Grasscrete green solution for armoring spillway slopes

The project

East Riding of Yorkshire Council's Pocklington Flood Alleviation Scheme required an armoured spillway leading to a flood storage bund capable of withstanding flow rates of up to 8 metres per second. With a new housing development next door, there was a need to tone down the engineering impact.

The solution

Grass Concrete's Grasscrete was selected to armour the slopes of the spillway.

Going green might be something of a cliché, but that’s exactly what happened with the Grasscrete spillway slopes being cast with green coloured concrete.

The combination of flexible void formers and cast-in-place concrete, enabled contouring up to the crest beam to create a smooth curved transition to aid flow efficiency. With a flow capability of 8 metres per second, the Grasscrete facing to the spillway allows overspill from the storage area to be collected in the stilling basin before its transfer to the adjacent beck.

Topsoil from the site strip was stockpiled ready to infill the Grasscrete pockets, enabling local pH values to be maintained. The level concrete surface enabled the soil to be bladed into the pockets. Swift grass growth was established alongside the ‘toned down’ green concrete.

The outcome

The flood bund created a barrier between the flood storage area and the open fields to Persimmon Homes’ new housing development.

Pocklington Flood Alleviation Scheme (POCFAS) is the latest flood prevention scheme introduced by the Council, which along with the other schemes has collectively provided protection for up to 23,000 homes. Now complete the storage area created by the bund is capable of holding 90,000 cubic metres of flood water, to mitigate the risk of downstream flooding in the Pocklington town centre and its surrounding neighbourhoods.