Overview 

The Mill Valley Middle School Modernization Project proposes to demolish the existing 1960s era buildings at the preferred site of the existing school campus and replace them with a modern, two-story classroom building. Before construction begins, the Mill Valley School District (MVSD) will conduct a site investigation, called a Preliminary Endangerment Assessment or PEA, to evaluate historical environmental issues at the campus, and complete an Environmental Impact Report (EIR) in accordance with the California Environmental Quality Act (CEQA).  

Draft Environmental Impact Report (DEIR)

The MVSD Board of Trustees are responsible for all decisions on the middle school modernization project. Under CEQA, the project will be evaluated in a Draft Environmental Impact Report (DEIR) which will include analysis of its potential to cause significant impacts to the environment, including impacts on resources like air quality, water resources, traffic and circulation, and human health and safety. The DEIR also analyzes several other project scenarios, including a “no project” alternative, and evaluates other locations for the permanent and interim campuses, including alternatives proposed by the community.

A critical step in the environmental review process is making the DEIR available for public review and comment. The public comment period provides an opportunity for the public and agencies to review the DEIR and provide comments on the adequacy of the environmental analysis, impacts, and proposed mitigation measures.  

The MVSD Board of Trustees will consider and respond to all comments received during the public comment period in the Final EIR (FEIR). The FEIR will be a significant part of the record used to inform any project approval decisions on the locations for interim and permanent campus facilities. 

Addressing Historical Environmental Issues Responsibly

The Mill Valley Middle School property is going through a rigorous environmental review and cleanup process under the oversight of the California Dept. of Toxic Substances Control, Brownfields Restoration and School Evaluation Branch (DTSC).    

This branch of DTSC was founded to ensure that school properties that were previously contaminated – in this case from a municipal landfill that operated on the property from the 1900s to the 1950s – have been cleaned up or mitigated to a level that protects the students and staff who will occupy the new school.  

Through the environmental review process, DTSC ensures protection of children, staff and the environment from the potential effects of exposure to hazardous materials. As the only comprehensive school environmental evaluation program in the United States, the DTSC Brownfields Restoration and School Evaluation Branch continues to set the national standard.

Other schools that have gone through this process include most schools within the Los Angeles Unified School District and the San Francisco Unified School District, as well as several schools within the San Diego Unified School District.

Environmental Review Process

The middle school is located on the site of a former municipal landfill where waste was buried or burned from the 1900s until it closed in the 1950s.  Before the school was built in 1969, records indicate a cap of 2 to 3 feet of sandy clay was installed to prevent contact with underlying waste. Marin County Environmental Health Services (MCEHS) conducts quarterly inspections of the former landfill, which includes the redeveloped Community Center property, the middle school, and the Sewerage Agency to the south, to make sure that conditions remain protective of public health and the environment.

To make sure historical environmental issues are fully evaluated and addressed, MVSD is conducting a Preliminary Endangerment Assessment, or PEA, under the oversight of DTSC.

Environmental work will be conducted in two phases:

Phase 1 – Site Investigation (current phase): Conduct a site investigation, or PEA, to determine if the landfill waste left underneath the cap presents a potential risk to human health and the environment. This involves reviewing the site history, sampling soil, soil vapor (air in between soil particles) and groundwater, and evaluating potential ways that people and animals could be exposed to contamination. This information is used to determine the need for further investigation or mitigation actions. The PEA must be approved by DTSC before a response plan can be developed.

Phase 2 – Response Plan:  Prepare a response plan with specific methods to prevent, reduce, or control harmful environmental impacts.  Such methods may include state-of-the-art engineering controls.  

Upon approval of the PEA, a response plan will be prepared that outlines activities to address environmental conditions to support safe property redevelopment and reuse.  The response plan will be available for public review and comment.

PEA Preliminary Findings

The PEA Report findings indicate the current school campus is safe for students; however, there may be a slight increase in hypothetical cancer risk for staff based on one soil vapor sample (out of 7 collected) and an assumed exposure duration of 25 years. The analysis to determine potential health risks and outcomes is extremely conservative (health protective), as risk assessors and scientists are required to overestimate risk and err on the side of safety.

The report also found that cleanup or mitigation measures will be needed to provide long-term protection of public health and the environment if a new school is built on the current middle school campus.  This could include adding additional material to the cap and installing vapor mitigation systems under any new buildings which is exactly what was done at the Mill Valley Community Center. 

Public Input Process for DEIR and PEA and Schedule

The District encourages community involvement to ensure all voices are heard and concerns addressed.

We anticipate beginning the 45-day public comment period for both the DEIR and PEA in July and August 2025, with a public hearing held in mid-August.  

Both documents will be available online so they can be accessed remotely. The public hearing will be held in-person and will include an option to participate electronically. 

Anticipated Schedule