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3 <br />shales, siltstonee and sandstones with inte;-bedded coal; it is <br />the "F" seam that outcrops at an elevation approximately 6,470 <br />feet that will be extracted in the proposed ARCO mine. The dip of <br />the strata is about four degrees to the north-northeast; some <br />dips close to the seam outcrop do not agree with this regional <br />trend. Joints within the area are close to the vertical; previous <br />investigations ("Environmental Geology of the Mt. Gunnison Coal <br />Property, Gunnison County, Colorado;" Atlantic Richfield Company <br />report by S.J. Bprkheiser, dated April 1977) revealed north-south <br />and east-west orientations to be prevailing. <br />The bedrock units rarely outcrop at the site; they are <br />covered by colluvial soils and landslide deposits of various <br />thicknesses. <br />i Data on the hydrology are limited; according to the above <br />~~ referenced report it is believed that coal seams are not signifi- <br />~ cant aquifers; nor are the immediately overlying or underlying <br />it beds. Water found in the "F" seam test adit is believed to be <br />I surface water that seeps into the coal from the surface. <br />i' <br />I <br />During. the recent drilling program carried out by ARCO, <br />~ water was apparently indentified in coal in borings where stand- ~ <br />i <br />II pipe piezometers were installed. It is. not evident whether the <br />~'~ ground water occurrence is related to the exceptionally wet <br />i <br />I~ spring season of this year or whether it is permanent. As soft <br />(shales were identified immediately below coal in practically all <br />~ borings drilled on the site we suspect that the ground water in <br />~ coal is permanent and that it has contributed to the development <br />~iof landslides in the area. Except for the landslides that are <br />i;very prominent at the elevation of the coal seam outcrop there <br />I' <br />;are other signs indicating the presence of the ground water in <br />coal; there is a farming pond just at the elevation of the coal <br />seam and the .vegetation cover is different at several locations <br />~~~ indicating the local presence of springs. Ground water in sur- <br />ficial soils was also encountered in four of our test pits <br />excavated during our investigation. <br />I <br />MOW WIMA1lRK <br />