Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Operating Industries, Inc. Landfill
EPA #: CAT080012024
County: Los Angeles
City: Monterey Park
Congressional District: 31
Other Names: Monterey Park Landfill
The 2015 Five-Year Review process for the OII Site has begund. It is scheduled for completion September 30, 2015.
On this page
Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 10/15/84
Final Date: 06/10/86
The Operating Industries, Inc. (OII) Landfill site is located approximately 10 miles east of downtown Los Angeles at 900 Potrero Grande Drive in the City of Monterey Park. The Pomona Freeway divides the 190-acre site into two parcels namely: South and North Parcels. The Monterey Park Disposal Co. began landfilling operations at the site in 1948, and in the 1950s Operating Industries, Inc. purchased the landfill and continued operations. A.H.A.S., Inc. is the current owner of record of the North Parcel, and Operating Industries, Inc. is the current owner of record of the South Parcel. Over the life of the landfill, many wastes have been disposed there. The South Parcel, approximately 145 acres in size, received the majority of wastes including residential and commercial refuse, liquid wastes, and various hazardous wastes. The North Parcel is about 45 acres in size, and approximately 10 acres of the western side of the North Parcel were used as a landfill and received primarily construction and debris (C&D) waste. The majority of the C&D waste on the North Parcel is composed of wood, glass, metal, paper, cardboard, brick, asphalt, concrete, and plastic. In January 1984, the State of California placed OII on the California Hazardous Waste Priority List. The landfill stopped accepting wastes and was closed in late 1984. The U.S. EPA proposed OII to the NPL in the same year and began conducting studies and taking actions to protect the local environment and those who live near the site. Approximately 23,000 people live within three miles of the site, and 2,100 people live within 1,000 feet of the landfill.
Contaminants and Risks
- Soil and Sludges
South Parcel: Air, groundwater, soil, and leachate contain various organic and inorganic compounds. Potential health threats include inhalation of gases and direct contact or accidental ingestion of contaminated groundwater, soils, or leachate. There is also the potential for an explosion or fire at the site.
North Parcel: The construction and debris (C&D) waste on the North Parcel produces a very small amount of landfill gas. Groundwater around the North Parcel contains various organic and inorganic compounds. Accidental ingestion of contaminated groundwater could be a potential health threat.
Who is Involved
This site is being addressed through actions by the Federal Government and Potentially Responsible Parties (PRPs).
Investigation and Cleanup Activities
This site is being addressed in five stages: emergency actions and four long-term remedial phases focusing on cleanup of the entire site, including leachate management, installation of a gas control and landfill cover, and site control and monitoring.
Emergency Actions: In the late 1980s, EPA fenced the site and posted a guard to keep trespassers from coming into contact with hazardous substances. The EPA has conducted a number of emergency actions including rehabilitation of the former main gas flare station, slope stability and erosion control improvements, surface runoff and drainage improvements, and off-site trucking and treating of the leachate collected at the site.
Entire Site: EPA has completed an investigation and study to explore the nature and extent of groundwater contamination from the landfill and to select remedies to clean up the entire site. This information is presented in the Remedial Investigation and Feasibility Study Reports. The Remedial Investigation Report shows that the worst groundwater contamination is around the perimeter of the landfill. The levels of contaminants rapidly drop off to near drinking water standards a short distance away from the perimeter of the landfill. Various alternatives were evaluated for cleanup of the contaminated groundwater in the Feasibility Study. The Record of Decision (ROD) for the Final Remedy was signed in September 1996. EPA's selected alternative includes control of landfill liquids around the perimeter of the landfill and natural attenuation and monitoring of contaminated groundwater away from the landfill perimeter. The selected alternative also includes long-term site monitoring, operations, and maintenance of site remedy systems.
Prior to issuing the Final ROD in September 1996, the EPA issued two interim RODs. The interim ROD for the site control and monitoring was issued in July, 1987 and the interim ROD for leachate management was issued in November, 1987.
The Site control and monitoring interim ROD (SCM ROD) provided a mechanism to undertake activities prior to implementation of the final remedies to stabilize the landfill and minimize the uncontrolled release of landfill gas. The leachate management interim ROD (Leachate Management ROD) addressed the treatment of the leachate generated at the OII site. Both the interim RODs were later superseded by the Final ROD issued in September 1996.
In addition to the above listed two interim RODs, EPA issued the landfill gas migration control and the landfill cover ROD in September 1988. This ROD selected a permanent remedy for landfill gas control and landfill cover. The landfill gas migration control and landfill cover ROD was amended in September 1990.
Site Control and Monitoring (SCM): A variety of daily site activities are necessary to maintain the landfill and the existing environmental control facilities. These activities include the operation of the gas control systems and landfill gas treatment facility; maintenance of the landfill cover, access roads, drainage facilities, and security fences; and monitoring of the environment both on and off the site. Activities also include installation of new gas recovery wells and monitoring probes to allow more gas to be collected, repairs to the gas control system at different on-site locations to improve collection of landfill gas, and improvements to the site irrigation system. In addition, there is continued monitoring of the leachate collection and treatment systems. These site control and monitoring activities have been ongoing since 1987.
Most of the site control and monitoring activities are for the South Parcel.
Leachate Management: Approximately 300 million gallons of liquid industrial wastes were disposed in the South Parcel of the landfill. Leachate forms from these liquids as they mix with water at the site. If this leachate is not controlled, it may contaminate the soil, surface water, or groundwater. Initially, leachate was collected and stored in temporary on-site tanks and then removed by trucks for off-site treatment and disposal. In 1991, construction of an on-site leachate treatment plant began on the North Parcel, away from homes. The Leachate Treatment Plant is now operating and treats only liquids from the site. Under EPA's selected alternative for final remedy, the Leachate Treatment Plant will be used to treat additional liquids collected around the landfill perimeter.
The North Parcel has not shown any indication of the leachate being present. Therefore, no leachate management for the North Parcel is being planned at the present time.
Landfill Gas Migration Control and Landfill Cover: In 1990, EPA amended the remedy selected to address landfill gas migration. Three site systems were selected, which include a system for gas control, a landfill cover, and surface water management. The gas control system controls both surface emissions and subsurface movement of gas coming out of the landfill.
South Parcel: The system includes new gas extraction wells, new gas piping, additional gas destruction capacity, and monitoring facilities. A landfill cover system also was built to help prevent the movement of gas through the surface of the site and to decrease odors, dust, and landfill gas emissions. The cap reduces infiltration of water and oxygen into the landfill, and is designed to prevent erosion and movement of material down the slopes of the site. The addition of the landfill cover also enhances the overall effectiveness of the gas control system, and improves the appearance of the site. To the extent possible, vegetation has been planted over the cover. The surface water management system minimizes the potential for runoff of landfill contaminants during rainfall and erosion of the cover. Design of these remedies for South Parcel began in 1992 and construction was completed in 2000.
North Parcel: Out of 45 acres, only a 10-acre area is known to have been used as a landfill, and it contains mostly construction and debris (C&D) waste. The C&D waste present on the North Parcel has not shown any significant amounts of the landfill gas being generated. A final cover and a passive landfill gas control system has been installed on the 10-acre landfill area. The final cover design will allow for redevelopment of the North Parcel. Construction of the final North Parcel cover and the landfill gas control system were completed in Summer 2009. North Parcel is ready for the retail market place redevelopment.
Groundwater: The final piece of the groundwater remedy (construction and performance testing of the perimeter liquids control system) was completed by August 2012.
To date, settlements between EPA and potential responsible parties have totaled over $600 million. Most recently, in May 2002 the court approved a settlement between EPA and 161 responsible parties and the state of California for the implementation of the final cleanup remedy at OII. This settlement is valued at $340 million in clean-up work and payments. When completed, the OII cleanup, which began in 1984, will protect human health and the environment from the release and migration of contaminants from the landfill. A leachate treatment system, landfill gas collection system and a landfill cover have been constructed. Additional systems to treat landfill liquids collected from extraction wells at the Site are being implemented.
The remedies selected for the site leave waste in-place at the landfill, therefore, EPA will review the remedy every five years to ensure that it remains protective of human health and the environment.
Cleanup Results to Date
Landfill Cover System
South Parcel: Work on the landfill cover system continues. As the neighbors closest to the OII site are aware, the vegetation planted at the landfill has taken root since completion of the cover. Designed to resemble the vegetation on nearby hills, the plants and ground cover turn green and lush during the wet months, and brown in the summer and fall. Although we are very pleased with the landfill’s appearance, site managers are continuously working to improve the vegetation. Over time, we expect the OII site to look even better. Unfortunately, the cover system installed on the North Slope of the South Parcel (the very steep slope that overlooks the 60 Freeway) show signs of cracking on recurring basis. These cracks are not currently affecting the stability of the landfill or the effectiveness of the cover in preventing water from infiltrating the landfill. To maintain the stability and effectiveness of the North Slope cover system, cracks are filled with grout (made from sand and clay) as soon as they are discovered. The site managers continue to watch the North Slope closely so that they may quickly respond to any problems that develop, and EPA is monitoring the situation. In addition, residents who live near the site will occasionally see road maintenance. These roads are essential for enabling workers to access all areas of the landfill, and they must be kept in good condition to be safe and effective.
North Parcel: As of September 2009, construction of the cover for the North Parcel is complete. The cover encompasses the 10-acre area on the North Parcel that received construction and debris waste. The cover was designed to facilitate redevelopment of the North Parcel.
Landfill Collection Systems
There are two substances produced by the landfill that are continuously collected and treated: landfill gasses and landfill liquids. Landfill gasses form due to the decomposition of trash and organic materials within the landfill. Liquids accumulate from water percolating through the landfill. This water can pick up potentially harmful compounds and form leachate. The gas collection system pulls the gas from deep within the landfill and burns it at the gas treatment system on the North Parcel. This treatment system was built several years ago to take the place of the old, inefficient flare system. It is closely monitored, and the monitoring data confirm that the facility is working better than required. In addition, EPA has approved the use of micro-turbines to generate electricity from landfill gasses and they have been operational since 2002. This electricity is being used to operate site systems, saving both energy and money. All emissions from the microturbines are captured and sent back to the gas treatment system to ensure all contaminants are destroyed. A series of wells and pipes collect leachate and send it to the leachate treatment plant, also located on the North Parcel. Following treatment of these liquids at the plant to neutralize any hazardous constituents, the liquids are disposed in the sanitary sewer. This system continues to operate effectively.
Groundwater Cleanup and Control
Although groundwater in the vicinity of the OII site is not currently used as a drinking water source, it is a natural resource that must be protected. To this end, EPA has approved a long-term plan to monitor the groundwater around the perimeter of the landfill to make sure that the selected remedy of natural attenuation works as expected and that contaminated groundwater does not continue to spread. The groundwater monitoring plan approved by EPA establishes the required number and locations of monitoring wells to be installed. The monitoring plan also specifies procedures for how the sampling is conducted and how often samples are taken. As a result of the on-going monitoring and related remedy design processes, EPA currently expects additional monitoring wells to be installed northeast of the North Parcel and on the southeast side of the South Parcel. In addition, EPA is evaluating hydrogeologic conditions of the aquifer through pump tests and core samples to better understand the potential for contaminant migration. In the event that natural attenuation does not work, EPA may require that more wells be installed to pump out liquids for treatment at the leachate treatment plant.
In-Home Air Monitoring and Remediation Completed in 2001
The project to monitor the air inside residences near the OII site began in 1993 to make sure harmful gas migrating underground from the landfill did not accumulate in homes. This project involved bi-annual monitoring of the air inside some homes adjacent to the South Parcel. A few homes were found to have landfill gas problems, and remediation systems were installed following the initial 24-hour testing. With the increased gas collection system and capping that occurred on site, the gas in the landfill became far more controlled. For several years prior to ending the in-home monitoring program in 2001, EPA saw no evidence of an indoor air problem in any of the homes we tested. Subsequently, we removed the gas collection systems in the affected homes and have stopped the periodic random sampling.
Potentially Responsible Parties
Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.
Almost 4,000 companies are known to have disposed of commercial and industrial wastes at the OII site. The quantities of waste disposed by each of these companies range from very small quantities to over 15 million gallons.
- EPA considers the ten parties who disposed of the largest amounts of liquid commercial and/or industrial wastes at the OII Site to be "major" PRPs. Each of the major PRPs contributed at least 5 million gallons of commercial and industrial wastes to the OII Site. EPA has designated the remaining waste contributors, each of which disposed of less than 5 million gallons of liquid commercial and/or industrial waste to the OII Site, as potential "de minimis" waste generators. De minimis waste generators are parties whose waste contribution to a Superfund site was comparatively minimal both in terms of volume and toxicity (prior to the negotiation of the Eighth Partial Consent Decree (“CD-8"), major party/de minimis party volumetric threshold was 110,000 gallons. This threshold was increased to the current 5 million gallons in order to facilitate the successful negotiation of CD-8). Under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), EPA may offer special settlements to de minimis parties which convey significant benefits to settling parties, including protection from further enforcement in the form of covenants not to sue that do not contain exceptions in the event new information or unknown conditions are encountered subsequent to the settlement. Region 9 has conducted several rounds of settlements with hundreds of parties at the OII Site already, and in March 2010, issued the final de minimis settlement offer to approximately 650 parties (a copy of the proposed settlement and related information can be found under "Legal Documents" in the "Documents and Reports" section below).
Documents and Reports
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Public Meetings: The U.S. EPA has begun the 2015 Five-Year Review (FYR) process for the OII Site. Your input will assist EPA as it evaluates the effectiveness of the remedy in place to determine that it continues to be protective of human health and the environment. If you would like to be involved, please contact Jackie Lane at (415) 972-3236 or by email at email@example.com by 11/19/14. To review the 2010 FYR report, go to the "Document and Report" section above. The 2015 FYR is scheduled for completion September 30, 2015 and it will be placed in the site information repository and on this web page.
Public Information Repositories
The public information repositories for the site are at the following locations:
Bruggemeyer Memorial Library,
318 South Ramona Avenue,
Monterey Park, CA 91754
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
9211 Oakdale Avenue.
Chatsworth, CA 91311
Beverly Hills, CA 90210
After Hours (Emergency Response)