Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
San Gabriel Valley (area 4) City Of Industry, Puente Valley
EPA #: CAD980817985
County: Los Angeles
City: Los Angeles
Congressional District: 38
Community Open House
Tuesday, October 16th, 2012
6:00 pm - 8:00 pm
La Puente City Hall, 15900 E. Main Street
Come learn more about upcoming field work, click here for the factsheet
New 12/2011 San Gabriel Valley (All Areas) cleanup fact sheet is now available.
On this page
Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 09/08/83
Final Date: 05/08/84
The San Gabriel Valley Area 4 site is an area of contaminated groundwater that runs along San Jose Creek in La Puente. This site is one of four Superfund sites located in the 170-square-mile San Gabriel Valley. More than 30 square miles of groundwater under the Valley may be contaminated. The sites include four large areas of groundwater contamination that underlie significant portions of the Cities of Alhambra, Arcadia, Azusa, Baldwin Park, Industry, El Monte, La Puente, Monrovia, Rosemead, South El Monte, West Covina, and other areas of the San Gabriel Valley. Contamination of the groundwater by volatile organic compounds (VOCs) was first detected in 1979 when Aerojet Electrosystems in Azusa sampled nearby wells in the Valley County Water District. Following this discovery, the California Department of Health Services (CDHS) initiated a well sampling program to assess the extent of contamination. By 1984, 59 wells were found to be contaminated with VOCs. The basin's groundwater provides approximately 85 percent of the domestic water supply for more than 1,000,000 people who live in the Valley. Water supply wells are used in the basin to extract groundwater for industrial, business, agricultural, and domestic uses. Water utilities in the area provide clean water that meets all state drinking water standards.
Contaminants and Risks
- Soil and Sludges
Groundwater and soil are contaminated with various VOCs. The primary VOC contaminants are trichloroethylene (TCE), perchloroethylene (PCE), and 1,4-dioxane. Low levels of perchlorate have also been detected. People who inhale vapors from groundwater that contain VOCs could be exposed to hazardous substances. Currently, all drinking water provided meets Federal and State drinking water standards.
Investigation and Cleanup Activities
The cleanup approach is groundwater extraction and treatment at the western end of the Puente Valley. Two separate projects are planned, known as the shallow zone and intermediate zone remedies.
The shallow zone remedy will include ten extraction wells capable of pumping approximately 2.0 million gallons per day (MGD). The project will include granular activated carbon water treatment equipment (for removal of VOCs), advanced oxidation equipment (for removal of 1,4-dioxane) and, ion exchange equipment (for removal of perchlorate).
The treated water from the shallow zone remedy was to be originally discharged to a local flood control channel. In light of new environmental concerns, EPA is re-evaluating this discharge option.
The intermediate zone remedy will include six extraction wells capable of pumping approximately 1.5 MGD. The project will include granular activated carbon water treatment equipment for removal of VOCs and, if necessary, advanced oxidation (for removal of 1,4-dioxane) and ion exchange (for removal of perchlorate). Treated groundwater is anticipated to be provided to a local water supply distribution system. During low demand winter months portion of the treated water may need to be discharged to San Jose Creek.
Area-wide Contamination: In 1984, the EPA began a study of the nature and extent of contamination throughout the San Gabriel Valley. The intent of this investigation is to identify specific areas of the site for focused study and provide support to ongoing activities at all areas of the San Gabriel Valley site.
Puente Valley Area: Potentially responsible parties, under EPA oversight, investigated the nature and extent of contamination at the Puente Valley area. This phase of the project, commonly referred to as the Remedial Investigation/Feasibility Study (RI/FS) was completed in June 1996.
Source Identification and Control: The California Regional Water Quality Control Board, Los Angeles Region, working under a Cooperative Agreement with the EPA, is identifying sources of contaminants. To date, nearly 400 individual facilities throughout the San Gabriel Valley have been confirmed as having soil contamination.
The selected remedy for the PVOU includes extraction, containment and treatment of contaminated groundwater in the shallow and intermediate zones at the mouth of Puente Valley. The remedy also includes a set of wells for monitoring the groundwater in the shallow, intermediate, and deep zones at mid-valley and the mouth of the valley, to ensure that the remedy meets the performance criteria set in the September 1998 Record of Decision (ROD) and updated in the 2005 Explanation of Significant Differences (ESD) which included the contaminants 1,4-dioxane and perchlorate.. Cost estimates for the remedy assume that additional extraction and treatment systems will be needed for both the intermediate and shallow zones. The estimate also assumes that the treatment technology will be air stripping and adsorption of VOCs in the off-gas. The net worth of this interim remedy, at the time of the ESD, was approximately $51 million.
This remedy specifies criteria that the treatment system must meet while providing flexibility in implementing the system. For example, in the intermediate zone at the mouth of the valley, the ROD provides the option to either install a series of extraction wells or use an existing well-field extraction system, as long as the following performance criteria is met: "the remedial action shall provide sufficient hydraulic control, through groundwater extraction, to capture groundwater contaminated with VOCs above MCLs [Maximum Contaminant Levels allowed by State law], and prevent it from migrating into or beyond the B7 well field area (depending on the location of extraction)." The shallow zone remedy must comply with the following performance criteria: "the remedial action shall apply measures necessary to prevent further migration of groundwater in the shallow zone with VOCs above 10 times MCLs from migrating beyond its current lateral and vertical extent."
Extracted groundwater will be treated to remove VOCs before it is discharged. EPA is evaluating discharge options in light of potential environmental concerns regarding discharge to surface water.
The Remedial Investigation and Feasibility Study was completed in May 1997 and a cleanup plan adopted in September 1998 (the Puente Valley Operable Unit Interim Record of Decision). In September 2001, after negotiations failed, EPA ordered Carrier Corporation to design, build, and operate the shallow zone remedy. In March 2002, EPA issued a second order to TRW Inc. to design, build, and operate the intermediate zone remedy. TRW is now known as Northrop Grumman Space and Mission Systems Corporation (Northrop Grumman)). In June 2005, EPA issued an Explanation of Significant Differences (ESD) to update the 1998 cleanup plan by requiring additional treatment for 1,4-dioxane and possibly perchlorate. The Record of Decision is available on EPA’s website as part of the site overview for the San Gabriel Valley Area 4 Superfund Site.
In August 2005, EPA and the Department of Justice reached an agreement requiring United Technologies Corporation (UTC) and its subsidiary Carrier Corporation to implement the shallow zone remedy. Significant work is underway. The Consent Decree also requires Carrier Corp. to carry out an environmental project at a former duck farm overlying a portion of the contaminated groundwater. The Watershed Conservation Authority purchased the former duck farm and plans to use it for the benefit of the local community.
In August 2009, EPA and the Department of Justice reached an agreement with Northrop Grumman Corp. to implement the Intermediate Zone remedy in the form of a Consent Decree. In September 2011, EPA issued ordered Northrop Grumman to investigate, design, build, and operate the Shallow Zone South Remedy after lead agency oversight was transferred from the Los Angeles Regional Water Quality Control Board for work related to the former Benchmark Technology facility located in the City of Industry.
With work underway in both the shallow and intermediate zones, EPA is continuing to negotiate settlement agreements with remaining parties. Eleven settlements together worth approximately $16 million have been negotiated so far and others are in progress.
Cleanup Results to Date
EPA continues to oversee installation of wells, pipelines, and other remedial activities in the City of La Puente, City of Industry and unincorporated areas of Los Angeles County. These structures are part of a groundwater cleanup project called the “San Gabriel Valley Superfund Site, Puente Valley Operable Unit” (PVOU). The goal of the project is to protect drinking water.
The cleanup system consists of three major parts: the “Intermediate Zone (or IZ) remedy”, the “Shallow Zone North (or SZ North) remedy”, and the “Shallow Zone South (or SZ South) remedy”. Northrop Grumman Corp. is responsible for the IZ and SZ South cleanup systems. Northrop Grumman has completed installation of extraction wells and pipelines for the IZ Remedy and construction of the water treatment plant is expected in fall 2014. United Technology Corporation/Carrier has completed installation of extraction wells and is conducting additional field activities for the SZ North. Northrop Grumman Corp. is currently conducting field investigations for the SZ South. Pipeline installation and construction of the SZ treatment plant system will begin as soon as EPA selects an alternative discharge option for treated water.
EPA thanks residents, business owners, and local governments for their cooperation an patience during site investigation and monitoring well installations. We are currently re-evaluating and will finalize the Remedial Design in light of new environmental concerns by Fall 2014. We expect to complete all construction for the project by May 2016. Once constructed, the three groundwater cleanup systems will operate for approximately 15 to 30 years.
EPA and the companies have notified local residents and businesses of work through fact sheets and in flyers. EPA also hosted community meetings in La Puente to describe pipeline and other construction activities.
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 Information Repositories
The public information repositories for the site are at the following locations:
Hacienda Heights Public Library
16010 La Monde Street,
Hacienda Heights, CA 91745
La Puente Public Library
15920 E. Central Avenue
La Puente, CA 91744
West Covina Library
1801 West Covina Parkway
West Covina, CA 91790
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
8800 Cal Center Drive
Sacramento, CA 95826
(Intermediate Zone Remedy
Shallow Zone South Remedy)
Bradley A. Barquest
(Shallow Zone North Remedy)
Lewis Groundwater Consulting on behalf of Northrop Grumman Corp.
5 Munroe Street
Foxborough, MA 02035
United Technologies / Carrier,
9716 Avocet Street NW,
Coon Rapids, MN 55433
After Hours (Emergency Response)