So, if Nalcor doesn’t build a whole new dam at Muskrat Falls (at whatever astronomical cost) it looks like the so-called North Spur (a long bank of “dangerous” clay that must otherwise hold back the entire load of the reservoir) could collapse any time after the valley is flooded — sending a wall of water to threaten anyone living downstream.
Actually, the problem is even bigger than that, since the unstable glacial deposits are everywhere and have a long documented history of collapse, making the entire lower stretch of the Churchill River unsuitable for dams and reservoirs — and that’s even before the earthquakes start.
So, let’s start with the earthquakes: both kinds (natural and reservoir-induced) are exactly what’s needed to turn from solid to liquid the 110-metre deep bank of glacio-marine clay that makes up the North Spur formation. Natural earthquakes are rare in Labrador, but hardly unknown — in fact, one occurred only 150 kilometres south of Muskrat Falls in 2012. According to Natural Resources Canada (by way of and with thanks to Cabot Martin), dams at Muskrat Falls and Gull Island will increase the number of earthquakes in the region because the nearly inevitable earth tremors caused by the massive weight of the new reservoirs could reactivate the whole Melville Rift System, a major but hitherto dormant earthquake faultline that runs past Muskrat Falls all the way from Groswater Bay to the St. Lawrence Lowlands.
Nalcor says it has found “no evidence of seismic activity” in recent geological times, but the company’s construction project is bound to change that, making already commonplace landslides even more likely. Nalcor, however, is not worried, explaining to its own satisfaction that the dams will be built on hard rock — neglecting to mention that the North Spur clay sits on wet sand. Despite this, the company says it has everything under control, including the price.
“The capital cost estimate for Muskrat Falls includes the work identified in the 1999 study relating to the North Spur stabilization,” the company said in a 2012 technical note.
The Jacques Whitford geotechnical study (which, like an increasing number of pertinent documents, seems not to be publicly available) recognized the clay problem and suggested a few things that could be done to shore up the spur. However, Jacques Whitford strongly recommended that more research be undertaken. Nalcor promised to do it in 2012, but apparently nothing happened. Now Nalcor is promising it for this year and it might take place because (as Cabot Martin points out) Nalcor has gotten its close friends at SNC Lavalin (who, to their credit, point out that Nalcor ignores “the probability of reservoir-induced seismicity”) to launch the North Spur stabilization project — price to be announced later. That’s how news of a third dam has come out. The senior engineer needed to head up the project has to know all about building “deep cut-off walls” — a dam by any other name. Such a structure would be a major undertaking — possibly almost as large as the other two Muskrat dams combined, requiring the excavation and removal of all the dangerous clay, tons and tons of it.
Remarkably, even a third dam to replace the North Spur won’t solve all the problems posed by landslides. A third dam would remove the North Spur but it would do nothing to stabilize the big clay hill situated just to the north — a hill that by the look of it could collapse into the basin beside the dam, or onto the dam itself.
Unfortunately, there’s no sign the Newfoundland government is taking this threat to the lives of its citizens and to the wallets of its taxpayers very seriously — at least not seriously enough to finally listen to the well-founded and growing opposition to this wasteful and harmful megaproject. Sadly, the government might be happy that the project could cost double or more the current estimate — all that many more billions of dollars to dole out to the dam builders. It won’t matter to them what happens after construction, whether the project makes any money or whether the spur collapses, because they’ll have already handed out all the money.
Michael Johansen is a writer
living in Labrador.