br />2001 (Exhibit 7 -1A). In addition to the site specific geochemical data from <br />WWCU -24, Sage Creek/Wolf Creek overburden characterization and assessment <br />included consideration of data from the adjacent Yoast Mine permit area, for the <br />same strata. <br />Parameters sampled are listed in the permit application Volume 2, Tab 6. The <br />permit application states that these parameters were used to, "document the physical <br />and chemical properties of the overburden and underburden, to compare these <br />properties to ground water quality, and to determine potential reclamation success." <br />The data obtained from the geochemical analyses were compared to criteria derived <br />from State and Federal agencies (USDA, BLM, Wyoming DEQ, and others). The <br />criteria used for comparison and relative degrees of suitability are listed in Volume <br />2, Tab 6, Table 6 -3. Analytical data associated with Wadge overburden and <br />immediate underburden is presented in Tables 6 -4 through 6 -7, and Appendices 6 -3 <br />and 6 -4 of Tab 6. Analytical data associated with Wolf Creek and Sage Creek <br />overburden and underburden is presented in Tables 6 -7A through 6 -7D, and <br />Appendix 6 -3 of Tab 6. Summary tables and text delineating unsuitable zones and <br />addressing mitigative measures for unsuitable zones within Wadge, Wolf Creek and <br />Sage Creek overburden and underburden are included in Appendix 6 -5. <br />Wadge Overburden/Underburden Assessment <br />In 4 % or less of the samples analyzed, pH, acid /base potential, boron, manganese, <br />cadmium and zinc exceeded suspect levels. In general, the Division concurs with <br />the applicant's determination that normal mixing of overburden will mitigate the <br />toxic effects of these materials. D.J. Dollhopf in "Selective Placement of Strip <br />Mine Overburden in Montana" (Chapter 5, Summary Report, 198 1) suggests that if <br />the volume of toxic material is less than 15 % of the total volume of material to be <br />replaced, dilution of the toxic material can be successful. <br />Seneca II -W Findings Document 23 C- 1982 -057 <br />Permit Revision No. 6 January 6, 2012 <br />