Currently, the Arizona Department of Environmental Quality (ADEQ) does not permit the City of Sedona to dispose of treated wastewater (effluent) beyond the boundaries of its property.

The city currently disposes of its effluent by spray irrigation, plant transpiration in wetlands, and evaporation from holding ponds. Essentially the water evaporates or is allowed to soak into the ground. All of these approaches require significant amounts of land (the wastewater facility covers about 426 acres with about 282 acres used for spray irrigation and 27 acres for wetlands/infiltration) to dispose of approximately 1.2 million gallons a day (1.2 MGD). As the city reaches build-out this quantity is expected to eventually increase to 2.5 MGD.

According to the report, the city's wastewater treatment plant has adequate disposal capacity for the next five years at the city's current growth rate.

Then what?

At the Sedona City Council meeting on July 8, 2008, the Sedona City Council will hear the possible alternatives for disposing of treated wastewater.

The Environmental Protection Agency (EPA), Arizona Department of Water Resources (ADWR), and Arizona Department of Environmental Protection (ADEQ), the agencies that protect state resources, also want to know how the city will dispose of its effluent.  Their standards prohibit any degradation of water quality in Oak Creek which they have labeled "dedicated unique water." ADEQ has stated “…that no new or increased loading to Oak Creek or its tributaries will be allowed.” 

Of significance is that wetlands will not solve the long term problem of the ability to legally dispose of the recurring and increasing daily effluent projected at build-out. 

Recharging directly into the Verde River basin is a possible option but it would involve the construction of a 9 mile pipeline and could cost the city $10-$15 million.

The most likely option involves construction of approximately a 4 ½ mile transmission line along SR 89A into an injection well site, known as the Gyberg Wash, on Arizona State Land property. The estimated cost to lease the land for 20 years and develop the property for recharge injection wells is $3.5 million. Revenue from the project could be realized from the sale of water credits to municipalities or developers who wish to withdraw water from the Verde River aquifer based on water credits generated by the city's injection of water into the aquifer.

The possibility also exists that the city may find someone who wants to purchase the effluent
water credits who is willing to pay for the construction and operation of the recharge infrastructure.

Despite an off-site solution, the City Engineer recommends retention of some on-site disposal capability in case the quality of its effluent does not meet the quality levels necessary for off-site disposal.

source:  City of Sedona

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