The Environment Agency has published proposals setting out plans to reduce flood risk around Heathrow between Datchet and Teddington – estimated cost of construction is currently put at £302 million-plus.
The River Thames Scheme is a proposed programme of projects and investment to reduce flood risk in communities near Heathrow, including Datchet, Wraysbury, Egham, Staines, Chertsey, Shepperton, Weybridge, Sunbury, Molesey, Thames Ditton, Kingston and Teddington.
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 at risk from flooding.
The proposed 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. It also includes improvements to three of the existing Thames weirs, installation of property level products for up to 1,200 homes (to make them more resistant to floods) and improved flood incident response plans.
The River Thames Scheme will meet the recommendations set out in the Lower Thames flood risk management strategy finalised in 2009 after consultation with other public bodies, businesses and residents, and published in November 2010.
The proposed scheme will protect 9,500 properties to a 1 in 75 flood (1.33% chance of occurring in any year). In total around 15,000 properties, local infrastructure (eg roads, sewerage network) and many businesses will be better protected from flooding.
The Agency says that all communities between Datchet and Teddington will benefit from the scheme, including those downstream of the flood channel, as modifications to the weir will also reduce water levels between Walton Bridge and Teddington.
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
- installation of property level products in some homes
- 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
Thames Water is among a number of partners working with the Environment Agency on the scheme – others include:
- Elmbridge Borough Council
- Royal Borough of Kingston upon Thames
- London Borough of Richmond upon Thames
- Runnymede Borough Council
- Spelthorne Borough Council
- Surrey County Council
- Royal Borough of Windsor and Maidenhead
- Department for Environment Food and Rural Affairs (Defra)
£300m+ funding needed for scheme construction
The River Thames Scheme was originally considered to need £302 million for construction in 2009.
However, further contributions of around £50 million are still required (based on the 2009 costing) and the Agency is now working with its 7 local council partners to find the other contributions needed to build the scheme.
The Thames Regional Flood Coastal Committee’s local levy, local councils, Thames Valley Berkshire Local Enterprise Partnership (LEP) and Enterprise M3 LEP have all pledged to contribute to the scheme.
The Environment Agency is now pressing ahead with the development of the scheme, including improving flood response plans, installing property-level products and developing the design of the scheme.
Outline timeline for implementation is as follows:
- Approval of outline business case by HM Treasury - 2017/18
- Submission of planning application - 2017/18
- Approval of full business case by HM Treasury - 2019/20
- Contract award (commence construction) - 2020/21
- Readiness for service - 2024/25
- Contract completion (complete landscaping works) - 2028/29
The Environment Agency is currently working to update the costs to 2016 prices for the business case they are submitting to government. The government (subject to a robust business case) will contribute a large proportion of the funding needed for the scheme.
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