A HIGH profile water engineer this week condemned the £2bn Thames Tideaway Sewage Tunnel as a white elephant and urged Thames Water to consider alternatives to the scheme.
Sheffield University professor of urban drainage Richard Ashley told the ICE's evidential hearing on climate change that 'the Thames Water sewage tunnel is the biggest white elephant.' He later told NCE that the project would be 'repeating what Bazalgette did years ago' when he built the stormwater sewers under London's Victoria Embankment.
'They're building the tunnel because the system can't cope with the levels of storm water and of course they'll go and build a desalination plant because of water shortages. There is no joined up thinking, ' he said.
Water regulator Ofwat has already expressed concern over the 32km, 7.2m diameter stormwater tunnel which will run under the route of the Thames from west to east London, which it thinks could cost much more than expected. At depths as low as 80m engineers told NCE it would push the limits of tunnelling experience.
Environment Minister Ian Pearson gave Thames Water the go ahead to develop the scheme in March.
Thames Water chief executive David Owens defended the project.
'The tunnel will be longer than many London Underground lines, and will have to be built at great depths, up to 80m beneath the Thames, ' he said.
'However, this is work which needs to be done. It will have long-term environmental benefits for the Thames and for the health of people who use it.
'Together with the £400M of investment we have planned for upgrading our sewage treatment works at Beckton, Crossness, Mogden, Longreach and Riverside, it will help protect the aquatic environment and provide the city with a sewerage system fit for the 21st Century and beyond'.
But Ashley said Thames Water was being pushed into building the scheme so it could meet European Union (EU) regulations. 'Of course they'll be happy because they've got themselves a £2bn asset but it's not really their fault.' He explained that the UK is already in breach of the EU Urban Waste Water Treatment Directive in an number of locations, including London for allowing too much untreated waste to flow into rivers because its sewers are unable to cope with storms.
One senior industry figure who did not want to be named sympathised with Ashley's view but said there was little else Thames Water could do. 'It is hard to see a real alternative, I don't disagree in the general sense with what he is saying but what else could you do?' He added that Ashley's suggestion to retrofit storm water management systems but the senior figure claimed was unfeasible, pointing out: 'it's simply not possible to tackle the problem at that end. Capacity couldn't be sufficiently increased at sewage plants to cope with that volume of water, nor would it be realistically possible to store it to process later.
'The question that should be asked is: 'Is this project value for money?' If the answer is no then it should be left to the government to make the case to the EU that London is in exceptional situation and should be exempt from the directive, just as Italy and France have done, ' he explained.
'Ofwat is anxious about the risk of this project. It goes beyond the edge of tunnelling knowledge and their real fear is that this £2bn piece of infrastructure is really going to cost £10bn, ' said the senior figure.
Beginning at the Chiswick shaft in west London, the 7.2m diameter tunnel will pick up storm water through London discharging at Beckton in the east.
At the moment some 20Mm 3 of storm water is discharged annually into the Thames creating an environmental hazard.