Performance Evaluation of Remediation Scenarios for DNAPL Contaminated Groundwater Using Analytical Models and Probabilistic Methods

Chlorinated solvents are widespread groundwater contaminants. Treatment or removal of source areas and treatment of the groundwater plume are the two primary strategies used to reduce risks at contaminated sites. Optimal design of groundwater remediation strategies is important to maximize contaminant removal and reduce costs. We used an analytical model and probabilistic methods to evaluate the performance of remedial methods for groundwater contaminated by chlorinated solvents, evaluating different combinations of source removal and plume treatment. The results indicated that natural attenuation alone cannot control dissolved 1,1,1-trichloroethane plumes within the boundaries of the site, with the duration of the plume exceeding 60 years. When 20–80% of the source area was removed, the dissolved plume migrated beyond the site and the plume could not be contained within 50 m down gradient over 20 years. Without source removal, the dissolved plume can only be restricted to within the site by enhanced remediation, and source removal reduces the duration of the dissolved plume. Treatment of the plume shortens the distance over which the dissolved plume travels. When source removal and treatment of the plume were jointly applied, the remediation efficiency of the contaminated groundwater was significantly improved. Analytical models and probabilistic methods have been proven to be very useful tools for optimizing the design of remediation strategies for NAPL-contaminated sites.