Evaluation of the toxicity characteristic leaching procedure (TCLP) on utility wastes

Abstract

In April 1985, the U.S. Environmental Protection Agency presented a new method for characterizing wastes, the Toxicity Characteristic Leaching Procedure (TCLP). This method will replace the Extraction Procedure Toxicity Test (EPTC) for determining the toxicity characterisitc of wastes under the Resource Conservation and Recovery Act (RCRA). This study examined 41 electric utility wastes produced by conventional and advanced sulfur dioxide control technologies to obtain information on the performance characteristics of coal combustion wastes tinder TCLP test conditions and to compare the performance of these wastes under both the EPTC and TCLP. The study addressed three aspects of the new test: (a) the effect of increasing the filter pore size from 0.45 microns in the EPTC to 0.7 microns in the TCIP: (h) the effect of changing the chemical nature of the leach medium on the measured values of the inorganic analytes in the leachates; and (c) the levels of organic compounds found in TCLP leachates of the coal combustion residues. The data suggest that filter pore size does not affect leachate composition. As a result, this change should not affect the analysis of conventional coal combustion wastes. An element-by-element comparison indicated that the TCLP is more aggressive than the EPTC towards leaching silver, arsenic, and chromium from the wastes tested, while the EPTC is more aggressive towards barium. The level of TCLP leachable organics associated with the coal combustion waste products was very low. mostly in the low parts-per-billion range.