Dangerous
The site is a former burn dump with elevated toxic substances
MVMS and the proposed temporary site sit on top of a former burn dump, classified as a Superfund site (EPA ID: CAN000905996). Superfund sites are locations polluted with hazardous materials. The toxic materials are covered by a clay soil cap, but the proposed construction will inevitably disrupt that cap.
Even if the cap is eventually restored, students and staff on-site in the meantime could be exposed to toxic substances with lifelong consequences. Now is the time to prevent this harm by coming up with an alternative plan for the temporary site.
“Wait, what?!” - Yes, seriously. You don’t have to take our word for it. Here are the primary source documents and supporting data:
Site History: “[T]he Site was used as a burn dump…and was reportedly closed in the 1950’s. The dump operated for approximately 40 years and received household waste. The refuse was burned along the west side of a canal and north of Sycamore Avenue. After burning the refuse was spread as fill over the rest of the site and was reportedly covered by a two- to three-foot soil cap (sandy clay soil)…Mill Valley Middle School was constructed on the Site in 1969. Previous limited environmental investigations at the Site found elevated concentrations of metals (copper, lead, and zinc) and total petroleum hydrocarbons.”
Source: Environmental Oversight Agreement between MVSD and the California Department of Toxic Substances Control (DTSC), dated April 27, 2024 (Section 2.4)
The dump accepted “household waste”, but given scant environmental oversight during this period, this could have included mercury from thermometers, oil and gas, lead paint, car batteries and other auto parts, appliances, toxic cleaners, etc. No one really knows!
Marin County Environmental Health Services sent the District a letter, dated August 5, 2024, which advises, “Radiation monitoring should be performed as radioactive waste has been found at other burn dump sites.”
UPDATE - Potential Radiation Hazard
Lead level in buried soil is 81 times higher than allowed residential level
The Department of Toxic Substances and Control last took soil samples at the site in 2003. The 2003 Report identified various contaminants (copper, zinc, phenanthrene, and petroleum hydrocarbons), but the most concerning were the high amounts of lead, measured at 6500 mg/kg. Note, the soil containing elevated levels of metals is buried 7 5 to 13 5 feet bgs with fill, buildings, or parking lots above the contamination, so it is presently contained. Construction, however, could easily dredge it up.
Source: EPA’s Preliminary Assessment Report, dated March 25, 2003 (Section 2.4.3 and 3.1)
For context, the California Department of Toxic Substances Control (DTSE) advises, “Soils with a total lead concentration of 500 mg/kg or less are usually considered acceptable for use at commercial/industrial properties with prior written approval from DTSE, but land use restrictions are required to prevent unacceptable risk by limiting the use of the property.” The threshold for residential use is a mere 80 mg/kg.
Potential Toxic Effects of Lead Exposure
“Acute exposure to lead results in: encephalopathy, characterized by headache, drowsiness, and in higher doses by coma, convulsions, or even death. Recovery from acute lead encephalopathy often results in residual neuropsychologic impairment, characterized by reduction in intelligence and behavior changes.
“Chronic lead toxicity affects the red blood cells and their precursors, the central and peripheral nervous system, and the kidneys. Studies have also indicated an adverse effect on reproduction in both males and females from chronic lead exposure. “
Sample Lead Mitigation Measures for Workers
“Although 9 of the 13 Priority Pollutant Metals were at various ranges of concentrations across the site, the levels of most concern were for lead. The lead concentrations ranged from 11 to 6,500 ppm. The elevated concentrations exceed the Department of Health Services (DHS) Hazardous Waste Total Threshold Limit Concentrations (TTLC).”
“Although there is a 2 to 3 foot capping layer over the soil containing the toxic debris at the site, excavation for proposed utilities and/or subsurface vaults will probably extend into the debris-laden soil. Soil containing debris that is excavated during construction will need to be handled as a hazardous waste. The workers performing grading operations including the handling of these toxic materials will be required to have the proper training…In addition, dust mitigation will be required to prevent the migration of toxic materials in the air.”
Combustible landfill gas
“Due to the buried landfill materials, generation of landfill gases (i.e. methane, hydrogen sulfide) seems likely to be released to air. Several times, (1982, 1988, 1995) the site has been tested for combustible gases. In 1982, the east side of the MVMS (the only part of the building suspected to be above the buried debris) was tested with no gases detected… In 1995 samples were taken from five monitoring wells, only one of which had any detection of combustible gases (Hydrogen sulfide, carbon monoxide, combustible gases). The new Mill Valley Community Center (built between 1999-2001) has a built in monitoring detection system. In addition, during the building footprint excavations, a geotextile membrane was placed upon the soil below the foundation. The soil gas releases are seasonal and dependent on high groundwater level at the site. Detectable releases during the winter (rainy season) in initial testing were reported.”
Source: EPA’s Preliminary Assessment Report, Mill Valley Community Center, dated March 25, 2003 (Section 3.4)
Note: The proposed temporary campus is on the East side of MVMS and will include the gymnasium, which the 2003 EPA Report states are the only parts of the site directly above the buried debris, which puts it at the highest risk for combustible gasses and toxic substance exposure. The landfill gasses will need to be capped, mitigated, and actively monitored, just as they are at the Community Center. Perhaps that’s acceptable once those systems are in place, but having our children on-site during excavations into this landfill, with its stored explosive gasses, is a serious concern.
“A previous Hydrogeologic Investigation at the site by GeoResource Consultants concludes that elevated levels of landfill gas (LFG), including hydrogen sulfide, carbon monoxide and combustible gasses are present in the fill and the underlying Bay Mud. Consequently, during design it will be necessary to provide appropriate LFG collection and burial systems beneath planned improvements.
Source: Geotechnical Investigation Report, Mill Valley Dump Site, dated May 10, 1995, prepared by Herzog Geotechnical
Landfill gas explosions are serious and unpredictable
Recent MVSD Notice of Violation
Notice of Violation: CalRecycle issued a Notice of Violation to MVSD on March 18th, 2024, providing, “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 matter was also referred to the Regional Water Board due to potential impact to water quality. The Notice included images of the contamination, shown here. Note proximity to proposed temporary campus.
Source: County of Marin (CalRecycle) Notice of Violation, March 18, 2024.
Burn Dump with Potential Radiation
Extremely High Lead in Soil
Potentially Explosive Gasses
Recent Safety Violations