How to Remove a 15 Metre (50-Foot) Long Bolt

 Because of the massive size of much of our critical equipment, renovations or major overhauls are never simple or easy jobs. This week, for instance, we began renovating one of the spillway gates and related structures at our Whitehorse dam. Just as their name suggests, the gates allow us to release (spill) water from Schwatka Lake into the Yukon River. The East Gate was refurbished a couple of years ago. Now we are doing the same to the West Gate.

The gates operate on a screw-lift mechanism, where large gearboxes sitting at the top of a platform are turned by a central gearbox assembly. These gearboxes act on 15 metre (50 foot) long screws (bolts) that are attached to the gates to move them up or down. Each bolt weighs 5,900 kilograms (13,000 pounds), so obviously this is not a job for your average hand-held wrench!

Instead, Project Manager Darrell Johnson called in TMar and R.C. Crane to help us with the removal. The screw covers (the orange and white structures being moved in the photographs) were removed yesterday without incident. The actual screws will be removed this afternoon. The screws will be shipped to Southern Canada where they will be inspected and refurbished. We’ll re-install them next month. Also next month we’ll do some maintenance on the spillgates themselves.