Any hazardous waste remaining in an empty container or an inner liner removed from an empty container is not subject to RCRA regulation (§261.7(a)). A container or inner liner removed from an empty container that has held hazardous waste is considered empty if all wastes have been removed using practices commonly employed to remove materials from that type of container (e.g., pouring, pumping, and aspirating); and
no more than 2.5 centimeters (1 inch) of residue remains on the bottom of the container; or inner liner
no more than 3 percent by weight of the total capacity remains in a container or inner liner if the container is less than or equal to 110 gallons in size; or
no more than 0.3 percent by weight of the total capacity of the container remains in the container or inner liner if the container is greater than 110 gallons in size (§261.7(b)(1)).
A container that has held a hazardous waste that is a compressed gas is empty when the pressure in the container approaches atmospheric (§261.7(b)(2)). A container or an inner liner removed from a container that has held an acute hazardous waste listed in Parts 261.31, 261.32, or 261.33 must be triple rinsed or cleaned by another method that has been shown to achieve equivalent removal (§261.7(b)(3)). Additional guidance on empty containers is available in the following documents:
Memo, Denit to Matis; September 20, 1993 (RCRA Online 13626)
Memo, Denit to Igli; July 28, 1993 (RCRA Online 11761)
Memo, Lowrance to Winwood; September 13, 1990 (RCRA Online 11559)
Memo, Horner to Johnson; May 20, 1985 (RCRA Online 12407)
Monthly Call Center Report Question; December 1984 (RCRA Online 12342)
Memo, Skinner to Klepitsch; November 28, 1984 (RCRA Online 11048)
Memo, Skinner to Shocklee; December 13, 1983 (RCRA Online 12161)
EPA recognizes that there may be cases where the residue in the bottom of a container is difficult or even impossible to measure due to the shape of the container (e.g., rounded bottoms) or due to the position of the opening of the container (47 FR 36092, 36093; August 18, 1982 (OSW-FR-82-050)). Therefore, EPA provides a weight alternative to the one-inch rule. There is a 3 percent weight alternative for containers less than or equal to 110 gallons in size, and a 0.3 percent weight alternative for containers greater than 110 gallons in size (§261.7(b)(1)(iii)).