[Federal Register Volume 80, Number 129 (Tuesday, July 7, 2015)]
[Rules and Regulations]
[Pages 38628-38652]
[FR Doc No: 2015-16385]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2013-0696; FRL-9929-25-OAR]
RIN 2060-AR81

Performance Specification 18--Performance Specifications and Test
Procedures for Hydrogen Chloride Continuous Emission Monitoring Systems
at Stationary Sources

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is finalizing
performance specifications and test procedures for hydrogen chloride
(HCl) continuous emission monitoring systems (CEMS) to provide sources
and regulatory agencies with criteria and test procedures for
evaluating the acceptability of HCl CEMS. The final performance
specification (Performance Specification 18) includes requirements for
initial acceptance, including instrument accuracy and stability
assessments. This action also finalizes quality assurance (QA)
procedures for HCl CEMS used for compliance determination at stationary
sources. The QA procedures (Procedure 6) specify the minimum QA
requirements necessary for the control and assessment of the quality of
CEMS data submitted to the EPA.
    This action establishes consistent requirements for ensuring and
assessing the quality of HCl data measured by CEMS. The affected
systems are those used for determining compliance with emission
standards for HCl on a continuous basis as specified in an applicable
permit or regulation. The affected industries and their North American
Industry Classification System (NAICS) codes are listed in the
SUPPLEMENTARY INFORMATION section of this preamble.

DATES: This final rule is effective on July 7, 2015.

ADDRESSES: Docket: The EPA has established a docket for this rulemaking
under Docket ID No. EPA-HQ-OAR-2013-0696. All documents in the docket
are listed on the www.regulations.gov Web site. Although listed in the
index, some information is not publicly available, e.g., Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Certain other material, such as copyrighted
material, is not placed on the Internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available either electronically through www.regulations.gov or in hard
copy at the EPA Docket Center, Room 3334, EPA WJC West Building, 1301
Constitution Ave. NW., Washington, DC 20004. The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the EPA Docket Center is
(202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Ms. Candace Sorrell, Office of Air
Quality Planning and Standards, Air Quality Assessment Division (AQAD),
Measurement Technology Group, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27709; telephone number: (919)
541-1064; fax number:<PHONE_NUMBER>; email address:
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: The information in this preamble is
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. Judicial Review
II. Background
III. Changes Included in the Final Performance Specification 18 and
Procedure 6
IV. Summary of Major Comments and Responses
    A. Dynamic Spiking
    B. Duplicate Trains When Performing RATA
    C. Stratification Test Requirements
    D. Calibration Range Above Span
    E. RATA Acceptance Criteria for Low Concentration Sources
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)

    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA)
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act (CRA)

I. General Information

A. Does this action apply to me?

    The major entities that would potentially be affected by the final
Performance Specification 18 (PS-18) and the QA requirements of
Procedure 6 for gaseous HCl CEMS are those entities that are required
to install a new HCl CEMS, relocate an existing HCl CEMS, or replace an
existing HCl CEMS under any applicable subpart of 40 CFR parts 60, 61,
or 63. Table 1 of this preamble lists the current federal rules by
subpart and the corresponding source categories to which the PS-18 and
Procedure 6 potentially would apply.

  Table 1--Source Categories That Would Potentially be Subject to PS-18
                             and Procedure 6
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              Subpart(s)                         Source category
------------------------------------------------------------------------
                             40 CFR part 63
------------------------------------------------------------------------
Subpart LLL...........................  Portland Cement Manufacturing
                                         Industry.
Subpart UUUUU.........................  Coal- and Oil-fired Electric
                                         Utility Steam Generating Units.
------------------------------------------------------------------------

    The requirements of PS-18 and Procedure 6 may also apply to
stationary sources located in a state, district, reservation, or
territory that adopts PS-18 or Procedure 6 in its implementation plan.
    We plan to amend 40 CFR part 63 subpart UUUUU, National Emission
Standards for Hazardous Air Pollutants: Coal- and Oil-fired Electric
Utility Steam Generating Units to offer PS-18 and Procedure 6 as an
alternative to Performance Specification 15 (PS-15) for continuous
monitoring of HCl. On February 17, 2015 (80 FR 8442), we proposed
amendments to appendix B of subpart UUUUU that clarify that PS-18 and
Procedure 6 will be allowed and how they are to be implemented under
subpart UUUUU. Note, prior to the time that these amendments are
finalized, the alternative test method approval process of 40 CFR
63.7(f) is available as a way for affected facilities to request
approval to use PS-18/Procedure 6 in lieu of PS-15.
    With regard to 40 CFR part 63, subpart LLL, which affects Portland
cement manufacturing facilities and includes HCl monitoring
requirements, no amendments will be needed as Subpart LLL already
allows for use of any promulgated performance specification for HCl
CEMS in 40 CFR part 60, appendix B.
    Table 2 lists the corresponding NAICS codes for the source
categories listed in Table 1 of this preamble.

            Table 2--NAICS for Potentially Regulated Entities
------------------------------------------------------------------------
                          Industry                           NAICS Codes
------------------------------------------------------------------------
Fossil Fuel-Fired Electric Utility Steam Generating Units..   \a\ 221112
                                                              \b\ 221122
                                                              \c\ 921150
Portland Cement Manufacturing Plants.......................       327310
------------------------------------------------------------------------
\a\ Industry in Indian Country.
\b\ Federal, state, local/tribal government owned.
\c\ Industry in Indian Country.

    Tables 1 and 2 are not intended to be exhaustive, but rather they
provide a guide for readers regarding entities potentially affected by
this action. If you have any questions regarding the potential
applicability of PS-18 and test procedures (Procedure 6) to a
particular entity, consult the person listed in the FOR FURTHER
INFORMATION CONTACT section.

B. Where can I get a copy of this document and other related
information?

    In addition to being available in the docket, an electronic copy of
this action is available on the Internet through the EPA's Technology
Transfer Network (TTN) Web site, a forum for information and technology
exchange in various areas of air quality management, measurement
standards and implementation, etc. Following publication in the Federal
Register, the EPA will post the Federal Register version of the
promulgation and key technical documents on the TTN Web site: http://www.epa.gov/ttn/emc/promulgated.html.

C. Judicial Review

    Under section 307(b)(1) of the Clean Air Act (CAA), judicial review
of this final rule is available only by filing a petition for review in
the U.S. Court of Appeals for the District of Columbia Circuit by
September 8, 2015. Under section 307(d)(7)(B) of the CAA, only an
objection to this final rule that was raised with reasonable
specificity during the period for public comment can be raised during
judicial review. Moreover, under section 307(b)(2) of the CAA, the
requirements established by this final rule may not be challenged
separately in any civil or criminal proceedings brought by the EPA to
enforce these requirements. Section 307(d)(7)(B) also provides a
mechanism for us to convene a proceeding for reconsideration, ``[i]f
the person raising an objection can demonstrate to the EPA that it was
impracticable to raise such objection within [the period for public
comment] or if the grounds for such objection arose after the period
for public comment (but within the time specified for judicial review)
and if such objection is of central relevance to the outcome of the
rule.'' Any person seeking to make such a demonstration to us should
submit a Petition for Reconsideration to the Office of the
Administrator, U.S. EPA, Room 3000, William Jefferson Clinton Building,
1200 Pennsylvania Ave. NW., Washington, DC 20460, with a copy to both
the person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT
section, and the Associate General Counsel for the Air and Radiation
Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200
Pennsylvania Ave. NW., Washington, DC 20460.

II. Background

    The EPA recently promulgated the Portland Cement Maximum Achievable
Control Technology (MACT) rule (75 FR 54970, September 9, 2010; 78 FR
10006, February 12, 2013) and the Mercury and Air Toxics Standards
(MATS) rule (77 FR 9303, February 16, 2012; 78 FR 24075, April 24,
2013). Both rules specify the use of extractive Fourier transform
infrared spectroscopy (FTIR) and PS-15 when affected facilities opt or
are required to continuously measure HCl emissions. To facilitate use
of alternative technologies to FTIR and to aid in measuring the low
levels of HCl specified in those rules, the EPA has developed and is
promulgating these new specifications and quality control (QC)
procedures (PS-18 and Procedure 6) for HCl CEMS as an alternative to
the use of PS-15.

    Multiple technologies are available for HCl emissions monitoring.
The goals of PS-18 and Procedure 6 are (1) to allow for the use of
different HCl CEMS sampling and analytical technologies as long as the
required performance criteria set out in the performance specification
(PS) are met; and (2) to establish consistent requirements for ensuring
and assessing the quality of data measured by a HCl CEMS.
    Performance Specification 18 and Procedure 6 were proposed on May
14, 2014 (79 FR 27690). The initial public comment period was extended
(from 30 to 60 days; ending July 13, 2014) in response to commenter
requests. We reviewed and considered comments on the proposed PS-18 and
Procedure 6 and have made several changes to the specifications and QA
procedures finalized with this action to address concerns and improve
the proposed performance specifications and procedures.
    Under section 553(d) of the Administrative Procedures Act (APA), 5
U.S.C. 553(d), the agency may make a rule immediately effective ``for
good cause found and published with the rule.'' For the reasons
discussed below, the EPA believes there is ``good cause'' to make this
amendment effective upon publication in the Federal Register. This rule
establishes a new measurement option, and not a new underlying
requirement. The sooner the new option is available, more flexibility
will be provided to regulated parties.

III. Changes Included in the Final Performance Specification 18 and
Procedure 6

    This rule finalizes PS-18 and Procedure 6, as proposed, except with
five revisions in response to public comments. First, we expanded the
options for using dynamic spiking (DS) with extractive systems and
clarified the spiking procedures for integrated path systems through
the use of ``method of standard additions'' in daily QC checks and as a
replacement for the quarterly relative accuracy audit (RAA). Next, we
eliminated the requirement for paired or duplicate trains when
performing relative accuracy test audits (RATAs) using Method 26A. This
change was based on data provided by stakeholders and the EPA's Office
of Research and Development, which showed that this reference method
(RM) generated data acceptable to allay concerns about the data quality
at concentrations near the compliance limit. In response to commenters
who claimed that stratification testing is overly burdensome and
unwarranted, we revised PS-18 to offer three RM traverse point options
that can be used without the need for stratification testing and added
clarifying language concerning the stratification testing procedures.
We removed calibration range above span requirements in both PS-18 and
Procedure 6 because we decided, after considering concerns raised by
commenters, that above span compliance requirements are best handled on
a rule-specific basis within individual subparts regulating differing
industries/categories. The procedures for assuring the quality of the
data when an applicable regulation requires measurements above span
were not removed. Lastly, we added flexibility to both PS-18 and
Procedure 6 in the relative accuracy criteria.

IV. Summary of Major Comments and Responses

    A comprehensive summary of the comments received on the proposed
PS-18 and procedures (Procedure 6) and our responses to those comments
can be found in the Summary of Public Comments and Responses
document,\1\ which is available in the docket for this action (see
Docket No. EPA-HQ-OAR-2013-0696). Some of the major comments received
on the PS and QA procedures and our responses to those comments are
summarized by subject in the following paragraphs.
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    \1\ U.S. Environmental Protection Agency. Response to Comments
on Proposed Rule: Performance Specification 18--Specifications and
Test Procedures for Gaseous HCl Continuous Emission Monitoring
Systems at Stationary Sources. Office of Air Quality Planning and
Standards (OAQPS), Air Quality Assessment Division (AQAD), Research
Triangle Park, NC; May 2015.
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A. Dynamic Spiking

    Under the proposed PS-18, we required DS into the CEMS using a
National Institute of Standards and Technology (NIST) traceable
standard to demonstrate initial performance at sources with emission
levels near the detection limit of the CEMS.
1. Expanded Use of Dynamic Spiking as an Optional QC Check
    Several comments received on the proposal recommended that the EPA
allow for optional use of DS procedures for all certification and QA
procedures as alternatives to using external calibration standards.
Commenters opined that a choice between performing DS or daily zero and
upscale checks should be available to the manufacturer and CEMS user
for all CEMS technologies, and that the regulation should not mandate
the use of either technique to exclude particular technologies.
    After consideration of comments, we have revised the final PS and
QA procedures to allow for optional use of DS procedures for the
following:
    (1) The upscale (mid-level) portion of the 7-day calibration drift
test,
    (2) The daily mid-level CD check, and
    (3) The quarterly data accuracy assessments.
    In addition, if the source meets the criteria of section 5.5 in
Procedure 6, we are allowing for a dynamic spiking audit (DSA) as a
replacement for the RATA once every 2 years.
    A DS procedure does not provide sufficient information to replace
the 7-day or daily zero CD check, the initial measurement error (ME)
test, or completely replace the relative accuracy (RA) comparison with
a RM. The 7-day and daily zero CD checks using exclusively zero gas
provide an absolute check of the instrument zero. Should hysteresis be
a concern, humidified zero gas may be used.
    After consideration, we decided that DS was not a suitable
replacement for the 7-day or daily zero CD check. We added an
additional procedure for use of a DS as an option for the 7-day and
daily mid-level CD checks to section 11.8 of PS-18 and section 4.1 of
Procedure 6 in the final rule. The acceptance criteria for use of a DS
as a mid-level CD check is the same as that for the classic CD check
procedure, 5 percent of span for a single spike; an
equation has been added to appendix A of PS-18 for calculating this
value. It is important to note that under the final rule, the 7-day and
daily upscale CD checks (whether done using the classic procedure and
pure calibration gases or done using a DS procedure) are limited to the
use of a mid-level gas. The reason for this limitation is to (1) ensure
that the upscale calibration is closer to the measured values, (2)
mitigate hysteresis effects, and (3) ensure that the CD values
determined using either the classic procedure or a DS procedure are on
a consistent basis.
    We have retained the requirement for use of pure calibration gases
as the only option for the ME test. We retained this requirement
because we want (at least) an initial direct assessment of the
linearity of the system; we do not believe that the nominal costs
associated with hysteresis or gas use are critical concerns for this
requirement for a one time test.
    Use of a DSA as an option for quarterly data accuracy assessment
was included in the proposal for Procedure 6; and section 5.2.3 of
Procedure 6 has been revised to include clarifying information on spike
levels, number of spikes, and audit calculations.

    The final rule requires yearly conduct of a RATA involving
comparison against a RM unless the optional criteria are met to reduce
this requirement to every other year. The RATA provides quantitative
assessment of the CEMS as well as confirmation of the continued
representativeness of the CEMS sampling location. The DS option
confirms the quantitative output of the CEMS comparison but lacks the
traversing necessary to evaluate representativeness of the CEMS
sampling point.
2. Removal of the Dynamic Spiking Requirement for Low Emission Sources
    We received several comments on the proposed specifications
requiring a DS verification test whenever the HCl measurements are less
than or equal to 20 percent of the applicable standard (in section
<IP_ADDRESS>) arguing that the provisions are unnecessary. One commenter
asserted that there is no purpose or precedent for requiring
alternative or additional QA testing, in addition to a RATA, because a
unit is operating well below the applicable standard or the RM
quantification limit and that having such a requirement does not
appreciably provide any more assurances that the HCl CEMS is operating
properly than demonstrated by meeting the RA requirements. One
commenter asserted that kilns with very low or no HCl emissions should
not be required to conduct extra tests and that DS procedures
equivalent to those used in PS-15 DS should be allowed as an
alternative to the RA test and not in addition to the RA test to
validate installed CEMS.
    Upon review of these comments, we have decided that requiring a DS,
merely because emissions are low, may present a disincentive to
maintaining low emissions without appreciably assuring better operation
of HCl CEMS. Therefore, we have revised PS-18 to remove this
requirement for low HCl emission sources.

B. Duplicate Trains When Performing RATA

    The proposed PS-18 required (1) paired or duplicate trains when
performing RATAs using Method 26A as the RM and (2) invalidation of
data pairs not meeting specified relative difference criteria (sections
<IP_ADDRESS> and <IP_ADDRESS>).
    Several commenters requested that the requirement for paired trains
be removed when Method 26A is used as the RM when conducting a RATA.
Commenters argued that dual trains will add unnecessary time, more
expense, and will complicate the testing process. These commenters
generally opined that the additional burdens associated with requiring
dual trains will not increase accuracy and will make it more unlikely
that facilities will choose to implement HCl CEMS.
    Commenters generally expressed that both Method 26 and 26A have
been widely used for a number of years to develop data both to set
standards and to show compliance, and that Method 26A is very durable,
well-designed, and provides accurate/high quality data. One commenter
acknowledged that variability is higher as measurements get closer to
the detection limit; however, the commenter asserted that this is true
for any analytical method, not just Method 26A. Another commenter noted
that Method 26A has a known negative bias below 20 ppmv (parts per
million by volume); however, this bias would show up in both trains (if
a dual train was used) and would not have any impact on determining
accuracy.
    One commenter reported that PS-12A is the only known PS that
requires the use of paired RM sampling trains (see PS-12A, section
8.4.2), and requires dual trains when using Method 29. The commenter
further reported that paired trains are recommended but not required in
PS-11 (see section 8.6(1)(i)). The commenter suggested that the EPA
adopt an alternative standard in which the EPA would recommend the use
of paired trains, but not require them, similar to the requirements of
PS-11.
    One commenter stated that random uncontrolled events can occur that
can affect the results of a RM test, and if such an event occurs during
a RATA, the sample may not meet the relative difference (RD)
performance criteria and would count as one of a maximum of three
exclusions/rejections allowed in the proposed PS-18. This commenter
contended that if dual trains are employed, there is twice the
probability of a random event occurring that could result in a
rejection. One commenter stated that requiring dual trains could result
in the discarding of otherwise valid RM runs.
    Commenters asserted that if the RM data is of poor quality or there
is a large enough error in the reference point, either that data point
will have to be discarded (if allowed) or the instrument will not pass
the RATA. One commenter opined that facilities should have the choice
to use single trains and risk failing the RATA due to suspect RM data.
    We acknowledge that requiring duplicate Method 26A trains during
RATA tests adds some complexity and cost to initial and ongoing quality
demonstration of CEMS performance. Our primary concern is the
confidence in RM data at low concentrations. We also acknowledge that
the PS-18 proposal only requires duplicate sampling for Method 26A and
does not address duplicate Method 320/Method 321 as a requirement
during RATA testing. Furthermore, from the data provided by
stakeholders and by the EPA's Office of Research and Development
(evaluating the use of paired Method 26A trains), we are convinced that
Method 26A performs as a prescriptive method to generate data
acceptable to allay concerns about the quality of this RM at
concentrations at the compliance limits of current MACT rules. We have
revised PS-18 to remove the requirement for paired reference Method 26A
sampling trains during RATA tests.

C. Stratification Test Requirements

    Several commenters opined that stratification testing is overly
burdensome and unwarranted.
    One commenter opined that the stratification test would be overly
burdensome for sources using Method 26A because test results would not
be readily available onsite, which would force sources to use
instrumental methods (e.g., Method 320) that yield real time HCl data.
Another commenter stated that the requirements for a stratification
test for HCl are unwarranted because extractive CEM or cross-stack
tunable diode laser (TDL) instruments are only effective in measuring
HCl in the vapor phase, and stratification only occurs with non-vapor
droplets and higher-mass aerosols. The commenter asserted that gas
phase measurements have always been associated with a homogeneous
mixture of molecules across a stack or duct under turbulent flow
conditions, which is always the case at plants with HCl emission
streams. The commenter asserted that other reasons why a stratification
test is not warranted include (1) the fact that other extractive HCl
RMs, including Methods 320, 321, and ASTM D6348-12, do not require a
stratification test, and (2) if stratification exists and is
statistically significant, the error would be revealed by the RA test.
    One commenter asserted that there may be units that would be
subject to PS-18 under subpart UUUUU and other rules (e.g., 40 CFR part
75) that have already performed stratification testing at their RM
sampling location. The commenter suggested that to avoid unnecessary
repetitive stratification testing, the EPA include an exemption from
the stratification testing

requirement for RM locations that have been previously evaluated.
    Another commenter stated that the proposed stratification test
procedures and acceptance criteria specified in section 11.9.3 of the
proposal (1) are unnecessary for most sources and do not need to be
performed, (2) contain confusing references to the CEMS and RM sampling
points, (3) provide inappropriate acceptance criteria, and (4) are not
supported by any data.
    One commenter suggested that the stratification test sections be
revised to (1) eliminate the test when the monitor and RA test
locations are downstream of induced draft (ID) fan or other well mixed
location, (2) eliminate the test for sources that have no measurable
HCl during mill on operation, (3) explicitly state stratification tests
should not be done during transient conditions including mill off
operation, (4) specify that only an oxygen (O2) traverse is
necessary if the only potential source of stratification is air in-
leakage, (5) specify a stratification test, when necessary, be done at
the RA test location and not the CEMS location, if different, and (6)
specify that level of detection (LOD) criteria for allowing the
alternative sulfur dioxide (SO2), carbon dioxide
(CO2), and carbon monoxide (CO) tests are based on the RM
LOD and not the CEMS LOD.
    One commenter also suggested that, unless the EPA can demonstrate
that HCl stratification is an actual issue, the EPA should revise PS-18
to incorporate the identical requirements in PS-2, section 8.13.2, that
requires sampling three points on a line, and require stratification
tests only where there is a reason to expect stratification actually
exists. The commenter also asserted that there is no need to acquire
and use a series of EPA Protocol SO2 calibration gases and
comprehensive series of procedures intended for test runs.
    We disagree with the commenters that stratification testing is
unnecessary and overly burdensome. Contrary to the assertions of some
commenters that stratification testing is not necessary, gaseous
pollutants can be stratified. While turbulent flow and other conditions
may eliminate stratification under certain conditions, the EPA does not
agree that those conditions can be easily defined nor that if
stratification exists, it would always be revealed by the RA test. It
is the EPA's position that to ensure collection of representative RM
samples, it is necessary to confirm the absence of stratification
before allowing single point or 3-point sampling that does not include
the centroid of the duct.
    However, we do recognize that there is a need to provide one or
more options for RM sample point selection that do not require
stratification testing and we also understand that the proposed
language of section 11.9.3 may have caused some confusion. Therefore,
we have revised PS-18 to offer three RM traverse point options that can
be used without the need for stratification testing. These options are
a 3-point traverse (commonly known as the a ``3-point long line'') that
includes the centroid of the duct, a 6-point traverse as allowed under
40 CFR part 75, or a 12-point traverse, as was requested by one
commenter. Testers desiring to test at a single point or at three
points within two meters of a single port (commonly known as a ``3-
point short line'') will need to conduct stratification testing to
demonstrate the absence of stratification or only minimal
stratification, respectively.
    Additionally, after consideration of comments received on
stratification testing, we have also revised the final PS-18 to:
    (1) Clarify that the purpose of stratification testing is only for
selection of RM sampling points;
    (2) Simplify the use of SO2 as a surrogate for
stratification testing without restriction to offer a simpler option
when using Method 26A as the RM;
    (3) Clarify (as commenters have recommended) that stratification
testing must be conducted at the same location as the RM testing; and
    (4) Clarify that stratification testing should not be conducted
during transient conditions.

D. Calibration Range Above Span

    Commenters expressed concern over the proposed requirements related
to calibration range above span or CRAS (defined as the upper limit of
the measurement range based on a conservatively high estimate of the
range of HCl measurements expected from the source category).
Specifically, commenters expressed concern that the proposed CRAS
requirements:
    (1) Conflict with the definition of ``span'' in both 40 CFR part
60, subpart UUUUU (subpart UUUUU), appendix A, and in 40 CFR part 75
(section 72.2).
    (2) Conflict with the recently promulgated 40 CFR part 63, subpart
LLL (subpart LLL) requirements.
    (3) Would likely create one hour of unnecessary CEMS data loss each
time it is performed in view of the time required for the CEMS to
achieve and stabilize at the high concentration level and subsequently
recover to the normal operating level.
    (4) Require that the HCl CEMS be adjusted when the calibration
drift exceeds 0.5 ppm (parts per million) at the zero or at 15-20 ppm
levels. Commenters stated that upscale or CRAS levels would impose
arbitrary adjustments simply chasing noise and that it should be
changed to a requirement to inspect the CEMS and determine the proper
corrective action.
    Commenters stated that the span and range of a CEMS depend on the
type of technology used and that the EPA references the mercury CEMS as
the precedent for the above span requirement. Commenters asserted that
this can be problematic because, whereas mercury CEMSs have a linear
response, other technologies may not have a linear response.
    After considering concerns raised by commenters, we decided that
above span calibration requirements are best handled on a rule-specific
basis within individual subparts regulating differing industries/
categories. Therefore, we revised PS-18 and Procedure 6 to remove
calibration range above span requirements and made them an option in
Procedure 6. Subpart LLL-specific above span calibration technical
revisions have been made under that rulemaking (see 79 FR 68821;
November 19, 2014).

E. RATA Acceptance Criteria for Low Concentration Sources

    The proposed PS-18 section 5.3.5 referenced an alternative
criterion for RA that would apply in instances where the emission level
for the test is less than 50 percent of the applicable standard. The
proposed alternative criterion was for when the RM result is less than
50 percent of the emission standard and the emission standard is used
in the denominator of the equation for calculating RA to be less than
or equal to 15 percent. We received comments that asserted that this
requirement is inconsistent with other alternative RA options used in
other performance specifications. Some commenters supported the use of
an absolute value; i.e., plus or minus 1 ppm if the RM is less than 3
ppm, which they reported would be similar to the requirements for
mercury CEMS under subpart UUUUU.
    We recognize that calibration standards and measurement technology
exist to demonstrate the quality of HCl emission measurements at or
above 1 ppm and that existing CEMS measurement technology can meet PS-
18 RA requirements (see Docket Nos. EPA-HQ-OAR-2013-0696-0030 and
0031). For HCl emission limits equal to or less than 1 ppm, RA is
measured

nearer the quantitation limit of current instrument technology, and an
alternative RA acceptance criterion similar to that in PS-2 of 40 CFR
part 60, appendix B may be applicable. Therefore, we have revised the
alternative criterion for RA in section 13.4 of PS-18 to allow, where
the average RM level during the test is less than 75 percent of the
applicable emission limit, substitution of the equivalent emission
limit in parts per million by volume wet (ppmvw) in the denominator of
the equation for calculating RA. Note that this revision applies to
both PS-18 and section 6 of Procedure 6.

V. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was,
therefore, not submitted to the Office of Management and Budget (OMB)
for review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under
the PRA. This action provides performance criteria and QA test
procedures for assessing the acceptability of HCl CEMS performance and
data quality. These criteria and QA test procedures do not add
information collection requirements beyond those currently required
under the applicable regulation.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. This action
provides facilities with an alternative to PS-15 and FTIRs for
measuring HCl which is currently required in several rules.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local or tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications as specified in
Executive Order 13175. This action finalizes performance specifications
that can be used as an additional option to PS-15 for HCl continuous
emissions monitoring. Thus, Executive Order 13175 does not apply to
this action.

G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

    The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. This action is not subject to
Executive Order 13045 because it does not concern an environmental
health risk or safety risk.

H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action will not have disproportionately
high and adverse human health or environmental effects on minority or
low-income populations because it does not affect the level of
protection provided to human health or the environment. This action
will help to ensure that emission control devices are operated properly
and maintained as needed, thereby helping to ensure compliance with
emission standards, which would benefit all affected populations.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and the EPA will submit a rule
report to each House of the Congress and to the Comptroller General of
the United States. This action is not a ``major rule'' as defined by 5
U.S.C. 804(2).

List of Subjects in 40 CFR Part 60

    Environmental protection, Administrative practice and procedure,
Air pollution control, Continuous emission monitoring systems, Hydrogen
chloride, Performance specifications, Test methods and procedures.

    Dated: June 25, 2015.
Gina McCarthy,
Administrator.
    Part 60, chapter I, title 40 of the Code of Federal Regulations is
amended as follows:

PART 60--STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES

0
1. The authority citation for part 60 continues to read as follows:

    Authority: 42 U.S.C. 7401-7601.

0
2. Appendix B to part 60 is amended by adding Performance Specification
18 to read as follows:

Appendix B to Part 60--Performance Specifications

* * * * *
    Performance Specification 18--Performance Specifications and
Test Procedures for Gaseous Hydrogen Chloride (HCI) Continuous
Emission Monitoring Systems at Stationary Sources

1.0 Scope and Application

    1.1 Analyte. This performance specification (PS) is applicable
for measuring gaseous concentrations of hydrogen chloride (HCl),
CAS: 7647-01-0, on a continuous basis in the units of the applicable
standard or in units that can be converted to units of the
applicable standard(s).
    1.2 Applicability.
    1.2.1 This specification is used to evaluate the acceptability
of HCl continuous emission monitoring systems (CEMS) at the time of
installation or soon after and whenever specified in the
regulations. The specification includes requirements for initial
acceptance including instrument accuracy and stability assessments
and use of audit samples if they are available.
    1.2.2 The Administrator may require the operator, under section
114 of the Clean Air Act, to conduct CEMS performance evaluations at
other times besides the initial test to evaluate the CEMS
performance. See 40 CFR part 60, Sec. Sec.  60.13(c) and 63.8(e)(1).
    1.2.3 A source that demonstrates their CEMS meets the criteria
of this PS may use the system to continuously monitor gaseous HCl
under any regulation or permit that requires compliance with this
PS. If your CEMS is capable of reporting the HCl concentration in
the units of the applicable standard, no additional CEMS components
are necessary. If your CEMS does not report concentrations in the
units of the existing standard, then other CEMS components (e.g.,

oxygen (O2), temperature, stack gas flow, moisture and
pressure) may be necessary to convert the units reported by your
CEMS to the units of the standard.
    1.2.4 These specification test results are intended to be valid
for the life of the system. As a result, the HCl measurement system
must be tested and operated in a configuration consistent with the
configuration that will be used for ongoing continuous emissions
monitoring.
    1.2.5 Substantive changes to the system configuration require
retesting according to this PS. Examples of such conditions include,
but are not limited to: major changes in dilution ratio (for
dilution based systems); changes in sample conditioning and
transport, if used, such as filtering device design or materials;
changes in probe design or configuration and changes in materials of
construction. Changes consistent with instrument manufacturer
upgrade that fall under manufacturer's certification do not require
additional field verification. Manufacturer's upgrades require
recertification by the manufacturer for those requirements allowed
by this PS, including interference, level of detection (LOD), and
light intensity qualification.
    1.2.6 This specification is not designed to evaluate the ongoing
CEMS performance nor does it identify specific calibration
techniques and auxiliary procedures to assess CEMS performance over
an extended period of time. The requirements in appendix F,
Procedure 6 are designed to provide a way to assess CEMS performance
over an extended period of time. The source owner or operator is
responsible to calibrate, maintain, and operate the CEMS properly.

2.0 Summary of Performance Specification

    2.1 This specification covers the procedures that each CEMS must
meet during the performance evaluation test. Installation and
measurement location specifications, data reduction procedures, and
performance criteria are included.
    2.2 The technology used to measure gaseous HCl must provide a
distinct response and address any appropriate interference
correction(s). It must accurately measure gaseous HCl in a
representative sample (path or point sampling) of stack effluent.
    2.3 The relative accuracy (RA) must be established against a
reference method (RM) (i.e., Method 26A, Method 320, ASTM
International (ASTM) D6348-12, including mandatory annexes, or
Method 321, as appropriate for the source concentration and
category). Method 26 may be approved as a RM by the Administrator on
a case-by-case basis if not otherwise allowed or denied in an
applicable subpart of the regulations.
    2.4 A standard addition (SA) procedure using a reference
standard is included in appendix A to this performance specification
for use in verifying LOD. For extractive CEMS, where the SA is done
by dynamic spiking (DS), the appendix A procedure is allowed as an
option for assessing calibration drift and is also referenced by
Procedure 6 of appendix F to this part for ongoing quality control
tests.

3.0 Definitions

    3.1 Calibration Cell means a gas containment cell used with
cross stack or integrated path (IP) CEMS for calibration and to
perform many of the test procedures required by this performance
specification. The cell may be a removable sealed cell or an
evacuated and/or purged cell capable of exchanging reference and
other calibration gases as well as zero gas standards. When charged,
it contains a known concentration of HCl and/or interference gases.
The calibration cell is filled with zero gas or removed from the
optical path during stack gas measurement.
    3.2 Calibration Drift (CD) means the absolute value of the
difference between the CEMS output response and an upscale reference
gas or a zero-level gas, expressed as a percentage of the span
value, when the CEMS is challenged after a stated period of
operation during which no unscheduled adjustments, maintenance or
repairs took place.
    3.3 Centroidal Area means a central area that is geometrically
similar to the stack or duct cross section and is no greater than 10
percent of the stack or duct cross-sectional area.
    3.4 Continuous Emission Monitoring System (CEMS) means the total
equipment required to measure the pollutant concentration or
emission rate continuously. The system generally consists of the
following three major subsystems:
    3.4.1 Sample Interface means that portion of the CEMS used for
one or more of the following: sample acquisition, sample transport,
sample conditioning, defining the optical measurement path, and
protection of the monitor from the effects of the stack effluent.
    3.4.2 HCl Analyzer means that portion of the HCl CEMS that
measures the total vapor phase HCl concentration and generates a
proportional output.
    3.4.3 Data Recorder means that portion of the CEMS that provides
a permanent electronic record of the analyzer output. The data
recorder may record other pertinent data such as effluent flow
rates, various instrument temperatures or abnormal CEMS operation.
The data recorder may also include automatic data reduction
capabilities and CEMS control capabilities.
    3.5 Diluent Gas means a major gaseous constituent in a gaseous
pollutant mixture. For combustion sources, either carbon dioxide
(CO2) or oxygen (O2) or a combination of these two gases are the
major gaseous diluents of interest.
    3.6 Dynamic Spiking (DS) means the procedure where a known
concentration of HCl gas is injected into the probe sample gas
stream for extractive CEMS at a known flow rate to assess the
performance of the measurement system in the presence of potential
interference from the flue gas sample matrix.
    3.7 Independent Measurement(s) means the series of CEMS data
values taken during sample gas analysis separated by two times the
procedure specific response time (RT) of the CEMS.
    3.8 Integrated Path CEMS (IP-CEMS) means an in-situ CEMS that
measures the gas concentration along an optical path in the stack or
duct cross section.
    3.9 Interference means a compound or material in the sample
matrix other than HCl whose characteristics may bias the CEMS
measurement (positively or negatively). The interference may not
prevent the sample measurement, but could increase the analytical
uncertainty in the measured HCl concentration through reaction with
HCl or by changing the electronic signal generated during HCl
measurement.
    3.10 Interference Test means the test to detect CEMS responses
to interferences that are not adequately accounted for in the
calibration procedure and may cause measurement bias.
    3.11 Level of Detection (LOD) means the lowest level of
pollutant that the CEMS can detect in the presence of the source gas
matrix interferents with 99 percent confidence.
    3.12 Liquid Evaporative Standard means a reference gas produced
by vaporizing National Institute of Standards and Technology (NIST)
traceable liquid standards of known HCl concentration and
quantitatively diluting the resultant vapor with a carrier gas.
    3.13 Measurement Error (ME) is the mean difference between the
concentration measured by the CEMS and the known concentration of a
reference gas standard, divided by the span, when the entire CEMS,
including the sampling interface, is challenged.
    3.14 Optical Path means the route light travels from the light
source to the receiver used to make sample measurements.
    3.15 Path Length means, for an extractive optical CEMS, the
distance in meters of the optical path within a gas measurement
cell. For an IP-CEMS, path length means the distance in meters of
the optical path that passes through the source gas in the stack or
duct.
    3.16 Point CEMS means a CEMS that measures the source gas
concentration, either at a single point at the sampling probe tip or
over a path length for IP-CEMS less than 10 percent of the
equivalent diameter of the stack or duct cross section.
    3.17 Stack Pressure Measurement Device means a NIST-traceable
gauge or monitor that measures absolute pressure and conforms to the
design requirements of ASME B40.100-2010, ``Pressure Gauges and
Gauge Attachments'' (incorporated by reference--see Sec.  60.17).
    3.18 Reference Gas Standard means a NIST-traceable gas standard
containing a known concentration of HCl certified in accordance with
an EPA traceability protocol in section 7.1 of this PS.
    3.19 Relative Accuracy (RA) means the absolute mean difference
between the gas concentration or the emission rate determined by the
CEMS and the value determined by the RM, plus the confidence
coefficient of a series of nine test runs, divided by the average of
the RM or the applicable emission standard.
    3.20 Response Time (RT) means the time it takes for the
measurement system, while operating normally at its target sample
flow rate, dilution ratio, or data collection rate to

respond to a known step change in gas concentration, either from a
low- or zero-level to a high-level gas concentration or from a high-
level to a low or zero-level gas concentration, and to read 95
percent of the change to the stable instrument response. There may
be several response times (RTs) for an instrument related to
different functions or procedures (e.g., DS, LOD, and ME).
    3.21 Span Value means an HCl concentration approximately equal
to two times the concentration equivalent to the emission standard
unless otherwise specified in the applicable regulation, permit or
other requirement. Unless otherwise specified, the span may be
rounded up to the nearest multiple of 5.
    3.22 Standard Addition means the addition of known amounts of
HCl gas (either statically or dynamically) to the actual measurement
path or measured sample gas stream.
    3.23 Zero gas means a gas or liquid with an HCl concentration
that is below the LOD of the measurement system.

4.0 Interferences

    Sample gas interferences will vary depending on the instrument
or technology used to make the measurement. Interferences must be
evaluated through the interference test in this PS. Several
compounds including carbon dioxide (CO2), carbon monoxide
(CO), formaldehyde (CH2O), methane (CH4), and
water (H2O) are potential optical interferences with
certain types of HCl monitoring technology. Ammonia is a potential
chemical interference with HCl.

5.0 Safety

    The procedures required under this PS may involve hazardous
materials, operations, and equipment. This PS may not address all of
the safety issues associated with these procedures. It is the
responsibility of the user to establish appropriate safety and
health practices and determine the applicable regulatory limitations
prior to performing these procedures. The CEMS user's manual and
materials recommended by the RM should be consulted for specific
precautions to be taken.

6.0 Equipment and Supplies

    Equipment and supplies for CEMS will vary depending on the
measurement technology and equipment vendors. This section provides
a description of the equipment and supplies typically found in one
or more types of CEMS.
    6.1 Sample Extraction System. The portion of an extractive CEMS
that collects and transports the sample to the pressure regulation
and sample conditioning module. The extraction system must deliver a
representative sample to the measurement instrument. The sample
extraction system typically consists of a sample probe and a heated
umbilical line.
    6.2 Sample Conditioning Module. The portion of an extractive
CEMS that removes particulate matter and moisture from the gas
stream and provides a sample gas stream to the CEMS analysis module
or analyzer. You must keep the particle-free gas sample above the
dew point temperature of its components.
    6.3 HClAnalyzer. The portion of the CEMS that detects,
quantifies and generates an output proportional to the sample gas
HCl concentration.
    6.4 System Controller. The portion of the CEMS that provides
control of the analyzer and other sub-systems (e.g., sample
extraction, sample conditioning, reference gas) as necessary for
continuous operation and periodic maintenance/QC activities.
    6.5 Data Recorder. The portion of the CEMS that provides a
record of analyzer output. The data recorder may record other
pertinent data such as effluent flow rates, various instrument
temperatures or abnormal CEMS operation. The data recorder output
range must include the full range of expected HCl concentration
values in the gas stream to be sampled including zero and span
value.
    6.6 Reference Gas System(s). Gas handling system(s) needed to
introduce reference and other gases into the measurement system. For
extractive CEMS, the system must be able to introduce gas flow
sufficient to flood the sampling probe and prevent entry of gas from
the effluent stream. For IP-CEMS, the system must be able to
introduce a known concentration of HCl, at known cell length,
pressure and temperature, into the optical path used to measure HCl
gas concentration.
    6.7 Moisture Measurement System. If correction of the measured
HCl emissions for moisture is required, you must install, operate,
maintain, and quality assure a continuous moisture monitoring system
for measuring and recording the moisture content of the flue gases.
The following continuous moisture monitoring systems are acceptable:
An FTIR system validated according to Method 301 or section 13.0 of
Method 320 in appendix A to part 63 of this chapter; a continuous
moisture sensor; an oxygen analyzer (or analyzers) capable of
measuring O2 both on a wet basis and on a dry basis; a
stack temperature sensor and a moisture look-up table, i.e., a
psychrometric chart (for saturated gas streams following wet
scrubbers or other demonstrably saturated gas streams, only); or
other continuous moisture measurement methods approved by the
Administrator. Alternatively, for any type of fuel, you may
determine an appropriate site-specific default moisture value (or
values), using measurements made with Method 4--Determination of
Moisture Content In Stack Gases, in appendix A-3 to of this part. If
this option is selected, the site-specific moisture default value(s)
must represent the fuel(s) or fuel blends that are combusted in the
unit during normal, stable operation, and must account for any
distinct difference(s) in the stack gas moisture content associated
with different process operating conditions. At least nine Method 4
runs are required for determining each site-specific default
moisture percentage. Calculate each site-specific default moisture
value by taking the arithmetic average of the Method 4 runs. Each
site-specific moisture default value shall be updated whenever the
current value is non-representative, due to changes in unit or
process operation, but in any event no less frequently than
annually.

7.0 Reagents and Standards

    7.1 Reference Gases. Reference gases (e.g., cylinder gases or
liquid evaporative standards) used to meet the requirements of this
PS must be NIST certified or NIST-traceable and vendor certified to
5.0 percent accuracy. HCl cylinder gases must be
certified according to Reference 5 in section 16 of this PS through
a documented unbroken chain of comparisons each contributing to the
reported uncertainty. Liquid evaporative standards must be certified
using the gravimetrically-based procedures of the latest version of
the EPA Traceability Protocol for Qualification and Certification of
Evaporative HCl Gas Standards and Humidification of HCl Gas
Standards from Cylinders (see EPA-HQ-OAR-2013-0696-0026.pdf).
    7.2 Cylinder gas and/or liquid evaporative standards must be
used within their certification periods.
    7.3 High concentration cylinder gas or liquid evaporative HCl
standards may be diluted for use in this specification. You must
document the quantitative introduction of HCl standards into the
system using Method 205, found in 40 CFR part 51, appendix M, or
other procedure approved by the Administrator.

8.0 CEMS Measurement Location Specifications and Pretest Preparation

    8.1 Prior to the start of your initial PS tests, you must ensure
that the CEMS is installed according to the manufacturer's
specifications and the requirements in this section. You may use
either point or IP sampling technology.
    8.2 CEMS Installation. Install the CEMS at an accessible
location where the pollutant concentration or emission rate
measurements are directly representative of the HCl emissions or can
be corrected so as to be representative of the total emissions from
the affected facility. The CEMS need not be installed at the same
location as the relative accuracy test location. If you fail the RA
requirements in this specification due to the CEMS measurement
location and a satisfactory correction technique cannot be
established, the Administrator may require the CEMS to be relocated.
    8.2.1 Single point sample gas extraction should be (1) no less
than 1.0 m (3.3 ft.) from the stack or duct wall or (2) within the
centroidal area of the stack or duct cross section.
    8.2.2 IP-CEMS measurements should (1) be conducted totally
within the inner area bounded by a line 1.0 m (3.3 ft.) from the
stack or duct wall, (2) have at least 70 percent of the path within
the inner 50 percent of the stack or duct cross-sectional area, or
(3) be located over any part of the centroidal area.
    <IP_ADDRESS> You must measure the IP-CEMS path length from the inner
flange of the sampling ports or the inner end of the instrument
insertion into the stack cavity using a laser tape measure,
mechanical measurement tape, or similar device accurate to 1.5 mm (0.059 in).
    <IP_ADDRESS> You must ensure that any purge flow used to protect IP-
CEMS instrument windows from stack gas does not alter the
measurement path length. Purge flow of less

than or equal to 10 percent of the gas velocity in the duct meets
this requirement.
    8.2.3 CEMS and Data Recorder Scale Check. After CEMS
installation, record and document the measurement range of the HCl
CEMS. The CEMS operating range and the range of the data recording
device must encompass all potential and expected HCl concentrations,
including the concentration equivalent to the applicable emission
limit and the span value.

9.0 Quality Control [Reserved]

10.0 Calibration and Standardization [Reserved]

11.0 Performance Specification Test Procedure

    After completing the CEMS installation, setup and calibration,
you must complete the PS test procedures in this section. You must
perform the following procedures and meet the performance
requirements for the initial demonstration of your CEMS:
    a. Interference Test;
    b. Beam Intensity Test (IP-CEMS only);
    c. Temperature Verification Procedure (IP-CEMS only);
    d. Pressure Verification Procedure (IP-CEMS only);
    e. Level of Detection Determination;
    f. Response Time Test;
    g. Measurement Error Test;
    h. Calibration Drift Test; and
    i. Relative Accuracy Test.

11.1 Interference Test

    11.1.1 Prior to its initial use in the field, you must
demonstrate that your monitoring system meets the performance
requirements of the interference test in section 13.5 to verify that
the candidate system measures HCl accurately in the presence of
common interferences in emission matrices.
    11.1.2 Your interference test must be conducted in a controlled
environment. The equipment you test for interference must include
the combination of the analyzer, related analysis software, and any
sample conditioning equipment (e.g., dilution module, moisture
removal equipment or other interferent scrubber) used to control
interferents.
    11.1.3 If you own multiple measurement systems with components
of the same make and model numbers, you need only perform this
interference test on one analyzer and associated interference
conditioning equipment combination. You may also rely on an
interference test conducted by the manufacturer or a continuous
measurement system integrator on a system having components of the
same make and model(s) of the system that you use.
    11.1.4 Perform the interference check using an HCl reference gas
concentration of approximately five times the LOD.
    11.1.5 Introduce the interference test gases listed in Table 1
in section 17.0 of this PS to the analyzer/conditioning system
separately or in any combination. The interference test gases need
not be of reference gas quality.
    <IP_ADDRESS> For extractive CEMS, the interference test gases may be
introduced directly into the inlet to the analyzer/conditioning
system after the probe extension coupling.
    <IP_ADDRESS> For IP-CEMS, the interference test gases may be added
with the HCl in a calibration cell or separately in a temperature-
controlled cell. The effective concentration of the gas in the cell
must meet the requirements in Table 1 corrected for absolute
pressure, temperature and the nominal stack sampling path length of
the CEMS.
    11.1.6 The interference test must be performed by combining an
HCl reference gas with each interference test gas (or gas mixture).
You must measure the baseline HCl response, followed by the response
after adding the interference test gas(es) while maintaining a
constant HCl concentration. You must perform each interference gas
injection and evaluation in triplicate.
    Note: The baseline HCl gas may include interference gases at
concentrations typical of ambient air (e.g., 21 percent
O2, 400 parts per million (ppm) CO2, 2 percent
H2O), but these concentrations must be brought to the
concentrations listed in Table 1 when their interference effects are
being evaluated.
    11.1.7 You should document the gas volume/rate, temperature, and
pressure used to conduct the interference test. A gas blending
system or manifold may be used.
    11.1.8 Ensure the duration of each interference test is
sufficient to condition the HCl measurement system surfaces before a
stable measurement is obtained.
    11.1.9 Measure the HCl response of the analyzer/sample
conditioning system combination to the test gases in ppmv. Record
the responses and determine the overall interference response using
Table 2 in section 17.0.
    11.1.10 For each interference gas (or mixture), calculate the
mean difference ([Delta]MCavg) between the measurement
system responses with and without the interference test gas(es)
using Equation 1 in section 12.2. Summarize the results following
the format contained in Table 2 in section 17.
    11.1.11 Calculate the percent interference (I) for the gas runs
using Equation 2 in section 12.2.
    11.1.12 The total interference response (i.e., the sum of the
interference responses of all tested gaseous components) must not
exceed the criteria set forth in section 13.5 of this PS.

11.2 Beam Intensity Test for IP-CEMS

    11.2.1 For IP-CEMS, you must establish the tolerance of your
system to beam intensity attenuation.
    <IP_ADDRESS> Your beam intensity test may be conducted in either a
controlled environment or on-site during initial setup and
demonstration of your CEMS.
    <IP_ADDRESS> If you have multiple measurement systems with
components of the same make and model numbers, you need only perform
this attenuation check on one system and you may also rely on an
attenuation test conducted by the manufacturer on a system having
components of the same make and model(s) of the system that you use.
    11.2.2 Insert one or more neutral density filter(s) or otherwise
attenuate the beam intensity by a known percentage (e.g., 90 percent
of the beam intensity).
    11.2.3 Perform a high-level HCl reference gas measurement.
    11.2.4 Record and report the attenuated beam intensity, the
measured HCl calibration gas concentration at full beam intensity,
the measured HCl gas concentration with attenuated beam intensity,
and the percent difference between the two HCl measurements with and
without attenuation of the beam intensity. The percent difference
must not exceed the criteria set forth in section 13.6 of this PS.
    11.2.5 In the future, you may not operate your IP-CEMS at a beam
intensity lower than that established based on the attenuation used
during this test. However, you may repeat the test to establish a
lower beam intensity limit or level.

11.3 Temperature Measurement Verification Procedure for IP-CEMS

    11.3.1 Any measurement instrument or device that is used as a
reference in verification of temperature measurement must have an
accuracy that is traceable to NIST.
    11.3.2 You must verify the temperature sensor used in IP-CEMS
measurements on-site as part of the initial installation and
verification procedures.
    11.3.3 Comparison to Calibrated Temperature Measurement Device.
    <IP_ADDRESS> Place the sensor of a calibrated temperature reference
device adjacent to the sensor used to measure stack temperature for
your IP-CEMS. The calibrated temperature reference device must
satisfy the accuracy requirements specified in Table 3 of this PS.
The calibrated temperature reference device must also have a range
equal to or greater than the range of your IP-CEMS temperature
sensor.
    <IP_ADDRESS> Allow sufficient time for the response of the
calibrated temperature reference device to reach equilibrium. With
the process and control device operating under normal conditions,
concurrently record the temperatures measured by your IP-CEMS system
(Mt) and the calibrated temperature reference device
(Vt). You must meet the accuracy requirements specified
in section 13.7 of this PS.
    <IP_ADDRESS> If your IP-CEMS temperature sensor does not satisfy the
accuracy requirement of this PS, check all system components and
take any corrective action that is necessary to achieve the required
minimum accuracy. Repeat this verification procedure until the
accuracy requirement of this specification is satisfied.

11.4 Pressure Measurement Verification Procedure for IP-CEMS

    11.4.1 For stack pressure measurement verification, you must
select a NIST-traceable gauge or monitor that conforms to the design
requirements of ASME B40.100-2010, ``Pressure Gauges and Gauge
Attachments,'' (incorporated by reference--see Sec.  60.17) as a
reference device.
    11.4.2 As an alternative for a calibrated pressure reference
device with NIST-traceable accuracy, you may use a water-in-glass U-
tube manometer to verify your IP-

CEMS pressure measurement equipment, provided there is also an
accurate measurement of absolute atmospheric pressure at the
manometer location.
    11.4.3 Allow sufficient time for the response of the reference
pressure measurement device to reach equilibrium. With the process
and control device operating under normal conditions, concurrently
record the pressures measured by your IP-CEMS system (MP)
and the pressure reference device (Vp). You must meet the
accuracy requirements specified in section 13.8 of this PS.
    11.4.4 If your IP-CEMS pressure sensor does not satisfy the
accuracy requirement of this PS, check all system components and
take any corrective action that is necessary to achieve the required
minimum accuracy. Repeat this verification procedure until the
accuracy requirement of this specification is satisfied.

11.5 Level of Detection Determination

    11.5.1 You must determine the minimum amount of HCl that can be
detected above the background in a representative gas matrix.
    11.5.2 You must perform the LOD determination in a controlled
environment such as a laboratory or manufacturer's facility.
    11.5.3 You must add interference gases listed in Table 1 of this
PS to a constant concentration of HCl reference gas.
    <IP_ADDRESS> You may not use an effective reference HCl gas
concentration greater than five times the estimated instrument LOD.
    <IP_ADDRESS> For extractive CEMS, inject the HCl and interferents
described in section 11.1.5 directly into the inlet to the analyzer.
    <IP_ADDRESS> For IP-CEMS, the HCl and interference test gases may be
added to a calibration cell or separately in a temperature-
controlled cell that is part of the measurement path. The effective
concentration of the gas in the cell must meet the requirements in
Table 1 corrected for absolute pressure, temperature and the nominal
stack sampling path length of the CEMS.
    11.5.4 Collect seven or more consecutive measurements separated
by twice the RT (described in section 11.6) to determine the LOD.
    11.5.5 Calculate the standard deviation of the measured values
and define the LOD as three times the standard deviation of these
measurements.
    <IP_ADDRESS> The LOD for extractive units must be determined and
reported in ppmv.
    <IP_ADDRESS> The LOD for IP units must be determined and reported on
a ppm-meter basis and the site- or installation-specific LOD must be
calculated based on the actual measurement path length and gas
density of the emissions at the specific site installation in ppmv.
    11.5.6 You must verify the controlled environment LOD of section
11.5.2 of this PS for your CEMS during initial setup and field
certification testing. You must use the SA procedure in appendix A
of this PS with the following exceptions:
    <IP_ADDRESS> For the LOD verification in the field, you must make
three independent SA measurements spiking the native source
concentration by no more than three times the controlled environment
LOD concentration determined in section 11.5.5.
    <IP_ADDRESS> For extractive CEMS, you must perform the SA as a
dynamic spike by passing the spiked source gas sample through all
filters, scrubbers, conditioners and other monitoring system
components used during normal sampling, and as much of the sampling
probe as practical. For IP-CEMS, you must perform the SA procedure
by adding or passing a known concentration reference gas into a
calibration cell in the optical path of the CEMS; you must also
include the source measurement optical path while performing the SA
measurement.
    <IP_ADDRESS> The amount detected, or standard addition response
(SAR), is based on the average difference of the native HCl
concentration in the stack or duct relative to the native stack
concentration plus the SA. You must be able to detect the effective
spike addition (ESA) above the native HCl present in the stack gas
matrix. For extractive CEMS, the ESA is calculated using Equation A7
in appendix A of this PS. For IP-CEMS, the ESA is calculated as
Ci,eff using Equation 4 of this PS.
    <IP_ADDRESS> For extractive CEMS, calculate the SAR using Equation
A4 in appendix A of this PS. For IP-CEMS, calculate the SAR using
Equation A8.
    <IP_ADDRESS> If your system LOD field verification does not
demonstrate a SAR greater than or equal to your initial controlled
environment LOD, you must increase the SA concentration
incrementally and repeat the field verification procedure until the
SAR is equal to or greater than LOD. The site-specific standard
addition detection level (SADL) is equal to the standard addition
needed to achieve the acceptable SAR, and SADL replaces the
controlled environment LOD. For extractive CEMS, the SADL is
calculated as the ESA using Equation A7 in appendix A of this PS.
For IP-CEMS, the SADL is the SA calculated using Equation A8 in
appendix A of this PS. As described in section 13.1 of this PS, the
SADL must be less than 20 percent of the applicable emission limit.

11.6 Response Time Determination. You must determine ME-, LOD- and
SA-RT

    11.6.1 For ME- or LOD-RT, start the upscale RT determination by
injecting zero gas into the measurement system as required by the
procedures in section 11.7 or 11.5, respectively. You may use
humidified zero gas. For standard addition RT, start the upscale RT
determination by measuring the native stack gas concentration of
HCl.
    <IP_ADDRESS> For extractive CEMS measuring ME- or LOD-RT, the output
has stabilized when there is no change greater than 1.0 percent of
full scale for 30 seconds.
    <IP_ADDRESS> For standard addition RT that includes the stack gas
matrix the final stable response may continue to vary by more than 1
percent, but may be considered stable if the variability is random
and not continuously rising or falling.
    11.6.2 When the CEMS output has stabilized, record the response
in ppmv and introduce an upscale (high level) or spike reference gas
as required by the relevant procedure.
    11.6.3 Record the time (upscale RT) required to reach 95 percent
of the change to the final stable value.
    11.6.4 Next, for ME or LOD RT, reintroduce the zero gas and
record the time required to reach 95 percent of the change to the
stable instrument response at the zero gas reading. For SA RT,
introduce zero gas to the IP-CEMS cell or stop the spike gas flow to
the extractive CEMS as required by the specified procedure and
record the time required to reach 95 percent of the change to the
stable instrument response of the native gas reading. This time is
the downscale RT.
    (Note: For CEMS that perform a series of operations (purge, blow
back, sample integration, analyze, etc.), you must start adding
reference or zero gas immediately after these procedures are
complete.)
    11.6.5 Repeat the entire procedure until you have three sets of
data, then determine the mean upscale and mean downscale RTs for
each relevant procedure. Report the greater of the average upscale
or average downscale RTs as the RT for the system.

11.7 Measurement Error (ME) Test

    11.7.1 On the same day and as close in time as practicable to
when the ME test is conducted, perform and meet requirements for a
calibration drift (CD) test using a zero gas as used in the Seven-
Day Drift Test (see section 11.8) and document and report the
results. To meet this requirement, the ME test may be conducted
during the Seven-Day CD Test.
    11.7.2 Extractive CEMS ME Test.
    <IP_ADDRESS> Introduce reference gases to the CEMS probe, prior to
the sample conditioning and filtration system.
    <IP_ADDRESS> Measure three upscale HCl reference gas concentrations
in the range shown in Table 4 of this PS.
    <IP_ADDRESS> Introduce the gases into the sampling probe with
sufficient flow rate to replace the entire source gas sample.
    <IP_ADDRESS> Continue to add the reference gas until the response is
stable as evidenced when the difference between two consecutive
measurements is less than the LOD or within five percent of each
other.
    <IP_ADDRESS> Make triplicate measurements for each reference gas for
a total of nine measurements. Introduce different reference gas
concentrations in any order but do not introduce the same gas
concentration twice in succession.
    <IP_ADDRESS> At each reference gas concentration, determine the
average of the three CEMS responses (MCl). Calculate the ME using
Equation 3A in section 12.3.
    <IP_ADDRESS> If you desire to determine the system RT during this
test, you must inject zero gas immediately before and after each
injection of the high-level gas standard.
    <IP_ADDRESS> For non-dilution systems, you may adjust the system to
maintain the correct flow rate at the analyzer during the test, but
you may not make adjustments for any other purpose. For dilution
systems, you must operate the measurement system at the appropriate
dilution ratio during all system ME checks, and you may make only
the adjustments necessary to maintain the proper ratio.
    11.7.3 IP-CEMS ME Test.

    <IP_ADDRESS> Conduct a 3-level system ME test by individually adding
the known concentrations of HCl reference gases into a calibration
cell of known volume, temperature, pressure and path length.
    Note: The optical path used for IP-CEMS ME checks must include
the native HCl measurement path. You must also collect native stack
concentration HCl measurements before and after each HCl standard
measurement. Bracketing HCl reference gas measurements with native
stack HCl measurements must be used in the calculations in Equation
5 in section 12.4.2 to correct the upscale measurements for stack
gas HCl concentration changes.
    <IP_ADDRESS> Introduce HCl reference gas into your calibration cell
in a range of concentrations that produce responses equivalent to
the source concentrations shown in Table 4 of this PS for your path
length.
    <IP_ADDRESS> Make triplicate measurements for each reference gas
standard for a total of nine measurements. Introduce different
calibration concentrations in any order but do not introduce the
same reference gas concentration twice in succession.
    <IP_ADDRESS> You must calculate the effective concentration
(Ci,eff) of the HCl reference gas equivalent to the stack
concentration by correcting for calibration cell temperature,
pressure, path length, line strength factor (LSF) and, if necessary,
the native stack gas HCl concentration using Equation 4 in section
12.0.
    <IP_ADDRESS> You may use the LSF provided by your instrument
manufacturer or determine an instrument-specific LSF as a function
of temperature using a heated gas cell and equivalent concentrations
(Ci,eff) between 50 and 150 percent of the emission
limit.
    <IP_ADDRESS> At each reference gas concentration, average the three
independent CEMS measurement responses corrected for native HCl
stack concentration. Calculate the ME using Equation 6A in section
12.4.3.
    11.7.4 You may use Figure 1 in section 17.0 to record and report
your ME test results.
    11.7.5 If the ME specification in section 13.3 is not met for
all three reference gas concentrations, take corrective action and
repeat the test until an acceptable 3-level ME test is achieved.

11.8 Seven-Day Calibration Drift (CD) Test

    11.8.1 The CD Test Period. Prior to the start of the RA tests,
you must perform a seven-day CD test. The purpose of the seven-day
CD test is to verify the ability of the CEMS to maintain calibration
for each of seven consecutive unit operating days as specified in
section 11.8.5 of this PS.
    11.8.2 The CD tests must be performed using the zero gas and
mid-level reference gas standards as defined in Table 4 of this PS.
    11.8.3 Conduct the CD test on each day during continuous
operation of the CEMS and normal facility operations following the
procedures in section 11.7 of this PS, except that the zero gas and
mid-level gas need only be introduced to the measurement system once
each.
    11.8.4 If periodic automatic or manual adjustments are made to
the CEMS zero and upscale response factor settings, conduct the CD
test immediately before these adjustments.
    Note: Automatic signal or mathematical processing of all
measurement data to determine emission results may be performed
throughout the entire CD process.
    11.8.5 Determine the magnitude of the CD at approximately 24-
hour intervals, for 7 consecutive unit operating days. The 7
consecutive unit operating days need not be 7 consecutive calendar
days.
    11.8.6 Record the CEMS response for single measurements of zero
gas and mid-level reference gas. You may use Figure 2 in section 17
of this PS to record and report the results of your 7-day CD test.
    <IP_ADDRESS> For extractive CEMS, calculate the CD using Equation 3B
in section 12.3. Report the absolute value of the differences as a
percentage of the span value.
    <IP_ADDRESS> For IP-CEMS, you must include the source measurement
optical path while performing the upscale CD measurement; you must
exclude the source measurement optical path when determining the
zero gas concentration. Calculate the CD for IP CEMS using Equations
4, 5, 6B, and 7 in section 12.4.
    11.8.7 The zero-level and mid-level CD for each day must be less
than 5.0 percent of the span value as specified in section 13.2 of
this PS. You must meet this criterion for 7 consecutive operating
days past the 7-day CD test.
    11.8.8 Dynamic Spiking Option for Seven-Day CD Test. For
extractive CEMS, you have the option to conduct a mid-level dynamic
spiking procedure for each of the 7 days in lieu of the mid-level
reference gas injection described in sections 11.8.2 and 11.8.3. If
this option is selected, the daily zero CD check is still required.
    <IP_ADDRESS> To conduct each of the seven daily mid-level dynamic
spikes, you must use the DS procedure described in appendix A of
this PS using a single spike of the mid-level reference gas (see
Table 4).
    <IP_ADDRESS> You must perform the dynamic spike procedure by passing
the spiked source gas sample through all filters, scrubbers,
conditioners and other monitoring system components used during
normal sampling, and as much of the sampling probe as practical.
    <IP_ADDRESS> Calculate the mid-level CD as a percent of span using
Equation A6 of appendix A to this PS and calculate the zero drift
using Equation 3B in section 12.3. Record and report the results as
described in sections 11.8.6 and 11.8.7.

11.9 Relative Accuracy Test

    11.9.1 Unless otherwise specified in an applicable regulation,
use Method 26A in 40 CFR part 60, appendix A-8, Method 320 or Method
321, both found in 40 CFR part 63, appendix A, or ASTM D6348-12
including all annexes, as applicable, as the RMs for HCl
measurement. Obtain and analyze RM audit samples, if they are
available, concurrently with RM test samples according to the same
procedure specified for performance tests in the general provisions
of the applicable part. If Method 26 is not specified in an
applicable subpart of the regulations, you may request approval to
use Method 26 in appendix A-8 to this part as the RM on a site-
specific basis under Sec. Sec.  63.7(f) or 60.8(b). Other RMs for
moisture, O2, etc., may be necessary. Conduct the RM
tests in such a way that they will yield results representative of
the emissions from the source and can be compared to the CEMS data.
    <IP_ADDRESS> When Method 26A is used as the RM, you must sample
sufficient gas to reach three times your method detection limit for
Method 26A in 40 CFR part 60, appendix A-8, or for a minimum of one
hour, whichever is greater.
    <IP_ADDRESS> When Method 320 or Method 321, both found in 40 CFR
part 63, appendix A, or ASTM D6348-12, are used as the RM, you must
collect gas samples that are at stack conditions (hot and wet) and
you must traverse as required in section 11.9.3.
    11.9.2 Conduct the diluent (if applicable), moisture (if
needed), and pollutant measurements simultaneously. However, diluent
and moisture measurements that are taken within an hour of the
pollutant measurements may be used to calculate dry pollutant
concentration and emission rates.
    11.9.3 Reference Method Measurement Location and Traverse
Point(s) Selection.
    <IP_ADDRESS> Measurement Location. Select, as appropriate, an
accessible RM measurement location at least two equivalent diameters
downstream from the nearest control device, point of pollutant
generation, or other point at which a change in the pollutant
concentration or emission rate may occur, and at least one half
equivalent diameter upstream from the effluent exhaust or a control
device. When pollutant concentration changes are due solely to
diluent leakage (e.g., air heater leakages) and pollutants and
diluents are simultaneously measured at the same location, a half
diameter may be used in lieu of two equivalent diameters. The
equivalent duct diameter is calculated according to Method 1 in
appendix A-1 to this part. The CEMS and RM sampling locations need
not be the same.
    <IP_ADDRESS> Traverse Point Selection. Select traverse points that
assure acquisition of representative RM samples over the stack or
duct cross section according to one of the following options: (a)
sample at twelve traverse points located according to section 11.3
of Method 1 in appendix A-1 to this part, (b) sample at 6 Method 1
traverse points according to section 6.5.6(b)(1) of appendix A to
part 75 of this chapter, or (c) sample at three points on a
measurement line (``3-point long line'') that passes through the
centroidal area of the duct in the direction of any potential
stratification. If this line interferes with the CEMS measurements,
you may displace the line up to 20 cm (12 in.) or 5.0 percent of the
equivalent diameter of the cross section, whichever is less, from
the centroidal area. Locate the three traverse points at 16.7, 50.0,
and 83.3 percent of the measurement line. Alternatively, you may
conduct a stratification test following the procedures in sections
<IP_ADDRESS>.1 through <IP_ADDRESS>.4 to justify sampling at a single point
or three points located on the measurement line at 0.4, 1.2, and 2.0
m from the stack wall (``3-point short line''). Stratification
testing must be conducted at the sampling location

to be used for the RM measurements during the RA test and must be
made during normal facility operating conditions. You must evaluate
the stratification by measuring the gas on the same moisture basis
as the HCl CEMS (wet or dry). Stratification testing must be
repeated for each RA test program to justify single point or ``3-
point short line'' sampling.
    <IP_ADDRESS>.1 Use a probe of appropriate length to measure the HCl
concentration or an alternative analyte, as described in this
section, using 12 traverse points located according to section 11.3
of Method 1 in appendix A-1 to 40 CFR part 60 for a circular stack
or nine points at the centroids of similarly-shaped, equal area
divisions of the cross section of a rectangular stack.
    <IP_ADDRESS>.2 You may substitute a stratification test for
SO2 for the HCl stratification test. If you select this
option, you must follow the test procedures in Method 6C of appendix
A-4 to 40 CFR part 60 or Method 320 of appendix A of 40 CFR part 63.
    <IP_ADDRESS>.3 Calculate the mean measured concentration for all
sampling points (MNavg).
    <IP_ADDRESS>.4 Calculate the percent stratification (St)
of each traverse point using Equation 8 in section 12.5.
    <IP_ADDRESS>.5 The gas stream is considered to be unstratified and
you may perform the RA testing at a single point that most closely
matches the mean if the concentration at each traverse point differs
from the mean concentration for all traverse points by: (a) No more
than 5.0 percent of the mean concentration; or (b) 0.2 ppm (for HCl)
or 3 ppm (for SO2) absolute, whichever is less
restrictive.
    <IP_ADDRESS>.6 If the criterion for single point sampling (5.0
percent, 0.2 ppm for HCl or 3 ppm for SO2 are not met,
but the concentration at each traverse point differs from the mean
concentration for all traverse points by no more than 10.0 percent
of the mean, the gas stream is considered to be minimally
stratified, and you may take RA samples using the ``3-point short
line''. Alternatively, you may use the 3-point short line if each
traverse point differs from the mean value by no more than 0.4 ppm
(for HCl) or 5 ppm (for SO2).
    <IP_ADDRESS>.7 If the concentration at any traverse point differs
from the mean concentration by more than 10 percent, the gas stream
is considered stratified and you must sample using one of the
options in section <IP_ADDRESS> above.
    <IP_ADDRESS> Conduct all necessary RM tests within 3 cm (1.2 in.) of
the traverse points, but no closer than 3 cm (1.2 in.) to the stack
or duct wall.
    11.9.4 In order to correlate the CEMS and RM data properly,
record the beginning and end of each RM run (including the time of
day in hours, minutes, and seconds) using a clock synchronized with
the CEM clock used to create a permanent time record with the CEMS
output.
    11.9.5 You must conduct the RATA during representative process
and control operating conditions or as specified in an applicable
regulation, permit or subpart.
    11.9.6 Conduct a minimum of nine RM test runs. NOTE: More than
nine RM test runs may be performed. If this option is chosen, up to
three test run results may be excluded so long as the total number
of test run results used to determine the CEMS RA is greater than or
equal to nine. However, all data must be reported including the
excluded test runs.
    11.9.7 Analyze the results from the RM test runs using Equations
9-14 in section 12.6. Calculate the RA between the CEMS results and
the RM.

11.10 Record Keeping and Reporting

    11.10.1 For systems that use a liquid evaporative standard
generator to deliver HCl reference gas standards, record supporting
data for these devices, including liquid feed calibrations, liquid
standard concentration(s) and NIST-traceability, feed rate and gas
flow calibrations for all diluent and HCl gas flows. All
calibrations must include a stated uncertainty, and the combined
uncertainty of the delivered HCl reference gas concentration must be
calculated and reported.
    11.10.2 Record the results of the CD test, the RT test, the ME
test, the RA test, and for IP-CEMS, the results of the beam
intensity, temperature and pressure verification procedures. Also
keep records of the RM and CEMS field data, calculations, and
reference gas certifications necessary to confirm that the
performance of the CEMS met the performance specifications.
    11.10.3 For systems that use Method 205 to prepare HCl reference
gas standards, record results of Method 205 performance test field
evaluation, reference gas certifications, and gas dilution system
calibration.
    11.10.4 Record the LOD for the CEMS. For extractive CEMS, record
the LOD in ppmv. For IP-CEMS, record the LOD on a ppm-meter basis
along with a calculation of the installation specific LOD in ppmv.
For both CEMS types, you must also record the field verified SADL.
    11.10.5 Record the results of the interference test.
    11.10.6 Report the results of all certification tests to the
appropriate regulatory agency (or agencies), in hardcopy and/or
electronic format, as required by the applicable regulation or
permit.

12.0 Calculations and Data Analysis

12.1 Nomenclature

Ci = Zero HCl reference gas concentration used for test i
(ppmv);
Ci,eff = Equivalent concentration of the reference gas
value, Ci, at the specified conditions (ppmv);
CC = Confidence coefficient (ppmv);
CDextractive = Calibration drift for extractive CEMS
(percent);
CDIP = Calibration drift for IP-CEMS (percent);
CD0 = Calibration drift at zero HCl concentrations for an
IP-CEMS (percent);
davg = Mean difference between CEMS response and the
reference gas (ppmv);
di = Difference of CEMS response and the RM value (ppmv);
I = Total interference from major matrix stack gases, (percent);
LSF = Line strength factor for IP-CEMS instrument specific
correction for temperature and gas matrix effects derived from the
HITRAN and/or manufacturer specific database (unitless);
[Delta]MCavg = Average of the 3 absolute values of the
difference between the measured HCl reference gas concentrations
with and without interference from selected stack gases (ppmv);
MCi = Measured zero or HCl reference gas concentration i
(ppmv);
MCl = Average of the measured zero or HCl reference gas
concentration i (ppmv);
MCint = Measured HCl concentration of the HCl reference
gas plus the individual or combined interference gases (ppmv);
MEextractive = Measurement error for extractive CEMS
(percent);
MEIP = Measurement error for IP-CEMS (percent);
MNavg = Average concentration at all sampling points
(ppmv);
MNbi = Measured native concentration bracketing each
calibration check measurement (ppmv);
MNi = Measured native concentration for test or run i
(ppmv);
n = Number of measurements in an average value;
PLCell = Path length of IP-CEMS calibration cell (m);
PLStack = Path length of IP-CEMS stack optical path (m);
RA = Relative accuracy of CEMS compared to a RM (percent);
RMi = RM concentration for test run i (ppmv);
RMavg = Mean measured RM value (ppmv);
S = Span of the instrument (ppmv);
Sd = Standard deviation of the differences (ppmv);
Sti = Stratification at traverse point i (percent);
SADL = Standard addition detection level (ppmv);
t0.975 = One-sided t-value at the 97.5th percentile
obtained from Table 5 in section 17.0 for n-1 measurements;
Treference = Temperature of the calibration cell for IP-
CEMS (degrees Kelvin);
Tstack = Temperature of the stack at the monitoring
location for IP-CEM (degrees Kelvin).

12.2 Calculate the Difference Between the Measured HCl
Concentration With and Without Interferents for Each Interference
Gas (Or Mixture) for Your CEMS as:
[GRAPHIC] [TIFF OMITTED] TR07JY15.068

    Calculate the total percent interference as:
    [GRAPHIC] [TIFF OMITTED] TR07JY15.069

12.3 Calculate the ME or CD at Concentration i for an Extractive
CEMS as:
[GRAPHIC] [TIFF OMITTED] TR07JY15.070

[GRAPHIC] [TIFF OMITTED] TR07JY15.071

12.4 Calculate the ME or CD at Concentration i for IP-CEMS That Use
a Calibration Cell as Follows:

    12.4.1 Calculate the equivalent concentration Ci,eff
using Equation 4:
[GRAPHIC] [TIFF OMITTED] TR07JY15.072

    12.4.2 Calculate the average native concentration before and
after each calibration check measurement as:
[GRAPHIC] [TIFF OMITTED] TR07JY15.073

    12.4.3 Calculate the ME or CD at concentration i for an IP-CEM
as:
[GRAPHIC] [TIFF OMITTED] TR07JY15.074

    12.4.4 Calculate the zero CD as a percent of span for an IP-CEMS
as:
[GRAPHIC] [TIFF OMITTED] TR07JY15.075

12.5 Calculate the Percent Stratification at Each Traverse Point
as:
[GRAPHIC] [TIFF OMITTED] TR07JY15.076

12.6 Calculate the RA Using RM and CEMS Data

    12.6.1 Determine the CEMS final integrated minute average
pollutant concentration or emission rate for each RM test period.
Consider system RT, if important, and confirm that the results have
been corrected to the same moisture, temperature and diluent
concentration basis.
    12.6.2 When Method 26A (or if approved for use, Method 26),
found in 40 CFR part 60,

appendix A-8 of this part, is used as the RM, compare each CEMS
integrated average value against the corresponding RM value for
identical test periods. Make these comparisons on the same basis
(e.g., wet, dry, ppmv, or units of the standard). To convert results
generate by Method 26A or 26 in mg/DSCM to ppmv, use the conversion
factor 0.662 ppm/(mg/DSCM).
    12.6.3 If the RM is Method 320 or Method 321, found in 40 CFR
part 63, appendix A, or ASTM D6348-12, make a direct comparison of
the average RM results and CEMS average value for identical test
periods.
    12.6.4 For each test run, calculate the arithmetic difference of
the RM and CEMS results using Equation 9.
[GRAPHIC] [TIFF OMITTED] TR07JY15.077

    12.6.5 Calculate the standard deviation of the differences (Sd)
of the CEMS measured and RM results using Equation 10.
[GRAPHIC] [TIFF OMITTED] TR07JY15.078

    12.6.6 Calculate the confidence coefficient (CC) for the RATA
using Equation 11.
[GRAPHIC] [TIFF OMITTED] TR07JY15.079

    12.6.7 Calculate the mean difference (davg) between the RM and
CEMS values in the units of ppmv or the emission standard using
Equation 12.
[GRAPHIC] [TIFF OMITTED] TR07JY15.080

    12.6.8 Calculate the average RM value using Equation 13.
    [GRAPHIC] [TIFF OMITTED] TR07JY15.081

    12.6.9 Calculate RA of the CEMS using Equation 14.
    [GRAPHIC] [TIFF OMITTED] TR07JY15.082

13.0 Method Performance

    13.1 Level of Detection. You may not use a CEMS whose LOD or
SADL is greater than 20 percent of the applicable regulatory limit
or other action level for the intended use of the data.
    13.2 Calibration Drift. The zero- and mid-level calibration
drift for the CEMS must not exceed 5.0 percent of the span value for
7 consecutive operating days.
    13.3 Measurement Error. The ME must be less than or equal to 5.0
percent of the span value at the low-, mid-, and high-level
reference gas concentrations.
    13.4 Relative Accuracy. Unless otherwise specified in an
applicable regulation or permit, the RA of the CEMS, whether
calculated in units of HCl concentration or in units of the emission
standard, must be less than or equal to 20.0 percent of the RM when
RMavg is used in the denominator of Equation 14.
    13.4.1 In cases where the RA is calculated on a concentration
(ppmv) basis, if the average RM emission level for the test is less
than 75 percent of the HCl concentration equivalent to the emission
standard, you may substitute the HCl concentration equivalent to the
standard in the denominator of Equation 14 in place of RMavg.
    13.4.2 Similarly, if the RA is calculated in units of the
emission standard and the HCl emission level measured by the RMs is
less than 75 percent of the emission standard, you may substitute
the emission standard in the denominator of Equation 14 in place of
RMavg.
    13.4.3 The alternative calculated RA in paragraph 13.4.1 or
13.4.2 must be less than or equal to 15.0 percent.
    13.5 Interference Test.
    13.5.1 The sum of the interference response(s) from Equation 2
must not be greater than 2.5 percent of the calibration span or
3.0 percent of the equivalent HCl concentration used for
the interference test, whichever is less restrictive. The results
are also acceptable if the sum of the interference response(s) does
not exceed six times the LOD or 0.5 ppmv for a calibration span of 5
to 10 ppm, or 0.2 ppmv for a calibration span of less than 5 ppmv.
    13.6 IP-CEMS Beam Intensity Test. For IP-CEMS, the percent
difference between the measured concentration with and without
attenuation of the light source must not exceed 3.0
percent.
    13.7 IP-CEMS Temperature Measurement Verification. Your
temperature sensor satisfies the accuracy required if the absolute
relative difference between measured value of stack temperature
(Mt) and the temperature

value from the calibrated temperature reference device
(Vt) is <=1.0 percent or if the absolute difference
between Mt and Vt is <=2.8[deg] C (5.0
[deg]F), whichever is less restrictive.
    13.8 IP-CEMS Pressure Sensor Measurement Verification. Your
pressure sensor satisfies the accuracy required if the absolute
relative difference between the measured value of stack pressure
(MP) and the pressure value from the calibrated pressure
reference device (VP) is <=5.0 percent or if the absolute
difference between Mp and VP is <=0.12
kilopascals (0.5 inches of water column), whichever is less
restrictive.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 Bibliography

    1. Method 318--Extractive FTIR Method for the Measurement of
Emissions From the Mineral Wool and Wool Fiberglass Industries, 40
CFR, part 63, subpart HHHHHHH, appendix A.
    2. ``EPA Protocol for the Use of Extractive Fourier Transform
Infrared (FTIR) Spectrometry in Analyses of Gaseous Emissions from
Stationary Industrial Sources,'' February, 1995.
    3. ``Measurement of Gaseous Organic and Inorganic Emissions by
Extractive FTIR Spectroscopy,'' EPA Contract No. 68-D2-0165, Work
Assignment 3-08.
    4. ``Method 301--Field Validation of Pollutant Measurement
Methods from Various Waste Media,'' 40 CFR part 63, appendix A.
    5. EPA Traceability Protocol for Assay and Certification of
Gaseous Calibration Standards, U.S. Environmental Protection Agency
office of Research and Development, EPA/600/R-12/531, May 2012.

17.0 Tables, Diagrams, Flowcharts, and Validation Data

              Table 1--Interference Test Gas Concentrations
------------------------------------------------------------------------
                                     Approximate concentration (balance
    Potential interferent gas 1                      N2)
------------------------------------------------------------------------
CO2...............................  15%  1% CO2.2
CO................................  100  20 ppm.
CH2O..............................  20  5 ppm.
CH4...............................  100  20 ppm.
NH3...............................  10  5 ppm (extractive
                                     CEMS only).
NO2...............................  250  50 ppm.
SO2...............................  200  20 ppm.
O2................................  3%  1% O2.2
H2O...............................  10%  1% H2O.2
N2................................  Balance.2
------------------------------------------------------------------------
\1\ Any of these specific gases can be tested at a lower level if the
  manufacturer has provided reliable means for limiting or scrubbing
  that gas to a specified level in CEMS field installations.
\2\ Gases for short path IP cell interference tests cannot be added
  above 100 percent stack equivalent concentration. Add these gases at
  the indicated percentages to make up the remaining cell volume.

BILLING CODE P

[GRAPHIC] [TIFF OMITTED] TR07JY15.083

BILLING CODE C

            Table 3--Design Standards for Temperature Sensors
------------------------------------------------------------------------
                                    You can use the following design
   If the sensor is a . . .       standards as guidance in selecting a
                                        sensor for your IP-CEMS
------------------------------------------------------------------------
1. Thermocouple..............  a. ASTM E235-88 (1996), ``Specification
                                for Thermocouples, Sheathed, Type K, for
                                Nuclear or Other High-Reliability
                                Applications.''
                               b. ASTM E585/E585M-04, ``Specification
                                for Compacted Mineral-Insulated, Metal-
                                Sheathed, Base Metal Thermocouple
                                Cable.''
                               c. ASTM E608/E608M-06, ``Specification
                                for Mineral-Insulated, Metal-Sheathed
                                Base Metal Thermocouples.''
                               d. ASTM E696-07, ``Specification for
                                Tungsten-Rhenium Alloy Thermocouple
                                Wire.''
                               e. ASTM E1129/E1129M-98 (2002),
                                ``Standard Specification for
                                Thermocouple Connectors.''
                               f. ASTM E1159-98 (2003), ``Specification
                                for Thermocouple Materials, Platinum-
                                Rhodium Alloys, and Platinum.''
                               g. ISA-MC96.1-1982, ``Temperature
                                Measurement Thermocouples.''
2. Resistance temperature      ASTM E1137/E1137M-04, ``Standard
 detector.                      Specification for Industrial Platinum
                                Resistance Thermometers.''
------------------------------------------------------------------------

                                          Table 4--Performance Specification Test Zero and Reference Gas Ranges
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                           HCl Zero and Reference Gas Concentrations in Terms of Percent of
                                                                                Span \a\
                   Test                                Units             -------------------------------------------------------------------   Section
                                                                                Zero              Low Level    Mid Level    High Level
--------------------------------------------------------------------------------------------------------------------------------------------------------
Calibration Drift........................  % of Span....................   2.0 percent or calculate the flow using a stable
tracer gas included in your spike gas standard.
    <IP_ADDRESS> If you use flow measurements to determine the spike
dilution, then use Equation A1 in section 11.2.1 of this appendix to
calculate the DF. Determination of the spike dilution requires
measurement of HCl spike flow (Qspike) and total flow
through the CEM sampling system (Qprobe).
    <IP_ADDRESS> If your CEMS is capable of measuring an independent
stable tracer gas, you may use a spike gas that includes the tracer
to determine the DF using Equation A2 or A3 (sections 11.2.2 and
11.2.3 of this appendix) depending on whether the tracer gas is also
present in the native source emissions.
    <IP_ADDRESS> For extractive CEMS, you must correct the background
measurements of HCl for the dilution caused by the addition of the
spike gas standard. For spiking systems that alternate between
addition of HCl and zero gas at a constant DF, the background
measurements between spikes will not be equal to the native source
concentration.
    8.2.5 Begin by collecting unspiked sample measurements of HCl.
You must use the average of two unspiked sample measurements as your
pre-spike background.
    Note: Measurements should agree within 5.0 percent or three
times the level of detection to avoid biasing the spike results.
    <IP_ADDRESS> Introduce the HCl gas spike into the permanent CEMS
probe, upstream of the particulate filter or sample conditioning
system and as close to the sampling inlet as practical.
    <IP_ADDRESS> Maintain the HCl gas spike for at least twice the DS
response time of your CEMS or until the consecutive measurements
agree within 5.0 percent. Collect two

independent measurements of the native plus spiked HCl
concentration.
    <IP_ADDRESS> Stop the flow of spike gas for at least twice the DS
response time of your CEMS or until the consecutive measurements
agree within 5.0 percent. Collect two independent measurements of
the native HCl concentration.
    8.2.6 Repeat the collection of sample measurements in section
8.2.5 until you have data for each spike concentration including a
final set of unspiked sample measurements according to section
<IP_ADDRESS>.
    8.2.7 Verify that the CEMS responded as expected for each spike
gas injection, and that the data quality is not impacted by large
shifts in the native source concentration. Discard and repeat any
spike injections as necessary to generate a complete set of the
required replicate spike measurements.
    8.2.8 Calculate the standard addition response (SAR) for
extractive CEMS, using Equation A4 in section 11.2, of this
appendix.
    8.2.9 If the DS results do not meet the specifications for the
appropriate performance test in PS-18 or Procedure 6 of appendix F
of this part, you must take corrective action and repeat the DS
procedure.
    8.3 SA Procedure for IP-CEMS (Static Spiking).
    8.3.1 For IP-CEMS, you must make measurements of native source
gas HCl concentration and an HCl standard addition using a
calibration cell added to the optical measurement path.
    8.3.2 Introduce zero gas into a calibration cell located in the
optical measurement path of the instrument. Continue to flush the
zero gas into the cell for at least the SA response time of your
CEMS or until two consecutive measurements taken are within 5.0
percent, then collect two independent measurements. Alternatively
you may measure native concentrations without the calibration cell
in the optical path.
    8.3.3 Introduce the HCl spike gas into the calibration cell.
Continue to flush the spike gas into the cell for at least the SA
response time of your CEMS or until two consecutive measurements
taken are within 5.0 percent of one another. Then collect two
independent measurements of the SA addition to the native
concentration. Alternatively you may insert a sealed calibration
cell, containing HCl at the appropriate concentration, into the
optical path to measure the SA addition to the native concentration.
    8.3.4 Repeat the collection of SA-elevated and native HCl
measurements in sections 8.3.2 and 8.3.3 until you have data for
each SA concentration. Then, make a final native HCl measurement.
The measured concentrations must be corrected for calibration cell
and stack temperature, pressure and stack measurement path length.
    8.3.5 Calculate the standard addition response (SAR) for an IP-
CEMS, using Equation A8 in section 11.3 of this appendix.
    8.3.6 If the SA results do not meet the specifications for the
appropriate performance test in PS-18 or Procedure 6 of appendix F
of this part, you must take corrective action and repeat the SA
procedure.

9.0 Quality Control [Reserved]

10.0 Calibration and Standardization [Reserved]

    11.0 Calculations and Data Analysis. Calculate the SA response
for each measurement and its associated native HCl measurement(s),
using equations in this section. (Note: For cases where the emission
standard is expressed in units of lb/MMBtu or corrected to a
specified O2 or CO2 concentration, an absolute
accuracy specification based on a span at stack conditions may be
calculated using the average concentration and applicable conversion
factors. The appropriate procedures for use in cases where a percent
removal standard is more restrictive than the emission standard are
the same as in 40 CFR part 60, PS-2, sections 12 and 13.)
    11.1 Nomenclature.

Cspike = Actual HCl reference gas concentration spiked
(e.g., bottle or reference gas concentration) ppmv;
Ctracer spiked = Tracer gas concentration injected with
spike gas (``reference concentration'') ppmv;
DF = Spiked gas dilution factor;
DSCD = Calibration drift determined using DS procedure (percent);
DSE = Dynamic spike error (ppmv);
ESA = Effective spike addition (ppmv);
MCSA = Measured SA-elevated source gas concentration
(ppmv);
MCspiked = Measured HCl reference gas concentration i
(ppmv);
MCnative = Average measured concentration of the native
HCl (ppmv);
Mnative tracer = Measured tracer gas concentration
present in native effluent gas (ppmv);
Mspiked tracer = Measured diluted tracer gas
concentration in a spiked sample (ppmv);
Qspike = Flow rate of the dynamic spike gas (Lpm);
Qprobe = Average total stack sample flow through the
system (Lpm);
S = Span (ppmv);
SAR = Standard addition response (ppmv)

    11.2 Calculating Dynamic Spike Response and Error for Extractive
CEMS.
    11.2.1 If you determine your spike DF using spike gas and stack
sample flow measurements, calculate the DF using equation A1:
[GRAPHIC] [TIFF OMITTED] TR07JY15.087

    11.2.2 If you determine your spike DF using an independent
stable tracer gas that is not present in the native source
emissions, calculate the DF for DS using equation A2:
[GRAPHIC] [TIFF OMITTED] TR07JY15.088

    11.2.3 If you determine your spike dilution factor using an
independent stable tracer that is present in the native source
emissions, calculate the dilution factor for dynamic spiking using
equation A3:
[GRAPHIC] [TIFF OMITTED] TR07JY15.089

    11.2.4 Calculate the SA response using Equation A4:
    [GRAPHIC] [TIFF OMITTED] TR07JY15.090

    11.2.5 Calculate the DS error using Equation A5.
    [GRAPHIC] [TIFF OMITTED] TR07JY15.091

    11.2.6 Calculating CD using DS. When using the DS option for
determining mid-level CD, calculate the CD as a percent of span
using equation A6:
[GRAPHIC] [TIFF OMITTED] TR07JY15.092

    11.2.7 The effective spike addition (ESA) is the expected
increase in the measured concentration as a result of injecting a
spike. Calculate ESA using Equation A7:
[GRAPHIC] [TIFF OMITTED] TR07JY15.093

    11.3 Standard Addition Response for IP-CEMS. If you use an IP-
CEMS and a calibration cell, calculate the SA response using
Equation A8.
[GRAPHIC] [TIFF OMITTED] TR07JY15.094

13. Tables and Figures.

[GRAPHIC] [TIFF OMITTED] TR07JY15.095

0
3. Appendix F to part 60 is amended by adding Procedure 6 to read as
follows:

Appendix F to Part 60--Quality Assurance Procedures

* * * * *
    Procedure 6. Quality Assurance Requirements for Gaseous Hydrogen
Chloride (HCl) Continuous Emission Monitoring Systems Used for
Compliance Determination at Stationary Sources

1.0 Applicability and Principle

    1.1 Applicability. Procedure 6 is used to evaluate the
effectiveness of quality control (QC) and quality assurance (QA)
procedures and evaluate the quality of data produced by any hydrogen
chloride (HCl) gas, CAS: 7647-01-0, continuous emission monitoring
system (CEMS) that is used for determining compliance with emission
standards for HCl on a continuous basis as specified in an
applicable permit or regulation.
    1.1.1 This procedure specifies the minimum QA requirements
necessary for the control and assessment of the quality of CEMS data
submitted to the Environmental Protection Agency (EPA) or a
delegated authority. If you are responsible for one or more CEMS
used for HCl compliance monitoring you must meet these minimum
requirements and you are encouraged to develop and implement a more
extensive QA program or to continue such programs where they already
exist.
    1.1.2 Data collected as a result of QA and QC measures required
in this procedure are to be submitted to the EPA or the delegated
authority in accordance with the applicable regulation or permit.
These data are to be used by both the delegated authority and you,
as the CEMS operator, in assessing the effectiveness of the CEMS QC
and QA procedures in the maintenance of acceptable CEMS operation
and valid emission data.

1.2 Principle

    1.2.1 The QA procedures consist of two distinct and equally
important functions. One function is the assessment of the quality
of the CEMS data by estimating accuracy. The other function is the
control and improvement of the quality of the CEMS data by
implementing QC policies and corrective actions. These two functions
form an iterative control loop. When the assessment function
indicates that the data quality is inadequate, the control effort
must be increased until the data quality is acceptable. In order to
provide uniformity in the assessment and reporting of data quality,
this procedure specifies the assessment procedures to evaluate
response drift and accuracy. The procedures specified are based on
Performance Specification 18 (PS-18) in appendix B to this part.
    (Note: Because the control and corrective action function
encompasses a variety of policies, specifications, standards and
corrective measures, this procedure treats QC requirements in
general terms to allow you, as source owner or operator to develop
the most effective and efficient QC system for your circumstances.)

2.0 Definitions

    See PS-18 of this subpart for the primary definitions used in
this Procedure.

3.0 QC Requirements

    3.1 You, as a source owner or operator, must develop and
implement a QC program. At a minimum, each QC program must include
written procedures and/or manufacturer's information which should
describe in detail, complete, step-by-step procedures and operations
for each of the following activities:
    (a) Calibration Drift (CD) checks of CEMS;
    (b) CD determination and adjustment of CEMS;
    (c) Integrated Path (IP) CEMS temperature and pressure sensor
accuracy checks;
    (d) IP CEMS beam intensity checks;

    (e) Routine and preventative maintenance of CEMS (including
spare parts inventory);
    (f) Data recording, calculations, and reporting;
    (g) Accuracy audit procedures for CEMS including reference
method(s); and
    (h) Program of corrective action for malfunctioning CEMS.
    3.2 These written procedures must be kept on site and available
for inspection by the delegated authority. As described in section
5.4, whenever excessive inaccuracies occur for two consecutive
quarters, you must revise the current written procedures, or modify
or replace the CEMS to correct the deficiency causing the excessive
inaccuracies.

4.0 Daily Data Quality Requirements and Measurement Standardization
Procedures

    4.1 CD Assessment. An upscale gas, used to meet a requirement in
this section must be either a NIST-traceable reference gas or a gas
certified by the gas vendor to 5.0 percent accuracy.
    4.1.1 CD Requirement. Consistent with 40 CFR 60.13(d) and
63.8(c), you, as source owners or operators of CEMS must check,
record, and quantify the CD at two levels, using a zero gas and mid-
level gas at least once daily (approximately every 24 hours).
Perform the CD check in accordance with the procedure in applicable
performance specification (e.g., section 11.8 of PS-18 in appendix B
of this part). The daily zero- and mid-level CD must not exceed two
times the drift limits specified in the applicable performance
specification (e.g., section 13.2 of PS-18 in appendix B to this
part.)
    4.1.2 Recording Requirement for CD Corrective action. Corrective
actions taken to bring a CEMS back in control after exceeding a CD
limit must be recorded and reported with the associated CEMS data.
Reporting corrective action must include the unadjusted
concentration measured prior to resetting the calibration and the
adjusted value after resetting the calibration to bring the CEMS
back into control.
    4.1.3 Dynamic Spiking Option for Mid-level CD. For extractive
CEMS, you have the option to conduct a daily dynamic spiking
procedure found in section 11.8.8 of PS-18 of appendix B of this
part in lieu of the daily mid-level CD check. If this option is
selected, the daily zero CD check is still required.
    4.1.4 Out of Control Criteria for Excessive CD. As specified in
Sec.  63.8(c)(7)(i)(A), a CEMS is out of control if the zero or mid-
level CD exceeds two times the applicable CD specification in the
applicable PS or in the relevant standard. When a CEMS is out of
control, you as owner or operator of the affected source must take
the necessary corrective actions and repeat the tests that caused
the system to go out of control (in this case, the failed CD check)
until the applicable performance requirements are met.
    4.1.5 Additional Quality Assurance for Data above Span. This
procedure must be used when required by an applicable regulation and
may be used when significant data above span is being collected.
    <IP_ADDRESS> Any time the average measured concentration of HCl
exceeds 150 percent of the span value for greater than two hours,
conduct the following `above span' CEMS response check.
    <IP_ADDRESS>.1 Within a period of 24 hours (before or after) of the
`above span' period, introduce a higher, `above span' HCl reference
gas standard to the CEMS. Use `above span' reference gas that meets
the requirements of section 7.0 of PS-18 and target a concentration
level between 75 and 125 percent of the highest hourly concentration
measured during the period of measurements above span.
    <IP_ADDRESS>.2 Introduce the reference gas at the probe for
extractive CEMS or for IP-CEMS as an equivalent path length
corrected concentration in the instrument calibration cell.
    <IP_ADDRESS>.3 At no time may the `above span' concentration exceed
the analyzer full-scale range.
    <IP_ADDRESS> Record and report the results of this procedure as you
would for a daily calibration. The `above span' response check is
successful if the value measured by the CEMS is within 20 percent of
the certified value of the reference gas.
    <IP_ADDRESS> If the `above span' response check is conducted during
the period when measured emissions are above span and there is a
failure to collect at least one data point in an hour due to the
response check duration, then determine the emissions average for
that missed hour as the average of hourly averages for the hour
preceding the missed hour and the hour following the missed hour.
    <IP_ADDRESS> In the event that the `above span' response check is not
successful (i.e., the CEMS measured value is not within 20 percent
of the certified value of the reference gas), then you must
normalize the one-hour average stack gas values measured above the
span during the 24-hour period preceding or following the `above
span' response check for reporting based on the CEMS response to the
reference gas as shown in Eq. 6-1:
[GRAPHIC] [TIFF OMITTED] TR07JY15.096

4.2 Beam Intensity Requirement for HCl IP-CEMS.

    4.2.1 Beam Intensity Measurement. If you use a HCl IP-CEMS, you
must quantify and record the beam intensity of the IP-CEMS in
appropriate units at least once daily (approximately 24 hours apart)
according to manufacturer's specifications and procedures.
    4.2.2 Out of Control Criteria for Excessive Beam Intensity Loss.
If the beam intensity falls below the level established for the
operation range determined following the procedures in section 11.2
of PS-18 of this part, then your CEMS is out-of-control. This
quality check is independent of whether the CEMS daily CD is
acceptable. If your CEMS is out-of-control, take necessary
corrective action. You have the option to repeat the beam intensity
test procedures in section 11.2 of PS-18 to expand the acceptable
range of acceptable beam intensity. Following corrective action,
repeat the beam intensity check.
    4.3 Out Of Control Period Duration for Daily Assessments. The
beginning of the out-of-control period is the hour in which the
owner or operator conducts a daily performance check (e.g.,
calibration drift or beam intensity check) that indicates an
exceedance of the performance requirements established under this
procedure. The end of the out-of-control period is the completion of
daily assessment of the same type following corrective actions,
which shows that the applicable performance requirements have been
met.
    4.4 CEMS Data Status During Out-of-Control Period. During the
period the CEMS is out-of-control, the CEMS data may not be used in
calculating compliance with an emissions limit nor be counted
towards meeting minimum data availability as required and described
in the applicable regulation or permit.

5.0 Data Accuracy Assessment

    You must audit your CEMS for the accuracy of HCl measurement on
a regular basis at the frequency described in this section, unless
otherwise specified in an applicable regulation or permit. Quarterly
audits are performed at least once each calendar quarter. Successive
quarterly audits, to the extent practicable, shall occur no closer
than 2 months apart. Annual audits are performed at least once every
four consecutive calendar quarters.

5.1 Temperature and Pressure Accuracy Assessment for IP CEMS.

    5.1.1 Stack or source gas temperature measurement audits for HCl
IP-CEMS must be conducted and recorded at least annually in
accordance with the procedure described in section 11.3 of PS-18 in
appendix B to this part. As an alternative, temperature measurement
devices may be replaced with certified instruments on an annual
basis. Units removed from service may be bench tested against an
NIST traceable sensor and reused during subsequent years. Any
measurement instrument or device that is used to conduct ongoing
verification of

temperature measurement must have an accuracy that is traceable to
NIST.
    5.1.2 Stack or source gas pressure measurement audits for HCl
IP-CEMS must be conducted and recorded at least annually in
accordance with the procedure described in section 11.4 of PS-18 in
appendix B of this part. As an alternative, pressure measurement
devices may be replaced with certified instruments on an annual
basis. Units removed from service may be bench tested against an
NIST traceable sensor and reused during subsequent years. Any
measurement instrument or device that is used to conduct ongoing
verification of pressure measurement must have an accuracy that is
traceable to NIST.
    5.1.3 Out of Control Criteria for Excessive Parameter
Verification Inaccuracy. If the temperature or pressure verification
audit exceeds the criteria in sections <IP_ADDRESS> and <IP_ADDRESS>,
respectively, the CEMS is out-of-control. If the CEMS is out-of-
control, take necessary corrective action to eliminate the problem.
Following corrective action, you must repeat the failed verification
audit until the temperature or pressure measurement device is
operating within the applicable specifications, at which point the
out-of-control period ends.
    5.2 Concentration Accuracy Auditing Requirements. Unless
otherwise specified in an applicable rule or permit, you must audit
the HCl measurement accuracy of each CEMS at least once each
calendar quarter, except in the case where the affected facility is
off-line (does not operate). In that case, the audit must be
performed as soon as is practicable in the quarter in which the unit
recommences operation. Successive quarterly audits must, to the
extent practicable, be performed no less than 2 months apart. The
accuracy audits shall be conducted as follows:
    5.2.1 Relative Accuracy Test Audit. A RATA must be conducted at
least once every four calendar quarters, except as otherwise noted
in sections 5.2.5 or 5.5 of this procedure. Perform the RATA as
described in section 11.9 of PS-18 in appendix B to this part. If
the HCl concentration measured by the RM during a RATA (in ppmv) is
less than or equal to 20 percent of the concentration equivalent to
the applicable emission standard, you must perform a Cylinder Gas
Audit (CGA) or a Dynamic Spike Audit (DSA) for at least one
subsequent (one of the following three) quarterly accuracy audits.
    5.2.2 Quarterly Relative Accuracy Audit (RAA). A quarterly RAA
may be conducted as an option to conducting a RATA in three of four
calendar quarters, but in no more than three quarters in succession.
To conduct an RAA, follow the test procedures in section 11.9 of PS-
18 in appendix B to this part, except that only three test runs are
required. The difference between the mean of the RM values and the
mean of the CEMS responses relative to the mean of the RM values (or
alternatively the emission standard) is used to assess the accuracy
of the CEMS. Calculate the RAA results as described in section 6.2.
As an alternative to an RAA, a cylinder gas audit or a dynamic
spiking audit may be conducted.
    5.2.3 Cylinder Gas Audit. A quarterly CGA may be conducted as an
option to conducting a RATA in three of four calendar quarters, but