FORT ST. JOHN, B.C. – It’s been just over three years since BC Hydro began construction on the Site C dam, and though in that time the project has seen two B.C. premiers and one review by the B.C. Utilities Commission, the over 3,100 workers at the most recent count are continuing to build the most expensive public infrastructure project in the province’s history.
On Wednesday, BC Hydro gave took members of the local media on a tour of the 900-hectare site south of Fort St. John which, 1,123 days after work started, looks entirely different than it did on July 27th, 2015.
BC Hydro’s Community Relations Manager for Site C, Dave Conway, explained the background on how the location of Site C originally got its name over fifty years ago, when the newly-created Crown Corporation began implementing its “Two Rivers” policy of developing hydroelectric facilities on the Peace and Columbia Rivers.
“When they did the exploration of potential hydro electric operations on the river, there were numerous locations identified,” said Conway. “Everything from the Peace Canyon Dam upstream to Finlay Forks was numbered. So, Peace Canyon is Site 1, W.A.C. Bennett [Dam] is actually Site 3A. Everything downstream of the Halfway [River] was lettered. So there were actually two sites between the Halfway and Bear Flats: Site A and Site B. There were three Site C’s. There’s a bend on the river about five kilometres upstream, that was one of the Site C’s. The other Site C was just on the upstream side of the Moberly River, and there was this site here.”
Conway explained that the reason the furthest downstream of the three Site C locations was chosen was due to the geology of the south, or right, bank of the Peace River Valley.
“This location is at the approximate elevation that the height of the dam would be, and you’ve got the ancient riverbed but you don’t have the overburden materials.”
He said that had the dam been built at either of the other locations, the current work of smoothing out and removing the overburden materials on the North Bank would also need to be done on the South Bank, significantly increasing the cost of the project.
When asked about how the dam itself will be anchored in the valley, Conway explained that engineers have plans to use the impermeable layers of shale lying underneath the riverbed material and overburden at the site.
“We’ve been on this site since the mid-70’s. The site actually is littered with hundreds and hundreds of drill holes,” said Conway, gesturing to a rusted well casing nearby. “We know this site very well, we know what rock is here. So, we’re not looking for bedrock. The dam is going to rest on shales, and the powerhouse and spillway structures are going to be anchored into the shales as well. Part of our mitigation is actually to fill the drill holes on the site.”
After delays with excavating the north bank of the Peace River Valley caused BC Hydro to push back its deadline to divert the Peace River from September 2019 to September 2020, Hydro president and COO Chris O’Riley said earlier this summer that construction on the dam is still on track to be completed by its previously-announced 2024 completion date.
Conway explained that Hydro still has another deadline to meet in the fall of 2019: completion of the dam’s substation, switchyard, and two 500,000-volt transmission lines that connect it to the Peace Canyon Dam roughly 70 kilometres away.
“The generating station and the substation are only part of it. Once you generate power, you’ve got a substation to up the voltage from what’s being generated. Power is generated usually at about 16,500 volts. We have two 138,000-volt lines that presently service the area. They come out of the W.A.C. Bennett Dam’s G.M. Shrum generating station switchyard, and they come straight through: one of the lines services Fort St. John, the other services Taylor. Once the substation is in place here, we’re going to remove one of the 138kV lines, and we’re going to put in a 500kV line and energize it. We’ll then take out the other 138kV line and put in the next 500,000-volt line and energize it.”
A photo gallery, along with a video of an interview with Dave Conway (begins at 14:30), can be found below.