In situ bioremediation of a diesel fuel spill in northern Manitoba

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Hryhoruk, Clark D.
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A pilot in situ bioremediation project was conducted at the Flin Flon Airport to evaluate the applicability of this technology in a cold northern climate. The site was contaminated with diesel fuel and confined within the unsaturated zone in silt and silty-sand. A two-phase remediation process was designed and implemented: a ground surface spray system and a pump-cycle system. Ground surface spraying involved mixing nutrients (ammonium-nitrogen and orthophosphate) with water in a tank and then spraying the mixture on the ground surface above the diesel plume. The pump-cycle system involved pumping groundwater from below the diesel plume into one of two tanks in series. The groundwater underwent both nutrient addition (weekly) and aeration in the tanks; then it was pumped into eight feeder wells which circumscribed an extraction well. Soil testing revealed that both remediation processes aided in increasing subsurface nutrient concentrations and the moisture content within the diesel plume. Also, high total coliform counts were observed in both the silt and silty-sand layers. Thus implying that conditions for suitable bioremediation can be developed in relatively fine grained soil. Intermittent soil sampling at three locations over a 14 month period revealed that the diesel plume decreased in size by about 30%; contaminant concentrations (diesel fuel) also decreased. Plume movement also occurred. The pump-cycle system remains operational.