Consultants from Geosyntec Consultants, the Seattle-based firm that has been studying Perfluorooctane Sulfonate (PFOS) levels in Issaquah water, believe that Eastside Fire and Rescue may be a source of the PFOS.
Bob Anderson of Geosyntec gave the Issaquah City Council an update on the city’s ongoing water investigation at the Sept. 19 meeting.
In early March, the city shut down Gilman Well No. 4 after finding PFOS in the water. The council voted to install a filtration system in April, a decision that proved successful; there has not been any PFOS detected in the filtered water, and the well has since gone back online.
Since then, the city and Geosyntec have been diligently testing the water for contaminants and trying to discover the source of the toxins. In July, Geosyntec approached Eastside Fire and Rescue about testing its soil for PFOS. Eastside Fire and Rescue’s headquarters at 175 Newport Way NW are located in the same general area in which the contaminants appear to be originating, Anderson said.
Three soil samples were taken on Eastside Fire and Rescue’s property. On Sept. 8, the city announced that PFOS had been found in all three samples.
“We do think that this is at least a source [of PFOS],” Anderson said.
PFOS is part of a family of chemicals known as perfluorinated compounds (PFCs). PFCs are used in the production of fire suppressants, Teflon and waterproof clothing like Gore-Tex.
“Firefighting foams are a known source of these perfluorinated compounds,” Anderson said.
The highest level of PFOS found at Eastside Fire and Rescue was 1.3 milligrams per kilogram.
“It’s not what you might call screaming hot, but there is definitely presence of perfluorinated compounds in the soil,” Anderson said.
Consultants hypothesize that a narrow plume of PFOS has originated somewhere south of Monitoring Well No. 5 at the Salmon Run Nature Park and west of Issaquah Creek, and traveled north in the groundwater. This would fit, Anderson said, as the land slopes downward the further north you go. This would also explain why trace amounts of PFOS were found to the north at Sammamish Plateau Water Wells No. 7 and 8, which share the Lower Issaquah Valley Aquifer with Issaquah’s Well No. 4.
Anderson said consultants do not believe that the response to the I-90 tanker fire in 2002 is a source of the PFCs.
The consultants are recommending a “more comprehensive” soil investigation on the Eastside Fire and Rescue property, according to Anderson. They also suggest installing wells downgradient and upgradient of the property to detect if any PFOS is moving downhill from the firefighting headquarters.
Anderson said the consultants plan to continue monitoring the wells and searching for other potential sources of PFOS.
“We need to nail down where the most likely source is,” Anderson said.
Councilmember Mary Lou Pauly asked Anderson if the 1.3 milligrams per kilogram measurement was considered to be a high level of PFOS in the soil, and if firefighters at Eastside Fire and Rescue who may be exposed to the soil are in danger.
Anderson said that the Environmental Protection Agency’s standards for contact and ingestion of PFOS are around 6 milligrams per kilogram, and that “based on that one sample,” there is no risk to firefighters.
In high amounts, PFCs have been linked to a variety of health issues, such as cancer, thyroid problems, a weakened immune system, high cholesterol and pregnancy complications such as preeclampsia.