60. The concentration of methane in biogas produced by the residual materials disposed of in an engineered landfill must not exceed 25% of its lower explosive limit, or 1.25% by volume, if it is emitted or migrates into and accumulates in the soil and the buildings or facilities (other than the leachate, water and biogas collection or treatment systems) situated at a maximum distance of 150 m from the disposal areas without exceeding the outside perimeter of any buffer zone established under section 18.
For the purposes of this section, “lower explosive limit” means the lowest concentration, by volume, of a gas in a gas mixture above which a flare may sustain itself at a temperature of 25°C and a pressure of 101.325 kPa.