Lessons Learned from Continuous Emissions Monitoring Users Group (CEMUG)
Conference
The seventeenth annual meeting of the Continuous Emissions Monitoring Users Group
(CEMUG) was held May 14-16, 2008, in Nashville, Tennessee. The meeting brought
together more than 600 attendees to better understand the latest regulatory decisions,
describe experience using CEM equipment, and share solutions to common operating
problems. The meeting was co-hosted by EPRI and Tennessee Valley Authority.
Information was presented in several areas, including regulatory updates, mass particulate
monitoring, mercury monitoring, reference method development, and advanced
monitoring technologies and methods.
Opening Remarks and Regulatory Update
 George Offen, EPRI Senior Technical Executive and Manager of EPRI’s
Environmental Controls Programs, welcomed attendees to the meeting. Reviewing
the status of mercury monitoring, he noted that the recent decision by the U.S.
District of Columbia Circuit Court of Appeals vacating the Clean Air Mercury Rule
(CAMR) had created short-term uncertainty, although the needs for long-term
monitoring remain unchanged. Most mercury CEM purchase decisions have been
made. For example, as of April 28, it was estimated that orders had been placed for
665 continuous analyzers, 110 Appendix K systems, and 85 low emitters. However,
fewer than 50% of the continuous analyzers and 25% of the Appendix K systems
have been installed.
In addition, a number of key issues remain to be resolved. The orders were shipped
without NIST (National Institute of Standards and Technology) traceable calibrators,
so that NIST traceability must be resolved in the field, and valid quality assurance
and quality control procedures must be developed. Stratification in mercury testing
must be resolved. In addition, users need to know how to report results in the absence
of Part 75, and to understand the value of mercury data for future regulatory actions.
Offen also noted the continuing challenges in developing monitoring technologies
beyond those for mercury—for particulates and sulfur trioxide (SO3).

Reynaldo (Rey) Forte, Director of the Emission Monitoring Group of the U.S.
Environmental Protection Agency (EPA), reviewed recent regulatory issues,
including the Clean Air Interstate Rule (CAIR), General Part 75, mercury monitoring,
and the mandatory greenhouse gas (GHG) emissions reporting rule.
Forte described EPA’s implementation of CAIR to date, including development of
NOx certification guidance, reporting instructions, and regional workshops and
training materials. (Note: Following the CEMUG Conference, on July 11, 2008, the
D.C. Circuit vacated CAIR, and the EPA is currently reviewing the Court's decisions
and evaluating its impacts.)
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On General Part 75, Forte said that revisions to clarify and correct mistakes in
existing requirements were effective January 2008. The Protocol Gas Verification
Program (PGVP) is proceeding, and as of January 1, 2009, any EPA Protocol Gases
used under Part 75 must be from a gas producer participating in the PGVP. Also, on
January 1, 2009, new stack testing competency requirements (ASTM D 7036-04) take
effect. A number of sources have successfully reported emissions using the Emissions
Collections and Monitoring Plan System (ECMPS).
In the area of mercury monitoring, EPA continues its commitment to developing a
complete mercury monitoring capability, and is supporting a large field
demonstration of NIST traceability and calibration gas protocols. Forte said that the
mandatory GHG reporting is intended to provide data that will inform and support
development of a national climate policy, but that the rule is not likely to have a
major impact on sources already reporting under the Acid Rain Program.
Mass Particulate Monitoring
 John Cooper, of Cooper Environmental Services, described his company’s
development of the Multi-Metals Quantitative reference Aerosol Generator (MultiMetals QAGTM) and the Particulate Matter QAG (PM QAGTM), which can be used
for evaluating the precision, linearity, and accuracy of metals and PM monitors.
The QAG devices may be used for an independent quality assurance (QA) check of
MM CEMS and may be useful for PM CEMS calibration, validation, certification,
and audits. The QAGs address some of the challenges of current QA audits, which are
time consuming, costly, and require modification of plant operations. The QAG
devices are on and off in seconds, and the emission rate is measured during each test.
The devices are accurate, stable, and repeatable. The results are traceable to NIST
standards. The MM QAG has been approved by EPA for MM CEMS audits.
Following the conference, field tests of the PM QAG are planned. Design
improvements are also planned to reduce the QAG’s size, improve its user
friendliness, and automate key functions.
Mercury Monitoring
 Jeremy Whorton of Thermo Fisher Scientific, described lessons learned in preparing
for Relative Accuracy Test Audits (RATAs). Mercury RATAs and CEMS are still
new to many utility users, and many mercury CEMS have not conducted RATAs.
The presenters expressed the hope that their experience could help others pass their
RATAs. The RATAs were conducted at NPPD’s Sheldon Station Units 1 and 2.
Darnell and Whorton recommended a number of steps to take in advance to prepare
for the RATAs, including testing for CEM calibration error, linearity, and cycle
response time. They also suggested collecting Method 30B traps from the plant’s gas
generator to sample the gas coming out of the 81i calibrator. Another
recommendation was to cross-check the gas generator by connecting the output of
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one calibrator to another. Weekly system integrity checks were also conducted for the
chlorine setup.
One of the challenges with Method 30B is that if concentration changes during the
RATA, even if it seems insignificant, one needs to ensure that 30B QA checks,
including spike targets and permissible sample mass ranges, are within tolerance. The
Method 30B QA of the trap is very specific to the initial concentration values when
choosing the sampling parameters. If the concentration values shift from the initial,
one cannot assume that the QA is valid. The presenters found that a Method 30B
RATA can be conducted in two working says, even with low concentrations in the
flue gas.

Lauren Freeman, of Hunton and Freeman LLP, explained the legal issues
surrounding the Circuit Court’s February 8, 2008 decision vacating CAMR. Freeman
noted that the court vacated both CAMR and EPA’s Section 112(n) Revision Rule,
which is a special provision of the Clean Air Act (CAA) on the regulation of
hazardous air pollutants at electric utilities. The court’s decision interpreted the CAA
as requiring any change in EPA’s Section 112(n) finding to also satisfy the much
more specific “delisting” criteria in CAA Section 112(n) that apply to other source
categories. Because the Revision Rule did not follow that procedure, CAMR is also
invalid.
On March 24, EPA and the Utility Air Regulatory Group (UARG) separately sought a
rehearing by the full court. If the rehearing is denied, EPA and UARG have 90 days
to appeal the denial to the Supreme Court. If and when CAMR is put back into effect,
there is no provision for automatic adjustment of deadlines. If states move forward,
they are doing so under state law, not the CAA.

Richard McRanie, of RMB Consulting & Research Inc., described the results of a
project to field-test mercury (Hg) calibrators. The study’s goals were to evaluate the
stability of elemental Hg head space calibrators, evaluate vendor and field traceability
protocols, develop field certification procedures (NIST traceability), develop field
QA/QC procedures, and evaluate cylinder gases for QA/QC. The project sought to
compare installed calibrators to reference calibrators periodically using a defined
procedure, track any changes over time, and evaluate the stability of the calibrators
according to slope change, y-intercept change, and uncertainty. To date, the vendors
have prepared 14 reference calibrators, field comparison procedures have been
prepared, and several field comparison tests have been completed. A number of
problems have been identified. Tasks ahead are to resolve the nitrogen/air problems,
activate more field sites, have EPA sign off on draft procedures, and move forward on
laboratory studies.

Chuck Dene standing in for Sharon Sjostrom, of ADA-ES, Inc., described results
of mercury stratification testing. The testing used the ADA-ES IRM. The
Instrumental Reference Method, also known as the EPA Reference Method 30A, is
consistent with the SO2 and NOx IRM. Results are in real time and performance
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based. Tests were conducted at three plants: We Energies’ Presque Isle Power Plant,
Rocky Mountain’s Hardin Generating Station, and Entergy’s Independence Station.
At Presque Isle, mercury was found to be unstratified (<5% difference or < +/- 0.2
µg/µm3). SO2 was found to be minimally stratified (>5% of average value). At Hardin
Station, an exemption and a three-point RATA were allowed because Hg was <3
µg/m3. At Independence Station, the system almost passed as minimally stratified
(<10% difference or 0.5 µg/µm3). In summary, Sjostrom noted that SO2 should be a
reasonable surrogate for uncontrolled units, and a three-point RATA should be
allowed if Hg <3 µg/m3.
Reference Method Development
 Jeff Ryan, of EPA’s Office of Research and Development, provided an update on
Reference Methods 30B and 30A. Method 30B, or the Sorbent Trap Method
Reference Method, is now widely used. Its focus is on high-quality Hg measurements
at low sample methods. Ryan noted the importance of sorbent selection—the
cleanliness of carbon really determines how low you can go. The quality of spiking is
critical to field recovery test performance. Carbon sub-sampling and analysis are not
prohibited. Moisture determination using Method 4 is necessary when the Hg
monitoring system being evaluated or the emission limit is on wet basis. Method 30B
is not intended for high PM environments. Work is under way to adapt Method 30B
for speciation, and recent field testing has been positive. Ongoing activities include
continued optimization of thermal analysis system, continued evaluation of sorbent
traps, continued field evaluation of a speciating version of Method 30B, and a
comparison of trap spiking techniques.
Method 30A, or the Instrumental Reference Method (IRM), is not currently used, but
the approach and elements have been demonstrated. Its application is inhibited by
lack of suitable equipment and the unavailability of NIST-traceable gas standards.
Method 30A is a source of guidance for stratification/traversing requirements for all
Hg measurement methods. Ongoing activities include preparation of interim protocols
for Hg gas NIST traceability, stratification testing at sites where Activated Carbon
Injection used wet electrostatic precipitators, and continued development of IRMspecific equipment.

William Roberson, of RMB Consulting & Research Inc., described development and
field experience with Method 30B. The method requires a number of pre-test lab
procedures, including a matrix interference test, a Method Detection Limit (MDL)
study, a minimum calibration mass determination, a minimum sample mass
determination, and analytical bias tests with Hg0 and Hg+2. Pre-test sampling
procedures include meter calibrations and specifications, and sample point selection
and stratification.
The sampling procedures require paired trains and sorbent traps composed of two
sections (one for primary capture and the other for backup). Field Recovery Tests
require three paired train test runs with a pre-spiked trap. Average recovery must be
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between 85 and 115% recovery. Analytical procedures include a daily multipoint
calibration. Following testing, the gas meter must undergo a calibration check.
Advanced Monitoring Technologies and Methods
 Caleb Wiza, of Clean Air Engineering, Inc., reviewed SO3 measurement techniques.
There are two manual methods: EPA’s Method 8 and Controlled Condensation
(CCM). Method 8, also known as the Differential Absorption technique, has several
major weaknesses: lack of requirements for the sampling system, effects of aqueous
solutions, effects of chemical interferents, and the variability of the method. For
Method 8, it is suggested that users employ a particulate filter following the EPA
Method 5B, use high-purity filter media, heat the extraction system to at least 320°F,
recover the extraction system for analysis, employ an extract filter using IPA for
analysis, and titrate in 80% IPA “sweet spot.”
With CCM, limitations include interactions of the flue gas and particulates, and
saturated gas streams. It is suggested that users employ a filter-less extraction system,
dynamic spike, and paired sample trains.
Instrumental monitoring and measurement techniques include extractive and in-situ
approaches. Extractive methods include colorimetry and turbidimetry. Among in-situ
methods are dewpoint monitors and spectrographic methods (e.g., FTIR, differential
absorption, tunable diode lasers, and quantum cascade lasers).
Moving forward, the manual methods need organization and sponsorship, while the
instrumental techniques need a market. To accomplish this, stakeholders need to
come together to assess the viability and capability of the methods, and perform
validation studies.

Richard Cooper, of Cascade Technologies, reviewed the potential of quantum
cascade lasers (QCLs) for emissions monitoring. QCLs are a proven and available
technology. They use semiconductor lasers that operate in the mid-infrared, where all
gases have characteristic spectral fingerprints, and that provide unambiguous
identification and quantification. QCL technology provides results in real time,
responses over a large dynamic range, fixed calibration, and immunity to cross
interference. There is no need for correction curves for concentration, pressure,
temperature, and gas. The technology provides simultaneous measurement of
multiple compounds, including CO, CO2, SO3, NO, NO2, NH3, H2O, and N2O. The
technology is available as an in-situ probe or an extractive sampler.
The eighteenth CEM Users Group Meeting is planned for May 13-15, 2009 in St.
Louis, MO.
For more information contact Chuck Dene, 650-855-2425, cdene@epri.com.
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