Illinois (Part 60) Emission Guidelines and (Part 62) State/Federal Plans (Section 111d/129) Delegations

Clean Air Act (CAA) section 111(d), originally enacted in 1970, was intended to cover pollutants that are not regulated under either the criteria pollutant/NAAQS provisions or section 112 of the CAA. It was designed to regulate pollutants from existing sources and new sources that fall in the gap not covered by the criteria pollutant provisions or the hazardous air pollutant provisions. In 1990, Congress added Section 129 to the CAA specifically to address emissions from solid waste combustion.

Sections 111 and 129 require EPA to establish new source performance standards (NSPS) for new units and require the Agency to establish Emission Guidelines for existing units. Both the NSPS and the Emission Guidelines under section 111(d)/129 use a Maximum Achievable Control Technology (MACT) type approach as used under Section 112.

New source performance standards (NSPS) are direct federal regulations that apply to new sources.
Emission guidelines do not directly regulate solid waste combustion units; they establish requirements for state plans, which are the vehicle by which states implement the guidelines.
Once approved, these state plans become federally enforceable.
If a state does not seek approval of a state plan, the federal plan applies.