SURPRISE DISCOVERY of original structure
Avon Navigation Trust engineers uncovered a nasty surprise but also a rich slice of history when they plunged into major work at Evesham, their third complete lock refurbishment in as many years.
The scheduled dewater, repair and upgrade project hit a serious snag when the ANT team’s usual in-depth survey revealed that crumbling 380-year-old stonework behind the lock meant the wall was in danger of collapse.
However deeper investigation also unveiled the actual historic lock structure, built by Fladbury engineer William Sandys back in the 17th century.
“It was a fascinating discovery and, we believe, a first for the Avon,” says the Trust’s Chief Executive Clive Matthews, who led the ANT team.
“We know that some of the locks, and most of the mills, were built on top of a raft of elm beams, probably taken from sailing ships.
“But Evesham’s is constructed from U sections of beams every ten feet and we only discovered there were uprights when we were trying to work out why the walls had lines of damp.”
The ANT team has a rolling maintenance programme and has perfected its methods for major work on the 17 locks on the 22 mile navigation.
Once engineers had drained the 535 gallons of water, they were able to work unhindered to repair the wall and two leaking cills.
Other improvements included adding new handrails and future-proofing the lock with modern engineering solutions, leaving it all well and good for the next 30 or 40 years.
The team took the opportunity to add a conduit under the dry lock to deliver power and water to the Evesham lock island moorings for the first time.
Clive is also trialling an ANT innovation at Evesham to foil an inherited problem on some of the historic locks.
The Top Paddle Deflector will divert the plume of water that shoots out when the paddles are raised.
What lay beneath: historic elm beams used to build the lock when William Sandys was authorised to make the Avon navigable from Tewkesbury to Stratford-upon-Avon, with King Charles I’s Letters Patent in 1635.