Hargis is currently assisting the Arizona Department of Environmental Quality (ADEQ) in protecting the Tucson Water’s Central well field by investigating the nature and extent of per- and polyfluoroalkyl substances (PFAS) contamination in the regional aquifer and remediation of the plume by ex-situ treatment.  The Central well field serves as the primary drinking water supply for over 65,000 people and the sole alternate drinking water supply for 600,000 people.

Scope of Work
The project was initiated after Tucson Water detected high concentrations of PFAS in supply wells just north of the Davis Monthan Air Force base.  H+A compiled a team of experts to conduct site investigations and remedial design in parallel to meet an accelerated schedule.   Our project team included Carollo for the treatment system design and construction oversight and, Smyth Industries for construction services and operation and maintenance services.

Field investigations have included the collection of in-situ groundwater samples to evaluate the vertical extent of contamination; installation of a network of monitor wells; and sampling and analysis of groundwater from monitor wells, private wells, and municipal supply wells. 

A total of eight groundwater monitor wells, some over 500 feet deep, have been installed to characterize the nature and extent of the PFAS plume which is over two miles long.

Project Status
H+A has teamed with Environmental Simulations, Inc. to construct a groundwater model to simulate the movement of PFAS to aid in remedial wellfield design.  A well head pilot treatment system for the removal of PFAS by ion exchange technology was completed in December 2021 and has been operating since January 2022.  

In 2022, the National Ground Water Association awarded ADEQ with the Outstanding Groundwater Project Award for Groundwater Remediation for Central Tucson PFAS Project. 

Services Provided

  • Remedial Investigation
  • Remedial Design & Construction
  • Drilling & Well Installation Support
  • Remediation O&M Support
  • Groundwater Management
  • Permitting & Compliance


Hargis Projects


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