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Page-Trowbridge Ranch Landfill | Hazardous Waste Site


Page-Trowbridge Ranch Landfill
One mile north of State Hwy 77 (approximately seven miles west of Oracle)
Pinal County, AZ

Discovery Date:


Contaminants of Concern (COCs):

  • Volatile organic compounds (VOCs)

Affected Media:

  • Soil
  • Vapor Intrusion (VI)

What are My Health Risks: 

For Soil | There is little to no health risk unless there is contact with skin or ingestion of contaminated soil.

For Vapor Intrusion (VI) | There is little to no risk of VI unless your residence or workplace is immediately above subsurface pollutants that evaporate at room temperature and have a direct pathway to indoor air.

Site Summary:  

The site is a closed hazardous waste landfill owned by the University of Arizona (UArizona) consisting of two landfill units: Unit A to the north and Unit B to the south. Chemical and low-level radioactive laboratory waste were disposed of at the site. All disposal activities ceased in 1986. The landfill units were capped and certified closed in 1997. An earthen cover that supports native grass vegetation was placed on top of the landfill. Culverts and storm water channels were installed to divert rainwater from the surface of the site to minimize percolation into the subsurface soil. The landfill has four onsite groundwater monitoring wells which are sampled semiannually. Groundwater is approximately 640 feet below the site. An onsite soil vapor extraction system operates to capture any vapors found below the landfill units. The site is secured by a 6-foot-high chain-link fence with barbed wire. The landfill is subject to a hazardous waste permit issued in 2001 and renewed in 2011. 

Because Unit B contains low-level radioactive laboratory waste, it is also regulated by the Arizona Department of Health Services (ADHS) Bureau of Radiation Control | View >

Corrective Action:

  • Soil Investigation Workplan – July 2002
  • Interim measure investigation – November 2003
  • Interim response action 
  • Post-Closure Permit
  • Human Health Risk Assessment is being updated – March 2023

More Information:

The renewal post-closure RCRA permit was issued on June 13, 2022 | View Final Documents >

For more information on this site, contact UArizona's Chief Risk Officer or ADEQ site manager:

  • UArizona Chief Risk Officer | 520-621-5392 | Email >

ADEQ Hazardous Waste Permits | 602-771-8727 | Email >