Above left, a simulated image of a current PFC plume affecting local water pumping conditions. The top of the plume reaches toward two red dots, which mark Sammamish Plateau Water wells nos. 7 and 8. Above right, a simulated image of the PFC plume’s possible future conditions, factoring 50 percent reduced pumping at wells nos. 7 and 8 (images courtesy of Sammamish Plateau Water).

Above left, a simulated image of a current PFC plume affecting local water pumping conditions. The top of the plume reaches toward two red dots, which mark Sammamish Plateau Water wells nos. 7 and 8. Above right, a simulated image of the PFC plume’s possible future conditions, factoring 50 percent reduced pumping at wells nos. 7 and 8 (images courtesy of Sammamish Plateau Water).

Sammamish Plateau Water update shows contamination threat low, though concerns remain

In an update on local water issues concerning chemical compounds such as perfluorinated compounds, or PFCs, and perfluorooctane sulfonate, or PFOS, Sammamish Plateau Water general manager Jay Krauss shared with the Sammamish City Council Tuesday that while there was a very low risk to the local water supply, the water district was not without reasons to be concerned from its water monitoring results.

“Based upon our current production practices and what we know, there’s very low risk to the groundwater supply right now,” Krauss told the council during a presentation. “That can change though. It’s a slow-moving train.”

The three wells of focus regarding the water quality issues were district wells nos. 7, 8 and 9, all located in the lower Issaquah valley. Of the district’s 1.7 billion gallons of water produced to the plateau, 38 percent, or 661 million gallons of water, comes from those wells.

Krauss said the district was first required to conduct additional water testing in 2015 under the Environmental Protection Agency’s Unregulated Contaminant Monitoring Rule program. Results initially came back below lab detection levels, Krauss said, though continued tests later showed a trace amount of contaminants in well no. 8.

Krauss said the water district began working with a consultant and has tested its wells monthly when the wells are in production. He noted contaminants have been found in local surface water. In continuing to test the district’s well no. 9, he said the district detected trace amounts of contaminants in the well.

Contaminants have also been found in soil samples at the Eastside Fire and Rescue headquarters, which is located south of the wells.

“While Eastside Fire and Rescue headquarters may be considered a likely source of the contamination, our consultants feel there may be other sources, too, even though [Eastside Fire and Rescue] appears to be a primary source,” Krauss said. “There may be another source of release in the lower Issaquah valley.”

Krauss commented on the complexity of groundwater modeling, stating there are “significant unknowns as to what’s really going on below the ground” due to what can’t be seen. He said the district has seen the general flow of groundwater following the area’s topography and flowing from south to north, generally leading to Lake Sammamish.

He said the district learned in working with a technical consultant of a likely plume and the likely migration of contaminants based upon a suspected release at the Eastside Fire and Rescue headquarters. Krauss presented the council with two of 12 simulated groundwater scenarios run by the district, which he said the district was using in trying to understand further impacts to wells nos. 7, 8 and 9, as well as to minimize those impacts.

A graphic showing a present day simulation of the plume’s likely impact to the wells showed no impact to well no. 9, though it showed fringe impacts to wells nos. 7 and 8. Later on in his presentation, Krauss said in monitoring another well, well no. 6, the district has also found increased levels of PFCs.

Krauss said actions being considered to minimize the impacts included reduced pumping from the affected wells to combat the plume’s migration. Moving forward, he said a monitoring and testing plan that was being developed by a second consultant will provide further insight to the district’s board of commissioners on appropriate next steps.

Krauss called the water issues “a tri-party issue,” noting the water district shares the aquifer with the city of Issaquah, and also mentioned the possible role Eastside Fire and Rescue plays in the matter. He said it was important for all parties involved to engage and share the same interest in solving the water issues.

“Kind of the challenge for everyone is these are are health advisory limits on a compound that’s not regulated by the EPA or the state of Washington. It’s almost like chasing your shadow; you know that there’s something there, but even if [Eastside Fire and Rescue] found out they were a source and they wanted to mitigate it somehow or mediate, no one is citing any levels to help their response,” Krauss said. “There will continue to be data that’s found.

“Unfortunately, some of these things can appear to be slow-moving but it’s the nature of environmental analysis … I would guess 2-3 years from now, we’ll have a different data set than we have today. We need to be diligent,” he said.


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