Waste Programs Division
What is an Underground Storage Tank?
An underground storage tank (UST) system is a tank and any underground piping connected to the tank that has at least ten percent of its combined volume underground. Federal and state UST regulations apply only to underground tanks and piping storing either petroleum or certain hazardous substances.
ADEQ's Waste Programs Division ensures proper operation and maintenance of regulated underground storage tank systems by conducting periodic inspections and assisting owners and operators in complying with applicable state and federal regulations. Enforcement actions are taken in cases of significant non-compliance. The division also protects public health and the environment through oversight, investigation and cleanup of soil and groundwater contamination caused by releases from underground storage tanks.
The UST Program regulates the majority of USTs in Arizona with the exception of those on Indian country. Nearly all underground storage tanks at these site contain petroleum.1 These sites include marketers who sell gasoline to the public (such as service stations and convenience stores) and non-marketers who use tanks solely for their own needs (such as fleet service operators and local governments).
Do you know if your UST(s) are regulated? | Learn more about regulated USTs
1Under Arizona Revised Statutes (ARS) § 49-1001: "Petroleum" means petroleum, including crude oil or any fraction of crude oil, which is liquid at 60 degrees Fahrenheit and 14.7 pounds per square inch absolute, and petroleum based substances comprised of a complex blend of hydrocarbons derived from crude oil through processes of separation, conversion, upgrading and finishing, such as motor fuels, residual fuel oils, lubricants, jet fuels, distillate fuel oils, petroleum solvents and used oils.