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f~ In the proposed 5-year mining area, soil and weathered bedrock vary in thickness from zero to 40 to 50 ft. The deeper weathered bedrock zones are located along the south-facing dip slope of the Coal Ridge hogback. Rock overburden. Three boreholes (Map A), distributed across the proposed permit area, were selected for analysis to determine the general statigraphy of the rock overburden above the upper and lower wheeler coal seams. The analysis was designed to determine the percentage of sandstone as well as the frequency of thick sandstone beds in the overburden section. The results of this analysis are presented in Tables 3-1 and 3-2. Geotechnical logging (Seegmiller, 1983) of a continuous core from the surface to the coal seam from test boring 3.75 (Map A) indicated that the overburden is strong and competent. Core recovery was generally greater than 90$. The RQD was generally greater than 80% and usually greater than 90%. • 3.2.2.4 Structural Geology The general structural geology of the permit area is described in Section 3.3.2 of the permit application. This section presents the pertinent aspects of the site structural geology as they relate to subsidence and surface subsidence effects. The general structural geology framework of the proposed permit area includes bedding orientation, faulting and jointing. Bedding. The proposed 5-year mining area is developed on the upturned edge of the Grand Hogback monocline, at the eastern edge of the Piceance Basin. Bedding in the proposed mining area dips from 50° to 60o and averages about 55°. Faulting. According to Collins (1976), "Considering the magnitude of the Grand Hogback structure and related features, known faulting within coal-bearing Mesaverde Group rocks is • remarkably minor." No faulting has been identified within or adjacent to the proposed permit area as a result of drilling and field geologic investigations. page 16