Gas-enhanced in situ thermal treatment for rapid site remediation

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There are tens of thousands of abandoned industrial properties in Canada where soil and groundwater have been contaminated by hazardous organic chemicals. Redevelopment of these brownfield sites is economically and environmentally beneficial to the surrounding communities. However, redevelopment is often limited by the ability of clean-up technologies to remove contaminants, particularly when non-aqueous phase liquids (NAPLs) such as petroleum fuels, chlorinated solvents, and coal tars are present. A class of treatment technologies referred to as in situ thermal treatment (ISTT) can be used to aggressively treat these chemicals in place under conditions where other technologies fail. ISTT technologies heat the subsurface to boil the groundwater and vapourize the contaminants, which are then removed under vacuum as gases. The creation and capture of gases is critical to effective clean-up, but little is known concerning the formation and behaviour of these gases during ISTT or about methods to manipulate gases to increase treatment efficiency. This research will conduct detailed laboratory experiments to study gases that are created during electrical resistance heating (ERH), which is one commonly employed ISTT technology. Both the rate of gas production and its distribution in the subsurface will be assessed, and techniques will be developed to promote gas development and accelerate contaminant removal. Experiments will also be conducted to assess the impact of ERH on bioremediation, and the potential for microbes to produce gases during this process. In addition to experiments, computer programs will be developed to simulate gas bubble formation and movement as the subsurface is heated, and simulate the effect of temperature on bioremediation. The research will be guided by a team of university researchers, environmental engineering consultants, industry partners, and regulators, and will be conducted by four Masters and two Doctoral graduate students. The research results are expected to immediately benefit the partners through improved system design for remediation and help site owners, property developers and municipalities to rapidly remediate difficult-to-treat brownfield sites.