Gasoline Tank Explodes in Flames at Long Beach Plant : Blast: Fire rises 100 feet into the air but no one is injured. Health officials try to assess effect of thousands of gallons of contaminated water flowing into storm drain.

Flames shot more than 100 feet into the air after a gasoline tank at a Long Beach gas processing plant exploded early Monday morning, but firefighters had the blaze under control within hours and there were no injuries.

The fire started shortly after midnight at the Petrolane Co. plant, which processes natural gas for sale primarily to the Long Beach Gas Department, officials said. Investigators had not determined the cause of the fire.

More than 100 firefighters worked through the night and extinguished the blaze by 7 a.m., said Long Beach Fire Department spokesman Robert A. Caldon.

The 20,000-gallon tank contained unrefined gasoline, a byproduct of natural gas processing, that would have been shipped to an area refinery, said plant spokesman Mark Shemaria. There were no evacuations and fumes from the blaze apparently did not cause any health problems, Caldon said. The plant at 2901 Orange Ave. is in an industrial area, near Signal Hill and its oil fields.

Long Beach health officials were trying to assess the effect of the thousands of gallons of contaminated water from fire hoses that mixed with fire retardant and gasoline and entered a nearby storm drain.

The tank that caught fire and seven others were surrounded by a five-foot-high berm designed to contain spills. But the water from firefighters’ hoses filled the containment area, which overflowed and washed away a portion of the berm, Caldon said.

The storm drain caught the tainted water and channeled it to a collection basin, which has automatic pumps that started sending water down another storm drain toward the Los Angeles River and the ocean. Some tainted water apparently escaped before city workers could shut down the pumps, Caldon said.

“We still don’t know if it went just a way down the storm drain or all the way to the L.A. River,” Caldon said.

Petrolane hired a contractor to begin pumping out tainted water, Caldon said.

Petrolane shut down production, but officials expected the plant to resume operations later in the week.

The explosion and fire were small when compared to the blast and flames that ravaged Texaco’s Wilmington refinery Oct. 8. The Texaco explosion was felt miles away and forced the evacuation of about 600 people from nearby neighborhoods.

Investigations by Texaco and state authorities are continuing, said company spokesman Norm Stanley.

Rick Rice, a spokesman for the California Department of Industrial Relations, which is leading the investigation, said he expected the agency to complete its work in two to four weeks. He said investigators are awaiting test results on the damaged parts of the refinery.

The explosion occurred in a hydrocracking and a hydrogen generation unit, which are used in the superheated process of refining oil into gas.

Repairs are under way at the refinery, Stanley said, but it has resumed limited operations. Its output is close to 35,000 barrels of gasoline a day compared to 50,000 before the explosion, Stanley said.

Times staff writer Randal C. Archibold contributed to this story.