Aboveground storage tanks (ASTs) are used to house a variety of liquids from waste water to petrochemicals. Because most ASTs house material that is flammable or toxic, the Federal government has enacted strict aboveground storage tank regulations to reduce or eliminate personnel injury or environmental contamination due to explosion or spilling.
Aboveground Storage Tank Regulations
AST – General Description
Aboveground storage tank regulations state that those storage tanks which house liquids and are aboveground, regardless of contents. Any AST which stores any liquid from petrochemicals to hazardous waste or other hazardous materials fall under this description.
Summary of Government Requirements
ASTs used for storing petrochemical products are regulated mainly under the aboveground storage tank regulations set forth in 40 CFR 112. The words “aboveground storage tank” are not used, rather “bulk storage container” is used. Bulk storage containers, as defined by 40 CFR 112, are any containers used to store oil. 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
- Oils storage prior to further commerce distribution
Bulk Storage Container Definition
Aboveground storage tank regulations define a bulk storage container as any container having a capacity of 55 gallons or more and can be aboveground, partially buried, bunkered, or totally buried. Bunkered tanks are considered ASTs under 40 CFR 112.
Bunkered Tank Definition: Any container constructed or placed in the ground by removing earth and recovering the tank in a way that breaks surrounding natural grade. Bunkered tanks my lie above grade and be covered with earth, sand, gravel, asphalt, or other material.
A storage tank is not permitted for oil storage unless it is compatible with the materials stored and the conditions of storage like pressure and temperature.
Secondary Containment Requirements
Pursuant to aboveground storage tank regulations, all AST installations are to be constructed so that secondary containment of stored liquids is provided for the entire contents of the largest single container and enough freeboard to contain precipitation.
Dikes are are to be impervious and able to contain any discharged petrochemicals. Typically dikes use containment curbs and pits, however an alternative drainage trench enclosure system arranged in such a way that discharge will be safely confined in facility catchment basin or holding pond.
ASTs are to be constructed or updated to avoid discharges in one of the following ways:
- Audible or visual high liquid level alarms at a continuously attended operation or surveillance station.
- Pump cut-off devices which stop liquid flow at 95%
- Direct communications between the container gauge and the pumping station using audible or code signals
- Fast response systems to determine tank liquid level – digital computers, telepulse, direcet vision gauges
Aboveground storage tank regulations require that internal heating coils control leakage by checking the steam return and exhaust lines from coils which discharge into open watercourses, or pass steam return or exhaust through settling tanks, skimmers, other separation or retention systems.
No drainage of rainwater, even uncontaminated, is to be allowed from the dike area into storm drains or discharges of effluents into open watercourses, lakes, or ponds near facilities unless:
The drainage of uncontaminated rainwater is not allowed from the diked area into a storm drain or discharge of an effluent into an open watercourse, lake, or pond, bypassing the facility treatment system unless the facility:
- Keeps bypass valves sealed
- Rainwater is routinely inspected for discharge
- Bypass valves are resealed after draining under supervision
- Adequate records of drainage are kept
AST Testing and Monitoring
In accordance with aboveground storage tank regulations, each container is to be regularly tested or whenever repairs are being made. Testing frequency and variety is based upon a container’s size and design.
Facilities are required to combine visual inspection with the following testing methods:
- Acoustic emissions
- Other non-destructive shell testing
In addition, comparison records are to 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.
To maintain correct operation, liquid level sensors are to be regularly tested. Additionally effluent treatment facilities are to be inspected regularly to detect systems malfunctions that could result in liquid discharge.
Field-constructed ASTs are to be evaluated for the risk of discharge or failure resulting from brittle fracture or or other major system breakdown if they undergo:
- Change in service
Mobile and Portable ASTs
Mobile and portable ASTs are to be placed in such a way as to prevent discharge. They must also have secondary containment with a capacity equal to the largest container and have enough freeboard to contain rainwater.
The aboveground storage tank regulations of 40 CFR 112 apply to:
- Petroleum and non-petroleum oil
- Animal fat, oil, and grease
- Fish and marine mammal oil
- Vegetable oil
These aboveground storage tank regulations also apply to owners or operators of on or offshore facilities which could be expected to discharge harmful quantities of oil into navigable U.S. waterways or shore lines.
Applicable facilities engage in:
Also, any and all activities under the Outer Continental Shelf Lands Act or the Deepwater Port Act of 1974 which store oil in:
- Aboveground containers
- Completely buried tanks
- Standby storage containers which are not permanently closed
- Bunkered, partially buried, or vaulted tanks
AST Hazardous Material Storage
EPA reporting guidelines apply to certain types and amounts of hazardous materials such as:
- Diesel fuel
Hazardous material regulations regarding material being stored or used at facilities are outlined in the Laboratories -> Hazardous Materials Storage section of the Facility Regulatory Tour.
AST regulation is the primary responsibility of states. These regulation requirements are generally found in the states’ environmental regulations and fire codes. States may require certain actions to be taken such as:
- Tank painting
- Pipe filling
- Color coding of a tank’s contents
- Alarm installation
To learn more about bulk fuel tank regulations, please visit our Fuel Tank Regulations page