5704.2.11.3 Depth and cover.

Excavation for underground storage tanks shall be made with due care to avoid undermining of foundations of existing structures. Underground tanks shall be set on firm foundations and surrounded with at least 6 inches (152 mm) of noncorrosive inert material, in accordance with the manufacturer's installation instructions.

5704.2.11.4 Overfill protection and prevention systems.

Fill pipes shall be equipped with a spill container of not less than 15-gallon (56.8 L) capacity and an approved overfill prevention system to automatically prevent overflow in accordance with NFPA 30 and FC 5704.2.9.4.

5704.2.11.5 Leak prevention.

Leak prevention for underground tanks shall comply with the requirements of FC 5704.2.11.5.1 and 5704.2.11.5.2.

5704.2.11.5.1 Inventory control.

Daily inventory records shall be maintained for underground storage tank systems.

5704.2.11.5.2 Leak detection.

Underground storage tank systems shall be provided with an approved method of leak detection from any component of the system that is designed and installed in accordance with NFPA 30. Leak detection systems shall be tested at the time of installation at the owner's risk by his or her representative before a representative of the department.

5704.2.11.6 Periodic tank and piping test.

Any underground single-walled flammable or combustible liquid storage tank existing prior to the effective date of this code that is not provided with a leak detection system meeting the requirements of FC 5704.2.11.5.2 shall be precision tested at least once every 5 years.

   Exception: Bulk plant and terminal tanks.