The recent emergency at Toddbrook has tended to overshadow an earlier
incident at Combs Reservoir when the dam wall was damaged during a storm and threatened to cause flooding.
Combs Reservoir in 2015. The dam is on the left.
The dam at Combs
Reservoir had been repaired on a number of previous occasions
including the removal of trees in 1948 and the stemming of a leak in
1969 caused by decayed roots. It had been constructed in 1805 to the
design of Benjamin Outram and raised by 2 metres in 1820.
A severe storm hit
Britain on 3rd January 1976. Winds reached an average speed of 70
knots, gusting in places to 87 knots and causing widespread flooding
and damage, especially in Eastern England. It was even stronger in
Northern Europe where it reached hurricane force.
Another storm
followed on 29th January bringing strong winds and very cold
temperatures.
On the morning of
29th January, during the storm, a 10 metre wide slip occurred on the
downstream slope of the dam. The damage was discovered at 7.15,
reportedly by a postman on his rounds and the police and British
Waterways alerted. At 9.0am the draw off valve was opened to lower
the water level which was 11 cm above the spillway level and only
90cm below the level of the wave wall. Temperature was below
freezing and spray was blowing over the crest. A deep cut was made
in the overflow weir and pumps used to lower the water level to
eighteen feet below the weir level and a month later by a further two
feet and eventually twenty four feet.
Investigations
followed and these involved digging a number of trial pits and
drilling many bore holes to take soil samples. Eighteen months later,
little progress had been made and it was questioned whether there was
an economic case for repairs to the dam. It was 1978 before British
Waterways were able to assign an engineer to the project and his
proposals included strengthening the downstream face of the dam and
installing a wave wall along the top. The road at the foot of the dam
would be rebuilt at a higher level and the space infilled. .
Although design work progressed it was not until 1982 that a capital
grant was received to finance the project. Work commenced in June. It
was December 1983 when the work was completed and the water level
restored.
It was concluded
that cavities had been created at the base of the wave wall by wave
action leading to saturation by spray of the downstream face. An
investigation found that the dam had been marginally stable for a
long time and that the height of the wave wall was inadequate.
Several people can
recall events of the day. The team working on the dam
had to crawl along the ice covered surface to assemble piping to
syphon water using pumps. These operated for many months before the
new splash wall was installed. A worker had to climb down to open
the sluice at the far end of the dam and returned with the back of
his donkey jacket iced up and his hair appearing as icicles. A small
card box was found at the bottom of the drained reservoir. It was
full of live .38 pistol bullets.
Although the dam was not breached a massive amount of water was released during the emergency. There are many
reports of flooding and some people were evacuated especially between
Combs Reservoir and Horwich End.
At Cadster Farm
three fields of hay were ready for bailing and were lost to flooding;
a hay rake was never seen again. A bailer jammed under Cadster Bridge
and the river was 3 feet deep and the width of the field.
An area at the
bottom of Elnor Lane where houses have since been built was flooded.
We are grateful to
Wendy Alsop for allowing us to reproduce photographs taken by her
late husband, Derek.
Many of the details
of the slip and its repair are reproduced with permission from the
history of Combs Sailing Club. The Club maintained their activities
throughout this period despite greatly reduced water levels. They
received much assistance from Toddbrook Sailing Club.
Damage
to the banking - January 1976 Reducing
the water levels January and February 1976
Installing
a new wave wall on the dam – July and November 1983
Building the new roadway 1983