For the first time since the dams were built, Hydro-Quebec has released information about what would happen if LG-2 burst open and the water spilled out.
Also for the first time, HQ has released a report on safety and security problems in the La Grande hydro network. Six of the 20 pages in the Hydro report are blanked out.
The problems in the report include “anomalies” in water pressure at LG-1 and LG-2. HQ engineers are at a loss to explain or fix the “anomalies.” The problem is so serious a provincial committee of engineers was created to investigate.
Also, holes are appearing in dykes throughout Hydro-Quebec’s dam network in the North, and Hydro doesn’t know why. In the last two years, HQ added on a quarter-million tonnes of rock to strengthen the dykes.
All this information and more was released to The Nation after a request under the Access to Information Act.
Probably the most interesting item we received is a large map that shows HQ’s scenario of a “catastrophic failure” at LG-2. The information on the map is not all clear, but the map does show that a tidal wave would sweep down the river and slam into Chisasibi 2 hours and 14 minutes later. Chisasibi and Fort George Island would be completely under water.
By the time the wall of water reaches the bay, it would be 20-25 kilometres wide and 11 to 13 metres high. The water would travel at nearly 50 km/h down the river.
The tidal wave would cut off the highway at around Kilometre 15 about 1h50 after the dam breaks. The highway would presumably be the only escape route for most residents.
Is there a plan for what to do if the dams fail? Until now, Chisasibi has never had anything from Hydro-Quebec to go on. Much of the information we received from Hydro-Quebec is vague and unclear. We were unable to receive any clarifications as of press time.
Hydro did a study in 1989 on what would happen if LG-2 should break, but this study was not sent to The Nation. We are filing another Access request to obtain this and other information. No study has ever been done on how a dam failure would affect Eastmain, but such a study is planned for 1998, Hydro informed us in a letter.
Hydro’s report also said the motors that open the gates of the Opinaca spillway do not work. In other words, the spillway can’t be opened if the reservoir overflows. Inadequate spillways were one of the main problems that occurred in the Saguenay floods last year. The Eastmain spillway has been opened only one time in a test in the early 1980s, as far as anyone knows.
Officials at the Grand Council of the Crees were excited about the new information released by Hydro. “There is absolutely no flow of information between the Crees and Hydro-Quebec,” said Alan Penn, an advisor to the Grand Council. “This conversation is the first time anyone has ever discussed with me any information related to the performance of the dykes.”
“What’s the assurance Hydro has the necessary control over the dams,” asked Penn. “From the point of view of Chisasibi, they have a right to know much more information than they know now.”
He said the La Grande dams should be put under independent review by a Dam Security Agency, as recommended by a panel that looked into the floods in the Saguenay.
