Case Study 97-06: Bioremediation of Soil Contaminated with Diesel Fuel at Remote Fly-In Sites

This project was conducted in remote northern Ontario. The contaminated sites were accessible only by float plane. Had road access been available, the contaminated soil could have simply been excavated and removed to a secure landfill however, in this case the challenge was not only how to remove the contamination but also how to complete the job using only equipment that could fit through the door of a float plane (about 1 metre by 1 metre). The only viable approach was bioremediation; the use of naturally occurring soil micro-organisms to degrade the fuel.

The extent and exact location of contamination were unknown. Phase 2 property audits were performed to locate the contamination. Representative samples were collected and soil was analyzed in our laboratory to determine both the concentration level of diesel and the extent/direction of the contamination at the different sites (Click here to learn more about the importance of good sampling technique). Literature searches were conducted in order to determine established cleanup thresholds, as well as guidelines for clean up methods and analyses. 

In the second season, the Phase 3 cleanup was begun. Surface contaminated soil was moved to a central location for treatment, while contamination at depth was left in-situ and tended during the short summer. Samples from the in-situ sites were taken by a split-spoon method using a drill specifically modified to allow for shipment in float planes. Sites were visited on a rotating schedule with soil samples collected and shipped back for diesel analysis in our laboratory. 

In support of the field work, lab scale experiments were conducted to identify compounds that could be used as markers for the biological degradation of the fuel. This was an important consideration for our client, who was concerned about verifying that the fuel was being degraded. We successfully identified several metabolites that served as biodegradation markers (read more about biodegradation markers). We also developed workable sampling strategies to give increased assurance that the fuel was in fact degrading.

At the time of this writing, the remediation of many of the sites has been completed. We continue to monitor the remaining sites.