Central Tucson Per & Polyfluoroalkyl Substances Project

 Central Tucson Per & Polyfluoroalkyl Substances Project

Hargis has worked with the Arizona Department of Environmental Quality (ADEQ) on various projects to investigate and remediate per- and polyfluoroalkyl substances (PFAS) in the Tucson area including:

Central Tucson PFAS Project: Hargis is assisting ADEQ in protecting the Tucson Central well field by investigating the nature and extent of PFAS contamination in the regional aquifer and containing 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. The project was initiated after Tucson Water detected high concentrations of PFAS in supply wells just north of the Davis Monthan Air Force base. Hargis 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. Additionally, Hargis has teamed with Environmental Simulations, Inc. to construct a groundwater model to simulate the movement of PFAS and aid in remedial wellfield design. A pilot treatment system was completed in January 2022 for the removal of PFAS by ion exchange technology and full-scale remedial design is on-going.  In August 2022, ADEQ received the Outstanding Groundwater Project Award for Groundwater Remediation from the National Groundwater Association for this project.

Marana Sampling Program Hargis conducted a reconnaissance sampling program along a 24-mile stretch of the Santa Cruz River in northwest Tucson and the Town of Marana for the presence of PFAS and 1,4-dioxane. Surface water samples along the Santa Cruz River and groundwater samples from monitor and irrigation wells were collected upgradient of the Marana municipal supply wells.

Tucson International Airport Superfund Site Hargis provides ADEQ and the Environmental Protection Agency (EPA) sampling, testing and consulting services for the presence of VOCs, 1,4‑dioxane and PFAS at the Tucson International Airport Area Superfund Site. Specific tasks include evaluation of sampling protocols and establishing project specific sampling and analysis procedures, coordination with environmental laboratories and EPA consultants, and collection and analysis of groundwater samples from monitor wells and private water supply wells. 


Key Accomplishments

  • Compiled a team of experts to conduct site investigation, remedial design, and construction of a remediation system in parallel.
  • Conducted field investigations including installation of a network of monitor wells, groundwater sampling, and surface water sampling.
  • Developed project specific sampling and analysis protocols.