FURNESS VALE HISTORY SOCIETY: When Combs was in danger of flooding

Friday 7 October 2022

When Combs was in danger of flooding

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.