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An aboveground storage tank (AST) is a tank whose entire surface area is completely aboveground. Also, the entire surface area of the tank (including the tank bottom) can be visually inspected (40 CFR 260.10).
An underground storage tank (UST), on the other hand, is a tank whose entire surface area is totally below the surface of and covered by the ground (40 CFR 260.10). Note that EPA underground storage tank regulations at 40 CFR part 280 define UST as “a tank (including piping) which has at least 10 percent of its volume underground.” USTs containing petroleum or hazardous substances are regulated by (40 CFR 280).
Scope
Unlike USTs that are covered under an entire section of regulations, in addition to select areas under the hazardous waste regulations, ASTs, at the federal level, are regulated in a somewhat piecemeal way. Consequently, it is necessary to look in several different places for AST requirements.
Concerning the storage of hazardous waste in ASTs, you must look in the hazardous waste regulations (Parts 260 through 268) to determine what is required. Parts 262, 264, and 265 of the Resource Conservation and Recovery Act (RCRA), Subtitle C, also impact ASTs as these requirements apply to hazardous waste generators and treatment, storage, and disposal facilities.
If you store oil in an AST, you may be regulated under the Spill Prevention, Control and Countermeasure (SPCC) regulations at 40 CFR Part 112. The SPCC regulations establish procedures to prevent the discharge of oil into navigable waters.
Some ASTs fall under OSHA requirements (29 CFR 1910.106) if they contain flammable or combustible liquids. The rules apply to liquids with flashpoints below 200° F. In this case, the objective of the regulations is to protect workers from fires, rather than protecting the environment from spills.
Regulatory citations
- 40 CFR 112 — Oil Pollution Prevention
- 40 CFR 260 — Hazardous Waste Management System: General
- 40 CFR 262 — Standards Applicable to Generators of Hazardous Waste
- 40 CFR 264 — Standards for Owners and Operators of Hazardous Waste Treatment, Storage, and Disposal Facilities
- 40 CFR 265 — Interim Status Standards for Owners and Operators of Hazardous Waste Treatment, Storage, and Disposal Facilities
- 40 CFR 268 — Land Disposal Restrictions
- 40 CFR 280 — Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST)
- 29 CFR 1910.106 — Flammable Liquids
- WI DATCP 93.010 to 93.880
Summary of requirements
The majority of regulations affecting ASTs are found at the state and local level. Check with your state and local agencies to see if there are more stringent AST requirements that you need to know about.
WI Department of Agriculture, Trade and Consumer Protection Petroleum/Hazardous Liquids Storage Tanks Overview: https://datcp.wi.gov/Pages/Programs_Services/PetroleumHazStorageTanks.aspx