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Client: Mountain Coal Company CO - 0038766 Site: West Elk Mine 017 RESULTS SCG Project No.: 305112 The data sheets for the acute tests aze located in Appendix 2. Table 1 summarizes the results of Daphnia magna tests with the treated and untreated effluent. All treated effluents reported LCSOs within 5% of the untreated LC50 result. Table 1. Daphnia magna survival and LC50 calculations for treated/untreated effluent. t4: a~;~,~.,~* ~'~,t~"t" ~ "~~SURV.11/ALTOTALS~ (OUt~0 20)t` "" ~ "~~ ,~ ~ ` * ~ ~ ~ s , ,r sr.." Concentraf~on~%ff~ t „ ,~ ;~ , x'~~~~ ~,u~` ~r ~ ~'_~ Treated EfFluenfs =~ (Efflue`nfj r ~ _ ~ ~ ~ ~ Untreated Ef(IueriM ~ ~?; : 50%~ = ~ ~ ~ 25% f " 125% ~ ;a'- ~ . n .. _ _ ._.- ..:.. 100 3 4 2 3 50 10 10 9 9 25 19 18 19 18 12.5 20 20 19 20 1.9 20 20 20 19 Control 20 20 19 20 a LC50:=" 54 3% 54 8% 56 3% 55 6% ~ . . . . Survival in the Fathead minnow test was 83% in the 100% effluent concentration. All remaining concentration survival ranged from 78%-88%. Control survival was 98%. DISCUSSION The sample collection showed the effects of toxicity to Daphnia magna in both the treated and untreated effluent samples. The discharge fails WET (Whole Effluent Toxicity) test guidelines for this species for this sampling period. No significant toxicity was measured in the Fathead minnow test. The sample passes WET requirements for this species for this sampling period. A series of tests were performed in conjunction with the original effluent as part of the permit requirements to confirm the effects of TDS against other possible contaminants. The tests appeazed to confirm that TDS, in the form of alkalinity, is the most obvious source of toxicity in the West Elk Mine 017 dischazge. The SeaCrest Group 7