Deephams Sewage Treatment Works Upgrade (2015 – 2018)

The Future of Infrastructure

Deephams is one of London’s largest wastewater treatment plants. Serving close to a million people, the site processes 230,000 tons US (209,000 tonnes) of waste daily and over 1.4 million tons US (1.3 million tonnes) during heavy rainfall. Built in the 1950s and 60s, the plant required a major upgrade including to: meet new Environment Agency wastewater standards; modernise and equip its facilities to adapt flexibly and sustainably to increased environmental pressures and the city’s growing population; and produce odour improvements.

The phased development needed to be delivered cost effectively, within Deephams’ existing footprint, and without disruption to the plant’s ongoing operations.


The project was a joint-venture (JV) between AECOM, Murphy and Kier. AECOM designed the civil, structural, tunnelling and hydraulic elements of the project. The JV team is also responsible for ongoing operations including effluent quality during demolition.

AECOM deployed innovative Integrated Fixed Activated Sludge (IFAS) technology that enables Thames Water to intensify its treatment process, and deliver cleaner water without having to expand its operations and invest in additional expensive land purchases. The IFAS media increases the surface area where bacteria can form, intensifying the treatment processes so that more sewage can be treated by fewer tanks. One of the biggest projects to use IFAS so far, Deephams reinforces the technology’s potential for projects where space and quality are at a premium.