CLEAN AIR ACT
NATIONAL STACK TESTING GUIDANCE
April 27, 2009
Any questions concerning this guidance may be directed to either Mamie Miller at
(202) 564-2300 or Rob Lischinsky at (202) 564-2628.
CLEAN AIR ACT
NATIONAL STACK TESTING GUIDANCE
INTRODUCTION
• A stack test, also referred to in EPA regulations as a performance or source test, measures the
amount of a specific regulated pollutant, pollutants, or surrogates being emitted; demonstrates
the capture efficiency of a capture system; or determines the destruction or removal efficiency of
a control device used to reduce emissions at facilities subject to the requirements of the Clean
Air Act (CAA or Act). Stack testing is an important tool used to determine a facility’s
compliance with emission limits, or capture or control efficiencies established pursuant to the
CAA. This tool has not always been consistently applied or utilized across the country by the
U.S. Environmental Protection Agency (EPA or Agency), or delegated state/local agencies. This
guidance is intended to address stack tests performed to determine both initial and on-going
compliance with the CAA requirements.
• A review by the EPA Office of the Inspector General (IG) ("Report of EPA’s Oversight of
Stack Testing Programs," 2000-P-00019, September 11, 2000) criticized EPA for not issuing
comprehensive national guidance in this area, and not providing sufficient oversight of
state/local stack testing programs. The IG concluded that this lack of guidance and oversight had
an adverse effect on the use of stack testing as a tool in determining compliance. As a result of
the findings, the IG recommended that EPA develop national guidance that addresses issues such
as:
-recommended testing frequencies;
-discrepancies in test procedures; and
-inconsistent reporting of test results.
• In addition to national guidance, the IG recommended that EPA enhance its oversight
program.
• In response to the IG report, the Office of Enforcement and Compliance Assurance (OECA)
made a commitment to address the concerns raised in the report and provide clarification, as
necessary, on the issues identified. The Office of Compliance (OC) was given the responsibility
for satisfying this commitment.
• The concerns associated with testing frequencies, and the reporting of test results were
addressed in the CAA Stationary Source Compliance Monitoring Strategy (CMS) issued by the
Agency in April 2001. The Timely And Appropriate Enforcement Response To High Priority
Violations Policy (HPV Policy) issued by the Agency in December 1998 provides
supplementary guidance by specifying how violations identified through stack testing should be
addressed. Each of these documents is summarized below for the reader’s convenience;
however, for a more thorough understanding of these policies, we suggest that the reader review
Page 2
the documents in their entirety.
-An electronic version of CMS can be obtained at:
www.epa.gov/compliance/resources/policies/monitoring/cmspolicy.pdf.
-The HPV Policy can be obtained at:
www.epa.gov/compliance/resources/policies/civil/caa/stationary/issue-ta-rpt.pdf.
-The website for the associated HPV Workbook is:
www.epa.gov/compliance/resources/policies/civil/caa/stationary/hpvmanualrevised.pdf.
• This stack testing guidance was developed to address the remaining issues raised by the IG,
specifically those associated with the conduct of stack tests. A Workgroup with representatives
from OECA, the Office of Air Quality Planning and Standards (OAQPS), and the EPA Regions
was formed to develop the guidance. In formulating this guidance, the Workgroup reviewed all
relevant Agency guidance and applicability determinations; evaluated all identified state
regulations and guidance on stack testing; and solicited state/local input in various forums.
• The discussion in this document is intended solely as guidance. This guidance is not a
regulation, nor is it intended to change any underlying regulatory requirements specified in
individual New Source Performance Standards (NSPS), National Emission Standards for
Hazardous Air Pollutants (NESHAP), NESHAP for Source Categories (MACT), state or local
regulations. This guidance merely documents and clarifies existing regulatory requirements and
Agency guidance on stack testing.
• It is not our practice to distribute guidance such as this for formal public notice and comment
as it does not supersede or alter existing regulatory requirements, nor impose any new legally
binding requirements on EPA, state/local agencies, or the regulated community. The general
description provided in this document may not apply to a particular situation based on the
circumstances. Furthermore, interested parties remain free to raise questions or objections about
the substance and application of the guidance as they arise in a particular situation. EPA retains
the discretion to adopt approaches on a case-by-case basis that differ from those described in this
guidance where appropriate. This document may be revised periodically without public notice.
• On February 2, 2004, EPA issued the stack testing guidance as interim to provide an
opportunity to evaluate its usage and monitor any potential problems with its implementation.
During the interim period, EPA received feedback from individual state/local agencies,
state/local air associations, and industry associations and representatives.
• On September 30, 2005, after reviewing all comments received on the interim guidance and
addressing such comments as appropriate, EPA issued final guidance. The final guidance
superceded the February 2, 2004 interim guidance. At the time of issuance of the final guidance,
EPA noted that the Agency would conduct notice and comment rulemaking regarding the
appropriate circumstances in which an extension of performance test deadlines may be allowed
by regulation.
Page 3
• On August 9, 2006, EPA published in the Federal Register (FR) proposed amendments to the
General Provisions for the NSPS, NESHAP, and MACT programs to allow source owners or
operators, in the event of a force majeure, to petition the Administrator for an extension of the
deadline(s) by which they are required to conduct an initial or subsequent performance test
required by applicable regulations.
• The proposed revisions to the NSPS, NESHAP, and MACT General Provisions became
effective on May 16, 2007. The revisions were extended to the Consolidated Federal Air Rule
(CFAR) (40 CFR Part 65) on August 27, 2007.
• This guidance dated April 27, 2009, supersedes the September 30, 2005, guidance. It
incorporates the amendments to the General Provisions and the CFAR which allow source
owners or operators to petition for an extension to the test deadlines as a result of a force majeure
event. It also includes other minor clarifications and revisions based on feedback EPA has
received since issuance of the guidance in 2005.
II GOALS OF THE NATIONAL STACK TESTING GUIDANCE
• Expand upon CMS and the HPV Policy to fully address the concerns raised by the IG on this
issue.
• Improve uniformity on how stack tests are conducted for determining and demonstrating
compliance with the NSPS (40 CFR Part 60), NESHAP (40 CFR Part 61), and MACT (40 CFR
Part 63).
• Improve coordination between EPA and state/local agencies.
• Enhance EPA oversight of state/local programs to ensure that the tool of stack testing is being
sufficiently and properly utilized.
III DEFINITION OF STACK TESTING
• Stack testing may be conducted for varying purposes, such as relative accuracy test audits
(RATAs), linearity checks, and routine calibration of continuous emission monitoring (CEM)
equipment. However, for purposes of this guidance, stack testing is being more narrowly
defined as:
-Any performance testing conducted for the purposes of determining and demonstrating
compliance with the applicable standards of 40 CFR Parts 60, 61, and 63 using
promulgated test methods, other test methods or procedures cited in the applicable
subpart(s), or alternative test methods approved by the Administrator under §§ 60.8,
61.13, or 63.7. It does not include visible emission observation testing.
Page 4
IV SCOPE OF GUIDANCE
• The guidance applies to tests conducted for the purposes of determining and demonstrating
compliance with NSPS, NESHAP, and MACT programs. The guidance does not apply to tests
in situations such as the following:
- tests requested by EPA to assist the Agency in the development of regulations or
emissions factors;
- tests to establish monitoring protocols for parametric monitoring under the Compliance
Assurance Monitoring requirements of 40 CFR Part 64;
- tests to develop and evaluate alternative test methods;
- tests voluntarily conducted by facilities for their own purposes to optimize operations
and improve energy efficiency;
- tests conducted only to determine and demonstrate compliance with state
Implementation Plan (SIP) requirements. (Tests conducted to simultaneously determine
and demonstrate compliance with NSPS, NESHAP, and MACT programs are included
within the scope of the guidance.)
• The data from tests conducted in situations such as those listed above may be subject to Title
V reporting requirements and need to be considered by the source when submitting reports and
certifying compliance pursuant to the Title V program.
CAA STATIONARY SOURCE COMPLIANCE MONITORING STRATEGY
• The CMS provides guidance on stationary source air compliance monitoring programs with a
focus on Title V major sources and synthetic minor sources that emit or have the potential to
emit at or above 80 percent of the Title V major threshold. It addresses the IG issues of when a
stack test should be conducted and what information should be reported nationally. It recognizes
that consistent, complete and accurate stack test information is critical in managing a national air
program. Hence, the CMS recommends:
-States/locals should conduct a stack test where there is no other means for determining
compliance with the emission limits. In determining whether a stack test is necessary,
states/locals should consider factors such as: size of emission unit; time elapsed since last
stack test; results of that test and margin of compliance; condition of control equipment;
and availability and results of associated monitoring data.
-States/locals should conduct a stack test whenever they deem appropriate regardless of
Page 5
whether there are other means for determining compliance.
-The date and results (Pass/Fail/Pending) of all stack tests should be entered in the
national air data system (AIRS/AFS, or its successor), and the High Priority Violations
(HPV) status adjusted as appropriate.
VI HIGH PRIORITY VIOLATIONS POLICY
• The HPV Policy provides guidance on how to define significant violations under the CAA at
major stationary sources, and the timely and appropriate enforcement response when such
violations are identified. It addresses the IG concern with consistent treatment of stack test
failures.
• Facilities are to be in compliance with applicable requirements at all times except during
periods of startup, shutdown or malfunction, or under circumstances as defined in the underlying
NSPS, NESHAP, or MACT standards or General Provisions to 40 CFR Parts 60 and 63.1 All
stack test failures should be reviewed by the delegated agency to determine whether a violation
has occurred, and if so, the appropriate enforcement response. The enforcement response should
be consistent with the HPV Policy which states:
"The following criteria trigger HPV status. . . Violations that involve testing, monitoring,
recordkeeping or reporting that substantially interfere with enforcement or determining
the source’s compliance with applicable emission limits. . . A violation of an allowable
emission limit detected during a reference method stack test." See HPV Policy, pp. 3-4.
See also HPV Workbook, p. 3.5.
• Violations of emission limits for pollutants for which a facility is not designated as a "major "
source may not rise to the level of HPV. The guidance addresses such circumstances by stating:
"EPA expects that all violations of air pollution regulations, whether meeting the HPV
criteria or not, will be addressed by states, local agencies, or EPA." See HPV
Policy, p. 2.
• The HPV Policy does not apply in situations where the delegated agency accepts a facility’s
claim that it was unable to conduct an initial performance test within the regulatory deadline due
to a Force Majeure Event. A more detailed discussion of such an event is described below in the
Section, "The Time Frame for Conducting Stack Tests."
1 The Agency has issued separate guidance for SIPs on how to address excess emissions
during start-up, shutdown or malfunctions.
Page 6
VII MAJOR ISSUES
• The guidance addresses the following major issues:
1. The Time Frame for Conducting Stack Tests
2. Stack Test Waivers
3. Stack Test Notifications
4. Observation of Stack Tests
5. Representative Testing Conditions
6. Stoppages
7. Postponements
8. Test Reports
NATIONAL STACK TESTING GUIDANCE
April 27, 2009
Any questions concerning this guidance may be directed to either Mamie Miller at
(202) 564-2300 or Rob Lischinsky at (202) 564-2628.
CLEAN AIR ACT
NATIONAL STACK TESTING GUIDANCE
INTRODUCTION
• A stack test, also referred to in EPA regulations as a performance or source test, measures the
amount of a specific regulated pollutant, pollutants, or surrogates being emitted; demonstrates
the capture efficiency of a capture system; or determines the destruction or removal efficiency of
a control device used to reduce emissions at facilities subject to the requirements of the Clean
Air Act (CAA or Act). Stack testing is an important tool used to determine a facility’s
compliance with emission limits, or capture or control efficiencies established pursuant to the
CAA. This tool has not always been consistently applied or utilized across the country by the
U.S. Environmental Protection Agency (EPA or Agency), or delegated state/local agencies. This
guidance is intended to address stack tests performed to determine both initial and on-going
compliance with the CAA requirements.
• A review by the EPA Office of the Inspector General (IG) ("Report of EPA’s Oversight of
Stack Testing Programs," 2000-P-00019, September 11, 2000) criticized EPA for not issuing
comprehensive national guidance in this area, and not providing sufficient oversight of
state/local stack testing programs. The IG concluded that this lack of guidance and oversight had
an adverse effect on the use of stack testing as a tool in determining compliance. As a result of
the findings, the IG recommended that EPA develop national guidance that addresses issues such
as:
-recommended testing frequencies;
-discrepancies in test procedures; and
-inconsistent reporting of test results.
• In addition to national guidance, the IG recommended that EPA enhance its oversight
program.
• In response to the IG report, the Office of Enforcement and Compliance Assurance (OECA)
made a commitment to address the concerns raised in the report and provide clarification, as
necessary, on the issues identified. The Office of Compliance (OC) was given the responsibility
for satisfying this commitment.
• The concerns associated with testing frequencies, and the reporting of test results were
addressed in the CAA Stationary Source Compliance Monitoring Strategy (CMS) issued by the
Agency in April 2001. The Timely And Appropriate Enforcement Response To High Priority
Violations Policy (HPV Policy) issued by the Agency in December 1998 provides
supplementary guidance by specifying how violations identified through stack testing should be
addressed. Each of these documents is summarized below for the reader’s convenience;
however, for a more thorough understanding of these policies, we suggest that the reader review
Page 2
the documents in their entirety.
-An electronic version of CMS can be obtained at:
www.epa.gov/compliance/resources/policies/monitoring/cmspolicy.pdf.
-The HPV Policy can be obtained at:
www.epa.gov/compliance/resources/policies/civil/caa/stationary/issue-ta-rpt.pdf.
-The website for the associated HPV Workbook is:
www.epa.gov/compliance/resources/policies/civil/caa/stationary/hpvmanualrevised.pdf.
• This stack testing guidance was developed to address the remaining issues raised by the IG,
specifically those associated with the conduct of stack tests. A Workgroup with representatives
from OECA, the Office of Air Quality Planning and Standards (OAQPS), and the EPA Regions
was formed to develop the guidance. In formulating this guidance, the Workgroup reviewed all
relevant Agency guidance and applicability determinations; evaluated all identified state
regulations and guidance on stack testing; and solicited state/local input in various forums.
• The discussion in this document is intended solely as guidance. This guidance is not a
regulation, nor is it intended to change any underlying regulatory requirements specified in
individual New Source Performance Standards (NSPS), National Emission Standards for
Hazardous Air Pollutants (NESHAP), NESHAP for Source Categories (MACT), state or local
regulations. This guidance merely documents and clarifies existing regulatory requirements and
Agency guidance on stack testing.
• It is not our practice to distribute guidance such as this for formal public notice and comment
as it does not supersede or alter existing regulatory requirements, nor impose any new legally
binding requirements on EPA, state/local agencies, or the regulated community. The general
description provided in this document may not apply to a particular situation based on the
circumstances. Furthermore, interested parties remain free to raise questions or objections about
the substance and application of the guidance as they arise in a particular situation. EPA retains
the discretion to adopt approaches on a case-by-case basis that differ from those described in this
guidance where appropriate. This document may be revised periodically without public notice.
• On February 2, 2004, EPA issued the stack testing guidance as interim to provide an
opportunity to evaluate its usage and monitor any potential problems with its implementation.
During the interim period, EPA received feedback from individual state/local agencies,
state/local air associations, and industry associations and representatives.
• On September 30, 2005, after reviewing all comments received on the interim guidance and
addressing such comments as appropriate, EPA issued final guidance. The final guidance
superceded the February 2, 2004 interim guidance. At the time of issuance of the final guidance,
EPA noted that the Agency would conduct notice and comment rulemaking regarding the
appropriate circumstances in which an extension of performance test deadlines may be allowed
by regulation.
Page 3
• On August 9, 2006, EPA published in the Federal Register (FR) proposed amendments to the
General Provisions for the NSPS, NESHAP, and MACT programs to allow source owners or
operators, in the event of a force majeure, to petition the Administrator for an extension of the
deadline(s) by which they are required to conduct an initial or subsequent performance test
required by applicable regulations.
• The proposed revisions to the NSPS, NESHAP, and MACT General Provisions became
effective on May 16, 2007. The revisions were extended to the Consolidated Federal Air Rule
(CFAR) (40 CFR Part 65) on August 27, 2007.
• This guidance dated April 27, 2009, supersedes the September 30, 2005, guidance. It
incorporates the amendments to the General Provisions and the CFAR which allow source
owners or operators to petition for an extension to the test deadlines as a result of a force majeure
event. It also includes other minor clarifications and revisions based on feedback EPA has
received since issuance of the guidance in 2005.
II GOALS OF THE NATIONAL STACK TESTING GUIDANCE
• Expand upon CMS and the HPV Policy to fully address the concerns raised by the IG on this
issue.
• Improve uniformity on how stack tests are conducted for determining and demonstrating
compliance with the NSPS (40 CFR Part 60), NESHAP (40 CFR Part 61), and MACT (40 CFR
Part 63).
• Improve coordination between EPA and state/local agencies.
• Enhance EPA oversight of state/local programs to ensure that the tool of stack testing is being
sufficiently and properly utilized.
III DEFINITION OF STACK TESTING
• Stack testing may be conducted for varying purposes, such as relative accuracy test audits
(RATAs), linearity checks, and routine calibration of continuous emission monitoring (CEM)
equipment. However, for purposes of this guidance, stack testing is being more narrowly
defined as:
-Any performance testing conducted for the purposes of determining and demonstrating
compliance with the applicable standards of 40 CFR Parts 60, 61, and 63 using
promulgated test methods, other test methods or procedures cited in the applicable
subpart(s), or alternative test methods approved by the Administrator under §§ 60.8,
61.13, or 63.7. It does not include visible emission observation testing.
Page 4
IV SCOPE OF GUIDANCE
• The guidance applies to tests conducted for the purposes of determining and demonstrating
compliance with NSPS, NESHAP, and MACT programs. The guidance does not apply to tests
in situations such as the following:
- tests requested by EPA to assist the Agency in the development of regulations or
emissions factors;
- tests to establish monitoring protocols for parametric monitoring under the Compliance
Assurance Monitoring requirements of 40 CFR Part 64;
- tests to develop and evaluate alternative test methods;
- tests voluntarily conducted by facilities for their own purposes to optimize operations
and improve energy efficiency;
- tests conducted only to determine and demonstrate compliance with state
Implementation Plan (SIP) requirements. (Tests conducted to simultaneously determine
and demonstrate compliance with NSPS, NESHAP, and MACT programs are included
within the scope of the guidance.)
• The data from tests conducted in situations such as those listed above may be subject to Title
V reporting requirements and need to be considered by the source when submitting reports and
certifying compliance pursuant to the Title V program.
CAA STATIONARY SOURCE COMPLIANCE MONITORING STRATEGY
• The CMS provides guidance on stationary source air compliance monitoring programs with a
focus on Title V major sources and synthetic minor sources that emit or have the potential to
emit at or above 80 percent of the Title V major threshold. It addresses the IG issues of when a
stack test should be conducted and what information should be reported nationally. It recognizes
that consistent, complete and accurate stack test information is critical in managing a national air
program. Hence, the CMS recommends:
-States/locals should conduct a stack test where there is no other means for determining
compliance with the emission limits. In determining whether a stack test is necessary,
states/locals should consider factors such as: size of emission unit; time elapsed since last
stack test; results of that test and margin of compliance; condition of control equipment;
and availability and results of associated monitoring data.
-States/locals should conduct a stack test whenever they deem appropriate regardless of
Page 5
whether there are other means for determining compliance.
-The date and results (Pass/Fail/Pending) of all stack tests should be entered in the
national air data system (AIRS/AFS, or its successor), and the High Priority Violations
(HPV) status adjusted as appropriate.
VI HIGH PRIORITY VIOLATIONS POLICY
• The HPV Policy provides guidance on how to define significant violations under the CAA at
major stationary sources, and the timely and appropriate enforcement response when such
violations are identified. It addresses the IG concern with consistent treatment of stack test
failures.
• Facilities are to be in compliance with applicable requirements at all times except during
periods of startup, shutdown or malfunction, or under circumstances as defined in the underlying
NSPS, NESHAP, or MACT standards or General Provisions to 40 CFR Parts 60 and 63.1 All
stack test failures should be reviewed by the delegated agency to determine whether a violation
has occurred, and if so, the appropriate enforcement response. The enforcement response should
be consistent with the HPV Policy which states:
"The following criteria trigger HPV status. . . Violations that involve testing, monitoring,
recordkeeping or reporting that substantially interfere with enforcement or determining
the source’s compliance with applicable emission limits. . . A violation of an allowable
emission limit detected during a reference method stack test." See HPV Policy, pp. 3-4.
See also HPV Workbook, p. 3.5.
• Violations of emission limits for pollutants for which a facility is not designated as a "major "
source may not rise to the level of HPV. The guidance addresses such circumstances by stating:
"EPA expects that all violations of air pollution regulations, whether meeting the HPV
criteria or not, will be addressed by states, local agencies, or EPA." See HPV
Policy, p. 2.
• The HPV Policy does not apply in situations where the delegated agency accepts a facility’s
claim that it was unable to conduct an initial performance test within the regulatory deadline due
to a Force Majeure Event. A more detailed discussion of such an event is described below in the
Section, "The Time Frame for Conducting Stack Tests."
1 The Agency has issued separate guidance for SIPs on how to address excess emissions
during start-up, shutdown or malfunctions.
Page 6
VII MAJOR ISSUES
• The guidance addresses the following major issues:
1. The Time Frame for Conducting Stack Tests
2. Stack Test Waivers
3. Stack Test Notifications
4. Observation of Stack Tests
5. Representative Testing Conditions
6. Stoppages
7. Postponements
8. Test Reports
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1. The Time Frame for Conducting Stack Tests
2. Stack Test Waivers
3. Stack Test Notifications
4. Observation of Stack Tests
5. Representative Testing Conditions
6. Stoppages
7. Postponements
8. Test Reports
2. Stack Test Waivers
3. Stack Test Notifications
4. Observation of Stack Tests
5. Representative Testing Conditions
6. Stoppages
7. Postponements
8. Test Reports
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