Site history indicated that several sources may be present at the site. Chlorinated solvents may have previously been used during equipment maintenance activities conducted at the site, and a drum storage area was present immediately north of the area where high solvent concentrations, predominantly TCE, were reported in soil, gas and ground water. These two areas drained, via surface and subsurface pipes, to a small culvert. A TCE source area was identified at this location.
The Site is underlain by granitic bedrock which is overlain by varying thicknesses of decomposed granite. One area has a layer of colluvium and decomposed granite approximately 30 feet thick comprised of brown and yellowish silty sand deposits. Below the decomposed granite, a zone of fractured granitic bedrock extends to a depth of approximately 70 feet below ground surface (bgs). The degree of weathering decreases with depth and relatively fresh, unweathered zone of granitic bedrock is present to the total depth drilled at the site, approximately 100 feet bgs.
- Heat the entire TTZ to near the boiling point of water, or higher if possible, and maintain this temperature for at least 30 days.
- Continue heating past the period of peak mass removal and long enough to achieve diminishing returns, also called the asymptotic mass removal rate.
- Substantially reduce concentration in all extraction wells prior to ceasing heating.
Challenges & Solutions
The biggest challenge encountered on this project was bringing power to the site in a timely fashion. The solution to this obstacle was to practice continuous communication and to offer any assistance possible to expedite the process.
All project objectives were reached, resulting in the successful completion of the project. The objectives were reached on schedule and within budget.