EPA Finalizes AP-42 Chapter 2, Section 4 – MSW Landfills

August 28, 2024

Recent EPA AP-42, Compilation of Air Pollutant Emissions Factors from Stationary Sources Update Regarding Municipal Solid Waste Landfills

A revision to AP-42 regarding Municipal Solid Waste (MSW) Landfills was finalized on August 15, 2024. AP-42 is the Compilation of Air Pollutant Emission Factors guidance developed by the U.S. Environmental Protection Agency (EPA) to evaluate air pollution emissions from various sources. EPA drafted new emission factors for the MSW Landfill portion of AP-42 on January 12, 2024 and offered a 60-day public comment period that ended March 12, 2024.

Highlights of this final action include:

• Removal of the first order kinetic equation to calculate methane generation rate and replaced with the Mandatory Greenhouse Gas Reporting equation HH-1 found in 40 CFR 98.343(a)(1).
  • The New Source Performance Standards (NSPS) and National Emissions Standards for Hazardous Air Pollutants (NESHAP) still reference the use of k and lo values found in AP-42, even though those references have been taken out of AP-42 alongside the first order equation.

   

• Default concentrations of NMOC have been finalized for co-disposal sites prior to 1992 of 2400 ppmv and for non-co-disposal sites of 600 ppmv for pre 1992 site and 550 ppmv for after 1992 sites.
  • Additionally, EPA concluded that Non-Methane Organic Compound (NMOC) emissions are a good surrogate for Volatile Organic Compound (VOC) emissions, and removed the reference to a 39% ratio of VOC to NMOC.

   

• EPA combined emission factors for secondary compounds exiting open flares and enclosed combustors and provided additional NMOC emission factors for engines at various loads while lowering emission factors for nitrous oxide and carbon monoxide.

For additional information, please contact SCS Engineers, or visit the EPA Air Emissions Factors and Quantification website.