2008-04-15_REVISION - M1980244 (325)

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Main project area hydrologic conditions 11 townsite drainage areas, and historical mine sites with associated waste rock piles and mine drainage features. The limits of the Cresson Project components are shown on Fi ure 1.2. Th r ' 9 e e ~s no Cresson Project surface mine disturbance in the main reach of the Cripple Creek drainage (as outlined in Figure 3.1), and no disturbance in the main reach of the Cripple Creek drainage is proposed in the MLE application. Cresson Project disturbances in the Poverty Gulch, Gold Run, Squaw Gulch, and Arequa Gulch drainages are described in their respective sections below. Surface Water Surface water conditions in the Cripple Creek drainage are assessed at four locations; CC-01, CC-02, CC-03, and CC-04. Surface water station locations are shown on Figure 3.1. Water quality statistics (number of measurements, less than detection events, maximum value, minimum value, average value, and standard deviation), and field parameter data (number of measurements, less than detection events, maximum value, minimum value, average value, and standard deviation) have been compiled for each location. The period of record, stream flow and water quality summaries for the sample stations CC-01, CC-02, CC-03, and CC-04 are provided in Tables Al through A4 (Attachment A), respectively. Surface water flows in the Cripple Creek drainage are seasonally influenced at the four stations. Low flows occur during August through March and range from less than 10 to 164 gallons per minute (gpm) at the four stations. High flows occur during April through September and range from 1,560 to 2,264 gpm for the four stations. Minimum flows in the upper reach of Cripple Creek (station CC-01) are, in part, due to the discharges from the City of Cripple Creek Publicly Owned Treatment Works (POTW). Flows peak in the spring due to snowmelt runoff and/or in the summer due to seasonal rains and runoff. Surface waters in the upper reach of Cripple Creek (CC-01, CC-02, and CC-03) are characterized as mixed sodium-calcium and sulfate-bicarbonate-chloride waters. Surface water in the lower reach of Cripple Creek (CC-04) is characterized as calcium sulfate water. A piper plot (Figure 3.2) shows the major ion water chemistry for the Cripple Creek surface water stations. Data in Tables Al through A4 (Attachment A) indicate average pH values that are slightly above neutral and stable through the downstream stations from CC-01 (7.8 standard units [su]), to CC-02 (8.0 su), to CC-03 (7.9 su), to CC-04 (8.0 su). Average nitrate values decrease downstream from CC-01 (11.25 mg/L), to CC-02 (11.76 mg/L), to CC-03 (10.82 mg/L), to CC-04 (7.28 mg/L). The elevated nitrate values at CC-01 and downstream may be due to the City of Cripple Creek POTW discharges located above CC-01. Average sulfate values increase in the downstream direction from 126 mg/L at CC-01, to 113 mg/L at CC-02, to 139 mg/L at CC-03, and to 190 mg/L at CC-04. Groundwater There are no groundwater monitoring wells in the Cripple Creek drainage. There are monitoring wells located in the tributaries to Cripple Creek (Squaw Gulch, Gold Run, Poverty Gulch, and Arequa Gulch). The data from these monitoring wells are addressed in the sections for those drainages below. 2736 Cripple Creek & Victor Gold Mining Company Water Management Consultants