Chlorinated ethene source remediation: lessons learned

Area of Science:

• Environmental Science
• Hydrogeology
• Remediation Engineering

Background:

• Chlorinated solvents like trichloroethene (TCE) and tetrachloroethene (PCE) are common groundwater contaminants.
• These solvents often exist as dense nonaqueous phase liquids (DNAPLs), posing significant remediation challenges, especially in source zones.

Purpose of the Study:

• To review advancements in DNAPL source zone remediation over the last decade.
• To highlight practical lessons learned for improving remediation strategies.

Main Methods:

• Review of existing literature and case studies on DNAPL source zone remediation.
• Analysis of the effectiveness of various remediation technologies, including injection-based and thermal treatments.
• Evaluation of performance metrics, such as mass discharge, for assessing remediation success.

Main Results:

• Complete groundwater restoration is seldom achieved; partial restoration using metrics like mass discharge is often more practical.
• Injection-based technologies can reduce contaminant mass and discharge by 1-2 orders of magnitude.
• Thermal treatments can remove substantial mass, but residual contamination typically remains.

Conclusions:

• A combination of technologies tailored to specific site conditions and remediation phases is often necessary.
• Future research should focus on improved delivery and characterization techniques.
• Site managers must plan for long-term management of residual contamination post-source treatment.