An independent consultant has admitted his 2006 evidence supporting the need for the Thames Tunnel may now be out of date.
Chris Binnie this week submitted documents to Lord Selborne's Thames Tunnel Commission (TTC), calling for new research to be carried out.
Mr Binnie was chairman of the Thames Tideway Strategic Study Group (TTSSG) between 2000-2006. At the time, he reported the tunnel would be the most effective and cost-efficient way of reducing the amount of waste that flows into the river.
But at a commission hearing last week, Lord Selborne informed the Department for Environment, Food and Rural Affairs (DEFRA) that Mr Binnie had now stated the TTSSG's recommendations might need revisiting.
Commissioner Henry Henderson told DEFRA that Mr Binnie had accepted that there had been a limited review of alternative options to the Thames Tunnel, with £12,000 spent on researching sustainable urban drainage solutions and £5m spent on researching the Thames Tunnel.
Mr Binnie's written evidence to the Commission suggests that a much shorter tunnel, when working in tandem with the recently-built Lee Tunnel, could be an effective solution to meeting EU requirement, stating: "There are a number of features that would be worth looking at as to see how viable a two tunnel scheme might be, thus postponing substantial capital expenditure on the whole Thames Tunnel."
The TTC is due to report its findings at the end of October.