Abstract

The Lee Tunnel in London is the first of two tunnels, which will collectively capture an average of 39 million tonnes of sewage a year from the 35 most polluting combined sewer overflows (CSOs), built by the Victorians as part of a sewerage network that still serves London 150 years on. The project required boring London’s deepest-ever tunnel through high groundwater pressures and passing through four miles of the most abrasive ground, without any other shafts along the way. The tunnel will help prevent more than 16 million tonnes of sewage mixed with rainwater overflowing into the River Lee each year, by capturing it and transferring it to Beckton Sewage Treatment Works, which is being expanded by 60 per cent to enable it to deal with the increased volumes.

This very large project required the building of a drilling machine specifically designed for the Lee Tunnel. In 2012, the drilling machine Busy Lizzie began boring the seven-metre diameter tunnel, which is the width of three London buses. Tunnelling was finished in January 2014. The talk will focus on the engineering activities and the progress made to deliver a sewage system to rival and excel those built by our Victorian predecessors.