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Description of the Environment <br />General Area <br />The Lorencito Canyon mine is situated near the center of the Raton Basin, southeast of the town <br />of Weston, Colorado. The County Map Topographic Series, Las Animas County, Colorado, <br />sheet 4 of 7, published by the United States Geological Survey, depicts the greater mine area. <br />Lands in this area are a small part of the larger Park Plateau, a portion of the Great Plains <br />physiographic province, consisting of dissected highlands that separate the High Plains to the <br />east from the Rocky Mountains to the west. <br />The major structural feature in the region of the mine area is the Raton Basin, a broad, <br />asymmetric synclinal basin with its axis trending north - south. Rock units deposited during the <br />Cretaceous period of the Mesozoic Era and during the Paleocene period of the Cenozoic Era are <br />exposed throughout the basin due to uplift and subsequent erosion. Coal seams in the Vermejo <br />Formation and the Raton Formation are exposed at various locations throughout the basin. Coal <br />mining has been conducted in the area since the 1850's, mostly in underground mines faced -up <br />into coal seam outcrops in the valleys. Coal quality is generally very good, with low sulfur <br />content and good coking qualities in many of the seams. Due to parting and splits in the seams, <br />much of the coal mined in the region requires washing prior to loadout and shipment. <br />The Purgatoire River flows through the area and is the major stream that drains the region. Its <br />headwaters are in the Sangre de Cristo mountain range to the west and the Spanish Peaks to the <br />northwest. The North Fork of the Purgatoire drains the Spanish Peaks area, the Middle Fork <br />drains the area west of Stonewall, Colorado, and the South Fork of the Purgatoire drains the <br />areas south of Colorado Highway 12 into New Mexico to the south. The Purgatoire River drains <br />404 square miles above its confluence with Lorencito Canyon. The United States Geological <br />Survey (USGS) has operated two stream gauging stations in the vicinity; site 07124050 at <br />Stonewall, Colorado and site 07124200 at Madrid, Colorado. The Stonewall site drains 57 <br />square miles and the Madrid site, above Trinidad Reservoir, drains 505 square miles. Numerous <br />perennial, intermittent, and ephemeral streams drain to the Purgatoire between these two sites. <br />Surface water is characterized as a calcium/sodium bicarbonate water, neutral to slightly <br />alkaline, with low hardness. pH ranges from 6.15 to 8.8 and Total Dissolved Solids (TDS) <br />ranges from 50 -650 mg /l. <br />Ground water occurrence in the region can best be described as limited. Consolidated bedrock <br />aquifers generally have a low hydraulic conductivity and a low storativity, rendering bedrock <br />aquifers unusable for sources of economic water. Alluvial groundwater is present in the major <br />alluvial valleys of the region and is used for domestic purposes associated with ranching <br />activities. <br />Ground water quality is variable, but can generally be described as fair quality. Alluvial water is <br />suitable for most uses where TDS levels are not elevated. Bedrock water quality is fair from <br />shallow aquifers, but degrades with depth and would not generally be suitable for domestic use. <br />