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Lake Emma was a glacial tarn in Sunnyside Basin at an elevation of approximately <br />12,250 feet msl. On June 4, 1978 Lake Emma drained into workings on the Spur <br />vein causing massive damage throughout the mine (Bird, 1986, p. 135). In areas of <br />high permeability a lake can usually be considered to represent the water table. <br />However, this does not appear to have been the case for Lake Emma. Two samples <br />of the lacustrine clays which formerly were under Lake Emma were tested in August <br />1988 and shown to have permeabilities ranging from 1.6 x 10-' to 6.7 x 10'9 cm/sec <br />under 95% relative compaction. These permeability values are very low and little <br />water would have been transmitted through such material. Lake Emma is considered <br />to have been perched on low permeability lacustrine clays. <br />3.4 Pre-Mining Direction of Ground-Water F/ow <br />Prior to the existence of the mine, the gradient was approximately 0.1 feetffoot from <br />the head of Sunnyside Basin to either Cement Creek, at Gladstone, or to the Animas <br />River at the site of Eureka (see Table 1). If the pre-mine hydraulic head under <br />Sunnyside Basin had been higher or lower the hydraulic gradient would have a <br />different value, but the rate of change in gradient would be about the same to the <br />southeast (toward Midway Mill site) as to the southwest (toward Gladstone). <br />Gunny\wpltraci122511Mar1993.fipt 19 <br />Hsi S1tT1011 HYDRO-SEARCH <br />