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GTb double storm storage capacity at Southampton treatment works to prevent environmental spill

  • GTb double storm storage capacity at Southampton treatment works to prevent environmental spill

About the entity

Binnies is the new trading name for the Black & Veatch water businesses in Europe and Asia after they joined the RSK group in January 2021. Binnies specialises in water utility, infrastructure, engineering and environmental projects.


A fast-track scheme introduced by Southern Water to provide double the storm storage successfully prevented an environmental spill just three weeks’ after it was finished.

The work carried out by GTb, a joint venture between Galliford Try and Binnies, meant that all stormwater from the very next storm event was contained within Southampton’s Millbrook Wastewater Treatment Works (WTW) without a drop reaching the river or sea.  As storm conditions subsided, the stored storm water was returned to the WTW to be treated before being discharged via the permitted final effluent discharge route. By returning the stored contents of the storm tanks to the treatment process as quickly as possible, the capacity of the tanks was made available for subsequent storms.

GTb refurbished existing disused balancing tanks, making modifications to integrate them with the existing storm storage facility. The team worked collaboratively to create an additional 3400m3 of storm storage capacity. The work is contributing to Southern Water meeting the Environment Agency’s regulatory requirements to protect the Southampton shellfish waters from deterioration and to reduce storm spills into the environment.

Jorge Rodriguez, Project Manager for Southern Water said “It has been excellent to see how the work done by GTb on the storm tanks at Millbrook WTW has started improving our environment. Millbrook WTW has now more than double its storm capacity, which enabled the plant to fully contain the incoming flows, when a strong storm hit Southampton.”  The team also worked hard to have the full flow-to-treatment capacity increased in Woolston WTW by around 20%. These two sites were the ones with the highest potential to impact the quality of the shellfish waters around Southampton. I want to thank the team involved in these two projects for its commitment and hard work.”

Kennith Loftus, Project Design Lead for GTb, commented, “This project was an all-round team effort across engineering, construction and commissioning delivery teams that has enabled us to achieve this positive outcome in a very short time frame.“

Scott Aitken, Managing Director of Binnies UK and GTb Board Director, added, “Congratulations to the whole team for all their work on effectively managing the utilisation of the new storm storage capacity. It is a positive example of how investment is improving Southern Water’s performance and GTb’s important contribution.”

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