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i} <br /> t <br /> I <br /> 1 <br /> ( THE ALLEN MINE <br /> j <br /> } This study was conducted at the Allen Mine, a deep mining operation <br /> J recovering metalurgical-grade bituminous coal . The mine is located 40 <br /> miles west of Trinidad, in Las Animas County, Colorado and has been active <br /> in the removal of coal since 1951 . This coal is interbedded in marine <br /> shale and both are removed during the mining process. The two materials <br /> are separated and the shale waste material , commonly called slack, is <br /> placed in waste dumps near the mine mouth. <br /> i Fifteen years of climatological data has been collected at North <br /> J <br /> Lake, 10 miles north of the mine site. The average annual precipitation <br /> between 1962 and 1976 was 51 cm. During the 3 years of this study preci- <br /> pitation ranged from 34.3 cm in 1978 to 50.8 cm in 1979. <br /> Soil analysis has shown that the waste material contains gravel <br /> 1 fragments greater than 2 mm which account for 38 to 69 percent of the <br /> waste volume. The remaining volume has been classified in texture as a <br /> sandy loam to clay loam. The organic matter content was 1 .0 to 2.8 percent. <br /> This value also reflects carbon contamination from the coal in the waste <br /> r <br /> material . The electrical conductivity ranged from 0.8 to 6.7 mmhos/cm and <br /> the pH was 8.3 to 8.8. The sodium absorption ratio (SAR) ranged from 15 <br /> to 38. The SAR, pH, and electrical conductivity values are all high enough <br /> to potentially inhibit plant growth. <br /> The mine is situated in the valley of the Purgatoire River. The land <br /> adjacent to the mine in the valley bottom is in improved pasture or meadows <br /> used for hay production and livestock grazing. <br /> r <br /> 13 <br />