Foam That Roams

How to tell if your well is at risk of wandering PFAS

The West Plains are at the edge of the Columbia River Basalts, layers of lava that
flowed from Washington’s southeast corner 15-17 million years ago, covering most of
Eastern Washington and Eastern Oregon, oozing all the way down the Columbia to the
Pacific. The northward advance of these flows ended at the West Plains, where their
edges then eroded into channels draining north and east to the Spokane River. Much
more recently, gigantic ice-age floods filled all these channels with sand and gravel,
creating the nearly flat West Plains we know today. We cannot see the old ravines in the
now-buried basalt, but they are still there.

This is important because PFAS pollution from Fairchild AFB and Spokane International
Airport is slowly moving in groundwater through gravels down these buried
“paleochannels”. Exactly where it flows is still under study. However, well tests suggest
that paleochannels often make the difference between a clean well and a contaminated
one.

This is actually good news for most, as around 75% of West Plains well tests to date
show little or no PFAS contamination. This roughly corresponds to the 75% of the area
in our West Plains aquifer that is thought to lie outside the paleochannels.

Within the paleochannels it’s a different story, with high PFAS concentrations often
appearing—even several miles from Fairchild and the airport, down drainages such as
Deep Creek.

So how do you know if you’re in one of these paleochannels? Look for clues in the
landscape:

• Most West Plains commercial gravel pits are in paleochannels, because they are where the gravel is, so if you live near a gravel pit your well may be at more risk of contamination.
• Denser forests and more fertile farms are often found in paleochannels, due to deeper soils.
• You may be outside the paleochannels if you see signs of near-surface bedrock on your property: rock outcrops, surface ponds, stunted trees, or wire fences anchored with above-ground rock cribs rather than deeply driven fenceposts.

The only sure way to know if your well is clean is to have it tested, of course.

When you test, please email the results to the West Plains Water Coalition to add to our
map, so we can better understand where toxins are and how to deal with them. To
protect your privacy, your address will not be shown.