Location: 4051 N Higley Rd, Mesa, AZ 85215

Discovery Date: January 1996

Contaminants of Concern (COCs): Lead, Perchlorate, Volatile Organic Compounds(VOCs), 1-4 Dioxane

Affected Media: Soil and Groundwater 

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 Groundwater | If you are connected to a Public Water System (PWS) there is little to no risk of impact from exceedances because the water is filtered through the PWS for residential and business use | View Drinking Water Notices > 

If you have a private well in the vicinity of the exceedance, we encourage you to test the well water. 

Not sure what to test for? | Learn More > 

Site Summary:  

The Nammo Defense Systems, Inc. (NDS) facility and its corporate predecessors have manufactured and tested propellant-based products since the 1960s. Two known releases of contaminants of concern (COCs) to soil and groundwater have occurred during historical facility operations. One release occurred at an area known as the former thermal treatment unit (TTU) and the other at an area known as the Plant No. 3 former water bore out (WBO). Offsite groundwater impacts are present at both sites, and stakeholders with threatened groundwater wells have been identified and involved in pertinent environmental work at the facility. This webpage focuses on the TTU, except where otherwise noted.

Former Thermal Treatment Unit (TTU)

NDS is actively performing characterization and cleanup of site COCs at the TTU under an administrative order on consent (Consent Order) with the United States Environmental Protection Agency (EPA). The EPA is the lead regulatory agency at the site, but works closely with the Arizona Department of Environmental Quality (ADEQ) Hazardous Waste Program. Soils contaminated with perchlorate and lead at the TTU have migrated onto the neighboring Salt River Pima-Maricopa Indian Community (SRPMIC) lands. Additionally, groundwater contaminated with 1,4-dioxane, VOCs, and perchlorate has also migrated to lands owned by SRPMIC, and threatens the use of groundwater produced at production well PF-2. Well PF-2 resides on SRPMIC land leased to a primate research facility, produces non-potable water for facility use, and is monitored for contaminant presence. The EPA is working closely with SRPMIC to facilitate site investigation and cleanup.

Former Water Bore Out (WBO)

NDS is actively performing characterization and cleanup of site COCs at the WBO with oversight from the ADEQ Voluntary Remediation Program (VRP). ADEQ’s My Community webpage for the WBO resides with other sites overseen by the VRP | View Site > 

Current Status:

In 2021, NDS drafted a facility-wide current condition report and conceptual site model, both of which are in the process of finalization. Additionally, NDS is drafting a facility investigation work plan and will begin implementation of the work plan in 2023. Active extraction and treatment of TTU groundwater for COCs is ongoing.

Both EPA and NDS have created public webpages describing the site. A copy of the Consent Order and associated documents are available on the EPA webpage | View EPA Webpage >

NDS's webpage will act as a document repository for work plans and reports required by the Consent Order | View NDS Webpage >

Corrective Action:

• Ongoing groundwater monitoring
• Ongoing groundwater pump and treat remediation
• Multiple soil contaminant characterization actions
• Multiple contaminated soil removal actions
• In situ soil stabilization to decrease COC leachability to groundwater
• Enhanced in situ bioremediation pilot testing to treat groundwater
• Contingency plan for responding to impacts at non-potable production well PF-2