### ITEMS FOR ADDITIONAL DISCUSSION: Summary of Interag ency Working

Comments on Draft Language under EO12866/13563 Inte ragency Review.

Subject to Further Policy Review.

1 | P a g e Environmental Protection Agency (EPA): Proposed Rul e

Protection of Visibility: Amendments to Requirement s for State Plans

RIN 2060-AS55

General Comments:

9) Reviewer recommends providing additional informa tion for when the guidance document is planned to go out related to this rulem aking and general timelines for the draft and final version of the guidance. Is it pos sible to align the draft guidance with the proposed rule or to have overlap within the comment periods?

14) Reviewer does not believe that you need to make this distinction between haze and impairment; haze is a relatively uniform distributi on of pollutants that affects visibility. Contributions to haze are both natural and anthropo genic. Impairment is the relative contribution of anthropogenic haze to total haze. When expressed as a change in deciview levels, “impairment” is defined as the dif ference between total haze and natural
haze.

17) Reviewer recommends clarifying the process for non-Class I states that have sources
that affect downwind states with Class I areas.

19) Reviewer recommends taking comment on specific time frames such 120 days, to consult the FLM prior to a public hearing that woul d be de facto enough time for FLM input. It is unclear what enough time would be for a state to provide an FLM.

20) Reviewer recommends providing timeframes for ho w long the assessment by EPA on progress reports would take and what the procedures would be for the assessment. Also, reviewer recommends providing a negative informal c onsent that any modifications or additional steps by the state would not be required after a certain date after submittal of the progress report.

Specific Comments:

9) Page 50 – Reviewer recommends explaining the cri teria that would be used to evaluate the proposed state methods [for selecting the 20 percent most impaired days] understanding that further guidance will provide ad ditional information.

21) Page 88, § 51.301 – Reviewer recommends revisin g the language to state:

a. Haze Index Deciview index means a value, expressed in deciview (dv), for a day
that is derived from calculated or measured light extinction, such that uniform increments of the index correspond to uniform incre mental changes in perception across the entire range of conditions, from pristin e to very obscured. The deciview

### ITEMS FOR ADDITIONAL DISCUSSION: Summary of Interag ency Working

Comments on Draft Language under EO12866/13563 Inte ragency Review.

Subject to Further Policy Review.

2 | P a g e haze index is calculated based on the following equatio n (for the purposes of

calculating deciview haze index using IMPROVE data , the atmospheric light
extinction coefficient must be calculated from aero sol measurements and an estimate of Rayleigh scattering ):
Deciview Haze index (dv) =10 ln e (b ext /10 Mm −1 ).

34) Page 109, § 51.308(i)(2) – Reviewer recommends revising the section as follows: a. The State must provide the Federal Land Manager with an opportunity for consultation, in person at a point early enough in the state’s technical and policy analyses of its long-term strategy emission reducti on obligation and prior to development of reasonable progress goals planning the development of its longterm strategy so that information and recommendations provided by the Federal Land Manager can meaningfully inform the State’s de velopment of the long-term strategy and at least 60 120 days prior to holding any public hearing or other p ublic comment opportunity on an implementation plan (or p lan revision) or progress report for regional haze required by this subpart. This consultation must include the opportunity for the affected Federal Land Managers to discuss their: