Diesel spills under stilted buildings in Canadian Arctic villages: what is the best remediation method?

In remote communities in the Canadian Arctic, petroleum hydrocarbons supply most household energy needs. Their transportation and use frequently incurs small volume spills in populated areas. The remediation method that is currently used when such spills affect the soil under northern villages’ stilted buildings is expensive and not well suited to local conditions. Here, we review local constraints and environmental considerations and select the best remediation technology for this context: in situ chemical oxidation, involving sodium persulfate (SPS) alkali activated with calcium peroxide (CP). Activated SPS presents a good reactivity and amenability to compounds found in diesel. Its high persistence allows a gradual contaminant degradation, regulating heat release from exothermic reactions associated with the oxidative reactions. CP provides suitable alkali activation, acts itself as an oxidant and provides O2 into the subsurface, which may favour a final smoothing bioremediation step. The SPS properties and the contaminant amenability mean that diesel is removed relatively efficiently, while the subsurface temperature increase is limited, thus preserving the residual permafrost. The solid form of the chemicals offers safe and economic transportation and operation, along with versatility regarding the preparation and distribution of the oxidizing solution into the subsurface. Finally, the oxidation by-products resulting from this method are not considered to be environmentally problematic in the context of the application, and they can be partly confined during the treatment.