Significant engineering challenges have been cited by Tideway as the driver behind the implementation of cost saving measures on the super sewer project.
Tideway made the statement in an interim report and financial statement for the six months to 30 September 2018 where it revealed that it has spent £325.3M over the last six months to bring the total project costs so far to £1.48bn.
The organisation said that it has now mobilised to 20 of its 21 construction sites as a result has identified several cost pressures in the programme.
In its report, Tideway said that the most significant of these engineering challenges is the diversion of two Victorian gas mains at Blackfriars; the cofferdam construction at King Edward Memorial Park, together with the associated programme prolongation at that site; cofferdam construction at Albert Embankment and various challenges at shafts across the east area sites.
“Taken together with general cost pressure across the programme this has substantially eroded available contingency,” said Tideway.
At Blackfriars, the report highlighted challenges caused by the proximity of the site to two large Victorian gas mains. It said to rectify the situation, Tideway was working closely with gas operator Cadent to investigate if the lines needed to be diverted to avoid damaging them. However, initial results from a damage assessment suggested that they may not require diversion, with final damage assessment results are expected by end of the year.
Meanwhile, at King Edward Memorial Park Foreshore cofferdam construction has taken longer than planned, due to unexpected ground conditions which required additional piles. It said this had resulted in the planned resequencing of works to alleviate the programme impact.
To mitigate the cost pressures Tideway has begun to implement cost saving measures in partnership with our contractors and remains focussed on achieving the baseline target.
“These cost saving measures include working with our main works contractors to eliminate overlap, taking measures to increase productivity, undertaking value engineering and delivering overhead savings.”
According to Tideway, it is too early to conclude the extent to which these measures will mitigate the cost pressures and an update is expected to be announced in the March 2019 Annual Report and Accounts.