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L1~ COMMERCIAL TESTING 8 ENGINEERING CO. <br />e ive~• <br />O a~METHODS <br />A two species acute bioassay was conducted with efluent from New Horizon Mine, outfall 007. <br />An effluent grab sample was collected on October 14, 2002, stored on ice, and delivered to <br />Commercial Testing and Engineering, Co. (CT&E) on the following day. The effluent sample <br />was received at a temperature of 0.0 ° C and assigned CT&E sample tracking number 072-3534- <br />001. The bioassay was initiated approximately 27 hours after sample collection. <br />Testing was conducted in accordance with the most recent protocols specified by the Water <br />Quality Control Division of the Colorado Department of Health (1998), outlined in Table 1. <br />Basic characteristics of the effluent and dilutions were measured as follows: <br />Characteristic Method/Equipment EPA Method <br />Alkalinity <br />J Ammonia <br />J Chlorine, Total Residual <br />Conductivity <br />Dissolved Oxygen <br />Hardness <br />pH <br />Temperature <br />Titrimetric (APHA', 1989) <br />Colorimetric Analysis Method <br />LaMotte STC-Cl Colorimeter <br />Orion Model 160 Cond. Meter <br />Orion Mode1850 DO Meter <br />Titrimetric (APHA, 1989) <br />Fisher Model 925 pH Meter <br />NISTZ calibrated thermometer <br />EPA 310.1 & 130.2 <br />EPA 350.3 <br />EPA accepted <br />EPA 120.1 <br />EPA 360.1 <br />EPA 310.1 & 130.2 <br />EPA 150.1 <br />EPA accepted <br />The tests exposed daphnids, Daphnia magna, to five concentrations of efluent, 100%, 75%, <br />50%, 25%, and 12.5%, prepared using reconstituted laboratory water at 225 mg/L CaC03. <br />Additionally, the tests exposed fathead minnows, Pimephales promelas, to five concentrations of <br />efluent, 100%, 75%, 50%, 25%, and 12.5%, prepared using reconstituted laboratory water at <br />115 mg/L CaCOs. Control replicates were exposed to 100% laboratory water. <br />The Binomial method determined the LCso's', where applicable. Significant differences in <br />mortality were analyzed using Steel's Many-One Rank tests. <br />' American Public Health Association <br />Z National Institute of Standards and Technology <br />' Lethal Concentrations - an estimate of the concentration lethal to 50% of the organisms in the time prescribed by <br />the test <br /> <br />f526 <br />