38 M.R.S. § 591-A

1. Modifications. Modification of a licensed source means any physical or operational change in an emission unit or emission source that: A. Increases the quantity of any air contaminant emitted; [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] B. Increases the impact of the emissions of that emission unit or source on ambient air quality due to changes in stack height, physical building characteristics or plume characteristics unless the commissioner finds that the change will not cause a violation of ambient air quality standards and ambient increment standards; [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] C. Results in the emission of any air contaminant not previously emitted; [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] D. Constitutes construction of a new emission unit; or [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] E. Constitutes the reconstruction of a new emission unit as defined in 40 Code of Federal Regulations, 60.15 (1990). [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).]

2. Changes not considered modifications. The following changes are not modifications to a licensed source: A. Routine maintenance, repair and replacement; [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] B. An increase in the production rate at an existing source if the increase does not exceed the operating design capacity of the source, unless that change is prohibited under any federally enforceable permit condition established after January 6, 1975 pursuant to 40 Code of Federal Regulations, 52.21 (1990) or under regulations approved pursuant to 40 Code of Federal Regulations, Part 51, Subpart I or 40 Code of Federal Regulations, 51.166 (1990); [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] C. An increase in the hours of operation at an existing source, unless that change is prohibited under any federally enforceable permit condition established after January 6, 1975 pursuant to 40 Code of Federal Regulations, 52.21 (1990) or under regulations approved pursuant to 40 Code of Federal Regulations, Part 51, Subpart I or 40 Code of Federal Regulations, 51.166 (1990); [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] D. Use of an alternative fuel or raw material if the source is designed to accommodate that alternative fuel or raw material and if prior to January 6, 1975, the source is licensed to use that alternative fuel or raw material; or [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] E. Replacement of an air pollution control apparatus if the replacement is found by the department to be the best practical treatment for the emission. [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).] [PL 1991, c. 384, §12 (NEW); PL 1991, c. 384, §16 (AFF).]