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The Kirtland Shale conformably overlies the Fruitland Formation. This shale is divided into three main <br />members: the upper and lower shales and the middle Farmington Sandstone. The Farmington Sandstone <br />member forms a permanent ridge separating Carbon Junction Canyon and REA Canyon. The lower shale <br />member consists of gray to gray-green shale and sandy shales. The upper shale member consists of <br />interbedded shales and sandstones. <br />The Quaternary terrace deposits consist of Pleistocene-aged gravels related to glaciation in the area. <br />Three gravel terrace layers have been mapped in the area and represent previous flood plains of the <br />Animas River. These deposits vary between i and 100 feet thick and consist of boulders and cobbles in a <br />silt clay matrix. <br />Quaternary alluvial deposits are primarily located along the Animas River. Thin (less than three feet <br />thick) isolated alluvial bodies are located in Carbon Junction Canyon. <br />The Quaternary terrace deposits are at best limited aquifers. These deposits have a coarse gravel-boulder <br />layer at their base that tends to drain the deposits to the side slopes of the Animas River Valley. The <br />terrace deposits do not supply subirrigation to crops. These terrace deposits are currently used regionally <br />for dry land wheat farming. <br />The alluvium of the Animas River is a regional aquifer located 400 feet below the main mining operation. <br />The alluvium is poorly sorted and coarse-grained, with ground water levels coincident with the river <br />level. The alluvial body thins and becomes narrow at the point where the Animas River cuts through the <br />Pictured Cliffs Sandstone and Fruitland Formation. <br />Ground Water Hydrology <br />Two aquifers are in hydrologic communication with the Carbon Junction Mine: the Animas River <br />alluvium (400 ft. downslope from the mine permit area) and the Pictured Cliffs sandstone (subcrops <br />beneath the mine pit area). <br />Monitoring of alluvial ground water has not been required at the Carbon Junction Mine. Animas River <br />alluvial water can be expected to have not been degraded by coal mining at Carbon Junction because the <br />less than 10-acre surface area of coal spoil at the mine would not generate enough leachate to overcome <br />the dilutional effect of native alluvial ground water. <br />Bedrock ground water at the mine was monitored in well 95-1 from 1995 through 2005. This well <br />presumably was completed in the Fruitland Formation and Pictured Cliffs sandstone. Well 95-1 is <br />located within the expected flowpath of any coal spoil leachate that would be generated in the Carbon <br />Junction backfilled pits. Monitoring data from this well did not show evidence of leachate prior to 2006. <br />The requirement to monitor well 95-1 was eliminated in TR-13. Elimination of this monitoring was <br />based chiefly on: a) historical monitoring data from the wells indicating no impacts from coal mining at <br />Carbon Junction, b) recognition that any coal spoil leachate generated by and migrating from the <br />relatively small (less than 10-acre) pit area at Carbon Junction would undergo significant attenuation and <br />dispersion in the Animas River alluvium and Pictured Cliffs sandstone within a few hundred feet of the <br />mine pits. <br />The relatively small pit area of the Carbon Junction Mine (less than 10 acres) indicates the mine does not <br />have the potential to negatively impact ground water quality; therefore, a ground water point of <br />compliance has not been established. <br />5