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BACKGROUND Perfluorooctanoic acid (PFOA) and PFOS are human-made substances of emerging concern that are part of a larger group of chemicals referred to as PFAS. PFAS have been used extensively in surface coating protectant formulations due to their unique ability to repel oil, grease, and water. Major applications have included protectants for paper/cardboard packaging, carpets, leather products, and textiles, nonstick coatings on cookware, and in firefighting foams. Exposure to unsafe levels of PFOA and PFOS may result in adverse health effects including developmental effects to fetuses during pregnancy, cancer, liver effects, immune effects, thyroid effects, and cholesterol changes. PFAS are primarily introduced into the body by the ingestion of contaminated food or liquid (including water). The major sources of PFAS are fire training/fire response sites, industrial sites (such as airports), landfills, and wastewater treatment plants. Groundwater contamination with PFAS has typically been associated with these sources. Although not currently regulated in drinking water, as of August 2019, the State Water Resource Control Board (SWRCB) Division of Drinking Water (DDW) has issued a Notification Level of 5.1 parts per trillion (ppt) for PFOA, a Notification Level of 6.5 ppt for PFOS, and a Response Level of 70 ppt for PFOA and PFOS combined. Notification Levels are concentrations that have been determined to not pose a significant health risk but warrants notification to governing bodies. Response Levels are concentrations where treatment or removal of the water source is recommended to reduce public exposure to the contaminant. As part of a statewide testing program being led by DDW, the City has conducted testing for PFOA and PFOS in water supplies. All three wells tested above the Notification Level for PFOS at the time of testing with Well 8 testing above the combined PFOA and PFOS Response Level. Upon initial (unconfirmed) test results, staff immediately placed Well 8 into the last priority facility to operate when trying to meet water demands. As a result, Well 8 has not operated since receipt of the initial test results and is only anticipated to operate under abnormal conditions such as extreme peak demand periods or if there are failures of other supply facilities. DISCUSSION The scope of this amendment is to investigate alternatives available to the City to treat PFAS at Wells 5, 6, and 8. The scope of work for this evaluation includes the following: • Groundwater quality review • Establish treatment target goals for evaluation that may include: o Response Level compliance o Notification Level compliance o Below detection limits • Treatment technology evaluations including: o Blending o Granular activated carbon (GAC) adsorption o Ion exchange (IX) resin treatment Page 2 of 3