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0 0 Pacific EcoRisk Environmental Consulting & Testing treatment consisting of Control treatment medium similarly adjusted to pH 8.5 was also prepared and tested. 2.3 Acute Toxicity Testing with Fathead Minnows The fathead minnows used in these tests were obtained from a commercial supplier ('T'homas Fish Company, Anderson, CA). These fish were maintained at 20°C in aerated aquaria containing EPA synthetic soft water prior to their use in these tests. These hazardous waste evaluations were run at sample concentrations of 250, 500, and 750 mg/1., with a Lab Water Control consisting of the same synthetic EPA "soft" water. There were two replicates at each test treatment, each replicate consisting of 9.2 L of media in a 10-L container. Water quality characteristics (pH and dissolved oxygen ID.O.1) were determined for the test solution in each test replicate prior to initiation of this test. The tests were initiated with the random allocation of 10juvenile fathead minnows into each replicate container. These containers were placed in a temperature -controlled room at 20°C, under fluorescent lighting on a 161-:81D photoperiod. Each day, each replicate container was examined, and the number of live fish in each was recorded. Routine water quality characteristics (temperature, pH, and D.O.) of the treatment waters were measured and recorded for each replicate container each day. After 96 (t2) hrs, the tests were terminated and the number of live fish in each replicate container was determined. The fish in randomly selected Lab Control treatment replicates were then euthanized and measured for total length (to the nearest.0.1 mm) and weighed (to the nearest 0.001 g). The resulting survival data for each waste sample were evaluated to determine the LC50 using the CETIS" statistical software (TidePool Scientific, McKinleyville, CA). Page 2 t U> 6/28