In 1981, groundwater contaminated from industrial chemicals, primarily trichloroethylene (TCE), was discovered in the southern part of Scottsdale. Investigation revealed that the contamination was the result of past chemical disposal by several industrial companies in the area.

The U.S. Environmental Protection Agency declared the contaminated aquifer a Superfund site, namely the North Indian Bend Wash Superfund Site, in 1983. The area affected is from McDonald Road to the north, Granite Reef Road to the east, Scottsdale Road to the west, and McKellips Road to the south. View map.

In some locations, the groundwater contamination has extended beyond these boundaries and those locations are considered part of the Superfund site.
Once the presence of industrial chemicals was discovered, Scottsdale stopped using these wells for drinking water purposes.

The EPA identified the parties potentially responsible for causing the contamination and determined that a long-term cleanup effort would be required. The parties potentially responsible for the contamination include – Motorola Solutions (formerly Motorola, Inc.), GlaxoSmithKline (formerly SmithKline Beecham) and SMI Holding LLC (formerly Siemens) – are responsible for all costs associated with the cleanup. The State of Arizona’s Department of Environmental Quality (ADEQ) and Department of Water Resources (ADWR) are overseeing the cleanup for the state.

Clean-up Remedy

To clean up the site and return the wells to drinking water use, the potentially responsible parties built the Central Groundwater Treatment Facility (CGTF), located near Pima and Thomas roads. This treatment plant is able to treat water pumped from up to four groundwater wells that contain TCE using air stripping.

The CGTF is owned and operated by the city of Scottsdale. Scottsdale ensures that the water produced by the plant meets or surpasses all federal and state standards for safe and healthy drinking water, with oversight from the EPA in cooperation with ADEQ. 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.

In 2013 construction was completed for a new treatment facility for the long-term remedy for the NIBW site. The NIBW GAC Treatment Facility (NGTF) is located on the southeast corner of McDonald Drive and Cattletrack Road. This facility extracts water from well PCX-1 and uses a liquid Granular Activated Carbon treatment process to clean and treat the water.

Treated water from the NGTF is pumped to Scottsdale Water’s Chaparral Water Treatment Plant, located at McDonald and Hayden roads, where it is combined with other water in our system and then pumped into our distribution system. When the Chaparral Plant cannot take the water, the treated water is discharged into the nearby Arizona Canal.

Cleanup Timeline

It’s estimated that the cleanup will take approximately 50+ years. However, large portions of the groundwater plume cleanup should be completed before that time. As of monitoring in 2021, the upper aquifer plume has decreased in size by 92 percent, and the total mass of contaminants in the upper aquifer groundwater has decreased by over 98 percent.

Clean-up will continue in the middle and lower aquifer until they reach the same level of clean-up. This complete remedial time frame is undetermined but expected to take 50+ years.

Superfund and Your Property

If you own a home within the Superfund site, you have no liability for the contamination caused by others. Arizona has its own mini-Superfund law that protects innocent homeowners from cleanup liability.

However, if you are selling a home within the NIBW Superfund site, you must disclose the home is in a Superfund site to potential buyers. Whether disclosure is made by the seller or a real estate agent, the Superfund designation should be disclosed at the first discussion about the property. This will avoid any last-minute questions that could complicate the transaction. If you aren’t sure if your home is within the site, please call 480-312-8712.

For More Information

• Susan Butler, Scottsdale Water, 480-312-8712
• Carolyn d'Almeida, US EPA, 415-972-3150 or 800-231-3075
• Wayne Miller, ADEQ, 602-771-4121 or, toll free, at 800-234-5677
• US EPA Region IX
• ADEQ Superfund