Remediation Status: Site closed

Why the technology was selected:
ISCO was selected for remediation based on the presumption that the initial groundwater encountered at the site was a Class 3 resource.

Date implemented:
June 2010

Final remediation design:
12 temporary injection wells were installed to depths ranging from 19 to 26.5 ft BGS. The injection wells were constructed of 1-inch polyvinyl chloride (PVC) and had either 10 or 15 ft of 0.010-inch slot well screen, depending of well depth. The temporary injection wells were backfilled with
soil cuttings to approximately 2-ft BGS, and then grouted to the surface. The ISCO interim response action led to the injection of more than 2,500 pounds of sodium permanganate into the saturated soils beneath the asphalt parking lot behind the dry cleaners.

Results to date:
ISCO treatment increased the
concentrations of COCs in MW-1 because of the flushing of contaminated water towards the well, but reduced the concentrations of COCs in MW-2 and MW-9. The concentration of PCE increased from 7.2 to 11 mg/L in MW-1, but the concentrations of PCE dcreased from 3.1 to 1.6 mg/L in MW-9 and from 0.78 to 0.097 mg/L in MW-2. Although ISCO treatment is imcomplete, residual permangate was injected into the preferential flow paths in the saturated soils. Although permanganate is stable and retains a capacity for the oxidation migrating water, permanganate is reduced by the natural oxidant demand of the water.

Next Steps:
Because the concentrations of chlorinated VOCs are below the applicable PCLs for surface soil,
subsurface soil, and saturated soil, no further sampling or response actions are warranted.

Cost to Design and Implement:
$73,398.55