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- Mountain Coal Company CO-0038776 SCG Project No.: 304181 <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. <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 />Data Analysis <br />Data from the test(s) were analyzed on a Pentium® personal computer. Where applicable, <br />LC50's were calculated using EPA's TOXDAT Multi-Method Program according to the <br />binomial, probit or moving average methods. <br />RESULTS <br />The data sheets for the acute tests are located in Appendix 2. See Table 1 for survival <br />and LC50 concentration calculations. <br />Survival in the Daphnia magna test using undiluted effluent was 45% in the 100% <br />effluent and ranged from 70-100% in the remaining effluent concentrations. Control survival <br />was 100%. <br />In the acute test diluted to 12.5% effluent, survival was 5% in the 100% effluent <br />concentration. In the remaining effluent concentrations survival ranged from 80-100%. Control <br />survival was 95%. <br />In the acute test diluted to 25% effluent, survival was 20% in the 100% effluent <br />concentration and ranged from 95-100% in the remaining concentrations. Control survival was <br />100%. <br />In the acute test diluted to 50% effluent, survival was 15% in the 100% effluent <br />concentration and ranged from 80-95% in the remaining concentrations. Control survival was <br />100%. <br />Table 1: Survival and LC50 Calculations <br />` ~ ~ <br />~ <br />3 ~ Z°~~~p ~s ~'' SU RVIVAL TO~TALS <br />m~w;a~.~ s(outr'of 0) <br />me a <br />. <br />a <br />Concentration °lo~ <br />~~ ~. ~~ '".. <br />~ ~ ~ ° ~" "~` <br />~„., `Dilute ~~~ ° `'"~' " <br />tl and atllustetl efflu "~ ~z~~-~.-z <br />enfs~ a« *~~ <br />y <br />(Effluent)„~ ~~ntrea t <br />ed Ee <br />nt~ 50°10 <br />?' <br />` ~' X25% ~'~~' , <br />12 5"10 *~;. <br />~'~ <br />$ am <br />~ ,, ._ <br />. ~ ~ <br />~ <br />100 9 3 4 1 <br />50 14 16 20 16 <br />25 16 19 20 18 <br />12.5 18 18 20 19 <br />1.9 20 19 19 20 <br />Control 20 20 20 19 <br />i^ LC50 ~< s ~'~ 89.3% 68.5% 80.6% 64.6% <br />v ~95°loLlmlt,.S*x..,-~„ 55.8-267 50.0-100.0 50.0-100.0 50-100 <br />The SeaCrest Group, LLC 6 <br />