The Environment Agency is progressing its plans to reduce flood risk in Byfleet and Weybridge area in Surrey, including a Flood Alleviation Scheme for the Sanway area of Byfleet.

Flooding in Sanway in 1968 - image Environment Agency

Byfleet and Weybridge have experienced a number of notable floods in 1968, 2000 and 2003. In 2013/14 prolonged heavy rainfall resulted in flooding from the River Wey. A total of 74 properties were flooded.

Following the most recent winter 2013/14 flood, the Environment Agency reviewed options to reduce flood risk in the Byfleet and Weybridge area.

The Environment Agency has looked at a number of options, including permanent flood walls, road raising, embankments, flood gates, upstream storage and permanent defences

The appraisal identified an economically viable scheme for the Sanway-Byfleet area – the Agency intends to investigate separately options for other areas of Byfleet and Weybridge.

Sanway-Byfleet Flood Alleviation Scheme

The proposed flood defence for the Sanway area includes a combination of flood walls and flood embankments (permanent defences). The proposed defence ranges from 0.15m to 2m in height depending on whether the land is low lying. The western end of the defence will tie into the M25 embankment next to Broad Ditch

The scheme is designed to provide a standard of protection of 1 in 100 chance of flooding in any given year. This takes into account the effects of climate change. This means that in any one year there will be a 1% chance that the Sanway area will experience flooding.

Over the past few years the Environment Agency has been working with partners to develop the scheme, including:

• Woking Borough Council
• Surrey County Council
• Surrey Wildlife Trust
• Highways England
• Thames Water
• Byfleet Flood Forum

The EA has carried out computer modelling and is designing the scheme to reduce flooding to properties in the Sanway area. Flood defences that protect people, homes and businesses act as barriers to flood water. The EA also needs to create areas nearby for the diverted flood water to go without increasing flood risk elsewhere. These areas are known as compensatory flood storage areas and are included in the scheme.

The Agency is currently in the options appraisal stage of the project which is anticipated to take around 13 months.

This includes two virtual public events in partnership with Woking Borough Council and Surrey County Council earlier this month to share a number of options for reducing flooding across Byfleet and Weybridge.

A range of options will be evaluated using engineering, economic and environmental criteria. This will result in a recommendation for a single option to be delivered.

Provided the scheme is fully approved and funded, the earliest construction could be completed is autumn 2024.

Partnership funding needed

The scheme requires partnership funding i.e. sufficient funds have to be secured before detailed designs and construction can be developed.

The flood alleviation scheme will use a mixture of funding from central government, the Thames Regional Flood and Coastal Committee and local councils.

The EA commented:

“It still needs further contributions to enable construction. This is the standard way in which flood schemes are funded today.”

The cost of the scheme will depend on the options appraisal process and the preferred option. Based on current information, the Agency anticipates the scheme will cost in the region of £15.5 million. More details on costs will be available later in 2021.