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All groundwater samples were submitted to Accutest Laboratory (formerly Evergreen <br />Analytical Laboratory), located in Wheat Ridge Colorado, for analysis. Accutest <br />subcontracted analyses for radiochemical parameters to Hazen Research laboratory, located <br />in Golden, 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. <br />All samples were submitted for analysis of selected dissolved metals, general chemistry <br />parameters, and radiochemistry parameters. The results of these analyses are discussed in <br />the following sections. <br />Dissolved Metals <br />The following dissolved metals were not detected in any samples collected: Beryllium, <br />chromium, cobalt, nickel, silver, vanadium, zinc, antimony, arsenic, cadmium, copper, lead, <br />thallium, and mercury. Aluminum was detected in well MW-003 at a concentration near <br />the reporting limit in this event, though aluminum has not been previously detected. This <br />suite of metals has typically been reported as non-detect in all previous monitoring events. <br />All dissolved metals detections are shown in bold text in Table 1. <br />Dissolved metals results for the first half, 2010 sampling at GCC are compared to values <br />presented in Tables 1, 2, and 3 of the Colorado Basic Standards for Groundwater. <br />) <br />(htti)://www.cdphe.state.co.us/regulations/wqccregs/index.html <br />The applicable values for the basic standards for dissolved metals are included in Table 1 <br />for reference. If there is no health-based standard for a metal, the secondary or agricultural <br />standard is listed. Any exceedances to the basic standards are shown as shaded cells in <br />Table 1. The only dissolved metal detection to exceed a primary drinking water standard is <br />that for selenium in alluvial well sample MW004. This selenium detection corroborates <br />similar results from the previous 2008 and 2009 events. Elevated selenium concentrations <br />associated with certain shallow sedimentary rock units in the Pueblo area have been well <br />documented, and include the St. Charles River alluvium (p d 2007, GEI Consultants. Inc. <br />Aquatic Biological Monitoring; and Selenium Investigation of the Arkansas River. Fountain <br />Creek Wildhorse Creep and the. St. Charles River). <br />2