Federal Register, Volume 74, Number 9, January 14, 2009, Pages 1871-2292 Page: 1,914
vii, 2292, ii p. ; 28 cm.View a full description of this periodical.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
Federal Register/Vol. 74, No. 9/Wednesday, January 14, 2009/Rules and Regulations
a small amount of early compliance will
occur. Therefore, as further discussed in
response to other comments, the
combination of the Modeling
projections and other WOE elements
were considered and support the
conclusion that the area will attain by
the area's attainment date.
Comment (MC-8): The commenter
indicated that TCEQ intends to reduce
the amount of DERC values included in
the modeling because using the entire
balance of the DERC bank is "overly
conservative based on past usage of
DERCs." The commenter asserted that
DFW's past air quality violations
occurred under scenarios of less DERC
usage. The commenter concluded that
this belies a Weight of Evidence (WOE)
"trend" of improving air quality because
in the future projection nothing is really
changing from the past when violations
occurred.
Response (MC-8): DERCs are banked
emission credits generated by reducing
emissions beyond required levels that
sources can use to exceed certain
emission limits on a temporary basis.
EPA guidance discusses why emission
credits that are being carried in an
emissions bank ought to be included in
modeled projections. It can be important
because these banked emissions come
back in to the air if the banked credits
are used. As a result, if these banked
emissions are not accounted for in the
future projections, the modeling would
under-predict future ozone levels if
some or all of the banked credits are
used. EPA guidance advises a
conservative approach in which all
banked emissions are included in the
modeled future projections. This
conservative approach assumes that the
entire bank would be depleted during
the attainment year. The TCEQ Bank
held 20.4 tpd of NOx DERCs when
TCEQ reviewed the level of credits in
the bank and included the banked
DERCs in their future year modeling.
After finalizing the future year
modeling, TCEQ reevaluated the
inclusion of all of the banked DERCs in
the future projections. TCEQ believed
that the inclusion of the entire balance
of the DERC bank was overly
conservative based on past usage of
DERCs. They wished to include 3.2 tpd,
rather than 20.4 tpd, of banked DERCs
in the future projections. As discussed
previously, Texas committed to adopt a
restriction on DERC usage to ensure that
no more than 3.2 tpd of banked DERCs
will be used in 2009 and as a result
preventing 17.2 tpd of potential
emissions growth. This approval is
conditioned on TCEQ's adoption and
submittal of a complete SIP revision.Consequently, in order for EPA to fully
approve the SIP, the State will need to
have an enforceable rule in place that
would not allow 17.2 tpd of the 20.4 tpd
banked DERCs currently modeled in the
state's 2009 Combo 10 and PDMR 2009
modeling, to be used beginning March
1, 2009.
The modeling submitted May 30,
2007 did include 20.4 tpd of banked
DERCs in the 2009 future projections.
Relying upon the State's commitment to
revise the DERC rule to limit the use of
banked credits to 3.2 tpd in 2009, it is
appropriate to reduce the 2009 future
modeling projections to 3.2 tpd in 2009.
(For the calendar years after 2009, there
will be an enforceable mechanism to
equate to the limit of 3.2 tpd.) EPA
therefore adjusted the modeling
projections in Table 3 of the proposal
(also included in the MOAAD TSD) to
assess the impacts of the revised future
projections. This was done to provide a
modeling projection that reflected the
inclusion of banked DERCs of 3.2 tpd in
2009. This approach is consistent with
what would have been projected if
TCEQ had redone the SIP modeling
with 3.2 tpd for the banked DERCs
instead of the 20.4 tpd that was
included in the Combo 10 and PDMR
2009 modeling. EPA then used the
revised 2009 modeling projections in
conjunction with other modeling based
analysis and WOE considerations in our
review of the entire attainment
demonstration.
The commenter is correct in the
assessment that DERCs have not been
used in the past and past air quality
exceedances did not include any impact
from DERC usage (since DERCs have not
been used in the DFW area). Now, with
the commitment to adopt a restriction
on DERC use, it is not appropriate to
continue with the assumption that all of
the DERCs in the bank will be used in
the attainment year in the future year
modeling.
Because DERC use did not impact
past exceedances (again because DERCs
have not been used in the past), EPA did
not consider the banked DERCs 2009
usage restriction, as part of our
emissions and ambient trends analysis
that we performed in our WOE
evaluation; rather, it is only in the
modeling where it was considered.
Consistent with the commenters
concerns, EPA was careful in our WOE
evaluations and review to not consider
the revised 2009-banked DERCs usage
restriction in our emission trends
analysis and monitoring trends analysis.
For example in Table 5-11 of the
MOAAD TSD, estimating the actual
emission reductions between 2007 and
2009, EPA did not include anyreductions due to the restriction on
DERC usage. Therefore, EPA believes
that we have appropriately considered
the revised banked DERCs tpd usage
restriction in adjusting assumptions
about possible future emissions growth
in the modeling but consistent with the
commenter's concerns, we have not
considered it in evaluating emissions
and monitoring trends (analysis
included in the WOE analysis). For a
full discussion of DERCs and
conditional approval, see the DERCs
comments section below.
Comment (MC-9): The commenter
indicated that EPA's reliance upon the
low 2007 monitor readings is misplaced
since extremely unusual weather, rain
and low temperatures, dominated the
2007 DFW ozone season. The
commenter continued that the first 100+
OF temperature day was not reached
until late August. The commenter
concluded that EPA should not give
TCEQ credit for something achieved
only by the grace of God.
Response (MC-9): We rely on the 2007
monitored air quality levels as part of
our Weight of Evidence analysis. We
investigated the 2007 meteorology to
determine how it compared with the
DFW normal ozone season meteorology.
To help account for all the different
variables that impact the frequency of
ozone we utilized a Meteorological
Adjusted Trends analysis that was done
by EPA personnel at Office of Air
Quality Planning and Standards
(OAQPS) for the DFW area to assess the
ozone conduciveness of the 2007 ozone
season. OAQPS's analysis utilizes
temperature and precipitation data in
addition to several other factors. The
results of this analysis were included in
our proposal, and indicated that overall
2007 was near the normal meteorology
for DFW's ozone season. See Chapter 5,
section 5.15 and Chapter 6, section 6.3
in the MOAAD TSD.
The commenter asserts that the 2007
ozone season was biased low due to the
influence of more rain than normal and
less 100 OF days than normal. EPA
reviewed monthly meteorological
National Climatic Data Center 2007 data
for DFW International Airport (for the
DFW ozone season months of March 1-
October 31). We evaluated average
monthly temperature, monthly average
maximum temperature, and monthly
precipitation. Looking at this
temperature information and
precipitation data, EPA's assessment is
that, while for several months the
precipitation was above average, the
ozone season and the core ozone
months (June-September) were near
normal overall. For more information,
see the Supplemental TSD. Ozoneformation is affected by a number of
1914
Upcoming Pages
Here’s what’s next.
Search Inside
This issue can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Periodical.
United States. Office of the Federal Register. Federal Register, Volume 74, Number 9, January 14, 2009, Pages 1871-2292, periodical, January 14, 2009; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc132871/m1/51/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.