Experts welcome second investigation into London's super sewer

Francesca Washtell
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A sewer technician in a sewage tunnel at the Abbey Mills pumping station in London

London is in desperate need of new sewage capacity, according to experts, who welcomed a second investigation into the Thames Tideway “super sewer” on transparency grounds.

The National Audit Office (NAO) has said it will publish a second study into the £4.2bn infrastructure project in the autumn, when construction on the 25km Thames Tideway Tunnel is due to start.

“There’s no doubt that London needs more sewage capacity, which we’re currently exceeding,” said Dan Lewis, senior adviser on infrastructure policy at the Institute of Directors.

“We welcome the transparency the investigation will bring. When you have big projects like these it is important to have as many people look at it as possible. The powers that be have said a second one is necessary, let’s see what it says.”

Read more: Thames Tideway Tunnel: Digging deep to avoid the next big stink

The NAO has said it will examine the choice of the Thames Tideway Tunnel over alternative options, as well as exploring the risks posed to customers and taxpayers.

The super sewer will be delivered by a licensed infrastructure provider, Tideway, which is owned by a consortium of investors and pension funds, and includes delivery partners such as Thames Water.

Construction is scheduled to be completed by 2022.

"The Thames Tideway Tunnel was chosen as the only way of dealing with the problem of sewage capacity in the timescale required," a spokesperson for Tideway told City A.M.

“Ofwat, Thames Water and the government have all agreed that having this infrastructure provider delivery model was the best way of keeping the costs down for customers."

Read more: We flush out the myths about London's sewers

Historically, the cost burden to Thames Water customers was expected to be an extra £70 to £80 per year.

However, the delivery model the company has opted for has slashed that cost to between £20 to £25 per customer each year, which will be paid for the "foreseeable future".

Tideway also told City A.M. that risks the tunnel has been rumoured to pose, such as damaging the foundations to Big Ben or flooding the London Underground, are ill-founded.

"We are totally confident it poses no threat to Big Ben or to flooding the tube given the depth we will be tunnelling at," Tideway's spokesperson said.

A spokesperson for the NAO said the new study is “likely to be a routine follow-up investigation” to its 2014 early review.

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