Edward R. Bates

Long-term performance of aged waste forms treated by stabilization/solidification

Current regulatory testing of stabilized/solidified (S/S) soils is based on short-term performance tests and is insufficient to determine their long-term stability or expected service life. In view of this, and the significant lack of data on long-term field performance in the literature, S/S material has been extracted from full-scale remedial operations and examined using a variety of analytical techniques to evaluate field performance. The results, including those from X-ray analytical techniques, optical and electron microscopy and leaching tests are presented and discussed. The microstructure of retrieved samples was found to be analogous to other cement-based materials, but varied according to the soil type, the contaminants present, the treatment applied and the field exposure conditions. Summary of the key microstructural features in the USA and UK is presented in this work. The work has shown that during 16 years of service the S/S wastes investigated performed satisfactorily.

Chemical stabilization of mixed organic and metal compounds : EPA SITE program demonstration of the silicate technology corporation process

In November 1990, the Silicate Technology Corporations (STC) proprietary process for treating soil contaminated with toxic semivolatile organic and inorganic contaminants was evaluated in a Superfund Innovative Technology Evaluation (SITE) field demonstration at the Selma Pressure Treating (SPT) wood preserving site in Selma, California. The SPT site was contaminated principally with pentachlorophenol (PCP) and arsenic, as well as lesser amounts of chromium and copper. Because of their importance when selecting a remedy for the site, PCP and arsenic were identified as critical analytes to evaluate the effectiveness of treatment. Evaluation of STCs treatment process was based on contaminant mobility, measured by numerous leaching tests, and structural integrity of the solidified material, measured by physical, engineering, and morphological tests. An economic analysis was also performed, using cost information supplied by STC and supplemented by information generated during the demonstration. Conclusions...

Designing treatability studies for CERCLA sites : three critical issues

A great urgency has developed in the past few years within the U.S. EPA remediation program to perform treatability studies at Superfund (CERCLA) sites. The major reasons for this urgency is to ensure the selected treatment technology is applicable to the waste characteristics, and that Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) cleanup goals can be achieved. However, prior to conducting a treatability study, three critical issues must be resolved by the site manager. First, what scale and timing are appropriate? Second, should the treatability study be performed by a treatment technology vendor using proprietary equipment and processes, or can a generic study be performed? Third, should the study be performed in the field or should the waste be taken to the laboratory for testing? The objectives of the treatability study will have a major impact on how these issues are resolved. This paper discusses these major issues and provides information for the design and conduct...