GENERAL31415 - Laserfiche WebLink

Home Browse Search

-24- The most significant occurrence of ground water in the region is associated with the alluvium of the North Fork of the Gunnison River. Significant thicknesses of alluvial sand and gravel between 30 to 80 feet exist along the North Fork. Numerous wells are developed in the alluvium with an average yield of 17.4 gpm. The Terror Creek Loadout draws 450 gpd from the alluvium of the North Fork of the Gunnison. 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 g/ft/d for transmissivity and 0.2 for storativity. 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 well located closest to the North Fork (the Bear No. 3 - office well) showed the lowest levels of these constituents. This is due to the dilution of alluvial ground water by North Fork River water at this well. Except for areas in the Minnesota Creek Drainage, the alluvium along the lower reaches of tributaries to the North Fork is predaninantly thin and confined to discontinuous narrow bands along the stream courses. The deeply incised channels of these tributaries restrict the width of the alluvium, while the stream gradient and the presence of resistant sandstone in the stream channels limit the thickness and extent of the alluvium. One mine in the region draws water from the alluvium of tributaries to the North Fork; the Orchard Valley Mine draws water from the alluvium of Steven's Gulch. Pumping tests conducted by CWI at the Orchard Yalley Mine indicate that the Steven's Gulch alluvium could support a pumping rate of 28 gpm. Transmissivity ranges from 187-230 ft2/day. Terror Creek may have alluvial/colluvial aquifers that could be developed as water supplies. However, no detailed analysis of this alluvium has been conducted. The Terror Creek alluvium may be used as a source of water at the Morrell Cow Camp to the north of the Orchard Valley Mine. When the Blue Ribbon Mine was in operation, it utilized alluvial waters from Hubbard Creek. Water quality analysis for the Steven's Gulch well water indicates good quality water, with none of the parameters exceeding the recommended drinking water standards. Observations made underground by the staff of the Division at the Blue Ribbon, Hawk's Nest, Mt. Gunnison, Somerset and Orchard Valley Mines indicate that the coal seams in the region are poor aquifers with very low transmissivities. The "B-2", "E" and "F" seams were observed to weep slightly at fresh cut faces, while mine entry walls a short distance from the face were dry. The sandstone and siltstone roof strata in the Blue Ribbon, Hawk's Nest and Somerset mines also weep for short periods of time following mining and eventually dry up. The Hawk's Nest Mine workings in the "E" seam are dry even though these workings are within 600 feet of the North Fork, are below the level of the North Fork, and are parallel to the North Fork. These in-mine observations indicate that the "6-2", "E" and "F" coal seams and their roof strata are not significant regional aquifers. Observations of mining within the "C" seam at the Bear o. 1 and No. 2 mines and of mining within the "D" seam at the Orchard Valle Mine indicate that the "C" and "D" seams and their associated roof strata also are not significant regional aquifers. If the coals and their roof strata were aquifers, these strata would have continued to weep throughout the life of these mines.