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Zone 7 Water Agency plans to drill new wells in southwest Pleasanton near the leading edge of an enormous plume of PFAS, a.k.a. “forever chemicals”, underlying the Tri-Valley. And they’re pushing Pleasanton to join them.
New groundwater modeling commissioned by Zone 7 appears to be very accurate in predicting groundwater levels based on historical data, but this is not the same as predicting PFAS plume movement. The model doesn’t show how the PFAS plume grew from nothing 50 or 60 years ago (from recently confirmed sources) to its current titanic size: six miles long and two miles wide.
A model that can’t reproduce the historical plume movement is not useful in predicting future plume movement. This plume is now within a couple tenths of a mile from the proposed well locations, so the risk of further spreading, especially with increased pumping, is substantial. In fact, PFAS has already been detected at the proposed Hansen Park well site.
Yet Zone 7 continues to assert that the new wells will be PFAS free for at least 20 years. Zone 7 previously claimed there were faults or other geologic barriers that would prevent PFAS from moving to the proposed locations. However, at a recent public meeting, Zone 7’s own consultant indicated that there are no significant barriers.
This recent turnabout casts doubts on Zone 7’s credibility regarding PFAS plume movement predictions.
Why would Zone 7 minimize the risk of spreading PFAS to the proposed new wells? Are they stuck on a 20-year-old plan for new wells developed before PFAS was known to be a problem? Have they run out of ideas for new sources of water?
They say that if PFAS is found in the new wells, then they’ll treat the water to remove it, but at what cost?
Water is essential to life and society needs water to thrive. So how can this need be met here, especially in times of drought? The big push for new wells came because old wells were shut down due to high PFAS concentrations.
To their credit, Zone 7 is treating water from their old wells to remove PFAS, and they plan to treat additional wells as their budget allows. Pleasanton’s old wells were also shut down due to PFAS, but they have no plans to treat that water.
Zone 7 is adept at treating water; Pleasanton is not. Pleasanton has stated that they don’t want to be in the water treatment business. But Pleasanton’s well locations are in the heart of our groundwater basin and capable of producing all the water sought by installing the proposed new wells.
Pleasanton and Zone 7 should work together to produce water from Pleasanton’s well locations for the good of current and future Tri-Valley residents.
Pleasanton has the rights and Zone 7 has the expertise to treat the water. This would go a long way to control and shrink the PFAS plume, remove PFAS from our groundwater basin and produce clean drinking water when needed, as in times of drought. This is the type of agreement Pleasanton and Zone 7 should be working on, not plans that would risk spreading the plume and making the ultimate cost of cleanup even greater.
This is not a new idea. Pleasanton originally planned to treat their wells when PFAS was discovered there but was convinced by Zone 7 that drilling new wells in southwest Pleasanton would cost less. Yes, maybe cheaper in the short term, but more than likely much more costly in the long term.
Editor’s note: Jim Lehrman, a resident of Pleasanton since 1988, is a professional geologist and certified hydrogeologist licensed by the state of California.
