Using Treatment Train to Optimize DNAPL Source Zone Remediation
Many DNAPL sites have been treated using innovative source reduction technologies, such as in situ chemical oxidation (ISCO). Although individual technologies can be successful in removing significant mass from a DNAPL source, rarely, if ever, will implementation of a single technology achieve site closeout. More often, a combination of technologies sequenced throughout the life cycle of a project or applied to different target treatment zones within the contaminated area is used to meet remedial action objectives (RAOs). An example of this is the treatment train approach used when ISCO is used for source treatment purposes. As an emerging technology in the mid- to late-1990s, ISCO was considered a viable method to remediate DNAPL sites successfully and achieve a high level of source area reduction and site closure. However, post-remediation monitoring of these sites often showed a rebound of contaminant concentrations over time. As a result, many of these sites often have to be re-engineered or optimized to define the next course of action. This paper presents the remedial process optimization (RPO) approach used to assess the effectiveness of ISCO and to develop a treatment train approach designed to meet RAOs at the former Orlando Naval Training Center (NTC), Study Area 17 (SA17) site.