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West Elk Mine <br />indicate changes in water quality that need to be further investigated. As a result, monitoring of <br />these selected parameters provides a detection system for mining-induced changes in water quality. <br />Therefore, once full-suite analyses have been collected at a site for at least five years, these indicator <br />parameters (pH, conductivity, TDS, and iron) will be collected on an annual basis. <br />Analyses are completed as outlined in the Guidelines for Collection of Baseline Water Quality and <br />Overburden Geochemistry Data (CDMG, 1982). Results aze reported in the Annual Hydrology <br />Reports (AHR). If not already provided in AHR's, baseline data will be provided to CDMG prior to <br />longwall mining under or within the angle-of--draw of a monitored water resource. <br />Groundwater Quantity Characteristics <br />Over 238 exploration holes have been drilled on or near the West Elk Mine coal lease area. Records <br />and consultation with project geologists indicate that water was encountered only sporadically in the <br />Mesaverde Formation, indicating groundwater is localized and of limited azeal extent. As defined in <br />the CDMG rules, an aquifer is "a zone, stratum or group of strata acting as a hydraulic unit that can <br />store or transmit water in sufficient quantities for beneficial use." Based on information presented <br />in the next several sections of this document (i.e., permeability analyses, and water level <br />observations), it is the contention of MCC that none of the geologic members of the Mesaverde <br />Formation are aquifers within the West Elk Mine block. <br />The most immediate assessment of whether a geologic formation can be considered an aquifer is to <br />assess whether water supply wells (a demonstration of beneficial use) have been completed into the <br />~~• formation. As shown in Table 3, there are 29 permitted wells within the West Elk Mine permit <br />boundary. Of these, 17 have reported well yields and 13 have provided well depths (ten wells Iess <br />than 100 feet, three wells between 140 and 191 feet). These values range from a low of 0.0 gpm to <br />a high of 30.0 gpm. The four highest reported yields are from wells drilled to a depth of 10 to 63 <br />feet in Sections 9, 10 and 11 (i.e., in the alluvium of the North Fork). These four wells aze not <br />completed in the bedrock members of the Mesaverde Formation. The other 13 wells with reported <br />yields have a range of 0.0 to 4.0 gpm (seven wells have reported yields of 0.0 gpm) and an average <br />production rate of 0.65 gpm. Closer inspection of the remaining 6 wells with reported well yields <br />above 0.0 gpm shows that all but one is permitted as a monitoring well. As such, only one of the 29 <br />permitted wells appears to have obtained a useable supply (2.0 gpm reported) For beneficial use <br />(stock watering). This well has a depth of 140 feet, within the active groundwater flow zone where <br />there is hydraulic communication with the surface and thus dependence on annual recharge events. <br />Given the lack of beneficial use of these formations as a water supply, it is concluded that these <br />formations are not aquifers. Further evidence to support this conclusion is provided by the low <br />permeability data described later in this section. <br />Wells have been completed in a variety of formations for varying purposes. Formations in which <br />groundwater monitoring data have been collected include the Rollins Sandstone, various members <br />of the Mesaverde Formation, and colluvial and alluvial deposits. <br />In addition to water level data collection, hydrogeologic chazacteristics (i.e. transmissivity, <br />hydraulic conductivity, and yield) of many of these formations have been obtained from pumping <br />2.04 -61 RevisedNavember 2004 PRIO <br />