Bad Smell at refinery causes 4-hour 'shelter in place' order in Crockett

The release also set in motion Contra Costa County's automatic telephone dialing system, county and refinery officials said.

Officials of the refinery, the county hazardous materials division and the Rodeo-Hercules Fire Protection District said the release, which began around 4 a.m., did not endanger human health.

Refinery spokesman Bill Tanner said crews working on a gas line accidentally vented some excess natural gas that was mixed with hydrogen sulfide, a gas that gives off a telltale rotten egg smell.

County hazardous materials specialist Paul Andrews said the first call to the county came in at 4:08 a.m. Sirens sounded about 4:20 a.m. and officials activated the telephone warning system about 4:30 a.m., Andrews said. The system dialed residents in Rodeo, Tormey and Crockett. Andrews could not immediately say how many people were reached.

The pipeline that leaked today was part of a loop that normally directs excess gases to a flare, Andrews said. Workers capped the line at 6:15 a.m. and the "all clear" was announced shortly afterward.

The odoriferous gases that triggered the shelter-in-place order included hydrogen sulfide and other reduced-sulfur gases known as mercaptans, Andrews said.

The odors of the gases are strong enough to cause headaches or nausea, Andrews said.

An air inversion at the time of the leak prevented the gases from dispersing, Andrews said.

"Warm air close to the ground and cold air aloft pushed everything down, and there was very little wind," Andrews said. The smell primarily affected Tormey and Crockett, Andrews said.

Tanner said the incident is under investigation.

"We're very sorry to have created this situation," said Tanner, who praised fire district, county hazardous materials and Bay Area Air Quality management District crews for the quickness and efficiency of their responses.

"We work very hard to ensure that we don't have an impact on the community, and we didn't do a good job this time," Tanner said. "We'll investigate and put procedures in place to make sure it doesn't happen in the future."