If an AST is "empty", is that still an AST?
Yes, unless they are closed in a specific manner. If an aboveground storage tank is “empty” but will still or can readily be used to store a petroleum product (usually the same product that it previously contained), then this “empty” AST is still considered an AST, and is regulated under APSA. However, if the “empty” AST container meets the federal SPCC rule definition of “permanently closed”, it is not captured under APSA.
“Permanently closed,” as defined in 40 CFR 112.2, refers to containers “for which (1) All liquid and sludge has been removed from each container and connecting line; and (2) All connecting lines and piping have been disconnected from the container and blanked off, all valves (except for ventilation valves) have been closed and locked, and conspicuous signs have been posted on each container stating that it is a permanently closed container and noting the date of closure.
If the AST can and will no longer be used to store a petroleum product, that AST is no longer subject to APSA, but the AST must be completely emptied, cleaned of all petroleum residuals, and completely physically disconnected from all petroleum-containing piping.
The SPCC plan should be updated as necessary to reflect the status of all regulated tanks.