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17 <br /> THE CITY OF <br /> CITY COUNCIL AGENDA REPORT <br /> pL£ASANTON <br /> December 6, 2022 <br /> Operations Services <br /> TITLE: ACCEPT WATER QUALITY UPDATES RELATED TO THE CITY'S WATER <br /> OPERATIONS: RECEIVE A PRESENTATION ON ZONE 7 WATER <br /> AGENCY'S GROUNDWATER MODELING AND PFAS CONTAMINATION, <br /> AFFIRM THE CURRENT OFFLINE STATUS OF WELLS 5 AND 6, AND <br /> HOLD A PUBLIC HEARING AND ACCEPT THE CITY'S 2022 PUBLIC <br /> HEALTH GOALS REPORT <br /> SUMMARY <br /> This report addresses several water quality updates related to the City's water operation <br /> to inform the City Council and the community about these matters. <br /> Zone 7 Water Agency recently completed a groundwater modeling analysis of <br /> mobilization of the PFAS plume under different drought management pumping <br /> scenarios. The findings from the modeling study were presented to the Zone 7 Board of <br /> Directors on August 31, 2022. Zone 7 staff will be providing the same presentation to <br /> the City Council. <br /> Perfluorohexanesulfonic acid (PFHxS) is a member of a large class of chemicals known <br /> as per- and polyfluoroalkyl substances (PFAS). In 2019, the City's well 8 was taken <br /> offline when it exceeded the PFAS notification and response levels in effect at that time. <br /> Now, new State health-based notification and response levels have been established <br /> for PFHxS, effective January 1, 2023. As the PFHxS concentration in the City's well 5 <br /> has exceeded, and well 6 levels nearly exceed, these soon to be in effect notification <br /> and response levels, the City turned off both wells on Wells 5 and 6 as of November 2, <br /> 2022. <br /> As a water purveyor, every three years the City must prepare a special report for the <br /> public which provides information about water quality constituents detected in the <br /> drinking water and how those constituents relate to State of California Public Health <br /> Goals (PHGs). <br /> RECOMMENDATION <br /> That the City Council: <br /> 1) Receive presentation from Zone 7 staff on its regional groundwater modeling and <br /> PFAS contamination as foundational information for current and future decision- <br /> making; <br /> 2) Keep wells 5 and 6 offline while PFHxS concentrations exceed 3ng/L, and <br /> purchase replacement water supply from Zone 7 until a water supply alternatives <br />