The Mackley-Jones joint venture, doing business as Future Water MJJV, will build Havant Thicket Reservoir for Portsmouth Water.
It will be the first large-scale new water storage reservoir in the UK since the 1980s and is being developed by a partnership between Portsmouth Water and Southern Water.
As previously reported, Ward & Burke Construction has a £41m contract to put in tunnelled pipelines to and from the reservoir.
Portsmouth Water chief executive Bob Taylor said: “This is a major milestone for the Havant Thicket Reservoir project, and we are delighted to have these two exceptional contractors delivering the scheme.
“We were highly impressed by the proposals put forward by Future Water MJJV and Ward & Burke during the tender process, with both companies being able to call upon vastly experienced teams, with strong track records in successfully delivering major infrastructure.”
JT Mackley & Co is part of the Dutch maritime engineering and dredging group Van Oord.
Future Water director John Dielhof said: “It’s a project that we can’t wait to get started on because we know how much of a positive impact it will have on the region. The scheme will safeguard dozens of jobs for our skilled workforce, as well as create opportunities for apprentices and trainees to kickstart their civil engineering career with us.”
Once completed – which is expected in 2029 – Havant Thicket Reservoir will hold 8.7 billion litres of water and be able to supply up to 21 million litres of water each day. It will be one mile from east to west, half a mile from north to south, with a new wetland on its northern shore. It is being built on a 160-hectare grassland site that has been owned by Portsmouth Water since the mid-1960s.
A two-mile long pipeline, which is designed to be largely tunnelled, will also be built to fill Havant Thicket Reservoir in the winter with surplus water pumped from nearby Bedhampton Springs. It would also be used to draw water from the reservoir to supply customers when it’s needed.
The reservoir was granted formal planning permission in October 2021, with a further planning application for the new pipeline expected to be submitted in summer 2023.
Portsmouth Water will finance the Havant Thicket Reservoir scheme through a combination of £150 million of equity funding, provided by investors in the company’s owner Ancala Partners, as well as money that will be borrowed. £120 million of the equity funding will be used this year, with a further £30 million to follow in early 2024.
Ofwat, the water industry regulator, recently approved a revised budget for the scheme. (The main works contract was previously estimated at £100m not £167m.) This has enabled Portsmouth Water to award the two main design and construction contracts for the project, with further contracts, including for a new visitor centre at the reservoir, to be awarded in the coming years.
Bob Taylor added: “‘The final decision from Ofwat on the project’s updated budget will ensure the reservoir scheme can be funded and deliver good value for money for customers, while safeguarding water supplies and supporting nature.
“The innovative regulatory and commercial approach that’s being taken has enabled us to deliver cost-effective local solutions to regional water resources challenges. We would like to thank our colleagues at Ofwat and Southern Water for their excellent collaborative work.”
Ultimately, Havant Thicket Reservoir will be paid for by Southern Water customers, through their water bills.