ANDY MITCHELL: BORN 1960
THAMES TIDEWAY TUNNEL
Andy Mitchell is the civil engineeer who led for twelve years the team that built the massive Tideway sewage tunnel under the river Thames. It was completed in 2025. With a 24 foot diameter, it is big enough to accommodate a double decker bus. It carries sewage away to treatment plants east of London. At £5bn the project was the largest ever investment in London’s sewage system.
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LIFE
The following is reproduced, with acknowledgement and thanks,, from the website of the Institution of Civil Engineers at www.ice.org.uk.
Tideway workers as they began work on digging a hole with a 30m diameter on the banks of the River Thames.
ICE Felllow Sir Andrew Mitchell (also known as Andy Mitchell), has been knighted in the King’s Birthday Honours in recognition of his services to the construction industry.
Now retired, Sir Andrew led the Thames Tideway project from 2014 until April 2026, meaning he saw the project go from inception to operation.
Affectionately known as the ‘super sewer’, the Thames Tideway Tunnel was built to boost the capacity of London’s original sewer system. Built in the 1860s for a city of around 4 million people, the system struggled to cope with the almost 9 million people that now live in the English capital. Construction was completed in 2024, and the super sewer was fully connected in 2025. Since it was ‘switched on’, it has diverted 21 million tonnes of sewage from the River Thames.
Before joining Tideway, Sir Andrew worked on Crossrail (now the Elizabeth line on the London Underground) as programme director. He received a CBE in 2015 for his work on this project.
Aside from the UK, Sir Andrew has worked in France, Hong Kong, South Africa and the United Arab Emirates.
Commenting on the list, ICE director general Dr Janet Young said: “It’s wonderful to see engineers recognised for their work on projects that enable people and the planet to thrive.
“From keeping sewage out of rivers to building new hospitals and rail links, the work of our members touches the lives of people around the world every day. I am delighted to see that work being celebrated in this way.”
A graduated in engineering at Imperial College. At Crossrail, Andy was responsible for all aspects of delivering the project to create a new east-west railway under London. Previously Andy managed a number of high profile projects both in the United Kingdom and overseas.
Career
After 12 years working in the United Arab Emirates, France, South Africa and on major developments such as Hong Kong Airport and the Hong Kong West Rail he joined Network Rail in 2001. As Project Director for Network Rail's Southern Power Upgrade project, he successfully delivered the scheme £300m under budget.
He has also been Senior Programme Director of Network Rail's £5.5bn Thameslink Programme, where he led the team that secured the necessary funding and consents.
