Laserfiche WebLink
Elk Creek Mine (C-1981-022) MT-8 <br /> The topography of the region is characterized by steep canyons cut by the North Fork of the Gunnison <br /> River and its tributaries, with several remnant alluvial terraces above the valley of the North Fork. <br /> Proceeding downstream below the town of Somerset the canyon widens. At the town of Paonia, the <br /> canyon has given way to a broad alluvial plain with interspersed remnant alluvial terraces. The coal <br /> to be mined is located in the Somerset Coal Field. The strata exposed in the Somerset Coal Field <br /> consist of the Mancos Shale and the coal bearing Mesaverde Formation of Upper Cretaceous Age, <br /> and of the Ohio Creek Conglomerate, the Wasatch Formation and the Quartz Monzonite Porphyry of <br /> Early Tertiary Age. Coal is mined from the Mesaverde Formation, a 2,500 foot thick sequence of <br /> sedimentary strata overlain by the Ohio Creek Conglomerate and underlain by the Mancos Shale. <br /> The strata in the Elk Creek Mine permit area dip three to five degrees north northeast within the <br /> permit area, but varies locally. <br /> The Mesaverde Formation contains a number of coal-bearing members. The Somerset Mine mined <br /> coal from the B2-seam of the lower coal bearing (Bowie) member of the Mesaverde Formation. The <br /> Sanborn Creek and Sanborn Creek East additions mined the B-and C-seams of this member. The Elk <br /> Creek mine ramps down to the D-seam and mined that level. The Lower Coal member ranges from <br /> 260 to 350 feet thick in the Somerset Coal Field and bears three minable coal seams. This member <br /> consists of interbedded and lenticular sandstones, siltstones and coals, and is overlain by a massive <br /> sandstone, 25 to 225 feet thick which lies directly on the C-seam and marks the bottom of the upper <br /> coal member. <br /> Three categories of potential aquifers exist in the general area: alluvial deposits associated with the <br /> 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, more <br /> 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 be <br /> considered a regional bedrock aquifer. The only wells in the region which are completed in this <br /> aquifer are located near the terminated and reclaimed Hawk's Nest Mine along the North Fork. <br /> Localized perched bedrock aquifers exist in the discontinuous, lenticular, fine grained sandstones of <br /> the Upper Mesaverde Formation. The amount of ground water in these sandstones is controlled by <br /> faulting and fracturing of the strata (secondary porosity) and the topography of the recharge area. <br /> No known wells are completed in the sandstones of the Upper Mesaverde Formation above the mine <br /> workings. <br /> Page 7 of 22 <br />