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EPA Proposes Amendments to Standards for Stationary Tier 4 Compression Ignition Engines

Posted Tuesday, December 1st, 2015

On November 6, 2015, the U.S. Environmental Protection Agency (EPA) proposed amendments to the new source performance standards (NSPS) for stationary compression ignition (CI) internal combustion engines in Tier 4. Under the proposed amendments, manufactures of stationary CI could design engines to allow operators to temporarily override certain performance-related NOx controls when needed to respond to emergency situations. Qualifying emergency situations include those in which normal operation of the emission controls poses a significant direct or indirect risk to human life. EPA previously adopted such a rule for manufacturers designing certified “nonroad” CI engines. The proposed amendments are intended to provide engine operators short-term relief without the need to contact the engine manufacturer or EPA.

During qualifying emergencies, engine operators would still be required to meet the less stringent Tier 1 emission standards with auxiliary emission control devices (AECDs). The override could be activated for up to 120 engine hours before requiring reactivation. Operators would report use of the AECD within 60 days to the manufacturer, and manufacturers would annually report on such use to EPA. EPA would retain authority to evaluate whether use of the AECD was reasonable based on the risk to human life and whether normal emissions controls were curtailing engine performance. Comments are due on EPA’s proposal by December 21, 2015.

For additional information contact Jon Harris Maurer.

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