Divers at work placing a large plastic sheet on the the upstream coffer dam at Trent-Severn Waterway National Historic Site of Canada lock 3, Glen Miller.
The coffer dams are installed to allow the lock to be drained for maintenance work on the upper and lower lock gate valves. The plastic sheets are installed on the water side (the side outside of the lock…) to prevent the flow of water between the wood and steel beams that form the coffer dams.
The coffer dams are comprised of multiple sections that are lowered in place by a crane and held in place by gravity and the pressure exerted by the water once the lock is drained. Each section has three layers – a wood beam, a steel beam, and one more wood beam. The three sections are formed and assembled to closely fit together, and are cut to the exact width and length to fit snugly into channels in the lock walls.
As interesting as this is, please consider staying home and enjoying the locks through the safety of your computer:
- This is an active construction site – please stay well back from the lock, and out of the way.
- DO NOT attempt to gain access to or walk on the floor of the lock.
- Lock station grounds are not staffed during the non-navigation season from mid October to the end of May and are not intended for public use during those times. As some locations are remote and isolated, an injured person could remain unattended.
- Some public safety hazards may exist. For instance, wet leaves, ice, and snow may remain on stairs and walkways.
- For public safety, it is important that people stay away from all dams, water control structures, lock chambers and lock gates.
- Visit at your own risk.
All images © 2012 CKB