Once you have your site set up, you need to empty the water out of the lock so you can see what needs attention. Locks are very seldom ‘dewatered’ so you don’t know what you are going to find – water can do a lot of damage to concrete over the years if it gets into cracks and rusts the reinforcing metal bars inside.
All locks have grooves running down the walls outside the lock gates. To drain the lock, you drop metal or wooden panels into the grooves at each end to create a watertight barrier. You then pump out the water out and climb down to take a look.