Waste Programs Division: Underground Storage Tanks: Leaking UST Investigations and Cleanups

The purpose of the Leaking Underground Storage Tank (LUST) program is to protect public health and the environment from releases of petroleum and other hazardous substances from USTs. The activities necessary to investigate, analyze and conduct cleanup activities that assure the protection of public health, welfare and the environment are considered “corrective actions” (A.R.S. § 49-1005 ). Generally, releases from regulated USTs are the regulatory responsibility of the ADEQ UST Corrective Action Section. NOTE: ADEQ does not regulate releases from unregulated USTs or above ground storage tanks.

There are several components of an effective LUST program including: leak prevention, corrective action and enforcement.

Leak Prevention: The UST program conducts inspections at UST facilities that focus on verifying leak detection equipment, spill containment, overfill protection, and operator training. UST inspectors are available to assist UST owners and operators with understanding the importance of system testing and maintenance activities that prevent releases from their UST systems. UST inspectors work closely with LUST staff and UST Division Support’s UST Coordination Unit to identify suspected releases. The UST Coordination Unit provides compliance assistance to UST owners and operators about what is required to confirm a suspected release and the requirements of an initial response to a confirmed release.

Corrective Action: The LUST program provides compliance assistance and regulatory oversight for UST owners and operators who have had a release from their UST system. The program also assists property owners who voluntarily undertake corrective actions (these activities are often related to property re-development). Additionally, for those who qualify under A.R.S. § 49-1017, the State Lead program is available to provide direct project management and contracting.

Enforcement: If the UST owner and operator fail to conduct adequate corrective action for their UST release within time frames required by federal and state regulations, the Leaking Underground Storage Tank Enforcement Unit (LEU) may initiate enforcement actions against them.

What is a "Leaking UST"?

An underground storage tank (UST) that has had a release of a regulated substance (typically petroleum) is called a “leaking UST” or a “LUST.” This designation does not mean that the UST system continues to leak, it means that a release occurred. Even with upgrade requirements and improvements in leak prevention, some UST systems will have a release.

Under A.R.S. § 49-1001(17):"Release" means a spill, leak, emission, discharge, escape, leach or disposal of a regulated substance from an underground storage tank into groundwater, surface water or soils.

There are strict regulatory requirements for how an owner and operator must respond to a suspected and confirmed release from their UST system.

Must all LUST releases be investigated and cleaned up?

All LUST releases are required to be investigated to determine the extent and degree of contamination. If the level of contamination is considered a risk, the owner and operator are required to conduct corrective actions to address this risk.

Why is the LUST program important?

Leaking USTs may present safety and environmental risks including the potential for fire and explosion. Millions of gallons of petroleum products and hazardous substances are stored in USTs in the U.S. and leaking USTs have been identified as a major source of soil and groundwater contamination. EPA and state UST regulations are designed to reduce the risk of and address underground leaks to minimize environmental harm and keep the costs of major cleanups down.

Releases from LUSTs may create a risk to soil, groundwater and surface water (drinking water resources) and air (through vapor intrusion). Contamination from the release may require extensive and expensive cleanup efforts (which is why UST owners and operators are required meet Financial Responsibility Requirements.

When a LUST release is discovered, the owner or operator must report the release to ADEQ, mitigate immediate threats, investigate the extent of contamination and implement a plan of corrective action to address the risks.


!UST owners and operators are required to notify ADEQ within 24 hours of a release or suspected release of an underground storage tank. Call (602) 771-4289 to speak with a UST program representative. You may also call ADEQ toll free at (800) 234-5677 extension 771-4289.

Helpful Links

Bulletins Risk-Based Corrective Action
Honeywell 34th St. Facility Site Update November 2008 (en español) UST/LUST Stakeholder Meetings
LUST Database Search

See Also:


UST/LUST Stakeholder Meetings

A series of stakeholder meetings took place in 2014 to discuss the proposed new framework for the Underground Storage Tank Program (UST) as mandated by two recent legislative bills signed into law by Governor Jan Brewer.

The stakeholders were comprised of UST owners and operators, insurance companies, local insurance agents and brokers, and petroleum marketers.

“Over the course of the next few weeks ADEQ will be reaching out to stakeholders most affected by these upcoming changes,” said ADEQ Director Henry Darwin. “We need a productive discussion about creating a sustainable UST Program that will benefit all Arizonans.”

The first bill, House Bill 2708, prohibits delivery of fuel to USTs that cannot demonstrate financial responsibility obligations. The bill also includes the proposed new framework for the UST program, including the development of standard Arizona-specific UST insurance.

Senate Bill 1314 allows owners or operators to forego a baseline site assessment and the standard Arizona specific policy legislated by HB 2708 if they can demonstrate that they meet federal and state financial responsibility requirements.

The State Assurance Fund (SAF), a one-cent per gallon excise tax on motor fuel, was established by the Legislature in 1990 to help ADEQ and UST owners and operators offset the high cost of cleanups. But that funding stopped two years ago.

An actuarial analysis of the proposed new UST program was recently completed by Taylor and Mulder and is available here.

UST/LUST Stakeholder Meeting Information
Meeting Date (all in 2014) Documentation
November 6 UST/LUST Program Options PresentationSign-In SheetMeeting SummaryAPMA Comments on ADEQ UST/LUST Program Options Program Options Feedback
September 25 Laura Malone's PresentationDaniel Lupton's PresentationVideo of the MeetingSign-In SheetSummary
July 28 Program PresentationSign-In SheetSummary

Subscribe to our email notification (listserv) to be notified of UST related information or subscribe to other ADEQ lists.

Back to the top of the page


Risk-Based Corrective Actions

Under Arizona § 49-152, the final soil rule was promulgated and became effective on Dec. 4, 1997. This rule allows remediation of contaminated site soils to background, the predetermined remediation standards (SRLs), or site-specific remediation standards. In conjunction with this rule, ADEQ's Underground Storage Tank Program has promulgated the corrective action and release reporting rules , which include the tiered risk-based corrective actions (RBCA) approach to decision making for determining current or potential risk at a site and the corrective actions needed to remediate to an acceptable level of risk.

The UST Program has implemented the RBCA rules, and is in the process of updating RBCA guidance documents.