Aboveground Storage Tanks & Regulations

AST (above-ground storage tank) – General Regulations

Aboveground storage tank regulations apply to tanks that store liquids and are located aboveground, regardless of their contents. Any AST storing liquids, from petrochemicals to hazardous waste or other hazardous materials, falls under this category. You can also view regulations by state.

Summary of Government Requirements

ASTs used for storing petrochemical products are regulated primarily under the aboveground storage tank regulations set forth in 40 CFR 112. Instead of the term “aboveground storage tank,” “bulk storage container” is used. According to 40 CFR 112, bulk storage containers are any containers used to store oil. However, oil-filled electrical, operating, or manufacturing equipment is not classified as a bulk storage container.

Storage Container Purposes

• Oil storage prior to use
• Oil storage during use
• Oil storage prior to further commercial distribution

Bulk Storage Container Definition

Aboveground storage tank regulations define a bulk storage container as any container with a capacity of 55 gallons or more. It can be aboveground, partially buried, bunkered, or totally buried. Bunkered tanks are considered ASTs under 40 CFR 112.

Bunkered Tank Definition

A bunkered tank is any container constructed or placed in the ground by removing earth and then covering the tank in such a way that it breaks the surrounding natural grade. Bunkered tanks may lie above grade and be covered with earth, sand, gravel, asphalt, or other materials.

Design

A storage tank is permitted for oil storage only if it is compatible with the materials stored and the conditions of storage, such as pressure and temperature.

Secondary Containment Requirements

According to aboveground storage tank regulations, all AST installations must be constructed to provide secondary containment for the entire contents of the largest single container, with sufficient freeboard to contain precipitation.

Dikes must be impervious and capable of containing any discharged petrochemicals. Typically, dikes use containment curbs and pits. However, an alternative drainage trench enclosure system can be arranged in such a way that any discharge will be confined safely in a facility’s catchment basin or holding pond.

Leakage Management

Drainage

Aboveground storage tank regulations require that internal heating coils control leakage by checking the steam return and exhaust lines from coils. These lines should not discharge into open watercourses, or alternatively, the steam return or exhaust should pass through settling tanks, skimmers, or other separation or retention systems.

The drainage of uncontaminated rainwater from the diked area into storm drains or discharges of effluents into open watercourses, lakes, or ponds near facilities is prohibited, unless the facility:

• Keeps bypass valves sealed
• Routinely inspects rainwater for contamination before discharge
• Reseals bypass valves after draining under supervision
• Maintains adequate records of drainage

AST Testing and Monitoring

In accordance with aboveground storage tank regulations, each container must be regularly tested, especially when repairs are being made. The frequency and type of testing depend on a container’s size and design.

Inspection Rules

Facilities must combine visual inspection with testing methods such as hydrostatic, radiographic, ultrasonic, acoustic emissions, and other non-destructive shell testing. Furthermore, comparison records should be retained for reference to past inspections. Container supports, foundations, and exteriors must also be regularly inspected for deterioration, discharges, or oil accumulation within dike areas.

Mobile and Portable ASTs

Mobile and portable ASTs must be placed to prevent discharge. They must also have secondary containment with a capacity equal to the largest container and enough freeboard to contain rainwater.

Regulation Applicability

The aboveground storage tank regulations of 40 CFR 112 apply to a wide range of oils and facilities engaged in various activities related to oil storage and handling.

AST Hazardous Material Storage

EPA reporting guidelines apply to certain types and amounts of hazardous materials such as gasoline, diesel fuel, and chemicals. These regulations are outlined in the Laboratories -> Hazardous Materials Storage section of the Facility Regulatory Tour.

State Requirements

AST regulation is primarily the responsibility of states. These requirements are usually found in the states’ environmental regulations and fire codes. States may require actions such as tank painting, pipe filling, color coding of tank contents, and alarm installation.