Recent findings on immobilization of organics as measured by total constituent analysis

Under the new regulatory test methods and treatment standards used by EPA in the Land Disposal Restrictions, the effectiveness of stabilization is judged primarily by the total constituent analysis (TCA) rather than, as previously, by the Toxicity Characteristic Leaching Procedure (TCLP). It is likely that this approach will be extended to remedial actions in the future. These protocols make it much more difficult to meet the standards by stabilization treatment. As a result, new stabilization additives and formulations are being investigated to meet this challenge. Four cement-based formulations were tested in several studies on soil spiked with 50 hazardous organic compounds representing major EPA and functional classes. Results were compared with the untreated contaminated soil, and with each other. Additives tested included activated carbon, organoclay, and two proprietary rubber particulate additives, KAX-50(TM) and KAX-100(TM). The proprietary additives were found to be superior overall to carbon and organoclay for stabilization of most constituents. For specific constituents any of the additives, or combinations thereof, might be useful. The studies showed that stabilization of low-level organic constituents in soils is feasible, even for volatile organics.