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NIa[thew S. Hayes <br />June 28,1989 <br />Page 5 <br />'Table 5 includes analyses for samples from 19 wells completed in <br />the Mesaverde Formation. The range of specific conductances was <br />from 325 to 5,390 µmhos/cm with an average of 1,434 ~cmhos/cm. <br />The range of dissolved solids was 206 to 3,360 mg/1 with an <br />average of 880 mg/1. The dominant cation was sodium and the <br />dominant anions were bicarbonate and sulfate. Concentrations of <br />dissolved solids, sulfate, iron and manganese exceeded the U.S. <br />Environmental Protection Agency's (U.S. EPA) standards for <br />secondary maximum contaminant levels of public drinking waters. <br />Concentrations of fluoride and selenium exceeded the U.S. EPA <br />primary drinking water standazds in some samples." <br />Information available to WECC indicates that the Rollins Sandstone <br />although considered a regional aquifer in some publications, does not <br />contain water of useable quality or quantity in the permit area. Since no <br />impacts from the extensive workings of other mines in the azea is evident, <br />we submit that monitoring should be concentrated on mine water <br />discharges and wells associated with B seam mining for the following <br />reasons: <br />a. Disturbances and changes to water quality, if they occur, will be <br />manifested in B seam discharge water and B seam monitoring wells <br />prior to any potential impacts to the Rollins. The B seam is <br />separated from the Rollins by siitstones, shales and another coal <br />seam. <br />b. It is unlikely the Rollins would be used as a primary drinking water <br />source because of its great depth outside stream valleys and the <br />ready availability of better quality surface water near the stream <br />valleys. <br />c. Impacts from historical mining activities in the area, if any, could <br />not be distinguished from natural background conditions. <br />