Enhanced Anaerobic Bioremediation

Innovative approach to the classic problem of remediating a petroleum impacted site achieved success in just 3.5 years.

A former industrial site in Saskatchewan faced remediation of 3,000 cubic meters of gasoline impacted soil and groundwater. Many rural sites in this condition find themselves abandoned because the expense of remediation by excavation and replacement proves too high for the land ever to be viable for sale for future use.

Abandoned former petrol stations with significant environmental liabilities can be found in nearly every community. These abandoned sites can be an eyesore, pose environmental risks to the community, tie up otherwise useful real estate, and reduce taxes payable to all levels of government. They also do not provide employment opportunities.

To overcome this, a new approach was taken to avoid the need for conventional excavation and replacement, potentially saving 90% of the typical cost of remediation. If successful, this means that without environmental liability attached to the property, future owners can redevelop the site as they see fit.

It was decided to pursue an enhanced anaerobic bioremediation approach by adding potassium sulphate within the bottom of an excavation needed to remove existing fuel tanks in the north portion of the Site. In order to ensure full treatment of the plume, a permeable reactive barrier (PRB) was installed near the southern property line which was
close to the leading edge of the plume.

The treatment would be used to intercept and remove PHCs through sulphate-reducing bacteria (SRB) from the groundwater and soil within the treatment area. SRB can consume
sulphate (SO4) rather than oxygen (O2). If a sulphate source is added, the SRB can utilize it and speed up the rate at which the carbon source is consumed or degraded. In this case, the carbon source for the bacteria was the subsurface gasoline plume.

The use of this approach allowed for safe use of the business by the public by limiting the scope of invasive work at the Site. The owner and community benefited from the continued operation of the business throughout the remediation process.

Along with dramatically reducing the cost and time involved in remediation, this approach also reduced the carbon footprint of the total onsite remediation and mobilisations to the site were significantly fewer than if a conventional remedial technique was used.