Clean water

Successful In Situ Chemical Oxidation at a Chlorinated Site

Challenge

Antea Group’s client had an active chemical manufacturing facility which had been in operation for over a century and contained manufactured polyvinyl chloride (PVC), among other products. The polymer had been in the facility for a period of time. Detections of vinyl chloride, 1-2 dichloroethane (DCE), trichloroethene (TCE), 1-2 dichloroethane (DCA) and ethylbenzene were discovered in the soil and groundwater at levels requiring active remediation. However, the source of the contamination was at a location used for manufacturing. Excavation to remove the source would disrupt business and potentially interfere with the structural integrity of above and below grade manufacturing infrastructure.

Solution

The scope of work for Antea Group entailed:

  • Developing appropriate remedial objectives
  • Conducting a feasibility study to evaluate applicable remedial alternatives
  • Selecting a remedial solution to degrade the Chlorinated Volatile Organic Compounds (CVOCs) to below standards for industrial land use and to mitigate further leaching to groundwater
  • Conducting bench and pilot treatability studies 
  • Installing, operating, and monitoring the effectiveness of the remedy
  • Applying land use deed restriction
  • Providing MassDEP Licensed Site Professional (LSP) oversight

Full scale implementation of in situ chemical oxidation (ISCO), using sodium permanganate was performed to remediate the site. The work consisted of nearly sixty injection points at ten foot centers. Sodium permanganate was selected over other ISCO products because it is compatible with steel and plastic and does not release gas or create heat during reaction with contaminants. Sodium permanganate is also easy to detect in monitoring wells due to the dark purple color it maintains until reacting with contamination. 

Result 

Three injection events over the course of four years reduced CVOC sources to below standards and groundwater CVOC concentrations to acceptable levels by 2006.  As of 2016, CVOCs are no longer detectable.

Closure for Antea Group’s client was achieved upon completion of an industrial use deed restriction. There was also an added requirement of indoor air evaluations for new building construction.

Although the radius of influence (ROI) was five feet with pressures at 30 PSI during pilot study, the injection pressure to achieve the desired ROI was much greater at other locations. The final injection event for Antea Group’s client was completed at thirty new injection well locations between the initial injection wells, and the injection pressure was increased to 130 PSI. In the future, the client could consider expanding the activities to more than one pilot location or consider equipment with a wider range of injection pressures.