2018-09-04_GENERAL DOCUMENTS - C1980007

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39 creeks tributary to the North Fork; 3) the discontinuous, lenticular and laminar sandstones of the Mesaverde Formation; 4) the Rollins Sandstone; 5) the coal seams; 6) shallow colluvial surficial deposits; and 7) fracture zones in bedrock. The most laterally continuous sandstone units in the region are the Rollins Sandstone and the massive sandstone separating the Upper and Lower Coal Members of the Mesaverde Formation, known as the Bowie Sandstone. The Rollins crops out in the South of Divide area, approximately one mile upgradient from the West Elk Mine’s underground workings. In the Jumbo Mountain area, the Rollins Sandstone appears to be hydraulically isolated. To the south and west, the Rollins Sandstone crops out in cliffs. In the Jumbo Mountain area, the average interburden thickness between the B Seam and the Rollins Sandstone is 150 feet. The Rollins Sandstone has been considered a hydrostratigraphic unit of potential regional importance, because of its wide areal extent in the southeastern Piceance Basin. The Rollins is a poor quality aquifer due to its low permeability and poor water quality. A pump test of the Rollins Sandstone near the West Elk Mine yielded 3 gallons per minute. Drillholes in the Rollins in the vicinity of the Bowie #1 Mine did not yield enough water to function as groundwater supply wells. The West Elk Mine’s permeameter tests of the Rollins Sandstone in the permit area found horizontal hydraulic conductivity values in the range 0.0001 ft/day to 0.012 ft/day. The Bowie sandstone, separating the Upper and Lower Coal Members, may produce water locally. Information from mines operating in the Lower Coal Member (i.e., Elk Creek and Bear No. 1 and No. 2 Mines) indicate this formation can yield small flows of water in the area. The unit crops out toward its down-gradient occurrence within the West Elk permit area and there are no seeps or springs emanating from the unit, demonstrating that the unit is dry in some areas. The most significant reliable occurrence of groundwater in the region is the alluvium of the North Fork of the Gunnison River. Significant thicknesses of alluvial sand and gravel between 30 and 80 feet exist along the North Fork. Numerous wells are developed in the alluvium with an average yield of 17.4 gpm. A pumping test conducted by Bear Coal Company on an alluvial well near the site of the Bear No. 3 Mine yielded a value of 806.5 gallons/day/foot for transmissivity. Three water quality analyses were conducted for the Bear No. 3 Mine on three wells completed in the North Fork alluvium. Two wells exceeded drinking water standards for total dissolved solids, sodium and sulfate. The alluvial well nearest the North Fork River channel (the Bear No. 3 office well) showed the lowest levels of these constituents. This is due to