Project outline

Deephams Sewage Treatment Works (STW) is one of the largest waste water treatment plants in the UK and was upgraded between 2013 and 2019 to accommodate a 989,000 population equivalent.

Murphy, as part of the AECOM, Murphy and Kier joint venture (AMK), was contracted by Thames Water to carry out the Deephams STW Upgrade. The aim of the project was to improve the quality of effluent released into the River Lee, to comply with more stringent Environmental Agency standards, and to reduce odour levels by 90%. We also needed to increase the capacity of the site, to facilitate a future population rise.  

The works included new treatment structures and plant, odour control plant, improvements to waste gas recovery, energy generation and new facilities for operations staff.

We have also previously completed the Deephams Inlet Works Improvements for Thames Water in 2011. Due to our use of more sustainable and innovative construction methods on this project, we saved 10,000 tonnes of carbon and £2.2million (excluding whole lifecycle costs savings).  

Project delivery/innovations

• The project performance was underpinned by an excellent Health & Safety record - 3.7 million accident and incident free hours.
• The demolition and construction of the plant was split into phases, to ensure the plant remained operational at all times. Initial bolstering works meant that sewage was treated continuously, while up to a third of the works was out of service.
• All soil and concrete waste remained on site and was recycled as backfill. This waste control strategy meant there was less traffic, and therefore less noise and vehicle pollution. We saved approx. 640 tonnes of CO₂e.
• Integration of our unique in-house capabilities, including Murphy Process Engineering, Murphy Ground Engineering, Murphy Plant and Murphy Electrical, ensured this was a ‘One Murphy’ project in full collaboration with our joint venture partners.
• Many of the large structures were fabricated using off-site pre-cast solutions, such as the new treatment structures. This saved many weeks of construction time and provided assured quality on site.
• Innovative thinking prevailed throughout, for instance, the team developed a solution to use an in-channel pumping station to protect the storm tanks from high river level surges, as opposed to a more conventional wet well system.
• The team proposed a more sustainable dewatering process, to abstract 20l/s from local ground sources rather than the 150l/s initially planned. The 87% reduction saved 2.4 billion litres of water.

“Our focus at Deephams was to carry out the works with little disruption to the operation of the plant and its treatment capability, as it was kept live throughout the project.”

Andrew Chappell
Murphy Project Manager

The impact

The new works uses two thirds of the original site footprint and has freed up land for Thames Water to potentially build more treatment facilities on site in the future.

Heat and power from the plant’s waste gas production also generates an additional revenue stream for Thames Water, which has reduced operational costs and their reliance on the National Grid supply.

The River Lee flows cleaner and provides a much healthier environment for aquatic and other wildlife. The improved riverside environment and a reduction in odour levels has delivered a healthier environment for the local community.

The project received industry recognition, by winning “the Greatest Contribution to London” award at the 2019 Institution of Civil Engineers London Awards.