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C A RY, N O RT H C A R O L I N A A N N U A L WAT E R Q U A L I T Y R E P O R T 2 0 2 2 14 SUBSTANCE (UNIT OF MEASURE) HEALTH ADVISORY LEVELS (HALS) (ppt) PROPOSED MAXIMUM CONTAMINANT LEVEL (MCL) AVG. AMOUNT DETECTED RANGE DETECTED (ppt) Perfluorooctanoic acid (PFOA) 0.004 (interim)* 4 ppt 2.4 ppt 2.1–2.5 Perfluorooctane sulfonate (PFOS) 0.02 (interim)* 4 ppt ND ND–1 Perfluorobutanesulfonic acid (PFBS) 2000 1.0 (unitless) Hazard index <0.10 (unitless) Hazard index 3.1–4.3 Hexafluoropropylene Oxide Dimer Acid (HFPO-DA or GenX) 10 ND Perfluorohexanesulfonic (PFHxS) No current HAL ND–0.8 Perfluorononanoic acid (PFNA) ND–0.13 Perfluoroheptanoic acid (PFHpA) No proposed MCL 2.2 ppt 2–2.5 Perfluorobutanoic acid (PFBA) 9.5 ppt 8.2–11 Perfluoropentanoic acid (PFPeA) 9.3 ppt 7.5–12 Perfluorobutylsulfonamide (FBSA) 0.37 ppt 0.37–0.37 Perfluorohexanoic acid (PFHxA) 7.3 ppt 6.3–8.7 * Health advisory levels (HALs) for PFOA and PFOS are interim. The current most advanced PFAS testing methods are not able to accurately measure down to the interim HALs. For a complete list of substances tested, including non-detects, see 2022 Water Quality Testing Summary online: P E R F LU O R I N AT E D C O M P O U N D S I N 2 0 2 2 C A RY P R OAC T I V E LY I M P L E M E N T S A DVA N C E D T R E AT M E N T T E C H N O LO GY Cary has been actively following the national discussion of PFAS since we first tested for these substances in 2015 as part of UCMR3 or the Unregulated Contaminant Monitoring Rule and then subsequently tested and detected PFAS in late 2017. Cary proactively studied and pilot tested several water treatment optimization processes known to enhance PFAS removal in early 2018. One such process available for implementation was carbon adsorption with a product called powder activated carbon (PAC), which has multiple benefits for other stages of water treatment along with reducing PFAS. Studies indicated this method was beneficial and effective at further reducing PFAS at low concentration levels. As such, Cary immediately implemented this process continuously as part of our already advanced water treatment process during 2018 and we've been consistently using this process optimization for the past several years to improve PFAS removal, well before PFAS was proposed to be regulated. The combination of PAC with our existing process, including ozonation, provides an even higher level of sophisticated multiple barrier water treatment technology to support advanced treatment of both regulated and unregulated substances for removal from Cary's drinking water. Subsequent testing shows extremely low PFAS levels in finished drinking water that are below the newly proposed maximum contaminant levels announced by EPA.

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