Hazardous Materials Response Unit Provides Specialized Support for Hazmat Incidents Across Arizona

The Arizona Department of Public Safety's (AZDPS) Hazardous Materials Response Unit (HMRU) is dedicated to providing statewide response and support for incidents related to hazardous materials (hazmat), radiological materials, and weapons of mass destruction.

All Arizona State Troopers are trained to recognize and take protective measures for hazmat incidents. However, HMRU troopers and specialists have extensive training, specialized certifications, and field experience, providing them with the qualifications, knowledge, and skills necessary to address complex hazmat incidents. The HMRU handles transportation and non-transportation incidents, responding to hazardous materials' actual or potential uncontrolled discharge. The HMRU responds to an average of 200 incidents annually, with calls for service ranging from minor fuel leaks to clandestine drug labs to complex collision scenes.

One such incident occurred on November 23, 2022, when state troopers responded to reports of a single-vehicle collision involving a commercial propane tanker on southbound State Route 77 at milepost 154, located south of Globe. The commercial propane tanker traveled off the right side of the roadway, colliding with the end cap of the guardrail. The vehicle rolled onto its right side, coming to rest in a ditch on the shoulder of the highway. Fortunately, the driver sustained only minor injuries.

Once on the scene, the responding trooper reported a light odor of propane. It was soon determined a cargo tank containing approximately 2,600 gallons of propane sustained extensive damage in the crash and was leaking. The cargo tank’s valving was also damaged, preventing the transfer of propane to another cargo tank.

HMRU troopers and specialists responded to the scene and evaluated the situation to mitigate the danger to the public. A coordinated response was developed to burn the propane using a flare stack to prevent a potential explosion of the cargo tank.

Wearing firefighter bunker gear for protection, HMRU troopers plugged the leaking valve and connected hoses from the cargo tank to the flare stack, strategically placed a safe distance away from the cargo tank. Troopers ignited the flare stack, allowing the propane to safely burn off and avoid an explosion from increased pressures inside the cargo tank. Cold temperatures caused the propane to burn at a slow rate, and the entire operation took four days until the cargo tank was rendered safe for removal.

On November 26, with all of the propane in the cargo tank safely burned off, the damaged vehicle was removed, and the highway was safely reopened. HMRU troopers worked multiple shifts to ensure the scene was rendered safe. Troopers assigned to the Globe area and emergency response personnel from the Arizona Department of Transportation, Tri-City Fire District, Action Towing, Matlock Propane Company, and Grave’s Propane Company assisted at the scene.

Within an hour of the conclusion of this four-day incident, the HMRU responded to another commercial vehicle leaking hazardous materials near Flagstaff.

Propane tanker turned over on passenger side next to a road
Highway milemarker sign in foreground, overturned vehicle in background
Tanker after being uprighted