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• DISCUSSION <br />Somerset Mine effluent has repeatedly failed the C. dubia Whole <br />Effluent Toxicity (WET) test portion of the facility's permit to <br />discharge. Each wET test has recorded high al}salinity. Therefore, <br />a test was performed to observe if a decrease in mortality would <br />occur with a decrease in alkalinity. Results found that survival <br />was increased when alkalinity was decreased with H2SOq. <br />None of the tests performed in this most current toxicity <br />identification evaluation removed or significantly decreased <br />Somerset Mine effluent toxicity. Alkalinity was significantly <br />decreased with the addition of HCL in the pH 3 adjustment test but <br />no significant change in mortality was observed (as compared to <br />baseline and initial LCSO's). Mortality was increased by 20~ with <br />the addition of NaOH to the effluent in the pH 11 adjustment test. <br />Mortality was not decreased with the addition of EDTA. Time to <br />mortality in the EDTA test showed EDTA toxicity at upper EDTA <br />concentrations and effluent toxicity at lower EDTA concentrations. <br />The oxidant reduction test was non conclusive in that sodium <br />thiosulfate toxicity was not exhibited and therefore oxidants could <br />not be entirely excluded as the toxicant. However, the initial <br />effluent chlorine concentration was found to be <0.10 mg/L which <br />would exclude chlorine. <br />Mortality was not decreased at any EDTA <br />indicates that no EDTA chelatible metals <br />effluent at toxic levels. Also, the results <br />not implicate a specific heavy metal as <br />toxicant. However, the scan did measure <br />concentration at 1005 mg/L. <br />-5- <br />concentration which <br />were present in the <br />of the ICP metals did <br />a possible effluent <br />the effluent Sodium <br />COMMER CIALTESTING & EN GIN EE RING CO. <br />.~inal Waiermarheo Pnr Your Pmiecoen ~~~ <br />