Madison Water Utility first discovered PFAS in two Madison wells in 2017 while conducting limited testing at wells near landfills and the airport. One of those wells – Well 15 located on East Washington Ave. – was shut down in 2019 amid community concerns about PFAS chemicals found there. The utility believes the chemicals detected in that well likely migrated from Truax Air Field, about a mile away.

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Well 15 Feasibility Study for PFAS Removal

The final report of the Well 15 feasibility study was completed April 8, 2021. It will be presented to the Water Quality Technical Advisory Committee and Water Utility Board in April.

Goals of the study:

  • Evaluate treatment technologies
  • Get a general estimate of upfront and ongoing costs for effective treatments
  • Provide a recommended treatment design that would:
    • Remove PFAS.
    • Remove PCE and TCE, eliminating the need for the air stripper system that’s currently set up at Well 15.
    • Allow 1000 gallons per minute of water to be produced from the well.

Study results:

A granular activated carbon system was the recommended treatment technology.

  • Granular activated carbon successfully removed PFAS, PCE, and TCE.
  • The estimated initial cost of the recommended system was $825,000.
    Note: This is a general estimate for the treatment system only. There would be additional costs to modify the building at Well 15 because it is not tall enough.
  • The estimated ongoing costs would depend on how frequently the carbon is replaced. The preliminary estimate was $50,000 to $300,000 a year.
  • The major components for the recommended system (ex: bag filter units, steel pipes, tank) have a life expectancy of approximately 30 years.

Read the full report:  Well 15 Feasibility Study for PFAS Removal: Bench-Scale Testing Report

What’s next?

Madison Water Utility will evaluate different alternatives to determine whether a treatment system at Well 15 is the best, most cost-effective option for meeting water supply needs on Madison’s east side.

Well 15 Testing

Madison Water Utility 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.

Well 15 Modeling & Groundwater Study report

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.