NR 664.0301(1)(b)1.b.b. Of sufficient strength and thickness to prevent collapse under the pressures exerted by overlying wastes, waste cover materials and any equipment used at the landfill.

NR 664.0301(2)(2) The owner or operator will be exempted from the requirements of sub. (1) if the department 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 s. NR 664.0093) into the groundwater or surface water at any future time. In deciding whether to grant an exemption, the department will consider all of the following:

NR 664.0301(2)(a)(a) The nature and quantity of the wastes.

NR 664.0301(2)(b)(b) The proposed alternate design and operation.

NR 664.0301(2)(c)(c) 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.

NR 664.0301(2)(d)(d) 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.

NR 664.0301(3)(3) The owner or operator of each new landfill unit on which construction commences after June 1, 1995, each lateral expansion of a landfill unit on which construction commences after June 1, 1995, and each replacement of an existing landfill unit that is to commence reuse after June 1, 1995 shall install 2 or more liners and a leachate collection and removal system above and between the liners. “Construction commences” is as defined in s. NR 660.10 under “existing facility”.

NR 664.0301(3)(a)(a)

NR 664.0301(3)(a)1.a.a. A top liner designed and constructed of materials (e.g., a geomembrane) to prevent the migration of hazardous constituents into the liner during the active life and long-term care period.

NR 664.0301(3)(a)1.b.b. A composite bottom liner, consisting of at least 2 components. The upper component shall be designed and constructed of materials (e.g., a geomembrane) to prevent the migration of hazardous constituents into this component during the active life and long-term care period. The lower component shall be designed and constructed of materials to minimize the migration of hazardous constituents if a breach in the upper component were to occur. The lower component shall be constructed of at least 3 feet (91 cm) of compacted soil material with a hydraulic conductivity of no more than 1×10-7 cm/sec.

NR 664.0301(3)(b)(b) The leachate collection and removal system immediately above the top liner shall be designed, constructed, operated and maintained to collect and remove leachate from the landfill during the active life and long-term care period. The department will specify design and operating conditions in the operating license to ensure that the leachate depth over the liner does not exceed 30 cm (one foot). The leachate collection and removal system shall comply with par. (c) 3. and 4.

NR 664.0301(3)(c)(c) The leachate collection and removal system between the liners, and immediately above the bottom composite liner in the case of multiple leachate collection and removal systems, is also a leak detection system. This leak detection system shall be capable of detecting, collecting and removing leaks of hazardous constituents at the earliest practicable time through all areas of the top liner likely to be exposed to waste or leachate during the active life and long-term care period. The requirements for a leak detection system in this subsection are satisfied by installation of a system that is, at a minimum, all of the following:

NR 664.0301(3)(c)2.2. Constructed of granular drainage materials with a hydraulic conductivity of 1×10-2 cm/sec or more and a thickness of 12 inches (30.5 cm) or more; or constructed of synthetic or geonet drainage materials with a transmissivity of 3×10-5 m2/sec or more.

NR 664.0301(3)(c)3.3. Constructed of materials that are chemically resistant to the waste managed in the landfill and the leachate expected to be generated, and of sufficient strength and thickness to prevent collapse under the pressures exerted by overlying wastes, waste cover materials and equipment used at the landfill.

NR 664.0301(3)(c)5.5. Constructed with sumps and liquid removal methods (e.g., pumps) of sufficient size to collect and remove liquids from the sump and prevent liquids from backing up into the drainage layer. Each unit shall have its own sump. The design of each sump and removal system shall provide a method for measuring and recording the volume of liquids present in the sump and of liquids removed.

NR 664.0301(3)(d)(d) The owner or operator shall collect and remove pumpable liquids in the leak detection system sumps to minimize the head on the bottom liner.

NR 664.0301(3)(e)(e) The owner or operator of a leak detection system that is not located completely above the seasonal high water table shall demonstrate that the operation of the leak detection system will not be adversely affected by the presence of groundwater.

NR 664.0301(4)(4) The department may approve alternative design or operating practices to those specified in sub. (3) if the owner or operator demonstrates to the department that the design and operating practices, together with location characteristics, will do both of the following:

NR 664.0301(4)(a)(a) 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 sub. (3).

NR 664.0301(4)(b)(b) Allow detection of leaks of hazardous constituents through the top liner at least as effectively.

NR 664.0301(5)(5) The double liner requirement in sub. (3) may be waived by the department for any monofill, if pars. (a) and (b) 1. or 2. apply:

NR 664.0301(5)(a)(a) The monofill contains only hazardous wastes from foundry furnace emission controls or metal casting molding sand, and the wastes do not contain constituents which would render the wastes hazardous for reasons other than the toxicity characteristic in s. NR 661.0024, with EPA hazardous waste numbers D004 to D017.