The Environment Agency is progressing with the development of the £476 million River Thames flood defence scheme - a proposed programme of projects and investment to reduce flood risk in communities near Heathrow.

The River Thames between Datchet and Teddington has the largest area of developed floodplain in England without flood defences. Over 15,000 homes and businesses within the area are currently at risk from flooding (35,000 after predicted climate change).

The scheme consists of:

• large-scale engineering work to construct a new flood channel between 30 to 60 metres wide and 17 kilometres long, built in 3 sections: Datchet to Hythe End flood channel; Egham Hythe to Chertsey flood channel; Laleham to Shepperton flood channel.
• improvements to 3 of the existing weirs on the River Thames
• improved flood incident response plans
• creation of over 40 hectares of biodiversity action plan habitat
• working with communities to raise flood awareness and support them in flood preparedness, response and recovery
• providing community resilience measures to homes and communities to make them more resistant to flooding

Major flooding in the area would cause severe disruption to the local and regional road network. It would suspend several major drinking water abstractions supplying the South East and threaten up to 20 local electricity sub-stations. The Environment Agency has calculated that damages from a major flood could exceed £850 million (£2 billion by 2055 taking into account climate change).

Many of the communities in the area have already been affected by flooding with major floods in 1947, 1968, 2003 and most recently in 2014 when approximately 1,000 homes were flooded internally.

The Agency has now published the latest updates arising from a number of discussion group workshops which took place in December 2016, together with details of a range of proposed options and concept papers.

Subject to funding, the scheme will be carried out in 2 phases. Phase 1 includes:

• developing a funding strategy for the scheme
• a hydrology and modelling study
• ecological surveys of the River Thames and specific sites
• delivering community resilience measures in some communities
• major incident planning to improve preparedness and response to flooding
• increasing the flow capacity of Sunbury, Molesey and Teddington weirs
• obtaining planning consents for the enabling works on the weirs
• securing government assurance and approvals

Phase 2 includes:

• detailed design of the scheme
• securing full, detailed planning permission and other consents for the work
• building all 3 sections of the flood channel and associated structures, and increasing the capacity of Desborough Cut

Scheme now estimated to cost £476m for design and construction phase

The scheme, once in place, will save local communities, businesses and critical infrastructure £2.3 billion in damages – a return on investment of £5 for every £1 invested in the scheme. The Environment Agency said this figure is likely to increase as further work is done to assess the positive benefits for transport and key infrastructure.

Costs of the scheme were previously based on the 2009 Lower Thames Flood Risk Management Strategy. The Environment Agency and its partners have taken the 2009 costs and updated them using construction inflation and to reflect changes in landfill tax.

The scheme is now estimated to cost £476 million for the design and construction phase -the costs will be updated as the scheme progresses.

The scheme is eligible for funding from central Government of £212 million, including Grant in Aid funding of £152 million and an additional investment of £60 million. Partnership funding of over £36 million has also been secured. The River Thames Scheme partners are exploring all opportunities to secure the additional funding required. The leader of Surrey County Council has set up a funding group, which will target beneficiaries and seek contributions

Timescales for the scheme are currently as follows:

1. Approval of outline business case by HM Treasury - 2017/18
2. Submission of planning application - 2017/18
3. Approval of full business case by HM Treasury - 2019/20
4. Contract award (commence construction) - 2020/21
5. Readiness for service - 2024/25
6. Contract completion (complete landscaping works)-  2028/29

Click here to access the latest update documents

Waterbriefing is media partner with the Environment Agency’s major three-day conference and exhibition Flood and Coast 2017 which takes place from 28^th to 30^th March 2017 in Telford.  Click here  for more information