Section 30.617 - Closure and Post-Closure Care(1) At closure of a new surface impoundment, the owner or operator shall remove or decontaminate all waste residues, contaminated containment system components (e.g., liners), contaminated subsoils, and structures and equipment contaminated with waste or leachate, and manage them as hazardous waste unless 310 CMR 30.141 applies.(2) At closure of an existing surface impoundment, either:(a) The owner or operator shall remove or decontaminate all waste residues, contaminated containment system components (e.g., liners), contaminated subsoils, and structures and equipment contaminated with waste or leachate, and manage them as hazardous waste unless 310 CMR 30.141 applies; or(b) If the Department determines that it will be impracticable for the owner or operator to comply with 310 CMR 30.617(2)(a), the Department may approve an alternate closure plan which requires the owner or operator to do the following at closure:1. Remove wastes, waste residues, contaminated equipment and soils to the extent practicable;2. Eliminate free liquids by either removing liquid wastes or solidifying the remaining wastes and waste residues;3. Stabilize remaining wastes to a bearing capacity sufficient to support final cover; and4. Cover the surface impoundment with a final cover designed and constructed to: a. Provide long-term minimization of the migration of liquid through the closed impoundment;b. Function with minimum maintenance;c. Promote drainage and minimize erosion or abrasion of the final cover;d. Accommodate settling and subsidence so that the cover's integrity is maintained; ande. Have a permeability less than or equal to the permeability of any bottom liner system or natural subsoils present.(3) In determining whether or not it is impractical to remove all wastes from an existing impoundment, the Department shall consider the following:(a) The types and volumes of waste in the impoundment;(b) Safety hazards involved in removing hazardous waste from the impoundment; and(c) The extent to which surrounding soil and groundwater have been contaminated.(4) (Effective on and after July 1, 1988) If some waste residues or contaminated materials are left in place at final closure, the owner or operator shall comply with all post-closure requirements set forth in 310 CMR 30.590, including maintenance and monitoring throughout the post-closure period as specified in the license. The owner or operator shall:(a) Maintain the integrity and effectiveness of the final cover, including repairing the cap as necessary to correct the effects of settling, subsidence, erosion, or other events;(b) Maintain and monitor the groundwater monitoring system and comply with all other applicable requirements of 310 CMR 30.660;(c) Prevent run-on or run-off from eroding or otherwise damaging the final cover; and(d) Maintain and monitor the leak detection system in accordance with 310 CMR 30.612(3), and comply with all other requirements set forth in 310 CMR 30.612(3).(5) If an owner or operator of an existing surface impoundment plans to close the impoundment in accordance with 310 CMR 30.617(2)(a), and the impoundment did not meet the double-liner requirements of 310 CMR 30.612(1) at the time the Part A permit application was submitted to the EPA in accordance with 40 CFR Part 270, as in effect July 1, 1983 then: (a) The closure plan for the impoundment pursuant to 310 CMR 30.583 shall include both an expected plan for complying with 310 CMR 30.617(2)(a) and a contingent plan for complying with 310 CMR 30.617(2)(b) in the event that not all contaminated subsoil can be practicably removed at closure; and(b) The owner or operator shall prepare a contingent post-closure plan pursuant to 310 CMR 30.593 for complying with 310 CMR 30.617(4) in case not all contaminated subsoil can be practicably removed at closure.(c) The cost estimates calculated pursuant to 310 CMR 30.903 and 30.905 for closure and post-closure care of an impoundment subject to 310 CMR 30.617(5) shall include the cost of complying with the expected closure plan, the contingent closure plan, and the contingent post-closure plan. Where the costs of the expected closure plan and the contingent closure plan overlap (i.e., the same items are factored into the cost estimate), the costs need not be counted twice.