Authorities evacuated more than 200 people from their homes in this San Francisco suburb Wednesday night and prepared to destroy several gas canisters suspected of containing the same lethal mixture that killed three people last week in New Jersey.
"It's a big task, but it's going very smoothly," San Carlos Police Chief Owen McGuigan said of the evacuation. "The residents are being very cooperative."
As McGuigan spoke from an emergency command center set up in City Hall, 21 law enforcement agencies and 12 fire departments prepared to escort trucks carrying about 30 canisters from an industrial yard here to a disposal site two miles away.
There, on salt flats next to the San Francisco Bay, the canisters were to be detonated by military charge late Wednesday or early today, "if everything goes according to schedule . . . ," McGuigan said.
Police and fire officials were seeking to end three days of tension at the Liquid Carbonics Specialty Gas Corp. plant here. The plant and about 20 nearby businesses have been closed since Saturday in the wake of an explosion in New Jersey last Thursday.
In that incident, a canister of silane gas contaminated with nitrous oxide blew up and killed three workers and injured a fourth at Gollub Analytical Services in Berkeley Heights, N.J. The cylinder was filled at the San Carlos plant. Liquid Carbonics sent a team of experts to the plant here to check silane canisters with similar markings.
But the team never determined if the canisters contained the same lethal mixture seen in New Jersey. That would have taken lengthy and potentially dangerous testing. Instead, a plan was devised to transport and destroy all the canisters suspected of being contaminated.
The San Carlos Police Department placed its officers on alert and called in all reserve officers. The South County Fire Authority, which includes San Carlos and neighboring Belmont, called in its off-duty firefighters as a precaution.
Since Monday, tanker trucks rumbling in and out of the plant here have removed more than 25,000 gallons of liquid oxygen, nitrogen, hydrogen and other chemicals that could explode if they come into contact with any contaminated canisters. Officials also trucked in more than 1,000 sandbags to serve as a barrier against an explosion.
On Monday, more than 800 workers at Teledyne Semiconductor Co. in Mountain View and Advanced Micro Devices in Sunnyvale were sent home while experts checked and removed two cylinders of the potentially explosive gas from each site. Those cylinders were later destroyed, and employees were back on the job Tuesday.
A portion of U.S. 101 was expected to be closed for about 45 minutes Wednesday night while the canisters were being taken to the nearby salt flat. Authorities said the canisters would be submerged in water-filled trenches and punctured. Once the gas rose through the water, it would dissolve harmlessly in the air, they said.
The New Jersey attorney general's office is investigating last week's explosion. A spokesman said Wednesday that no clear explanation for the cylinder's contamination has yet emerged. Liquid Carbonics officials were unavailable for comment Wednesday.
Silane gas is widely used in the semiconductor industry to process wafers for integrated circuits. It is explosive when combined with oxygen, nitrogen oxide or other gases.
Griffin reported from San Carlos and Arax reported from Los Angeles; Times researcher Norma Kaufman contributed to this story.