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• <br />Section 779.14(a) Continued. <br />Location of Subsurface hater <br />Rule 2.04.6 <br />The primary circulation medium for numerous exploration drillholes within <br />the mine plan area was compressed air. The return air provides a rapid <br />and reliable indication of the existence of subsurface water. The only <br />significant subsurface water encountered within the strata to be disturbed <br />by the proposed mining activities was located in the Sudduth Seam. Minor <br />amounts of water were encountered with low frequency in the rock above the <br />Sudduth Seam and in the sandstone below the coal seam. <br />As discussed in Section 779.15, pump and slug tests have determined that <br />the water-bearing zones above and below the Sudduth Seam have too low a <br />permeability to be considered aquifers. Drillholes that encountered <br />groundwater were left open long enough to measure the recovered elevation <br />of the piezometric surface in eacfi hole. <br />Generally, the piezometric level is about 50 feet below the surface. <br />Additional information on groundwater occurrence and quality is presented <br />in Section 779.15. <br />Drill Hole Loos <br />Exhibit 22, Drillhole Logs, contains 88 lithologic logs which illustrate <br />and describe the lithologic characteristics and thicknesses of coal and <br />overburden strata. The location and elevation of each drillhole presented <br />in Exhibit 22, Drillhole Logs, are shown on the Kerr Mine Area Geology Map <br />(Map 6a). <br />Physical Properties of the Overburden <br />The physical properties of each lithologic type within the overburden <br />. including compaction and erodibility, but not texture, have been defined <br />by laboratory testing of representative overburden samples. The samples <br />tested were obtained as either core or chip samples from the overburden <br />drillholes shown on Table 5a, List of Drillholes Sampled for Overburden <br />Analysis. These properties are discussed in a letter from Robert 41. <br />779-15 a Revised-Anri1.149n <br />