Every year in Ottawa, Canada, they encounter a problem. Not the cold, but what the cold causes – ice. The Rideau river passing through the city freezes over every year. Now this may not sound like a problem but I assure you it is.
The problem is that as the ice freezes, it freezes in large sheets and cannot pass underneath the bridges and downstream, meaning that the ice builds up, and come summer it will melt and flood, putting over 900 buildings at risk. So something is done to stop this would be catastrophe.
The Rideau Valley Conservation Authority breaks up the ice, but it is no easy job with the ice over a metre thick in places. What the authority does is use truly gigantic circular saws and cuts huge swathes through the ice, cutting the frozen debris into long strips. However the strips are too long to drift down still. So they do a bit of jostling.
Specifically the type of jostling with dynamite, the best kind of jostling. The Rideau Valley Conservation Authority set down between 700 and 1500 kg of dynamite and then step back for the show. The explosions shatter the ice and break it up into small enough chunks to flow happily down stream.
They used to use 8000kg a year until 1992 when they realised that several tons of explosives isn’t very good for nearby buildings.The authority currently spends $460,000 a year on dynamite.Click here to watch the explosions in action.