UST Compliance

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Underground storage tanks (UST’s) registered with NC Department of Environment and Natural Resources are required to be inspected by Division of Waste Management UST Section. The goal of the compliance inspections is to protect human and the environment from release from UST’s.  The regulations require owners and operators to prevent releases, detect releases, and correct problems caused by releases. An inspection of your UST system and a review of your records will find and help you correct and deficiencies to ensure that human and health and the environment is protected and to fulfill the state and EPA requirements. Owners and operators are equally responsible for complying with all applicable UST regulations. Compliance inspections for the past 12 months in North Carolina indicated less than half the facilities inspected are in compliance.

A UST system consists of the underground storage tank, all associated piping and ancillary equipment (e.g. flex connectors, submersible pumps, pipe joints, etc.), and the dispenser (gas pump). Tank owners are required to pay tank fees for their registered tanks even if the tanks are in TEMPORARY closure. The fees are part of the owner’s financial responsibility requirements in case of a leak from the system.

Information and current status for any active UST systems installed in Guilford County can be obtained by visiting Guilford County GIS web site.

Operating permit: NC General Statute requires a UST facility to have a current operating permit to receive fuel deliveries. If a facility does not have a current permit then a fuel deliverer cannot deliver any fuel to the UST system.  A facility will not be issued a operating permit for following reasons: incorrect mailing address, failure to pay tank fees, improper completion of the forms, insufficient proof of ownership, insufficient proof of financial responsibility, and/or compliance violation.

Overfill Protection: All regulated UST systems are required to have overfill devices to ensure that petroleum or hazardous material are not released to the environment while filling UST’s. The overfill protection includes a flapper valve, a overfill alarm, and a ball float valve. The flapper valve will shut off filling operation at 95%of the UST’s capacity. The overfill alarm works in conjunction with automatic gauge system to provide a visual and audible alarm when the tank reaches 90% of the UST’s capacity or within one minute of being overfilled. The ball valve is installed at the tanks vent pipe to restrict UST’s vapor flow. It works on the principle that as the tank fills, the ball in the valve rises to restrict vapor flow. Once activated it will slow the product delivery by increasing the vapor pressure in the tank. 

Spill Bucket: The fill port of each UST system must have a spill bucket free of holes or defects and free of water, fuel, and debris. It should be clean and dry at all times. The spill bucket is not made to hold product for extended period of time. If there are holes in the bucket, the UST system has a release to the environment.

Piping System Types: The UST’s piping system is either pressurized or suction piping. Release from piping systems are one of primary sources of contamination from UST system.  Pressurized piping must have an automatic line detector capable of detecting a release of 3.0 gallons per hour. If the leak detector is mechanical it must be tested annually. If the detector is electronic it must also be tested annually unless the manufacturer states the unit performs an automatic functional self-test. Suction piping for some new systems has only one check valve under the dispenser pump (also known as safe suction or European suction). While most check valves are readily visible, those encased in a union may not be. If there is a check valve under the dispenser, and no other check valve in the line, no additional leak detection is required  if the piping operates at less than atmospheric pressure and is sloped so the pipe contents drain into the tank when suction is released. 


Sitting and secondary Containment: UST systems are required to be sited at certain distance from wells and specified surface waters. 

  • No regulated UST system (including tank, piping and dispensers) may be installed within 100 feet of the public water supply well. Regulated UST systems may be installed between 100 and 500 feet of public water supply well, but secondary containment (double-walled UST systems with interstitial monitoring) is required.  

  • No regulated UST system (including tank, piping and dispensers) may be installed within 50 feet of any other well used for human consumption. Regulated UST systems may be installed between 50 and 100 feet of any other well used for human consumption, but secondary containment (double-walled UST systems with interstitial monitoring) is required.

All UST systems installed on or before January 1, 1991 that met “new tank system” performance standards (corrosion protection, spill prevention and overfill prevention) by that date are exlcuded from these siting and secondary containment regulations.

Sitting and secondary Containment Update Schedule: Secondary containment must be installed by January 1st of the following years: 

  • 2005 for all steel or metal connected piping and ancillary equipment (e.g. flex connectors, submersible pumps, pipe joints, etc.).

  • 2008 for all fiberglass or non-metal connected piping and ancillary equipment.

  • 2008 for all USTs installed on or before January 1, 1991.

  • 2016 for all USTs installed after January 1, 1991.

Suspected Release: Evidence of a suspected release includes product present in containment sumps, stained soil from an overfill, and/or any growth of the piping or other unusual conditions. Evidence of a release requires that the release be reported and investigated. Release that are 25 gallons or greater must be reported and cleaned up. Owners and/or operators may not know that must report releases less than 25 gallons which cannot be cleaned up within 24 hours.