Taku River Tlingit Geothermal

Engineers Canada 2019 Engineering Excellence Award Submission Taku River Tlingit Geothermal Location: Atlin, British Columbia Client: Taku River Tlingit First Nation Completion: October 2018

Background After multiple years of planning and design, Stantec’s team saw a project come to life that impacts the entire community of Atlin, British Columbia and especially the Taku River Tlingit First Nation (TRTFN). Two of the TRTFN’s main buildings in Atlin (the Main Admin Building and the Multipurpose Building) are now being heated and cooled by Atlin Lake, the largest natural lake in the province. The buildings themselves are not new, but the elimination of fossil fuel heating is breathing new life into the buildings and energizing the first nation and community! The Main Admin Building was constructed at least forty years ago, heated with a fuel oil boiler system and saw no cooling for its occupants. It was a mouse- infested run-down dilapidated building used by the first nation to conduct its primary governing operations. The Multipurpose Building was constructed in 2007 with a heating source of water to air heat pumps, sourced by a slinky-coil heat exchanger (miles of PEX tubing in 6’ loops zip tied to orange plastic snow fencing) sunk to the bottom of Atlin Lake. The system worked for only a couple of years when some of the anchors for the lake loops let loose causing the loops to float up and the whole system to fail. The slinky-coils were removed and the building, used for offices and meeting space, was required to function on backup electric heat since then. Project Description Fast forward to mid-2016. The TRTFN was striving for elimination of fossil fuel dependence by expanding its hydroelectric power generation plant and converting many buildings to electric heat. For two of its key buildings, Stantec was retained to help solve the problem of the failed geothermal system and to expand to a second building with the goals of eliminating reliance on fuel oil, replacing equipment that was beyond its expected service life, and increasing heating and cooling efficiency in both buildings. Several options were explored to ultimately end up where we are now; with a single stainless-steel plate and frame lake source heat exchanger installed on a nice flat spot 60 feet underwater in Atlin Lake and an effective, and efficient heating and cooling system in both buildings, and no fossil fuels. The installation of the new system saw the use of a crane loaded onto a barge, the heat exchanger carefully lowered onto piles drilled into the lake floor and secured by divers, and connections made to underground and underwater piping installed from the heat exchanger to both buildings. A new electrical service and upgraded mechanical heat pump systems were provided for the buildings. All fossil fuel equipment, including boilers, chimneys, piping and tanks were removed, and rodent contamination was eliminated. To complete the sustainability picture, a new envelope is planned for the Main Admin building. The result is a state-of-the-art never-before seen in the North heating and cooling system that draws the lions share of its energy from the lake and saw the first nation reach its goals of fossil fuel elimination. In addition, the construction saw the employment of a significant portion of its labour by TRTFN forces thereby boosting the local economy and enabling the TRTFN to maintain the system into the future.

Taku River Tlingit Geothermal 1 Northern Innovation In the North, innovation means designing for cold temperatures, shorter construction seasons, remote locations and unique challenges in material procurement. A few ways that we designed for these are: • Cold Temperatures & Material Procurement for Atlin Lake • Heat Exchanger Foundation: the unknown lake bottom conditions for heat exchanger foundation design saw the need for a pre-design dive and hand driven piles to establish some “ground” condition parameters. Screw piles were designed based on this preliminary data collection. At the same time, determination of a flat spot for location of the equipment was determined. • Heat Exchanger Sizing: lake-bottom temperatures for heat exchanger sizing and to eliminate icing on the plates was needed and unavailable from Environment Canada data. The pre-design dive also provided for a temperature survey. • Heat Transfer Fluid: selection of the heat transfer fluid to eliminate chance of lakewater contamination (Department Fisheries & Oceans permit in effect) required it to be safe, environmentally friendly, non-toxic and have excellent heat transfer properties resulting in the selection of a denatured ethyl alcohol. It also had to be an antifreeze to allow for frigid -40degrees Celsius winter air temperatures and a power outage possibility. • Remote Location: • Skilled Labour: with less than 500 residents in Atlin, the capacity of local skilled labour to carry out this specialized construction is not available. Skilled labour was imported from Whitehorse where cold climate is no stranger, and Vancouver where marine installations are more common. One of TRTFN’s mandates is to employ their own forces where possible so this was made a condition of the tender. • Travel: There is only one road into Atlin, and it is from the Yukon. Most equipment is supplied from the lower mainland of British Columbia and is trucked up the Alaska Highway to the Yukon and then down to Atlin. The diving forces, barge, piles, piping, heat exchanger and heat pumps all traveled long distances to get to their final destination. • Lodging: There is very little lodging available for contractors in Atlin. Locals opened up their homes to accommodate some of the workforce. barge from BC, divers from Vancouver. • Jurisdiction: The project is located in the province of British Columbia on First Nation land and was completed by Yukon based Engineers and Contractors. Although the National Codes were applied, many negotiations with BC based regulators and First Nation regulators were required to determine which authorities presided. • Short Construction Seasons: • Phase 1: In order to be prepared for the spring heat exchanger installation, a preliminary construction contract was provided to allow for the underground piping to be complete in advance of the lake system installation. This was completed in September 2017. • Phase 2: The main contract was awarded in late November 2017. All lake work had to be completed before lake levels were too high in the spring of 2018, requiring an “ice-out” watch to determine when the barge could be scheduled to float. In addition, coordination with BC Hydro for the new power service was required prior to Phase 3. • Phase 3: All heating system upgrades had to be completed in the non-heating season (summer 2018).

Sustainability & Community Impact We are striving to make a difference in the world by improving the communities we live in. This sustainable project actively contributes to the community, has minimal environmental impact, is well-built and designed to last for many generations, is flexible for future uses and repairs, and uses thoughtful material choices. The Taku River Tlingit Geothermal project has integrated all of these. The buildings are central to the first nation community and now exemplify minimal environmental impact with their new fossil fuel free heating and cooling systems. The geothermal system is robust in construction and has a solid foundation on the bottom of the lake, built to last and potentially be expanded to further benefit the community. Stantec Project Team Contractors • Project Manager: Sandy Birrell, P.Eng. TSL Contractors Ltd. • Mechanical Engineers: Sandy Birrell, P.Eng. & Brendan Zrum, P.Eng. HVACTech Systems • Electrical Engineer: Jordan Youngs, P.Eng. Jaytech Electric & Controls • Civil Engineer: Arlen Foster, P.Eng. Terracana Foundation Solutions Inc. • Structural Engineer: Michael White, P.Eng. Omega Thermo Products • Marine Structural Engineer: Michel Deveau, P.Eng. • Hazardous Materials Specialist: Amanda Bell, B.Sc.

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