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2.04.5 General Description of H~droloPy and Geology <br />The mine is on the northern edge of the San Juan Basin which extends over thousands <br />of square miles in Colorado and New Mexico. The upper Cretaceous strata outcrops in <br />parts of the mine and locally dips 26 to 30 degrees to the southeast. This same strata <br />can be found several thousand feet deep in other parts of the basin. A surface geology <br />map of the Carbon Junction area has been included (See Map 4-2). Oakridge has <br />provided a substantial amount of geological information in Appendices 4-2, 4-2a,4-2b, <br />and 4-3. The reader is referred to these appendices for a complete support knowledge <br />of the general and specific geology of the mine and permit area. <br />The mine permit area covers the upper reaches of potential recharge areas of basin <br />strata. Hydrology extrapolations indicate the main recharging for the aquifers occurs <br />from the Animas River which is up to 800 feet difference in elevation. Generally, <br />minute infiltration will occur in upland areas, such as the mine, and discharge to the <br />level of the river. The mine permit area occupies an infinitesimal area of potential <br />infiltration of water. The project will not significantly disrupt any flows or streams in <br />the general hydrologic area surrounding the mine because Carbon Junction Canyon <br />flows only intermittently. <br />While drilling exploration holes, on-site drillers and geo]ogists identified inflows of <br />. water in the discharge from drilling fluids. The amounts of water encountered were <br />noted along with the interval and strata from which the water apparently originated. <br />Field observation and testing during and subsequent to drilling indicate that water was <br />encountered at the following locations: <br />1) Fractured coal seams, <br />2) Interfaces of coal and overburden, <br />3) Fractured woes <br />These observations also confirm that no additional water was encountered from the <br />sandstone members in the mine vicinity. More specifically, Holes 12B, 17B and 82-5 <br />penetrated the Pictured Cliffs Sandstone which is of particular concern to the Division. <br />No water inflows was identified in the above mentioned holes. <br />The Pictured Cliffs Sandstone was examined as a potential aquifer. Consequently, <br />attempts have been made by the permittee to determine values relative to storativity (S) <br />and transmissivity (T), which are qualifications valuable in the determination of the <br />relative potential of an aquifer. See the information in Appendix 4-3a for a detailed <br />analysis of the subject sandstone. The S and T values are particularly useful in <br />assessing potential of high-flow water wells. However, where low flows and non- <br />homogeneous materials aze encountered, the T and S values are of little value, <br /> <br />Technical Revision 09 (v 1.0) 4-4 Revised 3/1998 <br />