The minimum frequency of monitoring shall be quarterly. The decomposition of municipal solid waste produces explosive gases, including methane, carbon dioxide, and hydrogen sulfide. Methane is the constituent of most concern, as it is colorless, odorless, and highly combustible. Sampling air within facility structures where gas can accumulate and sampling soil at the property boundary is necessary to prevent methane buildup.
Early warning allows the owner or operator to take action to prevent catastrophic events.
Early detection allows owners and operators to take appropriate remedial measures to prevent or minimize environmental damage from migrating gases. EPA has established a quarterly gas monitoring frequency as a minimum. Federal Register 33314. 56 Federal Register 50978. U.S. EPA. 1993.