A major element of the multi-million dollar Ruskin Dam and powerhouse upgrade has been completed.
For the right abutment, the most complex part of the project, BC Hydro installed the rock-fill protection wall and first row of the jet grout columns, which are key components of the specially designed cutoff wall.
This wall will control and manage seepage during, and after, a major seismic event.
This is just part of a project that's been eight decades in the making.
The powerhouse and dam were built in the 1930s and BC Hydro has concerns about how the dam would hold up in the event of a major earthquake. Both are undergoing a major facelift.
Their main purpose is to generate power to Lower Mainland electrical users, project manager Boyd Mason said.
Over the past few years, BC Hydro has taken steps to improve dam safety, including lowering of the reservoir level in 2005, the anchoring of the crest block in 2007, and improvements to the right bank in 2010.
The goal of this ongoing upgrade project, which once completed will cost between $718 and $857 million, is to improve seismic safety and the reliability of the facility.
Work is expected to be completed by 2018.
"The reliability of the generating units has deteriorated over the years to the point where we no longer had the comfort we could run those units reliably," Mason said.
Because the water that travels through the powerhouse feeds the Stave River, BC Hydro "needed to make sure that the reliability of those units was sufficient to maintaining continuity of flow," Mason explained.
Mason said knowledge about earthquakes and seismic upgrades has improved vastly since the '30s.
"We had the opportunity to take advantage of the investment we'd be doing on the powerhouse, as well as upgrade on the existing structure of the top of the dam, and improve the right abutment to withstand a one-in-10,000 [year] earthquake," he added.
One aspect of the project includes removing the seven existing concrete piers and spillway gates and replacing them with five new ones.
Once work on the spillway gates is completed, the road atop the dam, currently a single lane, will be replaced with a twolane deck and pedestrian walkway.
And starting in 2014, each of the powerhouse's three generators will be replaced, one at a time.
Much of the powerhouse equipment was installed in the 1930s, with a third generator being added in the 1950s. According to BC Hydro, much of the equipment is becoming increasingly unreliable and will be replaced with new modern units.
Each turbine and generator will take about a year to replace.
All the while, the powerhouse will continue to operate. Mason compares this aspect of the project to fixing your car while it's still running.
According to BC Hydro, this will help minimize the requirement for spills while helping to maintain continuity downstream for fish. The penstocks and intake tunnels that move water from the reservoir to the powerhouse will also be upgraded.
The switchyard, currently located on the roof of the powerhouse, will be relocated on to the left bank behind the road and rebuilt.
Mason said the existing structures and facilities have lasted for the past 80-plus years, and these upgrades will keep them sound and running in the distant future.
"We're only improving on those structures and that equipment, so we would hope to target that it would last well past 80 years," Mason said. "Our timing is opportune. You can never predict exactly when a piece of equipment is going to reach its true end of life, so I think we've maximized the value of this asset for the ratepayers of the province."
Once the upgrade is complete, Ruskin will provide electricity for roughly 33,000 homes.
Mason said there are a number economic spinoffs. An estimated 175 people will be working on the project each year.
"That's primary and direct employment," Mason said. "Then there's second and tertiary. Those people all have to have housing, they buy gas and food."
This benefits the closest communities to the Ruskin Dam: Maple Ridge, Pitt Meadows, Mission, and Abbotsford.