EOx Case Study

Combination of EOx with AS/SVE System for Groundwater Remediation in a Gas Station

 

PROBLEM


Benzene and Toluene from a leaking UST had contaminated groundwater at an operating gas station in southern Taiwan. Previous remediation efforts including in situ chemical oxidation (ISCO), air sparging and soil vapor extraction (AS/SVE) system had been implemented with limited remedial effect.

PROJECT GOAL


•  Control plume migration and recover the mass of contaminants.
•  Enhance biodegradation of Benzene and Toluene.
•  Meet local regulatory standards of Benzene and Toluene in groundwater.

  

 
 

METHODOLOGY


•  A treatment train that applied AS/SVE physical system followed by aerobic bioremediation.
•  Remedial system including horizontal and vertical AS/SVE wells was designed and installed for later injection of EOx.
•  In total 11 AS wells and 5 SVE wells were installed and operated for 8 months before EOx injection.  
•  Bottom-up injection of EOx slurry with Geoprobe® was performed twice within 2 years.
•  DO, ORP, water temperature, EC, pH and water level were monitored every 3 months.

 
 

RESULTS


•  Benzene and Toluene in groundwater was decreased from 5.67 (113 times of regulatory standard) and 13.50 mg/L to under 0.10 and 0.01 mg/L respectively.  
•  Two orders of magnitude reduction in concentration indicated that the treatment train worked well with proper injection design.