SAN GABRIEL VALLEY (AREA 4) CITY OF INDUSTRY, PUENTE VALLEY

Description and History

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.

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Contaminants and Risks

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.

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Who is Involved

This site is being addressed through Federal and State actions.

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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 nine 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, if necessary, ion exchange equipment (for removal of perchlorate). The treated water may be provided to a local water supply distribution system or discharged to a local flood control channel.

The intermediate zone remedy will include six extraction wells capable of pumping approximately 1.4 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.

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). 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 remedy, at the time of the ROD, was $27.8 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 to either San Jose Creek or to a municipal water supply system.

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.

EPA is currently working with Northrop Grumman, who is implementing the Intermediate Zone remedial system to convert the existing Unilateral Administrative Order to a Consent Decree

With work underway in both the shallow and intermediate zones, EPA is continuing to negotiate settlement agreements with remaining parties. Two settlements together worth approximately $10.6 million have been negotiated so far and numerous others are in progress.

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Cleanup Results to Date

Design of the shallow and intermediate remedies is underway. In early 2006, Northrop Grumman and UTC/Carrier began to install extraction wells in La Puente and Industry and unincorporated areas of Los Angeles County. EPA and the companies notified local residents and businesses of the work in a fact sheet. EPA also hosted a community meeting in La Puente to describe upcoming well installation activities.

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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.

PUENTE VALLEY OPERABLE UNIT
SPECIAL NOTICE RI/FS - 1993
ALPHABETICAL DISTRIBUTION LIST
(24 Kb, PDF format, requires Adobe Acrobat reader)

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Documents and Reports

Administrative Records
		Puente Valley Operable Unit
		Puente Valley OU, Administrative Order for Access
		Puente Valley OU/ Supplement #3
Fact Sheets
	01/01/98	San Gabriel Valley Superfund Site-Puente Valley Operable Unit Proposed Plan
	02/01/98	EPA Extends Comment Period on Proposed Plan to Address Ground-Water Contamination at Puente Valley Operable Unit
	02/01/06	EPA to Oversee Field Work to Install Groundwater Cleanup System in the Puente Valley Area
	07/01/09	EPA to Install Pipeline & Treatment System for Groundwater Cleanup Program - English & Spanish
Records of Decision
		6/04/05 - Explanation Of Significant Differences ToThe 1998 Interim Record Of Decision Puente Valley Operable Unit
		Puente Valley Operable Unit, Interim Record of Decision, Volume 1, September 1998
Technical Documents
	10/01/08	Community Involvement Plan San Gabriel Valley Superfund Site Area 4 - Puente Valley Operable Unit

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Community Involvement

Public Meetings:

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Public Information Repositories

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Additional Links

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Contacts

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