Rubber Duckbill Valves: Never get stuck in the mud

Stormwater discharges to the tidal section of the Parrett River at Bridgwater were constantly blocked due to mud & silt with the metal flap valves unable to cope.

In 2013 Wessex Water decided that rubber check valves from Mesaurit would provide the solution, with their proven track record in being free draining and self-clearing. We have no doubt they will be happy with their choice for decades to come.

1200mm and 1000mm GuvNu wall mounted duckbill valves were bolted to concrete headwalls on riverbank

Bridgwater and its surroundings have a history of flooding, with the unfortunate overflow of combined systems in larger rainfall events. The area of Bridgwater to the east of the river is designated as Flood Zone 3a in the Sedgemoor District Council Level 1 SFRA, which means it has a high probability of fluvial and tidal flooding. Much work has been done over recent years in consultation with the EA to remedy this situation, including the construction of several stormwater tanks in 2005. The largest of these tanks (2350 m3) is connected to the Taunton Road Pumping Station (rated at 700 l/s) which discharges to the Parrett River on the west bank between two bridges in the middle of Bridgwater. Water levels in the river are determined by the tidal variation within the Bristol Channel at the mouth of the river, which has one of the greatest tidal ranges in the world. The tidal influence extends approximately 10km upstream from Bridgwater.

Despite dredging and de-silting work carried out on the river, the volume of mud & silt in the river continues to be an issue for outfalls on its banks. The two outfalls in this project needed to be cleared of mud before work could commence on replacing the non-functioning valves. Further evidence of how difficult any maintenance work can be here! Properly designed rubber duckbill valves are the only valves proven to maintain function when covered in mud and other debris. In an area prone to flooding, it is more important than ever that every part of the drainage system functions as intended in the long term.

Metal flap valve being removed from the gravity outfall. It was unable to open when buried under the mud and therefore unable to drain the upstream system.

1000mm GuvNu wall mounted duckbill valve installed on the surface water outfall gravity discharge pipe, being lifted into place on to the headwall.

1200mm GuvNu wall mounted duckbill valve on the outfall of the stormwater pump station being lifted into place. Note the lifting hook on the valve bill - standard on all valves >450mm.

These guys had to be hosed down with a powerwasher after this installation!

The valve handles both silt build up and back pressure from high water level.

The GuvNu duckbill valve mounting is custom made to fit the site structure and opening.

As the line pressure builds up in the upstream system, the valve opens and discharges flow even when submerged, the exit flow velocity flushes away the silt build up in front of the valve, offering a self clearing solution. the rubber duckbill valve is more than able to handle both the silt build up and backpressure during high water level events in the river.

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