2010-05-07_GENERAL DOCUMENTS - C2009087

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Table 1 - Characteristics of permeable hydrostratigraphic units in permit area and surrounding vicinity (generalized). Age Hydra Permeable lithologies Maximum Lateral extent Porosity Hydraulic Ground water Ground TDS content Potential ground stratigraphic (and depositional thickness of of permeable (total) conductivity flow velocity water type (mg/1) water use unit environment) individual beds (feet per day) permeable beds None, other than +• Coal spoil Disaggregated lower Calcium contributing to d backfill in mine member of Williams Fork 100 ft. Local >20% >10 > 5ft per day magnesium 3,800 - 4,500 stream flows via d pits Formation sulfate spoil spring fY discharges c` R c Alluvium in Poorly consolidated Calcium v O Grassy, Little deposits of clay, silt, sand, gravel, and 50 ft. o sodium Local >25% 10 > 2 ft. per day ma nesium 350 - 4,000 Domestic, stock O Grassy, and Fish boulders (stream g 2 Creeks deposits) sulfate Twentymile j Sandstone Sandstone, fine-grain, Sodium Domestic, stock, O member of well-cemented (delta front 100 ft. Regional >20% 0.4 - 10 < 50 ft. per year bicarbonate 300 - 600 irrigation Williams Fork sheet sand) v Formation d U Sandstone, very fine- C. Lower member grain, well-cemented, and Sandstone Sandstone Sodium sandstone 500 - i of Williams Fork coal (delta swamp 20 ft. Local 15-19%, 0.0001 - 4.0, < 50 ft. per year bicarbonate 2,400, coal 765 • Domestic, STOCK Formation channels, crevasse coal <10% coal 0.006 - 0.4 3,670 V , and peat bogs) splays d N Trout Creek Sandstone Sandstone, fine-grain, > 100 ft. per Sodium Domestic, stock, f well-cemented (delta front 100 ft. Regional 15-20% 3-9 ear bicarbonate 1,000 irrigation Member o lies sheet sand) y or sulfate Formation Data compiled and generalized from: PSCM and Seneca It Mine permit applications, and Geohydrologic Evaluation of the upper part of the Mesaverde Group, Northwestern Colorado (USGS Water-Resources Investigations Report 90-4020)