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While stationary engines may be one of the smaller, less significant pieces of equipment at an industrial facility, they are regulated by federal regulations that are complex and difficult to navigate. EPA’s National Emission Standards for Hazardous Air Pollutants (NESHAP) rule for Stationary Reciprocating Internal Combustion Engines (commonly referred to as RICE MACT) has undergone numerous changes since its initial promulgation in 2004, including the most recent amendments finalized on January 13, 2013. The table below provides a high level overview of how the applicability of this rule has been broadened over the course of several years to include almost all stationary RICE.


It is important to note that for certain new or reconstructed RICE, compliance with RICE MACT is achieved by compliance with New Source Performance Standards (NSPS) for stationary internal combustion engines codified in subparts IIII (NSPS for compression ignition [CI] internal combustion engines) and JJJJ (NSPS for spark ignition [SI] internal combustion engines).

The latest round of amendments to the rule address issues raised by various stakeholders and include the following key changes:

  • The addition of an alternative compliance demonstration method for existing and new stationary 4-stroke rich burn non-emergency engines > 500 HP located at major sources of HAPs and for existing 4SRB non-emergency engines >500 hp located at area sources of HAPs
  • The allowance for owners/operators of stationary emergency RICE to operate their engines as part of an emergency demand response program for up to 100 hours per year (including hours spent for maintenance and testing)
  • A provision for existing emergency engines located at area sources to participate in peak shaving (non-emergency demand response) for up to 50 hours per year prior to May 3, 2014
  • The creation of a subcategory for existing spark ignition engines located in sparsely populated areas.
  • Additional miscellaneous clarifications, corrections and provisions

In consideration of the 2013 compliance deadlines for subject stationary RICE, it is critical for owners and operators to assess specific applicability and compliance obligations closely while bearing the following in mind:

  • HAP Status: Is your site a major source or an area source of HAPs?
  • Facility Location: Is your engine located in a sparsely populated area remote from human activity? Is your engine located in Alaska? Is your engine located in a state or local district that will require the installation of controls/upgrades to meet more stringent local standards?
  • Stationary determination: Is your RICE stationary or does it qualify as a non-road/mobile/portable engine?
  • Engine dates: Is your stationary RICE “new”, “existing”, or “reconstructed”? When was the stationary RICE installed, built, purchased, reconstructed or modified?
  • Purpose of RICE: Is your stationary RICE meant to serve emergency or non-emergency use? If you consider your stationary RICE to be for emergency use only, does it meet the regulatory definition for such use?
  • Fuel type: Is your stationary RICE fueled by diesel, natural gas, gasoline, propane, or landfill gas?
  • Engine type: What is your stationary RICE’s horsepower rating? Is it a 2 stroke (2S), 4 stroke (4S), lean burn (LB) or rich burn (RB) stationary RICE?

The RICE MACT is among the most complex and confusing regulations in EPA’s entire suite of NSPS and NESHAP regulations and includes a slew of requirements related to testing, notifications, reporting, and recordkeeping. Trinity has tools available to assist in your RICE MACT applicability determinations. To determine whether the RICE MACT has been evaluated accurately at your facility and address its future compliance, contact your local Trinity office at (800) 229-6655.

1A major source of HAPs is defined as a site that has the potential to emit ≥ 10 tpy single HAP or ≥ 25 tpy any combination of HAPs.
2 An area source of HAPs is defined as a site that is not a major source of HAPs.
3 Existing sources covered by 2010 amendments are stationary RICE constructed orreconstructed on or after June 12, 2006.