1 Clerk Mailbox
From: Nikki Kolhoff <[email protected]>
Sent: Tuesday, September 22, 2026 2:41 PM
To: Clerk Mailbox
Cc: Heidi von Tongeln
Subject: Fw: City Council 9/22/26 - Item 7A - CEQA Exemption is not Appropriate for Contaminated Business Park Development
Attachments: 2026-04-07 CoSM Letter to RWQCB_Boeing Soil Management Plan_040726_FINAL.pdf; 2026-06-24 SCP 0130B_Boeing SM_Response to Friends of Sunset Park_06_24_2026 _Final.pdf; 2026-03-19 Friends of Sunset Park Letter 3_19_2026.pdf; 2026-08-11 City Response to FOSP re CEQA exemption for business park.pdf
EXTERNAL
There are no public comments posted to Item 7A. Please post this.
Thanks,
Nikki Kolhoff
----- Forwarded Message -----
From: Nikki Kolhoff <[email protected]>
To: [email protected] <[email protected]>; City Clerk <[email protected]> Sent: Tuesday, September 22, 2026 at 12:20:22 PM PDT
Subject: Fw: City Council 9/22/26 - Item 7A - CEQA Exemption is not Appropriate for Contaminated Business Park Development
Hello -
I sent this to all council members but inadvertently left off the meeting email. Please make sure this is in the public comment packet as it was sent before noon.
Thanks,
Nikki
----- Forwarded Message -----
From: Nikki Kolhoff <[email protected]>
To: Lana Negrete <[email protected]>; Caroline Torosis <[email protected]>; Jesse Zwick <[email protected]>; Natalya Zernitskaya <[email protected]>; Ellis Raskin <[email protected]>; Barry Snell <[email protected]>; Dan Hall <[email protected]> Cc: Oliver Chi <[email protected]>; Heidi Von Tongeln <[email protected]>; Jing Yeo <[email protected]>; Ross Fehrman <[email protected]>; Rachel Kwok <[email protected]>
Sent: Tuesday, September 22, 2026 at 11:42:16 AM PDT
Subject: City Council 9/22/26 - Item 7A - CEQA Exemption is not Appropriate for Contaminated Business Park Development
City Council -
Regarding the deteriorating state of Santa Monica's quest for water self-sufficiency, it's worth reminding everyone that development further impedes this goal. While the state has exempted most new development from CEQA, the city can still require a CEQA review if there is a risk to public Item 7-A
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2 health and safety, which there is when we have insufficient water, risk of contamination, and harm to residents.
Specifically with regard to the Airport Business Park, which is the former site of aerospace and missile manufacturing, it must be acknowledged that the land is contaminated and failure to remediate further jeopardizes our groundwater and ability to achieve water independence. Given the serious nature of the identified health hazards that would take it out of any claimed CEQA exemption, discussion among two government agencies is no substitute for CEQA's public review and comment process and City Council hearing. Ministerial approval of residential projects is not warranted, and conversely requiring us to accept residential development on contaminated land exposes the fallacy of these state laws pushed by the YIMBY/Abundance lobby.
The following are attached as evidence of contamination at the Business Park and the need for environmental investigation and remediation.
1. March 19, 2026 - Friends of Sunset Park wrote a detailed letter to the Regional Water Quality Board and the CITY PLANNING DEPARTMENT on March 19, 2026, analyzing the issues of contamination of the former Boeing properties now being proposed for residential housing, asking that CEQA be applied for full review of theses issues.
2. April 7, 2026 Letter from City Staff to Regional Water Quality Control Board - "The City respectfully requests that these issues be addressed before approval of redevelopment-related SMP implementation so that soil management activities are carried out in a manner that is consistent, transparent, and protective of human health, groundwater resources, and nearby sensitive receptors."
3. June 24, 2026 - Letter from Regional Water Quality Control Board - The RWQB responded to all points raised by FOSP, and agreed with many of its comments regarding contamination and remediation, but as to CEQA, stated: "The City of Santa Monica is the Lead Agency for the CEQA related to the proposed redevelopment projects at 2716 Ocean Park Boulevard and 2800 28th Street. The Los Angeles Water Board was not involved in any city-sponsored public outreach programs presented by developers as referenced in the Letter."
4. August 11, 2026 Anonymous 311 Response - FOSP submitted a question to Jing Yeo regarding the prior correspondence asking when the City would initiate an environmental review. Instead of responding directly, Jing created a 311 request and an anonymous response was generated stating, "Please note that the two referenced housing projects are Administrative Approvals and are therefore ministerial actions not subject to CEQA. The RWQCB and/or other regional agencies have jurisdictional oversight over any required cleanup and remediation of the site, if deemed necessary.
The City does require that prior to issuance of certificate of occupancy for the project sites, the sites have received a determination from the Regional Water Quality Control Board or other appropriate oversight agency that the site is suitable for residential or residential mixed use." In other words, the City plans to do nothing and let the development proceed with no environmental review of known contamination.
Please instruct staff to take the following actions immediately:
1. Seek an exception from the CEQA exemptions based on risk to health and safety;
2. Halt the processing of all development applications in the Airport Business Park; Item 7-A
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3 3. Commence an environmental analysis of the hazards identified, and the recommendations issued, with appropriate mitigation measures to be adopted under CEQA.
Surely the production of housing units is not the only metric by which we evaluate "progress". It is dangerous, irresponsible, and puts our water supply, health and safety at risk to exempt known contamination from the CEQA process. It is your duty to protect the health and safety of Santa Monica residents and ensure future access to clean water. This requires you to seek an exception to the CEQA exemptions for development in the known contaminated site of the Airport Business Park, and conduct a full environmental review and require full remediation and mitigation of all identified harms.
Regards,
Nikki Kolhoff
Sunset Park Resident
City Clerk: Please include this email and all four attachments in the public comment packet.
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Caution: External Email. Use caution when clicking links or opening attachments. When in doubt, contact DIT or use the Phish Alert Button.
To: WB-DIT-info4 <[email protected]>
Subject: Letter from FOSP board (Santa Monica neighborhood organization) March 19, 2026
Board Members and Executive Officer
Los Angeles Regional Water Quality Control Board
320 W. 4th Street, Suite 200
Los Angeles, CA 90013
Re: Public Comment for March 26, 2026 RWQB Meeting
And Re: City review of Residential Developments in Santa Monica Business Park Dear Regional Water Quality Board:
The Board of Directors of Friends of Sunset Park (FOSP), a nonprofit neighborhood community representing residents living adjacent to, and directly affected by, activities at and around Santa Monica Airport and the Santa Monica Business Park, submits this letter to expand on concerns previously raised in our February 7, 2024, correspondence to the Regional Water Quality Control Board, given that there are now pending applications for large residential developments on the Business Park parcels.
Friends of Sunset Park submits these comments based on information gleaned from the 2023 Historic Use Analysis of the Business Park, as well as the 2025 "Public Participation Plan" for the Boeing Former Douglas Aircraft Company Plant A Site, prepared for The Boeing Company, as well as the city-sponsored public outreach programs presented by developers concerning proposed development of two side-byside 8-story multi-unit residential buildings at 2716 Ocean Park Boulevard and 2800 28th Street. These disjointed and highly technical information programs are not a proper substitute for CEQA review, which is designed and intended to allow far more rigorous public comment and participation, through the formal legal processes established by statute. Nor does anything in the reports justify avoidance of a full remediation requirement of the subject properties. Because it appears that things are proceeding apace under the public radar, this is causing concern for our members.
Our organization is concerned that the developers’ public outreach and the “Public Participation Plan,” as circulated, are materially inadequate because they do not clearly explain to our residents, or the decision-makers, or prospective occupants, the continuing health and safety significance of unresolved volatile organic compound (“VOC”) contamination underlying portions of the former Douglas Aircraft Company Plant A area, including the portions extending westward toward 25th Street and the parcels now under consideration for high-density residential development at 2716 Ocean Park Boulevard and 2800 28th Street.
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Failure to Explain Specific Residential Health Risks
The technical materials referenced in the underlying site reports identify continuing unresolved contamination concerns in Subareas C, D, E, and F, including:
persistent high VOC concentrations in field gas zones underlying former source areas despite more than a decade of soil vapor extraction;
documented historical presence of Trichloroethylene and 1,1-Dichloroethylene in soil vapor and perched groundwater to depths approaching 90 feet below ground surface; downgradient detections indicating possible continuing plume migration; acknowledged need for further lateral and vertical delineation, including westward migration concerns toward Clover Park and adjacent residential areas.
Yet the Public Participation Plan does not explain in plain language that these contaminants present potential vapor intrusion risks to future residents, particularly:
children,
pregnant women,
elderly occupants, and
persons subject to long-duration indoor exposure.
A public participation document that omits a clear explanation of possible vapor intrusion pathways, sub-slab migration, and indoor-air exposure, cannot reasonably be considered effective public notice.
We are specifically concerned about proposals for residential development at 2716 Ocean Park Blvd and 2800 28th Street, and any other proposals in Subareas C, D, E, and F, in light of the documented presence of volatile organic compounds (VOCs) in soil vapor, perched groundwater, and the regional aquifer beneath and downgradient of these areas. The 2023 “Historical Use Analysis Report” by Advisian for the Santa Monica Airport area, as far as we can tell, identifies numerous problems to be addressed, listed at pp 94-95, including but not limited to:
Persistent, elevated VOC concentrations in fine‑grained zones beneath the former DAC Plant A area that have not significantly decreased after many years of soil vapor extraction, indicating a long‑term subsurface VOC reservoir.
Historical detections of trichloroethylene (TCE) and 1,1‑dichloroethene (1,1‑DCE) in soil vapor and perched groundwater in the vadose zone (to depths of approximately 90 feet) along the western portion of the site, and a clear recommendation for additional lateral and vertical delineation, including within and beneath Clover Park.
Consistent detections of 1,1‑DCE at monitoring well MW‑8 in the regional aquifer downgradient of the site since 2019, suggesting an actively migrating VOC plume whose full extent and behavior are not yet fully understood.
An explicit warning that before Airport #1 WSW or any proposed water‑supply wells in Item 7-A
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the area are brought into production, potential changes to the groundwater flow regime and effects on contaminant concentrations must be evaluated, along with further vadose‑zone characterization to understand VOC migration to the regional aquifer.
These findings underscore that the subsurface conditions remain incompletely characterized and that significant contamination persists in both the vadose zone and groundwater. While such conditions are already a cause for concern for commercial and industrial uses, they are fundamentally incompatible with high‑density residential development—especially when that development would house children, pregnant women, and other sensitive populations.
REMEDIATION IS WARRANTED
Per City of Santa Monica Planning Ordinance, a Phase 2 ESA site investigation is required for the entire Business Park properties prior to construction of multi-family residential housing. The field efforts should include soil vapor, soil, and groundwater sampling and chemical analysis for PCOC to protect public health and safety. BXP and Watt will be required to determine the extent of the contamination on their parcels. Here is the City of Santa Monica regulation, Section 9.31.195 F.:
Phase 1 Environmental Site Assessment. Multiple-unit dwelling projects in nonresidential districts or on a site identified on a list of hazardous materials sites compiled pursuant to Government Code Section 65962.5 shall conduct a Phase 1 Environmental Site Assessment to investigate for the presence of hazardous materials and/or waste contamination. If the Phase 1 ESA finds that contaminated soil or groundwater is suspected to be present, the Applicant shall perform soil sampling and analysis to determine the extent of contamination. If contaminants are detected in soil at or above regulatory levels, then the results of the soil sampling shall be reviewed and acted upon by the appropriate regional, state, or local regulatory agencies as needed. If remediation is necessary, a No Further Action letter or similar documentation indicating case closure shall be obtained under the appropriate oversight agency prior to project occupancy. (emph. added) From a community‑health perspective, residential uses pose a very different risk profile than historical or ongoing commercial uses:
Residents, including infants and children, can be present in their homes 20–24 hours per day, year‑round, over many years or decades, resulting in far higher cumulative exposure from any vapor intrusion than the typical adult worker in a commercial building.
Children have higher breathing rates per unit body weight and developing organs and nervous systems, making them more vulnerable to the toxic effects of chlorinated VOCs such as TCE and 1,1‑DCE; pregnant residents may face additional risks related to fetal development.
Bedrooms, nurseries, and play areas in residential buildings are often located on the ground floor or directly over slabs, increasing the likelihood that any vapor intrusion will affect spaces where children spend sustained periods and where they sleep.
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For these reasons, cleanup strategies, closure criteria, and engineering controls that might be regarded as acceptable for commercial/industrial land use are not adequate for long‑term residential occupancy. The underlying contaminant mass and plume stability must be addressed to a level that provides a substantial margin of safety for the most vulnerable residents, not just for adult workers.
The March 9, 2026, “Limited ESA Phase II Report,” states (page 3) that the BXP 2800 28th St site’s subsurface soil vapor is impacted at concentrations that present a “potential vapor intrusion risk,” i.e., above regulatory thresholds. This is substantial evidence documenting a need for a fulsome assessment of the clear risk to public health and safety at the site:
Investigation activities conducted at the Site have also identified deeper soil and groundwater impacts, which are being addressed by Boeing under oversight by the LARWQCB, Case # 0130B. This Work Plan does not include further assessment of the Site’s deeper impacted soil and groundwater, as BXP’s redevelopment planning does not require the collection of additional deeper data. The redevelopment of the Site will encompass the entire parcel; therefore, there will be no direct exposure to future Site occupants following the construction of the building. Similarly, the Site’s planned excavation will not extend to groundwater, which has been measured to be first encountered as perched groundwater at approximately 70 feet bgs. This Work Plan excludes the collection of additional soil vapor data, as it is already established that the Site’s subsurface soil vapor is impacted at concentrations that present a potential vapor intrusion risk.Given this concern, BXP will be installing a VIMS when constructing the Site’s new building, and further soil vapor data is not required to design the VIMS.
This report seems to imply that “all will be taken care of” by installation of a VIMS. However, installing a VIMS is not sufficient to protect occupants of a residential building; a VIMS is insufficient to mitigate risk to sensitive residential occupants, as this Guidance from the San Francisco RWQB indicates:
“Relationship Between VIM and Remediation
In general, the Regional Water Board considers VIM as an interim measure that is not a substitute for remediation of VFCs in the subsurface. In most cases, for new construction where a VIMS is needed to protect building occupants, we will not approve the VIMS until remediation to the extent feasible has been implemented. This could affect the local agency’s permitting decision for occupancy. Cleanup is the best way to reduce the magnitude of VI exposure that could occur if problems arise with VIMS, and it is the best way to reduce the timeframe over which VIMS are needed.
Nonetheless, VIMS are often necessary since achieving cleanup standards may take years given currently available remedial technologies. Additionally, VIM may be the only viable longterm response action where remediation is infeasible (e.g., further concentration reductions are not possible and residual concentrations pose a VI threat).(S.F. RWQB Vapor Intrusion Mitigation Guidance, p.3; emph. added)
CEQA REVIEW IS WARRANTED
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The City seems to believe these projects are subject only to ministerial approval, hence exempt from CEQA review. It may also be laboring under the assumption that impacts on future residents are not subject to CEQA. Although California law generally distinguishes between existing hazards affecting future residents and project-caused environmental effects, the controlling language of the California Supreme Court in California Building Industry Association v. Bay Area Air Quality Management District (2015) 62 Cal.4th 369, expressly preserves CEQA review where development may disturb or exacerbate existing contamination. The Supreme Court stated succinctly:
In light of CEQA‘s text, statutory structure, and purpose, we conclude that agencies subject to CEQA generally are not required to analyze the impact of existing environmental conditions on a project‘s future users or residents. But when a proposed project risks exacerbating those environmental hazards or conditions that already exist, an agency must analyze the potential impact of such
hazards on future residents or users. In those specific instances, it is the project’s
impact on the environment — and not the environment’s impact on the project —
that compels an evaluation of how future residents or users could be affected by exacerbated conditions.
(Id., second paragraph of opinion).
The Court further explained that redevelopment of a former industrial site requires CEQA review where contaminated soil may be disturbed or contamination may migrate.
That principle is directly implicated here because current technical findings acknowledge:
·unresolved VOC reservoirs,
·incomplete delineation,
·possible downgradient migration, and
·uncertainty regarding groundwater flow changes associated with future well production.
We believe that the evidence already in the files is sufficient for the City to find that the public health and safety issue requires CEQA analysis consistent with state law application of that particular assessment for the projects at hand.
Friends of Sunset Park does not agree that a residential building can be approved with this known risk without full review and full remediation, even if it does take years; therefore our Board respectfully requests and recommends the following:
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1. Full, Health‑Protective Remediation Before Any Residential Approvals The RWQB and City of Santa Monica should not approve any discretionary entitlements, rezonings, or permits that enable residential development in Subareas C, D, E, and F until the Regional Water Quality Control Board has determined that all relevant media—soil, soil vapor, perched groundwater, and the regional aquifer—have been fully investigated and remediated to standards appropriate for unrestricted residential use, including protection of children and pregnant residents.
Remediation must specifically address the persistent VOC reservoirs in the fine‑grained zones beneath the former DAC Plant A and any other identified source areas, with clear, measurable performance objectives based on actual reductions in VOC mass and concentrations, not simply operating time for remediation systems.
2. Completion of Subsurface Characterization and Plume Delineation The additional lateral and vertical delineation of soil vapor and perched groundwater recommended in the 2023 investigations—particularly to the west and into Clover Park—should be completed and made publicly available before any residential entitlements are considered.
The VOC plume in the regional aquifer, including but not limited to 1,1‑DCE detections at MW‑8 and any other downgradient wells, should be fully delineated and modeled, demonstrating that the plume is under control and trending toward cleanup rather than expansion.
3. Integrated Evaluation of Groundwater Pumping and Land‑Use Change Any decision to activate or modify Airport #1 WSW or other water‑supply wells in the area must be evaluated together with proposed land‑use changes, including residential redevelopment, recognizing that groundwater pumping can alter plume behavior and vapor‑intrusion potentials beneath existing and future buildings.
A combined analysis should be required, examining how different pumping scenarios may affect VOC concentrations at supply wells and within underlying soils and vapors beneath current and proposed residential areas.
4. Residential and Child‑Focused Health‑Risk Standards
Cleanup and closure decisions must be based on exposure assumptions and target Item 7-A
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levels appropriate for 24‑hour‑per‑day, long‑term residential occupancy, including infants, children, and pregnant residents—not on less protective commercial/industrial worker scenarios.
A quantitative health‑risk assessment should be required that explicitly evaluates chronic and subchronic indoor‑air exposure to TCE, 1,1‑DCE, and related VOCs for sensitive populations, as well as potential drinking‑water exposure if groundwater is or may be used.
5. Enforceable Long‑Term Protections and Monitoring
If, even after aggressive remediation, residual contamination remains that could contribute to vapor intrusion, residential development should only proceed with enforceable engineering controls (e.g., sub‑slab depressurization, vapor barriers) and robust long‑term monitoring programs that are clearly funded, maintained, and periodically reviewed for the life of the buildings.
Institutional controls, including land‑use covenants, requirements for periodic re‑evaluation of site conditions, and disclosure requirements for future occupants, should be mandatory components of any approval for residential use on or near affected areas.
6. Transparent, Coordinated Oversight and Public Process The City should conduct a full, project‑specific environmental review, consistent with CEQA, that incorporates the most current data and requirements from the Regional Board, and that directly addresses whether site conditions are safe for residential development with child‑sensitive receptors.
The Regional Board should clearly state whether the remedial approach and any prospective closure determinations are intended to support unrestricted residential use and, if so, the technical basis and conditions (including monitoring and contingency measures) for that conclusion.
Our February 7, 2024, letter to the Regional Board raised our concerns only from the perspective of clean-up costs impacting affected neighborhood association as taxpayers. This (new) joint communication to both the City and the Regional Board is intended to make clear that Friends of Sunset Park strongly opposes moving forward with residential development in Subareas C, D, E, and F until the subsurface conditions are thoroughly characterized, aggressively remediated by the property antecedent owners/users , and demonstrated to be protective of long‑term residential use, particularly for children.
We respectfully request that this letter be placed in the administrative record for all land‑use, CEQA, and cleanup decisions affecting the Santa Monica Business Park and surrounding Item 7-A
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areas, with specific reference to residential projects being proposed at 2716 Ocean Park Blvd. and 2800 28th Street and groundwater supply for Santa Monica, and, since we are not the experts in this field, that both agencies provide written responses for public consumption addressing how the issues raised here and in our February 7, 2024, letter will be resolved prior to any project approval for residential development. We are well aware of the claims being made by certain housing advocates that an affordable housing crisis demands more units be built without environmental review of any kind. The idea that environmental review should be skipped is based on the false premises that environmental review is just red tape with no benefit, that thwarts development, or that our vulnerable populations can be relegated to living on contaminated land. We disagree. Everyone is entitled to live on clean and safe land, and expedience can never be justification for avoiding proper study and remediation when contamination is know to exist at the site of a former airplane and munitions manufacturer.
Furthermore, this is a market-rate housing development, and building more luxury units in Santa Monica without the proper level of environmental review will not solve the purported “affordability” crisis in any way, and clearly endangers the health of the children and others who will occupy those buildings without knowing the dangers lurking in the vapors they will be breathing.
Thank you for your attention and anticipated response.
Sincerely,
Board of Directors
Friends of Sunset Park
By:
Clare Thomas
President, Friends of Sunset Park
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2500 Michigan Ave., Building 1, Santa Monica, 90404 • (310) 458-8235 • [email protected] santamonica.gov • @cityofsantamonica • @santamonicacity Public Works Department
Water Resources Division
April 7, 2026
Ana Townsend
Water Resource Control Engineer
Los Angeles Regional Water Quality Control Board
320 W. 4th Street, Suite 200
Los Angeles, CA 90013
RE: Comments and Technical Review of the Soil Management Plan (December 18, 2025), Former Douglas Aircraft Company Plant A, Santa Monica, California
Dear Ms. Townsend,
On behalf of the City of Santa Monica (the City), I am transmitting the enclosed technical memorandum, Technical Review of the Soil Management Plan Prepared for the Former Douglas Aircraft Company Plant A, Santa Monica, California, dated March 18, 2026, prepared by Hazen and Sawyer for the City.
The memorandum presents the City’s technical review of the Soil Management Plan (SMP) prepared by Engineering Analytics, Inc. on behalf of The Boeing Company and dated December 18, 2025. As reflected in the enclosed memorandum, the City recognizes that the SMP includes a generally sound framework and several useful procedural elements. However, given the size and complexity of the approximately 112-acre site, its multi-parcel configuration, phased redevelopment context, contamination history, and the presence of sensitive receptors including schools and daycare facilities, the City believes the SMP requires further revision before it can be considered sufficiently specific and implementable for sitewide redevelopment activities. The City recognizes that the Los Angeles Regional Water Quality Control Board has taken an adaptive approach in which the plan and remediation efforts may be refined over time. However, with housing developments already being proposed over the site—and additional projects anticipated in the near future—it is essential that a more thorough and comprehensive plan be established as soon as possible.In particular, the City requests that the Los Angeles Regional Water Quality Control Board direct Boeing to revise and resubmit the SMP to address the following key recommendations identified in the technical memorandum:
• Develop a parcel-specific SMP implementation matrix and parcel maps for each Assessor’s Identification Number (AIN), including land use, contaminants of potential concern, impact zones, screening levels, monitoring requirements, stop-work triggers, and responsible parties. • Require pre-characterization and delineated contaminant management zones based on site history, prior investigation data, and contaminant-specific behavior, rather than relying primarily on reactive field observations during construction.
• Incorporate a clearly defined stop-work and restart decision framework, including numeric triggers, defined authority, notification pathways, restart criteria, and minimum professional qualifications for oversight personnel.
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2500 Michigan Ave., Building 1, Santa Monica, 90404 • (310) 458-8235 • [email protected] santamonica.gov • @cityofsantamonica • @santamonicacity • Add a groundwater protection measure for residual contamination at the base of excavations, including confirmation sampling, leaching-to-groundwater evaluation criteria, and notification and approval requirements before backfilling.
• Establish a sensitive receptor protection protocol for areas adjacent to or occupied by schools and daycare facilities, including enhanced dust and air monitoring, operational restrictions, and advance communication procedures.
• Define a clear screening level and risk decision framework, including receptor assumptions, acceptable risk thresholds, cumulative risk methodology, post-remediation human health risk assessment requirements, and clarification that No Further Action determinations are made by the Los Angeles Regional Water Quality Control Board (LARWQCB). • Strengthen stockpile management and soil movement controls, including segregation, tracking, cross-parcel transfer restrictions, and documented approval pathways for reuse or disposal decisions.
• Integrate stormwater management into the soil disturbance framework, with defined best management practices (BMPs), contact water procedures, parcel-level responsibilities, and discharge authorization requirements.
• Include additional process-related contaminants of potential concern where warranted, specifically per- and polyfluoroalkyl substances (PFAS), hexavalent chromium, and 1,4-dioxane, in areas associated with historical plating, surface finishing, degreasing, solvent handling, or wastewater management.
• Address the Phase I Environmental Site Assessment (Phase I ESA) recommendations for 2800 28th Street (AIN 4272-031-005) by requiring parcel-specific pre-characterization and an SMP framework that incorporates those findings before redevelopment proceeds.
The City respectfully requests that these issues be addressed before approval of redevelopment-related SMP implementation so that soil management activities are carried out in a manner that is consistent, transparent, and protective of human health, groundwater resources, and nearby sensitive receptors.
Thank you for your consideration of the City’s comments. Please contact me if you have any questions regarding this transmittal.
Sincerely,
Sunny Wang, P.E.
Water Resources Manager
City of Santa Monica
Enclosure: Technical Memorandum, Technical Review of the Soil Management Plan Prepared for the Former Douglas Aircraft Company Plant A, Santa Monica, California Item 7-A
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Hazen and Sawyer • 800 W. 6th Street, Suite 1400 • Los Angeles, CA 90017 • 213.234.1080 Technical Memorandum
Job no: 20302-000
March 19, 2026
To: Christopher Dishlip, PE (City of Santa Monica)
From: Stephanie Bustos, PG (Hazen and Sawyer)
Mark Trudell, PhD, PG, CHG (Hazen and Sawyer)
cc: Sunny Wang, PE (City of Santa Monica)
Lisette A. Gold, D. Env (City of Santa Monica)
Susan Cola (City of Santa Monica)
Brandon Ward (City of Santa Monica)
Monica Tejeda (City of Santa Monica)
Shannon Parry (City of Santa Monica)
Subject: Technical Review of the Soil Management Plan Prepared for the Former Douglas Aircraft Company Plant A, Santa Monica, California Synopsis
Hazen and Sawyer conducted a technical review of the Soil Management Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California (the Site), prepared by Engineering Analytics, Inc. for The Boeing Company (December 18, 2025). The review evaluated whether the Soil Management Plan (SMP) provides sufficient specificity and governance to ensure consistent and protective implementation during phased redevelopment of the approximately 112-acre Site, which includes multiple parcels, varied land uses, and sensitive receptors including schools and daycare facilities.
Overall, the SMP provides a sound structural framework and includes several strong procedural elements.
However, given the size and complexity of the Site, additional implementation detail and oversight controls are needed to ensure consistent application across parcels and contractors. This memorandum identifies targeted improvements related to parcel-level implementation, contaminant management zoning, stop-work authority, groundwater protection where residual contamination remains at the base of excavations, sensitive receptor protection, risk decision-making, soil movement controls, and stormwater integration. The review also identifies additional contaminants reasonably associated with historical operations that warrant consideration during soil disturbance activities and evaluates alignment with Phase I Environmental Site Assessment (Phase I ESA) recommendations for 2800 28th Street (AIN 4272- 031-005).
The recommended improvements are intended to strengthen the SMP's implementability while preserving its overall structure and supporting protective redevelopment under LARWQCB oversight. This is especially critical given that housing developments are already being proposed across the Site and additional redevelopment projects are anticipated in the near term, making it essential that a more thorough and comprehensive plan be established as soon as possible.
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Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page ii The undersigned licensed professionals conducted an independent technical review of the Soil Management Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California, prepared by Engineering Analytics, Inc. for The Boeing Company (December 18, 2025). The findings, conclusions, and recommendations presented in this report reflect their professional judgment and are submitted under their respective professional certifications.
Exp. 06/23/2026
Stephanie Bustos, PG
Senior Associate
Exp. 01/31/2028
Mark Trudell, PhD, PG, CHG
Senior Associate
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Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page iii Table of Contents
1. Introduction............................................................................................................... 1
1.1 Purpose.......................................................................................................................................1
1.2 Summary of SMP Strengths and Areas Requiring Revision ......................................................2
2. Governance and Implementation Framework Improvements ................................... 3
2.1 Recommended Improvement 1: Parcel-Specific SMP Implementation Matrix (AIN-by-AIN) and Parcel Maps ................................................................................................................................3
2.1.1 Issue ..............................................................................................................................4
2.1.2 Recommendation...........................................................................................................4
2.1.3 Rationale........................................................................................................................4
2.2 Recommended Improvement 2: Pre-Characterization and Delineated Contaminant Management Zones ....................................................................................................................5
2.2.1 Issue ..............................................................................................................................5
2.2.2 Recommendation...........................................................................................................5
2.2.2.1 Implementation Controls ................................................................................6
2.2.2.2 Governance Controls .....................................................................................6
2.2.3 Rationale........................................................................................................................6
2.3 Recommended Improvement 3: Stop-Work and Restart Decision Framework with Defined Authority......................................................................................................................................6
2.3.1 Issue ..............................................................................................................................7
2.3.2 Recommendation...........................................................................................................7
2.3.2.1 Defined Stop-Work Triggers...........................................................................7
2.3.2.2 Immediate Response Controls (Implementation Measures)..........................8
2.3.2.3 Defined Authority and Escalation (Governance Measures)...........................8
2.3.2.4 Restart Criteria ...............................................................................................9
2.3.3 Rationale........................................................................................................................9
2.3.4 Professional Qualifications and Oversight...................................................................10
2.3.5 Supplemental Groundwater Protection Measure: Residual Contamination at the Base of Excavations..............................................................................................................10
2.3.5.1 Issue.............................................................................................................10
2.3.5.2 Recommendation .........................................................................................11
2.3.5.3 Rationale ......................................................................................................11 Item 7-A
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2.4 Recommended Improvement 4: Sensitive Receptor Protection Protocol ................................11
2.4.1 Issue ............................................................................................................................12
2.4.2 Recommendation.........................................................................................................12
2.4.2.1 Enhanced Implementation Controls .............................................................12
2.4.2.2 Operational Restrictions...............................................................................13
2.4.2.3 Governance and Communication Measures................................................13
2.4.3 Rationale......................................................................................................................13
2.5 Recommended Improvement 5: Clear Screening Level (SL) and Risk Framework.................13
2.5.1 Issue ............................................................................................................................14
2.5.2 Recommendation.........................................................................................................14
2.5.2.1 Defined Risk Criteria (Governance Elements).............................................14
2.5.2.2 Implementation Requirements .....................................................................15
2.5.3 Rationale......................................................................................................................15
2.5.4 Regulatory Authority for No Further Action Determinations ........................................15
2.5.5 Post-Remediation Human Health Risk Assessment Requirements ............................16
2.6 Recommended Improvement 6: Stockpile Management and Soil Movement Controls ...........16
2.6.1 Issue ............................................................................................................................16
2.6.2 Recommendation.........................................................................................................17
2.6.2.1 Implementation Controls ..............................................................................17
2.6.2.2 Governance Controls ...................................................................................17
2.6.3 Rationale......................................................................................................................18
2.7 Recommended Improvement 7: Stormwater Integration..........................................................18
2.7.1 Issue ............................................................................................................................18
2.7.2 Recommendation.........................................................................................................19
2.7.2.1 Implementation Controls ..............................................................................19
2.7.2.2 Governance Controls ...................................................................................19
2.7.3 Rationale......................................................................................................................20
3. Additional Considerations: Process-Related Contaminants of Potential Concern .. 21
3.1 Per- and Polyfluoroalkyl Substances (PFAS) and Hexavalent Chromium (Cr(VI)) ..................21
3.2 Consideration of 1,4-Dioxane as a Contaminant of Potential Concern ....................................22
4. Evaluation of Phase I ESA Recommendations and SMP Alignment ...................... 24 Item 7-A
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4.1 Phase I ESA Recommendation 1: Soil Pre-Characterization...................................................24
4.2 Phase I ESA Recommendation 2: Preparation of an SMP Using Pre-Characterization Data .25
5. Conclusions ............................................................................................................ 27
5.1 Recommended Governance and Implementation Revisions ...................................................27
5.2 Additional Contaminant Considerations....................................................................................29
5.3 Phase I ESA Alignment Determinations for 2800 28th Street (AIN 4272-031-005) .................29
6. References ............................................................................................................. 31 Item 7-A
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1. Introduction
Hazen and Sawyer (Hazen) conducted a technical review of the Soil Management Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California (the Site), prepared by Engineering Analytics, Inc. (EA) on behalf of The Boeing Company (Boeing), dated December 18, 2025. This document is referred to herein as the SMP.
The Site encompasses approximately 112 acres and includes multiple Assessor's Identification Numbers (AINs) across parcels owned by Watt Headquarters Limited Partnership, SMBP LLC, SC Enterprises SMBP LLC, and the City of Santa Monica. Current land uses include the Santa Monica Business Park (SMBP), Clover Park, and a residential neighborhood in the northeastern portion of the property. The Site encompasses varied land uses, multiple ownership structures, phased redevelopment activities, and a complex environmental history involving volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), metals, petroleum hydrocarbons, and other chemicals of potential concern (COPCs).
Environmental assessment and soil vapor extraction (SVE) are ongoing at the Site under the direction of the Los Angeles Regional Water Quality Control Board (LARWQCB), which retains regulatory oversight authority for investigation and remediation activities at the Site.
The Site was decommissioned and demolished between 1975 and the late 1970s, before modern federal and state regulatory programs for investigation and remediation of subsurface contamination were established. Consequently, decommissioning activities were not conducted in accordance with current risk-based standards and did not include comprehensive subsurface characterization consistent with modern regulatory frameworks. It is therefore not unexpected that residual soil, soil gas, and groundwater impacts remain at the Site despite subsequent VOC reduction efforts, including operation of SVE systems in select areas.
1.1 Purpose
The purpose of this technical review is to assess whether the SMP, as written, is sufficiently prescriptive and implementable to ensure consistent and defensible protection of human health and the environment during phased redevelopment across a large, multi-parcel site. This review focuses on:
• Protectiveness and implementability: Whether the SMP contains adequate governance structure, decision logic, contaminant-specific controls, documentation processes, and implementation standards appropriate for a 112-acre, multi-contractor, phased redevelopment site with sensitive receptors.
• Phase I Environmental Site Assessment alignment for 2800 28th Street (AIN 4272-031-005):
Whether the SMP adequately addresses the recommendations of the Phase I Environmental Site Assessment (Phase I ESA; Haley & Aldrich, Inc., 2025), including pre-characterization of soil and development of the SMP based on characterization results and Boeing data.
Section 2 identifies minimum governance and implementation improvements needed for the SMP to function consistently across a multi-parcel, multi-contractor redevelopment site. Section 3 identifies Item 7-A
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1.2 Summary of SMP Strengths and Areas Requiring Revision The current SMP framework is structurally sound and generally aligned with LARWQCB oversight requirements for construction-phase soil disturbance at a large redevelopment site, and it appropriately incorporates compliance-related elements where applicable under South Coast Air Quality Management District (SCAQMD) requirements. The SMP also includes a number of strong procedural elements:
• Clear notification procedures to the LARWQCB, including defined advance notification timing and responsible party identification.
• Defined field monitoring protocols addressing SCAQMD Rule 1166 and Rule 1466 compliance where applicable, including parcel-specific monitoring areas. • Procedures for soil impact assessment, step-out sampling, confirmation sampling, and excavation management.
• Soil stockpile management and waste characterization and disposal procedures. • Imported fill material screening procedures consistent with the California Department of Toxic Substances Control (DTSC) Information Advisory on Clean Imported Fill (DTSC, 2001). • Parcel-specific reporting requirements submitted to the LARWQCB upon completion of soil management activities at each parcel.
However, due to the Site's size (approximately 112 acres), multi-parcel ownership structure, complex contamination history, and presence of sensitive receptors, including daycare facilities and a private elementary school within the Site boundaries, additional specificity and implementation controls, including clear authority, decision triggers, documentation standards, and parcel-specific execution procedures, are necessary to ensure the SMP is not merely workable in concept, but defensibly protective in implementation across all parcels, contractors, and redevelopment phases.
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2. Governance and Implementation Framework Improvements The primary concern is not the absence of regulatory citations or procedural components within the SMP.
Rather, it is the reliance on generalized implementation language such as "case-by-case application" (SMP Section 2.5), "professional judgment" (SMP Sections 5.1 and 6.5.1), and direction to "notify human health risk assessment (HHRA) team" (SMP Section 5.4), without clearly defined decision criteria, authority thresholds, documentation standards, or parcel-specific execution controls.
While such terminology may be workable at smaller or less complex sites, on a 112-acre, multicontractor, phased redevelopment site, discretionary language without structured decision logic and defined implementation controls introduces the potential for inconsistent field application across parcels, contractors, and construction phases.
DTSC guidance emphasizes that site management plans should establish clear decision logic, defined implementation triggers, and documentation pathways sufficient to ensure consistent protectiveness across varying land uses and site conditions (DTSC, 2011). United States Environmental Protection Agency (EPA) guidance on systematic planning likewise emphasizes predefined decision criteria and documentation pathways to support defensible environmental decision-making (EPA, 2006).
For a site of this scale and complexity, the SMP must function both as a governance framework that defines authority, triggers, escalation pathways, and documentation standards, and as an implementation framework that provides parcel-specific controls, monitoring requirements, defined stop-work and restart criteria, and consistent field execution standards.
Without integration of both governance structure and implementation clarity, protective measures may vary across parcels and project phases, potentially resulting in inconsistent exposure assumptions, uneven application of controls, and reduced regulatory defensibility. The following subsections present the governance and implementation improvements necessary to strengthen field execution, promote consistency across parcels and contractors, and ensure defensible protection of human health and the environment. These improvements are intended to clarify implementation and oversight, not to expand the SMP’s scope beyond construction-phase soil management. The traceability notes provided below identify the principal SMP sections where the current language is either too general, reactive, or incomplete for a site of this scale.
2.1 Recommended Improvement 1: Parcel-Specific SMP Implementation Matrix (AIN-by-AIN) and Parcel Maps
On a multi-parcel redevelopment site with varying land uses, ownership structures, and known areas of contamination, implementation consistency cannot rely solely on sitewide language. A parcel-specific governance and implementation framework is necessary to ensure that risk assumptions, monitoring requirements, and management controls are applied consistently and transparently across all AINs.
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2.1.1 Issue
The SMP applies sitewide but does not provide a parcel-specific governance and implementation structure. On a multi-owner, phased redevelopment site, absence of parcel-level controls may result in inconsistent field application between contractors and construction phases.
Traceability to SMP. This deficiency is traceable to the SMP’s sitewide applicability and ownership discussion in Section 2.1, its sitewide notification and implementation framework in Sections 3.1 through
4.4, and its parcel-specific reporting provision in Section 10.3. While the SMP recognizes parcel ownership and requires parcel-specific reporting, it does not establish parcel-specific implementation controls, parcel maps, or AIN-specific decision criteria before work begins.
2.1.2 Recommendation
Develop a Parcel-Specific SMP Implementation Matrix that functions as both a governance tool and an implementation guide for each AIN. The matrix should define:
• Current and planned land use.
• Presence of sensitive receptors.
• Known COPCs and impact zones.
• Default receptor assumptions and applicable screening levels. • Monitoring and perimeter requirements.
• Stop-work triggers and notification pathways.
• Documentation and approval standards.
• Responsible parties (owner/operator/contractor roles) and designated points of contact.
Parcel maps should visually delineate AIN boundaries, impact zones, sensitive receptor interfaces, and monitoring applicability areas.
2.1.3 Rationale
EPA guidance for large, complex sites emphasizes structured management systems and alignment between land use assumptions, exposure scenarios, and site controls (EPA, 2006). DTSC similarly requires that site management measures be consistent with anticipated land use and exposure conditions (DTSC, 2011). A parcel-specific matrix implements this alignment and promotes consistent field execution.
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2.2 Recommended Improvement 2: Pre-Characterization and Delineated Contaminant Management Zones
Effective soil management requires that site history and contaminant-specific behavior be considered before excavation or other soil-disturbing activities begin. For non-volatile contaminants such as polychlorinated biphenyls (PCBs) and metals, field screening tools commonly used for VOCs, such as photoionization detector (PID) monitoring, are not reliable indicators of the presence or extent of contamination, and impacts may not be visually apparent. Accordingly, pre-characterization and advance delineation of contaminant management zones are necessary to support proactive sampling, consistent implementation of excavation, handling, and worker protection measures appropriate to the contaminants present, and defensible decision-making.
2.2.1 Issue
The SMP relies primarily on visual observations, odors, and PID readings to identify potential impacts during soil disturbance. While these tools may be appropriate for VOCs and petroleum hydrocarbons, they are not suitable for detecting non-volatile contaminants such as PCBs, metals, and certain semivolatile compounds. In the absence of predefined contaminant management zones, reliance on field discretion may result in under-identification of impacts and inconsistent implementation across parcels and contractors.
Traceability to SMP. This deficiency is traceable to Sections 4.1 through 4.3, Section 5.1, Section 5.2, and Sections 6.1 through 6.5, which rely largely on observation, field screening, impact identification during work, step-out sampling, and confirmation sampling after disturbance. The SMP does not require predefined contaminant management zones based on known historical operations and existing investigation data before excavation proceeds.
2.2.2 Recommendation
The SMP should require the development and incorporation of Delineated Contaminant Management Zones that identify areas of known contamination and areas with a high likelihood of contamination based on historical operations, prior investigation data, investigation data being generated through implementation of the Additional Site Assessment Work Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California dated November 26, 2024, and the Additional Site Assessment Work Plan Addendum Number 1, Boeing Former Douglas Aircraft Company (DAC) Plant A, Santa Monica, California (collectively, the Work Plans), both prepared by EA, and contaminant-specific behavior. These zones should be mapped both laterally and vertically and should be clearly referenced to individual parcels.
For each zone, the SMP should define implementation and governance requirements, including, at a minimum, the elements described in Sections 2.2.2.1 and 2.2.2.2 below:
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2.2.2.1 Implementation Controls
• Mandatory pre-disturbance characterization sampling.
• Excavation and confirmation sampling protocols.
• Enhanced air quality, particulate, dust, field screening, and/or sampling requirements appropriate to zone-specific COPCs.
• Waste profiling triggers.
2.2.2.2 Governance Controls
• Defined decision thresholds for additional characterization, removal, or other response actions. • Documentation requirements prior to soil movement, reuse, or off-site disposal. • Defined approval authority for alternative management approaches.
Zone maps should be integrated with the Parcel-Specific Implementation Matrix to ensure alignment between mapped conditions, risk assumptions, and required controls.
2.2.3 Rationale
EPA’s Guidance on Systematic Planning Using the Data Quality Objectives Process emphasizes the need for structured, contaminant-specific planning prior to field implementation (EPA, 2006). DTSC guidance similarly indicates that characterization strategies should reflect contaminant properties and site history rather than rely solely on observational criteria (DTSC, 2011). Establishing delineated contaminant management zones prior to excavation promotes proactive control, reduces reliance on subjective field judgment, and enhances consistency and defensibility across redevelopment phases.
2.3 Recommended Improvement 3: Stop-Work and Restart Decision Framework with Defined Authority
On large, phased redevelopment sites involving multiple contractors and concurrent construction activities, clearly defined stop-work and restart procedures are essential to maintaining consistent environmental oversight. Ambiguity in authority, escalation pathways, or restart criteria may result in inconsistent field decisions, premature resumption of work, and reduced protectiveness. This concern is consistent with EPA guidance emphasizing structured planning and documented implementation responsibilities during contaminated site management and redevelopment, and with DTSC guidance recognizing the need for site-specific soil management procedures where contaminated soil may be encountered during cleanup and redevelopment activities (EPA, 2021; EPA, 2012; DTSC, 2011).
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2.3.1 Issue
The SMP states that work “should stop” if impacts are discovered; however, it does not clearly define stop-work authority, immediate response requirements, escalation thresholds, or restart criteria. On a multi-contractor redevelopment site, reliance on discretionary interpretation without defined restart conditions creates the potential for inconsistent implementation, uneven application of protective measures, and premature resumption of work.
EPA and DTSC guidance for contaminated site cleanup and redevelopment supports the use of clearly defined roles, decision-making procedures, and documented response actions to help maintain protective and consistent implementation during redevelopment activities. EPA redevelopment guidance describes a structured process for evaluating contaminated properties, documenting redevelopment decision-making, and identifying actions needed to support productive reuse, including management of environmental conditions and risk. EPA institutional controls guidance also emphasizes planning, implementation, maintenance, and enforcement responsibilities as part of long-term site management. DTSC guidance likewise recognizes that site-specific soil management procedures may be necessary to ensure contaminated soil is handled in a manner that prevents exposure during cleanup and redevelopment activities. Occupational and construction safety regulations likewise require defined procedures to protect workers when hazardous materials or other unsafe conditions may be encountered during excavation and related work, including Title 8, California Code of Regulations, Section 5192 (Hazardous Waste Operations and Emergency Response) and Section 1541 (General Requirements for Excavations) (EPA, 2021; EPA, 2012; DTSC, 2011).
2.3.2 Recommendation
Incorporate a clearly defined Stop-Work and Restart Decision Framework that establishes both governance and implementation controls. A one-page decision tree should be included within the SMP and referenced in contractor pre-construction meetings.
2.3.2.1 Defined Stop-Work Triggers
Work within the affected area must immediately stop upon occurrence of any of the following:
• PID readings exceeding a site-specific numeric action level above background conditions, as defined in the field screening plan, including instrument calibration and bump test requirements and the background determination method, and documented by the qualified environmental professional (QEP) of record. For purposes of this review, the QEP is the designated environmental professional responsible for SMP implementation and oversight, under the supervision of a California-licensed Professional Geologist (PG) and/or Professional Engineer (PE), as appropriate.
• Visible staining or discoloration of soil, or chemical odors detected in ambient air during soil disturbance.
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• Receipt of laboratory analytical results exceeding the applicable soil matrix screening level or cumulative risk threshold.
• Perimeter air monitoring exceedance under SCAQMD Rule 1166 or Rule 1466, where those rules are applicable to the activity being conducted.
Where feasible, all triggers should be expressed as numeric thresholds to minimize subjective field interpretation.
2.3.2.2 Immediate Response Controls (Implementation Measures) Upon stop-work, the following measures should be implemented without delay:
• Establish an exclusion zone around the affected area. • Secure and cover exposed soils and stockpiles.
• Implement dust suppression measures.
• Stabilize the excavation as necessary to prevent further exposure or migration. • Initiate the defined notification cascade, such as Environmental Observer to Site EH&S Manager to Property Owner to LARWQCB, as applicable.
• Collect confirmation samples and submit for expedited laboratory analysis to confirm or refute field observations prior to restart. Analytical turnaround requirements should be defined in advance and coordinated with the contract laboratory to minimize work stoppage duration while ensuring data defensibility.
Immediate response procedures should be standardized across all parcels and contractors to ensure consistent field execution.
2.3.2.3 Defined Authority and Escalation (Governance Measures) The SMP should explicitly identify the following authority designations:
• Environmental Observer authority to initiate stop-work at the parcel level. • Site EH&S Manager authority to suspend broader site operations if warranted. • Defined regulatory notification thresholds triggering LARWQCB contact. • Circumstances requiring LARWQCB concurrence prior to restart.
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2.3.2.4 Restart Criteria
Work in the affected area may not resume until all of the following conditions are satisfied:
• Impact delineation is completed, with lateral and vertical extent defined or bounded. • A control strategy is established, consisting of removal to applicable screening levels, a documented risk evaluation for residual concentrations, or incorporation of engineering controls, as appropriate to site conditions.
• Applicable field monitoring demonstrates conditions are below pre-established action levels for a defined minimum interval, as specified in the SMP and/or the activity-specific monitoring approach, as applicable.
• Regulatory notification is completed where required under applicable LARWQCB oversight requirements.
• Written restart authorization is issued by both the Environmental Observer and the Site EH&S Manager, with LARWQCB concurrence obtained where required. • All stop-work conditions, response actions, and restart determinations are documented in the daily field log and weekly report.
2.3.3 Rationale
On large redevelopment sites, ambiguity regarding stop-work initiation, escalation, and restart authority can lead to inconsistent application, contractor pressure to resume work, and increased potential for exposure or incomplete response actions. Clearly defined restart criteria are as important as stop-work triggers because they establish the basis for determining when conditions have been sufficiently evaluated and controlled to allow work to resume in a protective and documented manner.
A defined Stop-Work and Restart Decision Framework strengthens implementation consistency by assigning responsibility, standardizing response actions, and reducing reliance on individual judgment in the field. This approach is consistent with United States Environmental Protection Agency (EPA) guidance emphasizing documented planning, implementation responsibilities, and long-term protectiveness in contaminated site management, as well as DTSC guidance recognizing the importance of site-specific soil management procedures during cleanup and redevelopment activities (EPA, 2021; EPA, 2012; DTSC, 2011).
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2.3.4 Professional Qualifications and Oversight
The SMP should specify minimum professional qualifications for individuals responsible for implementing and supervising soil management activities. At a minimum, the qualified environmental professional of record should hold a current California Professional Geologist (PG) or Professional Engineer (PE) license, or work under the direct supervision of a licensed PG or PE, as appropriate to the scope of work. The SMP should clearly define field decision authority for stop-work initiation, sample selection, and excavation expansion decisions. Clear delineation of professional oversight responsibilities strengthens implementation consistency, accountability, and defensibility during SMP execution. This recommendation is consistent with the broader EPA and DTSC emphasis on documented implementation responsibilities and site-specific management procedures at contaminated sites (EPA, 2012; DTSC, 2011).
2.3.5 Supplemental Groundwater Protection Measure: Residual Contamination at the Base of Excavations
This section considers the need for a groundwater-protective approach when contaminated soil may remain at the base of excavations. The SMP currently focuses on shallow soil exposure but does not clearly address whether deeper residual contamination left in place could continue to affect groundwater.
Because groundwater beneath the Site is already impacted by contamination from historical site use and the groundwater aquifer is designated for drinking water use, this issue should be addressed explicitly in the SMP.
2.3.5.1 Issue
The SMP does not establish procedures for addressing contaminated soil that may remain at the base of excavations after final grade is reached. Section 2.5, Screening Levels, states that “12 feet would be the likely maximum depth of disturbance during potential future redevelopment and Site use and maintenance activities, and that 12 feet is therefore the maximum depth of soil to which future receptor populations could be directly exposed.” However, this framework considers only potential direct exposure to shallow soil and does not address the potential risk that deeper residual contamination may continue to pose to groundwater. Given that groundwater beneath the Site, and potentially downgradient of the Site, has already been affected by contamination, including trichloroethylene (TCE) at concentrations above the applicable maximum contaminant level (MCL) of 5 µg/L and tert-butyl alcohol (TBA) above the California notification level of 12 µg/L, and that the groundwater is designated for Municipal and Domestic Supply (MUN) beneficial use, residual soil contamination at depth may represent an ongoing source of contaminant loading to an already impaired groundwater resource.
Traceability to SMP. This deficiency is traceable to Section 2.5, Section 6.5, and Section 6.6. The SMP’s risk framework is tied to direct exposure assumptions for shallow soil, and its confirmation sampling and post-remediation HHRA provisions do not establish separate criteria for evaluating whether deeper residual soil left at the base of excavations may continue to affect groundwater.
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2.3.5.2 Recommendation
Boeing should be directed to revise the SMP to incorporate procedures for managing residual soil contamination remaining in place at the base of excavations. At a minimum, the revised SMP should define:
• Confirmation sampling requirements at the base of each excavation upon reaching planned final grade, including minimum sample density and spatial distribution criteria. • Leaching-to-groundwater evaluation criteria for residual soil concentrations remaining at depth, including applicable soil-to-groundwater screening values or leaching factors consistent with California regulatory practice.
• Concentration thresholds for base-of-excavation soils requiring LARWQCB notification prior to backfill, including the notification pathway and required supporting documentation; and • Documentation requirements for any residual-in-place determination, including the basis for determining that residual concentrations are acceptable relative to groundwater protection criteria, the identity of the QEP of record approving the determination, and submission to the LARWQCB prior to backfill authorization.
2.3.5.3 Rationale
The SMP addresses soil management during and following excavation but does not establish a groundwater-protective framework for conditions where contaminated soil remains in place at depth at the conclusion of excavation activities. Where excavation reaches final grade and contaminated soil is left in place, the leaching potential of residual concentrations to underlying groundwater represents a longterm loading consideration distinct from the direct-contact and airborne exposure pathways addressed by the existing SMP framework.
Groundwater beneath the Site is already impacted by contaminants above applicable regulatory thresholds and is designated for MUN beneficial use, meaning it is treated as a drinking water resource under applicable regulatory frameworks. Residual soil contamination at the base of excavations, if not evaluated against groundwater protection criteria prior to backfill, may represent an ongoing and potentially unquantified source loading contribution to an already impaired resource. This gap is significant because backfilling an excavation without a documented groundwater protection evaluation eliminates the opportunity for additional removal and creates conditions that may be difficult to reassess following construction.
2.4 Recommended Improvement 4: Sensitive Receptor Protection Protocol The presence of daycare facilities and a private elementary school within or adjacent to redevelopment parcels necessitate enhanced implementation controls beyond standard construction-phase measures.
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2.4.1 Issue
The SMP acknowledges the presence of daycare facilities (Bright Horizons Early Education and Preschool, and Hill and Dale Family Learning Center) and a private elementary school (Seven Arrows Elementary School) within the Site boundaries; however, it does not define parcel-specific enhanced protective measures for these areas. On a large redevelopment site with active soil disturbance, reliance solely on standard dust suppression and monitoring provisions may not provide a sufficient margin of safety where child receptors are present. EPA guidance recognizes that children warrant age-specific consideration in exposure assessment and that early-life exposure may increase susceptibility to certain carcinogens, supporting a more protective approach where child receptors are present (EPA, 2005a; EPA, 2005b). DTSC school-site guidance likewise identifies school properties as sensitive settings warranting particular consideration in site evaluation and community protection planning (DTSC, 2006).
Southern California precedent supports a more protective, receptor-specific approach where schools or daycare centers are present at or adjacent to contaminated sites. In the former Athens Tank Farm/Ujima Village matter in Willowbrook, the LARWQCB recommended that demolition scheduling accommodate relocation of Honey's Little Angels Daycare due to the potential impact of demolition activities on the immediate surroundings and ordered additional offsite air quality investigation at nearby residential properties where elevated VOC and methane levels were detected (LARWQCB, 2012). More broadly, California Water Boards guidance identifies occupied buildings with sensitive receptors, including schools and day-care centers, as high priority for vapor intrusion evaluation (State Water Resources Control Board, 2023).
2.4.2 Recommendation
Incorporate a Sensitive Receptor Protection Protocol applicable to parcels adjacent to or occupied by schools and daycare facilities. The protocol should include both implementation controls and governance measures and should be integrated into the Parcel-Specific Implementation Matrix.
2.4.2.1 Enhanced Implementation Controls
• Enhanced dust suppression measures, including increased water application frequency and use of soil stabilizers where appropriate.
• Continuous or high-frequency perimeter air and dust monitoring adjacent to school and daycare boundaries during active soil disturbance.
• Defined numeric action levels and corresponding response measures if monitoring thresholds are exceeded.
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2.4.2.2 Operational Restrictions
• Work-hour limitations during active school operations, where feasible. • Defined truck routing and staging restrictions to minimize proximity to sensitive receptor boundaries.
• Stockpile placement and material staging setbacks from receptor interfaces.
2.4.2.3 Governance and Communication Measures
• Advance written notification to school and daycare administrators prior to major soil disturbance activities.
• Designated point of contact for school and daycare administrators during active construction phases.
• Defined complaint response and exceedance notification pathway. • Documentation requirements for monitoring data, notifications, and corrective actions.
2.4.3 Rationale
Construction-phase activities near sensitive receptors are subject to greater scrutiny and heightened community concern than long-term modeled risk scenarios. EPA guidance recognizes that childhood exposures warrant age-specific consideration and that early-life exposure may increase susceptibility to certain carcinogens, supporting a more protective approach where child receptors are present (EPA, 2005a; EPA, 2005b). DTSC school-site guidance likewise identifies school properties as sensitive settings warranting particular consideration in site evaluation and community protection planning (DTSC, 2006).
Establishing parcel-specific sensitive receptor protocols strengthens implementation clarity, promotes consistent application of enhanced controls, and reduces the potential for community disruption or regulatory escalation. Clear definition of both operational measures and governance pathways helps ensure that protective measures are applied systematically rather than on an ad hoc basis.
2.5 Recommended Improvement 5: Clear Screening Level (SL) and Risk Framework
Risk-based decision making must be applied consistently across parcels, contractors, and redevelopment phases. Where soil screening levels may be exceeded and site-specific risk evaluations are permitted, clearly defined assumptions, target thresholds, documentation standards, and approval authority are necessary to ensure consistent and defensible implementation.
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2.5.1 Issue
The SMP allows exceedances of soil screening levels (SLs) to be evaluated through additional human health risk assessment (HHRA) calculations. However, it does not clearly define default receptor assumptions by parcel type, the target cancer risk range or hazard index threshold, the cumulative risk evaluation approach, required documentation standards, or the approval authority for alternative determinations.
Without clearly defined risk decision criteria, there is a significant risk that SL exceedances may be addressed through progressively adjusted risk calculations rather than remediation, a pattern that is inconsistent with the protective intent of the SMP and may not align with regulatory expectations for transparent and consistent risk-based decision making. The framework should therefore establish explicit thresholds, receptor assumptions, and approval pathways that prevent use of case-by-case risk evaluations as a substitute for soil removal where removal is technically feasible and protective.
On a multi-parcel redevelopment site, absence of defined risk decision criteria increases the potential for inconsistent application of SL exceedance evaluations between parcels and construction phases. DTSC guidance emphasizes transparent documentation of exposure assumptions, screening and risk evaluation methodology, and decision criteria when applying risk-based cleanup determinations, while EPA’s systematic planning and Data Quality Objectives framework emphasizes structured decision logic and predefined decision criteria rather than discretionary determinations (DTSC, 2022; DTSC, 2025; EPA, 2006).
2.5.2 Recommendation
Establish a clear Screening Level and Risk Decision Framework that integrates both governance and implementation elements.
2.5.2.1 Defined Risk Criteria (Governance Elements)
• Default receptor assumptions by parcel type, such as construction worker, commercial/industrial worker, child receptor, and residential receptor, as applicable. It is noted that the existing Site HHRA did not evaluate residential receptor scenarios, and any change in land use that introduces residential occupancy, such as the proposed mixed-use development at AIN 4272-031-005, will require preparation of an updated HHRA using residential exposure assumptions. • Explicit identification of applicable screening level sources by land use, such as DTSC and other California regulatory screening levels where applicable, and EPA Regional Screening Levels as supplemental references where site-specific risk-based concentrations are not available. • A defined acceptable cancer risk range of 1 x 10^-6 (one in one million, as the target) to 1 x 10^- 4 (one in ten thousand, as the upper bound), consistent with typical California regulatory practice, with a target of 1 x 10^-6 where feasible.
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• Clarification of cumulative risk evaluation methodology, including the treatment of multiple COPCs and multiple exposure pathways.
• Defined approval authority for alternative risk-based determinations. • Defined circumstances requiring regulatory notification or LARWQCB concurrence.
2.5.2.2 Implementation Requirements
• Standardized format for alternative risk evaluations submitted for regulatory review. • Required documentation of exposure assumptions, receptor scenarios, and input parameters. • Clear identification of the parcel or parcels to which the determination applies. • Documentation of any engineering or institutional controls relied upon in lieu of soil removal.
This framework should be integrated into the Parcel-Specific Implementation Matrix to ensure consistent application across all parcels and redevelopment phases.
2.5.3 Rationale
DTSC guidance emphasizes that risk-based determinations should be supported by clearly documented exposure assumptions, transparent screening and risk evaluation methods, and defined decision criteria.
EPA guidance on systematic planning likewise emphasizes predefined decision logic to support defensible environmental decisions (DTSC, 2022; DTSC, 2025; EPA, 2006). Without clearly defined risk thresholds and approval pathways, reliance on case-by-case evaluation may lead to variability in decision making across contractors and parcels. A structured screening level and risk framework helps ensure that alternative determinations are applied consistently, documented transparently, and remain defensible under regulatory review.
2.5.4 Regulatory Authority for No Further Action Determinations The SMP should clarify that No Further Action (NFA) determinations are made by the appropriate regulatory agency, such as the LARWQCB, not by the property owner or environmental consultant.
Where an NFA determination is sought, supporting documentation should be prepared and submitted to the LARWQCB for review and concurrence prior to any parcel-level determination that soil management obligations have been completed. This clarification strengthens governance transparency and regulatory alignment.
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2.5.5 Post-Remediation Human Health Risk Assessment Requirements The SMP requires preparation of post-remediation HHRAs following completion of remediation activities at each parcel (SMP Section 6.6). However, the SMP does not address whether the LARWQCB will direct the specific timing and format of HHRA submission, and it does not define in advance the minimum content expectations, responsible party obligations, submission pathway to the LARWQCB, whether LARWQCB review and concurrence is required before a parcel is considered complete for soil management purposes, or the relationship between post-remediation HHRA findings and any subsequent NFA determination, if required.
On a multi-parcel, phased redevelopment site, absence of defined post-remediation HHRA management standards introduces the potential for inconsistent documentation across parcels and contractors, and for parcel closure-related decisions to proceed without explicit regulatory concurrence. The SMP should be revised to define minimum post-remediation HHRA requirements, including submission timing relative to completion of remediation and confirmation sampling at each parcel; minimum content requirements, including documentation of remaining in-place soil concentrations, receptor assumptions, land use scenarios evaluated, and cumulative risk findings; identification of the responsible party for preparation and submission; the LARWQCB review and concurrence pathway prior to parcel-level closure-related determinations; and the relationship between post-remediation HHRA findings and any NFA determination as described in Section 2.5.4.
2.6 Recommended Improvement 6: Stockpile Management and Soil Movement Controls
Stockpile management and soil movement represent critical implementation control points on large, phased redevelopment sites. Where multiple excavation areas and contractors operate concurrently, clearly defined segregation, tracking, and authorization procedures are necessary to prevent crosscontamination, data gaps, and inconsistent reuse or disposal decisions.
2.6.1 Issue
The SMP restricts soil reuse to the parcel of origin unless otherwise evaluated; however, it does not establish detailed governance controls for stockpile segregation, tracking, sampling frequency, or crossparcel soil movement. On a 112-acre site with phased construction and potentially multiple active excavation areas, absence of structured stockpile management increases the potential for commingling of soils with differing contaminant profiles, inconsistent analytical characterization, cross-parcel transfer without documented risk evaluation, and reduced defensibility of reuse or disposal determinations.
EPA guidance on systematic planning emphasizes predefined decision criteria, documentation pathways, and structured decision logic to support defensible environmental decision-making. DTSC guidance likewise recognizes that soil management plans may need to address soil excavation, soil stockpiling, stockpile characterization, soil disposal, and soil reuse as part of remedial implementation. Together, these concepts support the need for a structured stockpile management and soil movement framework on a large, phased redevelopment site (EPA, 2006; DTSC, 2011).
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2.6.2 Recommendation
Establish a Stockpile Management and Soil Movement Control Framework that integrates both implementation controls and oversight controls.
2.6.2.1 Implementation Controls
• Defined stockpile segregation criteria by COPC type and concentration relative to applicable screening levels.
• Minimum sampling frequency based on stockpile volume, where not already specified in the SMP. The SMP should confirm that the proposed frequency is sufficient given the parcel-specific COPC profile and contaminant distribution variability and provide a basis for the sampling frequency selected.
• Analytical parameter selection tied to known parcel COPCs and delineated contaminant management zones.
• Physical separation of stockpiles by parcel of origin and contaminant category. • Clearly labeled stockpile identification in the field, consistent with the soil impact identification convention established in SMP Section 4.3.
• Defined measures to minimize track-out and off-site transport of contaminated soil by construction vehicles. While hazardous waste manifests are used where required for regulated waste shipments, the SMP should also establish chain-of-custody procedures for non-hazardous impacted soil loads to document origin, destination, and approval prior to departure from the Site.
These measures should include stabilized construction entrances at all active site access points, rumble strips or equivalent track-out reduction devices, and tire wash or wheel wash stations where soil conditions or activity levels warrant.
• Defined inspection, housekeeping, and escalation procedures, including defined street sweeping frequency for adjacent public roadways, daily inspection protocols for track-out conditions at site exits, and defined escalation criteria and response procedures when track-out is observed.
2.6.2.2 Governance Controls
• A unique identification system linking excavation ID, stockpile ID, analytical data, and load tickets.
• A centralized tracking log maintained throughout active construction. • Prohibition of cross-parcel soil transfer without a documented risk evaluation approved by the qualified environmental professional of record.
• Defined written approval authority prior to reuse outside parcel of origin.
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Stockpile management requirements should align with the Parcel-Specific Implementation Matrix and the Screening Level and Risk Decision Framework described in Section 2.5 to ensure consistency across all parcels and redevelopment phases.
2.6.3 Rationale
On large redevelopment sites, stockpile management is a common implementation and documentation control point. Without structured segregation, characterization, and tracking standards, soil movement decisions may become inconsistent across contractors, parcels, and construction phases. A defined stockpile management and soil movement framework helps ensure that reuse, disposal, and transfer decisions are supported by documented analytical data, clear authorization pathways, and consistent implementation procedures (EPA, 2006; DTSC, 2011).
2.7 Recommended Improvement 7: Stormwater Integration
Stormwater runoff represents a primary contaminant migration pathway during active construction. On large redevelopment sites involving soil disturbance and stockpiling, integration of soil management controls with stormwater compliance requirements is essential to prevent off-site transport and maintain regulatory alignment.
2.7.1 Issue
The SMP references stormwater controls in connection with stockpile management (SMP Section 6.4.1); however, stormwater management is not fully integrated into the broader soil disturbance implementation framework at the parcel level. While compliance with the Construction General Permit is a standard regulatory obligation, the SMP does not specify parcel-level responsible parties, minimum best management practice (BMP) requirements tied to known contaminant zones or contact water characterization and management protocols. Without these specifics, implementation may remain inconsistent across parcels and contractors even where general regulatory compliance is intended.
Given the Site's size and phased redevelopment approach, stormwater runoff and dewatering discharges1 may represent potential pathways for off-site migration of contaminated sediments or dissolved-phase constituents if not governed by structured implementation standards. The California Construction General Permit, State Water Resources Control Board Order No. 2022-0057-DWQ, regulates stormwater and authorized non-stormwater discharges associated with construction activity, identifies the discharger as the party responsible for permit compliance, requires implementation of controls, structures, and management practices to minimize or prevent pollutant discharges, and authorizes the Water Boards to require additional BMPs or revised Storm Water Pollution Prevention Plan (SWPPP) provisions to address site-specific conditions. EPA guidance on systematic planning likewise supports the use of 1 Dewatering is unlikely to be required given the depth to groundwater beneath the Site, approximately 150 feet below ground surface; however, perched water may be encountered during excavation activities and could require localized dewatering.
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2.7.2 Recommendation
Establish a Stormwater Management Framework that aligns soil disturbance governance with regulatory discharge compliance requirements and defines both implementation controls and oversight mechanisms.
2.7.2.1 Implementation Controls
• Explicit alignment with the applicable California Construction General Permit (Order No. 2022- 0057-DWQ, as amended).
• Integration with the Site-level or parcel-level SWPPP, as applicable. • Defined minimum BMPs for run-on and runoff control during soil disturbance activities. • Stabilized construction entrances and perimeter controls at all active work areas. • Covered stockpiles and secondary containment where soil contains COPCs above applicable screening levels.
• Procedures for identification and management of contact water generated during excavation activities.
• Sampling and analytical characterization requirements prior to any discharge of contact water or dewatering effluent.
• Defined treatment protocols for dewatering effluent where discharge thresholds may be exceeded.
2.7.2.2 Governance Controls
• Identification of the responsible party for Construction General Permit and SWPPP compliance at the parcel level.
• Defined documentation pathway for discharge authorization, including sanitary sewer approval, National Pollutant Discharge Elimination System (NPDES) permit coverage, or off-site disposal, as applicable.
• Integration of stormwater and dewatering controls into the Parcel-Specific Implementation Matrix for parcels with known impact zones or perched water conditions.
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2.7.3 Rationale
Stormwater runoff and dewatering activities represent key regulatory compliance obligations and potential contaminant migration pathways during active construction. Without structured integration of these requirements into the SMP governance framework, implementation may vary between parcels and contractors, increasing the potential for unintended off-site transport of contaminated sediments or dissolved-phase constituents and inconsistent discharge compliance across redevelopment phases. A defined stormwater management framework helps ensure that BMP implementation, contact water management, discharge authorization, and documentation requirements are applied consistently across all parcels and phases of work (State Water Resources Control Board, 2022; EPA, 2006).
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3. Additional Considerations: Process-Related Contaminants of Potential Concern
Historical operations at the Site included manufacturing processes characteristic of the aerospace industry during the mid-20th century, including surface finishing, electroplating, degreasing, solvent storage, and wastewater handling activities. Identification COPCs is a foundational component of a defensible conceptual site model and should reflect not only documented releases but also constituents reasonably associated with historical industrial process trains. Where process-related constituents are excluded from the COPC list, that exclusion should be supported by sufficient technical justification and analytical evidence rather than inferred solely from limited datasets or incomplete spatial characterization (DTSC, 2011; EPA, 1995; EPA, 1998).
The following subsections evaluate select process-related constituents that are reasonably associated with documented historical operations at the Site and warrant consideration within the Soil Impact Assessment and Characterization framework (SMP Section 5.0) to help ensure that the investigation remains technically complete and protective of human health and the environment.
Inclusion of these constituents in the analytical suite is a completeness and defensibility measure, not an assertion of presence. Where these constituents are not detected at method detection limits at or below the applicable screening levels, they may be screened out of the parcel-specific COPC list with appropriate documentation.
3.1 Per- and Polyfluoroalkyl Substances (PFAS) and Hexavalent Chromium (Cr(VI))
Aerospace manufacturing during the Site’s operational period commonly included surface finishing operations such as degreasing, etching, anodizing, passivation, and electroplating (EPA, 1995; EPA, 1998). These processes were integral to corrosion protection and structural durability of aircraft and missile components.
Chromium electroplating is of particular relevance. The Interstate Technology and Regulatory Council (ITRC) states that PFAS, particularly perfluorooctane sulfonate (PFOS), were used as mist suppressants added to metal plating and finishing baths to prevent air emissions of toxic metal fumes. This supports consideration of PFAS as a plausible process-related COPC in areas associated with historical chromium plating or related surface-finishing operations (ITRC, 2023).
Chromium plating uses chromic acid solutions, and Cr(VI) is directly associated with such operations.
While total chromium may have been analyzed in limited groundwater samples at the Site, chromium speciation has not been evaluated to distinguish Cr(VI) from total chromium. Because Cr(VI) exhibits distinct toxicity and mobility relative to total chromium, it represents a discrete analyte that should be evaluated independently where plating-related activities are plausible. Reliance on total chromium alone can therefore be insufficient for evaluating potential human health risk or waste handling requirements in plating-related source areas.
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Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page 22 Given the documented industrial processes and recognized source categories, PFAS and Cr(VI) are reasonably associated with historical Site operations and warrant consideration where field observations or historical infrastructure indicate potential plating-related source areas. Although EPA finalized National Primary Drinking Water Regulations for six PFAS in April 2024, EPA subsequently announced in May 2025 that it would retain the standards for PFOA and PFOS while rescinding and reconsidering the regulatory determinations for PFHxS, PFNA, HFPO-DA, and the associated hazard index mixture approach. This changing federal regulatory posture does not diminish the technical relevance of PFAS evaluation at the Site; rather, it underscores the need for a reasoned, site-specific assessment of PFAS where source history and site conditions indicate potential presence. ATSDR toxicological information for perfluoroalkyls further supports the human health relevance of PFAS evaluation.
Within the Soil Impact Assessment and Characterization framework described in SMP Section 5.0, soil samples collected during disturbance activities in areas where infrastructure or residual materials consistent with historical surface finishing or metal plating operations are encountered should include PFAS and Cr(VI) in the analytical suite. For PFAS in soil, the current EPA multi-matrix method is Method 1633A, which applies to aqueous, solid, biosolids, and tissue samples. For Cr(VI) in soil, the standard SW-846 approach is Method 3060A for alkaline digestion extraction, followed by an appropriate determinative method such as Method 7196A; where lower-level or more defensible speciation data are needed, Method 6800 may be considered as a higher-tier analytical alternative. Inclusion of these analytes does not presume their presence but ensures that potential impacts reasonably associated with documented process trains are evaluated and that exclusion, if appropriate, is supported by sufficient analytical evidence.
3.2 Consideration of 1,4-Dioxane as a Contaminant of Potential Concern Chlorinated solvents were widely used in aerospace manufacturing for degreasing and cleaning of metal components (EPA, 1995; EPA, 1998). ATSDR states that 1,4-dioxane was used primarily as a stabilizer in chlorinated solvents, particularly 1,1,1-trichloroethane, and the Interstate Technology and Regulatory Council (ITRC) likewise identifies its historical use as a solvent stabilizer and its common co-occurrence with chlorinated solvent releases (ATSDR, 2012; ITRC, 2020). 1,4-Dioxane is highly water soluble, only weakly retarded by sorption to soil, does not form a separate non-aqueous phase liquid, and is relatively resistant to biodegradation under many subsurface conditions (EPA, 2017; ITRC, 2020; ATSDR, 2012). As a result, 1,4-dioxane may migrate beyond the spatial extent of associated solvent plumes and may not be adequately characterized by monitoring networks designed primarily to define chlorinated solvent distribution. Accordingly, the absence of detections within a spatially or vertically limited monitoring network is not, by itself, a sufficient technical basis to conclude that 1,4-dioxane is absent in areas that have not yet been sampled.
In addition, 1,4-dioxane has been detected in groundwater beneath the Site. Site data indicate one exceedance of the 1 microgram per liter notification level in January 2024 in groundwater sampled from an onsite well, as well as low-level detections in an adjacent well. Boeing is currently conducting additional investigations at the Site, including the installation of additional monitoring wells, to expand and improve the current monitoring network.
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Appropriate analytical methods for 1,4-dioxane in soil may include EPA Method 8270E using selective ion monitoring, where laboratory sensitivity is adequate, or EPA Method 8260D with laboratoryvalidated low-level detection capability sufficient to achieve reporting limits at or below applicable soil screening levels. Inclusion of 1,4-dioxane in the analytical suite does not presume its presence but helps ensure technical completeness and supports defensible exclusion where appropriate.
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4. Evaluation of Phase I ESA Recommendations and SMP Alignment The Phase I ESA for 2800 28th Street (AIN 4272-031-005) identified a Recognized Environmental Condition (REC #1) associated with historical aircraft manufacturing activities and recommended two actions in connection with redevelopment of the property. The following subsections evaluate whether the current SMP sufficiently addresses each recommendation at both a conceptual and implementation level.
4.1 Phase I ESA Recommendation 1: Soil Pre-Characterization The Phase I ESA recommends collection of soil data sufficient to laterally and vertically characterize subsurface conditions anticipated to be encountered during construction activities. The intent of this recommendation is to define, in advance of redevelopment, the horizontal and vertical extent of impacted soil so that excavation planning, handling procedures, worker protection measures, and disposal pathways can be established before construction begins.
Lateral and vertical characterization, as intended by the Phase I recommendation, implies:
• Delineation of the horizontal footprint of impacted areas within the parcel boundaries. • Determination of vertical extent of impacts relative to planned excavation depths. • Identification of contaminant types and concentration ranges present within the parcel. • Integration of characterization findings into construction planning and soil management controls prior to disturbance.
The current SMP includes procedures for soil monitoring during excavation and confirmation sampling following removal. However, it does not establish a structured, parcel-specific precharacterization framework for AIN 4272-031-005.
To satisfy the intent of the Phase I recommendation, the SMP would need to define, at a minimum:
• Sampling density and spatial distribution sufficient to support parcel-level delineation. • Lateral and vertical delineation criteria to be achieved prior to disturbance. • Integration of historical operations, prior investigation data, and investigation data being generated through implementation of the Work Plans into mapped contaminant management zones.
• Survey-controlled documentation of excavation extents and confirmation sampling locations. • Inclusion of process-related COPCs, such as PFAS, Cr(VI), and 1,4-dioxane, in the precharacterization analytical suite, as discussed in Section 3 of this review.
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Recommendation 1 Alignment Determination
The SMP does not establish a defined, parcel-specific pre-characterization program for AIN 4272-031- 005 and therefore does not fully satisfy the intent of the Phase I ESA recommendation for lateral and vertical characterization of subsurface conditions in advance of redevelopment.
4.2 Phase I ESA Recommendation 2: Preparation of an SMP Using PreCharacterization Data The Phase I ESA recommends preparation of an SMP that incorporates both newly collected soil precharacterization data and existing Boeing investigation data to identify areas of concern and define special handling and disposal requirements. The intent of this recommendation is to ensure that characterization findings are formally integrated into a structured management framework before construction, rather than addressed reactively during soil-disturbing activities.
Preparation of an SMP based on pre-characterization data, as intended by the Phase I recommendation, implies:
• Integration of delineated impact zones into mapped contaminant management areas. • Definition of contaminant-specific handling, segregation, and disposal criteria tied to characterized conditions.
• Establishment of parcel-specific controls informed by known subsurface conditions. • Structured procedures for managing previously unknown conditions discovered during construction.
• Clear documentation and approval pathways for all soil management decisions.
The current SMP contains general soil handling and disturbance procedures applicable across the Site.
However, it does not define or implement a parcel-specific framework for AIN 4272-031-005 that integrates pre-characterization findings consistent with the intent of this recommendation. As discussed in Section 2 of this review, key missing elements include delineated contaminant management zones, a parcel-specific implementation matrix, defined risk decision logic, and structured stop-work and restart criteria, among others. The process-related COPCs identified in Section 3 of this review should also be incorporated into the parcel-level analytical program, as appropriate.
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Recommendation 2 Alignment Determination
The SMP provides general soil management procedures but does not establish a parcel-specific implementation and governance framework for AIN 4272-031-005 that fully integrates precharacterization findings consistent with the intent of the Phase I ESA recommendation. The improvements described in Section 2 of this review, together with incorporation of the process-related COPCs discussed in Section 3, represent the minimum framework necessary to address this recommendation at the parcel level.
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5. Conclusions
Hazen conducted a technical review of the Soil Management Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California, prepared by EA for The Boeing Company and dated December 18, 2025. The review evaluated whether the SMP, as written, is sufficiently specific and implementable to ensure consistent and defensible protection of human health and the environment during phased redevelopment of a 112-acre, multi-parcel site with sensitive receptors and a complex contamination history.
The SMP contains a structurally sound framework and a number of strong procedural elements. However, as detailed in the preceding sections of this review, the SMP requires revision in several areas before it can be considered sufficiently specific and implementable for a site of this scale and complexity. These revisions are especially critical given that housing developments are already being proposed across the Site and additional redevelopment projects are anticipated in the near term, making it essential that a more thorough and comprehensive plan be established as soon as possible.
The following subsections summarize the recommended revisions and Phase I ESA alignment determinations for the LARWQCB’s consideration in directing Boeing to revise and resubmit the SMP.
5.1 Recommended Governance and Implementation Revisions The SMP should be revised to incorporate the following seven primary improvements, including the supplemental groundwater protection measure described under Improvement 3. Boeing should be directed to address each item prior to approval of redevelopment-related SMP implementation.
Recommended Improvement 1: Parcel-Specific SMP Implementation Matrix and Parcel Maps (Section
2.1). The SMP should include a parcel-specific implementation matrix for each AIN defining current and planned land use, known COPCs and impact zones, applicable screening levels, monitoring requirements, stop-work triggers, notification pathways, and documentation standards, supported by parcel maps visually delineating AIN boundaries, contaminant impact zones, sensitive receptor locations, and monitoring applicability areas.
Recommended Improvement 2: Pre-Characterization and Delineated Contaminant Management Zones (Section 2.2). The SMP should require development and incorporation of delineated contaminant management zones based on historical operations, prior investigation data, investigation data generated through implementation of the Work Plans, and contaminant-specific behavior. These zones should be mapped laterally and vertically and referenced to individual parcels. For each zone, the SMP should define implementation and governance requirements, including mandatory pre-disturbance characterization sampling, excavation and confirmation sampling protocols, enhanced air quality, particulate, dust, field screening, and/or sampling requirements appropriate to zone-specific contaminants of potential concern, waste profiling triggers, defined decision thresholds for additional characterization or response actions, and documentation requirements prior to soil movement, reuse, or off-site disposal.
Recommended Improvement 3: Stop-Work and Restart Decision Framework with Defined Authority (Section 2.3). The SMP should include a clearly defined stop-work and restart decision framework Item 7-A
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Supplemental Groundwater Protection Measure under Improvement 3: Residual Contamination at the Base of Excavations (Section 2.3.5). The SMP should establish procedures for addressing contaminated soil that may remain at the base of excavations after final grade is reached. At a minimum, the SMP should require base-of-excavation confirmation sampling, leaching-to-groundwater evaluation criteria, defined notification thresholds, authorization prior to backfilling, and documentation requirements for any residual contamination left in place where groundwater protection may be affected.
Recommended Improvement 4: Sensitive Receptor Protection Protocol (Section 2.4). The SMP should include a sensitive receptor protection protocol applicable to parcels adjacent to or occupied by schools and daycare facilities, defining enhanced dust suppression measures, continuous or high-frequency perimeter air monitoring with defined numeric action levels, operational restrictions during active school hours, truck routing and staging setbacks, advance notification procedures, and a designated point of contact for school and daycare administrators during active construction phases.
Recommended Improvement 5: Screening Level and Risk Decision Framework (Section 2.5). The SMP should establish a screening level and risk decision framework defining default receptor assumptions by parcel type, applicable screening level tables by land use, an acceptable cancer risk range of 1 x 10^-6 to 1 x 10^-4 and a Hazard Index threshold of 1.0, cumulative risk evaluation methodology, approval authority for alternative risk-based determinations, and clarification that No Further Action determinations are made by the LARWQCB and not by the property owner or consultant. The SMP should also define post-remediation HHRA submission timing, minimum content requirements, responsible party identification, and LARWQCB review and concurrence pathway prior to parcel-level closure.
Recommended Improvement 6: Stockpile Management and Soil Movement Controls (Section 2.6). The SMP should establish a stockpile management and soil movement control framework defining stockpile segregation criteria by COPC type, minimum sampling frequency by volume and contaminant profile, physical separation requirements by parcel of origin, a unique identification system linking excavation and stockpile data, a centralized tracking log, prohibition on cross-parcel soil transfer without documented risk evaluation and written approval, and defined track-out prevention, inspection, housekeeping, and escalation procedures.
Recommended Improvement 7: Stormwater Integration (Section 2.7). The SMP should integrate stormwater and dewatering management into the soil disturbance governance framework by explicitly aligning with the California Construction General Permit (Order No. 2022-0057-DWQ, as amended), defining minimum BMPs for run-on and runoff control, establishing contact water characterization and discharge authorization procedures, identifying the responsible party for SWPPP compliance at the parcel level, and defining written approval authority prior to initiating any dewatering discharge.
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5.2 Additional Contaminant Considerations
As detailed in Section 3, the following process-related constituents are reasonably associated with documented historical operations at the Site and should be incorporated into the analytical suite for soil samples collected during disturbance activities in relevant areas. Exclusion of these constituents from the COPC list should be supported by sufficient analytical evidence rather than inferred absence.
PFAS: Soil samples collected in areas where surface finishing or metal plating infrastructure or residual materials are encountered should be analyzed for PFAS using EPA Method 1633A, or the most current EPA-validated multi-matrix PFAS method.
Hexavalent Chromium (Cr(VI)): Chromium speciation has not been evaluated at the Site to distinguish Cr(VI) from total chromium. Soil samples collected in relevant areas should be analyzed using EPA Method 3060A with an appropriate determinative method such as EPA Method 7196A, or EPA Method 6800 where higher analytical defensibility is warranted. 1,4-Dioxane: Soil samples collected in areas associated with solvent storage, degreasing operations, wastewater handling, or disposal infrastructure should include analysis for 1,4-dioxane using EPA Method 8270E with selective ion monitoring, or EPA Method 8260D with validated low-level detection capability sufficient to achieve reporting limits at or below applicable screening levels.
In addition, the potential for off-site vapor migration to nearby residential properties should be considered if existing SVE systems are modified, temporarily halted, or permanently shut down during redevelopment activities, as cessation of active vapor extraction could affect the basis for prior conclusions regarding the vapor intrusion pathway.
5.3 Phase I ESA Alignment Determinations for 2800 28th Street (AIN 4272-031- 005)
The SMP does not fully address the intent of the two recommendations identified in the Phase I ESA for 2800 28th Street (AIN 4272-031-005). Prior to approving redevelopment activities for this parcel, the LARWQCB should direct Boeing, or another responsible party as appropriate, to address the following items.
Phase I ESA Recommendation 1: Soil Pre-Characterization. The SMP does not establish a defined, parcel-specific pre-characterization program for AIN 4272-031-005 and therefore does not fully satisfy the intent of the Phase I ESA recommendation for lateral and vertical characterization of subsurface conditions in advance of redevelopment. As noted in Section 2.2, a parcel-specific pre-characterization program should, at a minimum, define sampling density and spatial distribution sufficient to support parcel-level delineation, lateral and vertical delineation criteria to be achieved prior to disturbance, integration of historical operations, prior investigation data, and existing Boeing data into mapped contaminant management zones, and inclusion of PFAS, Cr(VI), and 1,4-dioxane in the analytical suite, as appropriate, for LARWQCB review and approval prior to commencement of construction at this parcel.
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Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page 30 Phase I ESA Recommendation 2: SMP Preparation Using Pre-Characterization Data. The SMP does not fully define and implement a parcel-specific governance and implementation framework for AIN 4272-031-005 that integrates pre-characterization findings consistent with the intent of the Phase I ESA recommendation. Boeing should be directed to revise and resubmit the SMP to incorporate the parcellevel improvements described in Section 2 of this review for AIN 4272-031-005 prior to LARWQCB approval. At a minimum, these improvements should include delineated contaminant management zones, parcel-specific implementation requirements, defined risk decision logic, structured stop-work and restart criteria, and clear documentation and approval pathways for soil management decisions. The parcel-level analytical program should also incorporate the process-related COPCs identified in Section 3, as appropriate.
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Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page 31
6. References
Agency for Toxic Substances and Disease Registry (ATSDR). 2012. Toxicological Profile for 1,4- Dioxane. https://www.atsdr.cdc.gov/toxprofiles/tp187.pdf Agency for Toxic Substances and Disease Registry (ATSDR). 2021. Toxicological Profile for Perfluoroalkyls. https://www.atsdr.cdc.gov/ToxProfiles/tp200.pdf California Code of Regulations, Title 8, Section 1541. General Requirements for Excavations. https://www.dir.ca.gov/title8/1541.html
California Code of Regulations, Title 8, Section 5192. Hazardous Waste Operations and Emergency Response. https://www.dir.ca.gov/title8/5192.html
California Department of Toxic Substances Control (DTSC). 2001. Information Advisory: Clean Imported Fill Material Fact Sheet. October. https://dtsc.ca.gov/information-advisory-clean-imported-fillmaterial-fact-sheet/ California Department of Toxic Substances Control (DTSC). 2006. Interim Guidance: Evaluation of School Sites with Potential Soil Contamination as a Result of Lead-Based Paint, Termiticides, and Electrical Transformers. https://dtsc.ca.gov/wpcontent/uploads/sites/31/2018/01/School_Lead_Guidance.pdf California Department of Toxic Substances Control (DTSC). 2011. Investigation and Remediation of Plating Facilities. May. https://dtsc.ca.gov/wp-content/uploads/sites/31/2018/11/Plating_051611.pdf California Department of Toxic Substances Control (DTSC). 2022. HHRA Note 4: Guidance for Screening Level Human Health Risk Assessments. March. https://dtsc.ca.gov/wpcontent/uploads/sites/31/2022/02/HHRA-Note-Number-4-March-2022-A2.pdf California Department of Toxic Substances Control (DTSC). 2025. HHRA Note 1: Default HHRA Exposure Parameters. April. https://dtsc.ca.gov/wp-content/uploads/sites/31/2025/05/HHRA-Note-1- Revised-April-2025.pdf
Engineering Analytics, Inc. (EA). 2024. Additional Site Assessment Work Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California. Prepared for The Boeing Company. November 26. https://documents.geotracker.waterboards.ca.gov/esi/uploads/geo_report/2306899905/SLT4307472.PDF Engineering Analytics, Inc. (EA). 2025a. Additional Site Assessment Work Plan Addendum Number 1, Boeing Former Douglas Aircraft Company (DAC) Plant A, Santa Monica, California. Prepared for The Boeing Company. February 19.
https://documents.geotracker.waterboards.ca.gov/esi/uploads/geo_report/4096414506/SLT4307472.PDF Engineering Analytics, Inc. (EA). 2025b. Soil Management Plan, Former Douglas Aircraft Company Plant A, Santa Monica, California. Prepared for The Boeing Company. December 18. https://documents.geotracker.waterboards.ca.gov/esi/uploads/geo_report/2180769026/SLT4307472.PDF Item 7-A
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March 19, 2026
Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page 32 Haley & Aldrich, Inc. 2025. Report on ASTM Phase I Environmental Site Assessment, 2800 28th Street, Santa Monica, California. December 5.
Interstate Technology and Regulatory Council (ITRC). 2020. 1,4-Dioxane Technical and Regulatory Guidance. https://14d-1.itrcweb.org/
Interstate Technology and Regulatory Council (ITRC). 2023. PFAS Technical and Regulatory Guidance Document and Fact Sheets. https://pfas-1.itrcweb.org/
Los Angeles Regional Water Quality Control Board (LARWQCB). 2012. Executive Officer's Report.
July 12.
https://www.waterboards.ca.gov/losangeles/board_info/eo_reports/past_eo_report/2012/eorpt12jul.pdf South Coast Air Quality Management District (SCAQMD), Rule 1166. Volatile Organic Compound Emissions from Decontamination of Soil. https://www.aqmd.gov/docs/default-source/rule-book/regxi/rule-1166.pdf South Coast Air Quality Management District (SCAQMD), Rule 1466. Control of Particulate Emissions from Soils with Toxic Air Contaminants. https://www.aqmd.gov/docs/default-source/rule-book/regxiv/rule-1466.pdf State Water Resources Control Board. 2022. NPDES General Permit for Storm Water Discharges Associated with Construction and Land Disturbance Activities, Order WQ 2022-0057-DWQ. https://www.waterboards.ca.gov/water_issues/programs/stormwater/construction/general_permit_reissuan ce.html
State Water Resources Control Board. 2023. Final Draft Supplemental Vapor Intrusion Guidance.
February.
https://www.waterboards.ca.gov/water_issues/programs/site_cleanup_program/vapor_intrusion/docs/202 3/Final-Draft-Supplemental-VI-Guidance-Feb2023.pdf
U.S. Environmental Protection Agency (EPA). 1995. Profile of the Aerospace Industry. EPA/310-R-95- 013. https://www.epa.gov/sites/default/files/2015-09/documents/aero.pdf U.S. Environmental Protection Agency (EPA). 1998. Sector Notebook Project: Aerospace Manufacturing Industry. EPA/310-R-97-005. https://www.epa.gov/compliance/sector-notebook-project U.S. Environmental Protection Agency (EPA). 2005a. Guidance on Selecting Age Groups for Monitoring and Assessing Childhood Exposures to Environmental Contaminants. EPA/630/P-03/003F. https://www.epa.gov/sites/default/files/2014-05/documents/childrens_agegroups.pdf U.S. Environmental Protection Agency (EPA). 2005b. Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens. EPA/630/R-03/003F. https://www.epa.gov/sites/default/files/2013-09/documents/childrens_supplement_final.pdf U.S. Environmental Protection Agency (EPA). 2006. Guidance on Systematic Planning Using the Data Quality Objectives Process: EPA QA/G-4. EPA/240/B-06/001. https://www.epa.gov/sites/default/files/2015-06/documents/g4-final.pdf Item 7-A
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Technical Review of the SMP Prepared for the DAC Plant A, Santa Monica, CA Page 33 U.S. Environmental Protection Agency (EPA). 2012. Institutional Controls: A Guide to Planning, Implementing, Maintaining, and Enforcing Institutional Controls at Contaminated Sites. EPA-540-R-09- 001. December. https://www.epa.gov/sites/default/files/2015-09/documents/ic-guide.pdf U.S. Environmental Protection Agency (EPA). 2017. Technical Fact Sheet: 1,4-Dioxane. EPA 505-F-17- 001. https://nepis.epa.gov/Exe/ZyPDF.cgi/P100THWG.PDF?Dockey=P100THWG.PDF U.S. Environmental Protection Agency (EPA). 2018a. SW-846 Test Method 8260D: Volatile Organic Compounds by Gas Chromatography/Mass Spectrometry (GC/MS). Revision 4, June 2018. https://www.epa.gov/hw-sw846/sw-846-test-method-8260d-volatile-organic-compounds-gaschromatographymass-spectrometry-gcms U.S. Environmental Protection Agency (EPA). 2018b. SW-846 Test Method 8270E: Semivolatile Organic Compounds by Gas Chromatography/Mass Spectrometry (GC/MS). Revision 6, June 2018. https://www.epa.gov/hw-sw846/sw-846-test-method-8270e-semivolatile-organic-compounds-gaschromatographymass-spectrometry U.S. Environmental Protection Agency (EPA). 2021. Revitalization-Ready: A Guide to Revitalizing Land in Your Community. EPA Office of Brownfields and Land Revitalization. December. https://www.epa.gov/system/files/documents/2021-12/revitalization-ready-guide-final-508compliant-12- 10-21.pdf
U.S. Environmental Protection Agency (EPA). 2024a. PFAS National Primary Drinking Water Regulation. 89 Fed. Reg. 32532. April 26, 2024. https://www.epa.gov/sdwa/and-polyfluoroalkylsubstances-pfas U.S. Environmental Protection Agency (EPA). 2024b. Method 1633A: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS.
December 2024. https://www.epa.gov/cwa-methods/method-1633-analysis-and-polyfluoroalkylsubstances-pfas-aqueous-solid-biosolids-and-tissue U.S. Environmental Protection Agency (EPA). n.d. SW-846 Test Method 3060A: Alkaline Digestion for Hexavalent Chromium. https://www.epa.gov/hw-sw846/sw-846-test-method-3060a-alkaline-digestionhexavalent-chromium U.S. Environmental Protection Agency (EPA). n.d. SW-846 Test Method 6800: Elemental and Molecular Speciated Isotope Dilution Mass Spectrometry. https://www.epa.gov/hw-sw846/sw-846-test-method6800-elemental-and-molecular-speciated-isotope-dilution-mass-spectrometry U.S. Environmental Protection Agency (EPA). n.d. SW-846 Test Method 7196A: Chromium, Hexavalent (Colorimetric). https://www.epa.gov/hw-sw846/sw-846-test-method-7196a-chromium-hexavalentcolorimetric Item 7-A
September 22, 2026
Item 7-A
September 22, 2026
Los Angeles Regional Water Quality Control Board
June 24, 2026
Mr. Clare Thomas
President
Friends of Sunset Park
P.O. Box 5823
Santa Monica, CA 90409
SUBJECT: COMMENTS ON THE FRIENDS OF SUNSET PARK LETTER DATED MARCH 19, 2026
SITE: THE BOEING COMPANY, FORMER DOUGLAS AIRCRAFT COMPANY PLANT A, 3000 OCEAN PARK BOULEVARD, SANTA MONICA,
CALIFORNIA (SCP NO. 0130B, SITE ID NO. 2043H00, GLOBAL ID SLT4307472)
Dear Mr. Thomas:
Los Angeles Regional Water Quality Control Board (Los Angeles Water Board) staff have received your letter dated March 19, 2026 (Letter), which arrived via email on March 24, 2026, regarding comments on the residential development activities in the Santa Monica Business Park and on issues previously raised in a letter dated February 7, 2024.
Friends of Sunset Part Comments
The Letter submits comments based on information obtained from the 2023 Historic Use Analysis of the Business Park, the 2025 Public Participation Plan as well as the City of Santa Monica sponsored public outreach programs presented by developers concerning proposed developments of two side-by-side 8-story multi-unit residential buildings at 2716 Ocean Park Boulevard and 2800 28th Street. The following are your concerns (italicized verbatim) documented in the Letter followed by Los Angeles Water Board staff responses to your comments:
1. The Letter indicates that documents referenced above and submitted to the Los Angeles Water Board are not a proper substitute for California Environmental Quality Act (CEQA) review, which is designed and intended to allow far more rigorous public comment and participation, through the formal legal processes established by statute. Nor does anything in the reports justify avoidance of a full remediation requirement of the subject properties. Because it appears that things are proceeding apace under the public radar, this is causing concern for our members.
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Responses:
a. The 2023 Historic Use Analysis of the Business Park and the 2025 Public Participation Plan were not intended to be a substitute for the CEQA review process. These documents were created before any proposed redevelopment and pertain to the entire Boeing Former Douglas Aircraft Company Plant A Site (Site) which environmental site assessment and cleanup activities are being overseen by the Los Angeles Water Board Site Cleanup Program (SCP). The City of Santa Monica is the Lead Agency for the CEQA related to the proposed redevelopment projects at 2716 Ocean Park Boulevard and 2800 28th Street. The Los Angeles Water Board was not involved in any city-sponsored public outreach programs presented by developers as referenced in the Letter.
b. The 2023 Historical Use Analysis of the Business Park prepared by Advisian was used to identify data gaps and determine where additional site assessment activities may be needed for the Site.
c. The goal of the Site’s 2025 Public Participation Plan prepared by Engineering Analytics was to develop a strategy to identify and address potential stakeholder concerns and establish effective channels of communication between the community and other stakeholders, the Los Angeles Water Board, and Boeing, in order to understand and prepare to respond to community concerns and questions about the Site, inform the community of the progress of activities associated with the Site, and provide opportunities for the community to comment on the Site. d. Boeing is completing ongoing remediation activities at the Site. Community outreach activities have been conducted and they’re ongoing, which included the distribution of a number of Fact Sheets and work notices to inform the community of various Site activities.
2. Our organization is concerned that the developers’ public outreach and the “Public Participation Plan,” as circulated, are materially inadequate because they do not clearly explain to our residents, or the decision-makers, or prospective occupants, the continuing health and safety significance of unresolved volatile organic compound (“VOC”) contamination underlying portions of the former Douglas Aircraft Company Plant A area, including the portions extending westward toward 25th Street and the parcels now under consideration for high-density residential development at 2716 Ocean Park Boulevard and 2800 28th Street.
Response:
a. As previously noted, the Los Angeles Water Board is the regulatory agency overseeing Boeing’s site assessment and cleanup work at the Site. The two proposed development activities are located within the Site. Los Angeles Water Board staff are currently working with Boeing, the developers, and Item 7-A
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the City of Santa Monica to make sure the Site is suitable for its intended use. The Los Angeles Water Board was not part of the developers’ public outreach activities and will continue conducting our own public participation associated with Boeing’s site assessment and cleanup.
3. The technical materials referenced in the underlying site reports identify continuing unresolved contamination concerns in Subareas C, D, E, and F, including: persistent high VOC concentrations in field gas zones underlying former source areas despite more than a decade of soil vapor extraction; documented historical presence of Trichloroethylene and 1,1-Dichloroethylene in soil vapor and perched groundwater to depths approaching 90 feet below ground surface; downgradient detections indicating possible continuing plume migration; acknowledged need for further lateral and vertical delineation, including westward migration concerns toward Clover Park and adjacent residential areas.
Response:
a. The Los Angeles Water Board acknowledges the residual contamination concerns identified in Subareas C, D, E, and F, including persistent VOC concentrations in soil vapor and groundwater, potential plume migration, and remaining data gaps related to the lateral and vertical extent of impacts.
The Los Angeles Water Board is currently working with Boeing to complete additional site assessment and remediation activities to ensure the Site is suitable for its intended use. Current assessment activities include expanded soil, soil vapor, and groundwater investigations intended to further delineate the nature and extent of contamination, evaluate potential migration pathways, and address identified data gaps, including areas toward Clover Park and adjacent residential areas.
4. The Public Participation Plan does not explain in plain language that these contaminants present potential vapor intrusion risks to future residents, particularly; children, pregnant women, elderly occupants, and persons subject to long-duration indoor exposure.
Response:
a. The Public Participation Plan describes how project information will be provided to the local community and other interested stakeholders concerning the Site activities being performed at the Site. It would not be the document that provides information on the contaminants of concern at the Site. Information about the contaminants of concern at the Site can be found at on the State Water Resources Control Board GeoTracker database (GeoTracker) under the Summary tab at the following location:
https://geotracker.waterboards.ca.gov/profile_report.asp?global_id=SLT43 07472.
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SCP No. 0130B
The Los Angeles Water Board will continue providing project updates and fact sheets to the community in plain language regarding the ongoing environmental investigations of VOCs in soil, soil vapor and groundwater.
Previous public communications issued by the Los Angeles Water Board can also be found on GeoTracker under the Community Involvement tab.
5. We are specifically concerned about proposals for residential development at 2716 Ocean Park Blvd and 2800 28th Street, and any other proposals in Subareas C, D, E, and F, in light of the documented presence of volatile organic compounds (VOCs) in soil vapor, perched groundwater, and the regional aquifer beneath and downgradient of these areas. The 2023 “Historical Use Analysis Report” by Advisian for the Santa Monica Airport area, as far as we can tell, identifies numerous problems to be addressed, listed at pp 94-95, including but not limited to:
• Persistent, elevated VOC concentrations in fine grained zones beneath the former DAC Plant A area that have not significantly decreased after many years of soil vapor extraction, indicating a long-term subsurface VOC reservoir.
• Historical detections of trichloroethylene (TCE) and 1,1dichloroethene (1,1DCE) in soil vapor and perched groundwater in the vadose zone (to depths of approximately 90 feet) along the western portion of the site, and a clear recommendation for additional lateral and vertical delineation, including within and beneath Clover Park.
• Consistent detections of 1,1DCE at monitoring well MW8 in the regional aquifer downgradient of the site since 2019, suggesting an actively migrating VOC plume whose full extent and behavior are not yet fully understood.
• An explicit warning that before Airport #1 WSW or any proposed water supply wells in the area are brought into production, potential changes to the groundwater flow regime and effects on contaminant concentrations must be evaluated, along with further vadose zone characterization to understand VOC migration to the regional aquifer.
These findings underscore that the subsurface conditions remain incompletely characterized and that significant contamination persists in both the vadose zone and groundwater. While such conditions are already a cause for concern for commercial and industrial uses, they are fundamentally incompatible with high density residential development—especially when that development would house children, pregnant women, and other sensitive populations.
Item 7-A
September 22, 2026
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September 22, 2026
Mr. Clare Thomas - 5 - June 24, 2026
Friends of Sunset Park
SCP No. 0130B
Response:
a. The Los Angeles Water Board agrees that the Historical Use Analysis Report identified various Site data gaps. This document was used to aid in the development of a work plan to conduct additional Site assessment activities.
b. These Site assessment activities are currently being conducted and a report documenting the results is due to the Los Angeles Water Board via GeoTracker by October 30, 2026. Based on the data collected the need to expand the current remediation system will be evaluated.
6. Per City of Santa Monica Planning Ordinance, a Phase 2 ESA site investigation is required for the entire Business Park property prior to construction of multi-family residential housing. The field efforts should include soil vapor, soil, and groundwater sampling and chemical analysis for PCOC to protect public health and safety. BXP and Watt will be required to determine the extent of the contamination on their parcels.
Response:
a. As indicated above, additional Site assessment activities are currently being conducted by Boeing. It should be noted that the City of Santa Monica Planning requirements are separate from the Los Angeles Water Board requirements.
7. The March 9, 2026, “Limited ESA Phase II Report” states (page 3) that the BXP 2800 28th St site’s subsurface soil vapor is impacted at concentrations that present a “potential vapor intrusion risk,” i.e., above regulatory thresholds. This is substantial evidence documenting a need for a fulsome assessment of the clear risk to public health and safety at the site.
Investigation activities conducted at the Site have also identified deeper soil and groundwater impacts, which are being addressed by Boeing under oversight by the LARWQCB, Case # 0130B. This Work Plan does not include further assessment of the Site’s deeper impacted soil and groundwater, as BXP’s redevelopment planning does not require the collection of additional deeper data The redevelopment of the Site will encompass the entire parcel; therefore, there will be no direct exposure to future Site occupants following the construction of the building. Similarly, the Site’s planned excavation will not extend to groundwater, which has been measured to be first encountered as perched groundwater at approximately 70 feet bgs. This Work Plan excludes the collection of additional soil vapor data, as it is already established that the Site’s subsurface soil vapor is impacted at concentrations that present a potential vapor intrusion risk. Given this concern, BXP will be installing a VIMS when constructing the Site’s new building, and further soil vapor data is not required to design the VIMS.
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September 22, 2026
Item 7-A
September 22, 2026
Mr. Clare Thomas - 6 - June 24, 2026
Friends of Sunset Park
SCP No. 0130B
Response:
a. As a point of clarification, the “Limited ESA Phase II Report” is actually the Limited Phase II Environmental Site Assessment Work Plan. This work plan was not intended to be used to completely assess the Site’s soil and groundwater contamination. The work plan was developed in order to characterize the current soil conditions for on-site soil management and proper off-site disposal. The data collected from this assessment will allow for the evaluation of potential risks associated with the excavation activities and waste profiling for future off-site disposal. As previously indicated, Boeing is working with the Los Angeles Water Board and is currently conducting additional Site assessment activities to identify any additional data gaps and determine the need to expand the current Site remediation and assessment activities.
8. This report seems to imply that “all will be taken care of” by installation of a VIMS.
However, installing a VIMS is not sufficient to protect occupants of a residential building; a VIMS is insufficient to mitigate risk to sensitive residential occupants, as this Guidance from the San Francisco RWQB indicates: “Relationship Between VIM and Remediation In general, the Regional Water Board considers VIM as an interim measure that is not a substitute for remediation of VFCs in the subsurface.
In most cases, for new construction where a VIMS is needed to protect building occupants, we will not approve the VIMS until remediation to the extent feasible has been implemented. This could affect the local agency’s permitting decision for occupancy. Cleanup is the best way to reduce the magnitude of VI exposure that could occur if problems arise with VIMS, and it is the best way to reduce the timeframe over which VIMS are needed. Nonetheless, VIMS are often necessary since achieving cleanup standards may take years given currently available remedial technologies. Additionally, VIM may be the only viable long-term response action where remediation is infeasible (e.g., further concentration reductions are not possible and residual concentrations pose a VI threat).(S.F.
RWQB Vapor Intrusion Mitigation Guidance, p.3; emph. added) Response:
a. As previously indicated soil vapor remediation is currently on-going at the Site. VIMS is not proposed to be the only remediation action that will occur at the Site, but rather an interim protective measure while assessment and remediation efforts continue. Los Angeles Water Board staff is working with Boeing to further assess, delineate, and remediate soil vapor and groundwater impacts to ensure the Site is suitable for its proposed use. In addition, occupancy of residential buildings would only be allowed once the necessary assessment, remediation, and confirmation sampling demonstrate that conditions are protective of residential use and human health.
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September 22, 2026
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September 22, 2026
Mr. Clare Thomas - 7 - June 24, 2026
Friends of Sunset Park
SCP No. 0130B
9. CEQA Review is Warranted
Response:
a. The City of Santa Monica is the agency that will make the determination on whether a full CEQA review is needed for the redevelopments or whether ministerial review will suffice. The Los Angeles Water Board is not involved in the CEQA process for these redevelopments at this time.
Friends of Sunset Park Requests and Recommendations:
1. Full, Health Protective Remediation Before Any Residential Approvals • The RWQB and City of Santa Monica should not approve any discretionary entitlements, rezonings, or permits that enable residential development in Subareas C, D, E, and F until the Regional Water Quality Control Board has determined that all relevant media—soil, soil vapor, perched groundwater, and the regional aquifer—have been fully investigated and remediated to standards appropriate for unrestricted residential use, including protection of children and pregnant residents.
• Remediation must specifically address the persistent VOC reservoirs in the fine-grained zones beneath the former DAC Plant A and any other identified source areas, with clear, measurable performance objectives based on actual reductions in VOC mass and concentrations, not simply operating time for remediation systems.
Responses:
a. The Los Angeles Water Board concurs with these comment and is currently working with Boeing and the developers, as well as the City of Santa Monica staff to ensure any proposed developments are protective of the intended uses.
b. Site assessment activities are currently on-going. Based on results and data, the need for additional Site remediation activities by Boeing will be evaluated as warranted.
2. Completion of Subsurface Characterization and Plume Delineation • The additional lateral and vertical delineation of soil vapor and perched groundwater recommended in the 2023 investigations—particularly to the west and into Clover Park—should be completed and made publicly available before any residential entitlements are considered.
• The VOC plume in the regional aquifer, including but not limited to 1,1DCE detections at MW8 and any other downgradient wells, should be fully Item 7-A
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delineated and modeled, demonstrating that the plume is under control and trending toward cleanup rather than expansion.
Responses:
a. As stated in the previous responses, additional site assessment activities are currently being completed at the Site by Boeing, and the results of these activities are due to the Los Angeles Water Board by October 30, 2026. b. Based on the results of the Site assessment activities currently being completed at the Site, additional groundwater monitoring wells will be installed if warranted. A groundwater monitoring program is also currently on-going. The groundwater monitoring plan is re-evaluated every 2 years.
3. Integrated Evaluation of Groundwater Pumping and Land Use Change • Any decision to activate or modify Airport #1 WSW or other water-supply wells in the area must be evaluated together with proposed land-use changes, including residential redevelopment, recognizing that groundwater pumping can alter plume behavior and vapor-intrusion potentials beneath existing and future buildings.
• A combined analysis should be required, examining how different pumping scenarios may affect VOC concentrations at supply wells and within underlying soils and vapors beneath current and proposed residential areas.
Response:
a. As the water purveyor for the aforementioned wells, the City of Santa Monica would make the determination to activate or modify Airport #1 WSW or other water supply wells in the area.
4. Residential and Child Focused Health Risk Standards
• Cleanup and closure decisions must be based on exposure assumptions and target levels appropriate for 24-hour-per-day, long-term residential occupancy, including infants, children, and pregnant residents, not on less protective commercial/industrial worker scenarios.
• A quantitative health risk assessment should be required that explicitly evaluates chronic and sub chronic indoor air exposure to TCE, 1,1DCE, and related VOCs for sensitive populations, as well as potential drinking water exposure if groundwater is or may be used.
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September 22, 2026
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September 22, 2026
Mr. Clare Thomas - 9 - June 24, 2026
Friends of Sunset Park
SCP No. 0130B
Responses:
a. Human health risk assessments have been completed at the Site that consider the current and anticipated land uses at the time each risk assessment was completed. In addition, certain risk assessments have evaluated hypothetical residential and child exposure scenarios. These health risk assessments, along with other Site-related documents are available on GeoTracker at the following location:
https://geotracker.waterboards.ca.gov/profile_report.asp?global_id=SLT43 07472.
Prior to Site closure or occupancy of future buildings, additional human health risk assessments will be conducted as new data becomes available and, if warranted, to ensure that human health and the environment remain protected. In addition, confirmation indoor air sampling will need to be completed for the proposed residential developments before residential occupancy is permitted.
b. All HHRA’s have been reviewed and will continue to be reviewed by toxicologists with the Office of Environmental Health Hazard Assessment (OEHHA).
5. Enforceable Long-Term Protections and Monitoring
• If, even after aggressive remediation, residual contamination remains that could contribute to vapor intrusion, residential development should only proceed with enforceable engineering controls (e.g., sub-slab depressurization, vapor barriers) and robust long-term monitoring programs that are clearly funded, maintained, and periodically reviewed for the life of the buildings. • Institutional controls, including land use covenants, requirements for periodic reevaluation of site conditions, and disclosure requirements for future occupants, should be mandatory components of any approval for residential use on or near affected areas.
Response:
a. The Los Angeles Water Board agrees that residual contamination may warrant the need for engineering controls as well as institutional controls such as a Land Use Covenant that provides for long-term monitoring to be put in place.
6. Transparent, Coordinated Oversight and Public Process • The City should conduct a full project specific environmental review, consistent with CEQA, that incorporates the most current data and requirements from the Item 7-A
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Item 7-A
September 22, 2026
Mr. Clare Thomas - 10 - June 24, 2026
Friends of Sunset Park
SCP No. 0130B
Regional Board, and that directly addresses whether site conditions are safe for residential development with child sensitive receptors. • The Regional Board should clearly state whether the remedial approach and any prospective closure determinations are intended to support unrestricted residential use and, if so, the technical basis and conditions (including monitoring and contingency measures) for that conclusion.
Responses:
a. Comment noted. This request should be directed to the City of Santa Monica since the Los Angeles Water Board does not have the authority to require the City to conduct a full project specific environmental review. b. Comment noted. Once the Site meets the Los Angeles Water Board closure requirements, a no further action letter will be issued and the letter will indicate if there are any restrictions associated with the property.
7. Our February 7, 2024, letter to the Regional Board raised our concerns only from the perspective of clean-up costs impacting affected neighborhood association as taxpayers. This (new) joint communication to both the City and the Regional Board is intended to make clear that Friends of Sunset Park strongly opposes moving forward with residential development in Subareas C, D, E, and F until the subsurface conditions are thoroughly characterized, aggressively remediated by the property antecedent owners/users , and demonstrated to be protective of long-term residential use, particularly for children.
Responses:
a. Comment noted. Friends of Sunset Park’s March 19, 2026, communication clarifies that, in addition to concerns previously raised in the February 7, 2024, letter regarding potential cleanup costs and taxpayer impacts, the organization also opposes moving forward with residential redevelopment in Subareas C, D, E, and F until subsurface conditions are adequately characterized, appropriate remediation has been completed by the responsible parties, and the Site is demonstrated to be protective for longterm residential use, including sensitive receptors such as children. As previously noted, the Los Angeles Water Board is overseeing ongoing site investigation and remediation activities being conducted by Boeing to further characterize soil, soil vapor, and groundwater conditions and to address remaining data gaps and contamination concerns. Decisions regarding redevelopment and land use approvals fall under the authority of the City of Santa Monica and other local agencies; therefore, the March 19, 2026, communication should also be shared with the City for consideration as part of any redevelopment review process.
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September 22, 2026
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September 22, 2026
Mr. Clare Thomas - 11 - June 24, 2026
Friends of Sunset Park
SCP No. 0130B
Thank you for your interest in the Site activities. All reports and correspondences for the Former Boeing Santa Monica DAC Site, including this March 19, 2026, and the February 7, 2024, letters from Friends of Sunset Park have been uploaded to the GeoTracker database.
Should you have any further questions related to this project, please contact Ms.
Ana Townsend at (213) 576-6738 ([email protected]) or Mr.
Joshua Cwikla, Supervisor, Site Cleanup Program Unit I, at (213) 576-6735 ([email protected]).
Sincerely,
__________________
Susana Arredondo
Executive Officer
cc: E-Mailing List
Lisette A. Gold, City of Santa Monica
Monica Hanley, City of Santa Monica
John Scott, The Boeing Company
Ken Puentes, Engineering Analytics, Inc.
Marlene Jurgensen, SNAP CHAT
Nana Wilberforce, SNAP CHAT
Kathleen Goodhart, Cooley, LLP
Reece Trevor, Cooley, LLP
Renee Van De Griend, PhD, PE, Ramboll
Danny Murtagh, BXP (SMBP LLC)
Kara Russel, SMBP LLC
Roberta Irish, Transpacific Development Company (SCE Enterprises SMB, LLP) Item 7-A
September 22, 2026
Item 7-A
September 22, 2026
August 11, 2026 Email from 311 System responding to request from FOSP to Planning Sta? re CEQA evaluation of Airport Business Park
Item 7-A
September 22, 2026
Item 7-A
September 22, 2026