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of 6.72 SU in the alluvium (CRMW -3B), a median pH value of 5.88 SU in the shallow <br />bedrock (CRMW -3A), and a median pH value of 7.84 in the bedrock (ESPMW -1). <br />Median nitrate values are 2.70, 10.6, and <0.05 mg/L as N for CRMW -3B, CRMW -3A, <br />and ESPMW -1, respectively. Median sulfate values are 734, 742, and 41 mg/L for <br />CRMW -3B, CRMW -3A, and ESPMW -1, respectively. Sulfate concentrations for <br />CRMW -3A and CRMW -3B show an upward trend since approximately 2006. Time <br />series plots for pH, nitrate, and sulfate are provided in Figure 5 -11. <br />Compiled data and statistics for aluminum, manganese, and zinc, which are elevated in <br />the Diatreme, are provided in Tables 5 -15, 5 -16, and 5 -17. The water quality data <br />indicate relatively stable concentrations for aluminum (CRMW -3B and ESPMW -1), <br />manganese (CRM -3A and ESPMW -1), and zinc (CRMW -3A, CRMW -3B, and ESPMW- <br />1). Aluminum concentrations were elevated at CRMW -3A from 1996 until 2003 but <br />have declined to low and stable concentrations. Manganese concentrations at CRMW -3B <br />are elevated, but stable. Other trace metals are analyzed as part of the monitoring <br />program. Median values for arsenic, cadmium, chromium, lead, mercury, selenium, and <br />silver in the ground waters at CRMW -3A, CRMW -3B, and ESPMW -1 were less than the <br />analytical detection limits. Median concentrations of nickel at CRMW -3A and CRMW- <br />3B and copper at ESPMW -1 were above the analytical detection limits, but low. Trace <br />metal data also are provided in Tables 5 -15, 5 -16, and 5 -17. <br />The continued capture of precipitation by the AGVLF in the upper reaches of Arequa <br />Gulch also has impacted the alluvium (CRMW -3B) and the shallow bedrock (CRMW- <br />3A) ground water quality in the middle reaches of the Arequa Gulch drainage. The <br />sulfide oxidation in the exposed spent materials beneath the liner and the transport of the <br />oxidation products likely is causing the gradual increase in sulfate and the spikes of <br />sulfate and other metals in the alluvium (CRMW -3B) and shallow bedrock (CRMW -3A). <br />Concentrations of sulfate and other parameters may continue to spike seasonally and rise <br />overall due to the sulfide oxidation under the AGVLF in the upper reaches of Arequa <br />Gulch. For most other parameters at CRMW -3B and CRMW -3A, water quality <br />conditions in the alluvium and shallow bedrock are expected to be similar to or slight <br />elevated from the current conditions. <br />5.4.4.4 MLE2 Impacts to Ground Waters <br />The implementation of MLE2 will have minimal impact to the ground water resources of <br />Arequa Gulch drainage. <br />'Cripple Creek & Victor Gold Mining Company <br />Cresson Project Hydrologic Evaluation for Mine Life Extension 2 <br />27 <br />