Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Aerojet General Corp.
EPA #: CAD980358832
City: Rancho Cordova
Congressional District: 3
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 12/30/82
Final Date: 09/08/83
The Aerojet General Corporation site covers 5,900 acres near Rancho Cordova. The northeastern edge of the site is about 1/2 mile from the American River. Since 1953, Aerojet and its subsidiaries have manufactured liquid and solid propellant rocket engines for military and commercial applications and have formulated a number of chemicals. In addition, the Cordova Chemical Company operated chemical manufacturing facilities on the Aerojet complex from 1974 to 1979. Both companies disposed of unknown quantities of hazardous waste, including trichloroethene (TCE) and other chemicals associated with rocket propellants and various chemical processing wastes. Wastes were disposed of in surface impoundments, landfills, deep injection wells, leachate fields, and some were disposed of by open burning. Underlying the site are extensive 40 to 100 foot-deep dredge tailings, a remnant of past gold mining operations.
In 1979, volatile organic compounds (VOCs) were found off-site in private wells and in the American River in 1983. Perchlorate was found in drinking water wells off-site above the provisional reference dose range in January 1997. The communities potentially affected by this site are Rancho Cordova, population 61,911; Carmichael, population 61,762, Fair Oaks, population 30,192, and Gold River, population 7,912. Groundwater is used extensively throughout the Rancho Cordova area to supply municipal, domestic, industrial and some irrigation water. Public and private drinking water supply wells have been contaminated and wells contaminated above response levels have been closed. Aerojet continues to monitor drinking water supplies to assure compliance with drinking water standards. Lake Natoma and Alder Creek are nearby and are used for recreational activities. The American River is a drinking water source, which receives indirect discharges from Aerojet's facility and groundwater treatment systems under National Pollution Discharge Elimination System (NPDES) permits.
Contaminants and Risks
- Surface Water
- Soil and Sludges
Groundwater and surface water contain volatile organic compounds (VOCs) such as trichloroethene (TCE), perchloroethylene (PCE), 1,1-Dichloroethene, 1,1-Dichloroethane, 1,2-Dychloroethene, 1,2-Dichlorethane, 1,1,2-Trichloroethane, Carbon Tetrachloride, Vinyl chloride, Chloroform, and Freon-113 and other rocket propulsion waste products or components such as perchlorate and N-Nitrosodimethylamine (NDMA). VOCs are organic (carbon-containing) compounds that vaporize easily at room temperature. VOCs are commonly used in dry cleaning, metal plating, machinery degreasing, paint stripping, and as industrial solvents. Soils are contaminated with VOCs, perchlorate and metals including arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, nickel, and zinc. Potential health risks include: 1) drinking contaminated groundwater, and 2) for persons with access to Aerojet property or Areas 39, 40, 41 and the Inactive Rancho Cordova Test Site (IRCTS) drinking contaminated surface water or coming into direct contact with or accidentally ingesting contaminated soils. Contaminated drinking water wells above the response levels have been removed from service.
Who is Involved
This site is being addressed through Federal, State, and potentially responsible parties' actions.
Investigation and Cleanup Activities
Change in cleanup approach: The 1989 Partial Consent Decree (PCD) for Remedial Investigation and Feasibility Study (RI/FS) was modified 4/15/02 to allow the site to be divided into Operable Units. The RI is a report detailing the nature and extent of contamination and the FS describes alternatives to address the contamination. Dividing the site into Operable Units (OUs) allows Aerojet and the regulating agencies to prioritize investigation and cleanup work; and accelerate cleanup.
The cleanup approach for the site under the modified PCD is to control groundwater contamination with two OUs, then remediate soil and groundwater at source areas (an additional 5 OUs). In 2001 EPA completed the Record of Decision for the long term groundwater cleanup of OU-3, the first groundwater action. The full construction of this action has been completed and the effectiveness of the groundwater containment systems are being evaluated. Many portions of the groundwater actions for OU-5 have also been completed and are in operation. The integrated plans for OU-5 including a number of contaminated soil areas were presented to the public in August 2009, and the final decision was formalized in February 2011. The first source area OU (OU-6) has completed the RI/FS process and a Proposed Plan was issued on May 1, 2013. Upon implementation of cleanup for the five source OUs, a cumulative risk review will be done to determine any further action required for the site as a whole.
Interim Actions: Between 1983 and 1987, prior to the formal analysis and public process to select a long-term cleanup, five groundwater extraction and treatment (GET) facilities were installed as a barrier system, primarily to prevent further off-site movement of VOC contaminants. Each GET facility consists of a series of extraction wells and a groundwater treatment system to intercept contaminated groundwater before it moves off Aerojet property (GET A is in groundwater flow Zone 4, GET B is in groundwater flow Zone 3, GET D is in groundwater flow Zone 1, and GETs E and F in groundwater flow Zone 2). GETs E and F were combined in 1999 to provide for treatment of NDMA and perchlorate. GET E/F was further expanded in 2002 and in 2003 the discharge was diverted to the Buffalo Creek under an NPDES permit. GETs A and B discharge to Rebel Hill Ditch. GET A was moved to the GET B location in 2010. A sixth GET facility, the American River GET (AR GET) was placed in operation July 1998 to augment GET D VOC capture and discharges to Buffalo Creek.
As the long-term cleanup actions are determined through the RI/FS process culminating in a Record of Decision for each Operable Unit, any Interim Action is incorporated into the remedy selected.
Aerojet began a Time-Critical Removal Action in November 2009 to clean PCB- and metal-contaminated sediment from several drainage ditches and culverts in the Perimeter Operable Unit (OU-5) prior to weather conditions that could spread the contaminants. Final disposal of the 4,930 tons of soil was delayed by weather until the spring of 2010. EPA approved transfer of the soil to the Forward Class II landfill in Stockton. Aerojet submitted the final report on May 24 2010 and EPA finalized the Pollution Report completing the Removal Action the same day. EPA certified that Aerojet had fulfilled all requirements of the UAO to implement the Removal Action.
Entire Site: In 1983, with formal modification in 1998 and 2001, EPA ordered Aerojet to investigate the nature and extent of groundwater and soil contamination throughout the site with oversight by the U.S. EPA, the California Department of Toxic Substances Control (DTSC), and the Regional Water Quality Control Board (RWQCB). The investigation is phased to develop RI/FS reports for each individual OU, starting with OU-3 and OU-5 to ensure protectiveness from the groundwater contamination spreading beyond the property boundary.
Technology pilots are being conducted to assess in-situ bioremediation and other innovative technologies applicable to large scale groundwater remediation and methods to control dense non-aqueous phase liquids (DNAPL) and options available for DNAPL reduction.
Western Groundwater OU (OU-3): Studies to define the nature and extent of contamination of groundwater migrating from the western end of the Aerojet property were formally completed in 2001 when EPA signed a Record of Decision (ROD) specifying the selected groundwater cleanup plan for this part of the site.
Perimeter Groundwater OU (OU-5):In August 2002, the EPA and the State issued parallel orders to Aerojet to begin or expand critical work to achieve full containment of contaminated groundwater on the north and south side of Aerojet and prevent contamination from flowing off Aerojet's property. Aerojet was directed to conduct an RI/FS for the Perimeter Groundwater Operable Unit or OU-5 to address the groundwater and investigate 26 potential soil source areas located within Aerojet’s perimeter development plans. The RI/FS for OU-5 was submitted to the EPA's National Remedy Review Board October 6, 2005 for review of compliance with national policy.
Studies similar to those conducted for OU-3 for plumes emanating from the north and south boundaries of the Aerojet property for OU-5 were completed in June 2009, including an extensive site-specific study of the potential risks from VOC vapors to people living and working above the contaminated groundwater. EPA issued a Proposed Plan for the Perimeter Groundwater OU in August 2009. The public comment period was extended by request to October 1, 2009. On August 11, 2009, a public meeting was held to present the plan and take verbal comments at the City Hall of Rancho Cordova. The ROD was signed on February 15, 2011.
Boundary OU (OU-6) is the first of five source areas scheduled to be addressed by sequential RI/FS studies. The RI report was finalized in 2011, and the final FS report was issued in 2012. EPA issued a Proposed Plan based on the information in the RI/FS report in May 2013 with a public comment period of May 8, 2013 to June 7, 2013. On May 16, 2013, EPA received and approved a request to extend the public comment period to September 20, 2013. On July 22, 2015, EPA signed the Record of Decision for the Boundary Operable Unit (OU-6) and it is available in the "Document and Report" Section of the web site under Record of Decisions.
Cleanup plans for the remaining OUs will be presented for public comment as they are developed. An examination of the effectiveness, protectiveness and regulatory compliance of the remedies for the entire Aerojet Site will lead to a final site-wide cleanup plan once remedies for all of the individual OUs are selected.
The Proposed Plan for Western Groundwater (OU-3) was issued in November 2000 and public meetings were held December 7, 2000 and January 17, 2001. The EPA issued the ROD for OU-3 on July 20, 2001 and a Unilateral Administrative Order to Aerojet for the work on August 9, 2002. OU-3 will contain contaminated groundwater on the western side of Aerojet and restore the aquifer between the on and off-property control systems. There are fifteen Contaminants of Concern in OU-3 groundwater but the primary contaminants are TCE, perchlorate, and NDMA.
The Aerojet Record of Decision for the Perimeter Groundwater OU (OU-5) was signed on February 15, 2011 including a responsiveness summary to public comments received. The ROD selected an Interim Remedy for Groundwater and a final cleanup for the contaminated soil locations. The groundwater remedy will hydraulically contain the plume areas to prevent the spread of contamination, with additional pumping and treating to intercept and remove highly contaminated groundwater where possible. Within OU-5, there are 17 contaminants of concern identified although TCE, NDMA and perchlorate are the primary contaminants as in OU-3. In OU-5 there are four different groundwater areas and some of them require cleanup actions in other Operable Units to eliminate the contaminant source. We are considering this an interim groundwater remedy until the source areas are fully addressed. Most of the groundwater capture system is already in place and operating as part of the initial actions described above. The Soil Areas remedy is to excavate or otherwise clean the soil areas to levels protective for residential use. Fourteen contaminants of concern were identified in the soil areas, including metals and others that are not issues in groundwater. We recognize that there could be difficulty in achieving the desired cleanup levels in some of the soil areas, so the remedy includes a combination of engineering controls (such as intercepting soil vapor) and Institutional Controls (limiting the land use) as necessary.
The Aerojet Record of Decision for the Boundary OU (OU-6) was signed on July 22, 2015 including a responsiveness summary to public comments received. The public comment period for the OU-6 proposed plan was from May 8, 2013 to June 7, 2013, with an extension to September 20, 2013. EPA presented the Proposed Plan and recorded oral comments at a public meeting on May 15, 2013. The selected OU-6 remedies include removal of impacted source materials to reduce contaminants to levels to allow for restricted or unrestricted use to protect the public and environment. The methods include: excavation and offsite disposal of contaminated soils with concentrations above levels acceptable for unrestricted use, or use of soil vapor extraction system to remove volatile organic compounds (VOCs); and soil flushing (with air stripper) to remove contaminants from soil in areas where risks to groundwater are high, but removal is infeasible due to depth. These methods prevent contaminants from moving from these sources to groundwater at concentrations that may impair beneficial use. Also, the ROD includes Engineering Controls to protect the integrity of cap and mitigation systems, and Institutional Controls to restrict unacceptable land uses, require environmental evaluations and protect engineering controls. The ROD is available in the Documents and Report section of this web site and at the site information repositories listed below.
The final groundwater extraction and treatment system planned for the Western Operable Unit (OU-3) began operating in May 2010. At GET H (Area 1), the treatment plant and all extraction wells are operating. At GET J (Area 2), all ten extraction wells are in service. Combined GET E/F with 21 extraction well locations is fully operational. GET K (Area 3) extraction wells, pipelines and treatment systems in Rancho Cordova were completed and operational in 2009. The GET L (Area 4) Bajamont Way Treatment plant is across the American River from the Aerojet Facility in Carmichael and has been fully operational since 2008. GET L-A is also across the American River in Ancil Hoffman Park, a county park and golf course in the City of Carmichael. Treated water is used for irrigation of the County's golf course. EPA has been coordinating with Aerojet to design and oversee preparation of a rigorous Effectiveness Evaluation of the full OU-3 remedy, with a major working sessions held in 2010 and planned for 2011. Evaluation of the effectiveness of the systems will be conducted by EPA and the State until satisfactory containment of the contamination can be demonstrated. A formal public review of the remedy will be conducted by EPA every five years until all cleanup objects are attained. These Five-Year Reviews will examine ongoing work throughout the Aerojet Site, not only one Operable Unit.
The groundwater extraction and treatment system for the Perimeter Groundwater Operable Unit (OU-5) is close to full operation. Additional design and construction of extraction systems will proceed under orders from EPA and the State. The water treatment systems have been constructed, although treatment systems may be modified or expanded as needed in the future. Planning and cleanup are complete in several of the soil areas and others are proceeding rapidly with EPA oversight. The OU-5 groundwater containment is being examined In conjunction with the effectiveness evaluation of the OU-3 groundwater remedy.
Cleanup Results to Date
Nine groundwater extraction and treatment systems "GETs" are operating throughout the Aerojet site: ARGET, GET A/B, GET D,, GET E/F, GET H-A, GET J, GET K-A, GET L-A and GET L-B. Together they remove over 20 million gallons of contaminated groundwater each day on average.
Through the end of 2014, all the groundwater extraction and treatment systems at Aerojet in OU-3 and OU-5 have treated a cumulative total of 137 billion gallons of groundwater and removed more than one million pounds of chemical contaminants.
Western Groundwater OU-3: The Western Groundwater Operable Unit is containng the contaminated groundwater on the western side of Aerojet and eventually will restore the aquifer. All of the planned extraction wells and treatment systems are operating. Under the Unilateral Administrative Order that EPA issued to Aerojet to complete construction of the Western Groundwater remedy, Aerojet publishes a notice to the public annually, showing the current maximum extent of groundwater contamination in OU-3.
The Five-Year Review Report (FYR) was completed on September 22, 2016. The FYR covered the Western Groundwater Operable Unit (OU-3) and Perimeter Groundwater OU (OU-5), which are the only two OUs with remedies in place.
At this time, EPA has deferred making a protectiveness determination for OU-3 and OU-5 until further information is obtained. Due to changes in vapor intrusion assessment procedures and changes in toxicity, potential vapor intrusion exposures are unknown. Further information will be obtained by reassessing the vapor intrusion pathway. Vapor intrusion pathway is the means by which volatile chemicals in shallow groundwater or soil may enter into future buildings or dwellings and affect indoor air quality.
EPA expects that these investigation actions will take approximately one year to complete, at which time a protectiveness determination will be made.
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.
The PRP for this site is the Aerojet Rocketdyne, Inc.
Documents and Reports
Public Meetings: Aerojet Community Advisory Group
Since March 22, 2001, the Aerojet Community Advisory Group (CAG) has met with EPA, State regulatory agencies, Aerojet Rocketdyne and interested stakeholders to provide information on the investigation and cleanup program of the Aerojet Corporation Superfund Site in Rancho Cordova, CA. A Superfund Community Advisory Group (CAG) is made up of members of the community and is designed to serve as the focal point for the exchange of information about the Site and to involve the public in the cleanup process. The Aerojet CAG Chairperson is Janis Heple and can be contacted at email@example.com. The most recent notes from the Aerojet CAG meetings are located in the “Documents and Reports” Community Involvement Section above. If you would like to attend the Aerojet CAG meeting, see below the 2017 meeting schedule:
Aerojet CAG Meeting Information
Location: Rancho Cordova City Hall
2729 Prospect Drive (American River South Room)
Rancho Cordova, CA 95670
Dates: Wednesday, January 18, 2017 - Meeting Occurred and Notes Above
Wednesday, March 15, 2017 - Meeting Occurred
Wednesday, May 17, 2017 - Cancelled
Wednesday, July 19, 2017
Wednesday, September 20, 2017
Wednesday, November 15, 2017
Boundary Operable Unit 6 Proposed Plan Comment Period
EPA held a proposed plan public meeting on May 15, 2013 at 7pm at the Rancho Cordova City Hall, 2729 Prospect Park Dr., Rancho Cordova. On May 16, 2013, EPA received and approved a request to extend the comment period to September 20, 2013. Transcripts are provided in the Documents and Reports - Community Involvement Section. The Record of Decision was signed for OU-6 on July 22, 2015 and includes formal response to all public comments received. It is posted in the Documents and Records - Record of Decision Section above and a copy sent to the local site repositories listed below. A notice was published in the Sacramento Bee newspaper on September 28, 2015.
Western Groundwater (OU-3) Proposed Plan Public Meeting
The EPA held two meetings for public comment on the Western Groundwater Proposed Plan, one on December 7, 2000, and the second on January 17, 2001. Transcripts are provided in the Documents and Reports - Community Involvement section. Formal Response to all public comments received are in the Record of Decision for OU-3, in the Documents and Records - Record of Decision section.
Perimeter Groundwater (OU-5) Proposed Plan Public Meeting
The EPA held one meeting for public comment on the Perimeter Groundwater Proposed Plan, August 11, 2009. EPA's Proposed Plan Presentation at that meeting and meeting transcripts are provided in the Documents and Reports - Community Involvement section. Formal Response to all public comments received are in Appendix A of the OU-5 Record of Decision, in the Documents and Records - Record of Decision section.
Public Information Repositories
The public information repositories for the site are at the following locations:
Sacramento Central Library
828 “I” Street
Sacramento, CA 95814
CA State University, Sacramento,
2000 State University Drive Sacramento, CA 95819-6039
EPA Site Manager
Mail Code SFD-7-1
75 Hawthorne Street
San Francisco, CA 94105
US EPA Region 9
Mail Code SFD-7-3
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD-6-3
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
James Rohrer, DTSC
11020 Sun Center Dr. Suite 200
Rancho Cordova CA 95670
California Department of
Toxic Substances Control
8800 Cal Center Dr.,
Sacramento, CA 95826-3200
Engineering Manager, Site Remediation
11260 Pyrites Way, Suite 125
Rancho Cordova, CA 95670
After Hours (Emergency Response)