Sedona City Council received an update on the city's wastewater reclamation facility plan and options for managing effluent, including PFAS treatment, reclaimed‑water delivery for parks and an advanced water purification (potable reuse) system. The presentation by Corolla Engineers showed the plant can handle projected build‑out flows from a hydraulic and treatment‑process standpoint but identified rising concentrations of PFAS and other constituents and large, conceptual costs for treatment and delivery options.

The facility plan presentation opened with Roxanne, a city staff member, who said the city had paused some FY25 projects so consultants could complete a comprehensive plan. "We identified either we need to move forward with some recharge wells or we need to make some significant improvements to our irrigation," Roxanne said. Jessica Dreeseng, principal with Corolla Engineers, summarized the study and noted the team evaluated capacity, PFAS treatment alternatives and effluent‑management options downstream of any PFAS work.

Why it matters: PFAS (per‑ and polyfluoroalkyl substances) are persistent at nanograms‑per‑liter levels and are the subject of new federal drinking‑water maximum contaminant levels (MCLs). Sedona's plan assumes state rulemaking will tie wastewater limits to drinking‑water MCLs and recommends the city consider PFAS treatment as a regulatory and public‑health risk even as state rulemaking proceeds.

Key findings and numbers

- Current and projected flows: Corolla Engineers used five years of data and process checks and reported an average daily flow near 1.16 million gallons per day (MGD) and a projected build‑out average of about 1.6 MGD. Firm, process‑level capacities for major units were reported sufficient for the anticipated build‑out, with the consultant noting some piping upsizing near the UV disinfection unit is needed.

- PFAS monitoring: Staff has begun monitoring influent and effluent PFAS at the plant and found occasional exceedances when compared to drinking‑water MCLs; the presentation warned PFAS species can transform during treatment and effluent values sometimes differ from influent values.

- Treatment options for PFAS: The study evaluated two established technologies: granular activated carbon (GAC) and ion exchange (IX). Both require pretreatment (for example, ozonation and biological activated carbon filtration) to reduce total organic carbon for effective operation. Dreeseng said both approaches are used in Arizona and noted tradeoffs: GAC can be regenerated (with concerns about PFAS in regeneration residuals), while current ion‑exchange media for PFAS generally requires disposal of spent media.

- Waste/residuals management: Several speakers noted that membranes (reverse osmosis, RO) or IX produce concentrates or spent media that may require offsite handling and disposal. Consultants and staff said some utilities currently truck concentrated residuals long distances (examples cited included facilities shipping material to Nevada or Kentucky) and that evolving regulation and risk assessments could change allowable disposal pathways.

- Conceptual costs (Class 5 / feasibility level): The consultant presented broad, parametric cost ranges with +/- uncertainties typical at 0% design. Representative figures in the presentation (January 2025 dollars) included: PFAS treatment (GAC or IX) roughly in the $26–32 million range depending on phasing; reclaimed‑water delivery alternatives from approximately $14 million (to serve a high school) up to about $228 million (a system serving multiple parks and neighborhoods); advanced water purification (AWP)/potable reuse conceptual ranges from roughly $30 million on the low carbon‑based end up to more than $100 million for an RO‑based full build‑out system, with conveyance costs additional. The consultants emphasized accuracy ranges for these estimates can be large (about -50% to +100%) at this stage.

Council and staff discussion

Councilors questioned plant capacity, redundancy of UV disinfection, whether the existing unused effluent pipe to West Sedona could be rehabilitated for reclaimed‑water delivery, and the potential to use reclaimed lines for firefighting. Staff and consultants noted the existing line (an earlier effluent return main) terminates near Sunset Park, is ductile iron, has not been actively used, and would require testing and likely rehabilitation before reuse.

Councilors and staff discussed strategy and timing. Roxanne and consultant staff recommended including PFAS treatment costs in the city's 10‑year capital improvement plan (CIP) so the city can model financial impacts in future rate studies, while also watching state rulemaking. City Manager Annette (last name not specified) said staff is not recommending capital expenditures in the next CIP cycle but has placed high‑level PFAS cost estimates in a 10‑year CIP draft to inform future rate modeling.

Regulatory timing and next steps

Consultants and staff said federal drinking‑water MCLs for several PFAS compounds are final and that drinking‑water systems face compliance windows (consultants cited 2029 as a federal compliance milestone for drinking water). Arizona Department of Environmental Quality (ADEQ) rulemaking to address PFAS in wastewater (and to align some wastewater permits such as aquifer protection permits with drinking‑water limits) was described as beginning but still in development; staff said ADEQ's formal rulemaking process and timing remain uncertain and that ADEQ may first require baseline monitoring of wastewater plants across the state.

Policy choices

Staff described three broad effluent management approaches the council could weigh: (1) keep and improve irrigation/disposal (some park irrigation and limited pipe rehabilitation); (2) rely more on recharge wells (building additional injection/recharge infrastructure and potentially abandoning irrigation of certain acres); or (3) pursue advanced water purification and deliver potable water to a retail water provider (Arizona Water Company was discussed as the likely delivery partner). Staff noted the AWP option would be a policy choice rather than a regulatory requirement and would require extensive stakeholder discussions and cost‑sharing conversations with regional water providers.

Quotations from the meeting

"We identified either we need to move forward with some recharge wells or we need to make some significant improvements to our irrigation," Roxanne said, explaining why the facility plan was prepared.

"We are here today to provide you with an update of our wastewater reclamation plant facility plan," Jessica Dreeseng, principal with Corolla Engineers, told the council.

John (Arizona Water Company representative) said his company has begun evaluating treatment for PFAS at its own facilities and that activated carbon has been a leading option in some of their locations.

Council direction and staff recommendations

- Staff asked the council for input on evaluation criteria for ranking options (cost effectiveness, environmental impacts and public health, water resource resiliency, operational reliability, and economic impacts). Councilors asked that public health and long‑term livability be explicit criteria.

- Staff recommended that the city include PFAS treatment cost estimates in the 10‑year CIP and use that input in the forthcoming rate study so the council can see potential customer impacts. Staff said they are not recommending building PFAS treatment or AWP systems immediately and want to continue stakeholder outreach and wait for additional regulatory clarity before committing to large capital projects.

What the council will decide next

Staff said ADEQ rulemaking activity later this year would be an appropriate time to revisit the plan. Consultants and staff also recommended pilot‑scale testing and additional water‑quality studies to choose between GAC and IX if Sedona moves forward on PFAS removal.

Ending

The facility plan gave the council options rather than a single recommended capital project: continue monitoring and include PFAS costs in long‑range financial planning; pursue reclaimed‑water delivery by rehabilitating existing pipe and building new conveyance (a large capital program); or consider advanced water purification and potable delivery in partnership with a retail supplier. Staff said timing and costs remain uncertain until ADEQ and other regulators finish rulemaking and until the city performs pilot testing and more detailed design.