### Summary	of	Interagency	Working	Comments	on	Draft	Language	under

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

1 **Environmental Protection Agency (EPA) :**  **Proposed Rule** 

**Cross -**  **State Air Pollution Rule for the 2008 Ozone**  **National Ambient Air Quality Standards**

**RIN 2060 -** **A S05**  **Technical Support Document (TSD): Preparation of Emissions Inventories for the**

**Version 6.2 2011 Emissions Modeling Platform**  **General Comments** 1) Reviewer recommends that given the large number of exceptions, it would help to have a roughl y quantitative estimate of how prevalent these are. For example, the section on spatial surrogates is one place where exceptions are handled clearly , but many other sections do not provide guidance on how important these exceptions are. a. From a bigger picture perspective, it would also be useful to have a brief qualitative discussion early on emphasizing that the models being used are largel y state
- of

- the

- art and thus, while there is likel y significant uncertainty around the estimated emissions inventories, the approach attempts to reduce this uncertainty through careful collection of data and benchmarking. This is an im portant caveat to the approach that should be somewhere. Response: Preparation of emissions inventories for air quality modeling is a complex process. We are continuall y evaluating and improving the methods used to develop the emissions inventories along with the ancillary data that is used to prepare the data for air quality modeling. The modeling performed for this rulemaking used the latest available inventories and ancillary data. **Specific Comments** 1) Page 3

– Reviewer recommends either pointing out where the projection methods will be discussed later in the TSD or discuss those methods briefly here. It looks like they

are discussed in Section 4. a. “ Because projected emission inventories had already been prepared for the year 2018 by the time of the Natural Resources Defense Council v. EPA decision, the projected emissions for some sectors were adjusted to the year 2017 using methods appropriate to those sectors. ” Response : The development of the projected inventories is discussed in Section 4. This is mentioned at the end of Section 1. 2) Page 22

– Reviewer recommends understanding the degree to which the hoteling emission factors were imputed from nearb y counties. Is this persuasive or occasional?

### Summary	of	Interagency	Working	Comments	on	Draft	Language	under

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

2 How far off might the factors be? Response : There were 25 counties that were assigned to use hoteling emission factors from counties other than their standard representative counties. Because the factors were still from similar counties in the same states, the reassignment should not have a significant impact on the results. 3) Page 45 (top)

– Reviewer recommends understanding what criterion was used to decide whether to integrate HAPs into a particular sector. Response : This is discussed in sections 3.2.1.1 and 3.2.1.3 of the TSD . Generall y we integrated sources other than prescribed and wild fires, many point sources

- because the BAFM and VOC could potentially be reported at different processes within a facility thereb y making integration difficult , and sources where the sum of BAFM pollutants was greater than the VOC emissions. There is no need to integrate s ources without emissions of BAFM pollutants. For the sector “othpt” we integrated onl y the C3 marine sources in this sector (see Section 2.4 .2) because HAPs in this sector are derived identically to the U.S. c3marine sector. 4) Page 49 (footnote 16)

– How many select sources and select counties were affected b y this error? Was this number large or small? Response : A portion of the oil and ga s sources in 98 counties were affected. The VOC speciation for these counties was performed based on national profiles instead of region

specific ones. 5) Page 57 (middle)

– How much of the data is imputed with annual mean values? I s this appropriate rath er than using seasonal mean values? Response : We reviewed the version of the correction program more closel y, and note that monthly mean values are used when there is enough data available for that month. Annual average values are only used when there is not enough data for a particular month. The total amount of NO x reduced by this process was 6,600 tons out of 2,000,000 total tons of EGU NO x in 2011. Out of the 4,824 CEMS units, there were 1,344 units with at least one hour adjusted and the total amount of pre

- adjusted NO x emissions at those units was 67,000 tons. 6) Page 65 (top)

– For how many units is it not alway s possible to reallocate excess emissions to hours below the historic maximum and thus the regional fuel

- sp ecific average profile is used to impute the data? The graphs are beneficial, but the reviewer recommends providing a quantitative estimate.

### Summary	of	Interagency	Working	Comments	on	Draft	Language	under

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

3 Response : There were 75 units for which regional profiles were applied because the emissions would not fit belo w the historic maxima. 7) Page 116 (bottom)

– What percentage of the gas/oil play counties are covered by

the AEO? Response : The AEO gas and oil play data covers 302 of 1260 counties within the modeling domain with more than 5 tons of VOC emissions from oil and gas sources

. These counties account for 56% of the VOC and 41% of the NOx emissions from oil and gas - related sources

. 8) Page 152

– Reviewer recommends mentioning that VMT has largel y leveled off in the past several ye ars although it is beginn ing to ris e again, but that the AEO estimates, while showing a continued increase, are still reasonable forecasts because they extend the long

- term trend. Response : VMT trends can be seen at this site: https://www.fhwa.dot.gov/policyinformation/travel_monitoring/tvt.cfm . We concur with the reviewer that in the few years after 2011, VMT was pretty flat, but has shown a 3% increase in the 12 month rolling average for the pe riod ending August, 2015 (see https://www.fhwa.dot.gov/policyinformation/travel_monitoring/15augtvt/15augtvt.pdf )

. The AEO estimates used for this anal ys is were consistent with the long

- term trends that were available at that time

. The VMT projections used for 2017 will be updated with the most recentl y available information to create the 2017 VMT used for the final rule modeling, as the proposal modeling was actuall y s caled back from 2018 values.