Underground Storage Tanks (USTs)

Secondary Containment and Under-Dispenser Containment - 2015 Requirements

In 2015, EPA revised the underground storage tank (UST) regulations.

Secondary Containment

Beginning on April 11, 2016 owners and operators must install secondarily contained tanks and piping when installing or replacing tanks and piping. Owners and operators must use interstitial monitoring as release detection for these new or replaced tanks and piping. Automatic line leak detectors are still required for new and replaced pressurized piping.

  • Secondary containment means the tank and piping have an inner and outer barrier with an interstitial space that is monitored for leaks and includes containment sumps when those sumps are used for interstitial monitoring of the piping.
  • Replaced for a tank means to remove a tank and install another tank.
  • Replaced for piping means to remove 50 percent or more of piping and install other piping. Piping does not include the connectors used to connect the piping to the tank or dispenser. This definition applies to each piping run connected to a single tank. Owners and operators of tanks with multiple piping runs must apply this definition independently to each piping run.
  • Owners and operators do not have to meet the secondary containment requirement for new or replaced piping under the following conditions:
    • piping is European or safe suction piping
    • piping is associated with airport hydrant systems
    • piping is associated with field-constructed tanks greater than 50,000 gallons in size

Under-Dispenser Containment (UDC)

Beginning on April 11, 2016 owners and operators must install under-dispenser containment for all new dispenser systems.

  • A dispenser system is considered new when both the dispenser and the equipment needed to connect the dispenser to the UST system are installed at an UST facility. Examples of equipment needed to connect the dispenser to the UST system include check valves, shear valves, unburied risers, flexible connectors or other transitional components underneath the dispenser which connect the dispenser to the underground piping.
  • Under-dispenser containment or UDC is containment underneath the dispenser system designed to prevent leaks from the dispenser and piping within or above the UDC from reaching soil or groundwater. UDC must be liquid-tight on its sides, bottom, and at any penetrations. It must allow for visual inspection and access to the contained components or be periodically monitored for leaks from the dispenser system.
  • A dispenser is the equipment located aboveground that dispenser regulated substances from the UST system.
  • A dispenser system includes the dispenser and the equipment necessary to connect the dispenser to the UST system.