A sewage worker has become an unlikely hero after taking three weeks to defeat a toxic 15-tonne ball of congealed fat the size of a bus that came close to turning parts of the London borough of Kingston upon Thames into a cesspit.
The first sign of trouble came when residents in a block of flats near the royal borough’s main sewer reported difficulty flushing their toilets. Gordon Hailwood and his team found a “fatberg” of solidified grease and oil blocking 95 percent of the 2.4m-diameter brick sewer pipe. It took three weeks to clear with high-powered water jets.
“Kingston came very close to being flooded with sewage. We have recorded greater volumes of fat in the past, but we don’t believe there’s ever been a single congealed lump of lard matching this one,” said Simon Evans, a Thames Water spokesman.
Fatbergs build up on sewer roofs like mushy stalactites.
“I have witnessed one. It’s a heaving, sick-smelling, rotting mass of filth and feces. It hits the back of your throat, it’s gross,” Evans said. “It’s steaming and it unleashes an unimaginable stink. Hailwood and his team certainly saved Kingston from a terrible fate.”
Water and sewage companies say fatbergs are becoming more common. London, with the highest concentration of food businesses in the country, produces an estimated 32 million to 44 million liters of used cooking oil every year, much of which is poured down drains.
Also, the use of wet wipes as toilet paper is increasing, with potentially disastrous results below ground.
Thames Water says it has to clear nearly 40,000 blockages a year caused by fat and sanitary wipes being wrongly put down drains by restaurants and households.
“We have 59,000 miles [94,951km] of sewer, and fat and wet wipes are the main partners in ‘sewer abuse’ crime,” Evans said.
“The wipes break down and collect on joints and then the fat congeals. Then more fat builds up. It’s getting worse. More wet wipes are being used and flushed. It took Hailwood and the guys three weeks to flush this one out with high-powered water jets.
“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,” Hailwood said.
“The sewer was almost completely clogged. If we hadn’t discovered it in time, raw sewage could have started spurting out of manholes across the whole of Kingston. It was so big it damaged the sewer and repairs will take up to six weeks,” he added.
However — in what environmental groups call a “win-win” development — waste fat is now being used to generate renewable energy. McDonald’s collects more than 600,000 liters of used cooking oil from its London restaurants each year, converting it to biodiesel to run half its fleet of lorries. London Mayor Boris Johnson is pressing for waste fat to be used to run London’s buses.
“By capturing it here in London and turning it into biodiesel, we could provide 20 percent of the fuel needed to power London’s bus fleet,” Johnson said last week.