Mill Valley Middle School is about to swap summer quiet for heavy equipment. The campus is entering the construction phase of its $95 million modernization this month, with crews building an on-site interim campus and lining up portable classrooms the district expects to have in place this fall. A ribbon-cutting is set for 5 PM on June 18 at the school, and students are scheduled to move into the temporary campus while the main buildings undergo renovation over the next two years.
Timeline and what to expect
According to the Mill Valley School District, site preparation began Monday. Interim-campus construction is slated to run from June 15 through December 2026. Crews are expected to remove about 13,000 cubic yards of soil, pour concrete to raise the site grade, install utility trenches and complete foundation pours in August so portable classrooms can be placed later in the fall.
Students are anticipated to relocate to the interim campus in December 2026. Renovation work on the main campus is scheduled to start in January 2027, with officials planning to keep classes running throughout the shuffle.
The interim campus and modular plan
Flint Builders, the contractor on the project, describes a 29-building interim housing campus to be staged north of the existing school so instruction can continue while construction is underway. The modular layout is intended to let the district phase work across the site while keeping enough classrooms open for students.
The firm lists this modernization as the interim housing phase of a larger campus program, with the portable village serving as the bridge between the current setup and the future rebuilt middle school.
Site history and environmental oversight
The Draft Environmental Impact Report notes that the campus sits on a former municipal dump and burn site, and that a clay cover was added before the school was built. Recent testing found landfill material at shallow depths beneath portions of the property.
According to the EIR and state review records, agencies, including the Department of Toxic Substances Control and the Regional Water Quality Control Board, have been overseeing the project. That oversight required a Preliminary Endangerment Assessment along with mitigation measures aimed at keeping the work safe for students, staff and neighbors.
Plans call for engineered barriers, methane monitoring, continuous air sampling during soil work and a soil-management plan to guide excavation and disposal. The goal is to let crews dig, haul and rebuild while tracking what comes out of the ground and where it goes.
Traffic, parking and early-morning deliveries
Construction on a tight neighborhood campus usually means traffic headaches, and the district is trying to get ahead of that. To limit disruption, officials say they have secured additional staff parking at Mt. Tamalpais United Methodist Church and will shuttle contractors from off-site parking at Terra Marin School. Truck traffic is set to follow a designated route through East Blithedale and Camino Alto.
Noisy activities are generally limited to 7 AM to 5 PM. Some work, including concrete pours and portable deliveries, will happen outside those hours with advance notice to neighbors. The district is posting weekly construction updates and operating a project hotline for parents and nearby residents who want details beyond the orange cones and fencing.
What comes next
District officials say the interim campus is designed to keep teaching and learning steady while the renovation moves forward. Community briefings and weekly emails are planned to walk families and neighbors through mitigation steps and timing as dates are confirmed.
Marin Independent Journal first reported many of the timing details and notes that the June 18 ribbon-cutting will be held at 5 PM, when officials expect to walk neighbors through the construction schedule and safety plans in person. Parents can sign up for the district’s construction emails or call the hotline to stay on top of the latest notices.
