Side Hung Door Installation

Aquatic Control Engineering Ltd (ACE) have recently completed the replacement of two top hung flap valves at a coastal location in the North West of England. The replacement saw the installation of two sets of two 3m wide AQUIKO stainless steel side hung doors.

The non-return valves were located on the downstream side of a culvert that runs under a flood defence scheme. The doors allow the drains in the area to empty away to the sea during a low tide, while preventing seawater passing upstream during high tide events. The local area around Cockerham in Lancashire has a significant amount of arable farmland which would become flooded if the gates fail.

The local community were enthusiastic to see side hung doors used at the site in replacement of the existing top hung flap valves, following positive experiences at another site. The local community had seen that the side hung doors offer many benefits including being less likely to silt up and less likely to be affected by debris while still offering excellent flood protection.

The Environment Agency (EA) were also eager on the side hung door replacements as they represent the best practice laid out in their Elver and Eel Passage Guidelines. The EA Guidelines state “hinged side gates (side hung doors) provide the best option for eel passage over a range of flows and are considered to be a good Best Achievable Eel Protection (BAEP) installation choice.”

The vertical hinge orientation of side hung doors allow the gates to open far more easily, to a greater extent, and for longer. This affords fish the greatest possible opportunity to migrate through the flood defence. In 2015, Cley New Cut in Norfolk reported “a side-hinged gate was closed for 50% and 37% of the tidal cycle for spring tides and neap tides respectively which provides significant passage opportunities for fish including eels.” Fish can also enter from the side more easily than they can from below.

This orientation also ensures the lowest water level differential is required to open or close the doors. The weight of the door is less important when side hung than when top hung. The low headloss means that water leaves the catchment efficiently and thus ensures the maximum possible capacity in the catchment for flood events, reducing the chance of flooding. The AQUIKO doors also further benefitted from being a welded airtight construction. This ensured the doors were especially light maximising the drain capacity upstream.