The first phase of the Leeds Flood Alleviation Scheme has reached a major milestone as all three moveable weir gates have now been successfully put in place at Knostrop Weir on the River Aire.

Costing in the region of £50 million, the scheme is being led by Leeds City Council in partnership with the Environment Agency.

Final stages of the work at Knostrop include the removal of the remaining cofferdam ahead of it becoming a fully operational flood defence later in May.

The three gates have been constructed as part of an innovative approach using moveable weirs, which can be lowered in flood conditions to reduce river levels and the threat of flooding. This is the first time that moveable weirs are being used in the UK for a flood defence.

The weirs can be lowered, and raised, by deflating and inflating ‘bladders’ fabricated from a bullet proof neoprene material under each gate, which act like giant air filled pillows.

The first of the weir gates at Knostrop Weir has already been tested. Later this month the cofferdam structure, which was installed to allow a dry working area in the river for the construction of the weir gate, will be flooded with water and the sheet piles then removed.

Moveable weirs are also being constructed further upstream at Crown Point in the city centre, where the installation of the first of two weir gates has been completed. Last month, reinforced concrete works were finished which meant the bladders and gates could be fixed in place prior to testing.

Now this gate has been installed and tested, the cofferdam has been flooded and the sheet piles are being removed to allow for work to begin on the final weir gate adjacent to Fearns’ Island.

Leader of Leeds City Council Councillor Judith Blake said:

“The value of the Leeds Flood Alleviation Scheme in terms of the reassurance it will offer residents and businesses over the coming years and decades is incalculable, so we very much look forward to seeing phase one complete later this year while we continue to make the strongest possible case for further significant measures to help protect all our communities threatened by flood-risk across the city as soon as possible.”

The site works for Phase 1 of the Leeds Flood Alleviation scheme, one of the largest river flood defences in the country, commenced in January 2015 and are due to be completed this summer.

Work on Phase 2 of the project is currently underway to develop a proposal for how to increase the standard of protection in Leeds including areas such as Kirkstall and Stourton. Leeds City Council has awarded a contract for a feasibility study which will look at the viability of the options looked at in the scoping study.

Work to develop a full business case, which will establish the appropriate standard of protection for Leeds, how this can be achieved, what it will cost and how long it will take to deliver is now progressing.

The business case is expected to be submitted in autumn 2017, following which the outline design will be progressed with a view to tendering and awarding a construction contract in summer 2018.