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| Hall Beach DEW Line site at dusk. |
Of primary concern were PCBs and inorganic elements
By Rebecca Sullivan, UMA Group Ltd.
Innovation has been the key to solving one of the largest environmental clean-up projects in Canada: remediation of over 100 existing landfills and dumpsites resulting from the operation of 21 Distant Early Warning (DEW) Line sites in the Canadian Arctic. The scope of the project includes demolition of existing facilities, removal of contaminated soils and hazardous waste materials, and the development of new landfills for the disposal of waste materials collected during the clean-up.
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| Hall Beach DEW Line site at dusk. |
This innovation, which can be applied to other waste management facilities in the Arctic, won the 2000 UMA Taciuk Innovation Award.
A legacy of the Cold War, the DEW Line sites located at the 66th parallel on the Arctic coastline, from the Yukon Territory to Baffin Island, provided for early detection of military approaches over the North Pole. Advances in radar surveillance have made these facilities redundant. At the time the Canadian Department of National Defence initiated the clean-up of these sites, no other engineered landfills had been developed for the Arctic. Of primary concern were the contaminants -- PCBs and other inorganic elements such as copper, lead and zinc and the effect of their mobility and distribution into the aquatic environment.
UMA's design team evaluated on-site treatment options as well as transporting and disposing of the contaminated soil at facilities located in southern Canada; however, the high cost and environmental risk were too great. Also, site investigations revealed the presence of contaminated leachate (the percolation of water/solute through landfill wastes) and it became necessary to find a way to remediate and mitigate the potential for its migration. The most economical and environmentally sound solution was to design and construct secure on-site facilities for containment and disposal of contaminated soils and waste materials.
UMA's unique design concept uses frozen ground (permafrost) to contain the contaminated waste. Leachate generation is minimized by promoting permafrost formation through the landfill contents by placing an insulating layer of granular material over the landfill. Saturated permafrost creates the primary containment barrier and a secondary system of synthetic liner materials provides containment over the period required for the permafrost to completely encapsulate the landfill contents.
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