EPA Proposes Revisions to Reciprocating Internal Combustion Engine (RICE) MACT

On March 5, 2009, EPA published proposed revisions to 40 CFR 63 Subpart ZZZZ - National Emission Standards for Reciprocating Internal Combustion Engines (RICE MACT). In the revisions, EPA proposed to set emission limits for formaldehyde, benzene, acrolein and other toxic air pollutants from certain stationary diesel and gas-fired engines at both major and area sources for hazardous air pollutants (HAPs). An area source is a facility which emits less than 10 tons per year of a single HAP or 25 tons per year of combined HAPs. The promulgation of these regulations means that many previously unregulated smaller engines, including those designated for emergency use, may soon be subject to federal emission standards, management practices, testing, and monitoring requirements.

For major (non-area) sources of air toxics, the proposed revisions to this rule apply to engines that are: (1) smaller than or equal to 500 horsepower that were constructed or reconstructed before June 12, 2006, or (2) larger than or equal to 500 horsepower that were constructed or reconstructed before December 19, 2002. The proposed limits apply to all existing spark ignition (SI) and compression ignition (CI) RICE located at area sources. The EPA also proposed limits that apply to all engines (existing and new) during periods of startup, shutdown, and malfunction.

For the categories of engines included above, owners and operators would be required to meet emission limits for engines located at major sources, as well as emission limits or management practices (depending on the size and use of the engine) for engines located area sources. For larger non-emergency engines, EPA expects that sources will have to install "aftertreatment" controls to engine exhaust systems to meet the emission limits. Suggested control technologies include non-selective catalytic reduction, oxidation catalysts, and catalyzed diesel particulate filters.

Additionally, owners and operators would be required to perform emissions tests for non-emergency engines greater than 100 hp at major sources and engines subject to a numerical standard at area sources. Non-emergency engines > 500 hp at both area sources and major sources would require continuous parametric monitoring (e.g., monitor the temperature of the exhaust at the catalyst inlet).

Click for a copy of the proposed revisions. Comments on the proposed rule are due May 4, 2009.

For questions regarding the proposed revisions to the RICE MACT, contact Jack Mitchell at jmitchel@trinityconsultants.com or (253) 867-5600.