Well Cluster 3 Arsenic Treatment Facility

Project Information

While Scottsdale is committed to maximizing our use of renewable surface water supplies (i.e. waters from the Central Arizona Project and the Salt River Project) and minimizing our use of groundwater, it is also essential to strengthen the resiliency of our water supply system in the event that CAP water deliveries are reduced or interrupted and as part of a long-term supply portfolio.

Part of the city's strategy to ensure the reliability of groundwater is to implement improvements to enable the delivery of groundwater from a series of wells, known as Cluster 3 wells, through the potable water distribution system.

Arsenic concentrations in the Cluster 3 wells' groundwater are approaching the U.S. Environmental Protection Agency maximum contaminant level for arsenic of 10 micrograms per liter (µg/L) and exceed the city's operational goal of 8 µg/L and will require arsenic treatment to be put into service.

In 2018, the City retained Carollo Engineers, Inc. to perform an Arsenic Mitigation Alternatives and Feasibility Analysis study for Well Clusters 3 and 6. Based on the results of this study, the city is currently proceeding with centralized arsenic treatment for the Cluster 3 wells via design and construction of a new arsenic treatment facility. The new ATF will be constructed on the remainder of the city parcel to the west of the current Scottsdale Water Site 53 walls, located at the northwest corner of Jomax Road and N. 62nd Street, within the current property boundary lines.

In addition to the new arsenic treatment facility, improvements to the site will include a new aquifer storage and recovery well, a new backup power generator and full replacement and modernization of all electrical equipment and facilities. The existing electrical building will be demolished and replaced by a new prefabricated metal building.

To accommodate the new treatment facility, the west wall of Site 53 will be extended further west. The north and south walls will be extended on their current lines to the new west facing wall to enclose the site. The extended south wall will include several new vehicle gates to provide access from Jomax Road to both the treatment plant and well areas.  The remaining site boundary wall boundaries will not change.

The project is anticipated to begin in 2021 and last approximately one year.

Proposed Site Plan