Laserfiche WebLink
yield enough water to function as groundwater supply wells. The West <br /> Elk Mine's permeameter tests of the Rollins Sandstone in the permit area <br /> found horizontal hydraulic conductivity values in the range 0.0001 ft/day <br /> to 0.012 ft/day. <br /> The Bowie sandstone, separating the Upper and Lower Coal Members, <br /> may produce water locally. Information from mines operating in the <br /> Lower Coal Member(i.e., Elk Creek and Bear No. 1 and No. 2 Mines) <br /> indicate this formation can yield small flows of water in the area. The <br /> unit crops out toward its down-gradient occurrence within the West Elk <br /> permit area and there are no seeps or springs emanating from the unit, <br /> demonstrating that the unit is dry in some areas. <br /> The most significant reliable occurrence of groundwater in the region is <br /> the alluvium of the North Fork of the Gunnison River. Significant <br /> thicknesses of alluvial sand and gravel between 30 and 80 feet exist <br /> along the North Fork. Numerous wells are developed in the alluvium <br /> with an average yield of 17.4 gpm. A pumping test conducted by Bear <br /> Coal Company on an alluvial well near the site of the Bear No. 3 Mine <br /> yielded a value of 806.5 gallons/day/foot for transmissivity. <br /> Three water quality analyses were conducted for the Bear No. 3 Mine on <br /> three wells completed in the North Fork alluvium. Two wells exceeded <br /> drinking water standards for total dissolved solids, sodium and sulfate. <br /> The alluvial well nearest the North Fork River channel (the Bear No. 3 <br /> office well) showed the lowest levels of these constituents. This is due to <br /> the dilution of alluvial groundwater by North Fork River water at this <br /> well. <br /> Except for areas in the Minnesota Creek Drainage, the alluvium along the <br /> lower reaches of tributaries to the North Fork is predominantly thin and <br /> confined to discontinuous narrow bands along the stream courses. The <br /> deeply incised channels of these tributaries restrict the width of the <br /> alluvium, while the stream gradient and the presence of resistant <br /> sandstone in the stream channels limit the thickness and downstream <br /> extent of the alluvium. <br /> Occurrences of groundwater have been noted in the Mesaverde <br /> Formation based upon information obtained from drilling, experience in <br /> the mines, and from the presence of springs and seeps in the region. This <br /> information also indicates that the only potential regional bedrock aquifer <br /> in the general area is the laterally continuous Rollins Sandstone. The <br /> laterally discontinuous lenticular sandstones within the Upper Mesaverde <br /> Formation support only localized groundwater flows. <br /> The Rollins Sandstone is recharged in the vicinity of the West Elk Mine <br /> by snowmelt and rainfall on outcrops, and in subcrops beneath stream <br /> alluvium and in the channels of the North Fork and its tributaries. These <br /> 38 <br />