canalboat.co.uk Canal Boat November 2017 43partnerships with communities, energy
groups and CRT. The other project is to
install a floating landing stage for a sailing
club based on the reservoir and used a
great deal by groups supporting
disadvantaged children.
Our second site visit is to Foulridge
Upper Reservoir, built to supplement
Foulridge Lower Reservoir, which in turn
feeds into the Leeds & Liverpool Canal
just west of Foulridge Tunnel – and it’s
quite a contrast. A much later reservoir
dating from 1866, it’s hardly been altered
since it was built, other than adding a low
concrete wall along the top of the dam in
the 1950s to deflect waves. But here, the
issues aren’t about maintenance: they’re
about coping with eventualities.
The inspection report indicates that an
extreme flood would overtop the dam,
washing away the path behind the
concrete wall and ultimately threatening
the dam itself; and that in addition, water
passing down the overflow spillway could
overflow the sides, wash out the adjacent
ground, and again damage the dam.
The work in progress involves raising
the dam crest wall by adding another half
a metre of reinforced concrete – as we
watch, a team are at work dismantling the
wooden shuttering around a section that
has recently been cast. Meanwhile the soil
alongside the overflow spillway chute is
being dug out and replaced in a way thatwill be better able to withstand a heavy
flow of water. This involves putting
concrete behind the channel side walls,
installing a geotextile membrane and
gabions (wire cages filled with stones) and
reinstating the topsoil on top.
We’ve looked at just two of CRT’s 72
reservoirs requiring regular inspection.
Work in progress elsewhere includes
grouting spillways at Slipper Hill Reservoir,
investigating leakage at Barrowford, and
investigating the state of the crest wall at
Winterburn (all on the Leeds & Liverpool).
Then there’s raising the dam at
Tardebigge and lining the cast iron
draw-off pipe at Upper Bittell (both on the
Worcester & Birmingham), adding new
siphons to increase the draw-off capacity
at Bosley on the Macclesfield and dealing
with mining subsidence at Elton on the
Manchester, Bolton & Bury – the fact thatthe canal has been abandoned doesn’t
free CRT of its responsibilities.
But if, despite all this work, the worst
came to the worst and an emergency
arose, how would CRT cope? There are
inundation maps in place for every
reservoir, showing the maximum extent of
flooding in the event of a breach, and for
those with the more serious consequences
there are emergency plans detailing which
buildings would need evacuating, and
which roads would be unusable.
To find out if the plans work, a recent
exercise was carried out by the Trust in
conjunction with the British Dam Society
(yes, there really is such an organisation).
At the start, none of the staff knew that it
was just an exercise – it began with a
phone call in the middle of the night to say
there was an emergency at Foulridge
Lower Reservoir, and it ended with them
demonstrating that it actually was
possible to get one cubic metre per second
of emergency pumping capacity set up to
deal with it by the end of the same day.
So there are grounds to be reassured
that even if, despite the inspections,
reports, and recommendations, the worst
were to occur, the situation could be
handled with a rather less desperate
response than one man and his spade.
And let’s hope that with wavering water
levels on some canals this summer there
will be plenty in store for next year.Foulridge Upper Reservoir: rebuilding the spillway channel sides
Raising the Foulridge dam crest wallRESERVOIRS
CB