Methane emissions constitute 9 percent of all anthropogenic greenhouse gas (GHG) emissions in the United States, and the third largest source of those emissions are municipal solid waste (MSW) landfills. Accordingly, President Obama has made controlling methane emissions a significant part of his Climate Action Plan.  The EPA has now come forward with two actions addressing methane at new and existing MSWs.

New sources

First, the Agency is proposing amendments to its New Source Performance Standards (NSPS) for MSW landfills, which would affect facilities constructed, modified, or reconstructed after publication of the proposal in the Federal Register.  The CAA requires that the EPA review and, if necessary, revise NSPSs every 8 years.  The MSW NSPS were issued in 1996 and have not been updated since.  In addition, the EPA is subject to a legal settlement requiring action on the MSW NSPS.

Under the current NSPS, or baseline, an MSW landfill that has a design capacity of 2.5 million megagrams (Mg) and 2.5 million m3 must install and start up a gas collection control system (GCCS) within 30 months after landfill gas (LFG) emissions reach or exceed a level of 50 Mg of nonmethane organic compounds (NMOC) per year. (A megagram, or metric ton, is equal to 1.1 U.S. short tons or about 2,205 pounds.)

NMOCs are used in the NSPS as a surrogate for LFG, which includes methane.  The proposal would retain the same design capacity threshold as the baseline, but reduce the NMOC emissions threshold to 40 Mg/yr.  The GCCS may be a nonenclosed flare, an enclosed combustion device, or a treatment system that processes the collected gas for subsequent sale or beneficial use.

The proposal includes requirements to monitor for methane emissions along the collection area and operate the GCCS so that the methane concentration is less than 500 parts per million above background at the surface of the landfill.

In addition, the proposal would clarify that the use of treated LFG is not limited to use as a fuel for a stationary combustion device and may also serve other beneficial uses, such as vehicle fuel, production of high-Btu gas for pipeline injection, and use as a raw material in a chemical manufacturing process.  The EPA is also proposing to clarify what constitutes LFG treatment.

Existing sources

Second, the EPA has issued an advanced notice of proposed rulemaking (ANPRM) requesting public input on revising the 1996 guidelines to reduce emissions from nearly 1,000 existing MSW landfills subject to those guidelines.  The Agency says that several parameters could be adjusted to potentially achieve additional emissions reductions. Those parameters include design capacity, the NMOC emissions threshold, and the timing of installing and expanding the GCCS.

Approaches also include consideration of best management practices and new technologies that could improve collection and control of LFG emissions.

The EPA says it will consider input and data received on these approaches during the review of the MSW emissions guidelines and determine whether it is appropriate to revise those guidelines to further reduce LFG emissions from existing landfills.

The proposal and ANPRM