Section 30.659 - Closure and Post-Closure Care(1) During the closure period of the land treatment facility, the owner or operator shall: (a) Continue all operations (e.g., pH control) necessary to maximize degradation, transformation, and immobilization of hazardous constituents within the treatment zone as required by 310 CMR 30.654(2), except to the extent such measures are inconsistent with 310 CMR 30.659(1)(h);(b) Continue all operations in the treatment zone to minimize runoff of hazardous constituents, as required by 310 CMR 30.654(5);(c) Maintain the run-off management system required by 310 CMR 30.654(6).(d) Maintain the run-on control system required by 310 CMR 30.654(7);(e) Control wind dispersal of hazardous waste if required by 310 CMR 30.654(9);(f) Continue to comply with the prohibition on growing food chain crops as set forth in 310 CMR 30.654(11);(g) Continue unsaturated zone monitoring in compliance with 310 CMR 30.655 except that soil-pore liquid monitoring may be terminated 90 days or more after the last application of waste to the treatment zone; and(h) Establish a vegetative cover on the portion of the land treatment unit being closed at such time that the cover will not substantially impede degradation, transformation or immobilization of hazardous constituents in the treatment zone. The vegetative cover shall be capable of maintaining growth without extensive maintenance.(2) For the purpose of complying with 310 CMR 30.587, when closure of the land treatment facility is completed, the owner or operator may submit to the Department certification by an independent qualified soil scientist, in lieu of an independent Massachusetts registered professional engineer, that the land treatment facility has been closed in compliance with the specifications in the approved closure plan.(3) During the post-closure care period the owner or operator shall: (a) Continue all operations (e.g., pH control) necessary to maximize degradation and transformation and sustain immobilization of hazardous constituents in the treatment zone to the extent that such measures are consistent with other post-closure activities;(b) Maintain a vegetative cover over closed portions of the land treatment unit;(c) Maintain the run-on control system required by 310 CMR 30.654(7);(d) Maintain the run-off management system required by 310 CMR 30.654(6);(e) Control wind dispersal of hazardous waste if required by 310 CMR 30.654(9);(f) Continue to comply with the prohibition concerning growth of food-chain crops as set forth in 310 CMR 30.654(11); and(g) Continue unsaturated zone monitoring in compliance with 310 CMR 30.655, except that soil-pore liquid monitoring may be terminated 90 days or more after the last application of waste to the treatment zone.(4) An owner or operator need not comply with 310 CMR 30.659(1)(h) and (3) if the Department determines that the level of hazardous constituents in the treatment zone soil does not exceed the background value of those constituents by an amount that is statistically significant when using the test specified pursuant to 310 CMR 30.659(4)(c). The owner or operator may submit such a demonstration to the Department at any time during the closure or post-closure care periods. For this purpose: (a) The owner or operator shall establish background soil values and determine whether there is a statistically significant increase over those values for all hazardous constituents specified in the land treatment license pursuant to 310 CMR 30.652(2). 1. Background soil values may be based on a one-time sampling of a background plot that is on the site and that has characteristics similar to those of the treatment zone. The Department shall specify the number of samples to be taken, which number shall be no less than three.2. The owner or operator shall express background values and values for hazardous constituents in the treatment zone in a form suitable for the determination of statistically significant increases pursuant to 310 CMR 30.659(4)(c).(b) In taking samples used in the determination of background soil values and treatment zone values, the owner or operator shall take samples at a sufficient number of sampling points and at appropriate locations and depths to yield samples that represent the chemical makeup of:1. soil that has not been affected by leakage from the treatment zone; and2. soil within the treatment zone.(c) In determining whether a statistically significant increase has occurred, the owner or operator shall compare the value of each constituent in the treatment zone to the background value for that constituent using a statistical procedure that: 1. Provides reasonable confidence that constituent presence in the treatment zone will be identified.2. Is appropriate for the distribution of the data used to establish background values;3. Provides a reasonable balance between the probability of falsely identifying the presence of hazardous constituents in the treatment zone and the probability of failing to identify real presence of hazardous constituents in the treatment zone; and4. Is approved, in writing, by the Department.(5) The owner or operator need not comply with 310 CMR 30.660: Groundwater Protection if the Department finds that the owner or operator meets the requirements of 310 CMR 30.659(4) and if unsaturated zone monitoring required by 310 CMR 30.655 indicates that hazardous constituents have not migrated beyond the treatment zone during the active life of the land treatment unit.