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COMMERCIAL TESTING & ENGINEERING CO. ~1~ DISCUSSION In August of 1996 a Toxicity Identification Evaluation (TIE) was performed on effluent waters from the Bear Coal Company mine site. The results of that TIE indicated that Total Dissolved J Solids, possibly in solution with bicarbonate, were causing toxicity towards Ceriodaphnia cfirbia. In January of 2000 a Preliminary Toxicity Identification (PTI) was performed on effluent waters from the Bear Coal Company mine site. The results of that PTI indicated that Total Dissolved Solids, possibly in solution with bicarbonate, were causing toxicity towards Ceriodaphrtia d:rbia. Upon reviewing effluent chemical data from the previous TIE and PTI and comparing it with current effluent chemical data, CT&E decided to run a more simplified series of tests (PTI) geared specifically towards reconfirming TDS toxicity. Only one of the tests performed in this Preliminary Toxicity Identification removed toxicity. That was the acid/base ion exchange resin test. Most of the tests performed did not significantly decrease toxicity in the Bear Coal Company effluent, with the possible exception of the filtration/no pH adjustment (pH ]0) and the post Cis SPE column (pHi) tests. However, the following observations were made that indicate Total Dissolved Solids may be the source of toxicity: • The pH adjustment tests (both filtration and aeration) did not remove or significantly reduce toxicity. This is an indication of TDS toxicity (USEPA 1992). • A precipitate was not visible in the pH adjustment test, filtration/pH adjustment test, and aeration/pH adjustment test. This is an indication of TDS toxicity (USEPA 1992). • There was no change in toxicity with both the EDTA addition test and sodium thiosulfate addition test. This is an indication of TDS toxicity (iJSEPA 1992). EDTA has a strong affinity for and complexes with cationic metals so that they are not bioavailable. Sodium 7 thiosulfate oxidizes cationic metals so that they are not bioavailable. • There was no loss of toxicity in the post Cis SPE column test and no change in conductivity measurements. This is an indication of TDS toxicity (USEPA 1992). The function of the post Cis SPE column is to remove cationic metals and reduce toxicity due to inorganic constituents. ^ The post Crs SPE column test had LCso of 75.8% and baseline degradation test had an LCso of 77.5%. • The post C~$ SPE column test had a conductivity of 4780 µmhos/cm while the initial toxicity test had a conductivity of 4790 µmhos/cm. 7 _~ r r-sza