MONTEBELLO — Toxic and potentially explosive gases continue to seep from the Operating Industries Inc. hazardous waste site into surrounding neighborhoods in Montebello despite reports that odors from the closed landfill are diminishing, a federal report said.
A U.S. Environmental Protection Agency report released this month said potentially explosive methane and lesser amounts of vinyl chloride and other toxic gases continue to migrate into neighborhoods along the dump's southern and western boundaries.
The study proposes improving a system that collects and burns gas generated from decaying waste at the OII site, which is in Monterey Park and on Montebello's northern border. The EPA is in the midst of a multi-year study to determine how to clean up the landfill, which was closed in 1984 and is on the federal Superfund list.
"Methane build-up in enclosed spaces . . . has been demonstrated at the OII site and these levels may be acutely dangerous to life and property to residents surrounding the site," the report said.
"The neighborhood to the southwest has continued to exhibit elevated levels of methane regardless of the existing (gas) migration control systems at the landfill," the report said.
Not an Immediate Danger
But EPA spokesman Kevin Dick said the migrating methane is not an immediate danger because measures have been taken to keep it from accumulating in enclosed areas where high concentrations were found.
Methane was detected in some residential water meter boxes, which were vented in late 1986 to guard against explosion, the report said. The water meter boxes are checked periodically for methane, Dick said.
Air monitoring in homes has not turned up dangerous concentrations of methane gas from the landfill, although the potential is there, he said. Additional residential air monitoring is to take place later this year.
The study also concluded that about 2,150 residents living within 1,000 feet of the landfill--all in Montebello neighborhoods--probably are being exposed to small amounts of toxic gases, including cancer-causing vinyl chloride and benzene.
Pending further testing, the EPA estimates that the level of pollutants in the neighborhoods surrounding the landfill would result in about 1.5 additional cases of cancer per 10,000 people exposed over a lifetime.
That preliminary assessment is based on air samplings from 1983 to 1986. Vinyl chloride was detected in houses near the dump in 1985, the EPA report said. The EPA plans to begin monitoring the air around the dump in the next couple of months, Dick said.
"We know there's vinyl chloride in the gas that's produced in the landfill. And we know that that gas is being emitted from the landfill," Dick said. "From that you can infer that there is vinyl chloride around the site."
The existing gas control system has helped block gas migration into the areas southeast of the dump, the report said. No accumulations of gas have been detected in neighborhoods to the northwest, the report said.
Hank Yoshitake, president of a citizens group that pressed for closure and cleanup of the landfill, said he had not studied the report. But Yoshitake said Homeowners to Eliminate Landfill Problems strongly supports measures to stop gas migration.
"There are some toxics in the gases," Yoshitake said. "That's why it's important to do something as quickly as possible. We'd like to see it improved to where there's no migrating gas."
An air dam, which forces waste gases back to the center of the landfill, has been used in recent years.
Yoshitake, who lives in Montebello within a block of the dump, and other residents say odors from the landfill have been reduced substantially.
The landfill consists of a 145-acre parcel south of the Pomona Freeway and a 45-acre section north of the freeway.
The landfill accepted municipal and industrial waste from 1948 to 1984. Liquid hazardous wastes also were dumped from 1976 to 1984.
The EPA is proposing to upgrade the gas collection and flaring system, which currently only gathers and burns waste gas from the south parcel. The improvements include extending the gas collection system to the north parcel and building new flaring facilities.
Proposed for North Parcel
The improved system would collect an estimated 90% of the methane gas generated by the landfill, as well as other waste gases. The existing system collects about 52%, officials said.
The new flaring facility is being proposed for the north parcel because it would be farther from homes. Most of the toxics in the landfill gas would be destroyed during incineration, Dick said.
It would cost an estimated $73.1 million to build and maintain the improved system for 30 years, the report said. The EPA is to decide later this year whether to proceed with the recommended improvements or to use alternatives. The proposed collection and flaring system would not be fully operational until 1991, EPA spokeswoman Michele S. Dermer said.