RODEO -- Hazardous materials crews pumped hundreds of thousands of gallons of "sour water" from a ruptured tank at a Phillips 66 petroleum refinery in Rodeo on Saturday as they continued to clean up from a leak the day before.
Health concerns were eased considerably by 3 p.m. Saturday, 18 hours after the tank released an unknown amount of hydrogen sulfide at the refinery located at 1380 San Pablo Ave.
Hydrogen sulfide is not dangerous in low concentrations, but its offensive rotten-egg smell is strong and easily noticed, and can cause dizziness and nausea, said Randy Sawyer, the county's chief environmental health and hazardous materials officer. It's presence in water makes it "sour," said hazardous materials specialist Paul Andrews.
Andrews called the leak a "pressure event," at the two tanks. Tanks are designed to have a weak spot at the top, and this one failed the way it was designed, he said.
The petroleum refinery, which Andrews said has existed for more than 100 years, makes gasoline, jet fuel and low sulfur diesel.
The threshold for the gas becoming a health hazard is 30 parts per million, and the highest measurement in the area surrounding the refinery was 1 part per million, recorded around noon Friday, Sawyer said. By Saturday afternoon, the levels fell to 4 to 6 parts per billion, with the higher readings in the upper levels of Crockett, said hazardous materials specialist Devra ¿Lewis.
Crews laid down a
The leak occurred about 7 a.m. Friday, when the tank ruptured. The cause of the rupture remains unknown, and the investigation likely won't be finished for weeks.
Rick Hurd and Chris DeBenedetti cover public safety. Contact Rick at 925-945-4780 and follow him on Twitter at Twitter.com/3rdERH. Contact Chris at 510-353-7011 and follow him on Twitter at Twitter.com/cdebenedetti