The tunnel, which would run beneath all other infrastructure under the capital, would transfer the sewage that currently spills into the tidal Thames, to Beckton Sewage Treatment Works in east London, linking up with the Lee Tunnel, which is already under construction.
Currently up to 39 million cubic metres of raw sewage is discharged annually into the tidal Thames by Combined Sewer Overflows (CSOs).
The Environment Agency has identified 34 “unsatisfactory” Combined Sewer Overflow points built into the existing sewer network that the proposed tunnel needs to address. These CSOs cause adverse environmental impacts on the River Thames.
Environment Agency chairman Lord Chris Smith said: “The River Thames has improved significantly over the last 20 years, but further improvements are needed to deal with the unsatisfactory overflows of sewage.
“London’s sewerage network has nearly reached its capacity. In future due to increased population and volume of sewage it will exceed its capacity. This will steadily worsen the impact of the overflows as they will spill sewage more frequently into the river.”
“Doing nothing is not an option. We consider the Thames Tunnel the best solution available to limit pollution from sewage in the Thames. “
“We will continue to work closely with both the Government and Thames Water as the second phase of consultation progresses over the next 14 weeks.”
Thames Water launched a 14-week consultation on its updated list of preferred sites for the tunnel’s construction and operation on Friday.