Hazardous waste listings apply retroactively to wastes land disposed prior to the effective date of the listings (57 FR 37284, 37298; August 18, 1992). All wastes meeting the listing description are hazardous regardless of when they were disposed. The time at which a waste was disposed does not affect whether or not it meets the listing description (53 FR 31138, 31147; August 17, 1988). This does not mean that such wastes must be exhumed for proper treatment. Hazardous wastes are subject to Subtitle C controls only when they are actively managed (57 FR 37298). EPA defines active management as physically disturbing accumulated wastes within a management unit or disposing of additional hazardous wastes in existing units containing previously disposed wastes (54 FR 36592, 36597; September 1, 1989).
Additional guidance on the concept of active management is available in the following memos:
Memo, Lowrance to Goodwin; April 26, 1993 (RCRA Online 13602)
Memo, Lowrance to Green; June 11, 1992 (RCRA Online 11671)
Memo, Cannon to Simon; June 26, 1989 (RCRA Online 11436)
Memo, Skinner to Davine; August 17, 1983 (RCRA Online 11029) [Adobe PDF 6.5K]