HomeMy WebLinkAboutCC RES 26-36Docusign Envelope ID: 8F2E232B-56DB-8756-83FC-A03C6CC4D1C6
RESOLUTION 26-36
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF TUSTIN,
CALIFORNIA PROCLAIMING THE LOCAL EMERGENCY RELATED TO THE
NAVY NORTH HANGAR FIRE TO BE TERMINATED
WHEREAS, Tustin Municipal Code sections 5204 and 5205 empower the City
Manager, as the Director of Emergency Services, to declare the existence or threatened
existence of a local emergency; and
WHEREAS, California Government Code section 8550 et seq., including section
8558(c), authorizes the City Manager to proclaim a local emergency when the City is
threatened by conditions of disaster or extreme peril to the safety of persons and property
within the City that are likely to be beyond the control of the services, personnel,
equipment, and facilities of the City; and
WHEREAS, the California Government Code section 8630(c) requires Local
Proclamation of Emergency to be reviewed at least once every 60 days by the governing
body until terminated; and
WHEREAS, California Government Code section 8630(d) requires the governing
body to proclaim the termination of the local emergency at the earliest possible date that
conditions warrant; and
WHEREAS, on Tuesday, November 7, 2023, a fire erupted on the
decommissioned Marine Corps Air Station, Tustin at the North Hangar, a wooden
structure, constructed in the 1940's and designated as a Historical Landmark; and
WHEREAS, the U.S. Navy is the responsible owner of the parcel that includes the
North Hangar, but does not maintain firefighting or other equipment due to the
decommissioned status of former Marine Corps Air Station Tustin; and
WHEREAS, conditions of extreme peril to the safety of persons and property arose
in City of Tustin due to the fire and the release of chemicals of public health concern
including asbestos; and
WHEREAS, the Acting City Manager issued a Proclamation of Local Emergency
on November 9, 2024; and
WHEREAS, the City Council ratified the Proclamation of Emergency at an
emergency meeting convened on November 10, 2023; and
WHEREAS, the City Council met on January 9, 2024, to review the local
emergency and determined that the need for the local emergency continued to exist; and
Resolution 26-36
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WHEREAS, the City Council subsequently met during its regular meetings on
March 5, 2024, April 16, 2024, June 4, 2024, June 18, 2024, July 16, 2024, August 20,
2024, October 15, 2024, December 3, 2024, January 21, 2025, March 18, 2025, May 6,
2025, June 17, 2025, August 5, 2025, September 16, 2025, November 4, 2025,
December 16, 2025, February 3, 2026, March 17, 2026, and May 5, 2026 to again review
the need to continue the local emergency and, by adoption of Resolutions 24-20, 24-25,
24-39, 24-46, 24-50, 24-58, 24-74, 24-86, 25-06, 25-19, 25-36, 25-52, 25-57, 25-61, 25-
70, 25-75, 26-06, 26-12, and 26-20, respectively, determined that the need for the local
emergency continued to exist on each of those dates; and
WHEREAS, an Environmental Health Unit (EHU) comprised of Federal, State and
local regulatory, health, and environmental agencies, the City and the Navy oversaw the
emergency cleanup response actions; and
WHEREAS, the City and the Navy entered into a Cooperative Agreement wherein
the City would act as the Navy's Response Action Contractor and retain contractors,
funded by the Navy, to assist with the emergency; and
WHEREAS, the City and its contractors developed a system for residents to
identify and request cleanup of debris found in the community, which was approved by
the EHU. This phase of the response effort began shortly after the fire commenced and
continued until November 2024; and
WHEREAS, during the course of the "on the ground" cleanup effort, the City and
its contractors determined that debris deposited in gutters and on roofs would continue
to fall to the ground after wind or rain events, requiring additional rounds of "on the ground"
cleanup. This led the EHU to recommend an "above -ground" cleanup effort where a final
mobilization would occur to clean gutters and roofs in an EHU-approved work area. The
City developed an "above -ground" workplan, which was approved by the Navy and EHU;
and
WHEREAS, the City began the "above -ground" phase of work in December 2024
and the above -ground work approved in that plan was completed, subject to review
determination by the EHU members with jurisdiction that all work performed in response
to the Navy North Hangar Fire is complete; and
WHEREAS, the Navy led the effort to contain, remove and dispose of the
remaining asbestos -containing debris within and around the former North Hangar. The
City was not involved and did not have any input on the implementation of the Navy's
contracts for the Navy's work; and
WHEREAS, the City and the Navy each summarized their many months of
response activities related to the Navy North Hangar and submitted comprehensive after -
action reports to the EHU about the response actions; and
Resolution 26-36
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WHEREAS, on June 3, 2026, the City submitted its final Navy North Hangar Post -
Fire Action Summary Report to the EHU and DTSC; and
WHEREAS, based on their review of the City's After -Action Report, all EHU
agencies concurred with the City's findings that the cleanup actions performed are
sufficient to protect human health and the environment, and on June 9, 2026, the
California Department of Toxic Substances Control ("DTSC") acknowledged in writing the
successful completion of the City's response efforts as follows:
"After review, DTSC confirms that the Report adequately documents the
emergency response, monitoring, and remedial actions taken places as part of
the Navy North Hangar post -fire action. This message serves as a formal
acknowledgement that City of Tustin's remediation of the Navy North Hangar is
now complete.
"DTSC also recognizes that the completed work contributes positively to the
protection and well-being of the surrounding communities, including those most
impacted. DTSC appreciates the effort and coordination with all agencies
involved in achieving this outcome."
THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF
TUSTIN AS FOLLOWS:
Section 1. The City of Tustin's proclaimed local emergency related to the Navy
North Hangar Fire is hereby terminated, effective immediately.
PASSED AND ADOPTED at a regular meeting of the City Council of the City of
Tustin held on the 16t" day of June 2026.
AUSTIN LUMBARD,
Mayor
ATTEST:
tvica N. if
ERICA N. YASUDA,
City Clerk
Resolution 26-36
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I_1„MAMA21Il_1MI W12MVMI
DAVID E. KENDIG,
City Attorney
STATE OF CALIFORNIA )
COUNTY OF ORANGE ) SS
CITY OF TUSTIN )
I, Erica N. Yasuda, City Clerk and ex-officio Clerk of the City Council of the City of Tustin,
California, do hereby certify that the whole number of the members of the City Council of
the City of Tustin is five; that the above and foregoing Resolution No. 26-36 was duly passed
and adopted at a regular meeting of the Tustin City Council, held on the 16th day of June,
2026, by the following vote:
COUNCILMEMBER AYES:
COUNCILMEMBER NOES:
COUNCILMEMBER ABSTAINED:
COUNCILMEMBER ABSENT:
Lumbard. Schnell. Fink. Nielsen
0
(0)
(0)
Gallaaher (1)
COUNCILMEMBER RECUSED: (0)
` iyica. N. ASL4a,
ERICA N. YASUDA,
City Clerk
Resolution 26-36
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Prepared for:
City of Tustin
Acting as the U.S. Navy's Response Action Contractor
300 Centennial Way
Tustin, California 92780
Navy North Hangar Post -Fire Action Summary Report
Former Marine Corps Air Station
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Hitchens
No.7593
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Tustin, California
Prepared by:
Brian Hitchens, P.G., C.H.G.
Senior Principal Hydrogeologist
Geosyntec"'
consultants
engineers I scientists I innovators
13400 Sabre Springs Pkwy, Suite 135
San Diego, California 92128
June 3, 2026
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EXECUTIVE SUMMARY
A fire began at the United States Navy (Navy) -owned North Hangar located at the former
Marine Corps Air Station (MCAS) in Tustin, California (Navy North Hangar, or Site,
Figure 1) on November 7, 2023 (Hangar Fire). Response teams from the Orange County
Fire Authority (OCFA) mobilized to extinguish the fire but were unable to control the
fire due to the extraordinary size of the 17-story wooden blimp hangar structure. Because
of safety concerns for the firefighters, the OCFA made the decision to allow the Hangar
Fire to burn itself out while applying fire suppression to limit its spread (New Santa Ana,
2023). On November 9, 2023, the County of Orange (County) and the City of Tustin
(City) separately declared a public emergency. Schools, parks, adjoining roads, and
commercial businesses were closed. Fire -related ash and debris were broadly deposited
in the surrounding neighborhoods and commercial areas as a result of the fire.
To coordinate the emergency response and evaluate potential impacts of the ash and
debris, the OCFA established 12 "Divisions" of potentially impacted areas for
management purposes, as depicted in Figure 2. OCFA declared the fire extinguished
after 24 days, on December 1, 2023 (CTEH, 2024).
This Navy North Hangar Post -Fire Action Summary Report (Report) summarizes the
residential and commercial area, post -fire response emergency actions implemented by
the City (i.e., off -site of the federally owned property). The City served as the Navy's
designated "Response Action Contractor" at the closed military installation pursuant to
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
Section 119, 42 U.S.C. § 9619, to address potential environmental impacts from the
Hangar Fire to the surrounding communities.
To support the emergency residential response and debris removal work, federal, state,
and county environmental and public health regulators immediately reported to the
"Emergency Operation Center (EOC)" at Tustin City Hall. These agencies formed an
"Incident Management Team (IMT)" with the Navy and City on November 8, 2023,
which would later be known as the "Environmental/Health Unit" (EHU), a multi -agency
body which brought together expert regulatory, public health, and technical input for the
management and oversight of the environmental assessment and public health response
to the Hangar Fire. Members of the EHU include the United States Environmental
Protection Agency (USEPA), California Department of Toxic Substances Control
(DTSC), South Coast Air Quality Management District (South Coast AQMD), Orange
County Health Care Agency (HCA), Navy, City, and their respective environmental
consultants, and emergency response subcontractors.
Regional air quality monitoring and the testing of Hangar Fire debris commenced on
November 7, 2023, and continued through June 23, 2025 (approximately 19 months).
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Active remediation work by the City and its subcontractors outside the Navy North
Hangar footprint itself required approximately 18 months (November 2023 — May 2025)
to complete and, excluding the Navy's cleanup activities, cost approximately $105.8
million.
On November 10, 2023, the City entered into a Cooperative Agreement with the Navy
for the "City to take all appropriate emergency measures necessary to protect any
imminent and substantial endangerment to human health or environment related to" the
Hangar Fire, and the Cooperative Agreement provided interim Navy funding to respond
to the Hangar Fire. On December 8, 2023, the Navy formally designated the City to be
its "Response Action Contractor" in the Second Amended Cooperative Agreement. The
City -Navy Cooperative Agreement is novel because it is the first time in history that a
municipality has served in a Federal Response Action Contractor role. In that role, the
City used its emergency authority to hire teams of subcontractors equipped and trained to
clean up the hazardous materials released during the Hangar Fire. The City led an
unprecedented nearly 24-month emergency environmental management response to
monitor and protect the public health of the surrounding community.
This Report provides a comprehensive summary of the environmental monitoring and
remedial actions undertaken by the City, acting as the Navy's Response Action
Contractor, during the nearly 24 months following the Hangar Fire event. In parallel with
the City's response actions in the residential and commercial areas around the destroyed
Navy North Hangar, the Navy performed all necessary emergency response actions to
remediate the destroyed Navy North Hangar structure.
On November 28, 2023, USEPA Region 9 issued a Notice of Federal Response Action
to the Navy (USEPA, 2023c). Specific required actions included:
• Preparation of a Workplan describing waste removal strategy and disposal
facilities;
• Preparation of a Health and Safety Plan;
• Preparation of a Sampling and Analytical Plan;
• Proof of compliance with Hazardous Waste Operations and Emergency Response
requirements for all subcontractors;
• Maintenance of Site security;
• Prevention of off -site discharges of hazardous substances;
• Characterization, collection, and removal of all hazardous substances;
• Production of manifests for all waste removed to an appropriate disposal facility;
and
• Maintenance of an IMT to coordinate actions with appropriate state and local
regulatory agencies and stakeholders.
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Response actions in residential, commercial, school, park, and public areas primarily
occurred over an 18-month period from November 7, 2023, through April 23, 2025, and
those activities involved the unprecedented and rapid mobilization of over 600 hazardous
material emergency response workers to inspect, monitor, and remove presumed
asbestos -containing material (PACM) from the neighborhoods and public areas
surrounding the Navy North Hangar.
Gathered Asbestos Removal Ground Response Team (December 2023).
Response actions necessary to (i) stabilize the Navy North Hangar Site, (ii) mitigate off -
site migration of Hangar Fire -related debris and contaminants, and (iii) demolish the
remaining remnants of the Navy North Hangar itself are addressed in the NAVFAC
Southwest Hangar 1 Emergency Response Completion Report (NAVFAC, 2026). The
Navy's report will cover the response actions, remediation, monitoring, sampling effort,
and cleanup of the Navy North Hangar.
On May 20, 2025, 19 months after the Hangar Fire commenced, USEPA Region 9 issued
a concurrence that (i) the Navy and its contractors had met the requirements of the Federal
Response Action and (ii) the USEPA Emergency Planning and Preparedness Branch had
no further concerns regarding the emergency actions at the Site and surrounding
residential areas (USEPA, 2025; Appendix N). On June 24, 2025, the Navy concluded
debris removal and active remediation of the demolished North Navy Hangar.
Air Monitoring
Within hours of the fire, environmental regulators identified asbestos and lead as the two
primary constituents of potential concern based on their known presence in certain Navy
North Hangar building materials. Because both lead and asbestos are naturally occurring
in California, the EHU performed extensive and continuous air monitoring and testing
around the Navy North Hangar and in residential areas. That continuous testing occurred
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during the Hangar Fire event itself and for the next 18 months of active residential area
cleanup. The air testing provided real-time data to determine whether there were
discernable increases in lead and airborne asbestos fibers above background conditions,
or if levels exceeded residential health screening levels in air, soil, and dust samples.
Air monitoring began on November 7, 2023, when the Hangar Fire first commenced, and
it then expanded and continued throughout the Navy North Hangar stabilization phase
and the subsequent removal of Hangar Fire -related debris from the community. The City,
Navy, USEPA, and South Coast AQMD contributed to the collection and evaluation of
air monitoring data.
South Coast AQMD commenced air monitoring in the early hours of the fire on
November 8, 2023, initially at four stations around the Navy North Hangar. From
November 15, 2023, through April 30, 2025, the City performed (and the EHU oversaw)
daily air quality monitoring over a wider area around the Navy North Hangar perimeter
and at approximately 23 stations established throughout the surrounding residential
communities to provide real-time information on particulate matter (PM) measuring less
than 10 microns in diameter (PM 10) in the air (Table 2). All data met the National Air
Quality Standard for PM 10, and the average monthly and overall PM 10 concentrations
throughout the 19-month monitoring period was consistently within the "good" air quality
range as defined by South Coast AQMD.
During the Hangar Fire event, and for the next 19-months, air samples were collected and
analyzed for the presence of respirable asbestos fibers at fence -line monitoring stations
around the Navy North Hangar perimeter and at approximately 20 stations established
throughout the surrounding residential communities (Tables 3 through 5). Over 4,800
asbestos -related air samples were collected between November 8, 2023, and June 23,
2025. From those thousands of samples, single asbestos fibers were detected in four air
samples obtained on October 26, 2024, November 4, 2024, January 20, 2025, and June 8,
2025, respectively, at one of the 23 monitoring stations. Each single -fiber detection
equates to a concentration of 20 structures per millimeter squared (s/mm2), which is below
the 70 s/mm2 USEPA Asbestos Hazard Emergency Response Act (AHERA) standard for
post -abatement clearance in schools (40 Code of Federal Regulations [CFR] Part 763
Appx. A, subpart E). Additionally, six unidentified fibers were detected in one sample
on December 19, 2023, using phase contrast microscopy (PCM). The PCM method will
identify the general presence of fibers but cannot determine whether the fibers are
asbestos or another fibrous material; therefore, this detection was not confirmed to be
asbestos. However, 26 other samples were collected on the same day (December 19,
2023), across 16 other surrounding stations, and no fibers of any type were identified in
any of these contemporaneous samples. Asbestos fibers are known to exist in the ambient
air in Southern California. The identification of single asbestos fibers in less than 0.1%
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of air samples collected over a nearly two-year period, all at concentrations below risk
screening levels, is consistent with natural background conditions.
In over 3,200 samples collected to evaluate lead in air, there were 15 positive detections,
13 of which were detected during the active fire between November 14 and November
20, 2023 (Table 1). Eight of these 15 lead detections were from the air testing stations
located adjacent to the Navy North Hangar, not within residential areas (EHU, 2023).
The National Ambient Air Quality Standard (NAAQS) for lead is a 3-month rolling
average concentration of less than 0.15 micrograms per cubic meter (ug/m3). Lead was
detected above 0.15 ug/m3 in only localized areas on five days over the 17-month
monitoring period:
• November 14, 2023: 1 of 7 samples
• November 15, 2023: 5 of 17 samples
• November 16, 2023: 1 of 37 samples
• November 17, 2023: 1 of 50 samples
• December 15, 2023: 1 of 20 samples
Public Area Soil and Dust Assessments and Clearances
From November 9 through December 27, 2023, HCA and/or USEPA collected 77 soil
and dust samples and tested them for lead at 29 Tustin Unified School District (TUSD)
locations, 12 City park locations, and numerous public areas surrounding or in proximity
to the Navy North Hangar. Concentrations of lead in all soil samples were below DTSC's
residential screening level of 80 mg/kg (DTSC, 2022) or within typical background
concentrations. Lead concentrations in all dust samples were also found to be below the
residential screening criteria of 100 ug/ft2 for dust on surfaces (HCA, 2024).
Presumed Asbestos -Containing Material Identification and Removal
As the Navy's Response Action Contractor, the City coordinated ongoing inspections and
the removal of PACM associated with the Hangar Fire from over 2,000 residential
locations, 29 schools, 12 public parks, public roads and spaces, and over 400 roofs,
gutters, and above -ground porches in the City beginning on November 16, 2023, through
April 23, 2025. The progressive sampling and clearance of the parks and schools by HCA
were communicated to the public through daily incident update reports (Appendix A).
Within days of the start of the Hangar Fire, the City mobilized over 600 trained hazardous
material emergency response workers from across the country, supervised by a team of
Certified Asbestos Consultants (CACs).
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Individual homeowners, area residents, and commercial property owners provided reports
of observed debris found on private and public properties online or through a City call
center. Locations reported to be impacted by any Hangar Fire debris were individually
remediated by teams of remediation workers, sometimes multiple times, until each
property or location was inspected and cleared by CACs. The work occurred for months
over three phases of ground -level inspection and remediation and one phase of above-
ground inspection and remediation of PACM from above -ground roofs, gutters, and
porches. This extensive emergency response program resulted in the aggregate collection
and disposal of over 737 tons of PACM (Appendix G).
Ground Response Team Conducting a Debris Recovery Sweep (January 2024)
Response Crew Preparing for Debris Clearance Along Railway North of Columbus Square
(December 2023)
City remediation subcontractors inspected and cleared over 1,500 sites during the period
immediately following the Hangar Fire between November 22, 2023, and January 12,
2024. However, the City mobilized and maintained the inspection and debris -clearance
teams for an additional 16 months to address residual PACM identified in the community,
typically following rainstorms and Santa Ana wind events. The completion in April 2025
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of four months of additional late -stage above -ground inspections and PACM removal
efforts was calculated to mitigate the risk of remobilization of PACM following future
wind/rain events. Consequently, the EHU approved suspending site inspections and
ground -level activities concurrently with the satisfactory completion of Phase IV's
above -ground response action work.
Initial North Hangar Stabilization and Debris Management
The threat of winds and winter storms following the Hangar Fire made the toppling of the
severely damaged 120-foot-tall hangar doors and the potential off -site migration of debris
a significant risk. Primarily in the first few months, the City took steps to hire crews and
heavy equipment to lower and dismantle the severely fire -damaged nested sliding doors,
apply a specially designed tackifier to encapsulate the fire debris in place, and install a
protective plastic barrier around the entire Navy North Hangar footprint until the Navy's
contractors could be mobilized for longer -term on -site cleanup. The complete turnover
of City stabilization to the Navy and its subcontractors for operations at the Hangar Site
cleanup occurred in August 2024.
z�
Application of Tackifier to Encapsulate On -Site Burn Debris
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Installation of Plastic Sheeting to Contain Debris Within the Hangar Structure
Hangar Door Deconstruction
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Hangar Doors After Removal and Deconstruction
Residential Soil and Interior Dust and Air Sampling
Pursuant to a work plan approved by the EHU, the City retained Geosyntec to perform
an interior and exterior residential study between January 31 and March 10, 2024. The
study focused on whether lead or asbestos in impacted areas existed above state or federal
screening levels in residential soil, household dust, or interior household air; and, if so,
whether those exceedances were potentially associated with ash or soot from the Hangar
Fire (Geosyntec Consultants, 2024). Geosyntec randomly selected a total of 80
residences from a pool of volunteers who responded to a community -wide public notice
of the public health survey.
A total of 88 outdoor composite soil samples, 640 indoor dust wipe samples, and 160
indoor air samples were collected from the combined "Study Area" (impacted areas
within Tustin) and residential locations in the "Control Area" (Santa Ana, Irvine).
A statistical analysis of these samples showed no detections of lead or asbestos above
regional background levels or regulatory screening criteria. The study also found no
increased detections of either lead or asbestos in Tustin area homes versus the unaffected
Control Area in Santa Ana and Irvine.
Summary
The collaborative partnership of the City, Navy, and EHU members efficiently
established under emergency conditions an unprecedented residential, commercial, and
public area cleanup effort in terms of overall scale. This emergency program removed
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over 737 tons of Hangar Fire -related debris and debris -impacted materials over the course
of 18 months from 29 TUSD locations, 12 City park locations, and over 2,000 residential
locations, commercial areas, public streets, and open areas.
Acting as the Navy's Response Action Contractor, the City also took steps to hire crews
and heavy equipment to lower and dismantle the severely fire -damaged nested sliding
doors, apply a specially designed tackifier to encapsulate the Hangar Fire debris in place,
and install a protective plastic barrier around the entire Navy North Hangar footprint until
the Navy's contractors could be mobilized for longer -term on -site cleanup. The complete
turnover of City stabilization operations at the Site itself to the Navy and its
subcontractors for cleanup occurred in August 2024.
The EHU established an extensive 24/7 air -monitoring network composed of Navy North
Hangar perimeter stations, and an additional 25 stations located in the surrounding
community to perform a continuous, long-term assessment of air quality during the
Hangar Fire event and for the next 18-months (November 2023-April 2025). Over 600
trained hazardous material emergency response workers canvassed entire neighborhoods
to identify and remove Hangar Fire -related PACM debris.
Working in conjunction with the EHU (USEPA, DTSC, South Coast AQMD, HCA, and
the Navy), the City completed all necessary and reasonable actions to contain and address
potential Hangar Fire -related impacts to the off -site residential/commercial communities.
The comprehensive sampling conducted during and after the Hangar Fire documents that
the extraordinary efforts undertaken by the City and the Navy were effective in mitigating
potential public health impacts related to the Hangar Fire event. The Navy has fully
stabilized the Site and removed Hangar Fire -related debris from the surrounding area
through exhaustive inspection and removal efforts.
On May 20, 2025, USEPA Region 9 issued written concurrence to the Navy and its
contractors that the requirements of the Federal Response Action have been met, and that
the USEPA Emergency Planning and Preparedness Branch had no further concerns
regarding the emergency actions taken related to the Navy Hangar Fire (USEPA, 2025).
Based on the data and the satisfactory completion of the 18-month multi -phased
remediation in the residential, commercial, school, park, and public and private areas
within the identified impact zones of the Hangar Fire, environmental conditions in those
areas are now sufficiently protective of human health and the environment in accordance
with the applicable regulatory standards established for the protection of public health
and the environment. Final demobilization of remediation teams and related efforts is
now appropriate. We conclude and recommend to the EHU that no further off -site actions
related to the Hangar Fire are necessary or required with respect to off -site areas,
including the off -site residential, commercial, park, or open space areas.
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TABLE OF CONTENTS
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Page
1. INTRODUCTION................................................................................................ 1
1.1
Background..................................................................................................1
1.2
Report Objective..........................................................................................
4
1.3
Report Organization....................................................................................
4
2. PROJECT TIMELINE..........................................................................................
5
3. CONSTITUENTS OF POTENTIAL CONCERN ...............................................
7
3.1
Asbestos.......................................................................................................7
3.2
Lead.............................................................................................................
7
3.3
Particulate Matter........................................................................................
7
4. RESPONSE ACTION SUMMARY.....................................................................
9
4.1
Air Monitoring.............................................................................................
9
4.1.1 Air Toxic Metals Monitoring (November 10, 2023 — May 14,
2024)..............................................................................................
10
4.1.2 Air Particulate Monitoring (November 16, 2023 - April 30,
2025)..............................................................................................
11
4.1.3 Asbestos Air Monitoring (November 7, 2023 - June 23, 2025) ....
12
4.1.4 Ambient Air Monitoring (November 2023)..................................
13
4.2
School, Park, and Public Areas Assessments and Clearances
(November — December 2023)..................................................................
13
4.3
The Four Phases of the Navy North Hangar Fire Emergency
Remediation...............................................................................................
14
4.4
Ground Remediation Overview (November 2023 — December 2024) ......
16
4.4.1 Phase I Ground -Level Remediation Response (November 7,
2023 - January 12, 2024)...............................................................
17
4.4.2 Phase II Ground -Level Remediation Response (January 8, 2024
- February 25, 2024)......................................................................
19
4.4.3 Phase III Ground -Level Remediation Response (February 25,
2024 - December 11, 2024)...........................................................
20
4.5
Phase IV Above -Ground Remediation Response Activities (December
11, 2024 - April 23, 2025).........................................................................
20
4.6
December 2023 HCA Webinar.................................................................
23
4.7
Residential Exterior and Interior Public Health Study (January 31,
2024 - March 10, 2024).............................................................................
26
5. CONCLUSIONS AND RECOMMENDATIONS .............................................
30
6. REFERENCES...................................................................................................
32
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TABLE OF CONTENTS (Continued)
LIST OF TABLES
Table 1 Summary of Air Toxic Metal Results: Lead
Table 2 Summary of Air Particulate Matter (PM10) Results
Table 3 Summary of Asbestos Air Monitoring Results: Navy North Hangar Perimeter
Table 4 Summary of Asbestos Air Monitoring Results: Surrounding Community
Table 5 Summary of Asbestos Air Monitoring Results: Long Term Monitoring
LIST OF FIGURES
Figure 1 Site Location
Figure 2 Orange County Fire Authority Fire/Emergency Response Divisions
Figure 3 Air Sampling Locations
Figure 4 Phase I Ground Remediation Emergency Response Locations
Figure 5 Phase II Ground Remediation Emergency Response Locations
Figure 6 Phase III Ground Remediation Emergency Response Locations
Figure 7 Phase IV Above -Ground Remediation Emergency Response Locations
LIST OF APPENDICES
Appendix A EHU Daily Incident Reports
Appendix B ATM results November 2023 — May 2024
Appendix C Air PM Results November 2023 — April 2025
Appendix D
Asbestos Air Monitoring Results November 2023 — June 2025
Appendix E
South Coast AQMD VOC Air Monitoring Results
Appendix F
HCA School, Park, and Public Areas Assessments and Clearances
Appendix G
Hazardous Waste Manifests
Appendix H
Phase I Ground Remediation Response Data
Appendix I
Phase II Ground Remediation Response Data
Appendix J
Phase III Ground Remediation Response Data
Appendix K
Phase IV Above -Ground Remediation Response Data
Appendix L
Photographic Record
Appendix M
Residential Study
Appendix N Regulatory Concurrence Letters
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LIST OF ACRONYMS AND ABBREVIATIONS
ug/m3
micrograms per cubic meter
ACM
Asbestos -containing materials
AHERA
Asbestos Hazard Emergency Response Act
AQI
air quality index
ATI
asbestos abatement subcontractor
ATMs
air toxic metals
BRAC
Base Realignment and Closure Act
CACs
Certified Asbestos Consultants
CARB
California Air Resources Board
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act
CFR
Code of Federal Regulations
City
City of Tustin
cm
square -centimeter
County
County of Orange.
CPSC
Consumer Product Safety Commission
DTSC
Department of Toxic Substances Control
EHU
Environmental/Health Unit
EOC
Emergency Operation Center
Hanger Fire
Navy North Hanger Fire
HEPA
High -Efficiency Particulate Air
IEM
Innovative Emergency Management
IMT
Incident Management Team
MCAS
Marine Corps Air Station
NAAQS
National Ambient Air Quality Standard
NAVFAC
Naval Facilities Engineering Systems Command
Navy
United States Navy
OC
Orange County
OCFA
Orange County Fire Authority
HCA
Orange County Health Care Agency
PACM
Presumed Asbestos -Containing Material
PCM
phase contrast microscopy
PM
particulate matter
PM10
particulate matter (<10 microns in diameter)
ppm
parts per million
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LIST OF ACRONYMS AND ABBREVIATIONS (Continued)
QA/QC
quality assurance/quality control
Report
Navy North Hangar Post -Fire Action Summary Report
s/mm2
structures per millimeter squared
South Coast AQMD
South Coast Air Quality Management District
Site
Navy North Hanger
TEM
transmission electron microscopy
TUSD
Tustin Unified School District
USEPA
United States Environmental Protection Agency
VOCS
volatile organic compounds
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1. INTRODUCTION
This Navy North Hangar Post -Fire Action Summary Report (Report) has been prepared
by Geosyntec Consultants, Inc. (Geosyntec) on behalf of the City of Tustin (City) to
summarize the off -site emergency response actions undertaken in residential,
commercial, municipal, park, and school areas between November 2023 and June 2025.
The City and the City's subcontractors performed these emergency response actions
following the Navy North Hangar Fire (Hangar Fire), located on a portion of the former
Marine Corps Air Station (MCAS) Tustin (the Site, Figure 1) that is owned by the United
States Navy (Navy).
The Navy and the City divided the work as follows: The City, operating as the Navy's
Response Action Contractor, oversaw all on -site and off -site response actions from the
start of the Hangar Fire response until July 8, 2024, after which the Navy took over
remediation of the hangar footprint at the Site, and the City and its subcontractors
continued remediation of residential and commercial areas, schools, and public roads and
spaces. The Navy and the City completed their respective response actions with the
oversight and support of federal, state, and local regulatory and public health agencies,
including: the United States Environmental Protection Agency (USEPA), California
Department of Toxic Substances Control (DTSC), South Coast Air Quality Management
District (South Coast AQMD), Orange County Health Care Agency (HCA), which
collectively constitute the Navy North Hangar Fire Environmental/Health Unit (EHU).
Response actions performed by the City outside of the hangar footprint included, among
other things, residential and commercial area sampling and remediation, air monitoring,
park inspections and remediation, and Tustin Unified School District (TUSD) school
inspections and remediation. This Report summarizes the event timeline, data collection,
evaluation of potential impacts, and response actions performed in the residential,
municipal, commercial, school, and park areas surrounding the Site. The Navy is
preparing the Naval Facilities Engineering Systems Command (NAVFAC) Southwest
Hangar 1 Emergency Response Completion Report detailing the monitoring,
containment, remediation, and demolition activities performed by the Navy and its
subcontractors at the Site (NAVFAC, 2026). Mr. Michael Flaugher, PG, and
Ms. Victoria Severin-Marshall, PG, prepared this Report with review by Mr. Brian
Hitchens, PG, CHG, all of Geosyntec, in accordance with the review policy of the firm.
1.1 Background
The Navy North Hangar (also designated as Hangar I/Building 28) was constructed in
1942 as part of a multi -hangar blimp base during World War II. The Navy North
Hangar's primary usage changed over time, and it operated as part of MCAS Tustin as a
helicopter hangar starting in 1951. The military operationally decommissioned MCAS
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Tustin and the Navy North Hangar on July 3, 1999, as part of recommendations made in
1991 and 1993 in connection with the Base Realignment and Closure Act (BRAC)
process.
The Navy North Hangar stood as one of the largest wooden structures ever built (RBF
Consulting, 2008). The Navy North Hangar was 17 stories tall, over 1,000 feet long and
300 feet wide. Asbestos -containing materials (ACM) and lead -based paint were present
in some components of the Navy North Hangar structure. On November 7, 2023, a fire
began in the early -morning hours at the Site. The Orange County Fire Authority (OCFA)
responded with ground -based and airborne response teams. Because of the extraordinary
size of the structure and safety concerns for the firefighters, the OCFA made the decision
to allow the fire to burn while applying fire suppression to limit its spread (New Santa
Ana, 2023). Because ACM was present and damaged by the fire, all fire -related debris
was treated as presumed asbestos -containing material (PACM). Sealant was also
regularly applied to remaining on -site fire debris in and immediately around the hangar
footprint to mitigate wind-borne migration.
No Navy personnel or assets were stationed at the closed MCAS Tustin installation to
respond to the fire emergency. Consequently, the Navy first entered into a Cooperative
Agreement with the City three days after the Hangar Fire commenced, and weeks later,
in the Second Amended Cooperative Agreement, the Navy formally designated the City
on December 8, 2023, to serve as its "Response Action Contractor" under federal law.
This was the first time in history that a municipality was called upon to serve the federal
government as a Response Action Contractor. The mobilization by the City was
immediate; it engaged municipal, state, and federal resources to protect public health in
response to the Hangar Fire on November 8, 2023, and declared an emergency on
November 9, 2023.
The City and the OCFA immediately established an emergency command center at Tustin
City Hall and started daily public briefings. A team from the initial group of federal,
state, and county regulators first organized on November 8, 2023, in the OCFA and City
command center to support the OCFA, known then as the "Incident Management Team
(IMT)" during the early days of the emergency. When the OCFA declared the Hangar
Fire extinguished weeks later, representatives from the City, Navy, USEPA, DTSC,
South Coast AQMD, and HCA formed the EHU for longer -term environmental and
public health protection and oversight of the response.
The Navy, USEPA, South Coast AQMD, and HCA immediately set up a network of air
monitoring stations around the Navy North Hangar and surrounding residential areas
between November 7 and November 8, 2023, and began continuous air monitoring
activities. On November 10, 2023, the City entered into a Cooperative Agreement to
support the Navy and hired hundreds of available hazardous materials emergency workers
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from across the country under emergency contracting procedures. The Cooperative
Agreement included provisions for the Navy to reimburse the City for its emergency
response costs.
Schools, roads, and businesses were closed until each was inspected by Certified
Asbestos Consultants (CACs), remediated by trained cleanup teams, and reinspected by
CACs. The EHU provided daily Incident Response Summaries to the public from
November 12, 2023, through December 20, 2023, to keep the community apprised of the
daily progress and environmental conditions during the early phases of the incident
response (Appendix A).
The City initially engaged the OCFA as the on -site emergency responder during the early
weeks of the Hangar Fire. The OCFA established 12 neighborhood or area "Divisions"
to coordinate the response and evaluate the potential impacts of the ash and debris, as
depicted in Figure 2. On November 22, 2023, the initial phase of ground -level
remediation began, which involved mobilizing asbestos -trained abatement workers from
around the country, with over 600 trained emergency responders contributing to the
ground -level cleanup, seven days a week at the height of operations. When the active fire
ended on December 1, 2023, the daily management of the long-term emergency response
actions moved from the OCFA to Innovative Emergency Management (IEM), a
professional emergency response subcontractor hired by the City.
On November 28, 2023, USEPA Region 9 issued a Notice of Federal Response Action
to the Navy (USEPA, 2023c). This notice documents USEPA's observation of a release
or threatened release of hazardous substances, pollutants, or contaminants from the Site
and identified the Navy as the party responsible for implementing a response action.
Specific required actions included:
• Preparation of a Workplan describing waste removal strategy and disposal
facilities;
• Preparation of a Health and Safety Plan;
• Preparation of a Sampling and Analytical Plan;
• Proof of compliance with Hazardous Waste Operations and Emergency Response
Requirements for all subcontractors;
• Maintenance of Site security;
• Prevention of off -site discharges of hazardous substances;
• Characterization, collection, and removal of all hazardous substances;
• Production of manifests for all waste removed to an appropriate disposal facility;
and
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• Maintenance of an IMT structure to coordinate actions with appropriate state and
local regulatory agencies and stakeholders.
Navy responded to USEPA by email on November 30, 2023, stating their intent to
continue and complete the response.
1.2 Report Objective
This Report provides a comprehensive summary of the emergency response, monitoring,
and remedial actions undertaken by the City, acting as the Navy's Response Action
Contractor and its subcontractors in the months following the Hangar Fire from
November 2023 through June 2025. These actions include real-time air quality
monitoring from November 2023 through June 2025 (19 months) and ground -level
surveys, debris removal, and home -by -home ground -level and above -ground cleanup
actions from November 2023 through May 2025 (18 months). The underlying data,
summaries, and conclusions from the numerous interim action reports and data
deliverables are directly incorporated into the appendices of this Report.
1.3 Report Organization
The remainder of this Report consists of the following:
• Section 2 — Project Timeline: Presents a chronological summary of response
actions from November 7, 2023, through June 23, 2025;
• Section 3 — Constituents of Potential Concern: Presents the primary constituents
of potential human health concern related to the Hangar Fire;
• Section 4 — Response Action Summary: Describes and summarizes each phase of
post -Hangar Fire response activities;
• Section S — Conclusions and Recommendations; and
• Section 6 — References: Citations for referenced documents and reports.
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2. PROJECT TIMELINE
The timeline presented below provides context for the various post -Hangar Fire response
actions performed on- and off -site.
D.TE(S)
RESPONSE ACTION CHRONOLOGY
11/07/23
Hangar Fire begins. South Coast AQMD air monitoring commences.
11/08/23
Environmental regulators report to the Emergency Operation Center (EOC)
and operate as the IMT, which later becomes the multi -agency EHU. More
extensive air monitoring and debris sampling begins.
11/10/23-11/22/23
Initial Air Toxic Metals (ATM) Survey. Multiple agencies conducted initial
ATM measurements.
11/09/23-12/27/23
HCA dust and soil lead testing. All results meet health screening criteria.
11/10/23
Navy and City enter a Federal Cooperative Agreement for off -Site
environmental response actions, later amended on December 8, 2023, to
designate the City as the Navy's Response Action Contractor under the
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) Section 119. The City and Navy amended the Cooperative Agreement
several times to increase available funding as the response grew.
11/12/23
Local park facilities closed.
11/13/23
All TUSD schools closed pending testing and clearance.
11/14/23-6/23/25
Air quality measurements. The EHU implements air quality monitoring for daily
sampling of ATMs, particulate matter less than 10 microns in diameter (PM10),
and airborne asbestos fibers.
11/22/23-01/12/24
Phase I initial ground -level remediation performed. Initial cleanup of PACM
at multiple location types (schools, residential, commercial, etc.) based on visual
inspections by CAC firms contracted by the City of impacted areas and survey
responses/requests from the community.
11/26/23
EHU developed Air Monitoring Strategy/Trajectory. Plan established
quantities and locations of monitors and constituents to monitor for (e.g., dust,
asbestos, and/or metals) throughout the various phases of the response.
11/28/23
USEPA issues Notice of Federal Response Action to Navy.
12/01/23
Hangar Fire is declared extinguished by the OCFA.
12/10/23
All 29 TUSD schools have been inspected, mitigated, and cleared for opening.
12/12/23
All parks have been inspected, mitigated, and are cleared for opening. 100%
of public right of ways cleared.
01/08/24-02/25/24
Phase II ground -level remediation performed. Ground -level cleanup of PACM
at multiple location types (schools, residential, commercial, etc.) based on survey
responses/requests from the community.
7/8/24 — 7/24/25
Hangar Fire debris removal. Cleanup of Hangar Fire -related PACM and debris
from Site — Navy Action (NAVFAC, 2026).
12/28/23
HCA public health webinar. Public webinar and public health expert panel with
representatives from USEPA, South Coast AQMD, DTSC, Drexel University,
University of California at Irvine, and CTEH to inform the community of sampling
results and response actions (HCA, 2023).
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DATE(S)POCHRONOLOGY
1/31/24
Post -Hangar Fire residential investigation webinar. Public webinar providing
information on the forthcoming residential soil, dust, and indoor air study, and how
to volunteer for the study.
02/25/24-10/30/24
Phase III ground -level remediation performed. Follow-up ground -level
cleanup over the same residential areas, as required, to remove debris mobilized by
wind and rain events, as necessary. The scope of work is identical to Phase II.
02/28/24-03/10/24
Geosyntec's residential soil, indoor air, and dust study. Outdoor composite soil
samples, indoor air, and indoor dust -wipe samples collected at 50 residential
locations within Hangar Fire -impacted "Study Area" and 30 homes in "Control
Areas" outside Tustin (Geosyntec Consultants, 2024).
07/11/24
Above -ground inspection and remediation work plan. Work Plan detailing
procedures on Hangar Fire -related PACM to be removed from roofs, gutters, and
above -ground areas in designated residential neighborhoods and schools (CTEH,
2024).
08/12/24
City completes turnover to the Navy of Site stabilization and maintenance
activities in advance of the Navy's Site cleanup
12/11/24-04/23/25
Phase IV above -ground remediation performed. Remediation and debris
removal consisting of above -ground level cleanup (roofs, gutters) of PACM at
multiple location types (residential, commercial, schools) based on survey
responses/requests from the community.
5/20/2025
USEPA issues written concurrence to the Navy that removal actions in
residential and Site areas have complied with federal response action
requirements.
6/23/25
The Navy completes fire -related debris removal at the hangar, ending the long-
term Air Monitoring Strategy approved by the EHU.
This Report summarizes the history and data obtained during emergency response actions
in residential, commercial, schools, parks, and open space areas located outside the Site.
The Report documents off -site response actions only. It is to be read in tandem with the
NAVFAC Southwest Hangar 1 Emergency Response Completion Report (NAVFAC,
2026).
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3. CONSTITUENTS OF POTENTIAL CONCERN
Based on the building materials used in the construction of the Navy North Hangar, the
EHU identified asbestos and lead as the two primary constituents of potential concern.
Extensive testing was performed during the 24-day active Hangar Fire event and for 19
months thereafter to monitor for any exceedances of residential health screening levels
for lead or asbestos fibers in air, soil, and dust potentially related to the event.
3.1 Asbestos
Historically, asbestos is a common component of many building materials, including attic
and wall insulation, dry wall joint compounds, vinyl flooring, heated piping insulation,
acoustic textured ceiling coatings, roofing, and siding in homes constructed prior to 1977
(USEPA, 2023a; Consumer Product Safety Commission [CPSC], 2024). Furthermore,
asbestos is a naturally occurring mineral found in altered mafic and ultramafic rocks (Van
Gosen, 2007). These minerals are present in California geologic formations and have
been historically mined throughout California. The California Air Resources Board
(GARB) provides additional information about naturally occurring asbestos in California,
noting that when rock containing asbestos is broken or crushed, asbestos fibers may be
released and become airborne (CARB, 2024a). As a result, background air samples
commonly contain sporadic airborne asbestos fibers, even in environments without
manufactured ACM.
3.2 Lead
Lead is a ubiquitous metal that occurs naturally within the environment. Lead was also
used extensively within the United States until the 1970s as an additive in gasoline, and
motor vehicle exhaust was a major historical source of lead emissions into the air and soil
(CARB, 2024b). Current uses are primarily associated with lead -acid batteries and
certain aviation fuels (ATSDR, 2020). Furthermore, lead has been used as a stabilizer
for paint and was commonly used until 1978; potentially 87% of homes built before 1940
contain lead -based paint (USEPA, 2023b).
Lead exists at background levels in Southern California. In 2020, a study of 1,173
samples of lead were collected from shallow soil in residential areas in the City of Santa
Ana, northwest of the Navy North Hangar Site, with a reported mean concentration of
128.4 parts per million (ppm), with a maximum concentration of 2,687 ppm (Masri et al.,
2020).
3.3 Particulate Matter
Particulate matter (PM) is a complex mixture of extremely small particles and liquid
droplets that exist in the environment, including pollen, dust, and soil. PM10 is a specific
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measurement of PM in the air, which evaluates particles that are less than 10 microns in
diameter. The average concentration of PM10 is a measure of air quality that is measured
on the PM10 air quality index (AQI). The AQI for each category (presented below) is
based on Table 2 of Section 3.4 of Appendix G — Breakpoints for the AQI of USEPA 40
Code of Federal Regulations (CFR) Parts 50, 53, and 58 (USEPA, 2024).
Good Moderate Unhealthy for Unhealthy Very Un ea y ..us
(0 to 54) (55 to 154) Sensitive Groups (255 to 354) (355 to 424)
54)
(PPm(Pp m) ) (PPm) (155 to(pPm) (PPm) I ..
PM10 AQIs
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4. RESPONSE ACTION SUMMARY
Operating as the Navy's Response Action Contractor, the City coordinated the
implementation of a series of studies to evaluate the nature and extent of Hangar Fire -
related particulates and burn debris found in off -site residential, commercial, school, park,
and open space areas. The City also coordinated ongoing monitoring of air quality, soil,
and dust by City subcontractors and operated in cooperation with various agencies
participating in the EHU. The City implemented removal actions of Hangar -Fire -related
debris at locations off Site. These off -Site actions are summarized below:
4.1 Air Monitoring
Regulatory agencies and City subcontractors performed extensive 24/7 air monitoring
beginning within hours of the start of the Hangar Fire, and that monitoring was expanded
and continued for approximately 19 months after the Hangar Fire to evaluate the potential
for wind -distributed contamination. USEPA, South Coast AQMD, and the Navy
primarily managed the scope, duration, goals, and test methods for air sampling and the
chosen location of monitors.
The EHU evaluated thousands of air samples for the presence of asbestos fibers,
particulate matter, volatile organic compounds (VOCs), and toxic metals such as lead and
arsenic. Samples were collected from around the Site perimeter and at up to 25
monitoring stations established throughout the surrounding residential communities
(Figure 3).
The following wind rose diagram, based on data from the Santa Ana John Wayne Airport
weather station,' depicts the frequency of wind speeds and wind direction between
November 7, 2023, through December 1, 2023. The data show that the primary wind
direction during the Hangar Fire event was from the south-southwest, but there were
substantial reversals of wind direction, with periodic strong winds from the northeast
during Santa Ana conditions. The EHU monitored these wind conditions throughout the
event and considered the proximity of residential communities to the Hangar Fire and
prevailing wind directions when establishing the air monitoring strategy.
' https://www.weather.gov/wrh/timeseries?site=KSNA
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N
NNW NNE
NW NE Wind Sped i +1
'oVNW ' ENE 0 i
e -
0 13-19
vV E • 19-2a
• 25-32
WSW ESE
SW SE
SSW SSE
Wind Rose Diagram'
4.1.1 Air Toxic Metals Monitoring (November 10, 2023 —May 14, 2024)
From November 10, 2023, through May 14, 2024, multiple agencies performed
continuous daily air quality monitoring around the Site perimeter and at approximately
23 stations established throughout the surrounding residential communities to provide
real-time information on ATMs in the air.
The EHU evaluated over 3,200 air samples for a full range of metals over the course of
this monitoring effort. The full list of evaluated metals included:
Antimony
Arsenic
Barium
Bei llium
Cadmium
Chroltiium
Cobalt
Copper
Lead
Molybdemun
Nickel
Seleniiun
Silver
Thallitun
Vanadiinn
Zinc
Sampling pumps were used to pull an average of over 1,400 liters of air through a media
filter for each ATM sample, thereby concentrating airborne particles over a period of
' The wind rose diagram displays prevailing wind patterns. The direction of each "spoke" indicates the
direction wind blew from and the length of each spoke around the circle represents the frequency of wind
from that direction. The colors of each spoke indicate the speed, in miles per hour, of the wind from each
direction. Data were collected from the Santa Ana John Wayne weather station between November 7,
2023, and December 1, 2023.
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approximately 12 hours. The EHU collected the daily ATM results and compared them
to the USEPA National Ambient Air Quality Standard (NAAQS) for lead and the
California Office of Environmental Health Hazard Assessment's established health -based
thresholds for level of concern for arsenic and other metals. This Report summarizes the
ATM results in Table 1 and compiles the electronic copies of the daily ATM reports in
Appendix B.
Lead was detected in 15 of 3,239 samples collected between November 10, 2023, and
May 14, 2024, at concentrations ranging between 0.012 and 2.7 micrograms per cubic
meter (ug/m3). The NAAQS for lead is a 3-month rolling average concentration of less
than 0.15 ug/m3. Lead was detected above 0.15 ug/m3 in only localized areas on five
days over the 17-month monitoring period:
• November 14, 2023: 1 of 7 samples
• November 15, 2023: 5 of 17 samples
• November 16, 2023: 1 of 37 samples
• November 17, 2023: 1 of 50 samples
• December 15, 2023: 1 of 20 samples
4.1.2 Air Particulate Monitoring (November 16, 2023 - April 30, 2025)
From November 16, 2023, through April 30, 2025, the City and EHU performed daily air
quality monitoring around the Site perimeter and at approximately 23 stations established
throughout the surrounding residential communities to provide real-time information on
PM in the air. Sampling teams collected over 10,200 air PM10 measurements over the
course of this 18-month monitoring effort. The EHU then recorded and compared daily
average PM 10 air readings against the typical range of air particulates for the area.
The monthly air particulate results are summarized in Table 2, and electronic copies of
the daily air PM reports are provided in Appendix C. The average background PM10
concentration for the Tustin area is approximately 26 ug/m3, based on the six-month
period of monitoring by South Coast AQMD in Anaheim, California before the Hangar
Fire. Anaheim is the closest available long-term South Coast AQMD dataset to the Site.3
The air particulate data obtained by the monitoring network around the Site met the
National Air Quality PM10 Standard, i.e., no exceedance of 150 ppm more than once per
'https://xappp.aqmd.gov/aqdetail/AirQuality4listoricalData
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year on average over a three-year period.4 Of the 10,248 PM10 samples collected, the
average monthly and overall PM10 concentrations throughout the 18-month monitoring
period post -Hangar Fire were consistently within the "good" air quality range (below
54 ppm). Over the 18-month monitoring period, a reading of 154 ppm was recorded only
once, on January 1, 2025. South Coast AQMD representatives have confirmed that poor
air quality is common on January 1, July 4, and July 5 due to firework events around these
dates.
4.1.3 Asbestos Air Monitoring (November 7, 2023 - June 23, 2025)
The USEPA, the Navy, and the City coordinated air monitoring, with supplemental
sampling provided by South Coast AQMD around the Site perimeter and at
approximately 20 stations. Monitoring stations were embedded throughout the
surrounding residential communities to provide real-time information on the presence of
asbestos fibers in the air (Figure 3).
The EHU conducted daily air monitoring for asbestos fibers from 20 stations beginning
on November 8, 2023, and continuing until May 21, 2024 (EHU, 2024). Thereafter, the
EHU continued daily monitoring in Columbus Square Park at station DU-20 until June
23, 2025, to provide ongoing quantitative data on regional airborne asbestos
concentrations in the adjoining residential area throughout the post -Hangar Fire cleanup
and response actions.
The EHU collected over 4,800 asbestos air samples between November 8, 2023, and June
23, 2025. Laboratory reports identified confirmed asbestos fibers in four of the 4,800
total samples obtained. These detections occurred at the long-term monitoring station in
Columbus Square Park on October 26, 2024, November 4, 2024, January 20, 2025, and
June 8, 2025, with positive transmission electron microscopy (TEM) detections of one
fiber of asbestos or 20 structures per millimeter squared (s/mm2), which is below the
70 s/mm2 USEPA Asbestos Hazard Emergency Response Act (AHERA) standard for
post -abatement clearance in schools (40 CFR Part 763 Appx A., subpart E). Each TEM
sample was collected on a media filter, typically after drawing over 7,000 liters of air
through the filter.
Separately, six fibers were detected in one additional sample from Monitoring Station 13
located at the corner of Armstrong Avenue and Valencia Avenue on December 19, 2023,
using the Phase Contrast Microscopy (PCM) test method. The PCM method is designed
to identify the presence of fibers generally but cannot determine whether the fibers are
from asbestos or some other source; therefore, this detection did not confirm the presence
4 https://www.epa.gov/criteria-air-pollutants/naaqs-table
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of asbestos. Notably, 26 other samples were collected on that same day, across 16 other
surrounding stations. No fibers of any kind were identified in any of these
contemporaneous samples.
Sampling pumps were used to pull approximately 1,200 liters of ambient air through a
media filter for each PCM sample. Sampling technicians exchanged multiple filters over
the course of each day during the first six months of monitoring to provide extended
sampling coverage at key stations. The identification of single asbestos fibers in less than
0.1 % of air samples collected over a nearly two-year period, all at concentrations below
risk -screening levels, is consistent with natural background conditions. This Report
summarizes the asbestos air results in Tables 3 through 5, and the electronic copies of
the asbestos air reports are provided in Appendix D.
4.1.4 Ambient Air Monitoring (November 2023)
South Coast AQMD collected three ambient air samples on the day that the Hangar Fire
started (November 7, 2023), using a Silco Canister for 15-second sampling. One sample
was collected in an upwind area at the Orange County Sheriff's Regional Training
Academy, and two samples were collected in the downwind area at Columbus Square
Park and Great Foundation Montessori School. All three locations are approximately
1,500 feet from the Site. South Coast AQMD analyzed these samples for VOCs using
USEPA TO-15 analysis. Although several VOC constituents were detected in the three
ambient air samples, South Coast AQMD noted that all detected VOCs were within
common background concentrations (EHU, 2023). Ambient air laboratory reports are
provided in Appendix E. After November 7, 2023, City subcontractors performed
further monitoring for VOCs around the Site. The laboratory reports show seven
intermittent detections, all within common background levels. Between November 15,
2023, and December 18, 2023, South Coast AQMD collected over 2,000 additional real-
time monitoring readings, with no further VOC detections (EHU, 2023).
4.2 School, Park, and Public Areas Assessments and Clearances (November —
December 2023)
From November 9 through December 27, 2023, HCA and USEPA collected soil and dust
samples at schools, parks, and public areas surrounding the Site. The progressive
sampling and clearance of the parks and schools by HCA were communicated to the
public through daily incident update reports (Appendix A). HCA and USEPA collected
24 soil samples to evaluate lead and/or metals concentrations at multiple locations within
the Tustin community adjacent to the Site. The concentrations of detected metals,
including lead, in all samples fell below residential screening levels or were within typical
background concentrations. Sampling locations included Heritage Elementary, Legacy
Magnet Academy, Orange County Sheriff's Regional Training Academy, Montgomery
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Square Park, Orange County Rescue Mission, Columbus Square Park, and Arlington Park
(HCA, 2024).
On November 11 and 13, 2023, a debris screening and assessment was performed at
Magnolia Tree Park. Samples of PACM debris in exterior park areas and TEM micro -
vacuum samples were collected from on -site restroom interiors. Two of the interior dust
samples from the women's restroom contained asbestos fiber concentrations above
typical background concentrations, while the men's restroom sample was within the
range of typical background. The women's background was decontaminated by a third -
party asbestos remediation contractor.
On November 12, 2023, PACM debris, TEM micro -vacuum dust, and PCM air samples
were collected from the Tustin Family and Youth Center. Above -background
concentrations of asbestos fibers were identified in three of the five micro -vac dust
samples. Similar to Magnolia Tree Park, these areas of the Tustin Family Youth Center
were decontaminated, and no asbestos fibers were detected in the confirmation sampling
conducted on November 30 (Appendix F).
USEPA collected an additional 15 soil samples on December 27, 2023, from Columbus
Square Park, Montgomery Square Park, and Arlington Park and analyzed the samples for
various metals, including antimony, arsenic, barium, beryllium, cadmium, chromium,
cobalt, copper, lead, molybdenum, nickel, selenium, silver, thallium, vanadium, and zinc
(HCA, 2024). The concentrations of detected metals, including lead, in all samples fell
below residential screening levels or remained within typical background concentrations.
HCA sampled dust on various surfaces in the community. During this initial two -month
period, 38 dust samples obtained from various surfaces in the community near the Site
were analyzed for lead. Lead concentrations in these dust samples were below the
residential screening level for lead in dust. Sampling locations included Heritage
Elementary, Legacy Magnet Academy, Orange County Sheriff's Regional Training
Academy, Montgomery Square Park, Orange County Rescue Mission, Columbus Square
Park, and Arlington Park (HCA, 2024). An electronic copy of the full report is provided
in Appendix F.
4.3 The Four Phases of the Navy North Hanzar Fire Emergency Remediation.
The massive emergency response to the Hangar Fire evolved over time and can be fairly
segregated into four "phases." Phases I through III focused on ground -based remediation
work and took place primarily over the 14-month period between November 2023 and
December 2024. The fourth phase occurred over four months and focused on above-
ground recovery work because remnants of Hangar Fire -related debris persisted on
above -ground structures (for example, roofing on school and residences). The City, the
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Navy, and the EHU all agreed that it would take an unreasonable amount of time for
residual Hangar Fire debris to eventually dislodge itself through natural weather
conditions and become recoverable on the ground. Unless more proactive actions took
place, remediation teams would need to remain mobilized indefinitely. Accordingly, the
above -ground work aggressively pursued the last remnants of the Hangar Fire debris that
were both accessible to crews and not already recovered during the earlier 14 months of
ground -based work.
Phase I of the ground -based emergency response spanned the initial two -month period of
the active Hangar Fire through the OCFA's December 5, 2023, post -fire turnover of
command operations to the City and its emergency response coordinator, IEM.
The City and IEM managed the lowering of damaged Navy North Hangar doors and the
encapsulation of debris at the Site with a tackifier. Thereafter, the Navy took over
operations at the Site in mid -July 2024. The so-called "Incident Management Team
(IMT)" of Phase I would become after turnover the multi -agency "EHU" of Phases II
through IV, and the OCFA-led "Incident Command Center" would become the City's
and IEM's command center. Phase I was driven almost exclusively by hour -by -hour
decision -making and crisis management, and it focused on removing, under 24/7 work
schedules, enormous amounts of Hangar Fire debris on public roads, parks, and schools
to restore basic civic functions and public safety. Phase I also involved intense efforts to
test and evaluate air, soil, and debris to understand, during the initial days, the basic public
health risks facing the emergency response teams.
Phase II involved the next two -month period, during which the City's subcontractors
assumed daily management of the ground -based remediation and triaged tasks with more
information in hand and with more available resources. Decision -making shifted to day-
to-day strategic thinking and less hour -to -hour crisis management. During Phase II, IEM
developed early -stage protocols to oversee the daily assignments of large remediation
crews and teams of CACs to target debris recovery on a neighborhood -by -neighborhood
and property -by -property basis. Phase II's focus expanded into residential areas and
private properties. Phase II prioritized more targeted cleanups to allow the most -impacted
communities to recover sooner and reopen schools, parks, and businesses earlier.
Phase II continued to recover significant amounts of Hangar Fire debris.
During Phases I and II, the City and its subcontractors also took interim measures to
stabilize the destroyed Navy North Hangar structure and the tons of fire debris. The threat
of winds and winter storms made the toppling of the severely damaged 120-foot-tall Navy
North Hangar doors and the potential off -site migration of debris a significant
risk. Primarily in the first few months, the City took steps to hire crews and heavy
equipment to lower and dismantle the severely fire -damaged nested sliding Navy North
Hangar doors, apply a specially designed tackifier ("Gorilla Snot") to encapsulate the fire
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debris in place and install a protective plastic barrier around the entire Navy North Hangar
footprint until the Navy's contractors could be mobilized for on -site longer -term
cleanup. The complete turnover of City/IEM stabilization operations at the Site itself to
the Navy and its subcontractors for cleanup occurred in July 2024.
Phase III did not have any deadline in mind; rather, it would conceptually last until the
regulators concluded "enough was enough." Phase III spanned the longest period of time
to perform ground -based work (10 months), and it remained active until reports from the
public to the City of uncollected fire debris stopped completely and the amount of
recovered ground -based debris became incrementally smaller and smaller, to the point of
insignificance. During Phase III, IEM honed and further developed its operational,
reporting, and management protocols in furtherance of efforts to make daily assignments
for remediation teams and target areas and residences that needed initial and additional
rounds of cleanup. The City and its subcontractors did not terminate Phase III until public
reports of ground -based debris ended completely and mobilized crews became
increasingly idle because they had no additional reported debris to recover on the ground.
In collaboration with the EHU, during the last months of 2024, as the amounts of daily
collected ground debris started to become negligible, the City began asking the EHU the
relevant question facing the emergency response effort, "When should emergency
response crews demobilize?" The question was important because the catastrophic
Hangar Fire was unprecedented and no operational or closure template existed anywhere
in the country. The City tasked IEM to evaluate the risk of future migration of residual
Hangar Fire debris located in elevated locations, such as on school and residential roofing.
Upon spot inspection of schools and various residences in January and February 2024,
IEM found evidence of small amounts of debris in certain roofs and gutters. On February
28, 2024, DTSC issued recommendations for development of a workplan to remove the
remaining debris on above -ground structures as a proactive measure (Appendix K).
Working with the EHU over the next several months, the City and its environmental
consultants devised a "Phase IV" work plan to perform four additional months of above-
ground remediation to mitigate the risk of future migration of residual Hangar Fire debris.
The EHU concurred that, once the City's Phase IV above -ground remediation work plan
was performed satisfactorily, the emergency response effort would be logically complete,
and conditions within the impacted areas would be sufficiently protective of human health
and the environment.
4.4 Ground Remediation Overview (November 2023 — December 2024)
The City and its subcontractors implemented three major ground -level remediation
responses (Phases I, II, and III) over a 13- to 14-month period. The initial response
(Phase I) emphasized basic safety and stabilization, and it rapidly established a process
for community members to report the presence of potential Hangar Fire -related debris.
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Phase I lasted for approximately seven weeks. In Phase II, the City and IEM modified
the survey request form to include an on-line consent form for private property access,
enabling property access for cleanup crews without owner presence. Phase II lasted for
approximately eight weeks. Phase III remained active and provided ongoing ground -
level response and cleanup teams for the remaining 10 months and until completion of
the last -stage remediation (i.e., Phase IV's above -ground remediation). Between
February and December 2024, with each successive phase of cleanup, the number and
frequency of debris observations, inspections, and the daily volume of PACM recovered
significantly decreased.
Trained emergency response workers appropriately bagged, secured, and relocated all
PACM debris waste recovered from residential, commercial, school, and other off -site
areas to a designated staging area (Buildings 20A and 161), located near the former Navy
North Hangar footprint. The Navy temporarily stored the collected PACM debris along
with Navy North Hangar structural debris, pending final disposal by the Navy at a
licensed off -Site facility in accordance with applicable regulatory requirements.
The City removed a total of 737 tons of Hangar Fire -related debris during the multi -phase
remediation. This Hangar Fire -related debris included identified fragments of wind-
borne materials from the North Hangar, mulch, and ground covering containing North
Hangar structural debris/fragments, as well as outdoor furniture/equipment impacted by
PACM. Waste manifests are presented in Appendix G. The following sections
summarize activities completed by the City and its subcontractors during each of the three
ground -level response action phases.
4.4.1 Phase I Ground -Level Remediation Response (November 7, 2023 — January
12, 2024)
The initial two -month response, known as Phase I, occurred between the start of the
Hangar Fire on November 7, 2023, and continued through January 12, 2024. The
immediate days after the fire commenced focused on crisis management and public
safety, including locating and hiring qualified hazardous materials subcontractors. The
initial priorities were to restore basic civic functions like road usage and clean Hangar
Fire debris from public roads, parks, and schools. Within the first two weeks, the City
formally established a process for community members to self -report to the City and
request cleanup if Hangar Fire -related debris was observed on their properties or
elsewhere.
The OCFA led the Incident Response Command until December 5, 2023, after which
command transferred to the City and IEM. Among its early tasks, the City/IEM team
hired the crews and heavy equipment necessary to lower and dismantle the severely
damaged Navy North Hangar doors and apply tackifier to encapsulate the ash and debris
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at the Site until the Navy could hire its own contractors to complete debris removal at the
Site.
During the Phase I response period, the City mobilized over 600 environmental response
personnel from across the country to support the field inspection and debris recovery in
the 12 OCFA "Divisions." CACs inspected and cleared a total of 1,524 locations by
trained asbestos removal workers during an approximate seven -week period (218
requests per week on average) at no cost to owners/occupants (Figure 4). To be
conservative, EPA deemed and treated all Hangar Fire -related debris as PACM.
Appendix H presents a table summarizing Phase I locations. The OCFA and the City
rapidly established a procedure for the public to report debris sightings and coordinate
response actions. The City later refined this procedure over the course of subsequent
phases. The Phase I ground -clearance process involved the following general steps.
(1) Inspection/Cleanup of Public Areas and Publicly Reported Hangar Fire Debris:
City subcontractors performed a comprehensive inspection and cleaning of
streets and public areas such as parks, sidewalks, and schools while the City
took initial steps in parallel to establish a web -based survey request form and
performed door-to-door canvassing in the most impacted areas, to perform
cleanup at no cost to the owners/occupants. City subcontractors accomplished
this canvassing, accompanied by City employees, to acquire consent for
exterior, ground -level inspection, and, as necessary, remediation. During this
Phase, the City received approximately 1,618 reports of Hangar Fire debris.
Response areas included schools, public agencies, public rights -of -way, parks,
residential, and commercial locations. A subset of the initial inspection requests
(approximately 6% of the overall respondents) declined to sign the consent form
or were unable to be contacted to provide access to the location or private
property after multiple attempts. The inspection teams identified these locations
as "declined," and no inspection or removal actions occurred at those discrete
locations.
(2) Remediation: A third -party asbestos abatement subcontractor (ATI) completed
ground -level remediation for each location where an owner's signature consent
and temporary access rights were obtained and in public areas such as parks,
sidewalks, streets, and schools. The City notified residents once the inspection
and removal work was complete.
(3) Clearance Inspections: A separate third -party CAC completed an inspection of
areas remediated and confirmed in writing completion of abatement of all
PACM. Note that no laboratory testing was conducted on debris collected,
given that remediation was conducted under the conservative assumption that
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all Hangar Fire -related debris would be deemed PACM, and it was managed
and disposed of consistent with that assumption.
(4) Close Out: Depending on when the Phase I work was performed before or after
the active fire event, an IMT or IEM representative then reviewed the field
reports to ensure the required steps had been completed and documented for
each location. IEM managed an emergency response database.
4.4.2 Phase II Ground -Level Remediation Response (January 8, 2024 — February
25, 2024)
Phase II included the following four -step process between January 8, 2024, and February
25, 2024. During the Phase II response period, the City modified its inspection request
portal to include an on-line consent form for property access, so that all reported locations
of fire -related debris (presumed PACM) could be accessed and remediated by available
crews. City subcontractors inspected and cleared a total of 273 locations at no cost to the
owners/occupants during Phase II, over an 8-week period (35 requests per week on
average) (Figure 5). Appendix I presents a table summarizing Phase II locations.
(1) EPIC On -Line Request Form: For this phase, IEM created an enhanced
electronic tracking on-line request form to track all four steps of the ground -
level response workflow. This tracking system documented requests from
owners, occupants, and interested parties, the work performed, and clearances
for targeted schools, parks, residential, commercial, public locations, and public
rights -of -way.
(2) Remediation: A third -party asbestos abatement subcontractor (typically, ATI)
completed ground -level remediation of all areas where owners or the occupants
provided written consent. Due to wind and other weather -related factors,
abatement subcontractors visited some addresses more than once, as PACM
occasionally became mobilized from roofs and other elevated areas after an
initial round of ground -based remediation. This mobilization of debris was
observed most frequently after Santa Ana wind events. The City notified
residents once the Phase II removal work was complete.
(3) Clearance Inspections: A third -party CAC completed a visual inspection of the
remediated areas and, if the Phase II work was satisfactory, the CAC confirmed
in writing the abatement of all PACM. Note that no laboratory testing of
collected debris was conducted because remediation teams applied the
conservative assumption that all recovered debris was deemed to be PACM.
As an added measure of quality assurance/quality control (QA/QC), a separate
third -party CAC visited at least 20% of the targeted Phase II locations after the
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first CAC had cleared the location to confirm that the first CAC's evaluation
was correct and confirm accuracy and compliance with clearance protocols.
(4) Administrative Close -Out of Phase II: An IEM representative then reviewed all
field documentation to ensure that the required steps had been completed for
each of the 273 locations targeted for remediation, and IEM documented these
completed steps in a management database.
4.4.3 Phase III Ground -Level Remediation Response (February 25, 2024 -
December 11, 2024)
Phase III informally commenced on approximately February 25, 2024, and this 10-month
phase focused on targeted areas located farther from the Site. Ongoing inspection and
remediation support occurred for locations previously targeted during Phase II where
additional debris became mobilized from weather events, such as seasonal rains and Santa
Ana winds. This extended stage of the remediation effort also allowed for follow-up
work in areas of the community where crews operated during the first four months of the
ground -level remediation response (i.e., Phase I and Phase II).
The Phase III ground -level response occurred during the period between February 25,
2024, and December 11, 2024, and it followed the same basic procedures and protocols
applied in the Phase 11 response work until public reports of debris essentially stopped
and the amount of daily recovered debris became insignificant. City subcontractors
inspected and cleared a total of 204 locations (Figure 6) from the 208 people who
requested and reported additional Hangar Fire debris during Phase III. Phase III's
ground -level cleanup included a total of 204 inspections over the 10-month period (fewer
than five requests per week on average). The owner/occupant did not provide consent
for the remaining four respondents. Appendix J presents a table summarizing Phase III
locations.
4.5 Phase IV Above -Ground Remediation Response Activities (December 11, 2024
— April 23, 2025)
During January and February 2024, IEM and other certified contractors performed
inspections of various school and apartment roofs within the impact areas and found
remnants of Hangar Fire debris. The City's subcontractors prepared an above -ground
remediation work plan that was approved by the EHU. The work plan recommended
above -ground inspections of structures in areas surrounding the Site. Inspections of roofs
and gutters at various locations, including two neighborhoods within Division C, seven
TUSD schools (Heritage, Legacy, Beswick, Hillview, Sycamore, Tustin High, and
Nelson), the Annex at Tustin Legacy, Columbus Square Community Center, and OCFA
Fire Stations 21, 26, and 79, were conducted to support the need for additional
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remediation. The results of the above -ground inspections are outlined in an Exterior Top -
Down Inspection Evidentiary Package, dated February 16, 2024 (Appendix K). The
inspection identified visible Hangar Fire -related debris and PACM on approximately half
of the home rooftops, all seven TUSD school rooftops, the rooftops of the Annex at Tustin
Legacy, the Columbus Square Community Center, and the three OCFA Fire Station
rooftops inspected.
On February 28, 2024, DTSC sent a letter to the EHU following its review of the Exterior
Top -Down Inspection Evidentiary Package (DTSC, 2024), stating the following:
"Based on DTSC's review of the [IEM January 26-February I Inspection]
Report, it is apparent that fire -related debris and suspected ACM still exists on
above -ground structures. DTSC acknowledges that while fire -related debris
and suspectedACMmay have been previously mitigated, ongoing mitigation of
debris may be required to ensure that remaining debris is recovered
appropriately. DTSC recommends that an implementation plan be developed
to remove remaining debris on above -ground structures as a proactive measure
to preventfuture reoccurrence of impacts from these materials. " (Appendix K)
In short, the above -ground inspection results indicated that PACM and Hangar Fire -
related debris still existed on above -ground structures in sufficient quantities to warrant
additional removal (CTEH, 2024). DTSC also stated that while Hangar Fire -related
debris and PACM may have been significantly reduced due to ground -based remediation
efforts, further above -ground efforts would be necessary to ensure that the risk of future
exposure to the debris is mitigated appropriately (CTEH, 2024). The EHU finalized
"A Work Plan for Above Ground Inspection and Remediation of Fire -Related Suspected
Asbestos -Containing Material from Designated Residential Neighborhoods and Schools"
(Work Plan) on July 11, 2024 (CTEH, 2024, Appendix K).
The Work Plan noted specific areas for expected above -ground remediation, including:
• Columbus Square, including Coventry Court;
• Tustin Meadows and Cherrywood Estates;
• Centennial and Veterans Sports Park;
• The Landing;
• Anton Legacy Apartments;
• Amalfi Apartments; and
• All Schools and Fire Stations that contained roof -level PACM upon further
inspection (OCFA Fire Stations 21, 26, and 79; TUSD schools Heritage, Legacy,
Beswick, Hillview, Sycamore, Tustin High, and Nelson).
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The objective of the above -ground remediation program was to reduce the overall mass
of Hangar Fire -related PACM on portions of structures and roofs that were readily
accessible without compromising worker safety that the EHU deemed would be sufficient
to be protective of human health and the environment. Above -ground remediation
response activities began on December 11, 2024, and they concluded on April 23, 2025,
using the following procedures and protocols in OCFA Divisions A, B, C, E, U, V,
and W:
(1) Community Outreach: The City and IEM developed a public outreach strategy
to announce the availability at no cost to residents of the above -ground
inspection and debris removal program, which was implemented on a voluntary
basis. Initially, notices of the inspection program were provided through City
mailers to individual residents in the targeted OCFA Divisions. As a second
notice, the City followed up on these informational mailers with door hangers
at homes located within the targeted Divisions by IEM and ATI. IEM and ATI
performed additional door-to-door and face-to-face daily interactions with area
residents once the above -ground equipment mobilized in neighborhoods and
cleanup began. Moreover, the City placed notification signs around the
community with QR Codes as a Public Notice for the community to sign up for
above -ground inspections and removals.
(2) Pre-Remediation Inspections: An asbestos remediation subcontractor
performed a visual inspection of identified elevated locations, structures, and
surfaces to determine the presence of visible PACM debris utilizing scissor lifts,
boom lifts, ladders, and/or scaffolding. The asbestos remediation subcontractor
included photographs of physically accessible above -ground structures such as
roofs, gutters, and porches in their inspection. Inaccessible and potentially
unsafe elevated areas were excluded. Appendix L presents photos of typical
above -ground structures evaluated during inspection activities. A total of 408
locations were inspected, and PACM was identified at 282 of these locations.
(3) Remediation: Following the pre-remediation inspections (Figure 7), qualified
and trained emergency remediation personnel removed PACM using
appropriate personal protection equipment in accordance with the procedures
established in the Work Plan (CTEH, 2024). Asbestos inspectors observed and
documented the remediation activities. The asbestos remediation contractor did
not permit remediation teams to mount or step on pitched rooftops or roofs with
breakable tiles. These safety measures mitigated the risks associated with
falling or potential damage to roof tiles and gutters.
Where necessary, the remediation teams used High -Efficiency Particulate Air
(HEPA) vacuums equipped with extensions that allowed teams to reach and
remediate portions of roofs that could not be directly reached from booms, lifts,
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ladders, or scaffolding. Remediation teams also used wet methods throughout
the process of collecting debris. Remediation activities proceeded from the top
of the location (e.g., rooftop, gutters) downward, removing Hangar Fire -related
PACM located on windows, windowsills, balconies, awnings, and other
horizontal above -ground surfaces. The City notified residents once the removal
work was complete.
(4) Post-Remediation Inspection: Upon completion of PACM removal for a
specific location, a CAC performed a visual post-remediation inspection to
determine if additional above -ground remediation would be needed and to
document the completion of the work per the Work Plan objectives. IEM
documented completion of the removal activity in the project -tracking database.
(5) Post-Remediation Quality Control: A separate CAC firm independently re-
inspected a minimum of 20% of remediated above -ground locations to confirm
remediation completion. The independent CAC would document each
reinspection using a Quality Control Visual Inspection Checklist. If the second
CAC identified the need for additional PACM removal, remediation personnel
would be re -mobilized to remediate the area of concern. A summary of the
completed record of inspections and follow-up QC re -inspections are presented
in Appendix K.
(6) Recovered Debris Disposal: Per USEPA guidance, the collected debris was
deemed to be PACM and placed into plastic bags, then double -bagged and
goosenecked for transportation and disposal in accordance with standard
asbestos abatement practices. All PACM debris waste was secured and
relocated to a designated staging area (Buildings 20A and 161), located near the
former Navy North Hangar footprint. The Navy properly disposed of hangar
fire debris waste, in accordance with applicable regulatory requirements at an
appropriate off -site disposal facility. Waste manifests are presented in
Appendix G.
Per the EHU-approved Above -Ground Work Plan, this Report serves as the Post -Cleanup
report for the above -ground debris removal. Accordingly, this Report is submitted to the
EHU to document and demonstrate that all above -ground remediation operations have
met the objectives outlined in the Work Plan.
4.6 December 2023 HCA Webinar
On December 28, 2023, HCA hosted an informational webinar for the community
comprised of regulators (USEPA, DTSC, South Coast AQMD, and HCA) and outside
public health experts (Drexel University and UC Irvine) to inform the public of the health
risks arising from the Hangar Fire. The HCA Webinar discussed the available data and
asked for the opinions of Dr. Arthur Frank from Drexel University (Professor of Public
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Health and Medicine), Dr. June Wu of UC Irvine (Professor of Environmental and
Occupational Health), and Dr. Oladele Ogunseitan of UC Irvine (Distinguished Professor
of Population Health and Disease Prevention). These outside public health experts
concluded that the Hangar Fire did not expose residents to long-term health risks. See
"Tustin Hangar Fire Expert Panel Discussion," found at
https://www.youtube.com/watch?v=AD1x7LabONg (Dr. Frank, minutes 26-35; Dr Wu,
minutes 36-44).
Dr. Andrea Polidori of South Coast AQMD described his agency's initial mobilization,
air quality monitoring, and debris sampling that began within hours of the start of the
Hangar Fire and continued from November 7 through November 12, 2023.
Ben Castellana of USEPA Region 9 described USEPA's initial efforts to ramp up long-
term air monitoring stations, beginning with four stations monitoring for airborne
particulates, metals, and asbestos from November 8 through November 12, 2023. The
number of stations quickly escalated as additional monitoring resources and sampling
teams became available. By the end of the week of November 12, 2023, USEPA had
coordinated the mobilization of a total of 33 air monitoring stations around the Site and
throughout the community. These monitoring stations were then turned over to City and
Navy subcontractors to continue long-term monitoring efforts.
Dr. Christopher Kuhlman, a Diplomate of the American Board of Toxicology and board -
certified industrial hygienist from CTEH, summarized the air testing results through
December 18, 2023. Dr. Kuhlman highlighted the available data from asbestos and lead
air sampling and made the following observations:
Asbestos
"There have been no detections of asbestos in the air. More than 900 24-hour samples
have been collected and analyzed from the Hangar Site and the surrounding community,
with no asbestos detected in any of these samples. This is really reassuring considering
that the air is the most important route of exposure for asbestos, compared to asbestos
that can be embedded in solid materials and debris. "
Lead
"Of the more than 700 samples that were collected for lead in the air, there were 10
detections. Six of these ten detections were observed at the air testing station positioned
closest to the Hangar. "
Dr. Frank, trained in internal medicine and occupational medicine, provided context for
the interpretation of asbestos data, expected background concentrations, and the
difference between background asbestos exposure and long-term occupational exposure.
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"Because asbestos is both a naturally occurring mineral and, in the past, literally
millions of tons of it has been used, asbestos is everywhere. There is no place on this
earth that you can't find asbestos and that you won't find it in the air. For example,
scientists have shown that at the polar ice caps you can drill down and you can find
asbestos. "
"In a lifetime, a 70 year lifetime, any individual might take in three to four million fibers
of asbestos. No one has ever shown that this level of exposure has caused any disease.
This is a level that we consider background and with the testing that you've heard about
there's no additional fibers. "
"What [find encouraging, and I am someone who has made a career of studying people,
not with this level of exposure but with higher levels... is that I would not be concerned
with data that we have [and] that there is [not] going to be any risk to folks in the
community. "
Dr. Wu presented her research regarding background lead concentrations in soil in the
vicinity of Santa Ana and Tustin. She described the soil lead concentrations expected in
naturally occurring soils, as well as more elevated concentrations observed regionally due
to historical combustion of leaded fuels and lead paint use. Dr. Wu highlighted that lead
generally occurs naturally at concentrations ranging from 15 ppm to 40 ppm. In the
testing performed by USEPA at school sites throughout Tustin, the maximum
concentration was less than 25 ppm, well within the range of typical background soil.
Dr. Ogunseitan discussed his interpretation of the metals and VOC data collected
throughout the Hangar Fire. He stated that while the types of material involved in the
Hangar Fire had the potential to release VOCs or metals when burned, the monitoring
data collected throughout the Hangar Fire reflected very low concentrations.
"The data that I saw on the slides tonight showed either zero levels measured or very,
very low levels... So the data are reassuring that there is no longer ongoing contamination
and risk to the population in the neighborhoods. "
Dr. Regina Chinsio-Kwong, County Health Officer with HCA, summarized the data,
concluding that it was safe for area residents to return to normal activities, and that the
City would be sponsoring additional residential soil, indoor air, and indoor dust testing
by Geosyntec in early 2024. Eileen Mananian from DTSC then summarized the next
steps the Navy would be taking to deconstruct and remediate the Site under DTSC
oversight.
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4.7 Residential Exterior and Interior Public Health Study (January 31, 2024 -
March 10, 2024)
After the HCA webinar on December 28, 2023, the City authorized a focused public
health study to assess Hangar Fire impacts. Between January 31 and March 10, 2024, the
City initiated a residential study to assess public health risks to households and, more
specifically, determine the extent of lead and airborne asbestos fibers present within and
outside the homes most impacted by the Hangar Fire. The residential study evaluated
whether lead and airborne asbestos existed above state and federal screening levels in
residential soil, household dust, and interior air, and, if so, whether those exceedances are
potentially associated with ash or soot from the Hangar Fire (Geosyntec Consultants,
2024).
Geosyntec obtained a total of 88 outdoor composite soil samples, 640 indoor dust -wipe
samples, and 160 indoor air samples from 80 "Study Area" (Tustin, downgradient of the
Navy North Hangar) and "Control Area" (Santa Ana, Irvine) residential locations using
four separate two -person sampling teams. Each location in the study required
approximately three to four hours to test, and each team was scheduled to complete two
locations per day. The statistical analysis of these samples showed no detections of lead
or asbestos in either the Hangar Fire -impacted Tustin residences or outdoor locations
above regional background levels or regulatory screening criteria.
Geosyntec distributed a public notice community flyer to a total of 14,932 residential
homes within the City (known as the "Study Area") and the Cities of Santa Ana and Irvine
(known as the "Control Area") to identify volunteers. A total of 80 residences were
randomly selected from the pool of volunteers who responded to the community notice.
Samples were collected from each selected residence of outdoor soil, indoor dust, and
indoor air. Electronic copies of the public notice community flyer, the asbestos, lead, and
combustion laboratory analytical data tables, and an electronic copy of the full report are
provided in Appendix M. The analytical results for the soil, dust, and air sampling led
to the following study conclusions:
Outdoor Soil (88 samples): The study involved collecting an outdoor soil composite
sample for lead and asbestos at each residential study location, requiring approximately
one hour per site. The outdoor -soil sampling process included collecting small sub -
samples of soil from two to five outdoor locations using a decontaminated stainless -steel
spoon. The sampling team collected each sub -sample from the top inch of soil in
locations of exposed soil. The number and location of composite samples for each
location depended on the lot size and area of exposed soil at each sampling site, with a
goal of obtaining a representative sample of the entire yard. The sampling team
thoroughly mixed the sub -samples from each individual site in a decontaminated
stainless -steel bowl and placed the final composite sample directly from that bowl into
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laboratory -provided jars. The sampling team then then capped each sample, labeled it
with a unique sample ID, placed it in a plastic resealable bag, logged it onto a laboratory
chain -of -custody form, and placed it in a transportation cooler. Soil samples were then
delivered for chemical analyses to LA Testing/EMSL where they were analyzed for
asbestos using the TEM method and lead by USEPA Method 6010D.
The soil samples contained no detected asbestos fibers, and a statistical evaluation
showed that the Hangar Fire did not result in a statistically significant increase in lead
concentrations in the Study Area above background concentrations in the Control Areas.
In addition, all lead concentrations in the Study Area composite soil samples fell below
state and federal screening criteria.
Composite Soil Sampling
Indoor Dust (640 samples): Indoor dust samples were collected using wipe samples and
analyzed for asbestos, lead, and combustion by-products (ash, soot, and char). Geosyntec
completed dust -wipe sampling activities at each location by first completing a visual
inspection of horizontal surfaces with dust accumulation. The sampler would place a
100-square-centimeter (cm2) template on three different horizontal surfaces within each
residence for lead and asbestos analysis and on two surfaces for combustion by-product
sampling (soot and char). Each analysis for asbestos, lead, and combustion products was
collected from a separate 100 cm2 template. After wiping each 100 cm2 area following a
standard wipe pattern, using laboratory -supplied wipe cloths, the sampler would place the
wipe sample into individual laboratory -provided bottles capped, labeled with unique
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sample IDS, log the sample onto a laboratory chain -of -custody form, and place the sample
into a cooler for transportation. Wipe samples were then delivered to LA Testing/EMSL
where they were analyzed for asbestos by American Society for Testing and Materials
Method D6480-19; lead by USEPA Method 6010D; and for combustion by-products
(ash, soot, and char) by the TEM method.
Wipe Sampling
The interior dust sampling found no evidence of elevated asbestos or lead concentrations
in indoor residential dust. There were no detections of airborne asbestos fibers inside
homes above screening criteria in either the Control or Study Areas. Lead was identified
above the residential screening level in only 1 of 240 wipe samples. As there were no
co -located detections of soot/ash/char in the home where this single positive sample was
collected, and no detection of lead in either of the other two samples from this residence,
the data do not support a finding that this single lead detection is related to the Hangar
Fire or that Tustin homes have more generally been impacted by asbestos or lead.
Indoor Air (160 samples): Indoor air was tested for the presence of airborne asbestos
fibers in each residence in the study. A CAC/Certified Site Surveillance Technician
completed indoor air sampling activities at each location by setting up an indoor air
sampling station at two different high -occupancy locations. The technician set up each
sampling station with a Bios Defender 520 Primary Flow Calibrator, a Zefon Diaphragm
sampling pump, and a 0.45-micron pore -size non -conducting mixed cellulose ester filter
cassette with backup pad and tubing. The intake hose to the cassette base was set within
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the breathing zone. The technician then turned on the pump and periodically monitored
its operation. After operating for approximately 150 minutes at 9 liters/minute, the pump
was turned off. The flow rate and cumulative run time were recorded on each filter.
Indoor air samples were then labeled with unique sample IDS, placed in plastic resealable
bags, logged onto a laboratory chain -of -custody form, and placed into a transportation
cooler. Indoor air samples were then delivered for chemical analyses to
LA Testing/EMSL and analyzed for asbestos by the TEM method following the AHERA
protocols.
Indoor Air and Wipe Sampling
Of the 160 indoor air samples collected during the study, the laboratory results identified
only one sample with any detectable asbestos structures at all, and none of the samples
contained asbestos above indoor air screening criteria. Based on these data, there is no
evidence to support a finding that asbestos concentrations in residential indoor air inside
Tustin's homes are elevated or have been affected by the Hangar Fire.
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5. CONCLUSIONS AND RECOMMENDATIONS
This Report presents a comprehensive summary of the emergency actions and remedial
activities completed by the City, acting as the Navy's Response Action Contractor,
related to the November 7, 2023, Hangar Fire. Additionally, this Report serves as the
Post -Cleanup Report for the Phase IV above -ground debris removal and is submitted to
the EHU to document and demonstrate that all above -ground remediation operations have
met the objectives outlined in the Phase IV Work Plan.
From the start of the Hangar Fire on November 7, 2023, through June 23, 2025, the City
and the Navy collaborated in a novel municipal -federal effort to respond to an
unprecedented emergency. Over the last two years, the City and the Navy successfully
divided the emergency response. The City worked to identify, inspect, and remove debris
associated with the Hangar Fire from the affected area outside of the hangar footprint and
surrounding residential, commercial, school, park, and public areas throughout the Tustin
community, and the Navy worked to address fire -related debris within the Hangar
footprint and demolish the remaining hangar structure.
The extensive program of air monitoring during and after the Hangar Fire, as well as
extensive soil, dust, and indoor air sampling throughout the community, has demonstrated
that no environmentally significant or harmful release into the atmosphere of lead or
airborne asbestos occurred related to the Hangar Fire. Working in conjunction with the
EHU (USEPA, HCA, DTSC, and South Coast AQMD), the extensive emergency
response actions coordinated by the City and the Navy mitigated potential environmental
health risks during the Hangar Fire and provided rapid, ongoing community support and
debris removal throughout the recovery and post -fire demolition period. All reasonable
actions requested of the City and its subcontractors by the EHU that have been taken to
assess, contain, and address potential impacts to the off -Site community have been
sufficiently presented to the EHU and completed.
The response actions performed by the City satisfactorily met or exceeded all Federal
Response Action requirements (USEPA, 2025b). On May 20, 2025, USEPA Region 9
issued a concurrence that the Navy and its contractors had met the requirements of the
Federal Response Action and that the USEPA Emergency Planning and Preparedness
Branch had no further concerns regarding the debris removal actions associated with the
Hangar Fire (USEPA, 2025; Appendix N).
Based on the extensive available data and the satisfactory completion of the 18-month
multi -phase remediation in the residential, commercial, school, park, and all public and
private areas within the identified impact areas of the Hangar Fire, environmental
conditions are sufficiently protective of human health and the environment.
Demobilization of the City's response team is appropriate. Geosyntec concludes and
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recommends to the EHU that no further off -Site actions outside the Hangar footprint
related to the Hangar Fire are necessary, required, or warranted within the off -site areas,
including the residential, commercial, park, public property, or open space areas.
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ATTACHMENT 3
(References)
https://webdocs.tustinca.org/WebLink/DocView.aspx?id=870020&dbid=0&repo=TUSTIN