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Secondary standards for manganese are exceeded in alluvial wells MWO02 and MW004. <br />Secondary standards are typically associated with aesthetic impacts to water quality, <br />including taste, staining potential, and potential for fouling. <br />General Chemistry <br />Results of the general chemistry results are presented in Table 1. Anion and cation <br />balances were poor for wells MWO02 and MWO03, with percent differences greater than 10 <br />percent. The laboratory attributed the poor balance precision to impacts of elevated <br />bicarbonate that was calculated from the total, rather than the dissolved fraction of the ion <br />analyses. No action is taken with respect to data quality due to the poor ion balance in the <br />groundwater samples. <br />General chemistry parameters do not have primary health based standards. Fluoride, <br />chloride, and sulfate have secondary or agricultural standards. The sulfate concentrations <br />in all of the alluvial wells sampled have exceeded the secondary domestic drinking water <br />standard of 250 mg/L in each of the sampling events. Excess sulfate in drinking water may <br />have negative aesthetic impacts such as laxative effects. <br />Well MWO04 has historically recorded the highest sulfate, TDS, and nitrate concentrations, <br />though well MWO03 has slightly higher sulfate and TDS concentrations in the previous <br />event. MWO04 is located in the most extensive flood plain setting of the three alluvial <br />wells, and may be subject to more saturated geochemical conditions, relative to the other <br />two alluvial wells. <br />Radiochemistry <br />Results of the radiochemistry analyses show that gross alpha activities exceed the Colorado <br />groundwater standard of 15 picoCuries/Liter (pCi/L) in wells MWO02, MWO03, MWO04, <br />' and Dup-O1(MWO02 duplicate sample). The 15 pCi/L standard excludes activities due to <br />radon and uranium. Radon and uranium activities were not measured, and the gross alpha <br />contribution from these two sources cannot be evaluated at this time. Gross alpha activities <br />' have exceeded the standard in well MW004 in all previous sampling events. Gross alpha <br />activities exceeded the standard at well MWO03 in the previous two 2008 sampling events, <br />and exceeded at MWO02 in the previous 3 events. <br />The combined radium 226 and 228 activity exceeded the 5 pCi/L Colorado groundwater <br />' <br />standard in wells MW003. Radium activity has exceeded the standard in well MWO04 for <br />' several of the previous monitoring events. <br />There is no indication that any plant activities are responsible for elevated radiochemistry <br />' activities at the GCC Facility. Elevated radionuclide activities in Colorado aquifers are <br />3