Sanway-Byfleet Flood Alleviation Scheme

Closes 11 Mar 2024

Opened 22 Feb 2021

Overview

This web page has been set up to share information about the Sanway-Byfleet Flood Alleviation Scheme. We welcome your feedback and questions on our proposals via our online survey or by using the contact details on the right-hand side of this page.

The scheme is being developed by the Environment Agency in partnership with Woking Borough Council, Surrey County Council, Surrey Wildlife Trust, Byfleet Flood Forum, Highways England, Thames Water, and the local community.

In February 2019, we held public events to share a number of options for reducing flooding across Byfleet and Weybridge. These events enabled us to answer your questions and collect feedback.

Since then, we have been working on developing our proposals for the Sanway-Byfleet area in particular. On this page, you can view our proposed flood defence alignment and read about our proposed options for community and environmental opportunities in the area.

We are currently in the ‘options appraisal’ stage of the scheme and any feedback we receive will help us to amend our plans where appropriate. We will share the findings of our options appraisal and seek your views on this before selecting a preferred option for the scheme.

Due to the current Covid-19 restrictions, we are unable to hold face-to-face information events like we did in February 2019. Instead, in March 2021 we held two virtual events in partnership with Woking Borough Council and Surrey County Council. 

  • Virtual event session 1: Saturday 13 March 2021
  • Virtual event session 2: Wednesday 17 March 2021

You can download a copy of the slides from the events.

If you were unable to attend a virtual event, we would still like to hear your feedback on our proposals via our online feedback form or the contact details above. You can also contact us at any time if you wish to discuss the scheme.

 

More Information

The below map shows the area covered by the scheme, including Broadoak Weir which is southwest of the Sanway-Byfleet area. You can also download a PDF of the plan.

More Information

Byfleet has a long history of flooding, with the large September 1968 flood causing significant damage to properties along the River Wey. It was one of the largest floods seen in this area and was estimated as being a 1 in 200 chance of flooding event.

The below photograph shows the extent of the flooding.

Sanway-Byfleet during the 1968 flood

Extent of flooding in 1968

Byfleet has seen the effects of flooding in more recent years, with notable floods in 2000, 2003 and 2013/14.

Many Sanway and Byfleet residents will remember the flooding in winter 2013/14, when we experienced some of the heaviest rainfall and highest flows on the River Wey in recent history. Many properties were flooded, with the Sanway area particularly badly affected. Around 80 homes in the Byfleet area suffered flood damage.

The below map shows the current possibility of flooding for the area. You can also download a PDF of the plan.

The following map shows the possibility of flooding for the area, taking climate change into account. You can also download a PDF of the plan.

Following the most recent floods in 2013/14, we have reviewed the options to reduce flooding in the area. This scheme aims to reduce flooding from the River Wey for up to 153 properties in the Sanway-Byfleet area by using a flood defence. The defence is designed to provide a standard of protection from a 1 in 100 chance of flooding in any given year, taking into account the effects of climate change. This means that in any one year there will be a 1% chance that the area will experience flooding.

More Information

In February 2019, we held public events to share our initial proposals for reducing flooding across a larger area of Surrey, which included Byfleet and Weybridge. The events enabled us to answer your questions and collect feedback. You can download a copy of the boards used at the events.
Since we last shared information with you, we have been undertaking more detailed work on the proposals for the scheme and listening to our partners and key stakeholders. This work included:
  • Extending the alignment for the flood defence so that it will provide a standard of protection of 1 in 100 chance of flooding in any given year, taking into account the effects of climate change. This means that in any one year there will be a 1% chance that the Sanway-Byfleet area will experience flooding. More detail about the flood defence can be found in the section below called ‘our current proposals’.
  • Speaking with Highways England to explore opportunities for working together as part of this scheme and the M25 Junction 10 Improvement Scheme.
  • Holding a workshop on potential environmental benefits the scheme could create with key stakeholders and the local community.
  • Developing ideas for community and environmental opportunities to complement the flood defence. More detail about this can be found in the section below called ‘community and environmental opportunities’.
  • Working on proposals for fish passes to allow migration of fish over a greater length of the River Wey.
  • Assessing options for Byfleet Mill Weir as it is in poor condition and reaching the end of its life.
  • Carrying out a number of surveys to help us understand more about the area around the river.
Surveys
We are carrying out the following surveys:
  • Topographic surveys to understand the physical features and elevation of the land and river channels.
  • Ground investigation surveys to understand what the ground is made of, which will help us design the flood barrier and understand the impacts on groundwater. This will include a combination of small trenches and boreholes. When we have drilled a borehole into the ground, we then install equipment to monitor groundwater levels. The equipment remains in place for around 12 months.
  • Ecological surveys to understand what habitats are in the area and if there are protected species such as Great Crested Newts and bats present to ensure we can design the scheme to accommodate them.
  • Arboricultural surveys to assess the quality of trees in the area.
Photo of topographic surveys carried out in January 2021
Topographic surveying January 2021
 

More Information

To reduce flooding from the River Wey, we propose to install a combination of flood walls and flood embankments (known as a flood defence). Embankments and flood walls protect homes by acting as barriers to flood water.
The flood defence will range in height depending on whether the land is low lying. The western end of the defence ties into the M25 embankment next to Broad Ditch and runs east in Common Meadow along the rear boundary of properties in the Fullerton Road and Sanway Road area. The defence then runs northwards to protect properties in Summer Close before petering out on higher ground.
The flood defence will not increase flood risk to other areas because the scheme will also involve the creation of new areas of “compensatory floodplain storage”, which will hold the flood water that is displaced by the flood defence.
The scheme aims to reduce flooding for up to 153 properties in the Sanway-Byfleet area. The defence is designed to provide a standard of protection of 1 in 100 chance of flooding in any given year, taking into account the effects of climate change. This means that in any one year there will be a 1% chance that the area will experience flooding.
The plan below shows the indicative alignment of the flood defence and the areas where we are considering having compensatory floodplain storage. You can also download a PDF of the plan.
As part of the further development of the project in this stage, we will confirm the exact alignment of the flood defences which could result in some changes being required to what you see here.
Plan of flood wall alignment and compensatory storage target areas

More Information

While the aim of the scheme is to reduce flooding, we also have an opportunity to deliver some wider benefits to the community and the natural environment in the area.
In January 2020, we held a workshop focused on potential environmental benefits the scheme could create. 50 people attended, including local residents, the Byfleet Flood Forum, landowners, environmental experts, the Environment Agency, local councillors, and local council officers.
Following this, we have been working on various options for creating community and environmental opportunities. We welcome your feedback on these options to help us consider which options to take forward. We will also be completing more work to understand how viable these options are and will need to take into account funding.
The following options could be possible in the area:
Community space and access
  • Creating more open accessible space for the community.
  • Creating and improving the range of footpaths so they are more accessible.
  • Creating a new footpath next to the alignment of the proposed flood defence.
  • Planting more trees, flowers and hedges.
  • Introducing viewing points and bird watching hides.
  • Providing more green space to the west of the M25 with links to the surrounding footpath network.
  • Improving the existing M25 underpass.
  • Improving the Broad Ditch, which is an important stream that feeds into the River Wey.
Habitats
  • Creating a mosaic of seasonal wetland habitats on Common Meadows to encourage a range of wildlife, including ponds, wet meadows, and wet woodland.
  • Installing boardwalks to travel through wetland areas, enabling people to enjoy the surroundings without disturbing wildlife.
  • Restoring and enhancing habitats and natural river processes within the River Wey and Broad Ditch channels and reconnecting it to its floodplain.
Fish passes
  • Creating fish passes at Byfleet Mill Weir and Broadoak Weir to enable fish to migrate upstream for 32km to previously inaccessible habitats including spawning areas (areas to lay their eggs).
Example photos of wet grassland in Exeter (top) and Marlow (bottom)
Example image of wet grassland
Image 2 of a wetland habitat
In addition to these community and environmental opportunities, we are also considering the following proposals.
Byfleet Mill Weir

There are currently sluice gates at Byfleet Mill Weir, which enable us to control the level of the river to adapt to different flow conditions. However, these are in poor condition and are reaching the end of their life.

We are considering options for Byfleet Mill Weir, which could include:

  • Replacing the existing gates, which would maintain the water level upstream of the weir.
  • Replacing the existing gates with a structure at a lower elevation (such as a weir), which would result in water levels lowering upstream by around 0.5 metres.
  • Removing the existing gates, which would result in water level lowering upstream by around 1.5 metres.
  • Removing the existing gates and some of its concrete structure, which would result in the lowering of water levels upstream by around 2 metres.
Surface water flooding
We are looking at sustainable opportunities to manage surface water flooding in the Sanway-Byfleet area as part of this scheme.
Sustainability
We will assess the sustainability of all aspects of the scheme and this will be used to inform the preferred option we take forward.
The scheme will aim to reduce carbon emissions as much as possible, such as to minimise the use of single use plastics where possible.  
We will also aim to deliver a minimum of 20% biodiversity net gain, meaning that we will leave the environment improved following the scheme.

More Information

The scheme requires partnership funding, meaning sufficient funds have to be secured before detailed design and construction can be developed.
The scheme will use a mixture of funding from central government, Thames Regional Flood and Coastal Committee and local councils, but it still needs further contributions to enable construction. This is the standard way in which flood schemes are funded.
We will also aim to secure partnership funding for the community and environmental opportunities.
The cost of the scheme will depend on the options appraisal process and selection of the preferred option, including the community and environmental opportunities. Based on current information, we anticipate the scheme will cost in the region of £12 million to £16 million. More details on costs will be available later in 2021.

More Information

We’d like to hear your views on our proposals and answer any questions you may have. You can do this by:
We’re currently working on our outline design for the scheme, which includes evaluating our options using engineering, economic and environmental criteria so that we can select a single preferred option. This is known as the ‘options appraisal’ stage. Any feedback we receive from you at this stage will help us to amend our plans where appropriate.
We will share the findings of our options appraisal with you and seek your views on this before selecting a preferred option for the scheme.
We will then seek funding approval for the next stage, which is known as ‘detailed design’.
Before construction begins, we must make sure that all approvals, such as planning permission, are in place. Provided the scheme is fully approved and funded, the earliest construction could be completed is autumn 2024.

Audiences

  • Members of the public

Interests

  • Flood management