Gas Station Soil Treatment in Toronto, Canada

Site Summary:

After the removal of a leaking tank and the surrounding soils, Petrox was used to treat soils adjacent to a storm sewer pipe contaminated with residual petroleum constituents. Petrox was injected into the soil at the top of the pipe and allowed to percolate downward through the contaminated soil to as much as 14 feet deep.

Geology and Hydrogeology

The soils were silty clay fill formed from the excavated and recompacted native tills during the installation of the sanitary sewer piping. The soils were moist, but ground water was not encountered within the treatment zone.

Remediation Design

Petrox was injected through 60 injection points covering a plume area of approximately 5,000 square feet. Two treatments of four drums of Petrox (220 gallons) were completed between June and July 2006. After the first Petrox injection, 50 pounds of calcium peroxide was added in a water-based slurry to provide supplemental dissolved oxygen.

Soil sampling was completed in August 2006 to assess the results. Soil samples taken from numerous locations prior to treatment exceeded the regulatory standard. The post-treatment samples were taken from the same depths as close as possible to the original sampling location. At many of the locations the cleanup goals were achieved after the two inoculations. In some locations, however, the contamination was still present above the goals. As a result, another round of sampling is pending.

Please refer to the following table for the soil testing results at a representative location.

Concentrations in µg/kg (ppb)

Results

The results show that Petrox was effective at reducing booth the aromatic BTEX compounds and the heavier hydrocarbon fraction contaminants.

The cost for Petrox used in this project was $7,000.