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WaStop NPS 4” Vertical Installation, Hull, UK

Hull, UK| The Environmental Agency, Hull City Council & Associated British Ports| Flood protection

The problem

In December 2013 a storm surge caused water to over top the existing flood defence along the Humber frontage and on the Albert dock causing flooding and widespread damage. Once the water had over topped the flood defences it filled the dock and was then able to run downhill and enter the surrounding industrial and residential areas. One of the biggest victims of the flooding was Smith & Nephew who have a large facility north of the dock. These premises alone suffered millions of Pounds of damage, alongside all the local shops and businesses.

The Environmental Agency, Hull City Council & Associated British Ports needed to do something to avoid this happening again in the future. The existing flood defences varied in height from 206,69" to 236,22" AoD and the tidal range in the area is around 196,85" to 236,22" in normal conditions, but storm conditions combined with lunar activity can see these being substantially higher.


WaStop® Inline Check valve

VBA Joint Venture Ltd (Volker Stevin, Boskalis Westminster & Atkins) were tasked with raising of the existing flood defence and the construction of new defences. One portion of the port includes a 17 716,54" long, 9,84" thick suspended concrete quay slab, sat on RC concrete columns and pile caps over the water. The quay slab originally had a free edge and so didn’t require drainage, once the flood defence wall was built 35,4" off the free edge rain water couldn’t drain away freely; this meant that any water that made it into the structure either from wave action or rainfall would be trapped, also potentially causing a health & safety risk to port workers.

A solution had to be found to enable it to drain away before causing damage to the slab & property also on the quay slab. To solve this issue the VBA engineering team proposed fitting a series of WaStop check valves vertically into the base of the structure. This utilised the fact that the  WaStop doesn’t rely on gravity to operate, allowing it to be fitted in any orientation. The WaStops were 316 marine grade stainless steel with an integral top grate secured with 3 screws which allowed them to bear the loads required when the structure was in regular use, & allowed ABP to be able to pull the whole valve out for maintenance. After the installation of the valves, a representative from VolkerStevin commented that the WaStops were ‘simple to install, high quality and effective’. This is a great example were by using WaStops, an elegant simple solution could be found to an otherwise very complex problem.

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Kerry Olsson

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Kerry Olsson
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