The 241-Z Treatment and Storage Tanks are a liquid waste collection system containing tanks in separate covered concrete cells located below grade in the 241-Z Building. The 241-Z Treatment and Stroage Tanks are used for intermediate storage and pH adjustment of aqueous waste from the Plutonium Finishing Plant Complex. This closure plan focuses on the Resource Conservation and Recovery Act (RCRA) of 1976 components and areas, and on contamination resulting from RCRA operations. This closure plan proposes using the visually verifiable 'debris rule' (40 Code of Federal Regulations 268) performance standard of a 'clean debris surface' to achieve clean closure.