Coal Gas Legacy

by Ian Edgar Spice, CANVIRO Consultants, Waterloo, Canada,
Richard John Rush, CANVIRO Consultants, Waterloo, Canada,
Robert Brian Whiffin, CANVIRO Consultants, Waterloo, Canada,

Serial Information: Civil Engineering—ASCE, 1989, Vol. 59, Issue 4, Pg. 72-73

Document Type: Feature article


The remains of a former coal gasiication plant were uncovered during redevelopment of a site for the new City Hall in Waterloo, Ont. The coal tar waste was a dense, immiscible tarry fluid containing polynuclear aromatic hydrocarbons. Migration of coal tar was found to be limited to shallow coarse grained fill and alluvial deposits underlain by a silty clay. Cleanup was achieved by conditioning semi-solid contaminated material with fly ash to ease excavation and removal. A tile drain collection system and treatment plant took care of any redissolved contaminants. Coal tar contaminated material was classified based on benzo(a)pyrene concentrations in leachate generated by an acetic acid extraction procedure. Generally, only the wastes with high composition of coal tar were classified as hazardous, to be disposed of at a secure landfill. All other waste went to a municipal landfill. The fast track remediation allowed construction of the City Hall to be completed on schedule.

Subject Headings: Coal | Government buildings | Clays | Pollution | Drainage systems | Hazardous wastes | Landfills | Municipal wastes

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