TCLP

Toxicity Characteristic Leaching Procedure (TCLP) is a laboratory test used to determine whether a waste exhibits the potential to leach hazardous constituents when disposed in a landfill. It is part of the United States Environmental Protection Agency framework under the Resource Conservation and Recovery Act (RCRA) and supports the regulatory identification of wastes that are characterized as hazardous based on their leachability.

The TCLP simulates leaching through a landfill environment by exposing a representative sample to a leaching solution under controlled conditions. The leachate is then analyzed for regulated hazardous constituents, commonly including metals such as arsenic, barium, cadmium, chromium, lead, mercury, selenium, and others. Outcomes are compared to regulatory toxicity characteristic limits; if any constituent exceeds its limit, the waste is deemed to exhibit the toxicity characteristic and is subject to additional disposal restrictions.

Methodology and interpretation are standardized under EPA Method 1311. Sample preparation typically involves reducing the waste to a representative particle size, maintaining it under specified conditions, and performing an extraction with the leachant followed by filtration and chemical analysis of the leachate. The results determine whether the waste is classified as characteristic hazardous and thus requires particular treatment, storage, or disposal pathways.

Limitations of TCLP include its representation of only certain disposal conditions and its sensitivity to factors such as sample heterogeneity, pH, and the specific waste matrix. Consequently, other leaching tests, such as the Synthetic Precipitation Leaching Procedure (SPLP), may be used for alternative scenarios or further characterization. TCLP remains a foundational tool in hazardous waste regulation and compliance.