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All overburden of poor to unsuitable quality has been identified in Appendix 6-4, <br />Tables 5 through 13. The increments identified included poor to unsuitable zones of <br />clay, sodium, manganese, nickel, zinc, lead, cadmium, nitrate, pH, and acid-base <br />potential. All poor to unsuitable quality under burden will not be disturbed during <br />mining. These azeas were mitigated by avoidance. Regraded spoil from the Lennox <br />highwall reduction azea was sampled on a 300-foot grid and tested for sodium. <br />Exposed sodic strata was either buried in the fmal pit or covered with two to three <br />feet of suitable spoil. Several of the poor to unsuitable zones represent less than 15 <br />percent of the overburden volume. These areas were mitigated by mixing. This <br />includes all unsuitable clay, nickel, zinc, lead, cadmium, pH and acid-base potential <br />zones. <br />Spoil sampling is concentrated in the Wolf Creek reclamation azea. Spoil was <br />sampled on a 300-foot grid prior to soil redistribution and analyzed for pH, EC and <br />acid-base potential. A selectively handled suitable spoil top dressing or lime <br />application was made where acid strata is encountered. Sampling was focused on <br />the high clay areas. The spoil was deeply ripped or chiseled plowed where"clay <br />strata exist on the spoil surface. <br />Pursuant to 4.05.8(3), temporary storage of acid or toxic forming spoil may exceed <br />30 days if the operator demonstrates that burial or treatment is not feasible within 30 <br />days due to weather conditions or other specified factors, and will not result in <br />material risk of water pollution or other environmental damage. If deemed necessary <br />by the Division based on the quantity, location, and chemical characteristics of any <br />temporazily stored acid-forming or toxic-forming spoil, such spoil was placed on <br />impermeable material. <br />E. Surface and Ground Water Monitoring <br />Ground Water <br />Ground water hydrology information can be found in Volumes 4, 5, and 6, Tab 7 of <br />the permit application, and in the Annual Hydrology Reports submitted by Seneca <br />Coal Company. <br />An extensive ground water monitoring program which was in existence prior to <br />1981, has identified five aquifers at or neaz the Seneca II Mine site: (1) Trout Creek' <br />Sandstone member of the Mesaverde Group, (2) Wolf Creek Coal, (3) Wadge Coal <br />and Overburden, (4) Quaternary alluvium, and (5) replaced spoils. Ground water " <br />monitoring well locations are shown on Exhibit 7-2 in Che permit application. ., <br />With the exception of the Quaternary alluvium and replaced spoils, it is thought-that <br />each of the identified aquifers aze hydraulically discontinuous with each other:' This <br />17 <br />