Assembly members are also worried about the complexity of the planning process as it requires permission from several London boroughs.
Despite these concerns, the Assembly’s health and public services committee said in its response to the consultation process that it fully supports the project concept and agrees that it is the best solution to reduce the amount of untreated sewage flowing into the river Thames. When London’s sewer system becomes overloaded from rainfall, overflows of sewage and rainwater discharge into the river. Thames Water’s solution is to build an interceptor tunnel underneath the river so that any overflow from the sewers can instead be transported to the treatment works at Beckton in east London.
James Cleverly, chair of the Assembly’s health and public services committee, said: “Every year, 39 million tonnes of untreated sewage is discharged into the River Thames from London’s sewers – enough to fill the Albert Hall 450 times over. There is widespread consensus that this problem is getting worse and we believe the Thames Tunnel offers the best solution.
“However, there are a number of concerns that need to be addressed by Thames Water and its partners and we look forward to receiving further details of the scheme in the future.”
The committee is concerned that the full cost of the tunnel to Londoners is not yet known. Thames Water has estimated that customers will face an additional charge of £60-£65 per year, but has not said for how many years these charges will last.
The committee also said that the government should consider how the Mayor of London could co-ordinate the planning process for the tunnel proposal instead of it having to go through multiple planning applications in different boroughs.