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Operating Industries, Inc. Landfill

In California, Many Hands Make Greener Work

In Monterey Park, California, about 10 miles east of downtown Los Angeles, the former Operating Industries, Inc. (OII) landfill that contained a wide array of wastes and the ever-present risk of fire is now a green hill. Part of this site may soon become a new retail shopping area, bringing new business to the area. More than 20,000 people live within three miles of the 190-acre site (which is divided into two parcels by the Pomona Freeway), and more than 2,000 people live within 1,000 feet of the former landfill.

The OII landfill became a priority for the U.S. Environmental Protection Agency (EPA) in the 1980s, and more than a decade of environmental projects have cleaned up and protected the air, soil, and groundwater at the site. With participation by the community and cooperation, financing, and cleanup by the more than 100 companies that are potentially responsible parties (PRPs) under the final remedy, the threat to residents' health and the environment has been greatly reduced.

Operating Industries, Inc. Landfill

Landfill operations began at the OII site by the owners, Monterey Park Disposal Co., in 1948. OII bought the site in the 1950s and continued disposal operations for nearly three decades. Nearly 4,000 companies dumped millions of gallons of commercial, residential, and industrial wastes during those years, about 300 million gallons of which were liquid industrial wastes. These wastes contaminated the air, groundwater, and soil, posed a fire risk, and threatened the health of nearby residents.

In January 1984, the State of California placed OII's landfill on the California Hazardous Waste Priority List, and the site shut down operations later that year. The EPA placed the site on Superfund's National Priorities List in May 1986.

In 1989, EPA and more than 100 companies that disposed of wastes in the landfill entered into a Consent Decree, and the companies formed a committee to focus on cleaning up the contamination. In 1992, EPA and the PRPs entered into another Consent Decree to perform the initial remedies. It required the PRPs-under EPA's supervision-to complete large parts of the gas control and landfill cover remedies chosen by EPA. The final remedy was signed in September 1996. Consent Decree 8, the final remedy settlement, was approved in May 2002, under which those companies that generated the most waste at the OII site agreed to implement the final remedy, provide financing for the efforts, and pay EPA's oversight costs.

Five Steps to a Greener and Cleaner Community

EPA and the dozens of PRPs are working together to clean up the OII site and protect the health of the community's citizens. More than 60 of the PRPs are required to implement the final remedy for cleanup of the OII site, which includes the following components:

  • Monitor landfill liquids: Landfill liquids at the site perimeter must be monitored through the use of monitoring wells or extraction wells. If contamination levels are too high, the extracted liquids are treated at the leachate treatment facility.

  • Clean up groundwater: Groundwater will be cleaned through allowing the contaminants to become harmless over time and distance. Monitoring the groundwater is required to ensure that if the natural process does not work, the water will be extracted and treated.

  • Operate and maintain the environmental control systems: The leachate treatment facility and the gas control and cover systems must be maintained properly. The gas control and cover systems include the landfill gas control system, the cover system, and the surface water management system. Site security must be provided.

  • Establish control mechanisms: The control mechanisms are to guarantee that the site will be used for appropriate purposes in the coming years and to ensure no one is exposed to contaminated groundwater.

The earlier Consent Decrees and the final remedy have led to a number of benefits. For example, the state-of-the-art Landfill Gas Treatment System (LFGTS) is running smoothly and destroying the landfill gas that is collected across the site. EPA worked closely with residents of the area to ensure they were given the opportunity to voice their opinions on the location of the LFGTS.

For eight years, an in-home air-monitoring program was undertaken to ensure the safety of nearby residences from dangerous gas migrating underground from the landfill. When a few homes were tested and found to have gas problems, cleanup systems were installed immediately. For several years before EPA ended the program, the Agency conducted testing but found no further problems in residents' homes.

The most obvious visible improvement is the new landfill cover that prevents rainwater from seeping into the landfill and gas from seeping out. About 6 million cubic yards of earth was removed and replaced with a geosynthetic clay liner and a six-foot-thick cover of clean soil and vegetation. The grass and other vegetation that was planted above the liner are native to the region and blend in with the surrounding land.

EPA, the PRPs, and the community are continuing to work together to complete the cleanup and plan for the future safety and development of the site. The grass and other vegetation now covering the site are just the beginning of ensuring that Monterey Park and Montebello residents are protected from the years of wastes that were dumped at the site.

Picture of Montebello homes

The new landfill cover keeps the residents of these Montebello homes protected from landfill gas.

Just the Facts:

  • With thousands of residents nearby and a 36-year history of commercial, residential, and industrial waste dumping, the OII landfill became an important priority for the State of California and EPA.

  • More than 60 of the PRPs will implement the final remedy, which includes monitoring landfill liquids, cleaning up groundwater, and operating and maintaining the environmental control systems. The rest will help finance the final remedy.

  • The new landfill cover prevents rainwater from seeping into the landfill and gas from leaking out, and provides a new landscape that blends in with the surrounding region.

  • Overall, the value of the total cleanup is $600 million.

With participation by the community and cooperation, financing, and cleanup by the more than 100 companies that are potentially responsible parties (PRPs) under the final remedy, the threat to residents' health and the environment has been greatly reduced.


Julie Santiago-Ocasio
Remedial Project Manager
EPA Region 9, (415) 972-3525

Vicki Rosen
Community Involvement Coordinator
EPA Region 9, (415) 972-3244

Visit the EPA Region 9 Web site for more information!

You may also view this Success Story in PDF format. (2 pp, 270 K, about PDF)

Picture of Landfill Gas Treatment System

Residents work closely with EPA to find a suitable location for Landfill Gas Treatment System.


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