Summary: ORIN successfully treated chlorinated solvent contaminated groundwater with in-situ chemical oxidation during a pilot study at a former dry cleaning facility. Chlorinated solvent levels were reduced from 10,680 ug/L to less than 3,777 ug/L over a two-month period. ORIN’s approach saved the client approximately $35K over traditional remediation approaches.

Site Characteristics:

  • Site: Former Dry Cleaning Facility near Atlanta, GA.
  • Geology: Clayey silt with sand lenses 12’-24’ bgs
  • Groundwater velocity: average 10-5 cm/sec
  • Contaminants:
    • 6,300 ug/L Tetrachloroethene
    • 2,660 ug/L Trichloroethene
    • 1,720 ug/L Dichloroethene
    • Trace Vinyl Chloride

Remediation Approach:

  • Treatment chemistry: Potassium permanganate (KMnO4) and Sodium permanganate (NaMnO4).
  • Treatment application: Chemical injection through a series of direct push and permanent points.

Chemistries used during injection

Permanganates have been shown to reduce levels of chlorinated solvents in bench level testing prior to field implementation. A benefit of a permanganate remediation approach is the complete reaction of the contaminant without the formation of intermediate compounds commonly found with biodegradation.

Summary of Implementation

The chemistry was designed for the oxidation of chlorinated solvents (PCE, TCE, DCE and degradation products) in the groundwater at the site. The purpose of the pilot study was to provide information on the feasibility and logistics of full-scale treatment. To minimize the costs for multiple injections, ORIN recommended that permanent point injectors be installed horizontally under the building. Five direct push injection points (KMnO4 ) and four permanent injection points (NaMnO4 ) each received 300 gallons of permanganate. NaMnO4 was injected where contamination levels were the highest, including the source area. KMnO4 , being more cost effective, was injected in all other areas to minimize the client’s expense. Evidence of oxidant influence was observed during the injection by the increase of key groundwater parameters such as DO, ORP, pH and conductivity in monitoring wells within the plume.

Effectiveness

Two months following the injection, monitoring wells were purged and sampled for VOC constituents. Average PCE concentrations were reduced from 6,300ug/L to 2,419ug/L within the pilot test area. Down gradient wells outside of active injection area also showed a significant reduction. Full-scale injection will commence in the summer of 2004.

The Bottom Line

ORIN successfully reduced contaminant levels in the pilot study area by injecting permanganate chemistry through a series of injectors over a two-day period. Performing the pilot study demonstrated the effectiveness and feasibility for full-scale injection at this site. Thereby reducing full scale costs by $250K and shortening project timeframe by years over traditional remediation approaches.