BACKERS OF Thames Water's £2bn Thames Tideway Sewage Tunnel this week hit back at claims that the scheme is a white elephant and should be scrapped.
Last week Shefeld University professor of urban drainage Richard Ashley told the ICE's evidential hearing on climate change that there had to be better alternatives to dealing with stormwater overow than building a 32km long, 7.2m diameter tunnel (News last week).
But former chairman of the Thames Tideway Strategy Steering Group, Chris Binnie, this week insisted that all options had been considered as part of a ve year, £4M study that concluded the tunnel was the least cost solution.
Binnie dismissed Ashley's suggestion of retrotting storm water management systems, adding that separating London's combined sewer system by installing a second pipe system would cost £12bn.
Binnie said SUDS in ltration systems had also been ruled out because most of London is underlain by impermeable London clay and that there were insuf cient sites for ood detention ponds. He added that putting screens on the current combined sewage overows would do little to reduce dissolved oxygen levels.
'Yes the scheme is large and expensive, ' said Binnie. 'But any scheme which will be used on a weekly basis, will protect the River Thames through London from about weekly sewage over flows, and allows the UK to avoid large fines for breaching a European Directive can hardly be described as unnecessary.' See Viewpoint page 15