A planned "special operation" flare up at a refinery in Martinez caused concern for surrounding residents Friday evening.
Those near 3485 Pacheco Blvd reported seeing a fire and hearing an explosion around 5 p.m., firefighters said.
A Contra Costa Fire Protection District spokesperson said firefighters responded to reports of a fire or explosion at the Martinez Refinery Company late Friday afternoon, but later cancelled its emergency response because the large flames that were seen in the area were a result of the flare-up.
Refinery officials confirm the flare-up -- conducted to burn off deposits -- was part of an ongoing special operation. The operation, including the fire, was confined to refinery property.
The refinery has come under recent scrutiny when Contra Costa County health officials said it did not notify them of a possibly harmful 12-hour release of chemicals that started on the evening of Thanksgiving two weeks ago.
State law and county policy requires MRC to report chemical discharges to CCH within 15 minutes. Health officials said they only found out about the chemical discharges release through social media posts and when they contacted the refinery a day-and-a-half after it started.
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Following that, Martinez residents found a powdery substance on their cars and around the community the day after Thanksgiving. Samples later taken by CCH showed the "spent catalyst" substance contained higher-than-normal amounts of heavy metals such as aluminum, barium, chromium, nickel, vanadium, and zinc.
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Bay City News contributed to the report.