Dangerous

Updated with New Soil Sample Results - April 2025

On April 8, 2025, the District released its draft Preliminary Endangerment Assessment (“PEA”), presenting data from soil samples collected in Fall 2024. The PEA evaluates two scenarios:

  1. Current site conditions with the protective soil cap intact, and

  2. Future site conditions if the soil cap were compromised, exposing hypothetical residential users to contaminated soil, groundwater, and vapors.

Many of us have children attending MVMS, so we are glad the current site conditions are considered safe. The recent article in the Marin IJ focused solely on the site’s present-day safety. However, that has never been our primary concern.

Our concern is what happens when construction inevitably breaches the protective soil cap—unleashing a Pandora’s box of contaminants—while our children breathe and learn next door.

For that reason, we are focusing on the second scenario: the risks posed if the soil cap is disrupted, as that is what is relevant during construction. Here are the key findings from the recent soil tests:

Extent of Toxic Waste

  • The site is a former burn dump (EPA ID: CAN000905996).

  • The hazardous waste extends across the entire site (PEA, p. 37).

Lead

Safe Screening Level

  •  80 mg/kg is the screening level for lead. Anything over that is potentially hazardous (PEA, p. 45). 

 We Knew it Would be Bad

  •  The Community Center’s 2003 soil tests listed lead levels at 6,500 mg/kg (p. 4). That’s already 81 times the allowable level.

But the MVMS Results are Way Worse 

  •  37 soil samples had elevated lead, ranging from 92 mg/kg to 23,000 mg/kg (PEA, p. 45).  Yes, you read that right. 23,000!!! That is up to 288 times the allowable level.

Arsenic

Safe Screening Level

  •  0.0082 μg/L is the screening level for arsenic. Anything over that is potentially hazardous.

Groundwater Results Shockingly High

  • “Arsenic was detected in all of the grab-groundwater samples at concentrations ranging from 11 μg/L in GW-1 to 190 μg/L in GW-4.” (PEA, p. 28).  That is up to 23,171 times the allowable level.

Methane

Safe Screening Level

  • The lower explosive limit for methane is 5% and the upper explosive limit is 15% (PEA, p. 32).

Methane Greatly Exceeded the Upper Explosive Limit

  • Methane was detected in all soil vapor samples except for one, at concentrations ranging from 0.0051% to 77% (PEA, p. 32). 77% is up to 5 times higher than the upper explosive limit of 15%. The alarming 77% reading came from the East side of campus (PEA, p. 40), where the District plans to install the temporary campus.

Methane Explosions from Landfill Gas Happen

  • 8-year-old burned by methane gas explosion under playground

Other Contaminants of Potential Concern

  • Alphabet Soup. “The analytical results indicate that [contaminants of potential concern] in soil include antimony, arsenic, cadmium, hexavalent chromium, cobalt, copper, lead, mercury, thallium, zinc, TPHg, TPHd, benzo(b)fluoranthene, BaP, indeno(1,2,3-cd)pyrene, dibenz(a,h)anthracene, and dioxins. COPCs in groundwater and surface water include arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, nickel, mercury, vanadium, zinc, TPHg, and TPHd. [Contaminants of potential concern] in soil vapor include PCE, TCE, vinyl chloride, chloroform, and methane.” (PEA, p. 36-37).

  • Hexavalent Chromium.  The PEA analyzed samples to differentiate between trivalent and hexavalent chromium. Of the 21 samples analyzed, 7 had detections above the Department of Toxic Substances Control screening level for hexavalent chromium. “Hexavalent chromium is a more toxic form of chromium” (PEA, p. 25).

  • PEA Table 4-1 (below) summarizes the concerning metals. The “SL” column refers to the “screening level,” which is the relevant safety threshold. All of the measured levels greatly exceed the applicable screening level.

Human Health Risk Assessment

  • Cancer and Health Risk.  “Exposure to maximum concentrations of [contaminants of potential concern] detected in soil within the landfill waste could, if not mitigated, pose a cancer risk and/or health hazard to the hypothetical residential receptor” (PEA, p. 70). The hypothetical receptors here are students and staff present during construction.

  • Quantifying the Risk.  The PEA health assessment culminates in a Hazard Index number. The greater the number is above 1, the greater the potential hazard (PEA, p. 55).

    • The current site’s risk, with the soil cap securely in place, is 0.1 for staff and 0.2 for students, which as noted, is safe.

    • But what about our uncapped scenario? That figure leaps up to 60!  That is, of course, 60 times higher than the safe level of 1 (PEA, p. 55).

Common Sense Advisable, Even with the Current Soil Cap

Even though current conditions at the site are safe, please use common sense when interacting with any water present on campus:

  • Keep your children out of the creek that runs through campus. It is fenced off for a reason, so please make sure your children know not to climb that fence to explore.

  • Avoid dermal contact with any floodwater on campus. If your children must wade through water to get to class during a King Tide, send them with high rubber boots and warn them not to jump or splash in the water.

Why this note of caution?

  • Landfill waste is already surfacing in the Creek. That is why it is fenced off. In March 2024, CalRecyle issued a Notice of Violation to the District, observing: “Old landfill waste was observed in basin and along the banks of the drainage south of the portable classrooms…Site is not being maintained in a manner which protects public health and safety or prevents public contact with waste. Waste drainage is readily accessible to the public. Need to restrict access to the location of the waste with a physical barrier.” The District enhanced the fencing around the creek in response. Images of the surfacing waste are below.

  • Surface water at the site contains elevated lead. One reading registered 22-μg/L, which exceeds the surface water lead screening level of 10 μg/L (PEA 31).

  • Groundwater at the site also contains elevated lead, which can surface during flooding. Lead was detected in all of the grab-groundwater samples at concentrations ranging from 30 μg/L to 5,300 μg/L, all of which exceeds the groundwater lead safety level of 10 μg/L (PEA, p. 29).

Photo Taken October 18, 2024: Note that this is the creek that the County required the District to fence off to prevent people from having any contact with the water that is known to be contaminated from the landfill (see above letter from County about this). At high tide, in the dry season of October, the water is already seeping past the fence, so kids could puddle-jump in this water. Note as well that this is another lovely view of the proposed temporary campus, with its toxic creek and nearby high voltage power station.

  • Contaminated Burn Dump

  • Extremely High Lead Levels

  • Potentially Explosive Gasses

Site Recap:

With all of these concerns, there is a clear need for robust mitigation plans.  The PEA reaches that same conclusion. Unfortunately, mitigation plans were not carefully considered before the School Board narrowed in on the current site plan.