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Flood Alleviation Scheme

Update – May 2014
 

The main works contract (City centre and Holbeck) is now out to tender. The tenders are due to be returned towards the end of July and it is anticipated that this contract will commence in August. All works are programmed to be completed before the end of 2016.

The city centre landscape drawings are now available to download from the Documents tab located on this webpage:

  • ‘LFAS Landscape Drawings Index’ – contains an indexation of the drawing locations
  • ‘LFAS Landscape Drawings’
The Leeds Flood Alleviation Scheme Fly Through, via YouTube, is now available to view on this web page. The Crown Point Weir animation can now be accessed via the External Links section.

Woodlesford

The Woodlesford Enabling Works have been awarded to BAM Nuttall Limited. The works are currently underway and are due to be completed in July 2014.


Knostrop Quay (KQ) Arm /Old Mill Lane Basin Adjacent to the H2010 Development

Knostrop Quay enhancement options continue to be developed. Further discussion with stakeholders is necessary to fully evaluate the options in this area before we will be in a position to consult members of the public on the proposals. There will be further consultation with the residents of the H2010 development on the draft details before the plans are finalised.

 
Background

Flood risk is increasing throughout the UK and in recent years Leeds city centre has come close to flooding several times.
There are currently no formal flood defences along the River Aire and in order to ensure and support further growth and regeneration of the Leeds economy, a flood defence scheme is needed to help protect the homes, businesses and transportation networks of Leeds.

Scheme Proposals and Project Details

Leeds City Council, working alongside the Environment Agency, the Canal and River Trust and other partners, are developing proposals to protect Leeds city centre (between Leeds station and Knostrop weir) from a flood event likely to happen once every 75 years. The likelihood of a 1 in 75 flood event occurring in any given year is 1.3%. (See ‘Flood Alleviation Scheme FAQ’ in the Documents section of this page for more details).

The proposed 1 in 75 flood protection scheme will:

  • Remove the existing weirs at Crown Point in the city centre and at Knostrop Cut and install moveable weirs that can be lowered when the river is high, causing the water level to drop. An animation showing the typical operation scenario of the Crown Point weir can be seen, via youtube, by using the ‘Crown Point Weir’ link under the external links heading;
  • Construct landscape defences such as low level embankments, terracing and riverside walls; at low points along the riverbank;
  • Remove Knostrop Cut to merge the Canal and River Aire which will create additional flood water storage and help to lower water levels in flood conditions;
  • Provide flood defences along a length of Holbeck located on Water Lane;
  • Provide defences to Woodlesford in the form of low level embankments to achieve a protection against a flood event that is likely to occur every 200 years.
Planning permission for the movable weirs has been granted. Details for this can be viewed by using the ‘Planning Permission Weirs on the River Aire’ link under the External links heading.

Funding and Programme

The scheme is estimated to cost in the region of £50.5m and is being funded through a partnership supported by Defra and the Treasury, Leeds City Council and local businesses. This work is due to start during 2013/2014 and be completed in 2016.
 
The following documents are available to download in the ‘documents’ section of this page:

  • A leaflet showing the general overview of the full scheme - Leeds Alleviation Scheme Leaflet
  • Location Plan - Full Scheme Overview (CC-001)
  • Scheme Overview - City Centre (CC-002)
  • Scheme Overview - Knostrop Cut (CC-003/CC-004)
  • Scheme Overview - Woodlesford Defence Proposals (CC-010)
  • Scheme Overview - Holbeck Flood Defence Proposals (CC-011)
  • City Centre Flood Defence Proposals (CC-005 to CC-009)
  • Landscape Drawings (Location Plan/Landscape Drawings) (CC-200, CC-201-CC218)
  • LCC 1 in 75 Flood Event Risk Boundary - added 13 February 2014
  • Contract Drawings CC0001-CC0007 - Added 12 March 2014
  • Contract Drawings CC0008-CC0012 - Added 12 March 2014
  • Contract Drawings CC0013-CC0018 - Added 12 March 2014
  • LFAS Landscape Drawings Index -  Added 12 May 2014
  • LFAS Landscape Drawings -  Added 12 May 2014

What level of protection is provided by the scheme?

The aim is to provide a 1:75 standard of protection against flooding.

What do we mean by flood risk?

This is the chance of a flood happening. Generally, the higher the figure used in the description of the flood risk, the less chance of it happening. For example:

An area with the chance of flooding of a 1 in 75 (1.3 percent) in any one year has less chance of flooding than anothe either; a ‘chance’ (i.e. a 1 in 75 chance of flooding in any one year) or a ‘probability’ (i.e. a 1.3 percent annual probability of flooding village with a 1 in 25 chance (4 percent) in any one year.

It is important to understand that a 1 in 75 chance of flooding in any one year does not mean that level of flood will happen once every 75 years. Nor does it mean that if the flood hasn’t happened for the last 74 years, it will happen this year. ‘Any one year’ means exactly what it says, in that the risk is expressed on a yearly basis. A flood may also occur more than once in a year.

Why has this level of protection been chosen?

The current agreement Government has with the Association of British Insurers (ABI) is that ABI members make flood insurance for domestic and small businesses available as a feature of standard household and small business policies if the flood risk is no significant - this is generally defined as no worse as 1 in 75 annual probability of flooding.

How long will it take to build the defences?

The aim is to have the first phase of works completed by June 2015.

Will boaters be affected by the proposals?

No, the weirs will only be lowered during actual events and when the speed and depth of water in the navigation is too great.

How does the introduction of movable weirs improve flood protection?

The river level is held artificially high by the existing weirs which were built to allow navigation. The proposed movable weirs will, in a flood event allow the river levels to drop by up to 1.0m.

What about flood protection upstream of Leeds Station?

The scheme will protect the city centre section and not sections upstream of the train station. Future phases will include addressing flooding upstream of the station, however, these will be subject to the availability of future funding.

Will flooding risk be increased further downstream?

The scheme will have an immeasurable effect on the risk of flooding downstream of Thwaites Mill. There are large areas of designated floodplain from the Mill downstream.