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CONCLUSIONS <br />Results of the first half, 2009, groundwater sampling performed at the GCC Rio Grande <br />Cement Plant during May 2009 are presented herein. All analyses required were <br />performed as requested. <br />Results for several dissolved metals were found to be non-detect for all wells. These <br />metals were also reported as non-detect in the previous quarterly sampling events. If <br />these constituents continue to be non-detected in future samplings events, or if these have <br />not been historically detected, GCC Rio Grande may petition to have these constituents <br />removed from the routine monitoring program. / <br />' Selenium was the only metal to exceed aprimary drinking water standard <br />Ths occurred <br />at well MW004. Selenium has exceeded the drinking water standard at well MW004 for <br />' eac of the monitoring events performed at the site to date. Elevated selenium in the <br />vicinity of the St. Charles River and other areas is documented to be naturally occurring <br />' with sources in unit of the Pierre Shale, the Niobrara Formation and from soils formed <br />from those bedrock units. Secondary water quality standards were exceeded for <br />dissolved manganese and for sulfate. These constituents may have negative aesthetic <br />impacts on water used for domestic purposes. <br />Elevated radiochemical activities are likely associated with naturally occurring conditions <br />in the St. Charles River alluvium. There is no indication that the elevated radiochemical <br />activities have any association with cement plant activities. <br />5