Thomas Groundwater Treatment Facility and Improvements to the Central Groundwater Treatment Facility


Project Information

The city of Scottsdale is constructing a new Reverse Osmosis water treatment facility, the Thomas Groundwater Treatment Facility (TGTF), on Thomas Road adjacent to the existing Central Groundwater Treatment Facility (CGTF) at Pima Park. In addition to the new treatment plant, the CGTF will be undergoing operational improvements that will include the construction of a new building within the walls of the existing plant.

About the CGTF

The CGTF treats water pumped from groundwater aquifers in south Scottsdale that contain Trichloroethylene (TCE). The aquifers collectively make up the EPA-designated Superfund site North Indian Bend Wash.

In November of 2015 funds to design and build the station were approved by the voters as part of the bond election held in November 2015.

Through airstripping technology, the CGTF removes the TCE from the groundwater to provide both a clean-up remedy for the aquifers and to allow the water to be used for the Scottsdale community. The facility removes TCE from the water to a level that is considered non-detect (less than 0.5 parts per billion), and is far below the EPA standard of 5 parts per billion.

The current operational improvements are not related to the superfund cleanup. Additional information is available on our North Indian Bend Wash Cleanup web page.

Why is the new plant – the TGTF – necessary?

The CGTF treats water from four different wells in south Scottsdale, each of which presents a different water quality challenge. To meet Scottsdale’s high water quality standards, the treated water from the various sources must currently be blended together through a complex, operationally challenging blending scheme.

The TGTF will receive and treat a side stream of product water discharged from the CGTF. The treated side stream will then be blended with the remaining CGTF product water to achieve the desired finished water quality and eliminate the need for multiple blending plans.

Reduced Water Hardness

The chemistry of the raw water treated at the CGTF – like most of the source water in the southwest – is characterized as very hard. This natural hardness, combined with the airstripping process, has resulted in scale formation within the CGTF and in the distribution system, which has created an ongoing operation and maintenance challenge and has been an ongoing customer concern. The TGTF and operational improvements to the CGTF will have the added benefit of reducing hardness in the finished water.

Project Information

Budget: $25.1 million

Sponsoring Division: Water Resources

Funding Source: Water Rates & Municipal Property Corporation Bonds

Project Location: Northeast corner of Hayden and Pima roads

Contact Information

City of Scottsdale - Capital Project Management

7447 E. Indian School Road
Scottsdale, AZ 85251
P: 480-312-7250

Elaine Mercado, Project Manager
P: 480-312-7985

Proposed Improvements

Rendering 1