Evaluation of batch leaching procedures for estimating metal mobility in glaciated soils

Batch leaching methods have been used for several decades to estimate the potential release of contaminants from soils. Four batch leaching procedures (toxicity characteristic leaching procedure, synthetic precipitation leaching procedure, deionized water leaching procedure, and California waste extraction test) were evaluated for their ability to realistically quantify the mobility of metals from previously contaminated glaciated soils. The study was conducted using soils from four different sites (three in Connecticut and one in Maine). The results of the batch leaching procedures were compared with a set of continuous column leaching experiments performed at two different flowrates and two influent pH values. The results suggested that the synthetic precipitation leaching procedure (SPLP) was more realistic than the toxicity characteristic leaching procedure (TCLP), but still a conservative leaching estimate for evaluating the potential for metal mobility in glaciated soils. This study suggests that using SPLP as a test for estimating metal cleanup levels will result in lower remediation costs relative to TCLP or waste extraction test (WET), but still maintain a high level of confidence in the protection of ground water quality.