By Brett Gillis with assistance from BC Hydro
Elk Falls Provincial Park is located at the east end of John Hart Lake, near the city of Campbell River in British Columbia, Canada. The 1,807-hectare (4,465-acre) park is a tourist attraction, with close to 70,000 visitors per year, and is known for its winding trails and salmon fishing. What tourists may not expect to see along their walk through the park is BC Hydro’s generating station. Built in 1947, the current generating station will be decommissioned and a new, more efficient station will be built underground. The area will be restored for the public to enjoy.
|The new cofferdam at John Hart Dam is nearly complete, which will allow for the construction of the new water intake under the dam to the tunnel.|
In February 2014, BC Hydro hired SNC- Lavalin’s InPower BC, a special purpose vehicle, for the John Hart Generating Station Replacement Project. This work, now under way, is one of the largest infrastructure projects for the provincial electric utility since the 1980s.
“We are dismantling a power station in the middle of paradise and building a new, more efficient station underground,” said Alfred Hanna, who is Senior Vice President, Major Projects, Hydro, with SNC-Lavalin. “Once completed, the only thing people will see are two openings – one for accessing the new power station and the other for accessing the tunnels – everything else will be underground. The land will be completely restored and visitors will be able to enjoy unobstructed views of the natural surroundings.”
The completion of the new underground facility and decommissioning of the existing hydropower station will run into 2019, and the 1.8 km (1.1 miles) of land used for its three penstocks (the pipes that deliver water from the John Hart Reservoir to the generating station’s turbine units) will also be remediated and reforested, further reducing the facility’s environmental footprint.
A sustainable design
At close to 70 years old, the current station’s electrical output has been declining for years due to age and equipment operating restrictions. When it was built, it had a capacity of 126 MW from six 21-MW turbine-generator units, but today that number has diminished to 121 MW. The new station will have a capacity of 132.2 MW from three 46-MW turbine-generator units. The new turbines and generating units will be more efficient in turning the same water flow into electricity and will supply power to close to 80,000 homes in the province.
The current station’s generating units are in poor condition. Unplanned flow reductions from the hydro facility happen about once per year and can put downstream fish habitat at risk because 95% of the Campbell River flow passes through the John Hart Generating Station. When these events take place, it takes time for BC Hydro to recover downstream flows because water may need to be released from the dam, about 2 km (1.2 miles) upstream from the powerhouse. To eliminate this problem, the new underground station will have a water bypass facility placed beside it, allowing water to be diverted within seconds if one or more of the three turbines stops working.
|Two underground portals (top, left and right) lead to the powerhouse cavern, which is 93 meters long.|
The current generating station and the penstocks supplying it are also unlikely to withstand a low to moderate earthquake, an important eventuality given that the coastal area of British Columbia has thousands of earthquakes per year.
Because underground structures in rock can withstand more shaking than soils (liquefaction) near the surface, the new facility will have far better seismic withstand. It also will be better positioned for public safety and offer dependable power.
Progress to date
The British Columbia Utilities Commission gave the go-ahead for the John Hart replacement work in February 2013. BC Hydro then initiated preparatory work in spring 2013 and included road, parking lot and trail realignment. InPower BC did further investigative drilling work at the site. Construction work began in spring 2014, and the station replacement officially began after a July 2014 ceremony that featured Bill Bennett, British Columbia’s Minister of Energy and Mines.
Tunneling work began in October 2014, and for the first 18 months the project site will look more like a mining operation than a hydro project. Close to 300,000 cubic metres of rock – the equivalent of 120 Olympic-sized swimming pools – will be hauled out of the site. BC Hydro developed a benefits agreement with local First Nations that will receive the excess rock not needed for the project.
|A community event held in July 2015 attracted about 1,500 people to learn more about the project.|
As of September 2015, about 215 people were working on the construction site, with about 80% being local. An estimated 100 vendors on Vancouver Island have been used to date to supply goods and services for the project.
Construction of the 2.1-km-long (1.3-mile-long) tunnel, which will replace the three penstocks, is under way. With a diameter of 8.1 m (26.5 feet), the tunnel will run about 1,500 m (0.9 miles) from John Hart Dam to the new generating station and then another 600 m (0.4 miles), through a tailrace tunnel, to the Campbell River.
In July 2015, BC Hydro and InPower BC held a community site event to give the community a once-a-year opportunity to see the construction site and watch the project evolve through 2018. Visitors were transported to the site via bus, and construction activity was shut down so people could walk around certain areas, including part way down the two underground portal entries, and view the unique construction equipment on display. About 1,500 people participated.
“BC Hydro started this project in 2007 to deal with significant seismic, station reliability and downstream fish habitat risks,” says Stephen Watson, BC Hydro’s communications lead for the John Hart project. “It’s great to see the innovative design begin to take shape in the construction phase. BC Hydro achieves our goals, and the community is really benefitting as well through jobs. In addition, benefits to the park, including a new suspension bridge at Elk Falls that opened in May 2015, will more than double the number of park visitors. We couldn’t be happier.”
When complete, the total cost of this work at John Hart Generating Station is expected to be $1.093 billion.
Brett Gillis is a writer for SNC-Lavalin.
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