Use of Innovative Technology to Remediate a Priority Superfund Site

For over 60 years, the Silresim Chemical Corporation Superfund Site operated as a former oil and fuel storage depot and a solvents reclamation business. The company filed for bankruptcy in 1977, abandoning the facility and leaving behind approximately 1 million gallons of hazardous materials in leaking and decaying drums and bulk tanks.

Working under a fast-track schedule dictated by government stimulus funding deadlines, Nobis was selected to complete a $16 million remedial action that included replacing an interim clay cap with a permanent low permeability cap, and implementing in-situ thermal treatment (ISTT) remedy using electrical resistance heating (ERH) to treat contaminated soil and groundwater.

Nobis implemented a patented Electro-Thermal Dynamic Stripping Process (ET-DSPTM) whereby an electrical current is delivered underground via electrodes, generating heat and boiling off organic vapors that are collected through a series of vacuum extraction wells


  • During a constructability review, Nobis identified design deficiencies in the proposed capping system and overall site grading plan.
  • The site was small and required Nobis to install ISTT components with portions of the site that overlapped into the areas of proposed cap construction.
  • An insufficient source of electricity existed near to the site jeopardizing the operating the thermal treatment systems.
  • An unusually high level of groundwater compounded by extremely tight soils decreased the available unsaturated zone, reduced vapor extraction capabilities, and created pressure events.


  • Nobis designed and implemented a series of cap construction alternatives without impact to the original construction schedule.
  • Nobis developed a sequenced construction schedule which allowed for the disposal of on-site contaminated soil generated during the thermal treatment system construction to be placed below the final cap, thus eliminating the need for off-site disposal. In addition, Nobis determined that a majority of the on-site soil from the interim cap could be reused in final cap construction, thus reducing the volume of material needing to be purchased and transported to the site.
  • Nobis proactively coordinated with National Grid to have a temporary 6MW transmission line extended to the site without impacts to the project schedule.
  • Nobis installed additional vapor wells to increase extraction rates and multi-phase wells to lower the groundwater table and remove vapors.


Nobis achieved the overall treatment and operational goals set for this project and met the overall project schedule and stimulus funding requirement. The in-situ thermal treatment system provided very favorable results compared to traditional remedial strategies. Prior to this project, the existing groundwater pump and treat system had removed a total of 225,000 lbs of contaminants in 16 years. By comparison, this project successfully removed approximately 87,000 lbs of contaminants in 9 months, significantly reducing site contamination, accelerating overall cleanup goals, and saving future remedial time and costs to the tax payer.

The Silresim Superfund Site is located within an urban area targeted for future investment and redevelopment. These successful remedial efforts implemented by Nobis bring this site one step closer to being redeveloped.