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State Reg. 4.0 Poor to Unsuitable Material All overburden of poor to unsuitable quality has been identified in Appendix 6-4, Tables 5 through 13. The increments identified included poor to unsuitable zones of clay, sodium, manganese, nickel, zinc, lead, cadmium, nitrate, pH, and acid-base potential. 4.1 Mitigative Measures AT1 poor to unsuitable quality underburden will not be disturbed during mining. This includes many of the sodic and acidic strata identified in Tables 4 and 13. These zones will be mitigated by avoidance. AT1 unsuitable zones (clay and sodium) associated with Core Hole 2614E will also be mitigated by avoidance. The Wadge Coal seam is 171 feet deep at this location and will not be mined. However, sodic overburden may be encountered where the Lennox coal seam is intercepted as the final highwall is reduced. Regraded spoil from the Lennox highwall reduction area (in the immediate vicinity of Drill Hole Site 2614E) will be sampled on a 300-foot grid and tested for sodium. Exposed sodic strata will either be buried in the final pit or covered with two to three feet of suitable spoil. Many of the poor to unsuitable zones represent less than 15 percent of the overburden core volume. These zones will be mitigated by mixin This includes all unsuitable clay (except at Core 2034E), nickel, zinc, lead and cadmium zones, and many of the pH and acid-base potential zones. Manganese levels in the Wolf Creek area near Core Holes 2438E and 2334E will be monitored when the regraded spoil is sampled for pH and ABP levels. These zones will be mitigated by sampling, chemical amendments and/or selective handliny. Selective dragline handling techniques (mixiny, segregating/burying acid strata, and/or segregating/to pdressing ~ with suitable material) will be monitored to evaluate their effectiveness in eliminating unsuitable pH and ABP levels at 6-153 Revised 10/1/86