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A city consultant recently discovered PFAS chemicals in the soil and groundwater of the Livermore Municipal Airport, spurring the regional water board to call for additional evaluation of the site.
The PFAS investigation report published Oct. 13 by Geosyntec Consultants, Inc. was meant to determine whether PFAS — an abbreviation for perfluoroalkyl and polyfluoroalkyl substances — have been released at the airport and whether a discharge has contributed to PFAS plumes in the Livermore Valley Main Basin or contamination in municipal drinking water supply wells operated by the Zone 7 Water Agency.
Although PFAS are commonly detected in soil and groundwater, including in areas without known PFAS releases, the city must submit an additional investigative work plan by Feb. 2, 2026 in part to “define the extent of the groundwater contamination plume”, Executive Officer Eileen White of the San Francisco Bay Regional Water Quality Control Board wrote Oct. 27 to Livermore City Manager Marianna Burch.
The contamination threatens to pollute state waters as well as adversely affect human health and or groundwater uses, senior water resources control engineer Katie Kulha of the regional water board wrote Oct. 17 in a standard letter to Burch.
“We are still investigating the contamination at the airport,” water resources control engineer Kimberlee West of the regional water board told Livermore Vine. “We need to better understand the contamination before we can determine next steps, which may include abatement and remediation.”
During the investigation by Geosyntec from July to August 2025, 14 airport locations were sampled to assess for potential PFAS in areas of interest such as the runway, aircraft hangars and five rivers fuel farm, the report states.
Four newly installed groundwater monitoring wells were also assessed for potential PFAS migration onto and off of the site.
In all groundwater samples, the chemical mixture of PFAS exceeded permissible concentration levels, referred to as the hazard index maximum contaminant level, White recounted in her letter to the city. Individual PFAS were also detected at concentrations above permissible levels in various locations.
Failure to meet water quality standards means the groundwater “may be unsuitable for drinking without treatment”, West explained.
However, groundwater is treated before it is distributed as drinking water, West said. As such, all water supplied by public water agencies in the Tri-Valley meets the regulatory water quality standards set by the state and federal governments — typically the quality is significantly better than required, she added.
In the airport groundwater, the highest PFAS concentrations detected were located hydraulically downgradient of the south hangar area, the report states.
One kind of “forever chemical” called PFOS was found at an estimated concentration of 3,100 nanograms per liter, many multiples in excess of the 4.0 nanograms per liter maximum contaminant level for PFOS set by the U.S. Environmental Protection Agency.
A known release of aqueous film-forming foam for fire suppression in 1990 at hangar S-1 may have contributed to the PFAS concentrations observed in the groundwater in the area, according to White.
Additionally, groundwater in the runway area was found to contain elevated concentrations of PFAS breakdown products, White said in her letter. The chemicals are common transformation products of a type of aqueous film-forming foam, indicating that the foam may have been released near or upgradient of the runways.
Currently, aqueous film-forming foam is not stored at the site, the report states.
Soil samples from the airport contained PFAS amounts generally consistent with “background” levels, meaning concentrations that are generally detected in the environment without relation to the specific site under investigation, according to the report.
But in soil from the south hangar area, a type of PFAS called PFOA was found to exceed environmental screening levels for construction worker direct exposure — sites of excess may pose a chemical threat and further investigation or evaluation should be considered to better assess the threat, according to the EPA.
Notably, several surficial soil samples were collected below asphalt and concrete slabs, which serve as a barrier to human exposure.
Even at concentrations less than environmental screening levels PFAS detected in soil may indicate a surface release, White wrote in her letter.
The report suggests that PFAS in the airport soil may have come from sources such as aerial deposition and other activities that have not been identified, the report states.
As part of the Geosyntec report, the company recommended further evaluating the presence of PFAS at the airport including additional groundwater, grabwater and soil sampling to evaluate chemical concentrations.
Staff of the regional water board will be overseeing the investigation of the airport and potential clean up of the site.
Based on the regional water board’s average billing rate, oversight is estimated to cost the city $28,200 through June 2026, according to Kulha. The actual price will depend on the nature and extent of the necessary oversight.
