Bazalgette Finance, the group of investors funding the project, say that tunnelling has been delayed by the Covid-19 lockdown and requirements for reorganising working practices.
“The company's latest modelling indicates construction work, which was due to be completed in 2024 (the project 'handover' date), is now likely to be completed in the first half of 2025, adding nine months to its current schedule,” it disclosed.
The revised completion date adds £233m to the previous budget forecast, taking the estimated project cost to £4.133bn.
It added: “Tideway is in discussions with Ofwat on a package of measures that would mitigate the financial impact of COVID-19 on the company. We are making progress in these discussions and we expect to reach a full agreement in the coming months.”
Explaining the impact of the virus on the project, it said: “Following a temporary pause of all but essential works at the start of the UK lockdown, construction work recommenced on the majority of the company's worksites in May, albeit at a lower level of activity in order to comply with social distancing requirements.”