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G.M. Shrum Generating Station a big piece of B.C.'s energy puzzle

Aerial view of Williston Reservoir at WAC Bennet Dam
There are 74 trillion litres of water behind W.A.C. Bennett Dam, used to generate power that’s needed by homes and businesses across B.C.

It's the biggest generating facility in the province, and the most important

If you've never seen the W.A.C. Bennett Dam or the Gordon M. Shrum Generating Station (GMS) up close, it's hard to picture how big they truly are.

So when Bob Gammer is asked to talk about the importance of the facility in B.C.'s energy system, he first paints a picture of the sheer enormity of the dam.

"At 183 metres tall, the dam is taller than both the Great Pyramid of Giza and the Taj Mahal," says Gammer, BC Hydro's community relations manager for northern B.C. "It holds back 74 trillion litres of water in Williston Reservoir, the largest reservoir in B.C., and the seventh-largest in the world by volume."

Below the dam, water is released into Dinosaur Reservoir to be reused at the Peace Canyon Dam, 23 kilometres (14 miles) downstream. Together these dams can generate on average 17,200 gigawatt hours of power per year, enough to power more than 1.5 million B.C. homes.

And G.M. Shrum generating station is big too. The powerhouse is 271 metres (889 feet) long, 47 metres (154 feet) high and 20 metres (66 feet) wide. That's as long as two Canadian football fields and as wide as a four-lane road.

And how does Gammer help us understand the vital role these facilities play in powering our homes and businesses? With a simple fact: Every BC Hydro customer uses electricity that comes from the G.M. Shrum Generating Station.

Powerhouse and dam undergoing updates

"There's nothing else like it," says Gammer. "There are lots of other dams and generating stations in the province, of course, but this is the biggest one we have."

Keeping GMS operational at all times is critical to maintaining provincial power reliability. That's the thinking behind continual maintenance programs that aim to keep dam and generating station equipment in good working order. Staff work year-round to maintain the day-to-day reliability, but as with all facilities, the time comes when regular maintenance just isn't enough.

"GMS is more than 40 years old and large parts are starting to wear out and need replacement," says Gammer. One way to think of it, he says, is to think of maintenance on your home. Good maintenance like repairing cracks, cleaning gutters and updating appliances is necessary all the time, but eventually, he says, you're going to need to do major repairs, such as replacing your roof. "And we did that very thing at Peace Canyon."

There's a lengthy and complex capital program underway at GMS and W.A.C. Bennett to complete these major repairs. Along with maintaining the critical reliability, these heritage facilities are benefiting from the improved technology and equipment available today.

Just like you'll get more out of a laptop manufactured today compared to a computer manufactured in the 1980's, new equipment such as transformers and turbines perform more efficiently today compared to those installed when GMS first went into service.

  • Replacing transformers at GMS. Transformers increase the voltage at the station to 500,000 volts to efficiently carry electricity over long distances, and 12 of the 30 transformers at GMS have been replaced over the last five years.
  • Replacing five turbine runners at GMS. Through the power of falling water, the turbines rotate at 150 rpm, spinning the connected equipment in the generator to produce electricity. This multi-year project will wrap up in 2017.
  • Upgrading the control system for the generating station. The unit controls on all 10 generating units needs to be replaced. Work is already underway on the second unit in this multi-year project.
  • Rip-rap upgrade on the outside of the dam face. Large rock (rip-rap) protects the upstream face of the WAC Bennett Dam from wave erosion. The current plan is to start rip-rap replacement in the summer of 2016, after obtaining all permits and regulatory approvals.
  • Spillway Chute Upgrade. Upgrades and repairs are required to improve the condition of sections of the spillway, which is 680 metres long and 30 metres wide.