2008-10-22_REPORT - C1981008 (3)

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• Narrative and Discussion September 23, 2008 PERMIT AND SAMPLE INFORMATION • NPDES permit * Type of sample: Date and time of sample(s): Date and time of test start: Dilution water: Receiving temperature(s): CO-0000213 Effluent Grab 09/15/0812:20 09116/08 11:30 Reconstituted Laboratory Water 10.5 °C • TEST ORGANISMS Fathead minnow Ceriodaphnia dubia Age: 4 days Age: 2-8 hrs • PROCEDURE Acute, 48 and 96-hour bioassays as outlined in the most recent protocols specified by the Water Quality Control Division of the Colorado Department of Health (1998). • DISCUSSION According to the Western Fuels - Colorado discharge permit (CO-0000213), an acute WET test is failed whenever the LC5o, which represents an estimate of the effluent concentration which is lethal to 50% of the test organisms in the time period prescribed by the test, is found to be less than or equal to 100% effluent. By this definition, the results of this bioassay indicate that effluent from outfall 011 is acutely toxic to fathead minnow but is not acutely toxic to Ceriodaphnia dubia survival. Therefore, outfall 011 may not be in compliance with the acute WET portion of its Colorado State Industrial General Minimal Discharge Permit for the third quarter of 2008. • DATE OF REPORT Re repared by: Stele Gre9n Alawkins Supervis Bi ay Labors ory Date • 4