Laserfiche WebLink
I <br />~ s <br />1 ~ shales, siltstones and sandstones with interbedded 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 />i <br />Coal <br />i <br />ti <br />ti <br />i <br />t <br />l <br />f th <br />Mt <br />("E <br />l G <br />G <br /> son <br />nves <br />ga <br />ons <br />nv <br />ronmen <br />eo <br />ogy o <br />. <br />unn <br />a <br />e <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 /> <br /> The bedrock units rarely outcrop at the site; they are <br /> covered by colluvial soils and landslide deposits of various <br /> i <br />thicknesses. <br /> Data on the hydrology are limited; according to the above <br /> referenced retort it is believed that coal seams are not si6nifi- <br />' _~ i ~ cant aquifers; nor are the immediately overlying or underlying <br />i beds. Water found in the "F" seam test adit is believed to be <br /> surface water that seeps into the coal from the surface. <br /> During the recent drilling program carried out by ARCO, <br /> <br />water was apparenCly indentified in coal in borings where stand- <br />s <br /> pipe piezometers were installed. It is not evident whether the <br /> ground water occurrence is related to the exceptionally wet <br /> ~~ 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 /> of landslides in the area. Except for the landslides that are <br /> suety prominent at the elevation of the coal seam outcrop there <br />B <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 />' <br /> m.~.nocewuvw .¢ <br />