Specialists in blocked drains and plumbing repairs

London sewers saved from 15 tonne ball of grease

A team of sewerage workers took three weeks to clear bus-sized toxic ball of fat that threatened to flood streets with sewage.

A london sewer 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.

London Sewer Grease Ball

Residents in a block of flats near the royal borough’s main sewer reported difficulty flushing their toilets, which was the first sign of the problem. Gordon Hailwood and his team found a “fatberg” of solidified grease and oil CCTV investigations in London Road found the mound had reduced the sewer to just five per cent of its 2.4 metre diameter brick sewer pipe. It took three weeks working in foul conditions to clear with high powered water jets.

Simon Evans, a Thames Water spokesman, said: “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.”

Fatbergs build up on sewer roofs like mushy stalactites. “I have witnessed one. It’s a heaving, sick-smelling, rotting mass of filth and faeces. It hits the back of your throat, it’s gross,” said Evans. He continued, “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 32m-44m litres 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 of sewer and fat and wet wipes are the main partners in ‘sewer abuse’ crime,” said Evans.

“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. 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” said Hailwood.

However – in what environmental groups call a “win-win” development – waste fat is now being used to generate renewable energy and McDonald’s collects more than 600,000 litres 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 right here in London and turning it into biodiesel we could provide 20% of the fuel needed to power London’s entire bus fleet while saving thousands of tonnes of CO2 and creating hundreds of new jobs. There is huge potential to unlock the value in used cooking oil and turn it to our economic advantage,” Johnson said.

What is blocking our drains?

  • Animal fats and vegetable oil, lard, grease, butter and margarine, food scraps and dairy products all contribute to blocked drains, “fatbergs” and sewer blockages. Waste disposal units do not remove fats.
  • Wipes, nappies, sanitary towels, rags and condoms do not break down easily and can snag on pipes, drains and the walls of sewers, leading to blockages.
  • Pesticides, battery acids, nail polish, motor oil, chlorine-based and other cleaning products, paints and photographic chemicals are all toxic waste and should be disposed of carefully because they do not break down in sewage systems and can pollute rivers and sea water.
  • If you have a septic tank, then be extra careful. Don’t flush medicines, coffee grounds, paper towels or egg shells, or anything that breaks down slowly, down the toilet or sink.

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