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has shown a mean field pH value of 6.0 over the period 1987-1991. This drainage passes over <br /> mineralized bedrock, but does not pass through any mine workings prior to sampling. Water <br /> from this drainage shows elevated concentrations of heavy metals including the following <br /> average values over the period 1987-1991: 0.0037 mg/1 of cadmium, 0.033 mg/1 of copper, <br /> 0.17 mg/I of lead, and 1.9 mg/1 of zinc (Appendix Q. The preceding averages assume the <br /> detection limit value was present when an element could not be detected. The range of values <br /> is large and depends on the quantity of flow, etc. The maximum measured concentrations for <br /> the same elements are as follo s: 0.012 mg/I of cadmium, 0.17 mg/1 of copper, 0.882 mg/1 of <br /> lead, and 5.9 mg/I of zinc. Tl ese surface drainages are now largely routed through the mine <br /> workings and out the Terry Tunnel. <br /> Many iron bogs are present in both the North and South Forks of Cement Creek, indicating <br /> metal-laden water is, or has been, discharging to Cement Creek. As discussed in section 3.1.5, <br /> prior to mining the springs discharging to the Cement Creek drainage above Gladstone probably <br /> had a pH of less than 5 and had elevated levels of metals. Therefore, the pH of the base flow <br /> of Cement Creek would also have been less than 5.0. The pH and metals content of Cement <br /> Creek would have varied depending on snowmelt and precipitation conditions. <br /> As in Sunnyside Basin, many surface drainages which are tributary to Cement Creek pass over <br /> mineralized bedrock and react with sulfides. A pH of 4.4 was measured on August 2, 1991 in <br /> one such tributary to the South Fork of Cement Creek. No mine development, historical or <br /> active, exists upstream of wherle this measurement was taken. <br /> sanjuan\sunn)\110361\mt9I.Rpt 30 <br /> e�� simon '.'-ff©Ho=REfiMH <br />