CRYOFRONT: News and Views from the Far North
My 2010 northern infrastructure ‘flight of fancy’ By Ken Johnson, NTWWA Director
Views from Dawson City Dawson City, as seen from the Dome Lookout, remains a challenging location for the construction, and operation and maintenance of water and sewer infrastructure even 100 years after it was first established during the Klondike Gold Rush. The water supply source is a series of wells along the Yukon River, immediately downstream of the Klondike River, which allows the community to capture the cleaner water from the Klondike River watershed rather than the siltladen Yukon River. Work is being completed to determine the extent of the surface water influence on the well system, and what future action is needed to provide well head protection.
The first wastewater treatment system for Dawson City was constructed 30 years ago, and the community is in the process of constructing a new wastewater treatment system. A process technology called “Vertreat,” an abbreviation for “vertical treatment,” was designed by Noram Engineering and Constructors Ltd. and utilizes two 100-metre deep, 1-metre in diameter shafts as the bioreactors. Tunnelling is being completed by Construction Drilling Inc. (CDI). CDI also had to complete a pre-grouting program around the shafts (shown underway in the photo) in order to stabilize the bedrock formation before the drilling could proceed. 24 | Western Canada Water | Winter 2010
Dawson City has been using gaseous chlorine for drinking water disinfection for over 30 years. This technology is preferred by the municipal operating staff because of their familiarity with using the chemical, and equally important, the logistics for delivery and storage in Dawson’s remote location. However, Public Works Manager Norm Carlson recognized the inherent risks of operating a chlorine gas disinfection system, and advanced a building addition to the water supply facility to provide a discrete enclosure for the chlorination system, as well as a chlorine scrubber unit. The work on the building addition (foundation construction underway in the photo) and the commissioning of the scrubber unit was completed in November.
Views from Inuvik The Town of Inuvik was originally serviced in the late 1950s with an above ground water and sewer utilidor system supported on timber piles and protected with a metal cladding. The original system is being incrementally replaced with discrete water and sewer pipes supported on a steel pipe system (as shown in the photo). The thermal stability of the piles is maximized by placing the piles to a minimum of 6 metres into the ground. The piles are coated with heavy grease and wrapped with polyethylene to maintain a non bonding surface between the ground and the pile for the inevitable shifting of the ground.
The pipe used for the sewer and water system of the utilidor is an insulated steel pipe with a metal jacket covering 50 mm of urethane insulation. Urecon is the supplier of the insulated pipe to Inuvik, and many other places across the north. The pipe is insulated at the Urecon shop in Calmar, Alberta and shipped by truck from Edmonton to Whitehorse, and then up Klondike and Dempster highways to Inuvik. In the photo, newly arrived sections of insulated pipe, waiting to be installed as part of the 2010 replacement project, sit beside a section of the original utilidor with its metal clad exterior. The original utilidor system in the Town of Inuvik was supported on timber piles, and it was expected that the timber piles would last indefinitely because of the extremely cold air and ground conditions. However, wood will eventually decompose in the Arctic if exposed to warm temperatures and moisture, even with only the brief periods of exposure during the summer months. The timber pile system is being systematically replaced with the replacement of the utilidor itself; however in some instances the deteriorating timber pile system is being supported by a secondary wood frame system. Click here to return to Table of Contents
Views from Norman Wells
acid before coating the pipe with epoxy. The successful completion of the 2002 project on the Town’s above ground section prompted the Town to advance a similar project on the buried section, which involved discrete excavations of the systems (excavation of insulated fire hydrant beside sewer main shown in photo).
KEN JOHNSON is a consulting engineer and planner, a jazz enthusiast, and a “cool guy” by virtue of the fact that he has been working in the far north for over 20 years. He may be reached at ken.johnson@cryofront.com.
The Town of Norman Wells commissioned a new water storage tank in the past two years. This new larger water storage tank (shown in photo) replaced an aging structure that was at the end of its service life. The new tank utilizes thermal siphons (tall piping shown in photo) to maintain thermal stability of the underlying permafrost. A project undertaken in 2010 was the demolition of the old water tank. The raw water supply for Norman Wells is the Mackenzie River which is quite turbid during the summer months and therefore requires treatment using a conventional package treatment system.
The major project underway in Norman Wells in 2010 is the buried waterline rehabilitation. The schedule 80 pipe was originally installed in the mid-‘70s and remains structurally sound with its 12 mm thick walls. A pipeline rehabilitation program was initiated in 2002 using the oilfield technology of ‘repiping,’ which employs a cleaning process with pigs and ultimately Click here to return to Table of Contents
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