1. Owners and operators of hazardous waste facilities shall submit to the department for its approval plans for the closure and post-closure monitoring and maintenance of their facilities. The department may promulgate rules and regulations concerning the contents of such plans. Such regulations shall reflect due consideration of relevant federal requirements and except where necessary to serve the public interest or inconsistent with the purposes of this section, shall conform to relevant federal regulations, but shall in no case be less stringent than such federal requirements and regulations. In the case of new facilities, such plans shall be approved prior to the effective date of the facility's operating permit. In the case of existing facilities, such plans shall be submitted to the department within six months of the effective date of this section, and shall be approved, denied or modified by the department within twelve months of submission.

2. Together with the submission of a plan for closure and post-closure monitoring and maintenance, the owner or operator of a hazardous waste facility shall submit to the department for approval a written estimate of the costs associated therewith. The estimate of closure costs must equal the cost of closure at the point in the facility's operating life when the extent and manner of its operation would make closure the most expensive, as indicated by its closure plan.

3. The owner or operator shall prepare new closure and post-closure monitoring and maintenance cost estimates whenever the department or the owner or operator determines that a change in either the closure or post-closure monitoring and maintenance requirements affects the cost of closure or post-closure care respectively.

4. One year after the approval of the cost estimates as set forth in subdivision two of this section, and annually thereafter until closure of the facility, the owner or operator shall adjust the closure and post-closure monitoring and maintenance estimates to account for inflation.

5. All estimates made pursuant to this section and revisions thereto shall be subject to the review and approval of the department.

6. The department shall periodically review the methods and instruments of financial assurances for permitted hazardous waste facilities to determine whether they are adequate in light of changed circumstances to insure proper closure and post-closure monitoring and maintenance of such facilities.

7. The provisions of this section relating to post-closure monitoring and maintenance plans and cost estimates associated therewith shall only apply to owners and operators of disposal facilities.