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  Background Information Document for Updating AP42 Section 2.4 for Estimating Emissions from Municipal Solid Waste Landfills (EPA/600/R-08/116) September 2008

Background Information Document for Updating AP42 Section 2.4 for Estimating Emissions from Municipal Solid Waste Landfills

This document was prepared for U.S. EPA's Office of Research and Development in support of EPA's Office of Air Quality Planning and Standards (OAQPS). The objective is to summarize available data used to update emissions factors for quantifying landfill gas emissions and combustion by-products using more up-to-date and representative data for U.S. municipal landfills. This document provides background information used in developing a draft of the AP-42 section 2.4 which provides guidance for developing estimates of landfill gas emissions for national, regional, and state emission inventories. EPA OAQPS will be conducting the review of Section 2.4. Once comments are addressed, the AP-42 section will be updated and available through EPA's Technology Transfer Network (TTN) Clearinghouse for Inventories & Emissions (http://www.epa.gov/ttn/chief/ap42/). This report is considered a stand-alone report providing details of available data and analysis for developing landfill gas emission factors and combustion by-products for a wider range of pollutants and technologies.

The inputs that are described in this report are used in EPA's Landfill Gas Emission Model (LandGEM) for developing inputs for state, regional, and national emission inventories. Data from 62 LFG emissions tests from landfills with waste in place on or after 1992 were used to develop updated factors for use in LandGEM. This document also provides updated and additional emission factors for combustion by-products for control devices such as flares, boilers, and engines.

Of the 293 emissions tests submitted to EPA for this update, over 200 contained inadequate documentation or information for use in this update. The reports that were used included LFG composition data and, in some cases, emissions data on LFG combustion by-products. These emissions tests were screened for quality and compiled to create emission factors for non-methane organic compounds (NMOC), as well as speciated compounds in LFG. This update expands the list of emission factors for LFG constituents from 44 to 167 and provides many more "A" quality rated emission factors. Likewise, combustion by-product emission factors for dioxins/furans were added in this update, along with improved ratings of the other combustion by-product emission factors as a result of the addition of new data.

Updated information is provided of changes in the design and operation of U.S. MSW landfills along with updated statistics on the amount of waste being landfilled. Information on quantifying area source emissions (OTM10) is provided based on the use of Optical Remote Sensing technology and Radial Plume Mapping (ORS-RPM). The first-order equation used to estimate LFG emissions has been modified to add a factor to account for LFG capture efficiency. Due to the increase in the use of leachate recirculation, a gas production rate to characterize emissions from wet landfills has been added. The rate constant is based on an optimum moisture content using data from about 30 landfills using leachate recirculation. Information on air emission concerns regarding construction/demolition waste landfills and landfill fires have also been added to the AP-42 section.


Susan Thorneloe

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