Thames Water head of London Tideway Tunnels Phil Stride is to meet independent consultant Chris Binnie to discuss his recent outspoken criticism of the scheme’s development.
Stride told NCE this week that he was “frustrated” by Binnie’s decision to cast doubt in the media on the mega-scheme’s design and had sought a face to face meeting.
The mega-sewer is to be a stormwater storage tunnel under the Thames between Acton in west London and Beckton in the east. Stormwater will be treated at Beckton Sewage Treatment Works before it is released back into the river.
“Why didn’t [Binnie] come to us and ask ‘what have you been doing over the last five years’?”
Thames Water head of London Tideway Tunnels Phil Stride
Binnie told the BBC last week that Thames Water should reconsider whether the proposed tunnel is the best way to prevent pollution of the Thames from combined sewer overflows (CSO). He said the company should consider whether the project could also be made cheaper by omitting the section east of Battersea.
Binnie championed the Thames Tunnel in 2005 as Thames Tideway Strategy Steering Group chairman. But he told NCE that changes since then, including less water entering the sewers, sewage works improvements and the construction of the Lee Tunnel meant the Thames Tunnel could be shortened.
Stride said this was inaccurate. He said Binnie had not been involved in the project over the last five years and had not appreciated research done since 2005.
“Why didn’t he come to us and ask ‘what have you been doing over the last five years’?” Stride asked. He insisted that a shorter tunnel from Acton to Battersea in south west London had already been considered and dismissed because it would leave 17 CSOs unintercepted and would not meet dissolved oxygen targets, in breach of the Urban Wastewater Treatment Directive.
Septic sewage risk
Cutting the tunnel off at Battersea would, he added, also mean that sewage entering it during a storm would have to be pumped out through existing sewers, whose relatively low capacity would mean the process could take days.
This could lead to the sewage stuck in the tunnel becoming septic, creating odour problems, Stride said. If there was another storm before the tunnel was empty, sewer also flooding could occur he said.
The longer Thames Tunnel would connect through to Beckton Sewage Works in east London and avoid these problems, Stride said.