50 tonnes of hardened grease removed from sewers in Richmond, B.C.

Metro Vancouver shared photos of the work on social media, along with a plea to keep fats, oils and grease out of the sewer system. (@MetroVancouver / X.com)

Crews removed approximately 50 tonnes of "fatbergs" from the sewer system in Richmond, B.C., earlier this month, according to Metro Vancouver.

The regional district shared pictures of the work on social media Thursday, along with a plea for people to put cooking oil, butter and grease in their green bins, rather than down the drain. 

"Fatbergs" are hardened chunks of grease that can build up in pipes and cause blockages. Metro Vancouver says on its website that fats, oils and grease harden in sewers "because of a chemical reaction that turns them into a concrete-like material." 

"Greasy foods mixed with soap still become part of that reaction," the regional district says.

In a statement to CTV News, Metro Vancouver explained that the Richmond photos were taken in mid-October as the fatbergs were removed from the Gilbert Trunk Sewer near Hollybridge Way and Lansdown Road in the city's north.

"Grease removal in this area has been ongoing since July, after more grease than usual arrived at Lulu Island Wastewater Treatment Plant in Richmond, including solid fatbergs," the district said in its statement.

"We used sonar technology to see inside pipes that cannot be inspected with traditional video equipment to find the problem areas within the sewer system. Crews have been working to break up and remove the significant buildup using high pressure water jetting and vacuum trucks. Work is done at night during low wastewater flow conditions."

As a region, Metro Vancouver and its constituent municipalities spend more than $3 million annually removing grease buildup from sewers. Most of that work is done during routine inspections, and the regional district described operations on the scale of the recent Richmond case as "uncommon."

"In this case, the accumulation was unusually extensive," the district said.

Asked whether fatbergs – in Richmond or elsewhere in the system – contributed to the flooding seen in parts of the Lower Mainland during last weekend's atmospheric river, Metro Vancouver said it has no evidence that grease contributed to sewer backups during the storm.

"The grease removal completed recently has restored capacity in those pipes, reducing the risk of backups upstream," the district said.

The regional district said preventing grease from entering the sewage system in the first place is "the best solution," noting that the region's Food Sector Grease Interceptor Bylaw requires commercial kitchens to maintain grease traps.

"To address grease issues in Richmond sewers, enforcement officers are increasing inspections to ensure compliance," Metro Vancouver said.

"We want to remind residents that fats, oils and grease from your kitchen can turn into fatbergs in the sewers, which can damage infrastructure and can cause backups into homes, businesses and the environment. Please keep fats, oils and grease out of the drain — use your green bin instead."