Montana Environmental Review Board Lowers De Minimis Threshold

The Montana Environmental Review Board is currently considering lowering the de minimis Potential To Emit (PTE), above which a State air emission permit is required. The current de minimis threshold, which is 15 tons per year (typ), would be lowered to 5 tpy.

Proposed 17.8.745 MONTANA AIR QUALITY PERMITS--EXCLUSION FOR DE MINIMIS CHANGES
( 1) A Montana air quality permit is not required under ARM 17.8.743 for de minimis changes as specified below:
(a) Construction or changed conditions of operation at a facility for which a Montana air quality permit has been issued that do not increase the facility's potential to emit by more than 5 tons per year of any pollutant except:
(i) through (iii) remain the same.
(iv) any construction or improvement project with a potential to emit more than 5 tons per year may not be artificially split into smaller projects to avoid permitting under this subchapter; and
(v) through (2) remain the same.


Public meetings to discuss this change are scheduled for March 2010.

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