What is an Oil Tank Farm?
An oil tank farm, or tank farm, is a common term for an oil depot or oil terminal, an industrial facility dedicated to storing oil, petroleum and petrochemical materials. Tank farms or liquid bulk terminals are usually equipped for the loading and transfer of fuel products and feature above ground or underground tanks, pipelines, pumping facilities and additional transfer equipment to load tanker trucks, trains or barges.
How Do Oil Depots Operate?
Some oil depots are constructed as part of oil refineries or placed in close proximity to them. Coastal oil terminals include shore tanks for marine transfer operations. They can receive fuel discharged from oil tankers for storage followed by transfer to pipelines or transportation vehicles. In addition to the storage tanks, depots have loading areas constructed with fuel loading/unloading racks, platforms, gangways, loading/unloading arms and other equipment to ensure the safe transfer of fuel.
What Are the Containment Requirements for On-Shore Fuel Storage Tanks?
Containment requirements for on-shore fuel storage tanks at oil tank farms generally overlap with the specifications for above ground storage tanks (ASTs). The Spill Prevention, Control and Countermeasure (SPCC) requirements of the U.S. Environmental Protection Agency were introduced to protect waterways and the surrounding environment from leaks or spills. These apply to facilities with total AST capacity of more than 1,320 gallons in containers of 55 gallons or larger, or total buried capacity of more than 42,000 gallons.
The Institute for Electrical and Electronics Engineers (IEEE) also sets a standard for containment and control of oil spills. Other relevant regulations include the Occupational Health and Safety Act (OSHA) requirements for flammable and combustible liquids as well as international, national and local codes for fires.
SPCC regulations include general and specific secondary containment requirements. All facilities must meet the general requirements, which address potential oil leaks, spills and discharges. Examples of requirements include facility construction features such as impervious berms or retaining walls, gutters, retention ponds or other drainage systems, the supply of sorbent materials to recover liquids, barriers such as skim mats and collection systems such as sumps.
Bulk storage tanks and containers must also meet the specific requirements (also called “sized secondary containment requirements”), which address major tank or container failures.
Secondary Containment Solutions for Oil Terminal Tanks
Tank farm design guidelines require secondary containment systems, which go into effect when the primary containment has failed.
The EPA’s hazardous waste storage regulation 40 CFR 264.175 requires that secondary containment systems be impervious, free of gaps or cracks and chemically compatible with the material being stored. The exterior of the containers, including tank supports and foundations, must receive regular visual inspections for signs of leaks, damage and deterioration. The integrity of the container should also receive regular hydrostatic, radiographic, ultrasonic, acoustic emissions testing or other nondestructive shell thickness testing.
The containment system must have either a sloped design or a means for quick removal of leaking or spilled material. It must have capacity to contain at least 10 percent of the total volume of the primary container or 100 percent of the volume of the largest container, whichever is larger. The system must either prevent precipitation such as rainwater or run-on from entering or have capacity to accommodate potential precipitation from a 24-hour, 25-year storm.
Material leaked or spilled into the secondary containment area must be removed as quickly as possible to avoid overflow and potential environmental contamination.
Regulations for loading areas may require secondary containment made of impermeable material that can accommodate the maximum capacity of any compartment of the tank car or tank truck. The area must have signs or barriers to prevent premature vehicle movement that could cause a spill and be maintained under conditions that will not interfere with the containment system.
In addition, fuel storage tanks in the United States must be protected from corrosion, particularly metal tanks in contact with soil containing petroleum products. A liner on the internal walls and floor can prevent contact between the metal shell and accumulated water or sediment.
Oil tank farm containment can have longer life and greater durability when used with such products as spray coatings or liners to protect the surface of the containers and prevent fuel leaks and spills.