Modification
Modification means any physical change in or a change in the method of operation of, an existing source which increases the amount of particulate matter emitted by that source. The following shall not, by themselves, be considered modifications: (1) Maintenance, repair, and replacement which the Regional Administrator determines to be routine for the particular source; (2) An increase in production rate of an existing source, if that increase can be accomplished without a physical change to the source or the Astaris-Idaho facility; (3) An increase in the hours of operation of an existing source, if that increase can be accomplished without a physical change to the source or the Astaris-Idaho facility; (4) Use of an alternative fuel or raw material, if the existing source is capable of accommodating that alternative without a physical change to the source or the Astaris-Idaho facility; or (5) The addition, replacement, or use of any system or device whose primary function is the reduction of an air pollutant, except when an emissions control system is removed or replaced by a system which the Regional Administrator determines to be less environmentally beneficial.