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Prioritize efforts on advancing the planning, design, and construction of self - implemented PFAS treatment at City wells. The primary reason is that this solution allows the City to maintain implementation control againsta potentially tight regulatory deadline. Continue to explore regional solutionswith Zone 7 on a parallel path. Include flexibility and checkpoints in the work plan that allows adjustments to or off - ramps from self -implementation as variables get furtherdefined. The schedule shown is preliminary and forgeneral guidance atthis time. The schedule will be defined in more detail as planning and design progresses, and as DDW regulatory schedules are further detailed. The City has completed activities from the initial phases of the work plan and a summary of their outcomes are listed below. PFAS Treatment Feasibility at City Wells The City hired Carollo Engineers to perform a feasibility study of PFAS treatment at Wells 5, 6, and 8. Refer to Technical Memorandum 3 included as part of the July 2020 Water Quality Evaluation located at the following link: Water Quality Evaluation. 1. The evaluation considered three treatment goals that bracket possible future PFAS regulations: • High Treatment Goal — Equivalentto current response levels for PFOA and PFOS. • Medium Treatment Goal— Equivalentto current notification levels for PFOA and PFOS. • Low Treatment Goal —Reduce PFAS concentrations (EPA 537/537.1) below current detection limits. 2. The evaluation considered fourtreatment options: • Blending—This method was found to not be technically feasible and eliminated from furtherconsideration. • Reverse Osmosis Treatment —This method was found to not be economically feasible and eliminated from further consideration. • Gran u lar Activated Carbon (GAC) Treatment o Removes PFAS by adsorption2. o In general, requires more GAC media and thus vessels3on a per unit treatment basis when compared to ion exchange treatment. However, the unitcost of GAC media is less expensive than the media used in ion exchange. o Once the GAC media can no longer sufficiently remove PFAS, the media and trapped PFAS molecules are typically incinerated and destroyed. z Adsorption is the process of removing contaminants or unwanted molecules from water by their adhesion to a treatment material (also known as media). 3 Vessels are hollow containers used to hold media. Vessels facilitate the adsorption process by allowing water to be passed through them edia. Page 4 of 9