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INTRODUCTION <br />Contour Consulting collected groundwater samples at the GCC Rio Grande Limestone <br />Mine on March 25, 2008 and April 15, 2008. The samples were collected to satisfy <br />quarterly monitoring permit requirements, as stipulated by the Colorado Division of <br />Minerals and Geology (DMG). Initial sampling was conducted on March 25, 2008. <br />Additional sampling of production well DW001 was performed on April 15, 2008, as this <br />well was not plumbed for sampling at the time of the initial event. <br />WORK PERFORMED <br />Contour collected groundwater samples from three shallow alluvial monitoring wells <br />(MW002, MW003, and MW004) in the vicinity of the St. Charles River, and from two <br />production/drinking water wells (DW001 and DW002) associated with plant operations. <br />The alluvial wells represent downgradient conditions with respect to the Cement Plant <br />operations. The production wells are screened in the Dakota Sandstone and provide <br />water quality information for plant operations. DW002 is the northern most of the two <br />productions wells, and DW001 is located south of the plant area. Newly installed well <br />MWOOIA is completed in the Codell Sandstone. This well was sounded and was dry. <br />Samples were not collected from MWOO IA. <br />' Depth-to-groundwater measurements were performed at each alluvial well prior to <br />sampling. Wells were also sounded to determine total depth. The volume of standing <br />water in each well was determined. Each of the alluvial wells were purged using a new <br />disposable poly bailer. A minimum of three casing volumes was purged from each well <br />prior to sampling. <br />All groundwater samples were submitted to Evergreen Analytical Laboratory, located in <br />Wheat Ridge Colorado, for analysis. Evergreen subcontracted analyses for radiochemical <br />parameters to Hazen Research, located in Golden, Colorado. Analyses for asbestos in <br />groundwater were subcontracted to Reservoirs Environmental, located in Denver, <br />Colorado. <br />' RESULTS AND DISCUSSION <br />Results of the groundwater sampling are provided in Table 1. Analytical results provided <br />' by the contract laboratories are presented in Appendix A in PDF format. <br />All samples were submitted for analysis of selected dissolved metals, general chemistry <br />' parameters (including asbestos), and radiochemistry parameters. The results of these <br />analyses are discussed in the following sections.