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2001 (Exhibit 7-1A). In addition to the site specific geochemical data from WWCU- <br />24, Sage Creek/Wolf Creek overburden characterization and assessment included <br />consideration of data for the same strata from the adjacent Yoast Mine permit area. <br />Parameters sampled are listed in the permit application Volume 2, Tab 6. The permit <br />application states that these parameters were used to "document the physical and <br />chemical properties of the overburden and under burden, to compare these properties <br />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 are presented in Tables 6-4 through 6-7, and Appendices 6- <br />3 and 6-4 of Tab 6. Analytical data associated with Wolf Creek and Sage Creek <br />overburden and underburden are 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 />Wadize Overburden/Underburden Assessment <br />In 4% or less of the samples analyzed, pH, acidibase 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 Mine <br />Overburden in Montana" (Chapter 5, Summary Report, 1981) suggests that if the <br />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 />Two primary concerns identified by the Division as a part of the PR -1 review were <br />in regard to potentially acid-forming materials associated with the Lennox coal seam <br />and excessive clay contents associated with shale strata overlying the Lennox. The <br />Division requested SCC to prepare a spoil sampling plan and mitigation plan for <br />areas where the Lennox would be spoiled, and for areas where the Lennox would <br />potentially be exposed by high wall reduction. A more detailed mitigation plan for <br />areas of excessive clay content was also requested. <br />SCC submitted an acceptable sampling plan to be employed in areas potentially <br />affected by Lennox spoil or outcrop within the original permit area. The same <br />sampling plan was to be applied to all regraded spoil areas and graded final high <br />walls in the south extension mining block. The plan called for samples to be taken <br />on 500 -foot centers within the designated area, and analyzed for clay content, pH, <br />and acid-base potential. Mitigation was to include additional sampling to define the <br />area of concern, deep ripping of areas of unsuitable clay content, and amendment or <br />burial of acid-forming material with a minimum of four feet of suitable material as <br />9 <br />