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Secondary standards for manganese are exceeded in alluvial wells MW002, MW003, and <br />MW004. Secondary standards are typically associated with aesthetic impacts to water <br />quality, 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 are generally acceptable. All differences between cations and anions are less than <br />ten percent, with the exception of sample DUP001 at 11 percent (field duplicate of well <br />MW002). No action is taken with respect to data quality due to the slightly poor ion <br />balance in the duplicate sample. <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 current <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 MW002, MW003, MW004, <br />and Dup-01 (MW002 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 MWO04 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 />standard in wells MWO02 and MW004. Radium activity has exceeded the standard in well <br />MWO04 for four of the past five 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 />generally associated with leaching from granitic bedrock masses that underlay many <br />3