Sec. 26.13.05.14. Landfills

A. Applicability. This regulation applies to owners and operators of facilities that dispose of hazardous waste in landfills, except as Regulation .01 of this chapter provides otherwise.

B. Design and Operating Requirements.

(1) Any landfill not covered by §B(3) of this regulation or COMAR 26.13.06.22C shall have a liner system for all portions of the landfill, except for existing portions of the landfill. The liner system shall:

(a) Have a liner that is designed, constructed, and installed to prevent any migration of wastes out of the landfill to the adjacent subsurface soil or ground water or surface water at any time during the active life, including the closure period, of the landfill. The liner shall be constructed of materials that prevent wastes from passing into the liner during the active life of the facility. The liner shall be:

(i) Constructed of materials that have appropriate chemical properties and sufficient strength and thickness to prevent failure due to pressure gradients, including static head 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;

(ii) 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;

(iii) Installed to cover all surrounding earth likely to be in contact with the waste or leachate; and

(iv) Located entirely above natural seasonal high water table. Minimal distance will be specified by the Secretary in the permit.

(b) Have a leachate collection and removal system immediately above the liner that is designed, constructed, maintained, and operated to collect and remove leachate from the landfill. The Secretary will specify design and operating conditions in the permit to ensure that the leachate depth over the liner does not exceed 30 cm (1 foot). The leachate collection and removal system shall be:

(i) 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 by any equipment used at the landfill; and

(ii) Designed and operated to function without clogging through the scheduled closure of the landfill.

(c) Be located in a geohydrologic setting which is compatible with hazardous waste land disposal as determined by the Secretary. Compatibility criteria shall include but not be limited to the:

(i) Attenuative capacity of the in-situ soils;

(ii) Hydraulic conductivity of the in-situ soils;

(iii) Thickness and classification of in-situ soils; and

(iv) Water table surface or potentiometric surface of each aquifer within 50 feet of the facility boundaries.

(2) The owner or operator will be exempted from the requirements of §B(1) of this regulation if the Secretary 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 Regulation .06-1B of this chapter) into the ground water or surface water at any future time. In deciding whether to grant an exemption, the Secretary shall consider:

(a) The nature and quantity of the wastes;

(b) The proposed alternate design and operation;

(c) The hydrogeologic setting of the facility, including the attenuative capacity and thickness of the liners and soils present between the landfill and ground water or surface waters; and

(d) All other factors which would influence the quality and mobility of the leachate produced and the potential for it to migrate to ground water or surface water.

(3) The owner or operator of each new landfill, each new landfill unit at an existing facility, each replacement of an existing landfill unit, and each lateral expansion of an existing landfill unit, shall install two or more liners and a leachate collection system above and between the liners. The liners and leachate collection systems shall protect human health and the environment. The requirement for the installation of two or more liners in this subsection may be satisfied by the installation of a top liner designed, operated, and constructed of materials to prevent the migration of any constituent into the liner during the period the facility remains in operation, including any post-closure monitoring period, and a lower liner designed, operated, and constructed to prevent the migration of any constituent through the liner during this period. For the purposes of the preceding sentence, a lower liner shall be considered to satisfy this requirement if it is constructed of at least a 3-foot thick layer of recompacted clay or other natural material with a hydraulic conductivity of no more than 1 × 10^-7) centimeter per second.

(4) Section B(3) will not apply if the owner or operator demonstrates to the Secretary and the Secretary finds for the landfill, that alternative design and operating practices, together with location characteristics, will prevent the migration of any hazardous constituent into the ground water or surface water at least as effectively as the liners and leachate collection systems.

(5) The double liner requirement set forth in §B(3) of this regulation may be waived by the Secretary for any monofill, if:

(a) The monofill contains only hazardous wastes from foundry furnace emission controls or metal casting molding sand, and these wastes do not contain constituents which would render the wastes hazardous for reasons other than exhibiting the toxicity characteristic in COMAR 26.13.02.14 for one or more of EPA hazardous waste numbers D004-D017; and

(b) One of the following applies:

(i) The monofill has at least one liner for which there is no evidence that the liner is leaking, the monofill is located more than 1/4 mile from an underground source of drinking water, as defined in 40 CFR §144.3, and the monofill is in compliance with generally applicable ground water monitoring requirements for facilities with permits under COMAR 26.13.07; or

(ii) 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 ground water or surface water at any future time.

(6) The owner or operator shall 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 25-year storm.

(7) The owner or operator shall design, construct, operate, and maintain a run-off management system to collect and control at least the water volume resulting from a 24-hour, 25-year storm.

(8) Collection and holding facilities (for example, tanks or basins) associated with run-on and run-off control systems shall be emptied or otherwise managed expeditiously after storms to maintain design capacity of the system.

(9) If the landfill contains any particulate matter which may be subject to wind dispersal, the owner or operator shall cover or otherwise manage the landfill to control wind dispersal.

(10) The Secretary will specify in the permit all design and operating practices that are necessary to ensure that the requirements of this section are satisfied.

C. Monitoring and Inspection.

(1) During construction or installation, liners, except in the case of existing portions of liners exempt from §B, of this regulation, and cover systems (for example, membranes, sheets, or coatings) shall be inspected for uniformity, damage, and imperfections (for example, holes, cracks, thin spots, or foreign materials). Immediately after construction or installation:

(a) Synthetic liners and covers shall be inspected to ensure tight seams and joints and the absence of tears, punctures, or blisters; and

(b) Soil-based and admixed liners and covers shall be inspected for imperfections including lenses, cracks, channels, root holes, or other structural non-uniformities that may cause an increase in the permeability of the liner or cover.

(2) While a landfill is in operation, it shall be inspected weekly and after storms to detect evidence of any of the following:

(a) Deterioration, malfunctions, or improper operation of run-on and run-off control systems;

(b) The presence of liquids in leak detection systems;

(c) Proper functioning of wind dispersal control system, when present; and

(d) The presence of leachate in and proper functioning of leachate collection and removal systems, when present.

D.-H. (Reserved)

I. Surveying and Record keeping. The owner or operator of a landfill shall maintain the following items in the operating record required under Regulation .05D:

(1) On a map, the exact location and dimensions, including depth of each cell with respect to permanently surveyed benchmarks; and

(2) The contents of each cell and the approximate location of each hazardous waste type within each cell.

J. Closure and Post-Closure Care.

(1) At final closure of the landfill or upon closure of any cell the owner or operator shall cover the landfill or cell with a final cover designed and constructed to:

(a) Provide long-term minimization of migration of liquids through the closed landfill;

(b) Function with minimum maintenance;

(c) Promote drainage and minimize erosion or abrasion of the 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.

(2) After final closure, the owner or operator shall comply with all post-closure requirements, contained in Regulation .07G-J of this chapter, including maintenance and monitoring throughout the post-closure care period. The owner or operator shall:

(a) 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;

(b) Continue to operate the leachate collection and removal system:

(i) During post-closure period; or

(ii) Until leachate is no longer detected;

(c) Maintain and monitor the ground water monitoring system and comply with all other applicable requirements of Regulations .06-.06-7 of this chapter;

(d) Prevent run-on and run-off from eroding or otherwise damaging the final cover; and

(e) Protect and maintain surveyed benchmarks used in complying with §I of this regulation.

K. Reserved.

L. Special Requirements for Ignitable or Reactive Waste. Except as provided in §L(2) of this regulation, ignitable or reactive waste may not be placed in a landfill, unless the waste is treated, rendered, or mixed before or immediately after placement in a landfill so that:

(1) The resulting waste, mixture, or dissolution of material no longer meets the definition of ignitable or reactive waste under COMAR 26.13.02.11 or .13; and

(2) Regulation .02H(2) of this chapter is complied with.

M. Special Requirements for Incompatible Wastes. Incompatible wastes, or incompatible wastes and materials (see Regulation .24 of this chapter for example), may not be placed in the same landfill cell, unless Regulation .02H(2) of this chapter is complied with.

N. Special Requirements for Liquid Waste.

(1) A person may not place waste which contains free liquids in a landfill, including bulk waste, non-containerized waste, or waste in containers.

(2) To demonstrate the absence or presence of free liquids, a person shall use Method 9095, Paint Filter Liquids Test, as described in "Test Methods for Evaluating Solid Waste, Physical/Chemical Methods", EPA Publication SW-846, which is incorporated by reference in COMAR 26.13.01.05A(4).

O. Special Requirements for Containers. Unless the containers are very small, such as ampules, an owner or operator shall ensure that containers are:

(1) At least 90 percent full when placed in a landfill; or

(2) Crushed, shredded, or similarly reduced in volume to the maximum extent practicable before burial in a landfill.

P. Special Requirements for Hazardous Wastes F020, F021, F022, F023, F026, and F027.

(1) Hazardous Wastes F020, F021, F022, F023, F026, and F027 may not be placed in a landfill unless the owner or operator operates the landfill in accord with a management plan for these wastes that is approved by the Secretary under the standards set out in this section, and in accord with all other applicable requirements of this chapter. The factors to be considered are:

(a) The volume, physical, and chemical characteristics of the wastes including their potential to migrate through the soil or to volatilize or escape into the atmosphere;

(b) The attenuative properties of underlying and surrounding soils or other materials;

(c) The mobilizing properties of other materials co-disposed with these wastes; and

(d) The effectiveness of additional treatment, design, or monitoring requirements.

(2) The Secretary may determine that additional design, operating, and monitoring requirements are necessary for landfills managing hazardous wastes F020, F021, F022, F023, F026, and F027 in order to reduce the possibility of migration of these wastes to ground water, surface water, or air so as to protect human health and the environment.