08-31-26 Update on Soil Remediation

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August 31, 2026

As part of the ongoing soil remediation and campus modernization at Longfellow Elementary School, the Pasadena Unified School District (PUSD) has determined that several large, mature trees on the school’s front lawn that meet or are being treated as meeting the District’s protected-tree criteria will need to be removed in order to fully remediate contaminated soil beneath and around them.

The District understands the significance of this decision. These are prominent, mature trees that have been part of the Longfellow campus for generations. We know their removal will be painful to many members of the school community and to Pasadena residents who care deeply about the city’s tree canopy.

The California Department of Toxic Substances Control (DTSC) has reviewed the District’s latest front-lawn excavation analysis and confirmed that a significant quantity of contaminated soil remains within the critical root zones of these trees. In its August 31, 2026 letter, DTSC further stated that this soil, and “infrastructure, trees, and vegetation that impede removal of contaminated should be removed and replaced” for the site to receive a No Further Action determination and to support the state matching funds associated with the Longfellow modernization project.

The Board Directed PUSD to Try to Save These Trees

In June, the Board directed District staff to preserve protected native and mature trees wherever feasible and to exhaust reasonable alternatives before considering their removal. At Longfellow, the District has done exactly that.

Six mature or protected trees remain on the front lawn. One of them, Tree 98, was not originally identified as protected in the tree inventory provided to the District, but PUSD is treating it as protected and applying the same preservation standard and analysis as to the other protected trees. These trees continued through the preservation analysis described below.

Air Knifing

To determine whether contaminated soil could be removed while preserving the trees, contractors and arborists used a technique commonly known as air knifing, which uses compressed air and vacuum excavation to carefully expose soil and roots while minimizing damage to the tree.

All six trees were evaluated in this manner to a depth of approximately six inches and, in some locations, as much as one foot. Testing of the soil exposed during that process continued to show elevated lead levels.

The District’s arborists concluded that removing additional contaminated soil from around the root systems would destabilize structural roots and create a high likelihood of tree failure. DTSC reviewed that analysis and stated that “infrastructure, trees, and vegetation that impede removal of contaminated soil should be removed and replaced as part of the removal action.” Because the trees block removal of contaminated soil, DTSC also determined that standard excavation methods requiring tree removal would therefore be necessary to remove the contaminated soil.

In other words, the alternative excavation technique the Board specifically directed staff to pursue to preserve protected trees was tried. It did not provide a safe way to both preserve the trees and fully remove the contaminated soil.

Bioremediation

The District also evaluated whether the contamination could be addressed through bioremediation.

Bioremediation can sometimes be useful when contaminant concentrations are at a low enough level and site conditions allow contaminants to be treated or managed over time. At Longfellow, however, the concentrations of lead present in the soil, the location of the contaminated soil, and the requirements of the state-overseen cleanup make that approach neither sufficiently reliable nor feasible.

It can also take years to achieve meaningful results, requiring the area to be closed off until contaminants are removed from the soil. For an elementary school campus undergoing comprehensive modernization, that is not a workable long-term solution.

Soil Capping

Another potential option would be to leave contaminated soil in place and isolate it beneath an impermeable surface such as asphalt or concrete.

But this option would mean knowingly leaving contamination on an elementary school campus. DTSC has stated that contaminated soil left on the campus would require long-term institutional controls, such as a land use covenant, to manage it. Such controls would restrict how the property is maintained, excavated, renovated, or altered in the future because contamination remains in place. It would also complicate future campus work and modernization, and leave students with a hardened surface rather than restored green space.

Longfellow students are currently housed at another campus while their school undergoes a comprehensive, bond-funded modernization. That has allowed the District to evaluate these options deliberately rather than make decisions around an immediate school-opening deadline. It also makes this the appropriate time to address the contamination comprehensively rather than leave it beneath a newly modernized campus.

Removal as a Last Resort

There is no version of this decision in which PUSD benefits from removing mature trees unnecessarily. The District knows the concern and criticism their removal will generate.

If there were a safe and workable alternative that allowed us to preserve these trees, fully remove the contamination and return the property to unrestricted educational use, we would take it. After additional testing, air-knifing, arborist review and evaluation of alternative remediation methods, our environmental and tree professionals have concluded that there is not.

DTSC has also stated that removal and replacement of contaminated soil is necessary to ensure the continued safe use of the site and that trees and vegetation that impede that removal should be removed and replaced as part of the cleanup.

This remains fundamentally a soil-remediation project, not a tree-removal project. The District’s responsibility is to remove contamination, complete the modernization of Longfellow, and ultimately return students to a safe, healthy, and green campus.

Replanting and Canopy Restoration

PUSD has committed to planting at least one replacement tree for every tree removed. Replacement planting will follow the District’s 2026 Landscape and Exterior Space Guidelines, which incorporate current fire-resilient design principles and approved plant palettes emphasizing native, drought-tolerant, and locally adapted species, as well as trees selected to provide meaningful long-term shade for students.

That commitment is part of a broader long-term goal the Board adopted on August 27: to preserve and expand PUSD’s existing tree canopy and to work toward at least 30 percent mature tree canopy coverage in outdoor areas used for student learning, play, and circulation by 2035. The resolution also directs the District to use its landscape guidelines and approved plant palettes to guide tree selection, placement, irrigation, and long-term care, and calls for annual updates to the tree inventory and public reporting on progress.

DTSC’s approved cleanup plan itself also anticipated that mature trees in the front lawn would need to be removed and recommended replacing them with appropriately sized trees consistent with new construction.

The removal of these particular trees is a difficult exception within a broader commitment to human health and safety, as well as to the preservation, replacement, and long-term canopy growth across PUSD campuses.

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