Site Mitigation & Restoration Program

We protect and maintain California’s land and places
by setting strict standards for land restoration and cleanup

Aerojet Rocketdyne Chino Hills

Welcome to the website for the investigation and cleanup of environmental contamination at the Aerojet Rocketdyne Chino Hills Facility (AR).

Investigation and cleanup activities at AR include investigations and cleanup of chemical contamination and Munitions and Explosives of Concern (MEC) and surface and ground water monitoring.

This website is designed to provide public access to information regarding the various investigation and cleanup activities that are completed or under way at the AR site. We hope this dedicated site serves as your initial AR communications vehicle and provides the information you’re looking for. We welcome your suggestions to enhance this website.

About the AR Chino Hills Facility

The former Aerojet Rocketdyne Chino Hills Ordnance Facility is located at the end of Woodview Road in the City of Chino Hills (San Bernardino County). The entire property that has been under investigation and cleanup consists of 800 acres, of which Aerojet owns 580 acres and includes 220 acres leased by AR as a facility buffer and collectively referred to as “the Site.” The operating facility, or specific areas within it, are referred to as “the facility.” The Vellano residential development/golf course and Chino Hills State Park border the site.

History of the Aerojet Rocketdyne Former Chino Hills Ordinance Facility

Aerojet General Corporation (now named Aerojet Rocketdyne, Inc., referred to as”Aerojet”) operated the facility from 1954 through November 1995. It began operations as a small ordinance testing facility. Beginning in 1974, operations primarily involved research, development,assembly and testing of munitions, including 25 mm and 30 mm high-explosive incendiary projectiles, armor-piercing incendiary projectiles composed in part of depleted uranium, and fuzes.

The munitions were assembled in the northwestern portion of the facility and random samples of the assembled munitions were tested in the central portion of the facility to verify compliance with U.S.Military requirements and specifications. Projectiles were test fired in small box canyons within the facility, utilizing fixed guns firing into fixed targets. Throughout the years of ordnance assembly and testing, explosive and propellant wastes were generated. These wastes were often handled and treated at the facility, in accordance with state and federal requirements in place at the time.Ordnance that did not meet quality control specifications was treated or destroyed on the facility in designated treatment areas.


In 1992, Aerojet approached DTSC to discuss closure activities for the facility, with a goal to allow for future, unrestricted use of the property. Two separate projects were initiated. The first was for closure of the Open Burn/Open Detonation units (OB/OD), which operated under Resource Conservation and Recovery Act (RCRA) interim status from 1965 through 1992. In 1993, DTSC approved the closure plan for cleanup of the OB/OD units and Aerojet began implementing that plan in 1994. In 1994, Aerojet and DTSC entered into a separate Administrative Agreement on Consent for corrective action involving a site investigation, human health and environmental assessment, selection of a cleanup option, and implementation of corrective measures for the remainder of the Site.


In 1994, pursuant to the administrative agreement on consent, DTSC and Aerojet began the environmental investigation to determine the nature and extent of contaminants present at the Site and define cleanup options. In 1995, Aerojet divested its ordnance business and ceased all business operations at the Chino Hills facility. Activities since then have focused solely on site investigation and remediation. Site remediation activities were voluntarily initiated by Aerojet under the oversight of DTSC. The environmental investigation was completed in 1999. Contaminants that were found included MEC (both exploded and unexploded projectiles and fragments), explosive compounds, metals, perchlorate in soil and subsurface water, and depleted uranium in soil and subsurface and surface water. Cleanup options were developed for the MEC, metals and perchlorate and presented to the community through a public process, and a cleanup remedy was selected and approved in November 2000.



Cleanup activities and additional studies were ongoing through this period, and included:Corrective Measures for Solid Waste Management Units and Areas of Concern. This work was completed in 2002 following DTSC-approved work plans, and a draft report of the completion of corrective measures was submitted to DTSC in November 2003. Remaining corrective measures for SMWUs and buildings were completed in 2007. A human health and environmental assessment was originally completed in 1999, with follow-up evaluation in 2006 and 2008 after completion of DTSC-approved Corrective Measures. DTSC approved the Corrective Measures Completion Report (and Addendum), indicating that chemical contamination and materials of concern have been removed to levels presenting no significant health risk based on current land use in 2009.

Cleanup activities for Depleted Uranium (DU): A final report, including a risk assessment, on achieved cleanup levels was submitted in 2003 and an independent confirmatory California Department of Public Health (DPH) review was conducted in 2007-2008. Following this review, DPH approved the decommissioning and decontamination (D&D) activities for unrestricted use of the property and terminated the radioactive materials license.

Cleanup of the Open Burn/Open Detonation Unit and third-party quality assurance activities related to that cleanup was completed from 2003-2006. DTSC certified closure of the unit in 2009.


DTSC approved a two-phased approach for completion of the Corrective Measures Study (CMS) to address residual MEC for the entire Site in 2013 and evaluate appropriate final cleanup actions. Phase one addressed portions of the facility known as Management Areas 1 and 2. AR developed a proposed cleanup plan, called a draft CMS, and submitted it to DTSC in 2013. This draft CMS focuses on a goal of achieving a “clean closure” designation for these portions of the Site. In compliance with the California Environmental Quality Act (CEQA), DTSC prepared a draft initial study and is proposing a “Negative Declaration,” which means the proposed cleanup actions for Management Area 1 will not have a significant or adverse effect on human health or the environment (no cleanup actions are needed for Management Area 2). Phase two will address Management areas 3 and 4 will be addressed in a subsequent CMS. 

DTSC reviewed and approved the revised draft CMS dated July 2015, which was provided for public review and comment. Subject to final approval, work will likely begin following a DTSC approved work plan. DTSC is requiring additional sampling of the surface and subsurface water at the site. DTSC is requiring Aerojet to conduct a comprehensive site wide risk assessment for both human health and ecological risk, based on unrestricted use of the site. Depending on the results of the risk assessment, DTSC may require additional cleanup of contamination in soil and or water. 

Regulatory Oversight

Approximately 100,000 private and public facilities generate one or more of the 800-plus wastes considered hazardous under California law. The Department of Toxic Substances Control (DTSC) regulates those who handle hazardous waste, cleans up existing contamination and looks for ways to reduce hazardous waste produced in California.

In 1994, AR entered into a Consent Order with DTSC to conduct the investigation that would lead toa risk-based cleanup, in accordance with DTSC’s statutory authority.

Frequently Asked Questions

Q. What kind of materials have been found and removed from the Site?

A. Cleanup has focused on three areas: Solid Waste Management Units, Open Burn/Open Detonation Units, and Depleted Uranium (DU) test areas. The primary materials of concern are chemicals found in explosives, which include RDX, HMX, and perchlorate. Depleted uranium was used in the military ordnance that was tested. Some unexploded ordnance, known as Munitions and Explosives of Concern (MEC) was also found. 

Q. Has all the ordnance in the area been removed?

A. A great deal of work has been done to remove these materials, including two separate screenings of the OB/OD Unit and an independent third party Quality Assurance (QA) analysis. The analysis did not identify any quality issues regarding the past munitions investigations. However, DTSC has determined that there is concern of residual ordnance or MEC present at portions of the Site because of topographical constraints and limitations in technologies used for locating and removing ordnance. Aerojet Rocketdyne, in cooperation with DTSC, has developed a cleanup plan to ensure long term public health and safety. With this in mind, it is important that until completion of all ongoing cleanup activities, the public obey the “unauthorized personnel keep out” signs surrounding the Site. 

Q. Why hasn’t the cleanup work been completed yet?

A. In accordance with the approved Corrective Action process, all cleanup activity has been conducted under the oversight—and pursuant to the approval—of DTSC. While a substantial amount of cleanup work has been conducted at the Site and several areas within the Site have achieved closure status (no further action required), additional corrective and remedial (cleanup) activity is necessary to ensure current and future occupants are not at risk from residual MEC.  DTSC also wants to ensure that there is no significant risk from chemical contamination or uranium in soil or water. 

Q. What will the future cleanup activities involve?

A. A Phase 1 Corrective Measures Study for Management Areas 1 and 2 was submitted to DTSC and made available for public review and comment. Under this plan, Corrective Measures (CMs) will be implemented in portions of Management Area 1 to address concerns of potential residual MEC and allow for unrestricted use of this portion of the Site. The recommended CMs include removal of suspect soil and additional ordnance sweeps. This work will take one to two months to complete. MEC construction support would also be provided during future construction activities in areas with known or suspected residual MEC. No additional measures are needed in Management Area 2 because this portion of the Site was determined to be suitable for unrestricted use in the Phase 1 CMS and approved by DTSC. 

Q. When will final cleanup be complete?

A. At this time, it remains too early to predict when final Site closure will be achieved. DTSC has already approved a two-phased approach for completion of the CMS for MEC for the entire Site. Consistent with that approval, Aerojet has developed a proposed cleanup plan for the first phase CMS for Management Areas 1 and 2, subject to public review and comment. Pending approval, work on Phase 1 will likely begin in late 2017 and is estimated to take one to two months to complete. In the meantime, Aerojet Rocketdyne will also begin development of the Phase 2 CMS for Management Areas 3 and 4.  DTSC is also requiring Aerojet to conduct additional surface and subsurface water sampling to ensure that there is no chemical or uranium contamination present that would present a significant health risk.  A comprehensive human health and ecological risk assessment will be conducted based on the data collected.  Depending on the results of the risk assessment, DTSC may require additional chemical cleanup in soil and or water. 

Q. What do I do if I find something that I think is leftover or unexploded ordnance?

A. See our Community Safety web page for information regarding leftover or unexploded ordnance. 

Q. Has my health been affected by previous operations at the Site?

A. Risks to public health are unlikely because the Site has been closed to the public and there are no known complete pathways of exposure to any chemicals of concern. Cleanup activities completed at the Site have further reduced the potential for public health risk. Under the supervision of DTSC, Aerojet conducted a Health Risk Assessment that evaluated the chemical toxicity of uranium remaining in Site soils. The Corrective Measures Completion Report (and Addendum) also evaluated the chemical toxicity of other compounds remaining in Site soils. These assessments found that levels of residual compounds remaining in Site soils were below thresholds that would have a significant effect on health based on the current land use, and therefore no further action was required. In addition, the California Cancer Registry conducted three cancer assessments for Chino Hills. None found any excess in the cancer occurrence in Chino Hills. The assessments also reported fewer childhood cancer cases than what would normally be expected in a community with the same size and demographic makeup as Chino Hills. These assessments are available for review in the Public Information Repositories for the Site. Aerojet will be required to conduct a comprehensive risk assessment prior to any change in land use.

For the solid waste management units, more than 2,200 soil and water samples were collected and analyzed with results showing there were no harmful levels of chemicals in surface waters, nor were any chemicals moving off site at concentrations that posed a human health or environmental risk. Elevated levels of explosive compounds were detected in subsurface water beneath two solid waste units.  DTSC is requiring Aerojet to conduct additional surface and subsurface water sampling to ensure that there is no chemical or uranium contamination present that would present a significant health risk. A comprehensive human health and ecological risk assessment will be conducted based on the data collected. 

Q. Is my drinking water safe?

A. The subsurface water under the Site is not a source of drinking water. DTSC is requiring Aerojet to sample surface and subsurface water to ensure that there is no contamination present that could present a health risk.  Drinking water is provided by the City of Chino Hills and is tested regularly to ensure it meets all federal and state drinking water standards before it is delivered to the community. For questions about drinking water, contact the City of Chino Hills Public Works Department at 909-364-2800 or 909-364-2860 (after-hours). 

Q. What are the future plans for the Site after cleanup?

A. That decision has yet to be made. While the goal of the cleanup is to allow for the unrestricted future use after cleanup is complete in Management Area 1, this is not a predetermined outcome. Aerojet Rocketdyne must follow the process and requirements specified by DTSC, and only upon completion and a thorough evaluation of the cleanup by DTSC and consultation with the City of Chino Hills will the potential re-use be determined. Future land use will be determined by Aerojet Rocketdyne and the city of Chino Hills, not by DTSC. 

Q. How can I get additional information regarding this site?

A. Additional information is available by contacting Stacey Lear, DTSC Public Participation Specialist, at 714-484-5354, or Robert Romero at 714-484-5476.