The closure of coal mines and associated processing facilities presents many challenges, including the management of contaminant chemicals that may have been released over a potentially long and varied history of industrial activity at a site. However, the high carbon content of coal waste material that may be present at some facilities can actually facilitate site closure by decreasing the mobility of organic contaminants. The Coleman Collieries facility, located in the Municipality of Crowsnest Pass in south west Alberta, Canada operated for approximately 80 years as a coal mining and processing facility. During that time, coal waste and unmarketable coal fines from settling ponds were placed over much of the facility to a depth of 3-4 m. The Province of Alberta, like many jurisdictions, uses risk-based soil guidelines as one of the criteria in assessing whether land, such as a former mine facility, is suitable for a proposed post-closure use. Assessment of the Coleman facility found a range of contaminants exceeding Alberta's default soil guidelines including benzene, toluene, ethylbenzene, and xylenes (BTEX) and other hydrocarbon compounds and fractions. Alberta's soil guidelines were developed to be protective of a range of exposure pathways including vapour migration into indoor air spaces and groundwater transport to potential aquifers or surface water bodies. However, these guidelines were developed based on the expected mobility of organic compounds in typical subsoils with low organic carbon contents. Site-specific soil guidelines were developed for the Coleman facility which took into account the much higher carbon content of soils at this facility, to more accurately determine the remedial actions required for site closure.
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