Severn Trent has appointed engineering contractor Costain to deliver a major upgrade to Rugby Newbold Sewage Treatment Works, a project designed to boost the site’s capacity and resilience ahead of tighter environmental requirements in the eighth asset management period (AMP8).

As principal contractor and principal designer, Costain will design and build a new activated sludge plant – a biological treatment system that uses microorganisms to break down organic material – and integrate it with the existing site. The work is expected to increase the works’ permitted dry weather treatment capacity by 28%, from 21,600m3 per day to 27,598m3 per day, by 2028.

The expansion is intended to ensure the treatment works meets AMP8 Winep obligations. The Water Industry National Environmental Programme (Winep) sets environmental interventions for water companies during AMP8, the current five-year regulatory period, and requires some sites to accept or treat higher volumes of dry weather flow to cope with changing weather patterns and regulatory expectations.

In addition to the activated sludge plant, the programme will include new pumping stations, four final settlement tanks each about 29m in diameter, and a chemical dosing plant. Costain will also expand and upgrade the inlet works, increase feed and storm capacity and upgrade various utility and facilities systems. Severn Trent said the two companies will work collaboratively to mitigate risks to the site’s inlet during construction.

The scheme is valued at roughly £45M and is scheduled to run through to 2028. Costain has said it will apply its “Production Thinking” approach – combining off-site manufacturing, design for manufacture and assembly (DfMA) and digital technologies – to seek efficiencies and reduce on-site construction time.

Sewage treatment capacity is coming under renewed focus as regulators press water companies to improve resilience and environmental performance after a series of pollution incidents in recent years. Increasing the ability of plants to cope with higher dry weather flows is one way companies can reduce the risk of unpermitted discharges during periods of fluctuating demand or storm events.

Matt Bateman, water sector director at Costain, said: “We have a long-term trusted partner relationship with Severn Trent and are looking forward to once again having the opportunity to deliver high quality infrastructure upgrades quickly and safely. This award is built on our excellent track record of identifying construction efficiencies and delivering best-in-class solutions that maximise value for Severn Trent and its customers.”

Andrew King, delivery business lead at Severn Trent, said: “We are delighted to be working with Costain to help deliver these essential upgrades, that will bring a huge benefit to the way the site operates. These upgrades will see our Rugby wastewater site be able to hold even more rainwater during storms, meaning less chances of issues such as flooding or the use of overflows. The piece of work will see us working collaboratively with Costain in areas, utilising different technologies and ensuring that the site serves the local area to the very best capacity.”

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