Whaley Bridge dam could be 'fully broken' within hours and cause 'massive flooding', says expert

Katy Clifton1 August 2019

A dam which has seen an entire town in Derbyshire evacuated today over fears it might collapse could become “fully broken” within hours and cause “massive flooding”, an expert has said.

Residents in Whaley Bridge were told to leave their homes due to fears water from the Toddbrook Reservoir could swamp their homes after a dam was damaged in flash floods.

An expert from Brunel University in London has now said the damaged spillway of the dam – which contains an estimated 300 million gallons of water – could become “fully broken” within hours.

This could lead to “massive flooding” following the heavy rainfall, and the estimated 1.3m tonnes of water inside the dam is at risk of wiping out the small town if it was to collapse.

Sandbags are laid at Toddbrook Reservoir
PA

Dr Mohammed Heidarzadeh, assistant professor and head of coastal engineering and resilience LAB, said: "Due to heavy rainfall in Whaley Bridge area, the spillway is now broken and a big chunk of its concrete structure is damaged.

"There is a possibility that the spillway could then become fully broken in a few hours. If the spillway is fully gone, the embankment dam will be washed away very rapidly, which could cause a massive flood."

He added that a similar situation occurred at the Orovill dam in California in February 2017.

However, as long as the core of the reservoir is not damaged, the wall "should be okay", according to another specialist.

"Within the last few years new valves have been placed in the dam to expedite rapid drawdown in emergencies: presumably, this is happening now," said Professor Roderick Smith, from Imperial College London.

The former chief scientific adviser for the Department for Transport said the reservoir previously had "issues" with an inadequate valve system which has seen been replaced.

Severe flooding in South Yorkshire in 2007 sparked the evacuation of roughly 700 people around Ulley Reservoir, near Rotherham, over fears its walls could burst due to unprecedented rain and apparent "areas of weakness".

Police have told the 6,500 residents of the picturesque market town to bring pets and enough medication to last for 'a number of days.'

They have been urged to head to a local school due to "an unprecedented, fast-moving, emergency situation" caused by heavy downpours.

Whaley Bridge dam - In pictures

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Toddbrook Reservoir - which contains around 1.3 million tonnes of water - has seen "extensive" damage during the flooding.

Images appear to show a huge hole in the dam wall.

Firefighters deployed from across the country are using at least 10 high volume pumps to reduce water.

Late on Thursday, an RAF Chinook was also drafted in to help prevent the dam from collapsing further.

Derbyshire Police said more than 400 tonnes of aggregate will be used to divert water from entering the reservoir.

Police are pictured arriving to evacuate people from their homes in Whaley Bridge
PA

Deputy Chief Constable Rachel Swann, chairwoman of the Local Resilience Forum, said: "To move the substantial amount of aggregate into place - a Chinook helicopter will be operating in the area in the coming hours to allow precise placement and divert the flow of the water.

"With all that said, at this time the future of the dam wall remains in the balance and I would remind people of the very real danger posed to them should the wall collapse."

Water pumps will continue to remove water from the reservoir to relieve pressure on the dam wall.

At around 9.30pm, further evacuations took place downstream of the reservoir as work continued to ensure the structure of the damaged wall.

A small number of properties in Furness Vale and New Mills - outside Whaley Bridge but inside the flood risk area - were evacuated.

Local resident Ash Cox said police officers told him evacuation was "mandatory" and that people could be arrested if they chose not to leave.

"We were told by the police officer leaving was mandatory... and if we don't leave, he would have to make arrests," he said.

There are fears the town of Whaley Bridge could be swamped by water from the Toddbrook reservoir
PA

"That would be very sad to do so we decided to follow procedure and leave even though we are well above the danger zone in our eyes."

Urging people to leave their homes, police wrote on Twitter on Thursday: "Whaley Bridge is being evacuated due to the ongoing situation at Toddbrook Reservoir.

"If you are being evacuated then please start heading to #Chapel High School, Long Lane, #ChapelEnLeFrith, #HighPeak, SK23 0TQ, where further direction will be given.

"Officers and staff will be at the school to give further direction but at this time we aren't sure how long the evacuation will take.

A roadblock is put in place at Whaley Lane the entrance to the village of Whaley Bridge
PA

"Please make alternate arrangements to stay with friends/family, ensure that pets and medication that may be needed for a number of days are taken."

It came after heavy downpours brought flooding and scenes of "complete chaos" to parts of the UK.

Flooding due to sustained rain disrupted all lines on the railway between Manchester Airport and Wilmslow early on Thursday, according to train operator Northern.

A major incident was declared late on Wednesday in Poynton, Cheshire, due to "severe flooding" and local groundwork landscaper Adam Wainwright described the aftermath as "complete chaos".

He said: "We had flash flooding and heavy rain.

"There have been houses where the flood has had an effect, and it has just ripped through the houses. The water has just gone through the front door and out the back."

A resident of the village of Whaley Bridge
PA

A bridge which partially collapsed due to the flooding in Poynton caused a nearby tree to fall into Simon Howcroft's garden, where a sinkhole also opened up.

Cheshire Fire and Rescue Service (CFRS) said firefighters, emergency services personnel and staff from Highways England were helping those affected, with a rest centre established at Poynton Civic Hall.

CFRS added: "Please bear with us, crews and police officers are working very hard to get to those in need and the most vulnerable in our communities."

Police urged people not to ignore "road closed" signs by driving or walking through water.

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