Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
EPA #: CAD980737092
County: Los Angeles
Congressional District: 33
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 07/28/98
Final Date: 01/19/99
Pemaco is a former chemical mixing facility located in a light industrial and residential area at 5050 Slauson Boulevard, Maywood, CA. It is believed that Pemaco began on-site operations in the late 1940's. Pemaco was purchased by the LUX Chemical Company on July 27, 1988, and operations ended at the site on June 21, 1991. Hazardous substances are known to have been used at the facility, including chlorinated solvents, aromatic solvents, and flammable liquids.
Shortly after the closure of the facility, the Los Angeles County Hazardous Materials (Hazmat) Unit ordered the potentially responsible party to remove containers and drums of laboratory chemicals located in the warehouse and outside staging area. However in December 1993, the facility burned to the ground. Although the fire completely destroyed the warehouse, six 55-gallon drums, several above-ground storage tanks, and thirty-one underground storage tanks were unaffected by the fire. Due to safety concerns after the fire, the Environmental Protection Agency (EPA) was asked to conduct an emergency assessment and stabilize the site. The Agency responded by doing the following: 1) erecting a chain link fence with razor wire around the site; 2) verifying that all storage tanks were empty; 3) attaching locking caps to standpipes; and 4) removing a small number of 55-gallon drums for disposal. Having completed site stabilization activities, EPA referred the site back to the LA County Hazmat and informed the EPA Site Assessment program about the site for further study. After further studies to define the nature and extent of contamination, and initiation of cleanup activities, the site was placed on the NPL on January 19, 1999.
The Record of Decision for the Pemaco site was signed on January 13, 2005. Construction of the final remedy began during 2005. EPA completed construction of the remedy that was included in the Maywood Riverfront Park by June 2006. Construction of the treatment plant and placement of the equipment into the treatment plant continued until early 2007. EPA turned on the groundwater treatment system during April 2007. The vapor recovery and treatment system was turned on during May 2007, and the Electrical Resistance Heating remedy for the source area of the site began full operations during September 2007. EPA turned off the Electrical Resistive Heating remedy during April 2008 and permanently transferred vapor treatment over to carbon during June 2008. The concentrations in the ERH area, vapor treatment system and groundwater continue to decrease over time.
Contaminants and Risks
- Soil and Sludges
During the initial assessment study at Pemaco, the EPA found high levels of Volatile Organic Compounds (VOCs) in the soil beneath the site. The groundwater beneath the site was also contaminated with VOCs. VOCs at the site included: Perchloroethylene (PCE), Trichloroethylene (TCE), Trichloroethane (TCA), Dichloroethane (DCA) and vinyl chloride (VC). VOCs are known or suspected carcinogens and, therefore, could have posed a serious risk to neighbors if they were exposed to the chemicals.
Facility records indicate that the following materials were stored in tanks: methanol, ethanol, xylene, propylene glycol, 2-ethoxyethyl acetate, isopropyl acetate, isophorone, ethyl acetate, butanol, kerosene, tolusol, hexane, ispropanol, 2-butanone, 2-butoxy ethanol, toluene, acetone, and unleaded gasoline.
Investigation and Cleanup Activities
In 1998, the EPA selected the most effective and efficient method to clean up soils left behind after excavating the underground storage tanks. Commonly used throughout the country, soil vapor extraction removes vapors from the soil, then treats them with a thermal oxidation system. The treatment system burned the vapors as they passed through a heated system. The system included automatic safeguards to shut down in the event of malfunction, and it was tested to guarantee that emissions were within limits required by County, State and Federal Agencies.
The filter and thermal heating system worked as follows: 1) the soil gas passed through a filter system where a majority of contaminants were captured on filter material; 2) the unfiltered contaminants in the soil gas were then treated in a heated chamber that broke down the contaminants under temperatures exceeding 1,400 degrees F.
During incineration, most of the contaminants were reduced to non-toxic compounds, such as carbon dioxide and water. In 1998, the EPA collected weekly data on VOCs going into and coming out of the incinerator. The air at the fence line was sampled weekly to verify that no VOCs were leaving the site. EPA turned off the system later in 1998, because the sampling program did not measure potential dioxin emissions. However, based on tests of similar systems used on other projects, it is believed that emissions of VOCs, dioxins and other chemicals were low and did not pose an elevated threat to public health.
In September and October 1997, EPA conducted the first phase of the site cleanup by removing 29 underground storage tanks and several above-ground storage tanks. As part of the first phase, the facility was demolished, including removal of all piping, asphalt and concrete as well as the demolition of a large burned-out warehouse. Finally, the site was graded and grass was planted to prevent soil erosion.
In November and December 1997, the EPA tested the site to determine the extent of contamination. It was found that soil beneath the site was contaminated with several different volatile organic compounds (VOCs). These included several compounds that are commonly found in gasoline, such as toluene and xylene. Groundwater beneath the site was also contaminated with similar chemicals. Various methods to cleanup the site were evaluated.
In April 1998, the EPA started construction of a system to treat the VOCs in the ground beneath the site. The system was designed to remove and destroy underground soil vapors which would otherwise contribute to contamination of the groundwater, possibly impacting a drinking water aquifer. The VOCs beneath the site were extracted by on-site vapor extraction wells and then treated using granular activated carbon (GAC) and thermal oxidation. The GAC removed certain contaminants before the VOCs entered the thermal oxidation unit. The thermal oxidation unit destroyed the contaminants in a high temperature chamber designed for this purpose. EPA conducted additional testing of groundwater and soil to determine if further cleanup was necessary.
EPA signed the Record of Decision for the Pemaco Superfund site on January 13, 2005. The final remedy selected for the site is as follows:
- Soil cover and revegetation to address surface and near-surface soils.
- Treatment of upper vadose soils and perched groundwater, using a high-vacuum dual-phase extraction system [HVDPE]. This process uses ultraviolet oxidation [UV Ox] and granular activated carbon [GAC] for water treatment, and flameless thermal oxidation [FTO] and GAC for treatment of vapors.
- Treatment of the lower vadose soils and exposition groundwater, using electrical resistance heating [ERH] with vapor extraction [VE], vacuum-enhanced groundwater extraction, groundwater pump and treat [Groundwater P&T] and monitored natural attenuation (MNA). This process will use UV Ox and GAC for water treatment, and FTO and GAC for treatment of vapors.
EPA also added the following safety measures based on community concerns:
- · Indoor air sampling and additional vapor monitoring on Walker Avenue and 59th Street during FTO operations.
· Re-design of the FTO unit so that the heat exchanger vapor-phase GAC adsorption unit are installed to the post-exhaust side of the FTO unit to reduce the possibility of dioxin release to the environment, and
· Thorough emission monitoring of the FTO unit, including analysis of vapor samples for dioxins and other chemicals.
EPA finalized the entire treatment system during the Summer of 2006. However, construction on the underground conveyance piping and groundwater extraction wells began the Summer of 2005 when the City of Maywood started construction on the Maywood Riverfront park. EPA completed the design of the ERH system and the rest of the treatment plant the Summer of 2006.
EPA coordinated construction of the remedy for the Pemaco Superfund site with the construction of the Maywood Riverfront Park. As a result of this coordination effort, on-site construction of the remedy began on August 5, 2005. On-site construction included the installation of the groundwater extraction wells, vapor extraction wells, and underground piping that would transport both groundwater and vapor to the treatment plant. During August 2006, EPA continued its construction activities by building the foundation for the treatment plant and raising the walls for the treatment building. Construction of the treatment plant was completed by early December 2006 and EPA continued installation of the vapor recovery wells and electrodes located in the ERH source area. The soil vapor monitoring probes were installed along Walker Avenue during January 2007. EPA conducted indoor air sampling in the homes on 59th, and 60th Street during February 2007. The results showed that the subsurface contamination from the Pemaco site was not impacting the indoor air quality of the homes.
The contractors continued delivering and hooking up the equipment inside the treatment plant during early 2007. EPA turned on the groundwater treatment system during April 2007. The vapor treatment system was turned on during May 2007, and the ERH system was turned on during late August 2007. EPA continues to monitor both the groundwater treatment system and vapor monitoring system on a daily and weekly basis. EPA has collected samples for volatile organic compounds in both the vapor and groundwater waste streams. Sampling includes both instrumental monitoring as well as analysis of samples collected from various components of the treatment plant. EPA has also performed dioxin and furan testing on the vapor before it leaves the treatment plant. The sampling results show that the cleanup is proceeding in a safe manner and cleanup activities are not impacting residents living in the neighborhood close to the site or the park.
Cleanup of the groundwater and vapors will continue until cleanup levels are reached.
EPA conducted community meetings every 4 to 6 weeks while the remedy was constructed and the first year that the system was turned on. During late 2007 meetings were held during August and October. EPA also held meetings on January 31,2008, March 27, 2008, September 4, 2008, February 26, 2009, January 2010, and February 2011. EPA will continue to discuss the status of the cleanup and various sampling results at community meetings, and will send out email updates, as needed. A meeting will be scheduled during 2013.
EPA signed the Preliminary Closeout Report for the Pemaco Site in September 2007. This report documents the completion of the construction activities associated with implementing the remedy at the site. EPA also signed the Five Year Review for the Pemaco site on September 30, 2010.
Cleanup Results to Date
Since it was safe to develop the Pemaco property during construction of the treatment system, the City of Maywood began construction of the Maywood Riverfront Park during August 2005. The Maywood Riverfront Park is now complete and part of the Los Angeles River Greenway Project. The park opened in May 2008. EPA completed construction of the treatment system in the summer of 2006. The Electrical Resistive Heating System and the groundwater and vapor treatment system was turned on during 2007. The Electrical Resistive Heating System was turned off during April 2008. The groundwater and vapor treatment system continue to operate and concentrations of chemicals in the subsurface are decreasing.
The first Five Year Review Report was completed in September 2010 and concluded that -
The remedy at the Pemaco Superfund Site currently protects human health and the environment, because exposure pathways that could result in unacceptable risks are being controlled. However, in order to be protective in the long-term, the following actions should be taken:
1) The City of Maywood should change the zoning of the Pemaco property;
2) DTSC should finalize a Land Use Covenant to permanently change the site’s land use to recreational;
3) Assess the area around ‘D’ zone well MW-125-130 and evaluate whether further action is needed.
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.
Documents and Reports
Public Meetings: EPA completed the 5 Year Review Report during September 2010. A copy of the report is available on this web site. The last community meeting was held on March 22nd, 2012.
Public Information Repositories
The public information repositories for the site are at the following locations:
Maywood City Hall
4319 East Slauson Ave.
Maywood, CA 90270
Maywood Cesar Chavez Library
4323 E. Slauson Ave.
Maywood, CA 90270
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
Chatsworth Field Office
9211 Oakdale Avenue
Chatsworth, CA 91311-6505
After Hours (Emergency Response)