(1) The owner or operator of a Class II landfill unit shall ensure that:
(a) the concentration of methane gas generated by the facility does not exceed 25 percent of the lower explosive limit for methane in facility structures, excluding gas control or recovery system components; and
(b) the concentration of methane gas does not exceed the lower explosive limit for methane at the facility property boundary.
(2) The owner or operator of a Class II landfill unit shall implement a routine methane monitoring program to ensure that the standards of (1) are met.
(3) The minimum frequency of monitoring required in (2) is quarterly, except as provided in (7). The type and frequency of monitoring required in (2) must be determined based on the following factors:
(a) soil conditions;
(b) the hydrogeologic conditions surrounding the facility;
(c) the hydraulic conditions surrounding the facility;
(d) the location of facility structures and property boundaries.
(4) If methane gas levels exceeding the limits specified in (1) are detected, the owner or operator shall:
(a) immediately take all necessary steps to ensure protection of human health and notify the department;
(b) within seven days after detection, place in the operating record specification of the methane gas levels detected and a description of the steps taken to protect human health; and
(c) within 60 days after detection, submit for department approval, and implement, a remediation plan for controlling methane gas releases, place a copy of the plan in the operating record, and notify the department that the plan has been implemented.
(5) The remediation plan in (4)(c) must:
(a) describe the nature and extent of the problem and the proposed remedy;
(b) provide design plans for the proposed remedy; and
(c) for construction of all methane gas control systems required in this rule, contain a submission for department approval that includes plans, specifications, reports, and certifications to the same extent as required in ARM 17.50.1205.
(6) The department may establish alternative schedules for demonstrating compliance with (4)(b) and (c).
(7) The department may establish alternative frequencies for the monitoring requirement of (3), after public review and comment, for an owner or operator of a Class II landfill unit that disposes of 20 tons or less of municipal solid waste per day, based on an annual average. Any alternative monitoring frequencies established under this paragraph must:
(a) be based on the unique characteristics of small communities;
(b) take into account climatic and hydrogeologic conditions; and
(c) be protective of human health and the environment.