PFAS at Well 15
Madison Water Utility has detected low-level concentrations of PFAS chemicals at Well 15 on East Washington Ave. (located near Truax National Air Base). PFAS have been detected at high levels in shallow groundwater at Truax National Air Base, according to the DNR. The base sits just one mile from Well 15.
While water at Well 15 does not exceed any state or federal health-based drinking water standard, Madison Water Utility will not operate the well until the Wisconsin Department of Health Services (DHS) recommends groundwater standards for 34 types of PFAS, which it is currently investigating.
A type of PFAS compound called Perfluorohexanesulfonic Acid (PFHxS) has been detected in Well 15 at around 20-21 parts per trillion (ppt). Wisconsin DHS is working to determine a groundwater standard for for this compound. DHS has already recommended a standard for two other types found in Well 15, called PFOA and PFOS, of 20 ppt. Levels of PFOA and PFOS in Well 15 are below this recommended standard at around 12 ppt.
This groundwater study was initiated by Madison Water Utility to evaluate the time of travel for PFAS contamination from the Truax Air Field to Well 15 and update the Well 15 capture zones to determine if Truax could be the source of PFAS at Well 15.The study confirmed that Truax is inside Well 15’s groundwater capture zone. It also showed that the time of travel for groundwater from Truax to Well 15 is about 35 to 50 years. Based on the study, Madison Water Utility concluded that Truax Air Field is the likely source of low levels of PFAS detected at Well 15.