Date
Monday, September 9, 2024
Time
2:00 PM - 2:30 PM
Location Name
M111
Name
Florida Town Becomes Part of First AFFF Bellwether Trial From PFAS Elimination
Track
Drinking Water Treatment
Description

PFAS contamination of drinking water supplies has become a national focus for regulatory action. In May 2016, the EPA issued a health advisory lowering the admissible levels of PFAS (PFOA/PFOS) in drinking water to 70 parts per trillion (ppt). The City of Stuart, Florida, had their wells tested and realized a critical issue in their water system. Of the 23 wells serving its 19,000 customers, several were found to exceed this new limit with levels greater than 300 ppt. These levels are primarily attributed to the fire-suppressant foam (AFFF), used in firefighter training until 2002, containing PFOS. The City is currently part of the first AFFF bellwether trial, begun in June 2023. Prior to 2016, PFOS levels of 200 ppt and PFOA levels of 400 ppt were considered acceptable. The new advisory resulted in wells being taken out of service and further action to mitigate the contamination. Although the well shutdown reduced levels down below 70 ppt, levels were still higher than desired (>40 ppt) and the City wanted to do more and prepare for further reductions in allowable levels of PFOS and PFOA. Beyond the fire-fighting foam, there were potential impacts from other sources including an un-lined landfill, several industrial activities with other historical contaminations, a nearby airport, and groundwater recharge by wastewater reclaim that could infiltrate the water supply. A 4.0 MGD (2,800 gpm) capacity IX treatment plant, partially funded by State revolving loans and grants, was constructed and brought online in spring of 2019. Stuart uniquely trialed four different resins initially, one in each vessel, and then tested their effectiveness to determine the most effective resin for their water supply. The system initially operated in parallel with 700 gpm flowing through each vessel. Vessels were changed-out and replaced with the better-performing resins once effluent levels exceeded their high target of 20 ppt PFOA+PFOS. Each vessel pair, once filled with the same resin, could be operated in parallel series with 1,400 fpm flow through worked with the City of Stuart to evolve its water system and create the safest drinking water for its citizens, as it faces the negative impacts of PFAS long after they’ve been eliminated from standard consumer products. Participants in this session will see how the system was designed and installed and the results of the various resins within the system over the past four years.