Since its incorporation, the city of Sedona has spent at least $340 million — in inflation-adjusted dollars — on building, upgrading and operating its Wastewater Reclamation Facility, which is also responsible for 83% of all electrical power consumed and electricity-related greenhouse gases emitted by city facilities.

Origins

According to the city’s 1988 Wastewater Facility Plan, Sedona’s wastewater plant originated in a 1978 decision by the Northern Arizona Council of Governments to adopt a 208 Water Quality Management Plan under the terms of the Clean Water Act.

Amendments to this plan in 1984 and 1988 called for the creation of a central sewer system serving the entire Sedona planning area.

On April 18, 1988, the Arizona Department of Environmental Quality issued a paper stating that the Sedona Sanitary District — which predated the city’s incorporation — was making insufficient progress in implementing the 208 Plan. ADEQ threatened to withhold approval of any new wastewater systems if the district and later the city did not comply with the timeframe specified in the plan for installing a central sewer.

Faced with the ADEQ ultimatum, Sedona voters subsequently approved the installation of a central sewer system in a referendum on June 6, 1989.

The statutory authority for ADEQ’s ability to issue such an ultimatum is Arizona Revised Statutes §49-106, which provides that rules adopted by the department shall be observed throughout the state and enforced by the appropriate local council or officer, and Arizona Administrative Code §18- 5-303, which requires wastewater facilities to conform to water quality management plans established by designated planning agencies.

Construction of Sedona’s central sewer system did not eliminate the use of septic systems within the city.

“The city provides wastewater services to approximately half of Sedona residents and businesses,” the city’s website currently states. “The remainder have private sewer and septic systems.”

Title 13.15 of the Sedona City Code now requires all properties within reach of the city sewer system to connect to the system, and prohibits the granting of any new permit to operate a septic system or private sewer except on a temporary basis.

Economics

The initial construction cost for building Sedona’s sewage plant was estimated at $22.5 million in 1989. Adjusted for inflation according to the Consumer Price Index, equivalent to $54.54 million in 2023 dollars.

In 2000, the city began a round of upgrades to the sewage plant at an estimated cost of $8.8 million, equivalent to $15.356 million in 2023 dollars.

The city’s budgets from fiscal year 2004 to the present show that operation and maintenance of the sewer system, including construction and capital improvement projects, cost the city at least $212.9 million during that period. Adjusted for inflation, this would be over $270 million in 2023 dollars.

Administrative costs of $11.4 million were the smallest component of the plant’s expenses. The operations budget for these 19 years came to just over $47 million, with individual years’ allocations for operating expenses having roughly doubled over the past decade.

Construction and capital improvement projects related to the sewer system cost Sedona residents over $67.3 million, while the facility’s debt service costs for this period were at least $87 million. Arriving at estimates of city spending on these components of the system is complicated by the alterations made to the city’s budget format in FY 2012, when staff decided to list construction and capital improvements separately from the wastewater budget without an annual total, and in FY 2015, when debt servicing costs were also listed separately.

Total spending on the city’s sewage plant over the last 34 years comes to at least $340 million in inflation-adjusted dollars, or an average cost of $10 million per year.

An editorial in the Sedona Red Rock News on May 31, 1989, that reviewed arguments against the plant noted that one of the objections made by residents was that incremental price increases would ensure the cost of the system was “going to be $300 million before they are done.”

Estimated 30-year costs for alternative methods of waste disposal [on the basis of 6,788 housing units and 2,789 hotel rooms] are:

• Septic systems: $84.9 million, including $54 million for the up-front cost of 7,718 septic systems [assuming three hotel rooms to be equivalent to one residential unit] and $30.9 million to have those tanks pumped every three years
• Incinerating toilets: $264.2 million, including $130.9 million for initial cost and replacement costs after 15 years, on the basis of two units per house and one per hotel room for 16,365 total units, and $133.3 million for power consumption on the basis of 2 kWh consumption per use, six uses per day and an average electricity price of 6.2 cents per kWh
• Composting toilets: $66.8 million, including $65.5 million for initial cost and replacement costs after 15 years and $1.3 million in electrical costs for evaporation fans

Energy and Emissions

The city of Sedona consumed approximately 3,961 MWh of electricity in calendar year 2022, down slightly from 3,976 MWh in 2020. The wastewater plant and its associated systems were responsible for 3,302 MWh and 3,190 MWh of this usage, respectively, up from 2,224 MWh in fiscal year 2014. For 2022, this represented 83% of the city’s total electricity usage.

Meanwhile, the amount of wastewater processed by the plant has remained very consistent, varying from 403.89 million gallons in FY 2015 to 402.6 million gallons in FY 2021.

According to a 2020 study by the University of San Francisco, Arizona Public Service’s current generation mix produces greenhouse gas emissions of 440 grams of CO2 per kilowatt-hour. On this basis, the wastewater plant’s electricity consumption caused the release of 1,544 tons of greenhouse gases in 2022. Studies of direct greenhouse gas emissions from wastewater facilities indicate that Sedona’s wastewater plant likely added another 300 to 500 tons of CO2 equivalent through emissions from the plant itself.

Average emissions per person, according to the Nature Conservancy, are 16 tons per year in the United States and 4 tons per year globally.

Estimated annual emissions for alternative methods of wastewater disposal include:

• Septic systems: 1,953 tons, on the basis of a typical system releasing 230 kg CO2 equivalent per year, according to the Water Environment Research Foundation
• Incinerating toilets: 34,682 tons on the basis of electricity consumption
• Composting toilets: 347 tons on the basis of electricity consumption

While anaerobic digesters have lower installation and emissions costs than sewer, septic, composting or incinerating methods of waste disposal, they must be maintained at a minimum temperature of 68 degrees Fahrenheit, whereas the average annual temperature in Sedona is 63 degrees. Anaerobic systems would require region-specific designs in order to function properly in Sedona’s climate, but could potentially achieve net zero emissions with further development.

Environmental Concerns

NACOG and ADEQ officials argued at the time of the system’s construction that it was a necessary measure to preserve groundwater quality and the health of Oak Creek. At a community meeting on May 11, 1989, city public information officer John Roberts claimed that Sedonans had been “overloading” the soil with wastewater for years and that 45% of the Sedona area had rock too close to the surface of the ground to allow leach fields to work properly.

Conversely, L. George Platt wrote a letter to the NEWS on May 4, 1988, in which he pointed out that “the waste disposal situation has been studied by two consulting engineering firms and both have stated that either a central sewer or on-site systems, properly installed and maintained, are equal from an environmental standpoint. The EPA has stated the same.” Current EPA guidance still indicates that a properly sited and installed septic tank poses no risk to water quality or human health.

The June 2002 update to NACOG’s 208 Plan admitted that “no new limits on existing septic systems [within the Oak Creek watershed] are justified at this time.”

According to Arizona Water Company division manager John Snickers, “there have been no reported incidences of contamination from a septic system in the city of Sedona or any illnesses as a result.” Yavapai County Development Services likewise has no record of any groundwater contamination resulting from a septic system within the city limits.

A partial list of known incidents of environmental contamination caused by Sedona’s central sewage plant includes:

• Feb. 26, 2008: View Drive, unknown amount
• Aug. 2, 2017: View Drive, unknown amount
• June 28, 2020: Canyon Drive Roundabout, 1,000 gallons
• July 7, 2020: Canyon Drive Roundabout, 2,000 gallons
• Aug. 4, 2020: Hillside Shopping Center, 15-20,000 gallons
• Oct. 28, 2020: Arroyo Pinon Drive, 500-700 gallons
• July 23, 2021: El Camino Lift Station, 1,500 gallons
• March 4, 2022: Center for the New Age, unknown amount
• March 28, 2023: Mystic Hills Lift Station, 22,000 gallons

“Spills don’t happen when managers are doing their jobs,” Sedona resident James Heyer said after the March 28 spill. “Spills don’t happen when workers pay attention and equipment is well maintained. Who got fired?”

Remediation

City sustainability manager Bryce Beck declined to comment on whether the city was investigating closure of the wastewater plant and alternative methods of sewage disposal as part of the update process for the city’s Climate Action Plan and sustainability plan, given the plant’s high environmental costs.

City communications manager Lauren Browne said that the city would not be investigating closure of the plant and claimed such a decision was “not viable.”