crossed the reporting threshold will not have data from a ``prior
reporting year'' for estimating gas consumption and abatement system
uptime. The commenter recommended that both 40 CFR 98.93(i)(1)(ii) and
(iii) be revised to allow a facility, where a previous reporting year's
data are not available, to estimate annual gas usage and abatement
system uptime based on

representative operating data from a previous period covering 30 days
or more.
    Response: The EPA agrees with the commenter that instances will
occur where there will be no data from a prior reporting year
available. As a result, the EPA is including in the final amendments to
subpart I, the commenter's suggested changes to 40 CFR 98.93(i)(1)(ii)
and (iii) to allow a facility to estimate annual gas usage and
abatement system uptime based on representative operating data from a
period covering 30 days or more, when data from a prior reporting year
are not available, with the exception that the option is only available
for a fab that did not report in the previous reporting year. If there
is an anticipated change in activity for the fab (i.e., in an increase
or decrease in the annual consumption or emissions of any F-GHG)
greater than 10 percent for the current reporting year compared to the
previous reporting year, reporters are required to identify and account
for the change in their preliminary estimate. Reporters must use a
quantifiable metric (e.g., the ratio of the number tools that are
expected to be vented to the stack system in the current year as
compared to the previous reporting year), engineering judgment, or
other industry standard practice.
    The EPA has determined that this exception is necessary so that any
fab that collected and reported data in the previous reporting year is
required to estimate consumption and uptime based on the data from the
previous reporting year. Recognizing that the previous reporting year
may not represent a complete year (i.e., the fab may have started
operations during the previous year), partial data from the prior year
may be used if the reporter accounts for changes in activity. The EPA
established activity changes that are greater than 10 percent for the
current reporting year compared to the previous reporting year, because
it is the same threshold criterion for conducting a re-test under the
stack test method, as discussed in Section II.A.1 of this preamble.
    Comment: One commenter requested that the EPA include ASTM D6348-
03, ``Determination of Gaseous Compounds by Extractive Direct Interface
Fourier Transform (FTIR) Spectroscopy,'' in subpart I as an alternative
to EPA Method 320. The commenter stated that the ASTM method is more
straight-forward than EPA Method 320 and, as such, is easier to
understand/implement. The commenter stated that EPA Method 320 requires
performing a validation of 12 spiked/unspiked pairs in addition to the
three Quality Assurance (QA) spikes whereas ASTM D6348-03 requires only
three analyte spikes to demonstrate acceptable performance. The
commenter noted that when using the ASTM method one loses the ability
to generate compound-specific correction factors should the system not
sufficiently recover the analytes. The commenter indicated that using
the ASTM method will save time during collection and data processing.
The QA spike procedure and recovery requirements for EPA Method 320 and
ASTM D6348-03 are essentially the same. In both methods, one cannot
spike at more than 10 percent of the extracted flow rate and must
demonstrate recoveries within 30 percent of expected amounts,
respectively.
    The commenter stated that testing companies have collected data
using the ASTM method. The commenter noted that although none of these
data involved F-GHG measurements at semiconductor facilities, the ASTM
method has been successfully used in semiconductor fabs for other
determinations (e.g., hazardous air pollutants) and was used in Intel
stack testing for F-GHG emissions conducted in 2011 to support rule
development. The commenter also noted that several existing EPA
regulations list both EPA Method 320 and ASTM D6348-03 as acceptable
methods: The Reciprocating Internal Combustion Engines (RICE) Maximum
Achievable Control Technology (MACT) (40 CFR part 63 subpart ZZZZ) and
the Turbine MACT (40 CFR part 63 subpart YYYY) list both methods.
    Response: We agree with the commenter that ASTM D6348-03 is an
acceptable method and are including it in this final rule. At proposal
the EPA stated that ASTM D6348-03 had been reviewed as a potential
alternative to EPA Method 320 (77 FR 63575). In the preamble to the
proposed amendments, the EPA stated, ``All data and information EPA has
received in support of the stack testing method used EPA Method 320.
Since this industry contains specialized gases in low concentrations,
EPA would prefer to have supporting data prior to approving another
test method. Because of this, we are not proposing this standard as an
acceptable alternative for EPA Method 320 in this proposed rule.''
    Since this rule was proposed, we have revisited this assessment
based on the comments received. We acknowledge that several existing
regulations list both EPA Method 320 and ASTM D6348-03 as acceptable
methods, as noted by the commenter. We also acknowledge the efficiency
of ASTM D6348-03 as compared to EPA Method 320, although it may pose a
greater risk for the need to perform a retest, as discussed below in
this response. However, ASTM D6348-03 is also ``self-validating,'' as
is EPA Method 320, and contains quality assurance procedures that, when
adhered to, provide an acceptable level of confidence in the measured
concentrations. For these reasons, along with the additional
information provided in the comment on testing conducted in
semiconductor facilities, we are allowing in the final rule amendments
the use of ASTM D6348-03, Standard Test Method for Determination of
Gaseous Compounds by Extractive Direct Interface Fourier Transform
Infrared (FTIR) Spectroscopy, as an alternative to EPA Method 320 with
the following requirements:
    (1) The test plan preparation and implementation in the Annexes to
ASTM D6348-03, Sections A1 through A8 are mandatory; and
    (2) In ASTM D6348-03 Annex A5 (Analyte Spiking Technique), the
percent recovery (%R) must be determined for each target analyte
(Equation A5.5).
    The reporter must also follow Section 4.1 of ASTM D6348-03 to
ensure the F-GHG remains in the gas phase. In order for the test data
to be acceptable for a compound, the percent recovery must be between
70 and 130 percent. If the percent recovery does not meet this
criterion for a target compound, the test data are not acceptable for
that compound and the test must be repeated for that analyte (i.e., the
sampling and/or analytical procedure should be adjusted before a
retest). The percent recovery value for each compound must be reported
in the test report, required under 40 CFR 98.94(j)(4), and all field
measurements must be corrected with the calculated percent recovery
value for that compound by using the following equation:
    Reported result = measured concentration in the stack x (100/%R).
As noted by the commenter, the use of ASTM D6348-03 could result in the
loss of the ability to generate compound-specific correction factors if
the system does not sufficiently recover the analytes (i.e., the
percent recovery value is not between 70 and 130 percent). In this
case, the testing facility would be required to perform a retest for
the target analyte. Therefore, although the use of ASTM D6348-03
provides some efficiency, facilities must assume this risk when using
the ASTM method.
    Comment: One commenter noted that a facility may choose to report
emissions as equal to consumption for a gas if consumption of that gas
is less

than 50 kg per year in a fab, if using the default emission factor
method, as specified in 40 CFR 98.93(a). The commenter asserted that,
under the stack testing alternative, a facility should also not be
required to test for a gas that is not one of the listed ``expected by-
products'' if consumption of that gas is less than 50 kg per year in a
fab. To ensure clarity on this point, the commenter requested that the
EPA modify 40 CFR 98.93(a) to state that, if a fab uses less than 50 kg
of a F-GHG in one reporting year, the reporter may calculate emissions
as equal to the fab's annual consumption for that specific gas as
calculated in Equation I-11 of subpart I. If this is done and the stack
testing method under 40 CFR 98.94(j) is used, the commenter stated that
testing for the gas should not be required unless it is one of the
expected by-products.
    Response: In the proposed rule, EPA neglected to update 40 CFR
98.93(a) to clarify that the provision allowing fabs to calculate
emissions as equal to consumption if their fab consumes less than 50 kg
of a F-GHG only applies to facilities using the estimation methods in
40 CFR 98.93(a)(1) and (a)(2). For the stack testing method, our intent
at proposal was to minimize the burden by providing reporters a method
to calculate emissions of F-GHGs used in small quantities that was
similar but not equal to that of the provisions under the default
emission factor method for gases consumed in quantities of less than 50
kg. To achieve this burden reduction, we proposed provisions for
intermittent low-use gases at 40 CFR 98.93(i)(4)(i). Additionally, we
specified under 40 CFR 98.94(j)(1)(ii) of the proposed amendments,
``you must measure for . . . those fluorinated GHGs used as input
fluorinated GHG in process tools vented to the stack system, except for
any intermittent low-use fluorinated GHG as defined in Sec.  98.98.''
We did not intend for the provisions under 40 CFR 98.93(a) regarding
input gases consumed in quantities less than 50 kg per reporting year
to apply to fabs using the stack testing method because they would have
been duplicative of the provisions for intermittent low-use gases
specified at 40 CFR 98.93(i)(4)(i).
    To clarify that reporters may only calculate emissions as equal to
consumption if their fab consumes less than 50 kg of a F-GHG in one
reporting year and they are using default emission factors for that
fab, we have moved the provision from 40 CFR 98.93(a) and placed it in
40 CFR 98.93(a)(1) and (a)(2). We have also clarified the provision by
specifying that the reporter must also include any by-product emissions
of the gas as calculated in 40 CFR 98.93(a).
    Additionally, in our review of the emissions estimation
requirements for intermittent low-use gases for facilities using the
stack testing method in 40 CFR 98.93(i), we have determined that in
some cases, a facility may use an intermittent low-use gas that does
not have associated default gas utilization and by-product formation
rates in Tables I-11 through I-15. For example, if a facility uses
C4F8O in manufacturing semiconductors on 300 mm
wafers, Table I-12 of subpart I does not have applicable default
utilization and by-product formation rate factors. For these cases, we
have included a provision in 40 CFR 98.93(i)(4) for facilities to
calculate emissions of these gases by assuming utilization and by-
product formation rates of zero for those gases. Facilities will also
account for abatement of these gases, if abatement systems are present
on the tools associated with those stacks.
    Comment: Two commenters questioned the applicability of the
definition of the time interval in Equations I-17 and I-18 at 40 CFR
98.93(i)(3)(ii), which specifies that ``each time interval in the
sampling period must be less than or equal to 60 minutes (for example
an 8 hour sampling period would consist of at least 8 time
intervals).'' One commenter observed that the sum of the average
concentrations in Equations I-17 and I-18 are numerically equivalent
whether the minimum time interval is one hour or one minute. The
commenters requested that the requirement for minimum time intervals
(tm) over the duration of the 8-hour (minimum) stack test
either be removed entirely, or be made specific to the use of the FTIR
method.
    The commenters further explained that when the FTIR method is used,
the sampling period time intervals are typically on the order of
minutes, and so the requirement for a minimum of a 60 minute time
interval is easily achieved. However, in the future GC-MS or similar
types of appropriately validated methods may be used that collect
composite samples continuously over the 8-hour sampling period. In
these situations, the EPA requirement as currently worded would
obligate the sampling technician to collect a minimum of 8 one-hour
time-integrated samples. The commenters contended that such an
obligation would be excessive, and would provide little benefit because
the 8-hour composite sample itself provides an appropriate average.
    The commenters requested that 40 CFR 98.93(i)(3)(ii) either delete
the requirement for a minimum time interval, or make it specific to the
FTIR method, by specifying that each time interval in an FTIR sampling
period must be less than or equal to 60 minutes (for example an 8-hour
sampling period would consist of at least 8 time intervals). Another
commenter recommended that the language in the final rule be revised to
allow for continuous 8-hour testing rather than 8 individual one-hour
runs.
    Response: The EPA agrees with comments regarding sampling times
when using the stack test option. The EPA recognizes that in typical
FTIR sampling, which is the method incorporated into the proposed use
of EPA Method 320, the sampling period time intervals are typically on
the order of minutes; however, instead of specifying a potentially
restrictive sampling period (i.e., a 1 minute basis), the EPA chose to
allow facilities and their testing contractors to decide the most
appropriate sampling period. Additionally, the EPA's intention was to
require facilities to collect concentration measurement data that were
representative of the entire 8-hour (or more) sampling period. As a
result, the EPA proposed that concentration measurement data be
collected, at a minimum, on an hourly basis. The EPA agrees with the
commenter that, if a composite sampling method was used to conduct
stack testing, either through the use of an approved alternative method
or through future rule amendments, the requirement to collect a minimum
of 8 one-hour time integrated samples would not apply since the
composite sample itself would provide a time integrated sample. As a
result, the EPA is incorporating the commenters' suggested revision to
40 CFR 98.93(i)(3)(ii). However, the EPA notes that the GC/MS method is
not an approved method in this final rule and thus any reporter
preferring to use that method would need to follow the procedures found
in 40 CFR 98.94(k).
    Comment: Two commenters expressed concern with the requirement to
certify that no changes in stack flow configuration occur between tests
conducted for any particular fab in a reporting year. The commenters
recognized that it is important to ensure that the system is relatively
static over the course of a round of testing, but stated that a
certification of ``no changes'' goes beyond what is necessary and
reasonable. The commenters noted that a fab may readily be able to
certify that no significant changes have occurred over the relatively
short time

required to complete the consecutive testing of multiple stacks.
However, a facility may not be able to certify that no changes occurred
during testing because one or more process tools might have been added
to or subtracted from a stack system during that time period because,
as part of normal operation, a process tool might be disconnected or
added during a week of testing, but such an action should not
invalidate the test. Such an action would not cause a significant
change in emissions, since a single process tool (or small number of
them) would represent a small fraction of the total. The commenter
stated that, in addition, there is typically a time lag between the
time a process tool connection is made and the time the process tool is
up to full production and emissions.
    The commenters proposed that the certification criterion in 40 CFR
98.94(j)(1)(iv) be modified so that reporters must identify any changes
that occurred over the course of testing, including any GHG emitting
process tools newly connected to or disconnected from the system. The
reporter must also certify that no process tools that were in operation
at the start of the test period have been moved to a different stack
during the test period and that no point-of-use abatement systems on
active process tools have been permanently removed from service during
the test period.
    Response: The EPA agrees with the commenters' suggestions regarding
stack flow configuration certification requirements. Our original
intent of requiring reporters to certify that no changes in stack flow
configuration occur between tests was to ensure that emission factors
developed as a result of testing are representative of normal
operations, and to avoid under or over reporting of emissions as a
result of reporters directing emissions from one stack to another stack
between testing of separate stack systems, or by taking process tools
with lower utilization efficiencies offline during testing.
    Based on the information provided by the commenters, the EPA agrees
that the addition and removal of a limited number of process tools to a
stack system is a common occurrence under normal operating conditions.
As a result, we are revising the certification requirement under 40 CFR
98.94(j)(1)(iv) to require reporters to certify that no significant
changes in stack flow configuration occur between tests conducted for
any particular fab in a reporting year. Specifically, reporters must
certify that no more than 10 percent of the total number of F-GHG or
N2O emitting process tools are connected or disconnected
from a stack system during testing. Although the commenters did not
provide a quantitative limit when referring to ``a small fraction of
the total,'' we determined that it is necessary to limit the number of
tools connected or disconnected to a single stack system during testing
to ensure there are no significant changes in emissions. Additionally,
we agree with the commenters' suggestion to require reporters to
certify that no process tools that were in operation at the start of
the test period have been moved to a different stack during the test
period, and that no point of use abatement systems have been
permanently removed from service during the test period. We also agree
with the commenters that any changes during the test period must be
identified. Therefore, we are requiring reporters to document and
record such changes in the emissions test data and report required
under 40 CFR 98.97(i)(3).
    Comment: Two commenters requested that the final rule include a
specific list of by-products that are to be included in the testing
instead of the requirement for a facility-specific analysis of
``expected'' or ``possible'' by products for each series of tests. This
approach would eliminate uncertainty for the facility that the analysis
was sufficient for purposes of the rule. The commenter noted that the
EPA suggested a list of six chemicals that would be treated as
potential by-products: CF4, C2F6,
CHF3, C3F8,
C4F6, and C4F8 (77 FR
63546). The commenter stated that the latest round of data gathering
also found CH2F2, CH3F, and
C5F8 as by-products in some instances. The
commenter recommended that these three gases be added to the list of
``possible'' by-product gases to be tested for under the stack test
alternative. The commenter further recommended that the list of
``expected'' by-product gases, that will be assumed to be present at
half the FDL even if they are not detected, be limited to the five C1
and C2 compounds (CF4, C2F6,
CHF3, CH2F2, and CH3F)
because the four C3, C4 and C5 by-products (C3F8,
C4F6, c-C4F8 and
C5F8) were found in only a handful of tests. The
commenter stated that the four ``possible'' by-products would be tested
for and, if detected, they would be reported as detected and at half
the FDL for any interval in that round of testing where they are not
detected. If not detected, they would be reported as zero.
    A third commenter supported the EPA's proposal to require that all
fabs using the stack testing method test for the most common six by-
product gases (CF4, C2F6,
C3F8, C4F6,
C4F8, and CHF3). The commenter
supported the EPA's rationale that the cost of testing for six, as
opposed to two, of these gases is expected to be low, because the tests
would be conducted at the same time, with the same equipment and
personnel.
    Response: The EPA agrees with the commenters' suggestion to
designate specific F-GHGs as ``expected'' and ``possible'' by-products.
In the final rule, we are adding Table I-17, which includes a list of
expected by-products and a list of possible by-products. Facilities are
required to test for both expected and possible by-products. If
expected by-products are not detected during a round of testing,
facilities are required to assume that they are emitted at one-half of
the FDL. If possible by-products are not detected during a round of
testing, facilities are required to equate their emissions to zero for
that round of testing.
    This approach simplifies the rule, provides certainty for purposes
of implementation, and relieves facilities of the burden of determining
which by-products should be tested for or assumed to be emitted if they
are not detected. By establishing a comprehensive list of by-products
to include in testing, it also avoids routine underestimates of
emissions that could result if a facility did not test for a by-product
that was in fact emitted.
    We agree with the commenter's suggestion to add CHF3,
CH2F2, and CH3F to the list of
expected by-products. With these additions, the list of expected by-
products includes CF4, C2F6,
CHF3, CH2F2, and CH3F.
Based on all the emission factor data available to the EPA,
CF4 was identified as a by-product in 532 instances,
C2F6 in 589 instances, CHF3 in 297,
CH2F2 in 21, and CH3F in seven
instances out of a total of 1,149 data sets.
    The EPA also agrees with the commenters' recommendation to include
the four C3 to C5 compounds (C3F8,
C4F6, c-C4F8 and
C5F8) in the list of ``possible'' by-products in
the final rule. Based on all the emission factor data available to the
EPA, C3F8 was identified in four instances,
C4F6 in three, c-C4F8 in
five, and C5F8 in four of 1,149 data sets.
    Comment: Three commenters asserted that the maximum FDL values in
Table I-10 of the proposed amendments to subpart I have been achieved
in very limited circumstances with specifically enhanced FTIR
measurement systems. The commenters stated that the FDLs are not
achievable with conventional FTIR systems in normal usage. The
commenters noted that stack testing at

three fabs was completed in support of the testing alternative and the
emissions reports appear in the docket and that the proposed maximum
FDLs were not always met. The commenters noted that when the proposed
maximum FDLs were met, it was with customized enhanced measurement
systems. The commenters stated that these maximum FDLs should be either
dropped from the rule or raised substantially. The commenters asserted
that if they are not removed or raised, the number of available testing
contractors and equipment will be severely limited. If the maximum FDLs
are not met during a test and the test results are consequently
considered invalid, very expensive efforts and arrangements for data
gathering will be wasted. In light of these concerns, the commenters
recommended that the maximum FDLs be increased by a factor of five.
With that change, the fully fluorinated gases would have a maximum FDL
of 25 ppbv, SF6 would have a maximum FDL of 5 ppbv, and other F-GHG
would have a maximum FDL of 50 ppbv. These values would be considered
maximum allowable FDLs. However, if stack testing at a site achieves
lower FDLs, the lower FDLs determined for that stack test would be used
for estimating emissions of expected, but not detected gases.
    The commenters stated that allowing facilities to use higher FDLs
would not affect testing results in a significant way. One commenter
provided a comparison of emissions based on stack test results by
Intel, International Business Machines (IBM) and Texas Instruments
Incorporated (TI) using different FDL assumptions (Docket ID. No EPA-
HQ-OAR-2011-0028-0095). The commenter asserted that, based on their
analysis, the impact when accounting for five expected C1 and C2 by-
products is minor and does not change appreciably for the higher FDLs
except in the case of one facility that had very low concentrations in
the stacks resulting from the fact that facility's tools are fully
abated.
    One commenter supported the proposed maximum FDLs, and agreed that
FDLs should be lower for F-GHGs with higher GWPs.
    Response: The EPA acknowledges the industry commenters' concerns
with respect to the proposed maximum FDLs. The FDL is the lowest
concentration at which at which an F-GHG can be detected during a
specific field measurement. The maximum allowed FDL is the
concentration at which an F-GHG should be detectable when the method is
conducted properly and the analytical instruments are used correctly
and of reasonable quality. Maximum FDLs are specified to ensure that
the field measurements of F-GHG emissions are of adequate quality and
accuracy, and that the fraction of total emissions that are below the
FDL (and which have to be assumed to be one-half the FDL) is minimized.
As discussed in the proposed amendments (77 FR 63547), EPA Method 320
requires the specification of maximum FDLs because the FDLs achieved by
a method and analytical instruments can have a significant impact on
the quality of the measurements. Maximum FDLs are necessary because if
the FDL for a F-GHG is too high, it may capture a relatively large
fraction of the fab's emissions of that F-GHG may occur at
concentrations that are lower than what is detectable by the
instrumentation. This results in the uncertainty of the emission
estimates being correspondingly high. Due to this fact, the proposed
amendments required that facilities must use FDLs that are less than or
equal to the maximum FDLs in Table I-10 to reduce the uncertainty
associated with the emissions estimates under the stack test method.
The maximum FDLs in the proposed amendments were based on FDLs achieved
at three different semiconductor facilities and an analysis of the
magnitude of the emissions that would occur (in CO2e) at
various possible maximum FDLs (see docket item EPA-HQ-OAR-2011-0028-
0085, section 5.1.2). The proposed FDLs were generally, though not
always, close to the average FDLs achieved across all three facilities
that submitted FDL information to the EPA.
    The EPA acknowledges the industry commenters' assertion that two of
the three facilities that submitted information on FDLs (see IBM,
Intel, and TI test reports in docket EPA-HQ-OAR-2011-0028) used
enhanced FTIR technology during stack testing and that not all stack
testing contractors have the capability to perform these enhanced FTIR
measurements. The EPA re-analyzed the available information to assess
the FDL levels that were achievable by the facilities using other
accurate and well-maintained FTIR, including a facility that did not
use enhanced FTIR. Upon review of the FDLs included in the three test
reports, we determined that increasing the proposed FDLs by a factor of
four increases the values to a level that should be consistently
achievable by testers using FTIR equipment under EPA Method 320, even
if the tester does not use enhanced FTIR techniques. At these levels
(four times the proposed maximum FDLs), all of the three stack tests
that were conducted in support of the proposed amendments comply with
the final FDLs for each of the F-GHGs specified in Table I-10. In
contrast, only two of the three facilities that submitted data would
have been able to achieve FDLs that were equal to or lower than the
proposed maximum FDLs. We anticipate that the FTIR equipment and
techniques used by these three facilities are representative of what
would be used by the field of reporters and represent accurate and
well-maintained equipment and techniques in the industry. As a result,
the EPA is promulgating revised FDL values in Table I-10 to subpart I
that are equivalent to the proposed values multiplied by a factor of
four. The EPA determined that it was not necessary to increase the
maximum allowed FDLs by a factor of five, as suggested by the industry
commenter, to establish levels that could be achieved by testing
companies using EPA Method 320 because the analysis of data and
information provided to EPA on this topic demonstrated that an increase
by a factor of four represents the appropriate FDL values. The final
FDLs achieve the necessary balance between achievable FDLs and minimum
uncertainty in the emission measurements derived from stack testing.
    The EPA appreciates the support of the one commenter for the
proposed maximum FDLs. However, as explained earlier in this response,
the maximum FDLs were revised since proposal to a level that better
reflects the FDLs that can be achieved by testing companies using the
methods included in the final rule. The EPA would also like to clarify
that the maximum FDLs that were included in the proposed and final rule
were based primarily on the technical achievability of those levels.
The GWP of the corresponding gases was used only to determine the
overall effect on emissions (in CO2e) of the different
maximum FDL, and it was observed that the achieved FDLs were lower for
gases with higher GWPs that were also easier to detect (see EPA-HQ-OAQ-
2011-0028-0085, section 5.1.2).
    Comment: Two commenters supported the proposed provisions to allow
facilities subject to Subpart I to use prior stack testing completed in
support of rule development to establish initial emissions factors
under the stack test alternative, as long as the tests were completed
no earlier than the date 3 years before the date of publication of the
final rule amendments. The commenters noted that stack testing at three
facilities in support of the

proposed rule was completed in 2011. The commenters requested that the
EPA clarify that all data collected during the calendar year 2011
regardless of the month that the final rule is published will meet the
``within 3-year'' criterion for pre-rule data collection.
    One commenter further explained that for testing conducted prior to
the final rule, a fab may not have collected all required data elements
and/or may not have collected all data elements in a manner consistent
with all criteria in the final rule, and abatement systems may not have
been certified in the 2011 testing as specified in the final rule. As a
result, the commenter requested that the final rule be explicit that a
fab may use prior stack test data to set emissions factors under the
stack test alternative if the key substantive requirements were met,
any deviations from the final rule are reported to the EPA and the EPA
provides concurrence with the use of the data. The commenter stated
that in evaluating whether to accept the earlier test results, the EPA
should exercise its discretion to allow the use of data recorded during
earlier testing, even if the procedures used do not match exactly what
appears as a requirement in the final rule.
    Response: The EPA agrees with the commenter's suggestions regarding
the use of data collected in calendar year 2011 in the stack testing
alternative. In the final amendments to subpart I, under 40 CFR
98.94(j)(7), the EPA is clarifying that data collected on or after
January 1, 2011 may be used in the relative standard deviation
calculation in 40 CFR 98.94(j)(5)(ii) if the previous results were
determined using a method meeting the requirements in paragraph 40 CFR
98.94(j)(2). The EPA is also allowing reporters to use data collected
on or after January 1, 2011 but before January 1, 2014, using a method
that did not meet all the requirements of 40 CFR 98.94(j), on a case-
by-case basis, contingent on Administrator (or an authorized
representative's) approval. Reporters would describe any deviations
from the methods and provisions in the final rule and the EPA would
review and approve or disapprove the use of those data in the stack
testing alternative, according to a review procedure that is similar to
that followed for review and approval of an alternative stack testing
method specified in 40 CFR 98.94(k). However, this procedure does not
require the use of EPA Method 301 to validate the prior test data. The
EPA would retain the right to not approve the use of data that does not
meet the data quality requirements in 40 CFR 98.94(j)(7). See 40 CFR
98.94(j)(7) for more details regarding the use of data collected prior
to the promulgation of the final amendments in the relative standard
deviation calculation.
    Comment: One commenter asked the agency to reconsider its proposal
to allow facilities to conduct multiple tests in a single year with the
aim of demonstrating low variability and becoming exempt from annual
testing. The commenter stated that given the magnitude and rate of
change in the semiconductor industry, facilities should, at a minimum,
be required to do annual tests for a period of 3 years before
qualifying for an exemption of up to 5 years. The commenter expressed
concern that the measured emission factors could be stable over a one-
year period but not over a three-year period.
    Response: The EPA agrees with the commenter that it is possible an
emission factor determined from three tests in one year could be
representative of a fab's emissions over a one-year period, but not
over a three-year period. However, the types of factors that could
affect the emissions over a three-year period, such that the emission
factors developed from conducting three tests in one year are no longer
representative, are likely to be the same types of factors that would
trigger the requirements to perform a new test, as promulgated at 40
CFR 98.94(j)(8). Therefore, it is unlikely that a reporter could
substantially change a facility in such a way that the emissions would
change substantially without triggering the requirement to perform a
retest.
    If a facility is required to perform a re-test, the results of that
test will not extend the date of the next scheduled test. If a facility
is required to conduct a re-test, the facility must also use the data
from the re-test and the two most recent previous stack tests to
evaluate whether the facility still meets the criteria to skip annual
testing. If the facility no longer meets those criteria, the facility
must resume testing regardless of when the facility qualified to skip
annual testing. The facility may perform annual testing or may perform
multiple tests in a single year to collect sufficient new data to see
if they again qualify to skip annual testing. Therefore, the option for
facilities to perform multiple emissions tests within the same year
would not allow facilities to use data that are not representative of
current emissions, provided they adhere to the provisions in 40 CFR
98.94(j)(5).
    Comment: One commenter agreed with the list of changes at a fab
included in 40 CFR 98.94(j)(8) that trigger the requirement that a
stack system be retested. The commenter suggested additional fab
changes identified in the context of the triennial technology
assessment report required under 40 CFR 98.96(y) that should also
trigger retesting (e.g., implementation of new process technologies,
introduction of new tool platforms, and introduction of new processes
on existing platforms). Another commenter stated that potential new
process technologies that would change the nature of the emissions of
GHGs from semiconductor manufacturing would trigger one or more of the
six triggers for retesting included in 40 CFR 98.94(j)(8). The second
commenter predicted that the triggers that would most likely be
affected by new process technologies would be the change in the
consumption of a F-GHG by more than 10 percent of the total annual F-
GHG consumption (in CO2e), the change in the consumption of
an intermittent low-use F-GHG, or a decrease by more than 10 percent in
the fraction of process tools with abatement systems.
    Response: Based on the comments on the proposal, the EPA has
concluded that the re-test triggers that were proposed and promulgated
under 40 CFR 98.94(j)(8) are adequate to capture changes in fab
emissions as a result of new process technologies, new tool platforms,
and new processes on existing platforms. These types of changes are
already accounted for by the criteria that that are specified in 40 CFR
98.94(j)(8), and no new criteria have been added in the final rule.
However, the EPA has included additional recordkeeping requirements in
40 CFR 98.97 to verify compliance with the factors that would trigger a
retest. Specifically, we are revising 40 CFR 98.97(i)(3) to require
records of the identity and total annual consumption of each gas
identified as an intermittent low use F-GHG, to verify any change in
the consumption of an intermittent low-use F-GHG that was not used
during the emissions test and not reflected in the fab-specific
emission factor, such that it no longer meets the definition of an
intermittent low-use F-GHG. We are also adding a new provision at 40
CFR 98.97(i)(9) to require records of the total number of tools at each
stack in the fab which, along with the number of abatement systems, is
needed to verify if a facility has a decrease by more than 10 percent
in the fraction of tools with abatement systems compared to the number
during the most recent emissions test.

2. Revisions to the Default Gas Utilization Rates and By-Product
Formation Rates for the Plasma Etch Process Category for Facilities
That Manufacture Semiconductors
    Comment: One commenter provided additional input on the merging of
the default gas utilization and by-product formation rates for wafer
clean and etch processes. The commenter provided data from industry
publications for the total F-GHG usage for these processes. The
commenter stated that wafer cleaning is between 0.8 and 2 percent of
total 200 mm F-GHG usage. The commenter stated that five gases are used
in 200 mm wafer cleaning. The commenter noted that four of the five
gases are also used in 200 mm chamber cleaning and etch processes, and
one gas is used in etch and wafer cleaning. The commenter asserted that
because wafer cleaning is a low percentage of 200 mm F-GHG usage,
combining wafer cleaning and etch processes will have a minor impact on
the accuracy of the emissions estimates under Subpart I.
    Response: The EPA proposed to combine the etch and wafer cleaning
categories, which could reduce the apportioning required of a facility
and potentially reduce gas apportioning errors if the facility uses the
same F-GHGs for wafer cleaning and etch. Facilities using 150 mm and
200 mm wafers typically need to apportion three to five gases between
the plasma etch and chamber cleaning process types/subtypes. As noted
by the commenter, five gases are typically used in 200 mm wafer
cleaning (C2F6, CF4, CHF3,
NF3, and SF6) and each of these gases are also
used in either the etch and/or chamber cleaning process types.
    The effect of gas apportioning errors on GHG emissions accuracy
depends upon the difficulty of the gas apportionment by gas and process
type/subtype. For example, no apportionment error would be present for
gases used only in one process and little apportionment error would
result if only small portions of gas use are allocated to processes
other than the dominant one. The overall impact of apportioning on the
accuracy of the GHG estimate depends on each gas's GWP value and its
contribution to the total fab emissions. As noted in the preamble to
the proposed amendments to subpart I (77 FR 63552), the gases used for
plasma etch and wafer clean have similar gas utilization rates and by-
product formation rates. Furthermore, as provided in the ``Technical
Support for Modifications to the Fluorinated Greenhouse Gas Emission
Estimation Method Option for Semiconductor Facilities under Subpart I''
(see Docket Id. No. EPA-HQ-OAR-2011-0028-0083) and supported in the
data provided by commenters, wafer cleaning is expected to represent a
small percentage of total gas consumption for facilities manufacturing
wafers 200 mm or smaller. Because the gases used in wafer cleaning at
200 mm facilities represent only a small portion of total fab
emissions, the EPA does not anticipate that merging the etch and wafer
clean subcategories will greatly impact the accuracy of GHG emission
estimates. Therefore, the final rule will combine the wafer clean and
etch process types for fabs using 150 and 200 mm diameter wafers. The
final rule will also combine the wafer clean and etch process types for
fabs using 300 and 450 mm diameter wafers.
    Comment: Several commenters supported the use of default gas
utilization rates and by-product formation rates under subpart I. One
commenter claimed that the method allows for the use of emissions
factors and abatement efficiency factors that have been derived from
extensive testing and provide the basis for high quality emissions
estimates without disruptive testing in the fab environment where
operating uptime is critical to the productivity of the fab. The
commenter stated that much of the data used to derive the factors in
the proposed rule came from the efforts of the semiconductor industry
in advance of the proposed rule. The commenter noted that SIA and ISMI
continued emissions factor data collection activities during settlement
discussions to improve the representativeness of the emissions factor
database.
    The commenter provided 168 additional gas utilization and by-
product formation rate data sets, noting that the data were provided by
semiconductor process equipment suppliers and device manufacturers for
200 mm and 300 mm plasma etch equipment. The commenter asserted that
the 2012 data closed gaps in the emissions factor database and allowed
for establishment of default emission factors for every gas used in
semiconductor plasma etch processes, as identified in a 2011 ISMI
survey. The commenter provided an analysis of the integrated database
and the resulting emission factors (see Docket Id. No. EPA-HQ-OAR-2011-
0028-0095). The commenter further stated that a minimum of 23 data sets
for each gas were used to develop emission factors for each gas that is
1 percent or more of the total F-GHG usage for each wafer size. The
commenter stated that the four gases with four or less data sets are
either not used for etch or are much less than 0.1 percent of total F-
GHG usage for that wafer size.
    The commenter also provided a comparison of default emission
factors based on the added data to the default emission factors in the
2012 proposed rule (EPA-HQ-OAR-2011-0028-0095). The commenter noted
that when a large dataset was previously available to establish the
proposed revised default emission factors, the addition of the 2012
data did not appreciably change the proposed revised default factors.
The commenter also provided a list of the revised default by-product
emission factors for 200 mm and 300 mm etch based on the additional
data (EPA-HQ-OAR-2011-0028-0095). The commenter noted that several by-
products, namely C5F8, CH3F, and
CH2F2, that were not detected previously, were
observed during this round of testing. The commenter reasoned that this
may be the result of data being provided for tool and gas combinations
that were not previously tested. The commenter suggested that these new
by-products would have no discernible effect on reported emissions
because the by-product emission factors are small and the GWPs of these
gases are less than 200.
    Response: The EPA thanks the commenter for the additional data
provided during the public comment period. The EPA incorporated the
provided data into the existing etch process type emissions factor
database to calculate new and revised gas utilization and by-product
formation rates for the final rule. The EPA used the emission factor
calculation methodology outlined in the proposed rule to evaluate the
new and revised emission factors. Specifically, the EPA:
    (1) Used a simple arithmetic averaging method to develop default
utilization and by-product emission factors by gas for the etch process
type; and
    (2) Used the ``all inputs gas'' convention for assigning by-product
formation rates (emission factors) for etch gases. This convention
assigns by-product emissions to input F-GHGs used in a process by
dividing the measured mass emitted of a specific by-product by the
total mass of all input F-GHGs for that process and assigning this by-
product factor to each input F-GHG used in that process. This is the
same approach used in developing the proposed revised emission factors
in the 2012 proposed rule.
    For semiconductor manufacturing using 200 mm wafers, the data
provided by the commenter added one gas utilization rate for
semiconductor manufacturing for which no data were

previously available (for C5F8 as an input gas)
and revised the utilization rates of nine F-GHGs. For semiconductor
manufacturing using 300 mm wafers, the new data added two gas
utilization rates, for C3F8 and CH3F,
and revised the utilization rates of 10 F-GHGs.
    The new data also provided 75 revised by-product formation rates,
including three new by-products not previously identified (for the by-
products C5F8, CH3F, and
CH2F2).
    The EPA's analysis of the new emission factor data for input gases
and by-product gases is included in the docket for the final rulemaking
in the item entitled ``Technical Support for Final Modifications to the
Fluorinated Greenhouse Gas Emission Factors and By-Product Formation
Rates for Semiconductor Facilities under Subpart I'' (EPA-HQ-OAR-2011-
0028).
    Comment: A commenter noted that in the preamble to the proposed
rule (77 FR 63551), the EPA asked for an explanation of the zeros in
the data previously collected and provided by SIA and used by the EPA
to calculate the default emissions factors. The commenter noted that
because the data came from a wide range of sources, the commenter
cannot be certain of the basis of the zero entries in the data base.
The commenter suggested that the zeros most likely mean that a gas was
not present above the detection limit achieved during the test, but
there is a small chance that the tester did not look for the gas. The
commenter stated that in the interest of conservative emissions
reporting, they agree that it is appropriate to err on the ``high
side'' by determining by-product factors only using the non-zero
results. The commenter stated that the default factors would be less if
the zeros were included in determining the average emissions factor and
that it is likely that the default by-product emissions factors would
also be lower if the zeros were included at half the detection limit,
using the practice proposed by the EPA for measuring the presence of
certain gases when implementing the stack alternative. The commenter
stated however, that it is not possible to do so for the default by-
product emissions factors based on the data collected by the commenter
because the field detection limits (FDLs) for each test were not
previously collected. For these reasons, the commenter recommended that
the EPA retain the approach used in the proposed rule for determining
default by-product emissions factors from the available data.
    Response: The EPA agrees with the commenter on the method for
averaging the available by-product emission factor data and with the
likely basis for the zeros in the data collected. The EPA considered
averaging the available emissions data using either the zeros in the
available data or half the detection limit for the by-product gas if
the data gatherer looked for, but did not detect, by-product emissions.
However, because it is not apparent that the basis of the zeros in the
data represent instances where a by-product was looked for, but not
detected, and because the field detection limits for each test were not
previously collected, the EPA agrees with the commenter that the
averaging approach used in the proposed amendments to subpart I is
appropriate. In determining revised default by-product emission factors
for the final rule, the EPA used the simple arithmetic mean of all
available non-zero by-product emission factor data for each gas, wafer
size, and process-type or subtype using the revised etch emissions
database. If additional by-product emission factor data are made
available to the EPA in the future, and those data include instances
where a by-product was looked for, but not detected, and field
detection limits are provided, the EPA may reassess the by-product
emission factor calculation methodology.
    Comment: One commenter stated that Equation I-15b should be
eliminated. The commenter stated that the calculated abatement unit
uptime for the process gases for which the abatement system is
certified for treatment is the same for by-product treatment. The
commenter further noted that where the unit is not effective for one or
more of the by-product gases, it will not be certified to treat that
gas and the DRE will be zero, and where a unit has a lower uptime for a
subset of the certified gases, that lower, gas specific uptime would be
applied to applicable by-product gas(es). The commenter stated that
companies will have abatement uptime data organized by input gas type,
and the uptime for the input gases will match the uptime for the by-
product gases. The commenter contended that there is no need to perform
a separate calculation of abatement system uptime for by-product gases,
and enabling companies to calculate uptime by the combination of input
and by-product gas would simplify calculations and recordkeeping while
not reducing the accuracy of the uptime data.
    Response: The EPA agrees with the commenter that only a single
uptime equation is needed and has removed Equation I-15b from the final
rule, and modified Equation I-15a (Equation I-15 in the final rule) so
that it is applicable to both abatement systems treating input gases
and by-product gases.
    In developing the proposed rule amendments, the EPA developed
separate equations under the assumption that the population of
abatement systems treating a particular input gas could be different
from the population of abatement systems treating a by-product gas
because not all input gas and process combinations create the same by-
product gases. However, the uptime calculated by Equations I-15a and I-
15b is used in Equations I-8 and I-9, respectively, and in those latter
two equations, emissions are tied to the consumption of the same input
gas, Cij. Therefore, uptime only needs to be calculated for the
abatement systems receiving the input gas, Cij, and separate uptime
does not need to be calculated for the by-product gas. As the commenter
correctly notes, where an abatement system is not certified for the
treatment of a particular by-product gas from an input gas, the DRE for
that gas will be zero, and the uptime of the system will be irrelevant.
    The EPA has also made the other conforming changes in other
sections of the final rule to remove the references to Equation I-15b
as noted by the commenter.
3. Apportioning Model Verification for Facilities that Manufacture
Electronics
    Comment: One commenter noted that in the proposed amendments at 40
CFR 98.94(c)(2)(iv), the period of representative gas consumption used
to verify the apportioning model when using the stack method would be
required to end exactly on the day that stack testing is completed. The
commenter noted that most gas use accounting is managed on a monthly
basis, so it would not be practical to end the period on the same day
that testing is completed. The commenter suggested that the rule should
allow the apportioning model to be validated over a period that ends
between the first and last day of the accounting month(s) in which the
stack testing takes place because this would simplify the data
collection for locations without significantly affecting the accuracy
of the gas use estimates used in the verification. The commenter noted
that 40 CFR 98.94(c)(2)(i), which is referenced by 40 CFR
98.94(c)(2)(iv), allows the representative period to be `` . . . at
least 30 days but not more than the reporting year.'' Enabling
locations to use an end date within the accounting month, instead of
tying it to the last day of stack testing, would simplify the data
collection without

introducing error, particularly if the verification period is more than
90 days. The gas usage accounting systems at some semiconductor
facilities are based on accounting months (e.g., 13-4 week months)
rather than calendar months. The commenter asked that 40 CFR
98.94(c)(2)(iv) be revised to allow that the time period specified in
40 CFR 98.94(c)(2)(i) ends on a day between the first and last day of
the accounting month for the period that includes the last day the
facility performs stack testing, or that is a defined period ending on
the last day of sampling event.
    Response: The EPA agrees with the commenter that it is reasonable
that the period selected for apportioning model verification, when a
facility is using the stack testing method, should be allowed to
coincide with the accounting period used at the fab for normally
tracking gas consumption, and should not be tied to the day on which
testing is completed. The EPA's proposal was intended to ensure that
the representative period selected to validate the apportioning model
coincided with the period during which the stack testing was being
performed to ensure that gas consumption during stack testing was being
estimated as accurately as possible. The commenter's suggested change
to 40 CFR 98.94(c)(2)(iv) would achieve the same objective and would
also be consistent with the facility's normal accounting periods for
gas usage.
4. Calculating N2O Emissions for Facilities That Manufacture
Electronics
    Table I-8 of subpart I provides two default N2O emission
factors. One factor is for CVD processes using N2O, and the
other is for the aggregate of all other N2O-using
electronics manufacturing processes. The EPA proposed to revise the
default N2O emission factor in Table I-8 of subpart I for
the aggregate of the ``other'' (non-CVD) N2O-using
manufacturing processes (77 FR 63560). The current default emission
factor is 1.0 kg of N2O emitted per kg of N2O
consumed. The proposed emission factor was 1.14 kg of N2O
emitted per kg of N2O consumed, and represented an average
of the stack emission factors for N2O (total N2O
emissions/total N2O consumption) measured in nine tests at
three fabs. (See EPA-HQ-OAR-2011-0028-0084, section 5, for a summary of
the data used to develop the proposed default emission factor.) The EPA
did not propose to revise the N2O emission factor for CVD
processes. The EPA specifically sought comment on the existing data and
analysis supporting the proposed emission factor, and requested
additional data and analysis. The preamble noted that the average
N2O emissions from the stack testing appeared to be greater
than the N2O consumption and, as a result, the emission
factor is greater than 1.0. The preamble also noted that the proposed
emission factor was based on emissions associated with total
N2O consumption, rather than just emissions and consumption
data associated with non-CVD applications (which were not available to
the EPA). Thus, the EPA noted at proposal that when these data were
applied only to non-CVD N2O consumption, they may not have
fully compensated for the unknown N2O source that resulted
in an emission factor greater than 1.0, and that EPA did not have an
explanation for the apparent creation of N2O. The preamble
requested comment on the existing data and analysis supporting the
proposed revised default emission factor, and noted that the EPA would
consider new information and data submitted by commenters in developing
the final default emission factor.
    Comment: No commenters offered an explanation for the apparent
creation of N2O reflected by the average N2O
emission factor greater than 1.0, nor did any commenters provide any
additional N2O emission factor data.
    Two commenters recommended that the N2O process
categories should be aligned with the F-GHG categories to ensure
consistency and reduce the potential for confusion. The commenters
suggested that the use of the term CVD (chemical vapor deposition) in
the current rule does not align with the established process categories
of chamber clean and/or plasma etch/wafer cleaning. The commenters
proposed that the EPA replace the terms ``chemical vapor deposition''
or ``CVD'' where they appear in Section 98.93(b)(1) and Table I-8 with
the following phrase: ``processes associated with the chamber clean
process type.'' The commenters noted that N2O is sometimes
used in the deposition processes associated with the in-situ, remote,
and thermal chamber cleaning tools and recipes, and suggested that the
application of N2O in these circumstances is very similar
and the utilization rates are consistent. The commenters suggested that
the EPA should continue to categorize those N2O-using
processes that do not fall into the processes associated with the
chamber clean process type as ``other manufacturing processes.''
    Response: The EPA did not receive any new N2O emission
factor data that can be used to resolve the uncertainties associated
with the data used to develop the proposed emission factor for the
other N2O-using manufacturing processes of 1.14 kg of
N2O emitted per kg of N2O consumed. As stated
above, at proposal the EPA had data from nine tests of N2O
emission rates from three fabs owned by two companies. Six measurements
were from one fab, two measurements were from a second fab, and one
measurement was from a third fab. The second and third fab were owned
by the same company. In four of the nine measurements, N2O
emissions were greater than N2O consumption, and the
emission factors were highly variable both within and across fabs,
ranging from 0.34 to 1.89 kg emitted per kg consumed. The EPA could not
explain the cause of the emission factors that are greater than 1.0.
Given the highly variable nature of the measured emission factor data,
the small number of tests, and the lack of information on the specific
processes represented by those data, the EPA is not confident that
those data accurately represent emissions from non-CVD processes used
in electronics manufacturing. Therefore, the EPA is not finalizing the
proposed change to the emission factor that was based on those data.
The N2O emission factors will remain as they are in the
current Table I-8 of subpart I. The emission factor for CVD will remain
at 0.8 and for all other N2O using processes at 1.0 kg of
N2O emitted per kg of N2O consumed. The EPA does
not have, at this time, a sufficient amount of data to support any
changes to these emission factors.
    The EPA is also not accepting the suggestion at this time to revise
the N2O categories in Table I-8 of subpart I to include CVD
and chamber clean under a single category of ``processes associated
with the chamber clean process type.'' The EPA does not have data at
this time to demonstrate that the utilization rates in the deposition
processes associated with the in-situ, remote, and thermal cleaning
process types are similar to those in the CVD process type and should,
therefore, be combined into a single category.
    The EPA will continue to work with industry to understand these
N2O-emitting processes and to gather additional data and
information for potential future revisions. One potential avenue for
gathering information and data will be through the triennial technology
assessment report specified in 40 CFR 98.96(y), although the EPA may
accept new data at any time they are available.

5. Abatement System Destruction and Removal Efficiency (DRE) for
Facilities That Manufacture Electronics
    Comment: One commenter suggested revising the definition of
abatement system to clarify which abatement systems are covered under
the requirements in Subpart I as follows: ``Abatement system means a
device or equipment that is designed to destroy or remove F-GHGs and
N2O in waste exhaust streams from one or more electronics
manufacturing production processes.''
    The commenter explained that there are abatement units installed in
fabs for purposes other than GHG abatement, including but not limited
to solids removal, pyrophoric destruction, and volatile organic
compound (VOC) emissions control. The commenter noted that under the
current rule language, it appears that if any of the regulated GHGs are
exhausted to these units, one is technically required to manage them
under the requirements of Subpart I. These types of units are not
designed for F-GHG treatment and any treatment which does occur is
incidental and would not be capable of being certified under the rule
requirements. The commenter stated that inclusion of the ``designed
to'' phrase clarifies that only systems designed to treat F-gas
emissions are covered by the requirements of the regulation.
    Response: The EPA agrees with the commenter and has revised the
definition of abatement system as suggested by the commenter. However,
in response to other comments, the EPA has also revised the definition
to include abatement systems for which the F-GHG or N2O DRE
has been measured according to 40 CFR 98.94(f). The EPA recognizes that
some systems that were not specifically designed for F-GHG or
N2O abatement may still achieve substantial F-GHG or
N2O abatement for certain gases and some facilities may wish
to account for this abatement in calculating emissions.
    The EPA notes that only data from abatement systems that were
specifically designed to abate F-GHG or N2O emissions were
used to develop the final default DREs. As a result, those default DREs
will be applied only to those systems specifically designed to abate F-
GHGS or N2O, as appropriate, under the requirements of
subpart I.
    To account for abatement systems that may have been installed to
abate other gases, such as volatile organic compounds or hazardous air
pollutants, but achieve some level of F-GHG abatement, the final rule
will also allow facilities to account for the DRE of systems if a site-
specific DRE has been measured as specified in 40 CFR 98.94(f).
    Because the final rule allows facilities to account for the DRE of
systems that are specifically designed for F-GHG or N2O
abatement, and for those for which a site-specific DRE has been
measured, including those that were not designed for F-GHG or
N2O abatement, the definition of abatement system in the
final rule has been modified to account for both situations.
    In each situation, facilities will be required to certify these
systems according to the applicable requirements of 40 CFR 98.94(f),
include these systems in the abatement system inventory included in the
annual report (40 CFR 98.96(q)), and meet the recordkeeping
requirements of 40 CFR 98.97 for abatement systems.
    Comment: One commenter noted that the abatement system count in a
particular gas and process type will change over time. The commenter
asserted that a change in the number of systems may lead to uncertainty
in the number of abatement systems that should be included in the
random sampling abatement system testing program specified in 40 CFR
98.94(f)(4)(ii)(A). In the proposed rule amendments, the facility must
test 20 percent of systems in a given gas and process combination in
the first 2 years (a minimum of 10 percent per year until reaching a
minimum of 20 percent), and at least 15 percent in each following 3-
year period (a minimum of five percent per year until reaching at least
15 percent). The commenter requested that the final rule clarify the
number that should be used as the basis for the percentages and
suggested that it should be based on the number present at the time the
testing begins for the given period of the testing. The commenter
explained that if five percent are tested a year and units are added or
removed between that year and the next, that round of testing still
counts as five percent.
    Response: The EPA agrees with the commenter that the final rule
should clarify the number of abatement systems to be tested on a yearly
basis, because the abatement system count for a particular gas and
process type could change over time. The final rule specifies that
reporters determine the number of abatement systems to be tested based
on the average number present over the period required to test the
minimum percent of systems for a gas and process type. For example, if
a facility completes testing of the minimum 15 percent in a single year
instead of three years, then the number tested would be based on the
systems present in that year. If testing were completed over 3 years,
the number tested would be determined based on the average number in
that three year period. If a facility adds abatement systems during
that time, they may need to increase the number tested in the second or
third year to meet the minimum for the 3-year average. If a facility
tested the minimum of 15 percent in 1 year, and then added systems in
years 2 and 3, the higher number of systems would be accounted for in
the number to be tested in the next 3-year period.
    We are not adopting the commenter's suggestion that reporters
should determine the number of abatement systems to be tested for the
3-year period based only on the count at the beginning of testing.
Allowing a facility to use only the number of abatement systems at the
beginning of the period may result in a non-representative site-
specific DRE for a particular gas and process type/sub-type
combination, especially if a facility began a program of adding
substantial numbers of abatement systems after the first year of the
RSASTP. Facilities that have not completed testing when abatement
systems are added must include those abatement systems in determining
the number to be tested. For example, if a facility installs abatement
systems in years 2 or 3, and is still testing DRE in those years, then
the number of systems tested must be adjusted to reflect the increased
number of systems. However, if testing of 15 percent of systems is
already completed for that 3-year period, the facility does not need to
resume testing to account for the change in percentages. If a facility
has completed testing for that period and then installs abatement
systems for a gas and process combination that was not included in the
testing, the facility would have the option of testing the DRE for that
newly abated gas and process combination, or using the default DRE
until that gas and process combination is included in the next round of
testing.
    Comment: One commenter requested that the EPA add a sentence to the
end of 40 CFR 98.94(f)(4)(iii) to clarify that all DRE test data
collected in 2011, or later, will qualify for use in determining site
specific DREs for the locations where the testing occurred.
    Response: The EPA agrees with the commenter regarding the use of
data collected in calendar year 2011. In the final rule under 40 CFR
98.94(f)(4)(iii), the EPA is clarifying that data collected on or after
January 1, 2011 may be used

in the average DRE calculation if the previous results were obtained
following the requirements in 40 CFR 98.94(f)(4)(i).
    Comment: One commenter suggested changes to the provisions under 40
CFR 98.94(f)(4)(v) regarding the use of a DRE value below the
manufacturer-claimed DRE measured when the abatement system is not
installed, operated, or maintained in accordance with the site
maintenance plan. The commenter proposed two options:
    (1) Include the measured DRE for the unit in the calculation of the
site-specific DRE for the gas and process combination. The measured DRE
for that unit must be included in the site-specific DRE average until
corrective action is completed and the abatement system is retested.
Corrective action must be completed in a reasonable time, but retesting
can be deferred to the next testing period. Any affected abatement
units that are being re-tested must be in addition to the randomly
selected minimum sample for that testing period, or
    (2) Exclude the measured DRE for that unit in the site-specific DRE
average until corrective action is completed and the abatement system
is retested. However, in that instance the abatement system will be
treated as down for purposes of calculating abatement system uptime
until the retest is completed.
    The commenter claimed that allowing inclusion of the lower DRE in
the site-specific average would enable a facility to choose whether it
wants to accept a lower DRE for its site-specific value for a given gas
(even though a low DRE value will have an inordinate impact on the
site-specific DRE because the average is based on measurements from 35
percent of the units), or whether the facility wants to manage its
uptime number for different units. The commenter stated that the
benefit of choosing the lower DRE is being able to maintain a
consistent uptime across all the gases, simplifying management of the
calculations.
    Response: The EPA agrees with the commenter that facilities should
have the flexibility to either include or exclude DRE data from a
system that is operating outside the established parameters for that
system and not meeting the definition of ``operational mode'' in 40 CFR
98.98. However, the EPA disagrees with the commenter's implication that
the facility can treat that system as meeting the definition of
operational mode, even if it is not, for the purposes of calculating
uptime. If a facility has abatement systems that are operating outside
the established parameters and not meeting the definition of
``operational mode'', the facility must treat that system as being
``down'' for purposes of calculating uptime and emissions, even if the
facility is using the lower measured DRE in calculating an average
measured DRE. This approach would allow a facility to use a lower DRE
value and avoid the expense of immediately repeating a system's DRE
measurement, but it would also recognize that facilities should not
treat an abatement system as meeting the definition of ``operational
mode'' when it is operating outside established parameters and could
have variable and unpredictable performance. Therefore, in both
situations suggested by the commenter, the final rule requires that the
facility treat the system as being down for purposes of calculating
uptime until the system operation is restored to the established
parameters and it is meeting the definition of operational mode.
    The EPA also agrees with the commenter that some facilities may
complete the testing needed to establish measured average DRE values in
the first or second year of each three year period, and would not be
required to perform any additional DRE testing until the start of the
next three-year period. The final rule has been revised since proposal
to allow a facility to postpone retesting of the affected unit with low
DRE until the next required testing period, instead of the next
reporting year.
    Comment: One commenter (an industry organization) stated that it
and its member companies have worked at considerable expense to
generate an extensive DRE test database, in support of this rule, so
that accurate default DREs could be incorporated into the rule. The
commenter noted that the additional data they collected increased the
number of fabs contributing data and the representativeness of the data
across the installed base of systems inventoried, compared to the data
available to develop the default DREs that were in the proposed
amendments.
    The commenter provided a summary of the member companies' abatement
system inventory and the number of individual abatement devices that
have been tested in support of the alternative default DRE calculations
proposed by the commenter. The commenter contended that the EPA should
not utilize any data from devices that were not designed to abate F-GHG
or N2O in the EPA assessment of abatement device performance
and the determination of default DREs for the final rule.
    The commenter further explained that the testing represented a
substantial fraction of the installed base of devices at the companies
responding to a 2011 survey of industry association member companies.
The survey referenced by the commenter included results from five
companies representing nine facilities and approximately 50 percent of
the estimated number of abatement systems in U.S. fabs, based on a 2010
ISMI survey.\4\ The commenter noted that although the testing is
predominantly of one manufacturer's devices (i.e., greater than 95
percent of DRE measurements), this is representative because the U.S.
industry's installed base is predominantly that same manufacturer's
devices. The commenter explained that in a statistical sense, the
sample of devices tested exceeds the usual 10 percent threshold at
which a sample is deemed ``large'' and brings into play the ``finite
sample correction'' for variance, meaning that the sample is more than
a statistical representation and has begun to enumerate the population.
---------------------------------------------------------------------------

    \4\ The survey results were reported on page 2 of EPA-HQ-OAR-
2011-0028-0045, SIA Briefing Paper on abatement Issues: Destruction
Removal Efficiency (DRE), January 10, 2012. Submitted as part of
settlement documents for SIA v. EPA (D.C. cir. No. 1024).
---------------------------------------------------------------------------

    The commenter stated that the revised default DREs in the proposed
rule were based primarily on the results of testing carried out by SIA
members and their contractors. The information was provided to the EPA
and used to develop the revised defaults in the proposed rule
amendments. The commenter noted that since that initial submittal, SIA
members have carried out additional testing and collected additional
test results. The supplemental data reflect an additional 208 tests of
POU abatement device performance, including 143 new tests of etch gas
abatement and 65 new tests of NF3 abatement in chamber
cleaning. The complete data set with the initial data and the
additional data represents three companies and nine different fabs,
similar to the previously submitted data. The commenter provided the
additional data, as well as a detailed analysis, as attachments to
their comment letter, which are available in the docket (docket item
EPA-HQ-OAR-2011-0028-0095).
    The commenter also noted that they were not able to use the EPA
data collection template for new DRE test results because much of the
data gathering had either been completed or was underway before the
template was provided in the docket to the proposed rule. The commenter
stated that they had already begun using an alternative template based
on the data template SIA

used to provide data to the EPA previously. The commenter provided the
DRE data in an attachment to their comment letter and claimed that the
information in the attachment was sufficient to assess the
applicability and usefulness of the data while avoiding the
confidentiality issues inherent in the template the EPA provided.
    Response: The EPA thanks the commenter for the additional DRE data
and appreciates the effort expended to generate the DRE test database.
We acknowledge the similarities between the EPA data request sheet and
the SIA template and have accepted the data provided as meeting the
EPA's information needs. We have evaluated the additional data provided
and have incorporated the data into the existing abatement device
inventory to develop the default DRE factors in Table I-16 of the final
rule. The default DRE factors in the final rule are based on an
analysis of the average DREs from 343 performance tests, including 11
data points from the EPA's DRE dataset from the Technical Support
Document for Process Emissions from Electronics Manufacture (Revised
November 2010), 125 tests provided to the EPA from SIA after the
finalization of the December 2010 subpart I rule, and the 207 tests
provided to the EPA by SIA during the public comment period for this
rulemaking.
    EPA agrees with the commenter that data collected from abatement
devices that are not designed to abate F-GHGs should not be included in
the DRE testing database, and the EPA has not considered these data in
the development of the default DREs in the final rule. The EPA agrees
with the commenter that it is inappropriate to include devices that
only incidentally abate F-GHGs and N2O in the calculation of
default DREs, as these devices are unlikely to have the same emissions
reductions as systems specifically designed to abate F-GHGs. For the
same reason, we have revised 40 CFR 98.94(f)(3) such that facilities
may take credit for abatement using the default DREs only if they can
certify that the abatement systems were specifically designed to abate
F-GHGs or N2O and have a site maintenance plan that includes
the manufacturer's recommendations and specifications for installation,
operation, and maintenance for each abatement system. However, the
final rule also allows facilities to use measured site-specific DREs to
account for emission reductions from systems that were not specifically
designed to abate F-GHGs or N2O.
    The EPA remains interested in obtaining more information about
whether the abatement system data are fully representative of the
abatement system technologies currently installed in the U.S. industry.
As discussed in the next response to comment, the EPA generally agrees
with the commenter's conclusion that the data provided are
representative of the facilities required to report under subpart I.
The EPA intends to collect and review additional data to improve the
DRE database in the future. The EPA's analysis of the DRE data provided
by the commenter and the method used to calculate the default DREs in
the final rule are discussed in the response to the next comment.
    Comment: Several commenters disagreed with the EPA's method for
calculating the default DRE factors that were included in the proposed
rule. The EPA calculated the proposed default DRE factors as the
arithmetic mean DRE value for a gas and process combination, minus two
standard deviations of the population.\5\
---------------------------------------------------------------------------

    \5\ p. 3 of Technical Support for Accounting for Destruction or
Removal Efficiency for Electronics Manufacturing Facilities under
Subpart I, EPA-HQ-OAR-2011-0028-0082.
---------------------------------------------------------------------------

    Several commenters proposed an alternative method for calculating
default DRE factors. The commenters claimed that the suggested approach
is conservative, mirrors the approach SIA used in the facility level
error analysis for emissions factors (see docket item EPA-HQ-OAR-2011-
0028-0074, section 3.4.1), and recognizes that the number of individual
devices in a typical fab is an important determinant of variability.
The commenter provided data from an industry association survey on the
number of abatement systems used at each fab for each gas and process
type. The commenter's approach attempted to estimate the lowest average
DRE value that any fab could be expected to achieve (``lowest fab-
average''). Specifically, it placed the default DRE at the bottom of
the distribution of fab averages, by discounting two standard
deviations below the observed fab-average DRE. It is important to note
the standard deviation used by the commenter is one that described the
combined variation of fab-averages and the variation of devices, unlike
the EPA method that used only the standard deviation of individual
device performance (i.e., the population of all devices).
    The commenters stated that fab-level averages should be the basis
of emissions reporting because no fab has just one POU device, and
site-specific DREs developed under the rule would be applied as fab-
averages. They stated that discounting the default to the lowest
expected fab-average would still fully protect against the risk of
under-estimating emissions in reporting due to a default DRE that is
too high. The commenters suggested that the majority of fabs would have
a higher average and would still have an incentive and mechanism to
obtain site-specific DREs.
    The commenters asserted that their approach uses a well-accepted
statistical methodology called Components of Variance Analysis to model
the variance in the DRE data and separately identify the variation in
the average DRE among fabs versus the variation in DRE among individual
devices in a fab. The variance components method applies a random
effects model to the data for the purpose of identifying the sources of
variance in a sample and making inferences regarding the size
(magnitude) of each source of variance. A random effects model is used
because it is unknown in advance whether a particular fab or device is
above or below the average for fabs or for devices within the fab. The
commenter provided references for background information on the
components of variance analysis.
    The commenter provided a detailed description of their approach and
a summary of default DREs calculated using their approach and compared
to the EPA's proposed default values.\6\ The commenter contended that
for each gas and process combination, the alternative defaults were
conservative representations of the average performance of abatement
devices in the test data because, by design, they targeted the fab with
the lowest average DRE.
---------------------------------------------------------------------------

    \6\ See EPA-HQ-OAR-2011-0028-0095.
---------------------------------------------------------------------------

    The commenter urged the EPA to reconsider its method for
discounting the available data to develop default DRE values. The
commenter recommended that the EPA adopt their procedure documented in
their comment letter and establish revised default DREs comparable to
their developed alternative DREs for the following reasons:
    (1) The EPA method of default DRE calculation in the proposed rule
was overly conservative because it discounted for the entire
variability of individual device performance that resulted from the
varied operating conditions existing in a semiconductor manufacturing
fab. The commenter claimed their method is designed to discount to a
similar degree, but only for the variability that exists in fab-average
DREs.
    (2) In determining the average DRE for a fab, the individual device
variability is attenuated by the large number of

abatement devices in service in each fab. As with the variability in
the emissions factors, considering the large number of individual
devices in an abated fab brings the overall fab average DRE much closer
to the overall average of the entire database.
    (3) For all of the gas/process type combinations, the alternative
default DREs developed using the commenters' recommended approach are
less than the average DREs observed in the majority of the fabs that
provided testing, demonstrating sufficient conservatism to prevent an
under-estimation of emissions when the alternative default DREs are
used in reporting. While they are higher than the default DREs in the
proposed rule, the commenters stated they are designed to represent the
fab with the lowest average DRE. They stated that very few fabs would
have lower average DREs and, due to the expense of testing, fabs would
not obtain site-specific DREs in all cases where their actual DREs are
higher. The commenter asserted that by using their default DREs,
reported GHG emissions would not be understated.
    Response: The EPA agrees with the commenters' proposed ``Components
of Variance Analysis'' averaging method for developing the default DREs
in Table I-16 of the proposed rule. The EPA acknowledges that the
averaging method used in the proposed rule may result in a lower
default DRE than may be present at fabs using many individual abatement
devices. This approach was used in the development of the proposed rule
based on the limitations in the information available at the time of
the proposed rulemaking. About 95 percent of the data available for the
proposed DRE values came from systems from a single manufacturer, and
the EPA was concerned that the data might not be representative of the
performance of other device manufacturers. However, for the 2011 data
reporting year, 50 facilities reported GHG emissions to the EPA under
subpart I. Of those 50 facilities, 17 reported having abatements
systems and the vast majority of those 17 reported abatement systems
from the same manufacturer. Only four facilities with abatement systems
had no systems from the manufacturer that represented greater than 95
percent of the DRE test data points. Therefore, the EPA generally
agrees with the commenter's conclusion that the data provided are
representative of the facilities required to report under subpart I
that have abatement systems. In addition, as noted in comments earlier
in this section, the EPA received additional data during the public
comment period that was incorporated into the DRE database. The
expanded data provide average DREs from 343 performance tests. This
more robust dataset provides greater confidence for the establishment
of default DREs for specific gas and process types/subtypes.
    The EPA agrees that the approach recommended by the commenters is a
valid statistical method that will account for the variance in the
average DRE from each fab in addition to the variance in the average
DRE from individual devices in each fab. The EPA also agrees with the
commenter that this approach is more appropriate for the final rule
than the approach used at proposal because the survey data provided by
the commenter and the results of the 2011 GHGRP reporting year have
demonstrated that the large majority of abatement systems in use are
from the same manufacturer for which the majority of the data were
collected. Therefore, the EPA's concerns with the representativeness of
the DRE data documented at proposal have been largely addressed by the
data received in the public comments and by the results of the 2011
annual GHG reports. The EPA remains interested in working with industry
stakeholders to develop a more robust DRE dataset that includes all
abatement system manufacturers.
    The approach recommended by commenters takes the average minus two
times the standard deviation of the average observed DRE (See Docket
Id. No. EPA-HQ-OAR-2011-0028-0095). The standard deviation used is one
that describes the variation of fab-averages. The method first
discounts the observed average for the standard deviation among fabs,
and places the default at the bottom of the statistical distribution
for the lowest fab-average, then accounts for the effect of individual
device performance. As noted by the commenter, using the recommended
approach, the calculated DREs represent the fab with the lowest average
DRE, which still results in a conservative estimate. The EPA agrees
that this approach is appropriate and has adopted the method to
determine the default DREs for each gas and process type/subtype in the
final rule. In cases where no new data were received (e.g., for
N2O using processes and other F-GHGs not listed), we have
retained the default DRE in the current subpart I of 60 percent, as
described in Table 3 to the preamble to the proposed amendments (see 77
FR 63563). The following table shows the sample size, mean, standard
deviation, and the calculated default DRE for each gas and process type
using the final expanded dataset.

                 Table 3--Summary of Calculated Default DRE Where Additional Data Were Provided
----------------------------------------------------------------------------------------------------------------
                                                                        Standard deviations       Calculated DRE
                                  Number of data                 --------------------------------      (using
        Gas/process type              points           Mean                                       components  of
                                     available                         Fabs           Devices        variance
                                                                                analysis)
----------------------------------------------------------------------------------------------------------------
                                                                       Etch
                                 -------------------------------------------------------------------------------
CF4.............................              66           83.56            0.0            18.31            75.4
CH3F............................               4           99.24            0.0             0.93            98.4
CHF3............................              43           99.10            0.69            1.14            97.4
CH2F2...........................              30           98.74            0.62            1.59            96.8
C2F6............................               5           98.84            1.85            0.50            95.1
C4F6............................               9           98.55            0.0             2.54            96.3
C4F8............................              24           98.50            0.75            1.69            96.4
C5F8............................               1           96.59          n/a             n/a               96.6
SF6.............................              20           98.69            0.66            1.01            97.2
NF3.............................              31           98.51            0.0             4.20            96.3
                                 -------------------------------------------------------------------------------
                                                                   Chamber Clean
----------------------------------------------------------------------------------------------------------------

NF3 (All sub-types combined)....             110           93.32            1.83            9.38            87.8
----------------------------------------------------------------------------------------------------------------

    However, as described in the response to another comment in this
section of the preamble, the EPA is including in the final rule a
single combined default DRE value for all carbon-based F-GHG used in
the etch process, other than CF4, instead of individual DRE
values.
    The EPA also notes that the final rule provides provisions for
gathering additional DRE performance data in future years for updating
and revising the default DREs (see 40 CFR 98.96(y)). The EPA would
consider additional data that is representative of other abatement
system designs and manufacturers for update of the default DREs, when
those data become available.
    The final rule also provides for facilities who do not wish to use
the default DREs for reporting purposes by including the option to
perform site-specific DRE testing. We have revised the final rule to
clarify that facilities have the option to develop site specific DREs
for specific gas and process combinations on a fab-basis, while also
using default DREs for other gas and process combinations. These final
rule options allow flexibility and reduce burden for facilities who
wish to reflect the emission reductions from abatement systems for
reporting purposes.
    Comment: One commenter asked that EPA revisit the conclusion that a
lack of DRE data for C3F8 and
C5F8 requires that they be subject to default DRE
factors of 60 percent. The current data set includes one DRE value for
C5F8 and no DRE values for
C3F8. The commenter noted that the chemistry of
C3F8 is very similar to
C2F6 because both are fully fluorinated
molecules, although C3F8 will be more amenable to
abatement because of weaker molecular bonds associated with its
additional carbon atom when compared to C2F6.
Because of the similarity, the commenter stated the
C2F6 DRE data should be recognized as applicable
to C3F8.
    The commenter made a similar argument for
C5F8, and compared it to
C4F8 with an average DRE of 98.5 percent, and
also noted the one DRE measurement for C5F8 of
96.6 percent.
    Response: The EPA agrees with the commenter that for these two
compounds, the availability of DRE data for similar compounds justifies
the use of a higher default DRE than the 60 percent included in the
current rule and in the proposed amendments. The
C3F8 and C5F8 compounds are
more amenable to combustion than the C2F6 and
C4F8, respectively, because of the presence of
the additional carbon atom in the case of C3F8,
and the presence of an additional carbon and the C=C double bond in the
case of C5F8. Therefore, the same default DREs
for C2F6 and C4F8 can be
applied to C3F8 and C5F8,
respectively (See Table 4 of this preamble).
    Comment: One commenter asked that the EPA consider a single shared
DRE value for the carbon-based etch gases (besides CF4) to
simplify calculations. The commenter noted that based on the
commenter's method of calculating the default DREs, a single default of
97 percent would be appropriate. The commenter noted that in the
proposed amendments, the EPA proposed a single default of 98 percent in
proposed Table I-16 of subpart I for the gases for which the EPA had
DRE data (CHF3, CH2F2,
C4F8, and C4F6).
    Response: In the proposed rule, the EPA included NF3 and
SF6 among the etch gases CHF3,
CH2F2, C4F8, and
C4F6 and assigned a DRE of 98 percent due to
similarities in the calculated DREs for each gas. As discussed in this
section, the EPA has incorporated the additional DRE data submitted
during the public comment period into the existing dataset to calculate
default DREs for the individual compounds. The EPA recognizes that the
calculated DREs for the carbon-based etch gases (other than
CF4) are grouped in the range of 95 to 98 percent, using the
most recent data and methodology discussed earlier in this section. The
EPA agrees with the commenter that it would simplify calculations to
group together the carbon-based etch gases (other than CF4)
and assign a single default DRE to theses etch gases.
    For the combined carbon-based etch gases, the default DRE for
combined gases is calculated similarly to the default DRE for
individual gases, with the exception that a fixed number of DRE counts,
fab counts, and abatement systems per fab are assumed for each gas so
that the variance components for fabs and devices are the same for each
gas. This approach is used in lieu of the raw DRE average for each gas
(and the associated number of data DRE values, fabs, and abatement
systems) because the raw averages for each gas include variations
between fabs, and are therefore less precise. For example, even if a
high raw average is observed for an individual gas, this may be caused
by the fact that a disproportionate number of the observations are
coming from a fab which has ``above average'' DRE.
    The EPA calculated the variance components ([sigma](Fabs) and
[sigma](Devices)) for the carbon-based etch gases using statistical
software. The results are shown in Table 4 below. The variance
components only describe the variability between fabs and between
devices (any difference between gases is already accounted for by the
gas effect, which is assumed to be fixed). Therefore, these values do
not change for each gas. The default DREs are averaged over all the
carbon-based etch gases (other than CF4) to produce a group-
average DRE of 96.7 percent, which the EPA has rounded to a value of 97
percent in Table I-16 in the final rule. This default value will also
apply to C3F8 and C5F8, as
discussed in the response to the previous comment, even though there
were no DRE data for C3F8 and only one DRE data
point for C5F8.

                                                Table 4--Combined Etch DRE for Non-CF4 Carbon-Based F-GHG
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            DRE fixed                                                                                Group-
                Input gas                     effect     DRE count       Fabs     [sigma](Fabs)  [sigma](Devices)       N       Default DRE  average DRE
--------------------------------------------------------------------------------------------------------------------------------------------------------
C2F6.....................................         98.6          116            5         0.631             1.523             5        96.76  ...........
C4F6.....................................         98.6          116            5         0.631             1.523             5        96.74  ...........
C4F8.....................................         98.7          116            5         0.631             1.523             5        96.80  ...........
C5F8.....................................         96.8          116            5         0.631             1.523             5        94.97        96.71
CH2F2....................................         98.9          116            5         0.631             1.523             5        97.00  ...........
CH3F.....................................         99.2          116            5         0.631             1.523             5        97.33  ...........
CHF3.....................................         99.2          116            5         0.631             1.523             5        97.35  ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Comment: Several commenters expressed concern regarding the
certification requirements for abatement systems under proposed 40 CFR
98.94(f) and 40 CFR 98.96(q).
    In regards to the requirement that reporters who wish to account
for abatement must certify and document/verify that the abatement
devices were installed, operated, and maintained in accordance with
manufacturer recommendations and specifications, one commenter stated
that manufacturer's specifications may no longer be available. The
comment explained that even when they are available, the specifications
can be general and do not specifically call out how to manage and
maintain the abatement devices. Typically, this requires the fab to
create a site-specific maintenance plan, which will be based on a
combination of available manufacturer's updated specifications and/or
the fab-specific procedures developed through subsequent operating and
maintenance experience. Material changes to the manufacturer's
specification requirements for their abatement systems may be necessary
to address process or equipment specific requirements in an operating
fab.
    The commenter noted that for existing older abatement systems, it
is not always possible to determine that they were installed in
accordance with manufacturer specifications at the time of their
original installation, which in many cases preceded this rule. Records
of the manufacturer's intent and installation requirements may not have
existed and, if they did exist, they were not kept. Importantly,
process tool(s) and gases/liquid precursors may have changed since the
initial installation. It is critical that abatement systems be operated
and maintained properly in the periods when emissions are being
reported and that the current infrastructure and system configuration
are appropriate for the abatement application. It is not germane
whether the abatement systems were installed in a particular way in the
past, as some of the systems at specific fabs have been in operation
for up to a decade.
    The commenter further explained that some process types may require
parameters outside of the manufacturer's specification requirements to
address complications introduced by specific material types, reaction
products, or to meet specific safety requirements. ``Tuning'' of
operating parameters and/or maintenance schedules different from the
abatement system manufacturer's recommendations are required to
optimize system operation in these cases. The commenter noted that
examples of maintenance plan adjustments beyond the original
manufacturer's recommendations to maximize the DRE for CF4
abatement were discussed in docket EPA-HQ-OAR-2011-0028-0046 item
4a.\7\
---------------------------------------------------------------------------

    \7\ Questions Generated from SIA/EPA Conference Calls and
Outstanding Questions from Work Plan appendices, March 29, 2012.
---------------------------------------------------------------------------

    The commenter contended that the purpose of the site maintenance
plan is to ensure that the abatement devices are operated and
maintained correctly. The commenter stated that the plan should be a
dynamic document that incorporates improvements in how the abatement
devices are serviced and maintained, including corrective actions that
are taken when the causes of abatement system failure or outage are
determined. In addition, proper set-up of abatement device in GHG
abatement mode after maintenance will be addressed. The commenter
reasoned that, by their nature, these plans may depart from the
original manufacturer's specifications.
    Response: The EPA agrees with the commenter that there are
scenarios in which a facility may not be able to rely on manufacturer's
specifications (e.g., if they are unavailable), or where the facility
may have a need to adopt fab-specific procedures to optimize system
performance. As such, we have revised 40 CFR 98.94(f)(1) and 40 CFR
98.96(q) to specify that facilities must certify and document that the
abatement systems are properly installed, operated, and maintained
according to the site maintenance plan for abatement systems that is
developed and maintained in records as specified in 40 CFR 98.97(d).
    However, the EPA also recognizes that manufacturers specifications
are still important to ensuring the proper installation and operation
of abatement systems and the reference to manufacturers specifications
has been retained in 40 CFR 98.97(d)(9). As noted in docket item EPA-
HQ-OAR-2011-0028-0046, item 4, cited by the commenter and incorporated
into the ``Technical Support for Accounting for Destruction or Removal
Efficiency for Electronics Manufacturing Facilities under Subpart I''
(see Docket ID. No. EPA-HQ-OAR-2011-0028-0082), during the review of
DRE test data for the revision of the default DRE, the EPA and SIA
noted that some low CF4 and NF3 DREs in the test
data resulted from variation in flows through the abatement system and
from operating and maintaining the abatement systems outside of the
manufacturer specifications. Specifically, low CF4 DREs
associated with etch processes were found to be the result of systems
operating outside the manufacturers' recommended set points for flow
rate and/or pressure that should have been verified during abatement
installation. The document cited by the commenter reported that once
the abatement systems were returned to the manufacturer's
specifications, the DRE also returned to higher levels comparable to
those of other systems. Because the high variability in the available
DRE data was directly associated with operating outside of the
manufacturer's specifications, the EPA proposed a requirement for
facilities to develop, follow, and keep on-site maintenance plans for
abatement systems that are built on the manufacturer's recommended
installation, operation, and maintenance program, and that must include
a defined preventive maintenance process and checklist and a corrective
action

process to follow whenever an abatement system fails to operate
properly.
    Therefore, the EPA has determined that although a certification may
rely on the implementation of site maintenance plans for abatement
systems, it is also necessary to ensure that facilities rely on
manufacturer's recommendations and specifications to the extent
possible, particularly when using the default DRE values. Therefore, if
the facility uses the emissions estimation methods in 40 CFR 98.93(a),
(b), and (i) and uses the default DRE values when claiming abatement
for reporting purposes, the final site maintenance plan requirements in
40 CFR 98.97(d)(9) for abatement systems must be based on the
manufacturer's recommendations and specifications for installation,
operation, and maintenance. If the facility is using properly measured
site-specific DRE values, the final site maintenance plan must include
the manufacturer's recommendations and specifications for installation,
operation, and maintenance, where available. For a facility to use the
default DREs, the EPA needs assurance that the abatement system is
installed, operated, and maintained in accordance with the
manufacturer's specifications. Otherwise, the EPA would be unable to
verify that the default DREs are met without further validation
testing. The site maintenance plan for abatement systems must also
include documentation where the operation and maintenance deviates from
the manufacturer's specifications, including an explanation of how the
deviations do not negatively affect the performance or destruction or
removal efficiency of the abatement system. For example, the site
maintenance plan may include documentation where the process optimizes
system performance (e.g., more frequent maintenance checks or tighter
operating parameters). Finally, facilities who elect to claim abatement
for reporting purposes and want to use the default DRE factors must
also certify that the abatement systems are specifically designed for
F-GHG abatement (or N2O abatement, as appropriate). (This
certification is not needed for facilities using a measured site-
specific DRE value.) The facility must also have a site maintenance
plan that is based on the manufacturer's recommendations and
specifications for each abatement system These are minimal requirements
that are necessary to verify that abatement systems are operating
consistently at or above the default DRE. We note that the commenter
provided several additional recommendations for changes to the proposed
provisions for certifications regarding abatement systems and the use
of default and site-specific DRE values. Those comments and our
responses can be found in ``Reporting of Greenhouse Gases--Revisions to
the Electronics Manufacturing Category of the Greenhouse Gas Reporting
Rule: EPA's Response to Public Comment'' (see EPA-HQ-OAR-2011-0028).
    Comment: One commenter stated that the proposed rule requires a
facility using the stack testing alternative to make assumptions for
abatement system DREs in order to adjust annual emissions calculations
for abatement downtime and does not allow one to assume a DRE of zero,
as would be an option under the emission factor method. The commenter
stated that this is a logical approach for a stack test method;
however, other portions of the rule require that a DRE assumption of
zero be used if a facility cannot meet certain requirements for
certifying the design and installation of an abatement device. The
commenter concluded that the net result is that, as the rule was
proposed, a facility that is unable to meet these certification
requirements (for example, one with older abatement equipment where
such certification may be difficult to obtain) is effectively
disqualified from using the stack test method as they may not assume
zero efficiency, yet cannot meet the requirements to assume something
other than zero. The commenter recommended revising the DRE
certification requirements such that the use of default DRE factors is
dependent upon certifying and documenting that the systems are
installed, operated, and maintained according to the site maintenance
plan, and not according to manufacturers specifications. The commenter
stated that this is consistent with the way in which other pollution
control devices are handled in many facility air permits.
    Response: In stack testing, the measured emissions used to
calculate fab-specific emission factors will reflect the effect of all
abatement systems, including those not specifically designed for F-GHG
abatement that still achieve some incidental F-GHG abatement. However,
the EPA recognizes that facilities using the stack testing method may
not be able to certify that the abatement systems are specifically
designed to abate F-GHGs, although those systems may achieve incidental
control of F-GHGs that could have an effect on emissions. As discussed
earlier in this section, we have revised the definition of ``abatement
system'' to clarify that the abatement system requirements of subpart I
only apply to abatement systems that are designed to abate F-GHGs (and/
or N2O, but N2O is not included in the stack
testing alternative), or for which the DRE has been measured according
to 40 CFR 98.94. Facilities using the stack testing alternative would,
in their emissions calculations, account for the effect of abatement
systems that are specifically designed for F-GHG abatement and for
systems for which the facility measured the site-specific DRE according
to 40 CFR 98.94. In the case of abatement systems that are not
specifically designed to abate F-GHG, the reporter may elect to not
include the effect of those systems in their emissions calculations. In
all cases where the reporter is accounting for the effect of the
abatement systems, the reporter must also comply with the other
monitoring and quality assurance requirements for abatement systems in
subpart I. In all other cases, the reporters would assume that the DRE
is zero for abatement systems that are not designed for abatement of F-
GHG and would not account for the downtime of those systems.
    In order to ensure that the abatement systems, as defined in 40 CFR
98.98 and included in the emission calculations, are operated properly
and consistently following the initial stack test, the EPA is requiring
that facilities must certify that the abatement system is operated and
maintained in accordance with the site maintenance plan for abatement
systems in 40 CFR 98.97(d). Facilities who elect to use the stack
testing alternative in 40 CFR 98.93(i) and who elect to use the default
DREs must base the site maintenance plan on the abatement system
manufacturer's recommendations and specifications. If manufacturer's
recommendations and specifications are unavailable, the facility using
the stack test method must use a site-specific DRE, which can be
developed concurrently. Facilities using the stack testing method and
the default DREs must also certify that the abatement systems are
designed to abate F-GHGs.
    Finally, the EPA also needs to ensure that facilities using the
stack test alternative account for the abatement systems that are
present when calculating their facility annual emissions. We have
revised the final rule to clarify that facilities using the stack test
alternative must certify that all abatement systems that are designed
to abate F-GHGs, or for which the DRE has been measured, are fully
accounted for when calculating annual emissions and accounting for
excess emissions from

downtime (i.e., facilities are accounting for the uptime and DREs of
these systems, either using the default DREs or site-specific DRES, in
Equations I-21 through I-24). Facilities would only apply the default
DREs to account for abatement from those systems that meet the
certification requirements and are specifically designed to abate F-
GHGs. They would use a site-specific DRE for systems for which the
facility had measured a site-specific DRE. If they elect to account for
abatement from systems that are not specifically designed to abate F-
GHGs, they would use a site-specific DRE for these systems. These
requirements are necessary to ensure that the calculated emission
factors are representative and accurately reflect abatement.
6. Abatement System Uptime for Facilities That Manufacture Electronics
    Comment: One commenter proposed revisions to the definition of
uptime such that uptime is defined as ``the ratio of the total time
during which the abatement system is in an operational mode and
operating in accordance with the site abatement system maintenance
plan, to the total time during which production process tool(s)
connected to that abatement system are normally in operation.''
    Response: The EPA is not revising the definition of ``uptime'' as
suggested by the commenter. The EPA previously defined ``operational
mode'' as ``the time in which an abatement system is properly
installed, maintained, and operated according to manufacturers'
specifications as required in 40 CFR 98.93(f)(1). This includes being
properly operated within the range of parameters as specified in the
operations manual provided by the system manufacturer.'' Consistent
with the changes to the abatement system certification requirements in
the final rule, the EPA has revised the definition of ``operational
mode'' to reflect that the abatement system is properly installed,
maintained, and operated according to the site maintenance plan for
abatement systems. Therefore, the revisions to the definition of
``uptime'' as requested by the commenter are not necessary, as an
abatement system in operational mode must be operated within the
parameters of the site maintenance plan.
7. Triennial Technology Report for Semiconductor Manufacturing
    Comment: Several commenters expressed concern with an option for
the triennial technology report on which the EPA requested comment,
specifically the option to require additional information beyond that
proposed in 40 CFR 98.96(y). The preamble to the proposed amendments
requested comment on requiring that the reports include an analysis of
the effect of the introduction of new processes on existing tools,
where a new process could be defined as one that used a markedly
different gas mixture than the mixture used by previous processes
applied to achieve the same end (i.e., etch the same film or feature),
or that included a change in the radio frequency (RF) power and gas
flow rate (see 77 FR 63566). Commenters stated that these suggested
requirements appear to resurrect the recipe testing requirements
established in the original subpart I regulation published in December
of 2010 and which were specifically called out as unworkable in SIA's
petition for reconsideration. One commenter stated that, as described
in the petition for reconsideration, the recipe testing requirements
created unacceptable intellectual property risk, potential national
security concerns, significant disruption of fab operations, and
unreasonable and excessive economic impact. The commenters cited as
examples the impacts (cost and business disruption) of process
emissions factor testing that were experienced during the additional
emissions factor testing work that was completed in support of the
default factors that are in Subpart I. The commenters reported that in
one fab, testing required two weeks of time and cost over $25,000 (not
including lost production and fab staff support time) just to measure
12 emissions factors for 5 tools. The ISMI technology transfer report
``2010 ISMI Analysis of the Impact of Final Mandatory Reporting Rule
Subpart I on U.S. Semiconductor Facilities'' issued January 31, 2011
provides additional description of the impact of recipe level testing.
    The commenter further explained that the cost to test all new and
revised process recipes is very large. On average, each large facility
introduces 40 new etch processes per year and changes 56 etch recipes
per year; for 29 large facilities the testing cost per year equates to
$17 million or $51 million for three years. This assumes $35,000 for
testing/week and six recipes tested/week, according to the commenter.
    The commenter noted that the cost for tool downtime for the testing
over the three years would be an additional $6.9 million. (This assumes
11 hours of downtime for an 8 hour test and 3 hours for tool
requalification; $1.5 million per/year for etch tool downtime.) Total
cost for testing of tools is on the order of $58 million.
    The commenter asserted that the cost of any testing of POU
abatement devices for DRE changes would be additional. Costs for large
leading-edge technology fabs would be significantly higher than the
industry average numbers by a factor of 10 or more.
    The commenter stated that in the economic impact assessment for the
proposed amendments (EPA-HQ-OAR-2011-0028-0081), the EPA does not
include the cost for preparing the triennial report, ``. . . given that
the EPA does not expect this requirement to significantly affect the
compliance costs either on a per facility or a national basis . . .''
The commenter estimated that preparing a triennial report, as proposed
in the preamble to the revised subpart I, would require the effort of
several full time employees. The commenter stated that their intent
with regards to preparing the triennial report and developing a company
or industry plan to perform testing to assess the impact of new
(meaning significantly different from existing) processes, equipment,
and technologies on default emissions factors and default DRES, is to
enable the industry to pool its resources to most efficiently measure,
collect, and report the data needed to assess these changes. The
commenter further added that the adoption and propagation of distinctly
new processes, equipment, and technologies into high-volume
manufacturing occurs slowly, allowing a reasoned, considered plan to be
developed to assess the impact. Additionally, the commenter claimed
that their statistical assessment of the emissions factor data for
current manufacturing processes and equipment indicate that the
magnitude of the emissions factor is primarily dependent on the wafer
size and the gas type, suggesting that significant changes are unlikely
to occur frequently because these two variables are not changed
frequently.
    The commenter concluded that the level of information requested and
the cost associated with measuring and collecting data according to the
expanded scope of triennial reporting requirements described in the
preamble are excessive and the final rule should not include more than
what is included in the proposed 40 CFR 98.96(y).
    Response: Except for a minor technical correction, EPA is
finalizing the requirements for the triennial technology report as
proposed at 40 CFR 98.96(y). Facilities are not required to implement
recipe-specific testing in the first phase of the triennial technology
review, as some commenters inferred from the request for comment in the
preamble to the proposed amendments.

Nevertheless, EPA encourages, but does not require, facilities to
acquire measurements of gas utilization rates, by-product formation
rates, and DREs that reflect the impact of technology changes for the
triennial report, because such measurements would be useful for
informing future changes to the rule.
    To the extent that facilities acquire these measurements, either
because they perform the measurements themselves or because they
receive them from tool manufacturers, 40 CFR 98.96(y)(2)(iv) requires
facilities to submit them as part of the triennial report. That
provision states facilities must ``provide any utilization and by-
product formation rates and/or destruction or removal efficiency data
that have been collected in the previous 3 years that support the
changes in semiconductor manufacturing processes described in the
report.'' This requirement refers to all the rate or DRE measurements
collected in the previous 3 years that reflect the impact of any
technology changes during that time. Submission of specific selections
or subsets of those measurements would not meet this requirement
because such selections or subsets may not be representative. We
anticipate that the types of information submitted would include
information similar to that submitted to inform the default emission
factors and default DREs in today's rule.
    In the proposal, we also requested comment on whether triennial
reports should include gas utilization rates and by-product formation
rates measured ``for all new tools acquired by the facility over the
previous 3 years as well as gas utilization rates and by-product
formation rates measured for new processes run on existing tools'' (77
FR 63566). For these measurements, testing data for new tool models is
often available from the manufacturer or from performance tests as new
tool models are installed. The EPA anticipates that this information
could be used to inform future changes to the rule and could be
supplied through the triennial report. While the EPA is not requiring
that this information be included in the triennial report, the agency
encourages reporters to include this information on a voluntary basis
where practical.
    The final rule does not require the triennial report to consider
process or technology changes at the recipe-specific level, nor does it
require facilities to collect any recipe-specific data. However, the
report should address whether, over time, the facility has
incrementally implemented process or technology changes that have now
cumulatively resulted in a wide-spread effect on emission factors or
DRE factors. The report would not need to consider each incremental
change separately. For example, the report does not need to consider
differences in flow rates among individual recipes and their effect on
the emission rates of individual gases. However, if the industry
implements or adopts a technology change that substantially affects the
average flow rate for a given process type such that the current
default emission factors may no longer be representative, the cause and
potential impact of that change in flow rate should be addressed in the
triennial technology review report (though not detailed at the recipe-
level). See Section II.A.12 of this preamble for additional discussion
of the contents of the triennial report. The EPA agrees with the
commenter that the triennial technology review should avoid the burden
and potential disclosure concern associated with the provisions for
reporting of recipe-specific information that appear in the December
2010 promulgated rule and that are removed from this amended rule.
    We note that commenters provided additional input regarding the
triennial technology report. Those comments and our responses can be
found in ``Reporting of Greenhouse Gases--Technical Revisions to the
Electronics Manufacturing Category of the Greenhouse Gas Reporting
Rule: EPA's Response to Public Comment'' (see EPA-HQ-OAR-2011-0028).
8. Final Amendments to Reporting and Recordkeeping
    Comment: One commenter noted that a facility may have multiple
fabs, which each process different wafer sizes. The commenter
recommended that the language in 40 CFR 98.96(a) and (b) apply to fabs
rather than facilities. The commenter noted that the wafer size and
capacity could then be reported for each fab, rather than trying to
report for the entire facility.
    Response: The EPA appreciates the input provided by the commenter
regarding facility and fab level reporting requirements. The EPA agrees
with the commenter that the language in 40 CFR 98.96(a) and (b) should
apply to fabs rather than facilities. As a result, the EPA is
promulgating the final amendments to subpart I with the proposed
modifications to 40 CFR 98.96(a) and (b).
    Comment: One commenter asserted that the facility-wide DRE
reporting requirement under 40 CFR 98.96(r) using Equations I-26, I-27,
and I-28, should not apply to the stack test alternative. The commenter
noted that the derivation of a facility-wide DRE is unnecessarily
complicated, subject to error, and provides no material benefit to the
reporting of emissions under the stack test option. According to the
commenter, the EPA's proposed requirement to use these equations
entails an artificial determination of how much of a facility's
emissions are coming from the process tools versus the abatement
systems, and as such is complicated, somewhat arbitrary, and
potentially subject to errors. The commenter stated that the
requirement to determine an effective, facility-wide or fab-wide DRE
using equations I-26 and I-28 for facilities that choose the stack
testing method (40 CFR 98.93(i)) is not logical and should be removed
from the rule.
    The commenter explained that one of the benefits of the stack
testing method is that it eliminates the need to test individual
abatement units, which is costly. The stack test data combines the
impact of the gas utilization factors in the equipment and the
abatement system DREs into a single emissions factor for the facility.
Whether a fab chooses to generate and use site-specific DREs or use the
default DRES, the DREs will only be used to adjust fab emissions for
abatement system downtime; adjustments which are expected to have a