Ron Evans/RTP/USEPA/US

04/30/2008 09:18 PM

	

To

"Lee, Amanda I." <Amanda_I._Lee@omb.eop.gov>

cc

Brian Heninger, darryl weatherhead, fann.neal@epa.gov, "King, Heidi R."
<Heidi_R._King@omb.eop.gov>, Kathy Kaufman/RTP/USEPA/US@epa, Lydia
Wegman, simon.nathalie@epa.gov, Tricia Crabtree/RTP/USEPA/US@epa,
walton.tom@epa.gov

Subject

Re: response to chapter 3 comments









Here are my responses to your chapter 3 comments.   I understand that
you find it difficult to verify that something we added to address a
question of Heidi's is adequate.  Hopefully Heidi will have a chance to
scan them quickly.

page 1

We then explain how this tool was used to estimate the air quality
impacts of each hypothetical emissions control strategy.  Following this
discussion, we summarize the air quality impacts of these hypothetical
control strategies and indicate where they result in attainment with the
alternative target NAAQS levels outlined in Chapter 1

OK

page 1

To assess the air quality impact of the hypothetical emissions controls
implemented under the proposed NAAQS, EPA would ideally use a detailed
air quality model that simulates the dispersion and transport of lead to
estimate local ambient lead concentrations.  

OK

page 1

  However, dispersion models are data –intensive and more appropriate
for local scale analyses of emissions from individual sources.  It was
not feasible to conduct such a large-scale data intensive analysis for
this RIA.  As a result, the simplified analysis developed for this RIA,
while distance-weighting individual source contributions to ambient Pb
concentrations, could not account for such locally critical variables as
meteorology and source stack height.  Instead, EPA developed an air
quality assessment tool to estimate the air quality impacts of each lead
emissions control strategy.  [insert ref. to tool]  

We will reference the air quality assessment tool here.

page 2

footnote 4:  For the purposes of this analysis, airports servicing
piston-engine aircraft that use leaded aviation gasoline are treated as
point sources. We assume X million gallons of aviation gasoline are
being consumed.

I think we can include that number here, it should already appear
elsewhere in the RIA

page 3

For the remaining five rules, we obtained information on their overall
HAP control efficiency from the Federal Register and from EPA's internal
MACT summary data.  Table 3-1 summarizes the control efficiencies found
for each of the eleven MACT rules with available control efficiency
data.  This RIA does not presume additional MACT rules [will be? Will
not be?] promulgated in the future.

This RIA is silent on new MACTs which may reduce Pb, we don't count any
which may occur in the future.

For the remaining five rules, we obtained information on their overall
HAP control efficiency from the Federal Register and from EPA's internal
MACT summary data.  Table 3-1 summarizes the control efficiencies found
for each of the eleven MACT rules with available control efficiency
data.  Due to the uncertainty that future MACTs may cover sources which
have Pb emissions, this analysis does not assume the promulgation of
future MACTs.

page 4

For each source with controls identified in the PM NAAQS RIA, we applied
the control efficiency for the appropriate control technology to its
2002 NEI emissions to produce the new, PM NAAQS-adjusted baseline
emissions for that source.  For this analysis, we assume that these
expected control efficiencies to [increase? Not increase?] in the
relevant time period.

Clarify as follows

For each source with controls identified in the PM NAAQS RIA, we applied
the control efficiency for the appropriate control technology to its
2002 NEI emissions to produce the new, PM NAAQS-adjusted baseline
emissions for that source.  For this analysis, we assume that these
expected control efficiencies to remain constant in the relevant time
period.

Ron Evans

Leader, Air Benefit & Cost Group

HEID/OAQPS/OAR/EPA

Mail Drop C-439-02

919-541-5488

919-541-0839 fax

