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Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations


EPA #: CAD980737092

State: California(CA)

County: Los Angeles

City: Maywood

Congressional District: 33

Other Names:

Bulletin Board

On 10/13/17, this website will no longer be updated. Site information will be migrated to the new web page at: http://www.epa.gov/superfund/pemaco .
EPA appreciates your patience through this transition. If you have questions, please contact EPA staff listed below.


Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 07/28/98

Final Date: 01/19/99

Deleted Date:

Pemaco was 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.

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Contaminants and Risks

Contaminated Media
  • Groundwater
  • 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.

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Who is Involved

Fund Lead

          All cleanup costs are being paid by the federal government.

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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 removed vapors from the soil, then treated them with a thermal oxidizer. 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 thermal heating system worked as follows: 1) the soil gas entered a heated chamber that had temperatures exceeding 1,400 degrees F which broke down the contaminants. 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 that could occur because the temperatures in the incinerator were so high. 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.

Initial Actions

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 by the removal program. As part of the removal program, 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 former underground storage tank area beneath the site. The tanks were removed and the contaminated soil that existed within the tank farm area was cleaned up utilizing soil vapor extraction. 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 in the underground storage area was extracted by on-site vapor extraction wells and then treated via thermal oxidation. 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.

Remedy Selected

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 were 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.

Remedy Design

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.

Cleanup Ongoing

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. While the FTO was in operation, EPA performed dioxin and furan testing on the vapor before it left the treatment plant. The sampling results showed that the cleanup was proceeding in a safe manner and cleanup activities were 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, February 2011, March 22, 2012, May 1, 2014, and August 12, 2015 . 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. The next community meeting is scheduled for September 8, 2016.

    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 First Five-Year Review on September 30, 2010 and the Second Five-Year Review on September 22, 2015; conclusion summaries are in the "Cleanup Results to Date" section and the reports are available in the "Documents and Reports" Section on this page.

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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.

The Second Five-Year Review Report was completed in September 2015 and concluded that - The remedy at the Pemaco Superfund Site currently protects human health because exposure pathways to contaminated soil and groundwater are being controlled. The Report noted that contaminants of concern in four hydrogeological zones (A,B,C, and D) have shown that some wells have been increasing in concentrations since 2011. When the Second Five Year Review was signed sampling results couldn't determine whether or not the increasing concentrations were coming from an unknown source or caused by the site. The report recommended that in order for the remedy to be protective in the long-term, the following actions are necessary:
1. Investigation of the increasing trends of contaminant concentration in each aquifer and the
evaluation of the effectiveness of the groundwater extraction and treatment system and investigating the possibility of an unknown source contributing to the increasing concentrations which will require installation of additional wells and field sampling.
2. Identification of the full extent of contamination in each zone (onsite, off site and vertically);
3. Capping and revegetation of the ERH area; and
4. Finalization of a Land Use Covenant by DTSC, U.S. EPA and City of Maywood(draft sent to the State of California during April 2015).

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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.

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Documents and Reports

Hide details for Administrative RecordsAdministrative Records
Remedial AR (Part 1)
Remedial AR (Part 2)
Removal Action #1
Removal Action #2
Hide details for Community InvolvementCommunity Involvement
03/01/10Draft Annual Operating Report 2008 & 2009 - Pemaco Superfund Site
01/01/11Pemaco Treatment Systems Sampling Data - 1/2008 - 12/2010
01/25/11Presentation from January 25th, 2011 Public Meeting (English & Spanish)
Hide details for Fact SheetsFact Sheets
03/01/98Cleanup Continues / Limpiadora de Pemaco Continua
02/01/99Soil Cleanup Effective
08/01/01Fact Sheet Announcing Community Meeting (English/Spanish)
09/01/01Presentation of Pemaco Field Investigation at Community Meeting
03/01/04Pemaco Proposed Plan (English and Spanish)
07/01/05Planning, Design and Community Input
01/01/06Pemaco Superfund Site Update
06/01/07Hoja de Información - Preguntas y Respuestas Comunes sobre el
Parque Riverfront de Maywood y el Sitio Superfund Pemaco
06/01/07Pemaco Superfund Site - Community Meeting Notice
06/07/07Pemaco Superfund Site Update
Actualización, Sitio Superfund Pemaco
06/29/07Question and Answer Fact Sheet - Maywood Riverfront Park and the Pemaco Superfund Site
07/01/07Pemaco Superfund Site Community Meeting Notice
Sitio Superfondo Pemaco Anuncio de Reunión Comunitaria
08/01/07Pemaco Superfund Site Community Meeting Notice - English / Spanish
09/01/07Pemaco Superfund Site Community Meeting Notice (English & Spanish )
11/07/07Pemaco Superfund Site Community Meeting Notice
01/18/08Pemaco Superfund Site Community Meeting Notice (English & Spanish)
03/27/08Pemaco Superfund Site Community Meeting Notice (English and/y Espanol)
08/25/08Pemaco Superfund Site Community Meeting Notice / Aviso de Reunión Comunitaria del Sitio Pemaco del Superfondo (English and Spanish)
02/11/09Pemaco Site Community Meeting Notice / Aviso de Reunión Comunitaria del Sitio Pemaco del (English and Spanish)
04/21/10Public Notice - EPA Initiates Five-Year Review of Cleanup at the Pemaco Superfund Site / Aviso Público - EPA Inicia la Revisión de Cinco Años de Limpieza en el Sitio Superfund Pemaco
01/10/11Pemaco Public Meeting Flyer, January 25, 2011
03/08/12Pemaco Superfund Open House Invitation (English & Spanish)
04/25/14Pemaco Cleanup Update (English & Spanish)
04/25/14Pemaco Meeting Notice
10/01/14The United States Environmental Protection Agency begins the second Five-Year Review of cleanup at the Pemaco Superfund Site (English and Spanish)
Hide details for Records of DecisionRecords of Decision
01/13/05Pemaco Superfund Site Maywood , California - January 13, 2005
Hide details for Technical DocumentsTechnical Documents
04/05/04Pemaco Superfund Site Feasibility Study
11/09/06EPA Safety Letter - Maywood Riverfront Park
08/24/07Native Soil Stockpile Sampling Report (Soil Piles on Site)
09/30/10First Five-Year Review of Cleanup - Pemaco Superfund Site
11/24/14First Semi-Annual Groundwater Monitoring Report, 2013 June Monitoring Event for Pemaco Superfund Site, Maywood, CA
09/22/15Second Five-Year Review Report

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Community Involvement

Public Meetings: The last community meeting was held on Wednesday, August 12, 2015, at the Heliotrope Elementary -School Auditorium, 5911 Woodlawn Ave., Maywood, CA 90270 regarding project progress. The next community meeting is scheduled for September 8, 2016.

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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

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

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EPA Site Manager
Rosemarie Caraway
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Carlin Hafiz
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
Lori Parnass
Department of Toxic Substances Control
Chatsworth Field Office
9211 Oakdale Avenue
Chatsworth, CA 91311-6505
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

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