Materials

UK’s biggest ‘fatberg’ discovered in London sewer

sewer fatberg

Earlier this week (6 August), Britain’s ‘biggest ever fatberg’ was removed from drains under London Road in Kingston, Surrey.

The bus-sized lump of wrongly-flushed festering food fat mixed with wet wipes was discovered after residents in nearby flats complained that they couldn’t flush their toilets.

CCTV investigations in London Road found the mound of fat had reduced the 70 by 48 centimetre sewer to just five per cent of its normal capacity. According to Thames Water, had it not been removed it could have led to sewage flooding many homes, streets and businesses in the London suburb.

Gordon Hailwood, waste contracts supervisor for Thames Water, said: "While we've removed greater volumes of fat from under central London in the past, we've never seen a single, congealed lump of lard this big clogging our sewers before.

“Given we’ve got the biggest sewers and this is the biggest fatberg we’ve encountered, we reckon it has to be the biggest such berg in British history.

“The sewer was almost completely clogged with over 15 tonnes of fat. If we hadn’t discovered it in time, raw sewage could have started spurting out of manholes across the whole of Kingston.”

Thames Water began repairs to the 20 metres of damaged pipe on Monday (5 August), and work is expected to take ‘up to six weeks’ to complete.

Hailwood added: “Homes and businesses need to change their ways, when it comes to fat and wipes, please remember: ‘Bin it – don’t block it.’”

Traffic management will be in place and two lanes of London Road will be closed westbound between Coombe Road and Cambridge Road.

For updates on the repairs from Thames Water, subscribe to the ‘Text for Updates’ service by texting ‘Kingston’ to 80007.

‘Super sewer’ proposals

The UK’s population is served by around 200,000 miles of sewers, which regularly struggle to handle fats, oils and grease disposed of down domestic and commercial drains. London’s sewers, specifically, struggle to handle the problem and the sheer number of users: the Victorian sewer system, designed by Joseph Bazalgette when residents of the capital numbered two million, now has more than eight million users. The sewer’s 57 overflow points annually deposit 16 million tonnes of waste into the Thames.

The contentious solution put forward by Thames Water is to build a 20-mile long ‘super sewer’ to collect 39 million tonnes of sewage a year from the 34 worst overflow points. The Thames Tideway Tunnel is expected to cost more than £4 billion, and is facing opposition from residents near the proposed construction sites, who are angered by the prospect of three years of building works.

Thames Water provides sewer fat for power station

As a part solution to the problem of fat going down drains, in April this year, Thames Water signed a £200 million, 20 year deal with green utility company 2OC, to provide ‘at least half of the fuel’ needed to power ‘the world’s largest fat-fuelled power station’ in Beckton, East London.

The combined heat and power plant (CHP) is set to produce 130 gigawatt hours (GWh) a year of renewable electricity, enough to run 39,000 average-sized homes.

From 2015, Thames Water will collect 'clean' fat, sourced from restaurants and drains before it hits the sewers. This includes ‘solidified grease’ (such as that from lamb and chicken) from ‘fat traps’ in restaurant kitchens and ‘leftover, low-grade cooking oil and food fat’ from food outlets and manufacturers, which will form half of the CHP plant’s required daily fuel allowance – around 30 tonnes of fat, oil and grease per day.

Read more about the UK’s sewage system.