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<br />4.6.1.3.5 Ground Water <br />Affected Aouifers <br />Test drilling identified four water-bearing zones: the P.ollins <br />sandstone, the Upper sandstone, and the Upper and Lower zones within <br />the Paonia Member. It is presumed that the Middle sandstone is also <br />water-bearing, but it was not tested because it is stratigraphically <br />separated from mining activities by several hundred feet of relatively <br />impermeable sediments. Snowmass Coal Company plans no mining below <br />the Upper sandstone in the vicinity of Mine No. 3; therefore, the <br />Middle sandstone will not be affected. <br />Estimate of Transmissivity <br />• Field data indicate that each of the affected aquifers has low per- <br />meability. Mine inflow averaged 153,000 gallons per day (gpd) over <br />the last year of operations. Mine Number 3 contributed an average of <br />45,000 gpd while Mine Number 1 produced an average of 108,000 gpd. <br />A calculation of the transmissivity of the strata overlying the mine <br />in the vicinity of North Thompson Creek can be made using the <br />following form of Darcy's Law: <br />T = Q = 153,000 gal/day <br />WI (52.8 ft)(1) <br />= 2,898 gpd/ft <br />• <br />4-118 <br />