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Mountain Coal Company CO - 0038766 SCG Project No.: 304225 <br />Site: West Elk Mine <br />concentrations included 0%(control), 1.9%, 12.5%, 25%, 50% and 100% effluent mixtures. <br />Moderately hard laboratory reconstituted water was used as the dilution water and control for the <br />tests. Reconstituted water is prepazed by adding sodium bicazbonate, calcium sulfate, <br />magnesium sulfate and potassium chloride to deionized water. <br />A total of 20 organisms at each concentration were used for the Daphnia magna tests. <br />Daphnia magna were exposed in 30m1 plastic disposable beakers, each of which contained 15m1 <br />of the effluent mixture. Fathead minnow tests were performed in 260m1 plastic cups containing <br />200m1 of test medium. Ten fish were used in each of the four replicates for a total of 40 fish per <br />test concentration. <br />Exposure medium in each chamber was replaced every 24-hours and organisms surviving <br />at each concentration were counted and recorded. Routine measurements were made of <br />temperature, pH and dissolved oxygen in each concentration, before and after the water change. <br />Test Procedures for Diluted Acute Tests <br />Three additional acute tests were performed to re-confirm the potential for TDS as a <br />source of toxicity in the effluent. These tests were designed to indicate the presence of other <br />contaminants that could be present. <br />The tests were accomplished by making three reconstituted test solutions. Aliquots of the <br />original effluent were diluted to stocks of 50%, 25%, and 12.5%. Each stock solution was then <br />returned to its original state by bringing the alkalinity back to that of the original effluent. <br />Laboratory grade NaHC03 (sodium bicarbonate) was added in order to raise the alkalinity. <br />These reconstituted samples were then run in toxicity tests at concentrations of 100%, 50%, <br />25%, 12.5% and 1.9%. This has the effect of maintaining a constant alkalinity while diluting <br />other contaminants that could be present in the original effluent. In essence, if similaz toxicity is <br />observed in all of the tests, then the alkalinity can be recognized as the cause of the problem. If <br />the toxicity decreases with the increasing dilution of the reconstituted samples, then it can be <br />assumed that some other toxicant is present. <br />Data Analysis <br />Data from the test(s) were analyzed on a personal computer. Where applicable, LC50's <br />were calculated using EPA's TOXDAT Multi-Method Program according to the binomial, probit <br />or moving average methods. <br />The SeaCrest Group 6 <br />