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W.E. r. Inc. <br />~~r 6 Envlronmenral Tistlae Inc 23S Wes1100 Sauth, Amerlean Fork. Utnh 86003 /8011763-0660 <br />January 8, 2002 <br />Western Fuels <br />Attn: Tony Adkins <br />P.O. Box 628 <br />Nucla, Colorado 81424 <br />re: Potential cause of failure at site 008 <br />Dear Tony, <br />Following our discussion yesterday concerning the acute Ceriodaphnia failure at site 008 I have <br />put together a summary of our observations and thoughts concerning the cause of the toxicity. <br />Stte and I~Istorlcai Suttttnary <br />First is a brief summary of the sample site as I understand it. At the down dip end of the on- <br />surface coal mine ground water is entering the mine and is immediately collected and pumped <br />out. Half of this flow is currently being pumped into pond number 007 and the other half is <br />pumped directly to the discharge point. This ground water has a TDS value of approximately <br />4,000 mg/L and has a pH around 7.0, Pond 007 has been tested routinely for the past few years <br />and has passed repeatedly. Pond 007 was tcstcd side by sidc with pond 008 in December and <br />again passed. Pond 008 was tested for the first time in December resulting in a failure. The <br />subsequent accelerated test #1, also resulted in a failure with an LC50 at 68.3%. <br />Lab Observations <br />During the initial acute toxicity test it was noted by the laboratory technicians that a fuzzy white <br />layer formed on the surface of the l00% concentration. The pH was also monitored and drifted <br />from an initial pH of 7.18 to 8.13 over a 24 hour period. The 008 site had a measured hardness <br />of 2,667 mg/L with an alkalinity of 500 mg/L, <br />It is our experience that the fuzzy layer forrning on the surface is due to the formation of calcium <br />carbonate solids in the sample. This is common in samples which have high hardness associated <br />with high alkalinity. The formation of this solid is enhanced by raising the pH. A common <br />treatment to remove high TDS when major components of the TDS is hardness and alkalinity is <br />to raise the pEI of the sample over pH 10.0, yielding massive precipitation of calcium carbonate. <br />