Laserfiche WebLink
Test Procedures <br />Upon receipt at the lab, the water samples were analyzed for alkalinity, hardness, <br />conductivity, dissolved oxygen, chlorine, ammonia and pH. Alkalinity and hardness were <br />determined titrimetrically according to methods described in Hach Chemical Co. (2002). <br />Ammonia was measured by a Thermo Orion ion-specific electrode according to procedures in <br />APHA/AWWAM/EF (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 of <br />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 8, 2004 and were performed according to the <br />procedures outlined in EPA-821-R-02-012 (2002). The Daphnia magna test was conducted <br />over 48 hours, the fathead minnow test for 96 hours. The tests were run with exposure <br />concentrations of 100%, 50%, 25%, 12.5%, and 1.9% effluent. Moderately hard laboratory <br />reconstituted freshwater was used for the control and for the dilutions. <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 TOXDATMultl-Method Program according to fhe 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. An LC50 of 44.48%was created <br />in the Daphnia magna test. Survival was 15% in the 100% effluent and ranged from 75-100% in <br />the remaining effluent concentrations. Survival was 100% in the control. <br />The fathead minnow test showed 100% survival in all effluent concentrations. Control <br />survival was also 100%. No LC50 was created with the fathead minnows. <br />The SeaCrest Group 3 <br />