The Thames Tideway Tunnel is a proposed solution to London’s sewage overflows into the River Thames. The $5.8 billion, 15.5-mile tunnel will descend 213 feet below ground, running from Acton to the Abbey Mills Pumping Station in Stratford, essentially under the river. It will collect diluted sewage that currently pollutes the Thames.

Thames Water customers will pay for the tunnel through their water and sewerage bills. Engineers originally designed London’s sewers to overflow about 12 times a year; however, it now happens around 60 times instead. Combined-sewer overflow sites pollute the Thames, and London is in violation of European standards for handling waste water.

The project is currently underway. Planning approval was given in 2014, financing secured in 2015, and tunneling began in 2017. Completion is expected by 2023.

When the tunnel was first proposed in 2005, it was estimated to cost $2.3 billion. The current estimate is triple that. Professor Chris Binnie, who led the original study in 2005, now says the project is a waste of money.

The tunnel will be owned by a new company, Thames Tideway Tunnel Ltd., a unit of “infrastructure provider” Bazalgette Tunnel Ltd. The firm will be paid for building, operating and maintaining the super sewer. Once the tunnel is finished, the company will supply sewerage services to Thames Water on a 125-year concession.

Angelica Obioha, Infrastructure-Info Staff