(b) The permittee must prepare a post-closure monitoring and maintenance plan which must be approved by the department. Post-closure monitoring and maintenance must be performed in accordance with the post-closure plan approved by the department as required by Subparts 383-3 and 383-5 of this Part. The post-closure plan must include:

1. (1) a detailed description of all post-closure monitoring and maintenance activities including:

   1. (i) provisions for environmental monitoring based on the operating history of the land disposal facility and the site closure and stabilization measures and in accordance with the requirements of Subpart 383-10 of this Part;
   2. (ii) provisions for structural monitoring based on the operating history of the disposal units and the disposal unit closure measures; and
   3. (iii) provisions for any maintenance of the disposal units that may become necessary;
2. (2) a detailed schedule for the post-closure monitoring and maintenance activities; and

3. (3) a detailed estimate of the cost of implementing the post-closure plan.

   (c) Annual revision of the post-closure plan.

4. (1) The permittee must annually revise the post-closure plan and submit it to the department for approval no later than 90 days prior to the anniversary date of the issuance of the permit, except in the year when the permit expires. In the year the permit expires, the permittee must submit a revised post-closure plan as part of the permit renewal application.

5. (2) The revised plan must take into account relevant new information including the following:

   1. (i) proposed changes in the design of the land disposal facility;
   2. (ii) changes in the volumes, classes, specific activity, or other characteristics of the waste estimated to be disposed of at the land disposal facility;
   3. (iii) any additional geologic, hydrologic, or other site data pertinent to the long-term containment of waste obtained during the operation period;
   4. (iv) the results of the monitoring required by Subpart 383-10 of this Part and any other tests, experiments, or analyses performed by the permittee that are pertinent to the long-term containment of waste within the disposal units;
   5. (v) any proposed revisions to the closure plan that would affect the post-closure plan; and
   6. (vi) changes in the estimated cost of implementing the post-closure plan.
6. (3) Within 30 days following the receipt of the revised post-closure plan, the department will review the revised post-closure plan and approve it or provide the permittee with a written statement of the reasons why the department will not approve it. In the event that the revised post-closure plan is not approved, the permittee must correct the deficiencies and re-submit the revised post-closure plan within 30 days of the date of the department's written statement of disapproval.