Leachability study of chromium contaminated soils to assess the long-term effectiveness of a remediation technology

The effectiveness of a lime-based treatment remediation technology in mobilizing Cr³⁺ is assessed by conducting Acid Neutralization Capacity (ANC) and Toxicity Characteristic Leaching Procedure (TCLP) experiments. However, another important factor controlling the immobilization of the trivalent chromium present in a solid waste form is the resulting hydraulic conductivity, as it governs the rate of migration of the leaching solution. In the present study, a flow-through leaching test was developed in order to concurrently evaluate the chromium release, ANC and hydraulic conductivity of the solid waste form prior to and following lime treatment. A compacted solid disc was placed in a flexible wall apparatus similar to a flexible-wall permeameter. Leaching solutions, such as acetic acid and distilled water, were passed through the specimen under constant hydraulic head conditions. The results of the present study serve as the basis for the development of a general protocol to be used for the design and the evaluation of the effectiveness of remediation technologies.