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C- 1981 -022 <br />PR -7 Findings <br />October 4, 2012 <br />Somerset Coal Field consist of the Mancos Shale and the coal- bearing Mesaverde Formation of <br />Upper Cretaceous Age, and of the Ohio Creek Conglomerate, the Wasatch Formation and the <br />Quartz Monzonite Porphyry of Early Tertiary Age. Coal is mined from the Mesaverde <br />Formation, a 2,500 foot thick sequence of sedimentary strata overlain by the Ohio Creek <br />Conglomerate and underlain by the Mancos Shale. The strata in the Sanborn Creek and Elk <br />Creek Mines permit area dip three to five degrees north- northeast within the permit area, but <br />varies locally. <br />The Mesaverde Formation contains a number of coal - bearing members. The Somerset Mine <br />mined coal from the B -2 seam of the lower coal bearing (Bowie) member of the Mesaverde <br />Formation. The Sanborn Creek and Sanborn Creek East additions mined the B and C seams of <br />this member. The Elk Creek mine ramps down to the D -seam and will mine that level. The <br />Lower Coal member ranges from 260 to 350 feet thick in the Somerset Coal Field and bears <br />three minable coal seams. This member consists of interbedded and lenticular sandstones, <br />siltstones and coals, and is overlain by massive sandstone 25 to 225 feet thick which lies directly <br />on the C seam and marks the bottom of the upper coal member. <br />Three categories of potential aquifers exist in the general area: alluvial deposits associated with <br />the North Fork of the Gunnison River and its tributaries, the Rollins Sandstone, and lenticular <br />discontinuous sandstones of the Upper Mesaverde Formation. <br />The largest alluvial aquifers are associated with the North Fork of the Gunnison River. Smaller, <br />more isolated alluvial aquifers are associated with several tributaries of the North Fork. <br />The Rollins Sandstone is the only known sandstone with sufficient porosity and lateral extent to <br />be considered a regional bedrock aquifer. The only wells in the region which are completed in <br />this aquifer are located near the Hawk's Nest Mine along the North Fork. <br />Localized perched bedrock aquifers exist in the discontinuous, lenticular, fine - grained sandstones <br />of the Upper Mesaverde Formation. The amount of ground water in these sandstones is <br />controlled by faulting and fracturing of the strata (secondary porosity) and the topography of the <br />recharge area. No known wells are completed in the sandstones of the Upper Mesaverde <br />Formation above the mine workings. <br />The valley in which the towns of Paonia and Somerset are situated is semi -arid, with annual <br />precipitation averaging about 15 inches per year. Mean annual precipitation increases with <br />elevation, reaching over 40 inches per year near the summit of Mt. Owen. The May to <br />September precipitation is five inches for the lowlands and 13 inches for the mountain peaks. <br />This indicates that snowfall patterns play an important part in determining the hydrologic <br />conditions of the area. Temperature extremes at Paonia have ranged from —28 °F in January to <br />100 °F during July and August. The average annual temperature is approximately 49 °F. <br />Snowfall averages 58 inches per year. <br />The general area in which the Elk Creek / Sanborn Creek Mines are located is characterized by <br />10 <br />