GROUND investigations have revealed that “significant work” is needed at Cannop Ponds if the reservoirs are to remain in place, Forestry England (FE) says.

FE has today (8 December) released the results of a recent investigation which included drilling into the dams to take samples for testing.

The work, carried out by Gloucestershire company Geotechnical Engineering Ltd and analysed by engineering firm Arup, has confirmed that the dams do not contain watertight clay - as found in modern dams - and rely on the earth forming the dams to be watertight.

Within that earth, layers of granular material were found, including sand and gravel. 

FE says this type of material is permeable and explains the historic seepage and safety issues at the dams.

A statement added: “Over time, seepage through the dams will increase the risk of a potential failure. 

“If the reservoirs are to remain in place for the future then significant works are required to ensure their continued safety.” 

It comes in the same week that FE closed the site due to concerns about rising water levels in the ponds following heavy rainfall, which was labelled “scaremongering” by some who suggested FE was exaggerating the situation to back up claims that significant change is needed at the site because of the risk of flooding.

Josh Howe, Director of Engineering for Forestry England said: “This study confirms that doing nothing is not an option and that substantial work will be needed to protect properties downstream from flooding and keep the Ponds.

“We fully understand the importance of the Ponds to the local community and as custodians of the site our aim is to find the best solution to future-proof this cherished local landmark.”

The ground investigation report is the final piece of evidence for a business case to go to Forestry England’s investment committee, which will make recommendations, identify risks and outline initial estimates of the costs. 

The investment committee’s review will be presented to Forestry England’s Executive Board in early 2024, then the option to be developed will be shared with the public.

See the ground investigation report online here.