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Mountain Coal Company CO-0038776 SeaCrest Number: 303130 <br />conductivity, dissolved oxygen, chlorine, ammonia and pH. Alkalinity and hardness were <br />determined titrimetrically according to methods described in Hach Chemical Co. (1997). <br />Ammonia was measured by a Thermo Orion ion-specific electrode according to procedures in <br />APHA/AWWANVEF (1998). <br />A total of twenty organisms at each concentration were used for the daphnia test. <br />Daphnia magna were exposed in 30 ml plastic disposable beakers. Approximately twenty ml <br />of the effluent mixture was added to each beaker. Fathead minnows were exposed in 260 ml <br />plastic cups containing 200 ml of medium. Forty minnows were used at each concentration, <br />following State of Colorado WET testing guidelines. Exposure medium was replaced after each <br />24 hour period and organisms surviving at each concentration were counted and recorded. <br />Routine measurements were made of temperature, pH, and dissolved oxygen in each <br />concentration. <br />The acute tests were started on April 2, 2003 and were performed according to the <br />procedures outlined in Weber (1993). The Daphnia magna test was conducted over 48 hours, <br />the fathead minnow test for 96 hours. The tests were run with exposure concentrations of <br />100%, 50%, 25%, 12.5%, and 1.90% effluent. Water used for the control and as the dilution <br />water was moderately-hard laboratory reconstituted freshwater. <br />Data Analysis <br />Data from the tests were analyzed on a Pentium personal computer. Where applicable, <br />LC50's were calculated using EPA's TOXDATMnlti-Method Program according to the binomial, <br />probit, or moving average methods. Statistically significant differences between control and <br />exposed organisms were determined using the TOXSTAT software developed at the University <br />of Wyoming. <br />RESULTS <br />The results of the tests are summarized in Appendix 2. There was some mortality in the <br />Daphnia magna test where survival was 60% in the 100% effluent and ranged from 75-100% <br />in the remaining effluent concentrations. Survival was 100% in the control. No LC50 <br />concentration was produced in this test. <br />The fathead minnow test also showed some toxicity. Survival was 75% in the 100% <br />effluent and ranged from 68-100% in the remaining effluent concentrations. Control survival <br />was 100%. <br />The SeaCrest Group <br />