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Emergency at Whaley Bridge 

Potential disaster was narrowly averted in possibly the darkest hour for the Canal & River Trust in its seven-year history

A deluge of rain fell on the Peak District on the night of 31st July, and some observers felt like half of it had descended on Toddbrook Reservoir, overlooking Whaley Bridge at the head of the Upper Peak Forest Canal. 

By the following day the water began overtopping the spill weir, and suddenly a section of the concrete gave way, with water eating away at the soil underneath. 

Fearful of a collapse, the police called for an immediate evacuation of a quarter of the town’s 6,500 population.

To prevent disaster, dam pumps were soon installed to lower the water level and RAF Chinook helicopters dropped hundreds of aggregate-filled bags to stabilise the structure. 

An additional worry was that if the dam had collapsed the torrent of water could have swept away the modest 35ft aqueduct that carries the canal over the River Goyt. Twenty-three miles of the Upper Peak Forest and Macclesfield canals, which effectively hold more water than Toddbrook itself, would then also empty back into the River Goyt, compounding any disaster. Stop planks were inserted along the canal near New Mills to forestall this.

The reservoir slowly began to lower and worries eased. But it was six days before residents were allowed to return to the affected area, while rail services through the town were halted for the duration.

Analysis 

Toddbrook, a canal reservoir completed in 1839, takes water from the Todd Brook, a tributary of the River Goyt. Water only goes into the reservoir during high flows in the brook; this was done to ensure mill owners on the River Goyt always had a water supply. Since the emergency, this inlet has been blocked so that all the water now flows around the reservoir into the bypass channel.

Originally the reservoir keeper lived on site. He would watch the weather and reduce the level when heavy rain was predicted. Now monitoring is through an electronic SCADA system, and the reservoir inspected twice a week, a requirement under the Reservoirs Act. 

The current spill weir was built in the late 1960s after a flood risk analysis decided that the original structure was inadequate. It is 83 yards long and nearly a foot higher than the 1839 weir, and at the time was doing exactly what it was designed for.

Engineers said the amount of water flowing over the weir at the end of July was nowhere close to the maximum predicted for the design, so the subsequent failure of the concrete capping slabs gives cause for concern. 

The UK’s 1975 Reservoirs Act is claimed to have the most stringent inspection protocols in the world, amended further by the Flood & Water Management Act 2010. Toddbrook had a mandatory ten-year inspection in November 2018 and had been given a clean bill of health.

Initial works include a temporary repair to the spill weir and pressure grouting of the top capping. The next stage is a detailed investigation into the structure to decide on the necessary repair works, which are likely to be lengthy and expensive. 

Eleven 12in submersible electric pumps are still in place, with over half a mile of piping. They are supported by a floating platform to stop them becoming clogged with silt. These will be used to keep the water level low until the repair works are finished. 

A fish rescue took place once the water level fell below emergency levels, with around 30,000 transferred to Bittell Reservoir, south of Birmingham, which itself had been drained and repaired in 2018.

Meanwhile, for boaters, water levels in the long 23-mile pound from Whaley Bridge to Bosley are not in immediate danger; there are three other canal reservoirs (Combs, Bosley and Sutton) feeding this summit length. 

Businesses affected  

One business caught up in the emergency was the Judith Mary trip-boat, which has operated from Whaley Bridge since 1983. Owner Suzy Kelsall said they were carrying 40 people on a cream-tea cruise when friends phoned to tell them to get off the boat as soon as possible, something not easily accomplished for the (mainly elderly) passengers.  

“We felt we were in the middle of a huge disaster movie film set,” Suzy Kelsall told WW. “There were evacuees, roads closed, that Chinook flying overhead, emergency services everywhere, volunteers and our fantastic community offering shelter, beds and food to one another along with neighbouring communities. 

“After six days of being out of our homes I have never enjoyed putting my key in the lock in my front door and walking in so much. The next day we were able to collect the Judith Mary, and the one-hour journey back was incredibly emotional.” 

FAB day 

The Whaley Bridge Canal Group, a community interest company set up earlier this year to restore the transhipment warehouse, said it would be holding a special FAB (Food & Art at the Basin) market on 7th September and asked boaters to return to the town. 

Rupert Smedley 





Thursday 15 August  | Andrew Denny  | 2.32pm, Thursday 15 August 2019

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