Aquatic Control Engineering

01777 249080

ACE installs UKs biggest WaStop Check Valve in Poole

The area around Poole harbour is well known as a tourist hot spot attracting over 3 million visitors a year.  Its shallow waters attract water sport lovers and wild life in equal measure. These shallow waters can also pose problems for flood defence.

In 2013 the Environment Agency laid out a proactive approach to minimalizing the risks presented by climate change and raise sea levels. This led to a review of the procedures and assets presently in operation in the area.  It was found that some of the sites around the harbour where not operational. There were 2 main issues that the assets encountered.  Historically steel flap valves had been installed to prevent back flow as this was the only option available at the time of construction. One of the issues with steel flap valves is the head required to allow discharge. The second issue found at various sites was caused by a natural build-up of rocks sand silt around the base of the valves. This blockage increasingly hampered the operation of the valve. Fortunately the WaStop non-return valve is designed to overcome these problems. ACE worked with Poole Borough Council and Wessex Water to supply and install a series of WaStops for strategically import sites.

One problem area that was identified was an outfall near Sterte. This had previously used a steel 1.5m flap valve. This large outfall had a comparably small head pressure causing water to back the culvert. The decision was taken to fit a 1.5m Wastop with a custom flange plate to form a tight seat to the existing civil structure. The 1.5m valve supplied for this site is the largest WaStop check valve to be installed in the UK and one of the largest to be installed in the world.

The 1.5m WaStop gets lifted into place

The size of the large WaStop meant that the engineers rethinking the installation method. Most valves previously could be lifted into place and then manually manoeuvred and bolted. In this case a combination of the size of the valve and the flange made this impossible. The installation was made even more complicated by the small operating window afforded to the team by the tide times. This gave the team around 3hrs to get the valve in place and secured before the entire site would be underneath 1.5m of water. The Installation engineers quickly decided that hiab lift beam would allow the valve to be lifted and safely supported while being secured into place. Due to the unique nature of the valve being mounted the hiab beam had to be designed and constructed specifically for this lift.

UKs Largest WaStop fully installed

The installation was complete with the addition of debris screen to prevent the build-up of rocks thrown up by turbulent waters. Previously when a flap valve had been installed it was impossible fit a debris screen as it would block the valve from opening. The design of the WaStop allows it to fit inside the outfall itself meaning that the debris screen does interfere with its operation.  One of the widely recognised selling points of the WaStop valve is it pulsing motion. This characteristic forms a natural flushing action clearing silt and debris from the valve and the screen so that operation is not restricted.

Over the last few years ACE has seen an increasing demand for the WaStop Check Valve as its unique design has found a home in greater and greater diversity of sites. ACE would like to thank Poole Borough Council and Wessex Water for the opportunity to work on this record setting site.