Alarms at the plant, 3900 Holly Drive, began sounding shortly after 11 a.m. when a leak occurred during the unloading of sulfur dioxide from a tractor trailer and into a storage area at the plant, according to David Bramell, division chief with the Tracy Fire Department.
“It was isolated to this one area where that product is stored,” he said. “It was a small leak that gave us some readings that are dangerous if you are working in that area. But the general public was never really in any danger.”
Sensors in the storage area detected levels of sulfur dioxide vapor or liquid at 10 parts per million, which exceeds the standard of 0.5 parts per million, Bramell said.
Sulfur dioxide is one of several chemicals used to treat wastewater at the plant.
When high levels are detected, an internal system at the plant will begin to scrub the air and the area of any excess chemicals until the levels descend to safe levels again, according to Kevin Tobeck, director of public works for Tracy.
About 30 employees were evacuated as part of the plant’s preparedness plan, Tobeck said.
“The system worked as intended,” he said. “We evacuate any time this happens, because it’s better to be safe than to be sorry.”
Tobeck said the excess chemicals were pumped into an on-site emergency pond. He said that the city “doesn’t foresee any impact to any of the users and the services.”
Employees at businesses near the plant were told to shelter in place while the threat was initially assessed, Bramell said. No injuries were reported.
Fire crews remained at the scene for nearly three hours before plant employees were allowed to return to work.
Hazmat technicians from the Tracy, Lathrop, Manteca and Escalon fire departments were sent into the plant to secure open valves on the tractor trailer and inside the plant, and to make a final conformation that the leak was contained.
The technicians are part of the San Joaquin County Joint Hazmat Team. Bramell said a team of eight to 10 technicians is needed any time a chemical spill is reported in the county.
“Chemical spills have a real potential to be dangerous, so you need the right people who are certified to handle these things,” he said. “You never want to rush into the situation, because you don’t know what’s happening. So we slow things down and take a methodical approach for everyone’s safety.”
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