(a) Any landfill that is not covered by subsection (c) of this section or 40 Code of Federal Regulations (CFR) §265.301(a) must have a liner system for all portions of the landfill (except for existing portions of such landfill). The liner system must have:
  (1) a liner that is designed, constructed, and installed to prevent any migration of wastes out of the landfill to the adjacent subsurface soil or groundwater or surface water at any time during the active life (including the closure period) of the landfill. The liner must be constructed of materials that prevent wastes from passing into the liner during the active life of the facility. The liner must be:
    (A) constructed of materials that have appropriate chemical properties and sufficient strength and thickness to prevent failure due to pressure gradients (including static head and external hydrogeologic forces), physical contact with the waste or leachate to which they are exposed, climatic conditions, the stress of installation, and the stress of daily operation;
    (B) placed upon a foundation or base capable of providing support to the liner and resistance to pressure gradients above and below the liner to prevent failure of the liner due to settlement, compression, or uplift; and
    (C) installed to cover all surrounding earth likely to be in contact with the waste or leachate; and
  (2) a liner that:
    (A) prevents any migration of wastes out of the landfill to the adjacent subsurface soil or groundwater or surface water at any time prior to the end of the post-closure care period; and
    (B) minimizes the rate of migration of wastes out of the landfill to the adjacent subsurface soil or groundwater or surface water so as not to pose a substantial present or potential hazard to human health and the environment; and
  (3) a leachate collection and removal system immediately above the top liner that is designed, constructed, maintained, and operated to collect and remove leachate from the landfill. The commission will specify design and operating conditions in the permit to ensure that the leachate depth over the liner does not exceed 30 centimeters (one foot). The leachate collection and removal system must be:
    (A) constructed of materials that are:
      (i) chemically resistant to the waste managed in the landfill and the leachate expected to be generated; and
      (ii) of sufficient strength and thickness to prevent collapse under the pressures exerted by overlying wastes, waste cover materials, and by any equipment used at the landfill; and
    (B) designed and operated to function without clogging through the scheduled closure of the landfill.
(b) The owner or operator will be exempted from the requirements of subsection (a) of this section if the commission finds, based on a demonstration by the owner or operator, that alternative design and operating practices, together with location characteristics, will prevent the migration of any hazardous constituents (see §335.159 of this title (relating to Hazardous Constituents)) into the groundwater or surface water at any future time. In deciding whether to grant an exemption, the commission will consider:
  (1) the nature and quantity of the wastes;
  (2) the adopted alternate design and operation;
  (3) the hydrogeologic setting of the facility, including the attenuative capacity and thickness of the liners and soils present between the landfill and groundwater or surface water; and
  (4) all other factors which would influence the quality and mobility of the leachate produced and the potential for it to migrate to groundwater or surface water.
(c) The owner or operator of each new landfill unit on which construction commences after January 29, 1992, each lateral expansion of a landfill unit on which construction commences after July 29, 1992, and each replacement of an existing landfill unit that is to commence reuse after July 29, 1992, must comply with 40 CFR §264.301(c) as amended through January 29, 1992, at 57 FedReg 3489.
(d) The executive director may approve alternative design or operating practices to those specified in subsection (c) of this section if the owner or operator demonstrates to the executive director that such design and operating practices, together with location characteristics:
  (1) will prevent the migration of any hazardous constituent into the groundwater or surface water at least as effectively as the liners and leachate collection and removal systems specified in subsection (c) of this section; and
  (2) will allow detection of leaks of hazardous constituents through the top liner at least as effectively.
(e) The double liner requirement set forth in subsection (c) of this section may be waived by the commission for any monofill which contains only hazardous wastes from foundry furnace emission controls or metal casting molding sand, and such wastes do not contain constituents which would render the wastes hazardous for reasons other than the toxicity characteristics in 40 CFR §261.24, and is in compliance with either paragraph (1) or (2) of this subsection.
  (1) The monofill:
    (A) has at least one liner for which there is no evidence that such liner is leaking;
    (B) is located more than 1/4 mile from an "underground source of drinking water" (as that term is defined in §331.2 of this title (relating to Definitions)); and
    (C) is in compliance with groundwater monitoring requirements of this subchapter.
  (2) The owner or operator demonstrates that the monofill is located, designed, and operated so as to assure that there will be no migration of any hazardous constituent into groundwater or surface water at any future time.
(f) The owner or operator of any replacement landfill unit is exempt from subsection (c) of this section if:
  (1) The existing unit was constructed in compliance with the design standards of §3004(o)(1)(A)(i) and (o)(5) of the Resource Conservation and Recovery Act; and
  (2) There is no reason to believe that the liner is not functioning as designed.
(g) The owner or operator must design, construct, operate, and maintain a run-on control system capable of preventing flow onto the active portion of the landfill during peak discharge from at least a 100-year storm.
(h) The owner or operator must design, construct, operate, and maintain a run-off management system to collect and control at least the water volume from active portions resulting from a 24-hour, 100-year storm.
(i) Collection and holding facilities (e.g., tanks or basins) associated with run-on and run-off control systems must be emptied or otherwise managed expeditiously after storms to maintain design capacity of the system.
(j) If the landfill contains any particulate matter which may be subject to wind dispersal, the owner or operator must cover or otherwise manage the landfill to control wind dispersal.
(k) The commission will specify in the permit all design and operating practices that are necessary to ensure that the requirements of this section are satisfied.

Source Note: The provisions of this §335.173 adopted to be effective May 28, 1986, 11 TexReg 2347; amended to be effective March 18, 1991, 16 TexReg 1369; amended to be effective November 23, 1993, 18 TexReg 8218; amended to be effective February 26, 1996, 21 TexReg 1142; amended to be effective October 29, 2009, 34 TexReg 7321