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value, standard deviation, and median value) for the sample stations GV -01, GV -02, and
<br />GV -03 are provided in Tables 6 -1, 6 -2, and 6 -3, respectively. Time series plots of
<br />selected parameters (flow and pH, nitrate, and sulfate) are provided in Figures 6 -1 and 6-
<br />2, respectively.
<br />6.3.3 Discussion
<br />Surface water flows in the Grassy Valley are seasonal and generally low. Flow, when it
<br />occurs, is typically in the 2 quarter due to snowmelt and runoff. Occasional 3` and 4th
<br />quarter flows due to seasonal rains also are observed. Median hand- measured (non -zero)
<br />flows are 15, 20, and 25 gpm for GV -01, GV -02, and GV -03, respectively. Flow data are
<br />shown in Figure 6 -1. Flow rates (when reported for the same day) increase into a
<br />downstream direction from GV -01 to GV -02, but often decrease from GV -02 to GV -03.
<br />A more detailed analysis of the Grassy Valley surface water flows is presented in
<br />"Cresson Project Hydrogeochemical Evaluation" dated February 2012 and prepared by
<br />ABC.
<br />The surface waters in the Grassy Valley (GV -01 to GV -02 to GV -03) are characterized as
<br />sodium - bicarbonate to calcium- sulfate waters. Water quality data provided in Tables 6 -1,
<br />6 -2, and 6 -3 show median field pH values that are circum- neutral and stable at 7.29 SU at
<br />GV -01, 6.65 SU at GV -02, and 6.80 SU at GV -03. Median nitrate values decrease from
<br />GV -01 (0.55 mg/L as N) to less than detection values ( <0.05 mg/L as N) at GV -02 and
<br />GV -03. Median sulfate values increase in the downstream direction from 41.6 mg/L at
<br />GV -01, to 322 mg/L at GV -02, and then decrease to 289 mg/L at GV -03. The
<br />downgradient increase in sulfate between GV -01 and GV -02 potentially is attributable to
<br />the historic mine features (e.g., Cameron workings) in Grassy Valley at and above GV-
<br />02.
<br />Compiled data and statistics for aluminum, manganese, and zinc, which are common
<br />geochemical indicators in the Diatreme, are provided in Tables 6 -1, 6 -2, and 6 -3. The
<br />water quality data indicate that aluminum and zinc concentrations have been low and
<br />stable for the individual stations GV -01, GV -02, and GV -03 since 1997, 1996, and 1996,
<br />respectively. Manganese concentrations have been low and stable for GV -01, but
<br />elevated and variable for GV -02 and GV -03 since 1997, 1996, and 1996, respectively.
<br />Other trace metals are analyzed as part of the monitoring program. Median values for
<br />arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, and silver in the
<br />ground waters at GV -01, GV -02, and GV -03 were less than or very close to the analytical
<br />detection limits. Trace metal data also are provided in Tables 6 -1, 6 -2, and 6 -3.
<br />'Cripple Creek & Victor Gold Mining Company
<br />Cresson Project Hydrologic Evaluation for Mine Life Extension 2
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