Protecting Groundwater for Future Generations

The next phase of this important project to ensure clean groundwater underneath the former Cave Creek Landfill is set to begin on July 26, 2021. The work to protect Arizona's most precious resource consists of two efforts; 1) completing the Water Treatment System (WTS) to extract, clean and return clean water to the aquifer, and 2) drilling additional wells, some to extract additional water for the WTS, and some to test water quality and monitor progress. This also includes constructing a 1,000-foot underground power line, and some additional non-visible equipment at the injection well site on Sleepy Ranch Road.

 Maricopa County is fully aware and sensitive to the temporary inconveniences a few residents may experience during the projects. Recommendations from residents have been solicited, and many are being implemented.

History of the Cave Creek Landfill

Cave Creek Landfill (CCL) began operations around 1965 in the area known as the “Old Landfill.” Somewhere around 1984, operations shifted to the “New Landfill.” The CCL stopped accepting waste in 1998. (A transfer station continues to operate, but all waste is hauled offsite.) As was typical with landfills operated at those times, liners were not required. The CCL was permitted to accept residential and commercial municipal solid waste and other wastes including: appliances, barnyard and stable waste, demolition material, non-infectious medical waste, domestic animals (large and small), green waste, foods, and inert materials. 

As required by law in 1993, the County installed two down gradient groundwater monitoring wells (south and southeast of the landfill) and began to monitor these wells along with an already existing up gradient well (north of the landfill). Each well is located on County property. In December 1997, trichloroethene (TCE) above the Aquifer Water Quality Standard of 5.0 micrograms per liter (ug/L) was found in the monitoring wells. Maricopa County entered into a Consent Order with the Arizona Department of Environmental Quality (ADEQ) which assigns the responsibility for site remediation to the County. ADEQ approved a Remedial Action Plan (RAP) and continues to approve periodic revisions to the plan.

The groundwater contamination from CCL is over 600 feet below the ground surface and does not impact any drinking water sources or any other known sources of water use. Remediation is ongoing and will continue until complete to the satisfaction of ADEQ.

The first step of removing contamination is to address the harmful vapors in the soil, an initiative that has been underway since 2015. To date, the County has removed more than 46,000 pounds of contaminants. The second step of removing contamination is to clean the groundwater. This work began in 2017. The most effective way to accomplish this critical task is to extract the water, filter out the contaminants, and return the clean water to the aquifer. (See Remediation Activities.)

  1. Consent Order
  2. Remedial Action Plan
  3. Site Characterization Report

A Consent Order is a binding, enforceable contract. In the case of an environmental liability, this document will outline the obligations of the responsible party and provide for oversight of remediation. The original Consent Order for the Cave Creek Landfill Remediation Project was filed in 1998 and has been updated since. View the most recent Cave Creek Consent Order (PDF).


Email the Project Coordinator
Phone (non-emergency): 602-506-7179