Mill Valley trustees narrow middle-school options after steep soil-disposal costs; approve further geotechnical work

Mill Valley School District trustees on Aug. 14 reviewed updated environmental and budget analyses for the Mill Valley Middle School modernization and approved agreements for further geotechnical, hazardous-material and surveying services to inform a December decision on a preferred alternative.

Superintendent Dr. Kaufman told the board the district’s environmental review has revealed geotechnical conditions that greatly increase costs if full deep soil mixing (DSM) and off‑site spoil disposal are required, citing analyses that raised earlier hard‑cost estimates by tens of millions of dollars. Staff said the soil work and disposal volume—discussed in the meeting as roughly 56,000 cubic yards of spoils in the most intensive scenarios—drove the board to narrow options to two alternatives that will be evaluated in the draft EIR: (1) a value‑engineered renovation of the existing Mill Valley Middle School with a $95 million hard‑cost budget that holds potential soil‑mitigation funds outside that core budget, and (2) building a new campus at 70 Lomita (the Terramarine/Aetna site).

Kaufman said the $95 million renovation approach was intended to avoid adding long‑term financing costs and to remain below the district’s 50 percent replacement‑value threshold so the district would not be required to perform a full structural replacement. He said the draft EIR will analyze both options and that staff plans a public comment period after the draft EIR is released Sept. 2 (staff stated the public-comment window would run to Oct. 16). The board was told staff hopes to certify a final EIR and select the preferred alternative at a special meeting in early December so construction or interim‑housing actions could begin in 2026 depending on the option chosen.

During a technical exchange, Bill Anders, a structural engineer, explained why updated subsurface testing showed bay mud and layers susceptible to liquefaction and lateral spreading in an earthquake, and why deep soil mixing would be a likely ground‑improvement response. Anders described DSM as overlapping treated columns of soil and grout that yield spoils that may require special (sometimes out‑of‑state) disposal if classified by environmental agencies, a factor that materially increases project costs.

Trustees pressed staff on financing assumptions, contingency levels and potential state modernization funding; staff said the district is conservatively holding contingencies and that applications to state programs could yield roughly $24 million if fully realized, though that timing and amount were not guaranteed. Staff told the board that portables are in high demand and that delivery timelines make interim‑housing options (if needed) likely to occur in late 2026.

Two members of the public urged support for renovating the existing campus. Doug Nelson said the current campus offers walkability and programmatic benefits and raised concerns about certain proposed shade-canopy design elements; Stephanie Meservi praised the superintendent and staff for their work and urged trustees to follow expert guidance.

The board voted to authorize three contracts to support the next phase of analysis: a geotechnical services agreement with Nino & Moore, hazardous‑materials services with SCA Environmental (for PEA/HAZMAT sampling and analysis), and a surveying contract (names and exact contract language were read into the record during the meeting). Each motion was moved and seconded and approved by voice vote with multiple trustees saying “Aye.”

Sandrine (staff) reported a PEA update: DTSC (Department of Toxic Substances Control) and Marin County Department of Environmental Health had reviewed agency comments, additional sampling occurred in July and agency comments with district responses will be included in the draft EIR; revised PEA materials were expected for public comment in October. Kaufman asked trustees to reserve substantial time at the Sept. 10 meeting for public input on the draft EIR.

Next steps: staff will release the draft EIR on Sept. 2, host a public‑comment window through Oct. 16, present public comment at the district’s Sept. 10 board meeting and seek certification/selection of an alternative in early December. If the board selects interim housing, staff said portables installation could occur in October 2026; full construction timelines would vary by alternative and could lead to occupancy after winter break in January 2029 under a full rebuild schedule.

Actions taken at the Aug. 14 meeting are limited to contracting for further studies and do not select a final project. The board will return in September and December with technical findings, public input and a staff recommendation to guide its decision.