Abstracts

Self-sustaining Treatment for Active Remediation (STAR) is an emerging remediation
technique which utilizes a subsurface smouldering reaction to destroy non-aqueous phase
liquids (NAPL) in situ. The reaction is self-sustaining in that, once started for a local ignition
point (e.g., well), the destructive front will propagate outwards using only the energy
embedded in the contaminant as long as there is sufficient contamination and delivery of
air. Recent interest from industry has prompted research into lab-scale investigations of
the efficacy of STAR for site specific conditions. Efforts to characterize the subsurface
contamination at numerous former manufactured gas plants (MGPs) have shown that
the coal tar can occur as both a continuous pool as well as in distinct seams separated by
clean layers of varying thickness. STAR should be able to ‘jump’ across clean sand gaps and
propagate a self-sustaining reaction in the contaminated region beyond if enough energy
to reignite is transmitted across the gap. This experimental study evaluates the ability of
STAR to cross clean sand gaps in coal tar contaminated porous media in both one- and
two-dimensional systems. Sensitivity to various in situ and engineering control parameters
are explored including: coal tar layer thickness, soil permeability, moisture content, NAPL
saturation, and air injection flowrate. High resolution thermocouples reveal the progress
of the reaction, continuous gas emissions analysis reveals when the reaction is active and
dormant, and careful excavation map the extent of remediation and whether gaps were
successfully jumped. This is coupled with thermal imaging videos which map the progress
of the front across the gaps. The work has demonstrated that substantial gaps, much larger
than previously anticipated, can indeed be jumped by the reaction (e.g., more than 35 cm,
reaching the limit that can be measured in the laboratory). Also observed was the mobilization
of pre-heated coal tar into some clean gaps and the reaction’s ability to propagate
through and destroy coal tar beside and within the gaps. This work provides new insights
into the robust nature of the technology for in situ applications, and explores the degree of
heterogeneity required before the reaction is impeded and a new ignition location would
be required.
Surficial Geology of Southern Ontario
Wednesday, October 28, 13:00 – 14:40
Chair: David Sharpe
Room: Heritage
231 - Regional buried bedrock valleys, infill sediments and
stratigraphy in southern Ontario: a review
Cunhai Gao
Ontario Geological Survey, Sudbury, Ontario, Canada
Large buried bedrock valleys and depressions in the Great Lakes region have been studied
since the late 19th century. In southern Ontario, they include, notably, broad bedrock
troughs and gorge-like bedrock valleys, e.g., the Laurentian bedrock trough, Erigan valley,
Milverton and Wingham bedrock gorges, and the Dundas valley among many other
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