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City of Pleasanton—Hidden Canyon Residences and Preserve Hazards and Hazardous Materials Draft EIR 3.8-2 FirstCarbon Solutions https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480016/EIR/3 - Draft EIR/21480016 Sec03-08 Hazards.docx with the substance. They can contaminate drinking water supplies when products containing PFAS are used or spilled on the ground and they migrate into groundwater, and, once in groundwater, PFAS can travel large distances and contaminate drinking water wells. Major sources of PFAS contamination include fire training/fire response sites, military bases, industrial sites, and landfills. In March 2019, the California State Water Resources Control Board (State Water Board) initiated a Statewide PFAS phased investigation for hundreds of drinking water sources, including Zone 7 Water Agency (Zone 7) and the Livermore District. The Livermore District has 12 groundwater wells within its service area. In March 2023, the United States Environmental Protection Agency (EPA ) issued a proposed National Primary Drinking Water Regulation (NPDWR) for certain PFAS. The proposed regulation calls for a maximum containment level for perfluorooctanesulphonic acid (PFOS) and perfluorooctanoic acid (PFOA) of 4 parts per trillion (ppt) each. Four additional PFAS—perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorobutanesulfonic acid (PFBS), and GenX chemicals— would have a combined hazard index (HI) limit of 1.0; the HI calculation would determine if the levels of these PFAS as a mixture pose a potential risk.2 According to the California Water Service (Cal Water) 2022 Water Quality Report for the Livermore District System, prior to issuance of this regulation, Cal Water had already proactively tested active sources in their systems for all six PFAS and had taken the affected sources out of service until treatment was installed. Thus, none of their active water sources have levels of the six PFAS compounds over current California response levels. The response level, which is the level at which a water system should make operational changes to reduce the concentration of a compound, is set with a margin of protection for all people (including sensitive populations) over a lifetime of exposure.3 On April 10, 2024, the EPA announced the final NPDWR for six PFAS, including individual Maximum Contaminant Levels (MCLs) for PFOA and PFOS at 4 parts per trillion (ppt); individual MCLs for PFHxS, PFNA, and GenX Chemicals at 10 ppt; and an MCL for a mixture of 4 PFAS (PFHxS, PFNA, GenX Chemicals, and PFBS) at no greater than an HI of 1.0.4 The EPA also finalized health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these PFAS. Public water systems must monitor for these PFAS and have 3 years to complete initial monitoring (by 2027), followed by ongoing compliance monitoring. Public water systems will have 5 years (by 2029) to implement solutions that reduce these PFAS if monitoring shows that drinking water levels exceed these MCLs. Primary agencies, such as the State, will have up to 2 years to adopt standards that are no less stringent than the federal standards.5 2 California Water Service (Cal Water). 2022. Water Quality Report for Livermore District, Livermore System. Website: https://www.calwater.com/docs/ccr/2022/liv-liv-2022.pdf. Accessed March 24, 2024. 3 Ibid. 4 Zone 7 Water Agency. 2020. PFAS Information. Website: https://www.zone7water.com/pfas#:~:text=On%20April%2010%2C%202024%2C%20the%20U.S.%20Environmental%20Protection,Z one%207%20has%20been%20doing%20voluntarily%20since%202019. Accessed March 24, 2024. 5 Ibid.