Section 30.661 - Applicability(1) Except as provided in 310 CMR 30.661(2) and (3), 30.661 through 30.673, cited collectively as 310 CMR 30.660, prescribe requirements which apply to owners and operators of regulated units that receive hazardous waste after July 26, 1982. As used in 310 CMR 30.660, the term "regulated unit" shall mean a surface impoundment, waste pile, miscellaneous units, land treatment unit or landfill which treats, stores or disposes of hazardous waste. Any hazardous waste or hazardous waste constituent found beyond a waste management area described in 310 CMR 30.669(2) shall be presumed to originate from a regulated unit unless the Department determines that such waste or waste constituent originated from another source.(2)310 CMR 30.660 shall not apply to a waste pile that is designed and operated in compliance with 310 CMR 30.640(4).(3) The requirements in 310 CMR 30.660 apply during the active life of each regulated unit and during the closure period for each regulated unit. After closure of each regulated unit, 310 CMR 30.660 shall:(a) Apply during the post-closure period pursuant to 310 CMR 30.590 through 30.595 if the owner or operator is conducting a detection monitoring program pursuant to 310 CMR 30.664;(b) Apply during the compliance period specified in 310 CMR 30.670 if the owner or operator is conducting a compliance monitoring program pursuant to 310 CMR 30.671 or a corrective action program pursuant to 310 CMR 30.672.(c) Not apply if all hazardous waste, hazardous waste residues, contaminated containment system components, and contaminated subsoils are removed or decontaminated during closure, unless 310 CMR 30.661(3)(b) applies;(d) Not apply if the Department determines, pursuant to 310 CMR 30.659(4), that: 1. The treatment zone of a land treatment unit does not contain levels of hazardous constituents that, by amounts that are statistically significant, are above background levels of those constituents; and2. The unsaturated zone monitoring program done in compliance with 310 CMR 30.655 has not shown a statistically significant increase in hazardous constituents below the treatment zone during the operating life of the land treatment unit.(4) The Department may waive any requirement of 310 CMR 30.660 otherwise applicable to a miscellaneous unit if the Department is persuaded that, as applied to that miscellaneous unit, the requirement is unnecessary to protect public health, safety or welfare or the environment.