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The site was historically used to test rocket engines for NASA and the military, and to perform non-military nuclear energy research at Department of Energy’s (DOE) Energy Technology Engineering Center (ETEC), for example, leading-edge nuclear power, solar and energy-efficiency technology development.

The Santa Susana Field Lab’s 2,850 acres are divided into four administrative areas. �Ӱ���Ƶ acquired 2,398 acres from Rocketdyne in 1996 when it purchased Rockwell's aerospace and defense unit. The Department of Energy (DOE) owns several buildings on the 90 acres of �Ӱ���Ƶ property it leased and the U.S. Government owns 452 acres that are administered by the National Aeronautics and Space Administration (NASA).

Santa Susana, CA is a vast hilltop natural area dominated by sandstone cliffs featuring oak woodlands, scrub and meadows, with valley and mountain vistas. Plant and animal species thrive at the Santa Susana Field Lab, including deer, bobcats, coyotes, cougars and raptors. A few decommissioned rocket engine test stands and other buildings still dot the landscape. Nearly 90% of historical buildings have been removed as operational activity at the Department of Energy's Energy Technology Engineering Center was phased out in 1988 and rocket engine testing ended in 2006. Environmental and community groups and universities use the land for environmental research, restoration and recreation. �Ӱ���Ƶ hosts frequent bus tours and guided hikes to share the Santa Susana’s historical significance and cleanup progress.

Yes. Santa Susana, CA – with its sandstone cliffs, oak woodlands, meadows, hills and streams – provides a rare and vital habitat and a crucial wildlife linkage in the Simi Valley area of Southern California. The site has a unique history of Native American use and aerospace technological achievements. Because the Simi Hills site has these characteristics, in 2017, the North American Land Trust recorded a conservation easement to permanently protect the land as open space habitat.

�Ӱ���Ƶ has partnered, and will continue to partner, with established organizations that share its open space vision. In addition, leading universities are engaged in environmental research at �Ӱ���Ƶ Santa Susana. The National Park Service is also studying the possibility of including the site in the Santa Monica Mountains National Recreation Area as part of its Rim of the Valley study.

As the holder of the conservation easement, North American Land Trust (NALT) monitors activities at the Santa Susana Field Laboratory to ensure the prevention of development and preservation of natural and cultural resources. NALT also has the authority to enforce the land use restrictions in court.

The conservation easement does not affect the responsibility of �Ӱ���Ƶ, the Department of Energy or NASA to fulfill their respective cleanup requirements. It ensures there is no confusion about the future use of the Santa Susana Field Laboratory property. Future land use is critical in determining the level of cleanup necessary to protect human health and the environment. The conservation easement legally secures the future of the Simi Valley site as open space habitat. It ensures that, regardless of zoning or the desires of any future land owner, the site will never be used for residential or agricultural purposes. We remain committed to completing a cleanup that fully protects human health and the environment, consistent with the future use of the Santa Susana, CA property as open space habitat.

The conservation easement provides certainty that the only legally permitted future use of nearly 2,400 acres of the Santa Susana Field Lab, now and forever, is open space habitat. The Environmental Impact Report (EIR) should only consider cleanup scenarios consistent with that future use.

The Santa Susana conservation easement is recorded in the Official Records of Ventura County and permanently "runs with the land," which means that it lasts and binds the Simi Valley property forever, regardless of who owns the property.

Numerous parties have the right to enforce the provisions of the conservation easement recorded over �Ӱ���Ƶ Santa Susana. In addition to �Ӱ���Ƶ and the land trust easement holder (North American Land Trust) being able to enforce the restrictions on any current or future land owner or occupant of the Simi Hills property, the conservation easement also specifically provides that the California Attorney General and "any governmental authority with jurisdiction over the Property" are able to enforce the conservation easement. That would include not only the California Attorney General’s Charitable Trust Section, whose mission is to investigate and bring legal actions against charities that misuse charitable assets, but also agencies like DTSC, the LA Regional Water Quality Control Board, and Ventura County. As such, �Ӱ���Ƶ’s conservation easement is significantly stronger than other restrictive covenants or land use restrictions that the State of California enters into with landowners to restrict future property use at contaminated sites.

The Santa Susana Field Lab conservation easement clarifies the future land use so that appropriate cleanup decisions can proceed. We have publicly stated for over a decade that we will clean up and restrict �Ӱ���Ƶ Santa Susana to ensure it is preserved as open space to protect the important habitat, cultural and historical values in the Santa Susana Mountains. The conservation easement makes �Ӱ���Ƶ’s commitment legally binding. We hope the conservation easement will reassure the public, and all who are committed to the preservation of the invaluable natural and cultural resources at the field lab, of our commitment to completing a cleanup that fully protects human health and the environment for the site’s future as open space habitat.

No. On April 24, 2017, �Ӱ���Ƶ recorded a conservation easement in favor of North American Land Trust (NALT) to permanently preserve and protect �Ӱ���Ƶ’s nearly 2,400 acres at the Santa Susana site. The Settlement Agreement does not affect the validity of the conservation easement. �Ӱ���Ƶ maintains that the Conservation Easement is legally enforceable, in perpetuity, is consistent with the land’s zoning as open space, and is fully effective, regardless of the Settlement Agreement. NALT, an established and respected land trust, holds numerous conservation easements, preserving property nationwide. The conservation easement over �Ӱ���Ƶ’s land at Santa Susana seeks to:

• Conserve and protect �Ӱ���Ƶ’s property from specified development or uses.
• Ensure approximately 2,400 acres of land in Ventura County will remain open space habitat, prohibiting residential, agricultural and other uses.
• Forever protect the land, which is a part of the Regional Wildlife Corridor and Simi Hills Critical Wildlife Passage Area in Ventura County’s General Plan and Non-Coastal Zoning Ordinance
• Provide for deference to the DTSC’s and the Los Angeles Water Board’s regulatory requirements for cleanup.

�Ӱ���Ƶ’s property at Santa Susana will remain as open space. As a compromise to resolve prior disputes and accelerate to cleanup and subject to the terms of the Settlement Agreement, �Ӱ���Ƶ has agreed not to challenge DTSC’s selection of a remedy to a cleanup level, up to and including a “Resident with Garden” exposure scenario. Although �Ӱ���Ƶ would incur more cost to excavate and remove more soil than under other exposure scenarios, by agreeing in advance to a range of cleanup scenarios it will avoid years of disputes and litigation, and it will be able to accomplish the soil cleanup more quickly in a manner that is also protective of surface water and groundwater, which is better for the community, public health and the environment. In addition, the protection of cultural and biological resources during cleanup will be a priority. Regardless of the cleanup standard selected, the recorded Conservation Easement for the �Ӱ���Ƶ property states that the property may not be used for residences or gardens.

No, the Conservation Easement provides that the approximately 2,400 acres of �Ӱ���Ƶ property at Santa Susana will remain open space habitat and prohibits residential, agricultural and other uses.

No. Even though the land use covenant restricting consumption from �Ӱ���Ƶ’s cleanup areas will be removed once the groundwater cleanup has taken place, the Conservation Easement prohibits human consumption of surface water and groundwater at the �Ӱ���Ƶ property in perpetuity.

Current zoning would allow residential development (i.e., one house (and one ancillary dwelling) on the 2,400 acres of �Ӱ���Ƶ land at Santa Susana). Any proposal to rezone the site to denser residential use would require compliance with the relevant land-use regulations and ordinances of Ventura County, including the zoning code and general plan. Additionally, changing the zoning to a more intensive use would likely require a vote by Ventura County residents pursuant to Ventura County law (e.g., Save Open Space & Agricultural Resources (SOAR) initiatives).

�Ӱ���Ƶ and DTSC, in coordination with the appropriate regulatory agencies and Tribal Representatives, will assess potential impacts on ecological, historic and cultural resources as part of the final remedy decision. DTSC may apply exceptions to the selected cleanup standard to preserve biological and cultural resources.

The comprehensive framework set forth in the two agreements provides �Ӱ���Ƶ with a clear process, schedule and criteria for future decision-making at the Santa Susana site in order to accelerate cleanup, reduce the potential for technical disputes and establish a process to resolve them quickly, and avoid delays due to potential litigation.

Last year, a well-known and respected polling firm in California conducted a poll on our behalf in order to gain insight into the public’s understanding of �Ӱ���Ƶ’s investigation and cleanup activities at Santa Susana, including �Ӱ���Ƶ’s settlement agreements with the State.

In a sample survey of more than 5,000 voters in Ventura and Los Angeles counties who live near the site, the poll found overwhelming support for the Agreement, with 84% of those surveyed expressing support. This research gives us insight into the local community’s understanding of our recent settlement agreement with DTSC and will assist us in keeping the public informed of our efforts to restore and preserve the site.

�Ӱ���Ƶ anticipates demolishing its remaining buildings in Area IV when the Physicians for Social Responsibility litigation is resolved.

In 2007, �Ӱ���Ƶ, NASA and the DOE signed a comprehensive cleanup agreement (“2007 consent order”) with the Department of Toxic Substances Control (DTSC). �Ӱ���Ƶ is committed to completing a cleanup of the Santa Susana Field Laboratory that is fully protective of both human health and the environment, consistent with the field lab’s future as open space habitat. �Ӱ���Ƶ continues to meet all of its obligations to implement the 2007 consent order. Here are key steps in the process:

• The DTSC issues a certified, final site-wide Programmatic Environmental Impact Report (EIR)
• DTSC approves the investigation reports previously submitted by �Ӱ���Ƶ
• �Ӱ���Ƶ is preparing risk assessment reports for DTSC approval
• When risk assessment is approved, �Ӱ���Ƶ will prepare a corrective measure study for DTSC approval
• When corrective measure study is approved and finalized, DTSC will issue a statement of basis outlining the final cleanup plan
• �Ӱ���Ƶ continues long-term groundwater cleanup and monitoring.
• �Ӱ���Ƶ completes soil cleanup.

�Ӱ���Ƶ secured a conservation easement that permanently preserves nearly 2,400 acres of �Ӱ���Ƶ-owned land at Santa Susana as open space habitat. After the cleanup, Santa Susana, CA will continue to be a place where Santa Susana mountain lions roam free, cultural artifacts remain undisturbed and oak woodlands have the opportunity to thrive.

Yes. We remain committed to a cleanup of the Santa Susana Field Laboratory that is fully protective of human health and the environment, consistent with the land’s future use as open space habitat. Our cleanup will protect everyone who visits Santa Susana for recreational purposes and our neighbors in the surrounding community, as well as preserve unique wildlife habitat and protect important Native American cultural resources.

�Ӱ���Ƶ recorded a conservation easement that permanently preserves nearly 2,400 acres of �Ӱ���Ƶ-owned land at the Santa Susana Field Laboratory as open space habitat. This easement ensures there will never be residential or agricultural development of the Simi Hills site.

Based on extensive data collected over decades, there are no levels of contaminants from Santa Susana that would pose a risk for off-site gardens or for residents using those gardens now, and in the future. In an April 2013 letter to the Mayor of Simi Valley, the DTSC stated, "To date we have not found evidence of off-site contamination from SSFL that would pose a risk to human health or the environment."

The reference in �Ӱ���Ƶ’s report submitted to DTSC that included an estimate for a lifetime Simi Valley cancer risk of one in three is a hypothetical risk prior to cleanup and is primarily attributable to naturally occurring arsenic. The hypothetical risk following cleanup at this location will be 1 in 1 million or less, a point clearly described in �Ӱ���Ƶ’s report. This calculation is just one among many that are considered in assessing the site and setting the ultimate cleanup level, and it is misleading to focus just on this calculation. The most important fact for the public to understand is that �Ӱ���Ƶ remains committed to completing a cleanup that is fully protective of both human health and the environment, consistent with the land’s future use as open space habitat.

With regard to the risk calculation referenced above, there are two critical points that must be understood to properly interpret this calculation and comprehend what it means, and what it doesn’t mean.

Assumption #1: The calculation assumes that no cleanup will ever be done. Fact: �Ӱ���Ƶ will perform a cleanup that is fully protective of human health and the environment, consistent with the land’s future use as open space habitat.

Assumption #2: The calculation assumes that a person will live on the site and consume produce from a backyard garden. Fact: No one will ever live on �Ӱ���Ƶ’s portion of Santa Susana in the Simi Hills. North American Land Trust holds a conservation easement that permanently preserves nearly 2,400 acres of �Ӱ���Ƶ-owned land at Santa Susana as open space habitat.

Future land use at the Santa Susana Field Laboratory is controlled by the 2017 conservation easement, not zoning. Under the conservation easement, no agricultural use for human consumption will ever occur on the nearly 2,400 acres at �Ӱ���Ƶ Santa Susana.

Following the cleanup at the Santa Susana Field Laboratory, contaminants from historic site operations that remain on �Ӱ���Ƶ’s property will be at or below levels that meet regulatory requirements and standards for property used as open space habitat.

The U.S. EPA conducted an exhaustive of Area IV between 2009 and 2012. The EPA described the survey as, “one of the most robust technical investigations ever undertaken for low-level radioactive contamination.” The results of the survey will help guide remediation efforts in Area IV.

According to the EPA:

• “In general, EPA found elevated radiation levels in the areas where we expected to find them, isolated to a number of former process or disposal areas.”
• “Level of radiation throughout most of the Area IV study area was lower than the offsite background locations.”
• “This survey resulted in the discovery of several areas of elevated radiation levels, but none posed a health risk to personnel.”
• As part of the survey, the EPA took 3,735 soil samples and conducted over 128,000 separate analyses. In summary, the radiation levels found were limited and localized to certain former process and disposal areas. These results are in line with what would be expected for a facility of this type, which operated for many decades. No (0%) samples exceed the EPA acceptable risk range for open space land use.

EPA Radiological Characterization Study Results fact sheet

A 2007 that compiled existing off-site data found no evidence of offsite radiological contamination. In an April 2013 letter to the Mayor of Simi Valley, the DTSC stated, “To date we have not found evidence of off-site contamination from SSFL that would pose a risk to human health or the environment.” in areas such as the Brandeis-Bardin Institute, Santa Susana Knolls, Moorpark and beyond. More recently, that “DTSC has not found any evidence that contamination from [historical] operations at SSFL has posed or would pose a threat to human health or the environment outside the SSFL site boundaries.”

No. Since 1990, numerous studies conducted by government agencies, university researchers and others have examined cancer rates in the communities surrounding Santa Susana. It is not unusual for multiple studies to be conducted and come to different conclusions, which is why one must look at all of them. Taken together, the studies do not support a link between incidences of cancer and past operations at the Santa Susana Field Laboratory (SSFL).

The two most recent studies were performed by Professor Lewis Morgenstern of the University of Michigan and Professor Thomas Mack of the University of Southern California Keck School of Medicine.

A 2007 study by Professor Morgenstern concluded, “The results from this study suggest little or no association between residential distance from SSFL and the incidence of all cancers or the group of (radio-sensitive) malignancies thought to be affected by ionizing radiation. There was, however, a weak positive association during both follow-up periods between distance from SSFL and the group of (chemo-sensitive) malignancies thought to be affected by exposure to chemicals used at Rocketdyne.” The study further concluded, “Furthermore, we have no direct evidence that the associations we observed, even if they reflect real differences among the three regions, necessarily reflect the effects of environmental exposures originating at SSFL.”

A 2014 study by Professor Mack concluded, “No evidence of measurable offsite cancer causation occurring as a result of emissions from the SSFL was found. Further, no evidence of any cancer causation by any environmental factor was found.” Dr. Mack presented his findings at a DTSC public meeting in April 2014.

An overview of epidemiological and community health studies can be found here.

It is not true that 300 times permissible concentrations were released during the Sodium Reactor Experiment accident. Many people have made various statements about the 1959 Sodium Reactor Experiment incident using assumptions that are not supported by facts and data.

What we do know is the incident occurred at a time when the area around the Santa Susana Field Laboratory was still sparsely populated. Records were kept of the levels that were released and used to calculate potential exposure dose. The total radiation doses for the two month period following the SRE accident were 0.099 millirem for a hypothetical person at the Santa Susana site boundary, and 0.018 millirem for a hypothetical person at the location of the nearest resident in 1959 (1.33 miles away).

These doses are a fraction of the permissible exposure level in 1959, and today’s more restrictive federal limits, including the Nuclear Regulatory Commission and Department of Energy exposure limits for nuclear facilities (100 millirem/year) and the U.S. EPA limit for airborne emissions (10 millirem/year). Nuclear energy operations at Santa Susana ended decades ago. The SRE accident has been the subject of extensive study and commentary. Here is some additional information about the incident:

Department of Energy SRE Workshop

No, there were no “secret releases of radiation” at the Santa Susana Field Laboratory. Radiation releases were monitored, measured and documented in compliance with federal regulations. The Santa Susana Field Laboratory continually monitored the site for potential releases and reported the results of its monitoring. The results of this sampling were documented in annual monitoring reports.

Copies of annual site environmental reports for Area IV of Santa Susana Field Laboratory from 1955 through 2014 are available on the .

Barrels of sodium and other chemicals were part of hazardous waste disposal in the Simi Valley site’s Area IV Burn Pit during the 1950s, 60s and 70s in compliance with existing regulations at the time. Subsequent site investigations showed that the Area IV Burn Pit did become radiologically contaminated. It was cleaned up during the 1990s and released for unrestricted use (i.e. declared clean) in 1998 by the California Department of Health Services (now Department of Public Health).

Dr. Morgenstern's report states: “There is little or no association, for total cancers and radiosensitive cancers among adults.” For the few cancers for which higher rates were reported, the report concludes that "There is no direct evidence from this investigation, however, that these observed associations reflect the effects of environmental exposures originating at SSFL."

And in his April 2014 study of area cancer rates, Dr. Thomas Mack of USC Keck School of Medicine concluded: "no evidence of measurable offsite cancer causation occurring as a result of emissions from Santa Susana."

Settlements of this nature are common and occur for a number of reasons unrelated to the merits of the claims being asserted. It is important to note that the overriding conclusion of numerous health studies is that people living near Santa Susana are not at increased risk for developing cancers as a result of past operations.

As a result of past rocket engine testing and energy research, chemicals seeped into the soil and groundwater at the Santa Susana Field Laboratory. The primary groundwater contaminant is trichloroethylene (TCE), a common industrial solvent. TCE was used in the early years at the lab to clean out residual fuel after rocket engine testing and degrease parts and equipment.

In 1984, Rocketdyne, the previous owner of �Ӱ���Ƶ’s property, began an extensive investigation and cleanup program to identify and prevent the spread of groundwater that was contaminated by past industrial activity. Groundwater investigation efforts at Santa Susana also have been conducted over several decades by the US Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA). This work has been performed under the oversight of the California Department of Toxic Substances Control (DTSC).

Groundwater investigations have revealed that groundwater plumes are stable and are not impacting human health or the environment.�� Data shows:

• site-related contaminants are stable and found within the boundaries of the site, with one minor exception in an area to the northeast,
• contaminated areas in the groundwater have decreased through the years and continue to shrink in size,
• testing of property surrounding the Santa Susana site revealed no traces of site-related chemicals in groundwater emerging above-ground through seeps and springs
• no community or private drinking water supply wells have been impacted by site-related chemicals.

This is mainly because the groundwater is found in the Chatsworth formation, which is primarily sandstone. Sandstone is formed of fine-grained rocks that can hold water like a sponge and with very small pores, sandstone serves as a good filter of surface pollutants. There is significant faulting and folding of the rocks below the site. These folds and cracks allow water to move through the rock, however, much of the water is stored in the pore spaces of the sandstone. As a result of the porosity of the sandstone, contaminants are diffused and absorbed into the bedrock and limit the movement of chemicals in groundwater. Most contaminants in groundwater at the site remain within about a half a mile of where they entered the groundwater about 60 years ago.

The Groundwater Advisory Panel was formed in 1996. It is made up of renowned experts in the fields of geology, site analysis and remediation, and the movement of chemicals in groundwater. The purpose of the Panel is to provide guidance to �Ӱ���Ƶ on how best to monitor and clean the groundwater under the site. Under the direction of the Panel, several new techniques have been developed and employed at the site to provide a detailed examination of the fractured bedrock and deep groundwater to study the distribution of the chemical contamination.

No. The groundwater below Santa Susana is not used for drinking water purposes onsite.�� The groundwater at Santa Susana also is not a source for municipal drinking water served to local communities.

Groundwater has been extensively tested at and around the Santa Susana site for decades.�� After many years of investigation, we have confirmed that no off-site water supply well is affected by contamination associated with past site activities at SSFL.�� The groundwater at the Santa Susana site is not migrating, and impacted areas are steadily decreasing in size.�� With one minor exception northeast of the �Ӱ���Ƶ property boundary, all of the groundwater impacts from past operations at SSFL are contained within the site boundary.

In addition, the groundwater at Santa Susana is part of a different aquifer with no connection to the aquifer that Simi Valley had proposed to use to supplement drinking water. In August 2018, the City of Simi Valley presented the Feasibility Study to Develop the Simi Valley Basin as a Potable Water Resource to the community.�� In response to community concerns about groundwater contaminants in Simi Valley, the study concluded that the Simi Valley Basin is independent of the Santa Susana Field Laboratory and its contaminants.

Research into the nature and extent of groundwater contamination started in 1987 and involves analyzing groundwater from more than 600 wells, investigating the nature of the groundwater system through a series of aquifer tests, mapping of the geology of Simi Hills, and identifying and sampling of seeps and springs. Several new investigation techniques have been developed and used for the first time at the site to provide a detailed investigation into the fractured bedrock and groundwater at Santa Susana.

In-situ Chemical Oxidation (ISCO)
�Ӱ���Ƶ conducted a pilot test to determine if injecting potassium permanganate solution into groundwater could remove volatile organic compounds (VOCs) in the saturated bedrock underneath the site. The technique has been used at other contaminated sites to oxidize chlorinated solvents into more benign substances. But Santa Susana is a more challenging environment because groundwater is constrained by fractures and faults and sandstone bedrock, unlike other sites with sand and gravel aquifers where groundwater is easier to treat.

Groundwater Interim Measures (GWIM)
The GWIM consists of a series of 13 extraction wells located across the site primarily in source areas or where containment concentrations are highest.�� The extracted groundwater is treated at �Ӱ���Ƶ’s Groundwater Extraction Treatment System (GETs) and is subjected to several state-of-the-art treatments, including ion exchange, air stripping, carbon absorption and ultra violet oxidation. �Ӱ���Ƶ’s contractors test the treated water to confirm that it meets levels stricter than drinking water standards.�� The clean water is then reinjected into the aquifer below the site.�� It is called an “interim measure” because it’s not a final approved cleanup remedy.

Bedrock Vapor Extraction (BVE)
�Ӱ���Ƶ is conducting a bedrock vapor extraction pilot test in the southeast area of the site to determine if vapor extraction can remove TCE in bedrock.�� It works by applying vacuum flow through the soil and fractured bedrock to extract vapors. Onsite, the vacuum is applied to extraction wells open to fractures and unsaturated porous bedrock and focuses in an area where high levels of TCE were found in partially saturated rock and groundwater.

Yes. Perchlorate was used in solid rocket motor research in two locations onsite at the field lab; approximately 95% of the rocket engine testing performed at Santa Susana was on liquid-fueled rocket engines without perchlorate.

Perchlorate was discovered in soil and groundwater at the Santa Susana Field Laboratory, consistent with the controlled areas where small rockets were previously tested and a former hazardous waste disposal site. Perchlorate related to activities at Santa Susana was not detected in any of the groundwater, surface water, sediment or soil samples collected at the Simi Valley site.

A perchlorate remediation was performed between 2004 and 2007 at the field lab. Approximately 15,500 cubic yards of soil was excavated and treated onsite, using a treatment approach approved by California Department of Toxic Substances Control (DTSC) and the Los Angeles Regional Water Quality Control Board (Regional Board). �Ӱ���Ƶ is also pumping and treating groundwater from several areas onsite where groundwater was impacted by historical site operations, including where perchlorate is detected.

No. There is no evidence that the perchlorate detected in Simi Valley wells is related to past operations at Santa Susana. This conclusion is based on a comprehensive��completed by the Army Corps of Engineers in 2007 and numerous other investigation reports and studies.

In the early 2000s, perchlorate was detected in surface soil at the site of the proposed Dayton Canyon development located in West Hills. Although perchlorate was not detected again in that location, an investigation was conducted in connection with DTSC and the Regional Board regarding the potential for perchlorate to move from Santa Susana to the Dayton Canyon development site. Hundreds of soil, sediment, groundwater and surface water samples were collected adjacent to the known use areas at Santa Susana, including drainage areas leading from Santa Susana to the Dayton Canyon site. No evidence of perchlorate was found in any of the offsite sample locations and DTSC released the area for residential development in 2008.

�Ӱ���Ƶ’s National Pollutant Discharge Elimination System (NPDES) permit allows �Ӱ���Ƶ to reroute surface water (particularly outfalls 005, 006 and 007) into unlined ponds that result in seepage into the groundwater, which is used by a large part of the Simi Valley community for drinking water.

It is important to note that �Ӱ���Ƶ, DOE and NASA are working under the oversight of Department of Toxic Substances Control to reduce contamination in groundwater at Santa Susana. Groundwater below the site is not — and never will be — used for public consumption. Last year, DTSC issued a Land Use Covenant and Agreement that restricts the use of groundwater at the site for domestic use or human consumption.�� In addition, the use of groundwater for drinking water purposes is expressly prohibited in the 2017 Conservation Easement that �Ӱ���Ƶ recorded over our approximately 2,400 acres at Santa Susana.

The ponds are dry most of the year. They fill up during rain events, then we run the water through the treatment system and discharge the treated water so we have capacity for the next rain event.�� This practice does not leave much opportunity (time) for infiltration.�� Silvernale pond, in particular, does not allow much infiltration because there is a shallow shale layer that prevents infiltration into the deeper aquifer.

The Groundwater Expert Panel has studied the groundwater contamination at SSFL for decades, and based on their analysis of hundreds of monitoring wells both on and off site, with the exception of a small TCE plume just outside �Ӱ���Ƶ property boundary in the NE corner of the site, there is no evidence that the site contaminants have impacted offsite groundwater.

In 2018, the Regional Board hosted a hearing on the City of Simi Valley’s groundwater feasibility study.�� During that hearing, water purveyors and groundwater experts testified that the groundwater at Santa Susana is part of a different aquifer with no direct connection to the aquifer that Simi Valley had proposed to use to supplement drinking water supplies. In addition, they testified that contamination that may exist in the Simi Valley aquifer is from local sources and not related to Santa Susana operations.

�Ӱ���Ƶ conducted a detailed evaluation of historical document databases prepared for the �Ӱ���Ƶ Resource Conservation and Recovery Act Facility Investigation (RFI) subareas to identify any reference to use of PFAS and “Suspect Materials.” These records indicated:

• Only small quantity usage or storage of PFAS/Suspect Materials. Large quantity use or storage of PFAS is not documented at any of the �Ӱ���Ƶ RFI sites.
• Documented PFAS/Suspect Materials were related to oils, lubricants, and greases. Heavy end petroleum hydrocarbon fraction sampling results were evaluated in areas with potential oil-, lubricant-, or grease-related PFAS/Suspect Materials use or storage. Soil and groundwater hydrocarbon concentrations in these areas are generally low and do not indicate significant oil or grease releases to the environment.
• Some of the records relate to Teflon or Viton. According to the Interstate Technology and Regulatory Council (ITRC), an environmental coalition working to create innovative solutions and best management practices, Teflon is “a ‘polymer of low concern’ due to high molecular weight and extreme stability.” Viton is resistant to “all aliphatic, aromatic and halogenated hydrocarbons, acids, animal and vegetable oils” (DuPont, 2020) and has “exceptionally good resistance to atmospheric oxidation” (CP Lab Safety, 2020). Therefore, mobility for these substances in the environment is expected to be negligible and they are unlikely to impact groundwater.

In 2021, the Regional Board and DTSC asked �Ӱ���Ƶ (and NASA and DOE) to sample groundwater in several areas onsite for PFAS compounds. In the 3rd quarter 2023, �Ӱ���Ƶ collected groundwater samples in three areas of known fire suppression demonstrations. These areas include: 1) Building 1319 where the fire engine and a canister with Aqueous Film-Forming Foam��(AFFF) were located, 2) the Lower Lot where firefighting demonstrations were historically conducted, and 3) Former Fire Department Demonstration Area 4 in AIBP where firefighting demonstrations were historically conducted.

�Ӱ���Ƶ’s sampling is still under laboratory testing and review. A report of the results is expected to be submitted to DTSC in the third quarter of 2024.

Groundwater is already being cleaned up at several locations of the site under DTSC direction (Groundwater Interim Measure). The groundwater interim measure will continue and may be a portion of the final groundwater cleanup.

The Settlement Agreement provides a streamlined process under RCRA FIRST program for further remediation of groundwater. According to the schedule included in the Settlement Agreement, implementation of the final groundwater remedy will begin in mid-2025. (Exhibit 17 of the Settlement Agreement provides additional detail on the groundwater cleanup process.)

No. In response to concerns expressed by community members, �Ӱ���Ƶ prepared a Human Health Risk Assessment (HHRA), an environmental risk assessment, under the direction of the Regional Board.

The HHRA evaluated potential exposure of individuals who may come into contact with stormwater from the Santa Susana Field Lab in drainage areas immediately downstream of the property boundary while hiking, rafting or other recreational uses.�� The report considered possible ways recreational users could have direct exposure to the surface water, such as incidental ingestion, skin contact and inhalation.�� The HHRA, which was reviewed and approved by the California Office of Environmental Health Hazard Assessment (OEHHA), concluded that:

Potential recreational exposures to Constituents of Potential Concern (COPCs) in surface water runoff exiting the Santa Susana site via Outfalls 001, 002, 008, 009, 011, 018, and 019 are below levels of concern as established by Cal-EPA and USEPA. This includes those COPCs that have had NPDES permit limit exceedances, such as lead and dioxins.

The final HHRA is located .

No. People who live in the vicinity of the site are safe. Based on thousands of soil samples collected onsite and offsite, individuals who live near the site are not exposed to any ground contamination. The exceedances that have occurred over time in stormwater are generally caused by metals and inorganics in soil at naturally occurring levels.

Portions of our stormwater management and treatment systems were damaged in the Simi Valley fire, however, once it was safe for �Ӱ���Ƶ’s Santa Susana team to return to the site after the fire, the piping and most of the other components were fully restored to pre-fire capabilities. The majority of the repair work was completed by January 2019.

• After the Woolsey fire, �Ӱ���Ƶ collected surface water samples in response to 10 qualifying rain events and submitted the data to the Regional Board as part of the regular quarterly reports in accordance with the NPDES permit.
• While several exceedances were identified, additional laboratory analysis showed that only naturally occurring radionuclides were detected, and the Stormwater Expert Panel indicated that the other exceedances were likely the result of the wildfire and not from erosion of contaminated soil.�� The Expert Panel is still evaluating the data and will include findings on the cause of the exceedances in their 2019 Annual Report, which will be available here.������

The California Water Code states that penalties do not apply when permit violations are caused by unanticipated, grave natural disasters like the Woolsey Fire. The Regional Board has determined that the exceedances detected at Santa Susana were due to the Woolsey Fire. The only penalties assessed against �Ӱ���Ƶ were for dioxin because they are excluded from the natural disaster exemption.

The Stormwater Expert Panel wrote a memorandum explaining why surface water doesn’t continually flow from the site into the Bell Canyon neighborhood. Flow in Bell Canyon in the dry season is from groundwater emerging in springs and through runoff from neighborhood activity. The spring water has been tested and there are no site-related ground contaminants present in the Bell Canyon drainage downstream of the Santa Susana Field Lab property boundary. There also has been extensive soil testing in drainages in Bell Canyon and there are no site-related ground contaminants in the drainages south of the Santa Susana property boundary.

Surface water drainages from the Santa Susana site do not flow into Black Canyon or enter the Knolls neighborhood because of the area’s topography. In addition, water that flows from seeps to Black Canyon has been tested and there are no site-related contaminants present.