(a) At closure, the owner or operator must:
  (1) remove or decontaminate all waste residues, contaminated containment system components (liners, etc.) contaminated subsoils, and structures and equipment contaminated with waste and leachate, and manage them as hazardous waste unless 40 Code of Federal Regulations (CFR) §261.3(d) applies; or
  (2) eliminate free liquids by removing liquid wastes or solidifying the remaining wastes and waste residues; stabilize remaining wastes to a bearing capacity sufficient to support final cover; and cover the surface impoundment with a final cover designed and constructed to:
    (A) provide long-term minimization of the migration of liquids 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; and
    (E) have a permeability less than or equal to the permeability of any bottom liner system or natural subsoils present.
(b) If some waste residues or contaminated materials are left in place at final closure, the owner or operator must comply with all post-closure requirements contained in 40 CFR §§264.117 - 264.120, including maintenance and monitoring throughout the post-closure care period (specified in the permit under 40 CFR §264.117). The owner or operator must:
  (1) maintain the integrity and effectiveness of the final cover including making repairs to the cap as necessary to correct the effects of settling, subsidence, erosion, or other events;
  (2) maintain and monitor the leak detection system in accordance with 40 CFR §§264.221(c)(2)(iv) and (3) and 264.226(d), and comply with all other applicable leak detection system requirements of this subchapter;
  (3) maintain and monitor the groundwater monitoring system and comply with all other applicable requirements of §§335.156 - 335.166 of this title (relating to Applicability of Groundwater Monitoring and Response; Required Programs; Groundwater Protection Standard; Hazardous Constituents; Concentration Limits; Point of Compliance; Compliance Period; General Groundwater Monitoring Requirements; Detection Monitoring Program; Compliance Monitoring Program; and Corrective Action Program); and
  (4) prevent run-on and run-off from eroding or otherwise damaging the final cover.
(c) If an owner or operator plans to close a surface impoundment in accordance with subsection (a)(1) of this section, and the impoundment does not comply with the liner requirements of §335.168(a) of this title (relating to Design and Operating Requirements (Surface Impoundments)) and is not exempt from them in accordance with §335.168(b) of this title, then:
  (1) the closure plan for the impoundment under 40 CFR §264.112 must include both a plan for complying with subsection (a)(1) of this section and a contingent plan for complying with subsection (a) (2) of this section, in case not all contaminated subsoils can be practicably removed at closure; and the owner or operator must prepare a contingent post-closure plan under 40 CFR §264.118 for complying with subsection (b) of this section, in case not all contaminated subsoils can be practicably removed at closure;
  (2) the cost estimates calculated under 40 CFR §264.142 and §264.144 for closure and post-closure care of an impoundment subject to this subsection must include the cost of complying with the contingent closure plan and the contingent post-closure plan, but are not required to include the cost of expected closure under subsection (a)(1) of this section.

Source Note: The provisions of this §335.169 adopted to be effective May 28, 1986, 11 TexReg 2347; amended to be effective February 26, 1996, 21 TexReg 1142; amended to be effective November 15, 2001, 26 TexReg 9135