By Ken Johnson
The use of piped water distribution systems in the Canadian Arctic is a century old practice that began with an installation in Dawson City, Yukon, in 1905. This system was very rudimentary, but the fundamental practices of freeze protection by heating the water and bleeding the system were applied. Heating was accomplished by running a parallel steam pipe system beside the wood stave pipe water system, which continuously provided a heat source. Bleeding was done with a constant discharge of the water system into the adjacent Yukon River.
The next significant piped water distribution system in the Arctic was constructed for the mining community of Yellowknife in 1950. In the 45 years since the Dawson City system was built, considerable improvements were made in the freeze protection practices.
The Yellowknife water system applied a circulating water system, with provision for heating. A 200 mm iron header fed the system from an intake pumphouse, and the flow was divided into 150 mm laterals, with a 100 mm return pipe to provide recirculation flow.
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Each house had a 12 mm service connection that looped from the 150 mm lateral, returning to a 100 mm return lateral. The return line connection had a small orifice to induce continuous circulation. All of the pipelines were buried with a minimum cover of 1.5 m as a freeze protection measure, and were also insulated using local moss.
The establishment of the new town of Inuvik in 1960, to replace the flood prone community of Aklavik, saw a similar configuration to the freeze protected system in Yellowknife. However, because of the thaw-sensitive permafrost, a decision was made to install the system in an aboveground linear box system, which became known as an “utilidor”. The piping was asbestos cement and the system was recirculating. Heating was provided by the high-pressure district heating system, located in the same utilidor box as the water and sewer piping.
Iqaluit’s original water system copied the system in Inuvik, with an aboveground utilidor using asbestos cement piping. This system also used water tempering, recirculation, and bleeding to protect it from freezing. The construction of the Astro Complex in Iqaluit was the first major development needing a water supply. It was connected to the water distribution system from an aboveground utilidor that originated from the water treatment plant at Lake Geraldine.
Substantial residential growth occurred in Iqaluit in the 1970s and the Territorial Government decided to extend the piped water system. This growth initiated the introduction of buried servicing, which avoided exposure to the extreme cold at the ground surface. The growth also introduced improvements in pipe and manhole materials.
All of the “modern” provisions incorporated into the design of water systems in the Canadian Arctic were in place at the end of the 1970s. These provisions included buried high-density, urethane insulated, polyethylene piping, which was installed as a looped system with water reheating and recirculation.
In the mid-1980s, another substantial expansion of the piped water system in Iqaluit was initiated. This involved the introduction of metal “access vaults” as a replacement for concrete manholes. These structures provided better separation between servicing systems and installation efficiency was substantially improved. Commissioning was also less challenging, because the access vaults could be tested before shipment from the factory in the south.
In the 1990s, the system layouts for recirculation, even for pipe sections that could not easily be looped, were standardized with water pipes looping back on themselves in some cases. A modest increase in cost for the “double piping” of the recirculation loop was offset by a number of benefits. These included reversing the flow in the return line in a fire flow situation, and improving the redundancy of the water supply by using the return line as a supply line in case of a supply line failure. The watermains were also deep enough that seasonal temperature variations that the system was subjected to were small.
Since 1990, remediation and replacement work of earlier systems has been underway. Reliable and accurate flow measurement and monitoring equipment has become far more affordable. While good quality flow measurement/monitoring equipment was available pre-1990, it was extremely expensive and as a result was not commonly used in northern water systems.
In water systems that rely on flow or recirculating flow to provide freeze protection, flow monitoring is critical. The ability to generate alarms or to start standby pumping in the event of a loss of flow has both improved system reliability and simplified the lives of operations staff.
The second major technological advancement has come with improvements in communications technology. Earlier systems may have relied on something as simple as a passerby noticing that the red beacon on the outside of a panel or building was on. Now, telephone, cell phone, satellite, and/or internet-based communications systems provide both continuous equipment monitoring and alarms triggering in the event of abnormal conditions in heating or circulating freeze protection systems.
Modern electronics have also allowed optimization in the control systems. For example, operating systems at closer to 0°C saves on energy for reheating.
The increase in community piped water systems has not expanded a great deal. However, a few communities have received “core” community water systems that service just the larger water users in the centre of the community, such as schools. These systems were developed without any plans for expansion, because of the high capital cost of buried systems in comparison to trucked systems. Another factor is ground movement, as a result of permafrost, that is very hard on buried pipelines and shortens their design life. As the impacts of climate change unfold, ground movement will become worse.
Ken Johnson is with EXP. Email: firstname.lastname@example.org
Read the full article in ES&E Magazine’s August/September 2020 issue: