DEW CLEAN-UP

UMA ENGINEERING; EBA ENGINEERING CONSULTANTS; SGE GROUP; LDS CONSULTANTS

Consulting engineers are helping to deal with acres of contaminated military waste left in Canada’s Arctic after the Cold War.

With U.S. President George W. Bush relaunching the idea of building a Star Wars II laser missile shield, North Americans are again thinking about our lines of defence. However, Canada’s Far North is still coping with the vestiges of earlier military defence operations — the Distant Early Warning (DEW) line sites strung across the Arctic coastline from the Yukon Territory to Baffin Island. The radar defence shield was built during the Cold War to provide early notice of any military invasion from the north.

Now that the 40-year old radar technology is outdated, the DEW line sites have fallen out of use. However, the buildings, equipment and materials that the Canadian and American military forces imported during their occupation remain there. Disposing of waste in the Arctic region is an ongoing problem, and not just for the military. There are hundreds of random waste dump sites littering the Arctic region. Harsh weather conditions, the remoteness and short window of time available for transportation during the summer make it is expensive and difficult to ship toxic material south for treatment.

Frozen core containment

Cleaning up the 21 DEW sites owned by Canada’s Department of National Defence is one of Canada’s largest environmental clean-up projects, costing $320 million. Beginning in the early 1990s UMA’s Calgary and Edmonton offices, together with the Environmental Sciences Group of the Royal Military College, have coordinated efforts to deal with the contamination and waste. UMA is prime engineering design consultant. They have been involved in discussions with regulatory and aboriginal groups, and prepared the detailed design drawings and technical specifications for the different sites. EBA Engineering works on the geotechnical components, including geophysical site assessments and design requirements for the landfills. The SGE Group does construction cost estimates, contracting strategy and construction risk assessments.

So far, work at six sites has been completed: Komakuk Beach, Tuktoyaktuk, Nicholson Peninsula, Cape Parry, Cambridge Bay and Cape Hooper.

At some of these sites the approach has been to enclose the contaminated soil using permafrost and a synthetic liner. Such frozen core containment structures were originally developed for holding mine tailings, but this is the first time they have been used for dealing with contaminated waste in the Arctic region.

Keeping the waste frozen reduces the potential for leachate to be generated and to migrate. At some locations existing landfills were adapted, and in others such as Cambridge Bay and Cape Hooper, new disposal facilities are being built. At the perimeter of these sites a berm of saturated compacted silty gravel is constructed around the perimeter. The berm will freeze and become part of the permafrost regime. A synthetic liner is laid in the base and up the slopes of the berm to provide containment during the period before the material freezes. The disposal site is then covered with a synthetic liner, and a layer of gravel. The depth of the gravel layer is determined by EBA’s proprietary geothermal computer analysis tool to ensure it provides enough insulation to keep the contents permanently frozen. As a safety factor, the layer is 40% thicker than required under the predicted average thaw depth, and 10% thicker than for the predicted 1 in 100 year maximum thaw depth occurring over 10 consecutive years. The team is monitoring conditions to ensure there is no contamination. UMA estimated that the on-site containment strategy saved around $15 million on the first three sites they completed.

Resolution Island

Dealing with the much worse contamination on Resolution Island is another matter. This DEW line site near Baffin Island is owned by the Department of Indian Affairs and Northern Develoment. LDS Consultants of Montreal are coordinating the clean-up and have been travelling to the site during the summer season for four years. Once occupied by about 200 people in the U.S. military, the three-kilometre square Resolution site was abandoned in 1972, but is estimated to hold 9,000 tonnes of contaminated waste. Soils have PCBs exceeding 50 ppm, as well as hydrocarbons, mercury, and heavy metals like cobalt and nickel. Any leaks threaten the ocean and natural habitat.

Here the degree of contamination is such that permanent on-site containment is not an option. Instead LDS is working with a local Inuit contractor to excavate the solid material and store it in temporary stockpiles until it can be shipped south to a hazardous waste treatment plant in Quebec. The total cost of that operation is expected to be $50 million.

Project: DEW Line Clean-Up

Client: Department of National Defence/Defence Construction Canada

Prime consultants: UMA Engineering, Calgary (Steve Stowkowy, P.Eng., Tanya Schulz, P.Eng., Roland Merkosky, P.Eng.

Subconsultants: EBA Engineering Consultants, Edmonton (Bill Horne, P.Eng.) Associate consultants: The SGE Group, St. John’s, Nfld. (Al Green, P.Eng.)

Project: Resolution Island DEW Line site clean-up

Client: Qikiqtaaluk Corporation/Department of Indian Affairs and Northern Development

Prime consultants: LDS Consultants, Montreal (Philippe Simon, ing., Simon Desjardins, ing.)