A new underwater robot designed to carry out important reservoir maintenance tasks could produce huge savings of time, money, and labour, the New Civil Engineer reports. The robot, known as Valiant, is currently being trialled by the Canal & River Trust on Carr Mill Reservoir near St Helens in Merseyside.

The tracked and remotely operated vehicle allows engineers and contractors to carry out maintenance tasks without draining the reservoir. This will save hundreds of thousands of pounds in fish rescue fees, and means that the existing water levels can continue to be used for water sports and angling activities.

Canal & River Trust project designer Tim Brownrigg said: “The Valiant was developed in collaboration with diving contractor Edwards Diving Services and is set to revolutionise how we manage underwater reservoir maintenance, particularly difficult jobs like replacing old, worn-out valves in locations where it is too dangerous to send divers.”

“The trust cares for 72 reservoirs across its 3,200km canal network so the potential reduction in disruption for local residents, water sport enthusiasts and wildlife is immense and of course, cost savings are likely to be significant,” Brownrigg added.

The Canal & River Trust have undertaken a major repair project to upgrade Carr Mill reservoir, which began in 2020 and is due to be completed in July. It is the biggest inland body of water in Merseyside, situated in beautiful countryside between Manchester and Liverpool.

Carr Hill is in the Blackbrook valley and is popular with locals and tourists alike. It is enjoyed by walkers, wildlife enthusiasts, anglers, and boaters. It was originally a mill pond powering Carr’s Corn Mill, and was expanded on a massive scale during the 1750s to provide water for the Sankey Canal, which was the first English canal of the industrial age.

The reservoir also provided power for the industrial mills of the Gerrard Estate, such as the Carr Corn Mill. It was important in the early industrial development of using water power to process iron. During the 1960s, the site was successfully redeveloped into an Entertainment Park, and now attracts thousands of visitors every year.

The £2m upgrade scheme was delivered in two phases, and thanks to the innovative underwater robot, water levels had to be lowered only slightly below the usual level.

The first phase of the work was carried out at the dam wall by the railway viaduct. It involved the removal of an asbestos concrete pipe and the installation of a new gauging weir, plus a security grill, safety railings, ladders, steps, joint sealant, and other safety and access enhancements.

During phase two, two existing underwater valves in the dam embankment next to the A571 Carr Mill Road were replaced with four new ones, complete with supporting networks. The original valves dated back to the 1860s and were in poor condition.

One of the original valves will be displayed within the Entertainment Park as a monument to the ingenuity of the Victorian engineers who built the reservoir and canal system.

A range of improvements and repairs were also made to increase the resilience of the crest road embankment and repairs to the valve hut building. Extensive repairs were also carried out on the old spillway and its bridge was strengthened to enable it to withstand modern traffic loads.

Meanwhile, the Canal & River Trust’s plans for the permanent repair of the Toddbrook Reservoir Dam, which partially collapsed in the summer of 2019, have been put forward for a second public consultation.

Daniel Greenhalgh, Canal & River Trust North West Director, said: “More than 300 people submitted feedback at our first public consultation last September and this played a significant role in helping to shape the chosen repair plan we now put forward. We would love to hear from people, either online or in person with their feedback.”

The final plan involves a new side channel weir, a tumble bay, a spillway channel, and stilling basin being built on the northern side of the dam. The Trust have said the repair project will cost up to £16m, which they will fund themselves.

The reservoir, which formerly supplied water to the Peak Forest and Macclesfield canals, has been disused since the incident in 2019, which led to Whaley Bridge residents being evacuated from their homes as it was feared the dam could burst and flood the town. The damaged spillway has been made safe ahead of the planned new construction works.

If planning permission is granted for the new weir and stilling basin, they will connect with the River Goyt via a channel through the park, and the old slipway will be decommissioned and grassed over.

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