The Bacteria That Ate the Toxic Dump Site : Environment: Unocal’s old storage facility was sold for development but was too tainted to use. Enter bio-remediation, where microbes clean soil by dining on toxins polluting it.

An expanse of bare ground dotted with yellow bulldozers, the 45-acre tract at Crenshaw and Lomita boulevards in Torrance looks like any other large piece of property being readied for development.

But the land, a former Unocal oil storage area slated to become a shopping center and light-industrial park, holds a special distinction. It took California’s largest bio-remediation project to make it fit for development.

Bio-remediation is a cleanup method that uses bacteria to consume pollutants. In the $13.5-million Unocal project, completed last month, microbes already in the ground were nurtured to multiply and cleanse 300,000 cubic yards of oil-tainted soil--the equivalent of 15,000 dump trucks-full.

The work comes amid a sharp increase in California in the use of bio-remediation to prepare polluted industrial sites for new development, said Jim Ross, a senior engineer with the state Regional Water Quality Control Board. None has approached the size of the Torrance project, he said.

“That’s the granddaddy of all bio-remediation projects,” Ross said. “Typically, the average project is under 10,000 cubic yards.”

The Torrance work was performed as part of an agreement under which Unocal sold its former oil storage site in 1989 to Torrance Crenshaw Properties, a development partnership.

The partnership’s plans, approved by the City Council on April 2, call for a 356,104-square-foot shopping center to be named Torrance Crossroads and a 13-acre light-industrial park.

The oil company agreed to clean up soil contaminated with bunker oil, a dense ship fuel stored on the site until 1973. According to Ross, water quality officials would not have allowed development without a cleanup because the pollution threatened to enter the ground-water table.

Officials with Unocal and Ecova, a Seattle firm that was Unocal’s consultant for the Torrance project, acknowledge that bio-remediation generally takes longer than the most common method of dealing with polluted soil: digging up tainted earth and removing it. But they cite two key reasons--cost and potential legal liability--for resorting to bio-remediation.

The bio-remediation bill was $45 per cubic yard. Sending polluted soil to a landfill, they said, generally costs from $60 to $300 per cubic yard--potentially a huge price tag considering that 300,000 cubic yards were involved.

The closest hazardous-waste facilities that might accept such soil are in Kettleman--70 miles northwest of Bakersfield--and Utah, said Gary Armstrong, a solid waste expert with the Los Angeles County Sanitation Districts.

“It’s very possible that even these sites couldn’t take the material,” said Armstrong, who was not involved in the Unocal project. “Then you’re talking about transporting it even farther, probably to Texas or Arkansas.”

The second reason bio-remediation was chosen, Unocal and Ecova officials said, is that sending polluted soil to a landfill could have exposed them to legal liability.

Ross and Armstrong agreed. If cleanup is required at a hazardous-waste landfill, they said, companies that have sent waste to the facility can be forced to help pay for the work.

“It doesn’t matter that you don’t do anything illegally when you throw it away,” Armstrong said. “Any time you ship hazardous waste to a landfill, you have that liability hanging over your head.”

The bio-remediation at the former Unocal property began in January, 1989, and ended last month, according to Bob Schrag, the Unocal official who supervised the project.

Polluted soil was piled on a 27-acre section of the site, then treated and placed elsewhere on the property, 18-inch layers at a time. The treatment involved regular grooming and doses of phosphorous, nitrogen and water to stimulate the growth of bacteria in the soil that consume hydrocarbons.

As a result, Ecova Vice President John Cioffi said, the bacteria grew from 100- to 10,000-fold in number, all the while munching hydrocarbons and emitting harmless carbon dioxide.

“The soil in your front yard has these microbes,” Ross said. “They love hydrocarbons. It’s like a candy lunch. Without those key ingredients like nutrients and oxygen, it’s an incredibly slow process, but if you enhance it, it can do a massive job.”

According Ross, the treatments lowered oil contamination in the soil from average concentrations of 50,000 to 100,000 parts per million to a level of 1,000 parts per million, which is acceptable to the water quality agency.

Ross said the progress was monitored in more than 25,000 soil samples taken at the site. He attributes the good results to the ability of project supervisors and employees to create and maintain conditions in which oil-eating microbes would thrive.

Ross said that since the mid-1980s, the state Regional Water Quality Control Board has approved about two dozen bio-remediation projects within its jurisdiction of Los Angeles and Ventura counties. The work is becoming so common, he said, that the agency has developed a generic permit for the projects.

That doesn’t surprise Dennis Focht, a professor in the University of California, Riverside, soil and environmental sciences department. Focht said interest in bio-remediation has grown dramatically in the last several years.

“It’s an exponential growth,” Focht said. “With the economy the way it is, you’d expect the job market to be tight. But (bio-remediation) companies are calling here for help all the time. I really don’t have any problem placing graduate students.”