Lanes Utilities is removing a ten-tonne fatberg on behalf of Thames Water from a sewer under streets in West London.
The 50-metre-long fatberg was so heavy that it weakened the sewer to the point that it began to collapse when Lanes engineers tried to remove it.
Thames Water concluded the 70-year-old sewer had been damaged beyond repair and had to be replaced.
Lanes Utilities, part of Lanes Group Plc, is Thames Water’s wastewater maintenance and repair partner, and is coordinating work to remove the fatberg and install a new concrete sewer pipe.
Andy Brierley, Lanes Utilities Director, said: “This is an example of just what a scourge of sewer systems fatbergs are.
“They are made up of cooking oils, fats, disposable wipes and other materials that should not be put down the sewer.
“These congeal into a solid mass that result in problems like this. That’s why we fully support Thames Water’s campaign to urge customers to ‘Bin it – don’t block it’.”
The Chelsea fatberg, in the sewer under Draycott Avenue and Walton Street, weighed the equivalent of five Porsche 911 sports cars.
The only option was to remove the affected section of the egg-shaped sewer, which is 1100 mm high and 750 mm wide, with the fat still in it.
In places, Lanes Utilities’ civil engineering partner, Cappagh Browne, have had to dig down to the sewer using only hand tools to avoid disturbing a complex network of other utility pipes.
Conrad Ashby, Thames Water Framework Director for Lanes Utilities, said: “Managing these sewer rehabilitation projects is hugely costly and time-consuming.
“In this case, contingency plans have had to be put in place to divert sewer water through over-pumping. Traffic management has been introduced during the work, which is taking several weeks.
“These are all reasons why it would be so much better if service users could avoid contributing to the problem, through sensible disposal of their waste.”
Thames Water’s ‘Bin it – don’t block it’ campaign is aimed at reducing the number of fatberg and drain blockage problems across its service area, which takes in London, Thames Valley and parts of South West England.