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-34- <br />Occurrences of ground water have been noted in the Mesa Verde Formation from information <br />obtained from drilling, experience in the mines and from the presence of springs and <br />seeps in the region. This information also indicates that the only potential <br />regional aquifer in the area is the laterally continuous Rollins Sandstone. The <br />laterally discontinuous lenticular sandstones within the Mesa Verde Formation support <br />only localized ground water flows. Recharge to the Rollins Sandstone occurs along <br />outcrops and along subcrops beneath the alluvium and along the channels of the <br />North Fork and its tributaries. However, due to the steepness of the topography in <br />the outcrop areas (i.e., sandstones are cliff formers) and the narrowness of the stream <br />valleys, the Rollins Sandstone receives little recharge. Some recharge to this <br />continuous unit may come directly from the percolation of snowmelt and precipitation <br />downward through faults and fractures. Drill holes which penetrated the Rollins <br />Sandstone near the Orchard Valley mine were initially dry, but after allowing these <br />holes to recover they accumulated water, sometimes as much as 300 gallons. However, <br />this amount of water is insufficient to provide a desirable well yield. This indicates <br />that recharge along outcrops and subcrops above the level of the North Fork is <br />insufficient to sustain ground water wells developed in the Rollins. The only domestic <br />use of the water from the Rollins Sandstone is from wells along the North Fork near <br />the Hawk's Nest mines. The water quality elsewhere is considered too saline for <br />domestic use (Price and Arrow, 1974; Iornes et. al., 1965). <br />Preliminary aquifer tests were performed (by ARCO) on the Barren Member of the Mesa Verde <br />Formation in September, 1974. The preliminary transmissivity obtained for this member <br />was calculated to be 2.46 g/d/ft. Also, ARCO performed a preliminary aquifer test <br />on the "F" seam which yielded a transmissivity of 16.68 g/d/ft. These aquifer tests <br />indicate that the "F" seam and the lenticular sandstones of the Barren Member are <br />poor aquifers at best. Observations made underground by the staff of the Division at <br />the Blue Ribbon, Hawk's Nest, Mt. Gunnison and Somerset mines also indicate that <br />the coal seams are poor aquifers with very Low transmissi vi ti es. The "B-2", "E" <br />and "F" seams were observed to weep slightly at fresh cut faces, while entry walls <br />a short distance from the face were dr_y. The sandstone and siZtstone roof strata <br />in the Blue Ribbon, Hawk's Nest and Somerset mines also weep for short periods of <br />time following mining and eventually dn7 up. These in-mine observations indicate <br />that the "B-2", "E" and "F" coal seams and their roof strata are not significant <br />regional aquifers. Observation made of mining within the "C" seam at the Bear No. 1 <br />and No. 2 mines and of mining within the "D" seam by Orchard Valley mine indicate that <br />the "C" and "D" seams and their associated roof strata also are not significant <br />regional aqui fers. If the coals and their roof strata were aquifers, these units would <br />have continued to weep throughout the life of these mines. <br />Sorry fractures and faults transect the Mesa Verde Formation and extend vertically to <br />the surface. These faults and fractures produce narrow bands of secondary porosity <br />within the rock strata. These faults and fractures thus become the primary path through <br />which water flaws both vertically between rock strata and horizontally within rock <br />strata. When faults and fractures are encountered within the mines in the North Fork <br />region, they generally produce mine inflows. The flow characteristics of each mine <br />inflow associated with faults and fractures depend upon the Lateral extent and the <br />proximity of the fault or fracture to a stream valley. A1Z inflows from these sources <br />are characterized by an initial surge of water which then either decreases with time, <br />or ceases completely. Since most stream channels in the North Fork drainage basin have <br />developed in zones of weak fractured rock associated with fracturing and faulting, <br />mine inflows from fractures and faults below these streams mimic the temporal flow <br />