Maine DEP Amends Its Air Licensing Regulations


[authors: Dixon P. Pike and Brian M. Rayback]

Recently, the Maine DEP adopted amendments to its air licensing regulations, including Chapter 100, Definitions; Chapter 115, Major and Minor Source Air Emission License Regulations; and Chapter 140, Part 70 Air Emission License Regulations.  The amendments became effective December 1, 2012

The primary purpose of the amendments is to implement the federal New Source Review (NSR) program for fine particulate matter (a.k.a. PM2.5).  However, the amendments included a number of other important changes that should be considered by facilities filing applications for minor or major NSR licenses under Chapter 115 or applications for renewal or amendment of Chapter 140/Title V air licenses. 

Some of the more significant amendments include: 

  • Clarification that baseline for netting purposes is any 24-month period in the last 10 years, instead of the 2 years prior to the application;
  • At least until July 21, 2014, exclude from the definition of regulated “greenhouse gases” CO2 emissions resulting from the combustion or decomposition of non-fossilized and biodegradable organic material;
  • Clarification that, for existing sources, netting can be based on the past-actual-to- projected-actual emission approach;
  • Addition of plantwide applicability limit (PAL) provisions;
  • Revision to the definition of “PM10” and “PM2.5” to include condensable particulate matter (a.k.a. “the back-half catch”);
  • Clarification that the emissions from all emissions units (including insignificant activities) must be included when performing netting calculations; and
  • For Chapter 140 sources, reduction of the insignificant activity category for stationary internal combustion engines from 3.0 MMBtu/hr to 1.7 MMBtu/hr.

If you have any questions about how these amendments may affect compliance with existing air licenses, applications for minor or major NSR licenses under Chapter 115 or pending/upcoming applications for renewal of Part 70/Title V licenses under Chapter 140, please do not hesitate to contact Dixon Pike (207-791-1374 or or Brian Rayback (207-791-1188 or

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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