Making Unique Observations in a Very Cluttered World

Friday, 9 August 2013

London has 'fatbergs' but Vancouver has gross 'F.O.G' blobs - Fats, oil and grease -

London has 'fatbergs' but Vancouver has gross 'F.O.G' blobs - Fats, oil and grease - 

Manhole outside local restaurant  filled with grease.

Forget alligators, the real problem in sewers is ‘fatbergs’ — such as the monster blob of congealed fat and baby wipes that recently clogged a London sewer.

That beastly blockage weighed an astounding 15 tonnes.

Metro Vancouver may not yet have had a ‘fatberg’ like that but Mike Boss, a senior engineer in maintenance and operations at the regional district, said there is ongoing battle with what is more commonly known as FOG — fats, oils and grease.

“It’s a problem all over the world,” said Boss.

The worst accumulation he’s ever seen was in a 106 centimetre Metro sewer in Richmond where a remote controlled vehicle was stopped because of the FOG on the ceiling and walls of the pipe, which is where the water-borne fat congeals.

“It probably extended about 10 metres or so,” said Boss of the Richmond blob,

Pressurized and heated water is used to remove FOG.

“It takes a lot of back and forth to get it all out,” he said. “It doesn’t come out easily. It gets very hard.

“It’s not like a gooey fat. They almost need to chip away at it.”

The cost to Metro and its taxpayers for FOG is about $2 million annually.

But it could be worse.

A municipal sewer pipe in Richmond was so blocked it had to be removed to deal with the blockage.

Flushing oil and grease is against Metro bylaws, which require commercial users like restaurants to have grease traps that have to be pumped out regularly.

The waste from those traps can be sent to a Metro facility that makes biogas that is used to create energy.

Metro even has a film about grease in sewers, which can be found online — if you dare to watch it — at http://bit.ly/19QF70T.

Like Metro, the city of Vancouver also requires private grease traps and monitors those traps, according to Peter Judd, general manager of engineering services.

“The concern is addressed through our regular maintenance and flushing program of the sewer system and is also helped by parts of our sewer having fairly steep grades, which keep flow velocities high, inhibiting buildup of material in those areas,” said Judd in an email.

There’s also a lot more to worry about than FOG blobs, said Boss.

The most unusual thing he’s ever heard of being removed from a sewer pipe was a sleeping bag and a pair of jeans — which Boss thinks must have been dumped down a manhole.

But the many things people flush down toilets that they shouldn’t also create problems.

Boss said those objects include wipes, condoms, tampons and needles, all of which block pumps and need to be removed manually.

“People have to wear chain mail gloves and pull that stuff out,” said Boss. “It’s a safety risk for our staff.”

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