McKinley Elementary School Removal Action Workplan

McKinley Elementary School Removal Action Workplan

The Department of Toxic Substances Control (DTSC) has approved the Removal Action Workplan (RAW) for a 0.99-acre (Site) portion within the 6.50-acre McKinley Elementary School campus (campus) located in Santa Monica. The RAW encompasses cleanup activities at the Site located along the northeastern portion of the campus and associated with renovation and modernization activities planned at the campus. The campus is bounded by Santa Monica Boulevard to the southeast, Chelsea Avenue to the northeast, Arizona Avenue to the northwest, and 23rd Court (alley) to the southwest and located approximately 0.60 miles north of Interstate 10 (1-10), 2.0 miles east of the Pacific Coast Highway (PCH) and Santa Monica State Beach. The RAW addresses the presence of soils impacted with arsenic and soil vapor impacted with volatile organic compounds (VOCs) at the Site at concentrations above applicable screening levels. Implementation of the RAW includes capping and containment of arsenic-impacted soils, installation of a Vapor Intrusion Mitigation and Migration Engineering Controls (VIMMEC) system to address VOC-impacted soil vapor, plus execution of land use restrictions, and approval of an operation and maintenance plan. The cap will be comprised of pavement and the classroom structure itself. The cap will be used to eliminate the potential for human contact with arsenic-impacted soil. Undisturbed soils, including those impacted with arsenic, will remain on the Site and any soils disturbed during construction activities will be excavated only for the purposes of compaction and placement beneath pavement or the classroom structure. Additionally, in landscaped areas, exposed soil will be replaced by approximately four feet of clean landscaping materials such as mulch and topsoil. The VIMMEC system will consist of a barrier membrane and a passive vapor collection system beneath the proposed building slab. The vapor barrier will consist of an impermeable membrane that will be installed beneath the building slab to reduce the potential for subsurface vapors to enter the building. The membrane will consist of a sprayed-in-place continuous bituminous barrier system. The passive vapor collection system will be installed beneath the vapor barrier and will consist of a connected array of low-profile collection/infiltration piping installed in a high permeability layer (such as gravel) beneath the building slab. The vent piping will be connected to vent riser exhaust stacks. The venting system will be designed to function under passive conditions (i.e., venting will occur via natural processes without powered blowers). As a contingency measure, the venting system will also be designed to operate under both passive and active operating conditions utilizing a vacuum blower to further reduce levels of vapors (as necessary) under active operation. Project activities will involve the use of a backhoe, loader, excavator, and/or shovels, as necessary. As soil is excavated, it will be temporarily staged for use throughout the Site prior to replacement and compaction. Project activities will be implemented in accordance with applicable South Coast Air Quality Management District (SCAQMD) rules and regulations, including Rule 1466 concerning arsenic-impacted soils and Rule 403 concerning fugitive dust emissions. Remediation activities will occur concurrently with Site preparation and construction activities associated with campus renovation and modernization activities over a period of 2 to 3 months. The cleanup activities will be required to comply Santa Monica Municipal Code Section 4.12.110, which limits the hours of construction to 8:00 a.m. to 6:00 p.m. on weekdays and 9:00 a.m. to 5:00 p.m. on Saturday; and prohibits construction on Sundays and holidays. Following completion of construction activities, a land use restriction will be executed between DTSC and the property owner and recorded with the Los Angeles County Recorder’s Office to ensure future uses of the property are consistent with the operation and maintenance of the cap and VIMMEC system and to ensure the cap and VIMMEC system are properly maintained. An operation and maintenance plan will be submitted and approved by DTSC that would specify the maintenance and monitoring requirements. Background: On June 1, 2023, the Santa Monica-Malibu Unified School District (SMMUSD) certified an Environmental Impact Report (EIR) for the McKinley Elementary School Campus Master Plan Project (SCH No. 2023010230). The EIR evaluated potential environmental impacts associated with renovation and modernization activities that SMMUSD plans to undertake at the existing campus, which includes the entirety of the cleanup Site. The EIR includes mitigation measures addressing potential impacts to Cultural Resources, Geology and Soils, Hazards and Hazardous Materials, Noise, and Transportation. The EIR anticipated cleanup activities would potentially need to be conducted at the Site as part of the campus renovation and modernization activities, thus the EIR included discussion and analysis specific to Site remediation activities and mitigation measure (Mitigation Measure HAZ-2) specifically requiring Site remediation. On May 2, 2024, SMMUSD approved an Addendum to the previously adopted EIR. The EIR Addendum addressed a change in the cleanup approach from what had been contemplated in the original EIR (excavation and off-Site disposal of contaminated soils) to the approach now set forth in the subject RAW (containment and capping-in-place of arsenic-impacted soils, and installation of a VIMMEC system to address VOCs in soil vapor). As part of addressing the change in cleanup approach, Mitigation Measure HAZ-2 was modified for consistency with the modified implementation activities. DTSC determined that SMMUSD’s prior environmental review adequately encompasses potential environmental impacts associated with the activities and measures identified in the RAW, and that for purposes of CEQA, no further analysis is required. (Refer to the Statement of Findings for additional information.) Therefore, DTSC prepared a Statement of Findings concluding the Lead Agency Final Environmental Document adequately analyzed the impacts associated with the implementation of the RAW.

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