2010-07-02_ENFORCEMENT - M1977300 (2)

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approximately 35 mg/L. See Whetstone Report at p. 9-43. That is more than 1000 times the state water quality standard of 0.03 mg/L. As set forth below, Cotter agrees there is a hydraulic connection between the mine pool and Ralston Creek. Ralston Creek flows into Ralston Reservoir, one of the primary water sources for residents of Denver and Arvada. The mine itself is located .06 miles from Ralston Creek and 1.92 miles from Ralston Reservoir. Whetstone Report at p. 8-1. Given the contaminants in the mine pool, the pool's hydraulic connection to Ralston Creek and that the creek flows into a drinking water source, there must be certainty in the corrective actions imposed to address the violations. Dewatering the mine pool provides that certainty. In its EPP and its Technical Memo, Cotter acknowledges that the mine pool has a hydraulic connection to the alluvium. Technical Memo at p. 2 and footnote 1 and Whetstone Report at pp. 7-3, 8-37, 8-41, 9-4, 9-5,15-2 and 15-10. Cotter theorizes based on a conceptual model that has not yet been tested by monitoring, that the hydraulic connection between the mine pool and the creek is weak and any flow from the mine pool is low. Id. Cotter states, however, that the mine pool may contribute up to 8% of the chemical load discharging into the alluvial ground water. Id. Moreover, Cotter cannot state with certainty whether the mine pool is connected to Ralston Creek by any other pathway than the alluvial ground water. Thus, Cotter's plan to treat alluvial water would not be sufficient since it would not capture mine water discharges at other locations. For example, as Cotter acknowledges, there are 33 boreholes that Cotter drilled into the valley floor that Cotter cannot locate and does not know whether such boreholes were properly plugged. Whetstone Report at p. 9-5. Cotter theorizes that "Flow from boreholes and fractures is believed to be low based on mixing calculations...." Id. In addition, the Schwartz trend intersects Ralston Creek about 1,900 feet from the mine and is characterized by brittle fracturing and is the primary host for uranium. Whetstone Report at p. 8-32. This trend has a measurable effect on electrical conductivity in Ralston Creek. Id. However, Cotter states that because no electrical conductivity survey exists prior to mining or during mining operations, Cotter does not know whether water in the flooded underground mine is influencing water quality in Ralston Creek at the Schwartz Trend intersection or whether the Schwartz trend always discharged water with higher TDS than the creek in this location. Whetstone Report at pp., 8-32, 33 and 41. ` Cotter's EPP lists a number of constituents that are far above Colorado groundwater standards: Total Dissolved Solids are near 3,300ms* [; molybdenum is 1.45 mg/L. and total radium 2-16 is 175 pCiA., Whetstone Report at p. 9-34. 10