Flatiron Construction is retrofitting the Ruskin Dam and Powerhouse in Mission, British Columbia, about 60 kilometers (37 miles) east of Vancouver on the Stave River for owner BC Hydro.
The biggest challenge so far has been completing the retrofit in an active facility. The existing facility will remain online during construction, which requires special safety measures and close coordination with the plant operators.
“There is a heightened awareness of electricity and hot work due to electricity,” said construction manager Randy Bowman. “It means a lot of lock-out-tag-out with the owner.”
The safety procedures add layers of protection to ensure a disabled power source isn’t accidentally turned on in areas with active work.
The powerhouse, originally built in 1930, also carries other hazards in the form of toxic materials. Crews have encountered asbestos, lead and silica during the retrofit. Crews recently completed the demolition of asbestos panels from the existing walls and are replacing the wall with cast-in-place concrete. The powerhouse retrofit, which will also include installation of a new elevator and 240-ton-capacity overhead crane, will be complete by the end of this year.
On the Ruskin Dam itself, crews are preparing to replace the existing gates, piers and road deck over a period of two and a half years. The work will happen in three stages as crews move across the dam. The new dam will have five gates, replacing the existing seven.
So far, Flatiron has installed a tower crane base on the right abutment with crane erection to follow. Crews have also assembled a Terex 275 crawler crane on a 19 flexi-float barge in the lake behind the dam in preparation for the dam work ahead. In June, crews began assembling the temporary works bulkhead, a system that will fit against the back of the dam to hold back the lake and allow demolition of the piers. Demolition work began in mid-July.
Currently the lake is drained to approximately 11 meters below normal levels to allow for installation of the bulkhead. Water levels will rise again in August after installation is complete.
There are about 30 Flatiron personnel on site, plus four major subcontractors. At the height of each of the three construction phases, Randy estimates the team will grow to about 50. Work for the first phase will peak this fall.
Randy, who previously worked on Flatiron bridge projects in California, North Carolina and British Columbia, said that while working on a dam project is different, it’s not completely new.
“It’s pretty much the same as anywhere else,” he said. “The biggest difference is understanding all the operating rules in a live power plant.”
Upon completion, the facility will provide power to 33,000 homes and will be able to withstand a 10,000-year earthquake.