Sour gas release brings work to a halt
MILDRED LAKE — Two workers sustained minor injuries while evacuating an oil sands operation in northern Alberta following an unplanned release of sour gas.
At about 12:35 pm on July 9, there was a release of hydrogen sulphide (H2S) and ammonia at Syncrude Canada Ltd.’s plant near Fort McMurray, says Barrie Harrison, a spokesperson for Alberta Employment and Immigration (AEI) in Edmonton. The release occurred as a result of a weld failure on the C-4 overhead drum, which holds the aforementioned chemicals, Harrison reports.
Cheryl Robb, a spokesperson for Syncrude Canada, says that when the H2S was released, alarms were activated and the unit evacuated.
AEI issued a stop-work order, which was later lifted. Harrison adds, however, that the plant was to remain out of commission while Syncrude Canada carried out an assessment and made any necessary repairs.
The H2S and ammonia were released when sour water waste leaked from the plant. Robb explains that the sour water is produced by the separation of nitrogen and sulphur from the bitumen.
A material safety data sheet for H2S notes that it is a toxic, flammable gas that poses an immediate fire hazard when mixed with air. Ammonia, for its part, can lead to pulmonary edema or chemical pneumonitis when inhaled.
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