Congressman Morgan Griffith (R-VA) has introduced a discussion draft of a bill that proposes to revise the definition of “modification” in the Clean Air Act (CAA) to “clarify when a physical change in, or change in the method of operation of, a stationary source constitutes a modification or construction.”

Under current law, EPA determines whether a change at an existing facility is a “modification” that requires new source review (NSR) by looking at whether the change increases the annual emission rate of an air pollutant. Under Congressman Griffith’s proposal, a change at an existing facility will only be a “modification” if it results in an increase to the hourly emission rate of an air pollutant. This change is significant because it would enable facilities to make changes that would allow them to operate for longer hours, thus increasing annual emissions, as long as the hourly emissions don’t increase.

The proposed bill also makes clear that the term “modification” does not include changes to an existing stationary source that reduce the amount of any air pollutant or that are designed to restore, maintain, or improve the reliability or safety of the source.

At the May 16, 2018, Energy and Commerce Committee Subcommittee on the Environment hearing, William Wehrum, EPA Assistant Administrator for Air and Radiation, told the subcommittee that he strongly supported the proposed bill. The Democrats on the subcommittee opposed the proposal and ranking member Frank Pallone, Jr. (D-NJ) made a statement critical of the proposed bill:

The ultimate test for any legislation to reform the NSR program is simply this: will it reduce air pollution? By that test, this bill fails. There is no doubt this bill will increase pollution. Republicans are simply resurrecting previously rejected ideas promoted during the Bush Administration by two of today’s witnesses: Assistant Administrator Wehrum and Mr. Holmstead. Together, they have worked for years to undermine the NSR program.

The current definition of “modification” for the NSR program is found at 42 U.S.C. § 7411(a)(4):

The term “modification” means any physical change in, or change in the method of operation of, a stationary source which increases the amount of any air pollutant emitted by such source or which results in the emission of any air pollutant not previously emitted.

Congressman Griffith’s discussion draft proposes the following, revised definition:

(A) The term “modification” means any physical change in, or change in the method of operation of, a stationary source which increases the amount of any air pollutant emitted by such source or which results in the emission of any air pollutant not previously emitted. For purposes of the preceding sentence, a change increases the amount of any air pollutant emitted by such source only if the maximum achievable hourly emission rate of an air pollutant for such source after the change is higher than such maximum achievable hourly emission rate for such source during the 10-year period immediately preceding the change.

(B) Notwithstanding subparagraph (A), the term ‘modification’ does not include a change at a stationary source that—

(i) reduces the amount of any air pollutant emitted by the source per unit of output; or

(ii) is designed to restore, maintain, or improve the reliability or safety of the source, except when the change increases the maximum achievable hourly emission rate of any air pollutant for the source relative to such rate during the 10-year period immediately preceding the change and the Administrator determines that such increase is harmful to human health or the environment and that the change is not environmentally beneficial.

This proposal is in its initial stages and the prospects of this or a similar bill emerging from committee and passing the House and Senate are uncertain.