WRG Works Photos:
Lichfield
Photos by Martin Ludgate, Izzy Gascgoine, Nina Whiteman, Steve Paice & Lesley McFadyen
Text by Martin Ludgate

After the relatively unskilled mass 'slash and burn' at Pant it made a change to go to Lichfield for a week of rather more technical work by a smaller team.  The job for the week was to make a short length of the canal waterproof so that it can be refilled, as a trial length for a 550 metre section - and ultimately as part of the reopening of 10km of canal to re-link the Wyrley & Essington Canal to the Coventry Canal and open-up easier access to the underused northern parts of the Birmingham Canal Navigations system. 

As the canal passes through very sandy soil here, it needs to be lined to make it watertight.  Traditionally puddled clay would have been used for lining, but for the Lichfield job a new technique was to be used, making use of a synthetic lining material consisting of a layer of 'Bentonite' - a special type of clay - sandwiched between two layers of synthetic fabric.  One of the properties of Bentonite is that it swells up to several times its volume when in contact with water.  So long as it can be kept in compression (usually by covering it with a layer of soil) this makes it 'self-healing' so that if punctured, it will swell sideways to fill the hole.

This technique has been used on several other canals; however this was the first installation by volunteers - hence the reason for installing and testing a trial length first.

The section to be re-watered begins at this new lift-bridge which been built to carry the towpath across the restored canal.
An excavator was used to unroll the Bentonite across the canal.

At the edge, it was unrolled to the end and cut off....
...the edge was sealed with puddle clay.

Soil needed to be put over the top of the Bentonite. The digger was used, as well as more traditional means.
The sections of lining needed to be joined together.  This was done by laying them with a 150mm overlap, folding back one piece (as you can see, holding it back is hard work for a team of three people!) while a layer of Bentonite powder is spread along the join, then putting the liner back into place.  Once the canal is re-watered, this powder will swell up to make a watertight seal.  As you can see, the lining material looks rather like carpet!

Near the liftbridge, concrete was placed over the Bentonite.
At the other end, a dam was built.

The off-side bank needed to be strengthened by installing a honeycomb material. Here the honeycomb is being filled with dry-mix concrete.
Hopefully we didn't leave too many volunteers buried under the Bentonite!

Back at the hall, we had a fantastic meal...
...followed by a bizarre game of Pictionary...


...and another WRG 30th birthday cake...
...provided by Jan.


In February 2001, WRG NA re-watered the section.

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