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Client: Western Fuels <br />Site: New Horizon Mine 007 <br />CO- 0000213 SCG Project No.: 311693.B <br />DISCUSSION <br />A chronic WET test is considered a violation of a permit limitation when both the No <br />Observable Effect Concentration (NOEC) and the IC25 are at any effluent concentration less <br />than the In Stream Waste Concentration (IWC). A chronic WET test is considered to have failed <br />one of the two statistical endpoints when either the NOEC or the IC25 are at any effluent <br />concentration less than the IWC. The IWC for this permit has been determined to be 100% <br />effluent. <br />The Ceriodaphnia dubia test showed an 1C25 for reproduction of 61.7 %. This result is <br />considered a failure of one statistical endpoint. Two consecutive failing reporting periods would <br />result in the need for Division notification. However, since neither WET test meets the defined <br />criteria for violation or consecutive failures, the discharge passes WET (Whole Effluent <br />Toxicity) testing requirements for quarter four 2011. <br />REFERENCES <br />1. Hach Chemical Company. 2008. Hach 's Water Analysis Handbook. Fifth Edition. Hach <br />Chemical Company, Loveland, Colorado. Digital Medium. <br />2. APHA/AWWA/WEF. 1998. Standard Methods for the Examination of Water and <br />Wastewater. 20` Edition. American Public Health Association, Washington, D.C. <br />3. USEPA. 2002. Short Term Methods for Estimating the Chronic Toxicity of Effluents and <br />Receiving Waters to Freshwater Organisms. EPA - 821 -R -02 -013. 335 pp. <br />4. CDPHE (Colorado Department of Public Health and Environment). 1998. Laboratory <br />Guidelines for Conducting Whole Effluent Toxicity Tests. Water Quality Control Division. <br />5. USEPA. 2000. Method of Guidance and Recommendations for Whole Effluent Toxicity <br />(WET) Testing (40 CFR Part 136). EPA/821 /B- 00/004. <br />6. USEPA. 2000. Understanding and Accounting for Method Variability in Whole Effluent <br />Toxicity .4pplications under the National Pollutant Discharge Elimination System Program. <br />EPA/833/R-00/003. <br />SeaCrest Group 9 <br />