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Tracer Inoculation of the Sunnyside Mine <br /> Page 2 <br /> SGC - The identification of a suitable tracer and method of <br /> distribution was developed by an independent technical <br /> consultant and reviewed for deficiencies by a second <br /> independent technical consultant before submittal to DMG. <br /> The targeted tracer concentration (1 mg/1 ) for the mine <br /> pool was kept below the literature value of chronic <br /> toxicity (1 . 6 mg/1 ) for sensitive species (Ceriodaphnia) <br /> and yet high enough to detect at the surface with a 100: 1 <br /> dilution. It is recognized that lateral distribution <br /> within the mine can be achieved fairly well but vertical <br /> distribution can only be achieved by mine level (vertical <br /> blocks ranging in height) with dependence on rising water <br /> to dilute the concentration to the targeted average <br /> concentration. Spillage and/or washing (before the <br /> valves are closed) could also cause portal discharges <br /> higher in concentration than the literature value <br /> although , it is not anticipated that literature acute <br /> values (2000-3000 mg/1 ) could ever be approached. <br /> SGC concludes as a result of its technical analysis that <br /> tracer inoculation and monitoring coupled with water pool <br /> level monitoring will provide a reliable tool for <br /> evaluating whether water from the Sunnyside Mine water <br /> pool is escaping to surface at a rate or quantity <br /> significantly different than anticipated. The regulatory <br /> status of any such waters is not addressed in this <br /> letter . <br /> In order to address CDPHE concerns, SGC has or will do the <br /> following : <br /> 1) Hydro-Search, Inc . (formerly Simon Hydro-Search) was <br /> commissioned to review their previous report and research <br /> available literature to determine if any site specific <br /> conditions exist that would cause bromide to fail as a tracer . <br /> The report is attached for your review. It reaffirms the <br /> conclusion that bromide will work as a tracer to detect water <br /> migrating from the Sunnyside Mine to surface. <br /> 2) The third quarter WET test for the American Tunnel discharge <br /> is scheduled for the week of September 19, 1994. SGC has also <br /> scheduled chronic WET tests with sodium bromide addition at <br /> concentrations of . 1, 1, 10, 100 and 1000 mg/l Br to be run <br /> concurrently in order to confirm literature values or see if <br /> the chemistry of Sunnyside Mine waters changes these values. <br /> The results will be submitted upon completion of the tests. <br />