2306.2.1.1 Inventory Control and Leak Detection for Underground Tanks

Accurate inventory records shall be maintained on underground fuel storage tanks for indication of possible leakage from tanks and piping. The records shall be kept at the premises or made available for inspection by the fire official within 24 hours of a written or verbal request and shall include records for each tank. Where there is more than one system consisting of tanks serving separate pumps or dispensers for a product, the inventory record shall be maintained separately for each tank system.

Owners and operators of underground fuel storage tanks shall provide release detection for tanks and piping that routinely contain flammable and combustible liquids in accordance with one of the following methods:

1. Monthly inventory control to detect a release of at least 1.0 percent of flow-through plus 130 gallons (492 L).
2. Manual tank gauging for tanks with 2,000-gallon (7570 L) capacity or less when measurements are taken at the beginning and ending of a 36-hour to 58-hour period during which no liquid is added to or removed from the tank.
3. Tank tightness testing capable of detecting a 0.1-gallon (.3785 L) per hour leak rate.
4. Automatic tank gauging that tests for loss of liquid.
5. Vapor monitoring for vapors within the soil of the tank field.
6. Groundwater monitoring when the groundwater is never more than 20 feet (6096 mm) from the ground surface.
7. Interstitial monitoring between the underground tank and a secondary barrier immediately around or beneath the tank.
8. Other approved methods that have been demonstrated to be as effective in detecting a leak as the methods listed above.

A consistent or accidental loss of product shall be immediately reported to the fire official.