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Post-flood dangers may include naturally-occurring asbestos

Contractors working on post-flood cleanup and rebuilding have another thing to watch closely.

B.C. contractors who are working in areas where flooding has occurred may need to carry out a site risk assessment to determine if there are residual effects of contaminates, including exposure to naturally occurring asbestos (NOA), as is known to occur in the Sumas River area.

“WorkSafeBC advises there may be widespread contamination, including potential problems with naturally-occurring or materials-related asbestos, on almost any worksite where flooding has occurred,” spokesperson David Karn for the Ministry of Environment (MOE) said via email.

“For information about requirements for employers to conduct work site risk assessments, please contact WorkSafeBC.”

The Sumas River has long been known to carry NOA and has been noted in both news and B.C. government reports while Abbotsford has conducted dredging of the river in its area to remove and dispose of the NOA in past years.

The Sumas River’s NOA derives from a decades-old U.S. landside on Sumas Mountain in Washington State (WA) where rock has released NOA fibres. The mountain has continued to erode and sediment accumulation travels north via Swift Creek, a tributary of the Sumas River which flows into B.C.

The United States Environmental Protection Agency (US EPA) studied the effects of common activities for individuals who live or work near the U.S. based Sumas Mountain and flood areas along Swift Creek. The US EPA found exposure may occur through the inhalation of airborne asbestos during activities that disturb sediment deposits on banks. NOA fibres can be released in wind, foot or vehicle traffic.

In November 2021, both Abbotsford’s and the U.S. Whatcom County’s Sumas areas experienced massive flooding.

Whatcom County health officials at that time on the U.S. side issued a warning to Sumas, Everson and Nooksak residents regarding the potential for NOA to be carried onto land by the water.

U.S. health authorities warned anyone cleaning up flood debris should wear a respirator rather than a COVID-19 face mask, footwear could contain fibres, and land and equipment that encountered NOA in water could contain the fibres once dried off and the fibres disturbed.

B.C.’s MOE has issued a statement that said a multi-agency provincial task force on flooding had conducted a one-time surface water and sediment sample program of flood-impacted water bodies in the Sumas Prairie which included analysis for NOA. Once completed assessment results are posted on the ministry’s government website.

The B.C. Ministry of Agriculture, Food and Fisheries has also worked with producers to do an early survey of soil. Testing and analytical results thus far have not revealed contamination.

“More testing will take place,” the MOE statement said.

A 2018 B.C. cross-ministry report, Keeping Workers, the Public and the Environment Safe from Asbestos, said: “An example of where British Columbians may be exposed to NOA is from sediments in the Sumas River, near Abbotsford.”

Sediment in the Sumas River contains NOA13, according to the report at that time. Storm events were expected to increase, which can cause flooding and increased movement of the sediment. The report said “contaminated sediment continues to accumulate on the Canadian side of the border and repeated flooding events exasperate the issue.”

The Sumas River has been dredged on two occasions to remove the NOA soil that flows down from the U.S.

The City of Abbotsford incurred dredging costs of $125,000 in 2010 and $52,000 in 2011 due to the additional safety requirements associated with handling and disposing of the dredged sediment.

In 2019, the Vancouver Sun covered a story on NOA occurring in B.C.’s Sumas River area citing fears asbestos-laced sediment deposited on the banks of the Sumas River could be stirred up by the wind or human activity and be inhaled.

B.C. also has its own sources of NOA. Most of B.C.’s deposits occur along a belt trending from the U.S. border near Hope to the Yukon border north of Dease Lake, between the Coast Mountains and the Rockies.

Jean Sorensen is a B.C. journalist who has written for business and legal publications over a span of 50 years. She specializes in business, technology, and law and her articles have appeared in national publications such as the Financial Post, forestry publications, and the Journal of Commerce. She was one of the first women in Canada to hold an executive position on a timber journal and visit camps logging camps throughout B.C.