At closure of a containment building, the owner or operator shall: Remove or decontaminate all waste residues, contaminated system components such as liners, contaminated subsoils, and structures and equipment contaminated with waste and leachate; and Manage the removed materials and wastes generated in performing decontamination as hazardous waste unless COMAR 26.13.02.03D applies. The owner or operator shall assure that the closure plan, closure activities, cost estimates for closure, and financial responsibility for containment buildings meet all of the requirements specified in Regulations .07 and .08 of this chapter. If, after removing or decontaminating all residues and making all reasonable efforts to effect removal or decontamination of contaminated components, subsoils, structures, and equipment as required in §A of this regulation, the owner or operator finds that not all contaminated subsoils can be practicably removed or decontaminated: The owner or operator shall close the facility and perform post-closure care in accordance with the closure and post-closure requirements that apply to landfills in Regulation .14J of this chapter; and For the purposes of closure, post-closure, and financial responsibility, the containment building is then considered to be a landfill, and the owner or operator shall meet all of the requirements for landfills specified in Regulations .07 and .08 of this chapter.