After a protracted discussion, the City Council voted unanimously April 4 to spend $988,000 to mitigate contamination problems with Issaquah water system’s Gilman Well No. 4.
The amount was slightly less than the $1.08 million requested by the administration in its most recent agenda bill. The council previously had approved $150,000 to partially pay for a filtering system for Well No. 4.
Since potential problems with the chemical perfluorooctane sulfonate — known more commonly as PFOS — first became public in January, the Issaquah administration has contended the city’s drinking water is safe, that PFOS-contaminated water is blended with water from other wells and meets all standards by the time it reaches the tap.
In water straight from Well No. 4, PFOS levels have registered as high as 0.6 parts per billion, three times the Environmental Protection Agency’s provisional health advisory level for the contaminant.
Consultants hired by the city and others said April 4 the EPA could lower the advisory level, meaning Well No. 4 could be in even more trouble.
As of Monday, the city had simply turned off Wells 4 and 5, which share a pumphouse. At first city officials said suspending use of Well No. 4 could cause problems with Well No. 5, which has not shown any PFOS contamination. The city then decided to take both Wells 4 and 5 offline.
On April 4, Robert Anderson of Geosyntec Consultants of Seattle said initial studies showed there is a risk of the PFOS contamination migrating from Well No. 4.
City staff members previously unveiled a filtering system to remove PFOS from Well No. 4. The city will lease two filtering vessels and install them outside the pumphouse that sits alongside Issaquah Creek as it flows under Interstate 90.
Even as they introduced the filtering plan, city staff members were upfront that $150,000 would not cover the full cost of the system. Including replacing the carbon filtering material, the initial costs were placed April 4 at about $658,000 for 2016.
Other costs laid out by the administration included further hydrogeologic studies, monitoring of the well network, water testing and other similar items adding up to a cost of $580,000.
Consultants said one ongoing problem with solving the PFOS problem permanently is they still don’t know for sure the source of the contamination. Many assumed it was the result of a large tanker truck fire on Interstate 90 in 2002. At the time, PFOS was commonly used in firefighting foam, and hundreds of gallons of firefighting foam was used to combat the truck fire. Anderson said he doesn’t rule out the fire being the source of the PFOS, but he’s not convinced that is the case.
While the council had plenty of questions, it ended up approving the administration’s requested funding except for about $100,000 members didn’t believe belonged in a request funding mostly short-term solutions.
Anderson said further study was probably needed before a final, long-term decision is made. Consultants want to drill several monitoring wells and return to the administration and the council with more information once it is available. Testing may take several months, consultants warned.