Costain JV secures £65m contracts with Southern Water

A Costain and MWH Treatment joint venture, CMDP, has been awarded several multi-million-pound contracts by Southern Water.

The £65 million combined work is part of Southern Water’s AMP7 investment programme which runs until next year before being replaced by AMP8 in April 2025.

Costain recently won a design and build contract to upgrade two Thames Water treatment sites, while MWH were named as part of a £2.7 billion water network upgrade.

The projects will see the joint venture aim to improve the resilience of the local water supply as well as upgrade wastewater treatment works at Testwood near Southampton and Burham in Kent. 

The integrated CMDP team is set to work with Southern Water and engineers across both sites to develop cost-efficient solutions, optimise asset performance and deliver the implementation through to the end of AMP7.

The aim is to see major renovation, refurbishment and expansion of existing assets across both sites to cope with rising demand for drinking water and increasing volumes of wastewater.

The Water Services Regulation Authority (Ofwat) reported that population growth directly contributes to the increased scarcity of and demand for water.

Planned improvements at Testwood Water Supply Works include:

• refurbish and make improvements to abstraction points from the River Test, pumping stations and flow and filtration assets
• upgrade the rapid gravity filtration facilities and repurpose contact reservoir tanks at the site

Planned improvements at Burham Water Supply Works include:

• full refurbishment of the low lift pumping station and granular activated carbon filters
• site-wide chemical dosing upgrades
• upgrades to improve the resilience of the water treatment works, i.e. increasing the usable volume of the lake that feeds the site

Chris Hodgson, programme director for the CMDP-JV, said: “This is important work that will have a transformative impact on the lives of residents and local communities.” 

Tim McMahon, director of water at Southern Water, said: “We have an excellent track record of working with Costain as part of the CMDP joint venture and we are looking forward to collaborating with them once again for this crucial work. 

“With a changing environment and a growing population, it is important that we make strategic investments to upgrade facilities and ensure they are fit-for-purpose for the long-term.” 

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