A Comparative Evaluation of Two Extraction Procedures: The TCLP and the EP

The 1984 amendments to the Resource Conservation and Recovery Act RCRA require that the U.S. Environmental Protection Agency EPA restrict the land disposal of hazardous wastes. The EPA has identified four characteristics that could be used to classify a waste as hazardous corrosivity, ignitability, reactivity, and toxicity. A waste exhibiting any one of these properties is classified as hazardous. The Extraction Procedure Toxicity Characteristic EP test is used to determine if a waste poses an unacceptable risk to ground water if improperly managed and therefore should be managed as a hazardous waste. Regulatory thresholds, based on the EP test, have been established for eight metals, four pesticides, and two herbicides. The Toxicity Characteristic Leaching Procedure TCLP EPA Method 1311 was developed to address a Congressional mandate to identify additional characteristics of wastes, primarily organic constituents that may pose a threat to the environment. The TCLP has been promulgated for use in determining specific treatment standards associated with the land disposal restrictions of RCRA. The TCLP has also been proposed as a replacement procedure for the EP test. Using the TCLP procedure, the EPA has also proposed to expand with hazardous waste regulatory levels the list of contaminants from the 14 listed in the EP protocol to a total of 52. The additional contaminants include 20 volatile organics, 16 semivolatile organics, and 2 pesticides. The purpose of this study was to compare the results of the TCLP with those of the EP.