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ALLUVIAL VALLEY FLOOR DETERMINATION <br />CAM - COLORADO PROPOSED COAL LOADOUT NEAR FRUITA <br />MESA COUNTY, COLORADO <br />The alluvial ground water quality is typical of the ground water quality of marine shales <br />in western Colorado. Total dissolved solids concentrations range from 5,800 to 8,800 <br />milligram per liter (mg/L), with an average of 7,300 mg/L for the four monitoring wells <br />(Appendix Q. The water is predominantly a calcium - sodium sulfate water with elevated <br />dissolved iron. For comparison, the Colorado River upstream and downstream of the <br />property had a total dissolved solids concentration of about 600 mg/L in April 2010 and 316 <br />mg/L in June 2010. The upgradient -most well (RW -2) had a selenium concentration of 0.075 <br />mg/L in April 2010, which exceeded the Colorado Basic Ground Water Standard (CBGWS) <br />of 0.05 mg/L. <br />Although the coal would be stored on low permeability clayey material and would overlie <br />15 to 23 feet of silty clay, the nature of a potential leachate from the coal was investigated <br />and compared to existing ground water quality beneath the site. A TCLP leachate analysis <br />was performed on cleaned or washed coal from the McClane Canyon Mine (Appendix D). <br />On an annual basis, potential evaporation exceeds precipitation in this area; therefore, much <br />of the precipitation would be expected to evaporate rather than infiltrate to ground water. <br />However, during particularly wet periods or intense storms, there is the potential for water to <br />run off the coal pile and infiltrate to ground water. The TCLP leachate analytical results <br />indicate that water in contact with the coal would have a very low total dissolved solids <br />concentration (32 mg/L), near neutral pH, and very low dissolved metal concentrations <br />(Appendix D). Compared to the background ground water quality, the coal leachate would <br />be of significantly better quality and, therefore, would not impair existing uses of the ground <br />water. <br />Surface Water Hydrology <br />Reed Wash, a tributary to the Colorado River, is a perennial stream that drains the upland <br />areas north of the project area. The wash flows generally from the northeast to the southwest <br />through the property. Reed Wash flows within an incised channel that is 20 to 25 feet below <br />the general grade. This places the wash in the Colorado River alluvium observed in well logs <br />adjacent to the wash and generally below the water table, and possibly the Mancos Shale. <br />This indicates that the wash is a gaining stream through the property, typical of most western <br />drainages. The geologic logs indicate that the depth to the Mancos Shale is deeper near the <br />