25th November 2012
Today was the long awaited Stret Lock Open Day; the chance to go inside a lock and view the works up close.
Stret Lock was restored in the 1990s. However for very many years some boats had got stuck. These boats might have been slightly wider or deeper than normal. There had been lots of theories about the problem, some even suggesting that the lock was banana-shaped. This was somewhat ironic because Stret Lock is thought to be a corruption of Straight Lock.
The general consensus was that, in the 240 years since the lock was built, the ground pressure had forced the walls inwards.
British Waterways undertook a major inspection in 2011. Infra-red photographs were taken. These were used to create a computer simulation of the lock. A virtual boat was then introduced so that any problem areas were highlighted. The lock was indeed found to be narrower than it should have been.
The lock widening scheme involved taking down two of the of the outer brick courses on the towpath side and replacing them with one course, increasing the width by 50mm. This was not taken down fully to the lock floor but extended beyond the minimum depth dimension for the canal.
This was a part of the Canal & River Trust’s poster at the entrance.
Upon arrival everyone did a short survey and was equipped with a hard hat.
There was then a safety briefing.
The water was kept out of the lock by means of stop planks which fitted into special slots just above the lock gates. A bit of water still came through, so there was constant pumping to clear it.
Then one got the first proper view.
The wooden pieces are the remains of the original ground anchors. The bricks were laid 240 years ago. The stub on the bottom right is where a new ground anchor has been driven 2 metres into the bank to hold the wall back.
Anchors have also been driven into the off bank wall.
Having stripped away two layers of bricks, a single layer is being replaced. The new bricks are bound to the originals with wall ties. The stone course is the original stone. The gap behind will be filled by concrete.
This is what it is all about. The vital couple of inches that will allow all craft to get through in the future.
On the way out, one could see the coping stones that had been lifted from the lock side.
The Chesterfield Canal Trust would like to thank May Gurney for sponsoring the Open Day, the Lock Keeper pub for allowing us to park our publicity trailer in their car park and especially the Canal and River Trust for doing the work.