More major milestones targeted in huge project to create a new water reservoir at Havant Thicket

Works on the embankment of the reservoir are expected to start later this year, with around 60 per cent of the groundworks now completed which has seen the team dig into the thicket, and then use clay to create a solid base to stop the water from leaking out.

And with progress continuing apace, it is expected that this will be completed later this year - allowing the Portsmouth Water-led team to move on the embankment works.

A culvert has also been created, which is a tunnel which contains key equipment, as well as an ‘wall’ which will also go underneath to also help prevent water from escaping and will eventually be submerged underneath the reservoir when it is filled with water.

Ruari Maybank, Portsmouth Water’s Havant Thicket Reservoir project director, said: "This time last year we started our big build phase of the project. In the last year we have been focused in construction terms on the ground improvement zone and the culvert.

"The ground improvement zone is like the foundations for the reservoir, so when that's complete it will be about 3,000 meters long. And to build that, we need to dig down about two meters and then replace the material in the ground with clay that we lay down really carefully in a series of layers.

"The culvert is a concrete tunnel and the role of that concrete tunnel is to hold the values and the pipes that we'll use to draw water out of the reservoir when we need to supply water to Southern Water's customers.

"Last year we completed most of the culvert, and when that's complete it will be 230 metres long, about seven meters wide and about six meters tall.

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"(This year) we will also complete the ground improvement zone. We completed about 60 per cent last year, this year we will complete those foundations and then later this year we will start to build the reservoir embankment up, one layer at a time. That is going to take several years to complete."

The next phase of the project, which will also begin later this year, is the start construction of the dual pipeline linking the reservoir to Bedhampton Springs which will be its primary source for water.

Mr Maybank explained: “The pipeline will enable us to supply water to the reservoir site from Bedhampton Springs, and most of that is going to be using tunnelling techniques which means we don't need to disrupt local residents and businesses by digging trenches through the streets of Havant.”

More details about this work is due to be shared in coming months as well as the final details of how the site will look, including southern access road, landscaping and the ‘jewel in the crown’ which is its visitors’ centre.

The new water reservoir is expected to be operational and fully open to the public in the 2030s.

Watch the video embedded in this story to find out more

• When complete, the Havant Thicket Reservoir will be the first major new UK reservoir built in over 30 years and enable it to supply drinking water to both Portsmouth Water and Southern Water customers as needed.
• Once completed, the reservoir will hold up to 8.7 billion litres of water and reach a depth of 22.1 metres at its deepest point.
• The reservoir site will also feature footpaths for walking, as well as routes for cycling and horse riding, facilities for bird watching, picnic and play areas and car parking. There will be a visitor centre with a café, toilets and space for community and education activities.
• The project includes separate off-site environmental works involving improvements to Southleigh Forest, converting 80 hectares of local agricultural land into woodland, wood pasture and grassland, and a capital grants scheme for local environmental projects.
• Micro-tunnelling will be used to build the majority of the reservoir pipelines, with two ‘open cut’ sections, where a trench will be dug to put the pipelines in and cover them up again.
• One pipeline will be used to carry surplus spring water to the reservoir in winter, where it will be stored. The other pipeline will enable water to be taken out for supply to customers during a drought or emergency situation.
• In the future, the pipelines could also carry purified recycled water, should Southern Water receive approval for its Hampshire Water Transfer and Water Recycling Project which has been the subject of some controversy.
• The reservoir itself is being constructed by Future Water MJJV Ltd, a joint venture between leading civil engineering contractors Mackley and Jones Bros, with over 150 years of combined experience in complex civil engineering projects.