[Federal Register: September 7, 2007 (Volume 72, Number 173)]
[Rules and Regulations]
[Page 51493-51531]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07se07-17]
[[Page 51493]]
-----------------------------------------------------------------------
Part II
Environmental Protection Agency
-----------------------------------------------------------------------
40 CFR Parts 60, 72 and 75
Two Optional Methods for Relative Accuracy Test Audits of Mercury
Monitoring Systems Installed on Combustion Flue Gas Streams and Several
Amendments to Related Mercury Monitoring Provisions; Final Rule
[[Page 51494]]
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 60, 72 and 75
[EPA-HQ-OAR-2007-0164, FRL-8459-8]
RIN 2060-AO01
Two Optional Methods for Relative Accuracy Test Audits of Mercury
Monitoring Systems Installed on Combustion Flue Gas Streams and Several
Amendments to Related Mercury Monitoring Provisions
AGENCY: Environmental Protection Agency (EPA).
ACTION: Direct final rule.
-----------------------------------------------------------------------
SUMMARY: EPA is taking direct final action on two optional methods for
relative accuracy audits of mercury monitoring systems installed on
combustion flue gas streams and several amendments to related mercury
monitoring provisions. This action approves two optional mercury (Hg)
emissions test methods for potential use in conjunction with an
existing regulatory requirement for Hg emissions monitoring, as well as
several revisions to the mercury monitoring provisions themselves. This
action is in regard to the testing and monitoring requirements for
mercury specified in the Federal Register on May 18, 2005. Since that
publication, EPA has received numerous comments concerning the
desirability of EPA evaluating and allowing use of the measurement
techniques addressed in the two optional methods in lieu of the methods
identified in the cited Federal Register publication, as they can
produce equally acceptable measures of the relative accuracy achieved
by Hg monitoring systems. This action allows use of these two optional
methods entirely at the discretion of the owner or operator of an
affected emission source in place of the two currently specified
methods. This direct final rule also amends Performance Specification
12A by adding Methods 30A and 30B to the list of reference methods
acceptable for measuring Hg concentration and the Hg monitoring
provisions of May 18, 2005, to reflect technical insights since gained
by EPA which will help to facilitate implementation including
clarification and increased regulatory flexibility for affected
sources.
DATES: This rule is effective on November 6, 2007 without further
notice, unless EPA receives adverse comment by October 9, 2007. If EPA
receives adverse comment, EPA will publish a timely withdrawal in the
Federal Register informing the public that some or all of the
amendments in this rule will not take effect.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2007-0164, by one of the following methods:
http://www.regulations.gov. Follow the on-line instructions for
submitting comments.
E-mail: a-and-r-docket@epa.gov.
Fax: (202) 566-9744.
Mail: Two Optional Methods for Relative Accuracy Test
Audits of Mercury Monitoring Systems Installed on Combustion Flue Gas
Streams and Several Amendments to the Related Mercury Monitoring
Provisions, Environmental Protection Agency, Mailcode: 2822T, 1200
Pennsylvania Avenue, NW., Washington, DC 20460. Please include a total
of two copies.
Hand Delivery: EPA Docket Center, 1301 Constitution
Avenue, NW., EPA Headquarters Library, Room 3334, EPA West Building,
Washington, DC 20460. Such deliveries are only accepted during the
Docket's normal hours of operation, and special arrangements should be
made for deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2007-0164. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information provided,
unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through http://www.regulations.gov or e-mail.
The http://www.regulations.gov Web site is an ``anonymous access'' system,
which means EPA will not know your identity or contact information
unless you provide it in the body of your comment. If you send an e-
mail comment directly to EPA without going through http://www.regulations.gov,
your e-mail address will be automatically captured and included as part
of the comment that is placed in the public docket and made available
on the Internet. If you submit an electronic comment, EPA recommends
that you include your name and other contact information in the body of
your comment and with any disk or CD-ROM you submit. If EPA cannot read
your comment due to technical difficulties and cannot contact you for
clarification, EPA may not be able to consider your comment. Electronic
files should avoid the use of special characters, any form of
encryption, and be free of any defects or viruses. For additional
information about EPA's public docket, visit the EPA Docket Center
homepage at http://www.epa.gov/epahome/dockets.htm.
Docket: All documents in the docket are listed in the
http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the Two Optional Methods for
Relative Accuracy Audits of Mercury Monitoring Systems Installed on
Combustion Flue Gas Streams Air and Radiation Docket, EPA/DC, EPA West
Building, EPA Headquaters Library, Room 3334, 1301 Constitution Avenue,
NW., Washington, DC. 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 Air and Radiation Docket is (202) 566-1742.
FOR FURTHER INFORMATION CONTACT: Either Mr. William Grimley, Office of
Air Quality Planning and Standards, Air Quality Assessment Division,
Measurement Technology Group (E143-02), EPA, Research Triangle Park, NC
27711, telephone (919) 541-1065, facsimile number (919) 541-0516, e-
mail address: grimley.william@epa.gov or Ms. Robin Segall, Office of
Air Quality Planning and Standards, Air Quality Assessment Division,
Measurement Technology Group (E143-02), EPA, Research Triangle Park, NC
27711, telephone (919) 541-0893, facsimile number (919) 541-0516, e-
mail address: segall.robin@epa.gov.
SUPPLEMENTARY INFORMATION:
I. Why is EPA using a Direct Final Rule?
EPA is publishing this rule without a prior proposed rule because
we view this as a noncontroversial action and anticipate no adverse
comment. The most important benefit of direct final rulemaking for this
action is to provide: (1) Additional reference method options, and (2)
judicious revisions to mercury monitoring provisions specified in the
Federal Register on May 18, 2005 that, if successful, relieve affected
facilities of uncertainty regarding final emission monitoring
requirements and certification details as opposed to waiting through a
potentially protracted proposal/final
[[Page 51495]]
rulemaking process. Insofar as the two methods are concerned, EPA
believes that they contain the necessary elements to generate
acceptable data quality without being unduly burdensome. Through
experience gained from developing existing performance based methods
and trading rules, EPA has learned to identify test method criteria
significant to effective rule implementation. EPA believes each of the
two methods adopted in this action contain adequate specific criteria
and procedures essential to the accurate measurement of Hg emissions,
without adversely compromising the goals of performance-based
methodology. EPA will continue to support and advance the principles
and practicality of these methods by adding detailed method application
information to facilitate their use to the Web site http://www.epa.gov/airmarkets/
as it becomes available. Since use of either of these
methods is not mandatory, but optional, there should be no objection to
their availability. Regarding the amendments to the Hg emission
monitoring provisions of 40 CFR parts 72 and 75, these amendments
reflect EPA's increased technical understanding since the May 18, 2005
rulemaking. However, in the ``Proposed Rules'' section of today's
Federal Register, we are publishing a separate document that will serve
as the proposed rule to approve provisions, if any, of this direct
final rule that receive relevant adverse comments on this direct final
rule. We will not institute a second comment period on this action. Any
parties interested in commenting must do so at this time. For further
information about commenting on this rule, see the ADDRESSES section of
this document.
If EPA receives adverse comment on one or more distinct provisions
of this rulemaking, we will publish a timely withdrawal in the Federal
Register indicating which provisions we are withdrawing and informing
the public that those provisions will not take effect. The provisions
that are not withdrawn will become effective on the date set out above,
notwithstanding adverse comment on any other provision. We would
address all public comments in a subsequent final rule based on the
proposed rule.
II. Does This Action Apply to Me?
Regulated Entities. The regulated categories and entities affected
by this direct final rule include:
------------------------------------------------------------------------
Examples of regulated
Category NAICS \a\ entities
------------------------------------------------------------------------
Industry....................... 221112 Fossil fuel-fired
electric utility steam
generating units.
Federal government............. \b\ 221122 Fossil fuel-fired
electric utility steam
generating units owned
by the Federal
government.
State/local governments........ \b\ 221122 Fossil fuel-fired
electric utility steam
generating units owned
by municipalities.
Tribal governments............. 921150 Fossil fuel-fired
electric utility steam
generating units in
Indian country.
------------------------------------------------------------------------
\a\ North American Industry Classification System.
\b\ Federal, State, or local government-owned and operated
establishments are classified according to the activity in which they
are engaged.
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
direct final rule. If you have any questions regarding the
applicability of this direct final rule to a particular entity, consult
either the air permit authority for the entity or your EPA regional
representative as listed in 40 CFR 63.13.
III. Where Can I Obtain a Copy of This Action?
In addition to being available in the docket, an electronic copy of
this direct final rule is also available on the World Wide Web through
the Technology Transfer Network (TTN). Following signature, a copy of
this direct final rule will be posted on the TTN's policy and guidance
page for newly proposed or promulgated rules at the following address:
http://www.epa.gov/ttn/oarpg. The TTN provides information and
technology exchange in various areas of air pollution control.
IV. How Is This Document Organized?
The information presented in this preamble is organized as
follows:
I. Why Is EPA Using a Direct Final Rule?
II. Does This Action Apply to Me?
III. Where Can I Obtain a Copy of This Action?
IV. How Is This Document Organized?
V. Background
VI. This Action
VII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
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 and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Congressional Review Act
V. Background
On May 18, 2005, in the preamble of the Clean Air Mercury Rule
(CAMR) (70 FR 28608), EPA stated its intention to propose and
promulgate an instrumental reference method as an alternative to the
use of ASTM Method D6784-02 (the Ontario Hydro Method) to perform
Relative Accuracy Test Audits (RATAs) of Hg continuous emission
monitoring systems (CEMS) and sorbent trap monitoring systems used to
monitor Hg emissions from coal-fired power plants.
In comments on the proposed CAMR, commenters had two primary
objections to the use of the Ontario Hydro Method as the reference test
method for RATAs. Some expressed concern that the complexity of this
wet chemical method could lead to results that would cause a properly
functioning Hg CEMS to fail a RATA. Other commenters noted that, unlike
instrumental reference methods used to audit CEMS for SO2
and NOX that provide real-time values, test results from the
Ontario Hydro Method can take weeks to be received from the laboratory.
Commenters stated that this time lag can lead to implementation
problems with regard to both missing data and emissions reporting.
Since the CAMR was promulgated, EPA has proposed changes to 40 CFR
part 75, which would allow the use of EPA Method 29, with enhanced
quality-assurance procedures, as an alternative Hg reference method (71
FR 49257; August 22, 2006). Although Method 29 is somewhat simpler than
the Ontario Hydro Method and is more familiar to stack testers and
State regulatory agencies, it is also a wet chemistry method and is,
therefore, subject to the same limitations that make the Ontario Hydro
method less than optimal for RATA testing.
In view of these considerations, EPA believes that for RATA
testing, an instrumental Hg reference method
[[Page 51496]]
would be preferable to both the Ontario Hydro Method and to Method 29.
An instrumental method would provide real-time data that would best
facilitate implementation of a mercury cap and trade program.
Therefore, this action approves a performance-based instrumental
reference method for measuring Hg emission concentrations.
Another commenter to the proposed CAMR recommended that the sorbent
trap monitoring approach, now specified in 40 CFR part 75, appendix K,
be considered for use as a reference method. Although EPA did not
commit to establishing a sorbent trap reference method at the time of
CAMR promulgation, stakeholder interest in this methodology has
increased significantly. In an August 22, 2006 Federal Register notice,
EPA solicited comment on the use of sorbent trap technology for Hg
reference method testing, and numerous supportive comments were
received. In view of this, we initiated a review of available
historical test data where concurrent measurements of Hg concentration
were made with sorbent trap systems and either the Ontario Hydro Method
or Method 29. These data, taken together with additional supporting
data from recent field tests that were performed after the CAMR was
promulgated, suggest that using the sorbent trap methodology for Hg
reference method testing is viable. The Hg sorbent trap approach is
less onerous to use than either Ontario Hydro or Method 29, and
although it does not measure real-time Hg concentrations, a thermal
technique can be used to analyze the samples on the same day that they
are collected, facilitating RATA testing in the context of a cap and
trade program. Therefore, this action also approves a sorbent trap
reference method for Hg, as an alternative to the Ontario Hydro Method
and Method 29.
This direct final rule also includes several carefully considered
amendments to the Hg emission monitoring provisions of 40 CFR parts 72
and 75. EPA believes these amendments will facilitate implementation of
the CAMR by clarifying portions of that rule and by providing added
regulatory flexibility to the affected sources.
VI. This Action
This direct final rule allows for the earliest possible use of two
optional reference test methods for measuring total vapor phase mercury
emissions from stationary sources as well as several related amendments
to the Hg monitoring provisions of the CAMR. Both an instrumental test
method and a sorbent trap test method for measurement of total vapor
phase mercury emissions are being added to Appendix A-8 of 40 CFR part
60 as approved alternatives to the Ontario Hydro Method and EPA Method
29 to perform RATAs of installed mercury monitoring systems. The two
methods are discussed below, and the related amendments are explained
in detail later in this section.
The first method being added to appendix A-8 of 40 CFR part 60
today is titled ``Method 30A--Determination of Total Vapor Phase
Mercury Emissions from Stationary Sources (Instrumental Analyzer
Procedure).'' In Method 30A, a sample of the effluent gas is
continuously extracted and conveyed to an analyzer capable of measuring
the total vapor phase Hg concentration. Elemental and oxidized mercury
(i.e., Hg\0\ and Hg+\2\) may be measured separately or
simultaneously but, for purposes of this method, total vapor phase Hg
is the sum of Hg\0\ and Hg+\2\. Method 30A provides test
program-specific verification of method performance using a dynamic
spiking approach, coupled with other performance criteria, which
include system calibration, interference testing, and system integrity/
drift checks. The dynamic spiking requirement, which is a gaseous
``method of standard additions,'' is the only part of Method 30A not
parallel to the routinely applied instrumental reference methods used
to perform relative accuracy testing of CEMS for SO2 and
NOX. The dynamic spiking procedure is included in Method 30A
to characterize measurement bias for Hg, which can be highly reactive
on a site-specific basis (i.e., for each emissions sample matrix), with
recovery criteria set to ensure that the bias is held to a minimal
level. All performance requirements of Method 30A must be met for the
data to be considered valid. The availability of an instrumental
reference method for Hg testing is consistent with the approach EPA has
taken in the successful Acid Rain and NOX Budget emissions
trading programs.
Method 30A is performance based in keeping with the criteria
established under our Notice of Intent to Implement Performance Based
Measurement Systems for Environmental Monitoring (62 FR 52098, October
6, 1997). Use of the performance-based measurement approach will allow
for continued development and application of new, improved, and more
cost-effective Hg measurement technologies while ensuring the
collection of data of known quality.
Based on EPA's experience in conducting test programs to evaluate
the procedures and performance criteria included in Method 30A, EPA
recognizes that although prototypes of all equipment needed to perform
this method have been successfully demonstrated in the field, at
present the equipment needed to follow all procedures required by the
method is commercially available only on a limited basis, and is being
further refined. One of the issues of greatest concern in the
development of an instrumental reference method for Hg has been the
design of the sampling probe. Most of the commercially-available probes
suitable for Hg measurement are very heavy (over 100 lbs.) making it
difficult to move the probe from point-to-point and port-to-port for Hg
stratification testing and/or sample traverses. Much progress is being
made in probe redesign. One manufacturer has recently developed a probe
that weighs less than 40 lbs., samples at significantly lower flow
rates, and is suitable for dynamic spiking. Additional field testing of
this probe and others currently under development is underway, and EPA
plans to continue to actively encourage equipment development and
evaluation. To encourage the use of Method 30A, including further
development of the supporting equipment, which we believe will
eventually enable source testers to perform Hg monitoring system RATAs
more efficiently and will become the reference method of choice for
many testing companies and affected sources, we are deferring the
requirement for implementation of the dynamic spiking and Hg
stratification test procedures until January 1, 2009. EPA believes this
deferral is reasonable because Hg monitoring data reported to EPA in
2009 will not be used in the trading of Hg allowances, as allowance
accounting under the CAMR does not begin until 2010. Source testers are
encouraged to use this time to acquire the necessary equipment and
familiarize themselves with these procedures. Also, for all emissions
test programs and RATAs performed under CAMR prior to January 1, 2009,
we are allowing either: (1) A 12-point traverse for sulfur dioxide
(SO2) to be substituted for a 12-point Hg traverse, in cases
where stratification testing is used to determine the appropriate
number and location of the reference method sampling points, or (2) use
of the alternate three-point traverse line (0.4, 1.2, and 2.0 meters
from the stack wall) as specified in section 8.1.3.2 of Performance
Specification 2 (40 CFR part 60, appendix B). We
[[Page 51497]]
believe that in the short-term, these temporary deferrals will
encourage the application of Method 30A and will help affected CAMR
sources meet the January 1, 2009 deadline for initial certification of
the required Hg monitoring systems. Several additional Method 30A
development considerations are worthy of note. A preliminary draft of
Method 30A was first available for public consideration on an EPA Web
site (http://www.epa.gov/ttn/emc/) on February 28, 2006. Since that time, EPA
and several stakeholder groups have evaluated the various technical
aspects of the method. Based on the combined laboratory and field
observations, EPA has been able to simplify several procedural
requirements that we believe are essential to the method. The dynamic
spiking requirement (for test program-specific verification of
measurement system data quality) has been reduced to only a pretest
requirement. The interference test has been made optional. The three-
point system calibration error test using Hg+\2\ has been
streamlined to a system integrity check using a zero gas and a single
upscale Hg+\2\ gas. Another change has been to relax the
Hg\0\ calibration error specification from 2 percent to 5 percent of
span, in recognition of the fact that this procedure is a check of the
entire measurement system, as well as the current knowledge regarding
the uncertainty of NIST traceable standards. EPA does plan, however, to
reconsider this specification relaxation as more field data become
available. A final consideration in development of Method 30A has been
the requirement for calibration with both Hg\0\ and Hg+\2\.
Some stakeholders have recommended that we eliminate the Hg\0\
calibration and rely solely on the Hg+\2\ calibration. EPA,
however, believes this approach would not be adequate, because if only
Hg+\2\ were used, instrument calibration response adjustment
could compensate for an unknown amount of converter inefficiency, which
would then result in an inaccurate total mercury measurement in
situations where Hg\0\ is an appreciable fraction of the total stack
gas Hg.
The second method being added to appendix A-8 of 40 CFR part 60
today is titled ``Method 30B--Use of Sorbent Traps to Measure Total
Vapor Phase Mercury Emissions from Coal-Fired Combustion Sources.'' In
Method 30B, a sample of the effluent gas is continuously drawn through
a series of tubes containing activated carbon or another sorbent
material. After sampling, the tubes are sealed. The Hg captured by the
sorbent is then either: (1) Thermally desorbed and analyzed; or (2) the
tubes are transferred to a laboratory for extraction of Hg and
analysis. Like Method 30A, Method 30B is a performance-based method and
contains performance specifications and procedures for hardware
selection and calibration, sorbent spiking, and analytical recovery/
analysis which allow for development and application of new, improved,
and more cost-effective Hg measurement technologies while still
ensuring the collection of data of known quality. In particular, Method
30B contains five key measurement performance tests designed to ensure:
(1) Selection of a sorbent and analytical technique combination capable
of quantitative collection and analysis of gaseous Hg, (2) collection
during field testing of enough Hg on each sorbent trap to be reliably
quantified, and (3) adequate performance of the method for each test
program.
In considering development of a sorbent trap-based reference
method, EPA has reviewed historical emissions data where sorbent trap
measurement systems were operated concurrently with either the Ontario
Hydro Method or Method 29 (40 CFR part 60, appendix A-8). EPA has also
conducted several field test evaluations of sorbent trap systems versus
the Ontario Hydro Method in collaboration with the Electric Power
Research Institute (EPRI). Based on these efforts, we have concluded
that a sorbent trap-based technique coupled with appropriate
performance criteria and QA procedures can provide Hg emissions data of
quality comparable to that produced by the Ontario Hydro Method. Data
supporting this conclusion are presented in the docket, EPA-HQ-OAR-
2007-0164.
As we have done for Method 30A, for Method 30B emission tests and
RATAs performed prior to January 1, 2009, we are allowing either: (1) A
12-point traverse for sulfur dioxide (SO2) to be substituted
for a 12-point Hg traverse for the stratification testing used to
determine the number and location of the reference method sampling
points, or (2) use of the alternate three-point traverse line (0.4,
1.2, and 2.0 meters from the stack wall) as specified in section
8.1.3.2 of Performance Specification 2 (40 CFR part 60, appendix B). We
also intend to extend this temporary deferral of mercury stratification
testing to application of the Ontario Hydro Method and Method 29. EPA
believes this deferral is reasonable because Hg monitoring data
reported to EPA in 2009 will not be used in the trading of Hg
allowances, as allowance accounting under the CAMR does not begin until
2010.
This direct final rule also amends Performance Specification 12A of
appendix B to part 60 by adding Methods 30A and 30B to the list of
reference methods acceptable for relative accuracy testing of Hg
emissions monitoring systems. Once this direct final rule becomes
effective, the reference methods acceptable for Hg measurement in
Performance Specification 12A will include Methods 29, 30A, 30B, and
ASTM D6784-02.
With today's action, EPA is taking the opportunity to include
several considered revisions to the Hg emission monitoring provisions
of 40 CFR parts 72 and 75 as described in detail below. EPA is
including these revisions in this direct final rule because we believe
that they will facilitate implementation of the Hg monitoring under
CAMR.
First, Sec. 75.81(a) is being revised to confirm that the Hg CEMS
and sorbent trap monitoring systems required under subpart I of part 75
are to measure the total vapor phase mass concentration of Hg in the
flue gas, including both the elemental and oxidized forms of Hg,
expressed in units of micrograms per standard cubic meter ([mu]g/scm).
Although it is generally understood that total vapor phase Hg is the
regulated pollutant under CAMR, it recently was brought to EPA's
attention that subpart I of part 75 does not explicitly state that Hg
monitoring systems only need to measure total vapor phase Hg. The
amended language in Sec. 75.81(a) clarifies this.
Second, paragraph (i) in Sec. 75.15 is being revised and a new
paragraph (d)(2)(ix) is being added to Sec. 75.20, to codify the rules
for using optional non-redundant (``cold'') backup Hg monitoring
systems and like-kind replacement Hg analyzers, when the primary Hg
monitoring system is unable to provide quality-assured data. For the
other types of monitoring systems required by part 75, these monitoring
options have been in place since May 1999 (see 64 FR 28597, May 26,
1999). Today's action simply extends these provisions to Hg monitoring
systems. Through the years, the regulated community has found these
backup monitoring options to be beneficial, in that they minimize the
use of missing data substitution procedures during outages of the
primary monitoring system.
In particular, Sec. 75.20(d)(2)(ix) specifies that a non-redundant
backup Hg monitoring system can either be a Hg CEMS or a sorbent trap
monitoring system. The non-redundant backup Hg
[[Page 51498]]
monitoring system must be initially certified at each unit or stack
location where it will be used, in accordance with Sec.
75.20(d)(2)(i). For a non-redundant backup Hg CEMS, all of the initial
certification tests specified in Sec. 75.20(c)(1) are required, except
for the 7-day calibration error test. However, for ongoing quality
assurance (QA), a RATA is required only once every two years (8
calendar quarters), as specified in Sec. 75.20(d)(2)(vi). For a non-
redundant backup sorbent trap monitoring system, a RATA is required for
initial certification, and once every two years thereafter for ongoing
QA.
When a certified non-redundant backup Hg CEMS or a like-kind
replacement Hg analyzer is brought into service, a three-point
linearity check with elemental Hg standards and a single-point system
integrity check will be required. Alternatively, a three-level system
integrity check may be performed instead of these two tests. When a
certified non-redundant backup sorbent trap monitoring system is
brought into service, only the routine sampling and QA procedures of
Sec. 75.15 and appendix K of part 75 will be required.
Each non-redundant backup Hg monitoring system and each like-kind
replacement Hg analyzer will be subject to the applicable ongoing QA
requirements, restrictions and conditions specified in Sec.
75.20(d)(2). For certified non-redundant backup Hg CEMS and like-kind
replacement Hg analyzers, the weekly system integrity checks described
in section 2.6 of appendix B of 40 CFR part 75 will also be required as
long as the system or analyzer remains in service, unless the daily
calibration error tests of the analyzer are done using NIST-traceable
oxidized Hg standards.
Third, a new paragraph (k) is being added to Sec. 75.15 that: (1)
Clarifies that, when the RATA of an appendix K sorbent trap monitoring
system is performed, the type of sorbent material used in the appendix
K sorbent traps must be the same as that used for daily operation of
the appendix K monitoring system, and (2) allows the appendix K traps
used during RATA testing to be smaller than the traps used for daily
operation of the appendix K monitoring system. This change will be
particularly advantageous at very low Hg concentrations as it will
facilitate shorter RATA test run times. Parallel changes are being made
to section 6.5.7 of appendix A of part 75 to be consistent with the
provisions of Sec. 75.15(k). Section 6.5.7 currently requires the
appendix K sorbent traps used for the RATA to be the same size as the
traps used for daily operation of the appendix K monitoring system.
Fourth, today's action revises a number of sections of part 75,
appendix K, pertaining to the use of sorbent trap monitoring systems.
EPA is withdrawing the requirement to use the percentage recovery of
the elemental Hg spike in section 3 of each sorbent trap to adjust or
``normalize'' the Hg mass collected in sections 1 and 2 of the trap.
The requirement to spike the third section of each trap is being
retained and data from each pair of traps must still be invalidated if
either or both spike recovery percentages fall outside the acceptable
limits;\1\ however, the results of the spike recoveries will no longer
be used to adjust the Hg mass collected in the first two sections of
the traps. EPA is making this rule change based on an analysis of
recent spike recovery data from long-term appendix K field
demonstrations. Although the vast majority of the spike recoveries in
these studies have been within the currently acceptable limits of 75 to
125 percent, the requirement to normalize based on spike recovery could
affect data precision. For a given pair of traps, if one spike recovery
was high (e.g., 110 percent) and the other one low (e.g., 90 percent),
normalization of the Hg mass collected in the first two trap sections
using third section spike recoveries could make it difficult for a pair
of sorbent traps to meet the relative deviation (RD) specifications in
appendix K. In the example cited, normalization of the data would cause
the Hg concentrations measured by the traps to be adjusted by 10
percent in opposite directions, i.e., one upward and one downward.
Thus, two Hg concentrations that may have been in close agreement
without normalization now might not be able to meet the RD
specifications. In view of this, EPA has concluded that evaluating the
spike recovery data on a pass/fail basis instead of using the percent
recovery values to adjust the emissions data is more technically sound
and is also consistent with the way in which the results of daily and
quarterly QA assessments of CEMS are interpreted.
---------------------------------------------------------------------------
\1\ On August 22, 2006, EPA proposed to amend Appendix K to
allow the data from a pair of sorbent traps to be validated in cases
where the third section spike recovery from only one of the traps
meets the percent recovery specifications (see 71 FR 49275). EPA
proposed to allow the results from the trap that meets the
specifications to be used for reporting, provided that a single trap
adjustment factor (STAF) of 1.222 is applied. EPA is evaluating the
comments received on this proposal and expects to publish the final
rule in the summer of 2007.
---------------------------------------------------------------------------
Regarding the range of acceptable third section spike recoveries,
EPA is not changing the 75 to 125 percent acceptance criteria. As
previously noted, early field experience with appendix K monitoring
systems has demonstrated that spike recoveries within this range are
achievable. However, recent appendix K data indicate that more
stringent acceptance criteria may be justifiable. It appears that there
has been a marked improvement in third section spike recovery
percentages. Recoveries in the range from 85 to 115 percent are
consistently being achieved. If this trend continues, EPA may propose
to tighten the spike recovery acceptance criteria in a future
rulemaking. Toward that end, EPA will continue to collect and evaluate
third section spike recovery data from appendix K monitoring systems in
the months ahead.
To effect these changes to appendix K, section 11.5 is being
removed and reserved; section 10.4 is being revised; Equations K-6 and
K-7 are being redesignated as Equations K-5 and K-6, respectively; and
the definition of ``M*'' in redesignated Equation K-5 is being revised.
EPA is also revising appendix K to allow the owner or operator to
use other types of gas flow meters besides the conventional dry gas
meter (DGM) to quantify sample gas volume. Since the publication of
appendix K (see 70 FR 28695, May 18, 2005), numerous requests have been
received from the regulated community to allow this flexibility. In
response to these requests, EPA initiated an investigation of the
feasibility of replacing the DGM in a sorbent trap monitoring system
with a thermal mass flow meter. As a result of its investigation, EPA
has concluded that a properly calibrated thermal mass flow meter can be
at least as accurate as a DGM. The mass flow meter is also a more
modern technology than the DGM; since it has no moving parts, it may be
more reliable than a DGM for continuous duty.
Having found one type of gas flow meter that can measure as
accurately as a DGM, EPA is persuaded that there may be other
commercially available gas flow meter technologies that are equally
capable and may be suitable for appendix K applications. Accordingly,
EPA has decided that a performance-based approach, rather than a
prescriptive one, is more appropriate for appendix K gas flow meters.
Today's action allows the use of any type of gas flow meter that is
capable of accurately measuring gas volumes to within 2 percent.
Section 9.2.2.1 of appendix K now requires the manufacturer of the
gas flow meter to perform all necessary set-
[[Page 51499]]
up, testing, programming, etc. of the meter and to provide any
necessary instructions so that for the particular field application,
the meter will give an accurate readout of dry gas volume in units of
standard cubic meters. Then, prior to its initial use, the flow meter
must be calibrated at a minimum of three settings covering the expected
range of sample flow rates for the appendix K system. The initial
calibration may be performed either by the manufacturer or by the end
user. The calibration of the gas flow meter must be checked quarterly
thereafter, at an intermediate flow rate. For mass flow meters, the
initial three-point calibration must be performed by using either a
compressed gas mixture containing CO2, O2, and
N2 in proportions representative of the stack gas
composition or by using the actual stack gas. However, when the initial
calibration is done with a compressed gas mixture, the mass flow meter
may not be used until an additional on-site calibration check of the
flow meter at an intermediate flow rate is performed and passed, using
the actual stack gas.
To calibrate the gas flow meter, the owner or operator may either
follow the basic procedures in section 10.3 or section 16 of Method 5
in appendix A-3 of part 60 for calibration of dry gas meters, or
alternatively, may temporarily install a reference gas flow meter
(RGFM) at the discharge of the appendix K monitoring system while the
monitoring system is in operation and make concurrent measurements of
dry stack gas volume with the RGFM and the appendix K gas flow meter.
If the latter option is chosen, the RGFM may either be a gas flow
metering device that has been calibrated according to section 10.3.1 or
section 16 of Method 5 or a NIST-traceable volumetric calibration
device with an accuracy of 1 percent. Note that this
alternative calibration technique allows required QA checks to be
performed with little or no disruption of the operation of the sorbent
trap monitoring system.
Regardless of which calibration approach is used, a calibration
factor, Yi, must be obtained at each tested flow rate, where
Yi is the ratio of the volume measured by the reference
meter to the volume measured by the flow meter being calibrated. For
the initial three-point calibration, the three Yi values
must be averaged, and each individual Yi must be within
0.02 of the average value. The average value, Y, must then
be used to correct the gas volumes measured by the gas flow meter. For
single-level calibration checks (e.g., the quarterly checks performed
for routine QA), the Yi value obtained at the tested flow
rate must be compared with the current value of Y. If Yi
differs from Y by more than 5 percent, a full three-point recalibration
is then required to determine a new Y value.
In this direct final action, the majority of the revised rule
provisions pertaining to gas flow meters can be found in sections 5.1.5
and 9.2 of appendix K. Minor revisions to sections 7.2.3 and 7.2.5,
Figure K-1, and Table K-1 are being made to be consistent with the
changes to sections 5.1.5 and 9.2. In several other places throughout
part 75 and in the definition of ``Sorbent trap monitoring system'' in
part 72, the term ``dry gas meter,'' when used in reference to a
sorbent trap monitoring system, is being replaced with the more general
term ``gas flow meter.'' Revisions to section 1.5.2 of appendix B of
part 75 will require the gas flow meter calibration procedures and
protocols for periodic recalibration of reference gas flow meters to be
included in the QA plan for the affected unit.
This direct final action, which approves the use of two optional
methods (Methods 30A and 30B) for determining total vapor phase Hg
emissions from stationary sources, is being taken in response to
numerous public comments concerning the desirability of allowing the
use of these types of methods to comply with the Hg emission monitoring
requirements of the CAMR for electric utility steam generating units.
In the May 18, 2005 final rule (70 FR 28636), we summarized the public
comments that we received regarding the use of an instrumental method
as an alternative to the Ontario Hydro Method specified in the proposed
CAMR. As noted earlier in this preamble, the commenters primarily
objected to the required use of the Ontario Hydro Method as the
reference method for the RATAs of Hg monitoring systems and expressed
concern about the complexities in the method and the amount of time
that is required to perform the testing and to receive the results.
Commenters pointed out that it could take days to complete the testing
and weeks to receive the results from a laboratory. Commenters claimed
that for the cap and trade program proposed under CAMR, these delays
could lead to significant implementation problems with respect to the
timely reporting of emissions data. Further, if a RATA should be failed
or invalidated (e.g., if fewer than nine test runs meet the relative
deviation criterion for the paired Ontario Hydro trains), data from the
Hg monitoring system would be invalidated from the hour of the failed
or invalidated test until the hour of completion of a successful RATA.
Conservatively high substitute data values would have to be reported
during that entire time period. In our response to those comments in
the final CAMR rule, we stated that the alternative use of an
instrumental method for the required RATAs of Hg monitoring systems and
sorbent trap monitoring systems is allowed by the final rule but is
subject to approval by the Administrator. We also stated our commitment
to propose and promulgate a Hg instrumental reference method once
sufficient supporting field test data become available. We further
stated that ``A Hg instrumental reference method for RATA testing is
vastly preferable to the Ontario Hydro Method and will greatly
facilitate the implementation of a Hg cap-and-trade program.''
Since promulgation of CAMR, we have continued to communicate with
stakeholders interested in the Hg monitoring requirements of the rule,
and we have come to more clearly understand that it is of great
interest to the affected entities to have additional reference method
options available for relative accuracy testing of installed Hg
monitoring systems as soon as possible. Accordingly, at the end of
2005, we began developing an instrumental test method for Hg and
solicited feedback from the stakeholders on a working draft of the
method (referred to as PRE-009 at http://www.epa.gov/ttn/emc/prelim.html
). More recently, we have been developing a viable sorbent
trap reference method. These efforts have resulted in Methods 30A and
30B.
The general beneficial impacts of this direct final rule to approve
the two optional Hg test methods and amend targeted portions of 40 CFR
parts 72 and 75 include: Allowing affected sources to choose the use of
an alternative to the Ontario Hydro Method without the administrative
burden of applying for Administrator approval on a case-by-case basis;
providing the availability of real-time RATA results (Method 30A);
reducing the overall RATA testing times; reducing costs relative to the
Ontario Hydro Method; and providing additional flexibility in appendix
K sorbent trap monitoring and backup monitoring approaches. The two
optional methods being approved by this direct final rule are
considered to be comparable to the Ontario Hydro Method in terms of the
quality of the results produced. Over the last year, EPA has
collaborated with EPRI and some of its members in a number of field
test programs that have confirmed that the instrumental reference
method approved/established in this notice will provide data comparable
to or better
[[Page 51500]]
than that of the ``Ontario Hydro Method.''
Assuming we do not receive adverse comment on this direct final
rulemaking and Methods 30A and 30B become final, we plan to post
information relevant to Method 30A and 30B applications and equipment
advances on EPA's Web site at http://www.epa.gov/airmarkets.
VII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
This action is not a ``significant regulatory action'' under the
terms of Executive Order (EO) 12866 (58 FR 51735, October 4, 1993) and
is therefore not subject to review under the EO.
B. Paperwork Reduction Act
This action does not impose an information collection burden under
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
Burden means the total time, effort, or financial resources expended by
persons to generate, maintain, retain, or disclose or provide
information to or for a Federal agency. This includes the time needed
to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information, unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
For purposes of assessing the impacts of today's rule on small
entities, small entity is defined as: (1) A small business whose parent
company has fewer than 100 or 1,000 employees, or fewer than 4 billion
kilowatt-hr per year of electricity usage, depending on the size
definition for the affected North American Industry Classification
System code; (2) a small governmental jurisdiction that is a government
of a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise which is independently owned and operated
and is not dominant in its field.
After considering the economic impacts of today's direct final rule
on small entities, I certify that this action will not have a
significant economic impact on a substantial number of small entities.
This direct final rule will not impose any requirements on small
entities because it does not impose any additional regulatory
requirements, but rather provides clarification and additional
regulatory flexibilty.
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Pub.
L. 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective, or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
EPA has determined that this direct final rule does not contain a
Federal mandate that may result in expenditures of $100 million or more
for State, local, and tribal governments in the aggregate, or to the
private sector in any 1 year, nor does this rule significantly or
uniquely impact small governments, because it contains no requirements
that impose new obligations upon them. Thus, this direct final rule is
not subject to the requirements of sections 202 and 205 of the UMRA.
E. Executive Order 13132: Federalism
Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that 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.''
This direct final rule 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, as specified in Executive Order 13132. The use of these
methods is optional on the part of the regulated entities listed. Thus,
Executive Order 13132 does not apply to this direct final rule.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by tribal officials in the development of regulatory
policies that have tribal implications.'' This direct final rule does
not have tribal implications, as specified in Executive Order 13175. It
will not have substantial direct effects on tribal governments, on the
[[Page 51501]]
relationship between the Federal government and Indian tribes, or on
the distribution of power and responsibilities between the Federal
government and Indian tribes. Thus, Executive Order 13175 does not
apply to this final rule.
G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
Executive Order 13045: ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) Is determined to be ``economically significant''
as defined under Executive Order 12866, and (2) concerns an
environmental health or safety risk that EPA has reason to believe may
have a disproportionate effect on children. If the regulatory action
meets both criteria, the Agency must evaluate the environmental health
or safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency. EPA
interprets Executive Order 13045 as applying only to those regulatory
actions that are based on health or safety risks, such that the
analysis required under section 5-501 of the Order has the potential to
influence the regulation. This rule is not subject to Executive Order
13045 because it does not establish an environmental standard intended
to mitigate health or safety risks.
H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This rule is not subject to Executive Order 13211, ``Actions
Concerning Regulations That Significantly Affect Energy Supply,
Distribution, or Use'' (66 FR 28355, May 22, 2001) because it is not a
significant regulatory action under Executive Order 12866.
I. National Technology Transfer Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law No. 104-113, section 12(d) (15 U.S.C.
272 note) directs EPA to use voluntary consensus standards in its
regulatory activities unless to do so would be inconsistent with
applicable law or otherwise impractical. Voluntary consensus standards
are technical standards (e.g., materials specifications, test methods,
sampling procedures, and business practices) that are developed or
adopted by voluntary consensus standards bodies. The NTTAA directs EPA
to provide Congress, through OMB, explanations when the Agency decides
not to use available and applicable voluntary consensus standards. This
rulemaking involves technical standards. Consistent with the NTTAA, EPA
in a previous related rulemaking (70 FR 28606, May 18, 2005) identified
an acceptable VCS for measuring Hg emissions. The standard ASTM D6784-
02, Standard Test Method for Elemental, Oxidized, Particle-Bound and
Total Mercury Gas Generated from Coal-Fired Stationary sources (Ontario
Hydro Method) was cited in that final rule for measuring Hg emissions.
After today's action becomes effective, the Ontario Hydro Method will
remain an acceptable method for measuring Hg emissions.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
Executive Order 12898 (59 FR 7629 (Feb. 16, 1994)) establishes
federal executive policy on environmental justice. Its main provision
directs federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
EPA has determined that this direct final rule 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 direct final rule does not affect or relax the
control measures on sources impacted by this rule and therefore will
not cause emissions increases from these sources.
K. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the Agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA will submit a report containing this rule and other
required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective on November 6, 2007.
List of Subjects
40 CFR Part 60
Environmental protection, Administrative practice and procedures,
Air pollution control, Continuous emission monitors, Electric
utilities, Mercury, Test methods and procedures.
40 CFR Part 72
Environmental protection, Administrative practice and procedures,
Air pollution control, Continuous emission monitors, Electric
utilities, Mercury, Test methods and procedures.
40 CFR Part 75
Environmental protection, Administrative practice and procedures,
Air pollution control, Continuous emission monitors, Electric
utilities, Mercury, Test methods and procedures.
Dated: August 17, 2007.
Stephen L. Johnson,
Administrator.
0
For the reasons set out in the preamble, title 40, chapter I, parts 60,
72, and 75 of the Code of Federal Regulations are 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.
Appendix A-8 [Amended]
0
2. Amend Appendix A-8 by revising the heading and adding in numerical
order Methods 30A and 30B to read as follows:
APPENDIX A-8 TO PART 60--TEST METHODS 26 THROUGH 30B
* * * * *
Method 30A--Determination of Total Vapor Phase Mercury Emissions From
Stationary Sources (Instrumental Analyzer Procedure)
1.0 Scope and Application
What Is Method 30A?
Method 30A is a procedure for measuring total vapor phase
mercury (Hg) emissions from stationary sources using an instrumental
analyzer. This method is particularly appropriate for performing
emissions testing and for conducting relative accuracy test audits
(RATAs) of mercury continuous emissions monitoring systems (Hg CEMS)
and sorbent trap monitoring systems at coal-fired combustion
sources. Quality assurance and quality control
[[Page 51502]]
requirements are included to assure that you, the tester, collect
data of known and acceptable quality for each testing site. This
method does not completely describe all equipment, supplies, and
sampling procedures and analytical procedures you will need but
refers to other test methods for some of the details. Therefore, to
obtain reliable results, you should also have a thorough knowledge
of these additional methods which are also found in appendices A-1
and A-3 to this part:
(a) Method 1--Sample and Velocity Traverses for Stationary
Sources.
(b) Method 4--Determination of Moisture Content in Stack Gases.
1.1 Analytes. What does this method determine? This method is
designed to measure the mass concentration of total vapor phase Hg
in flue gas, which represents the sum of elemental Hg (Hg\0\) and
oxidized forms of Hg (Hg+\2\), in mass concentration
units of micrograms per cubic meter ([mu]g/m\3\).
------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Elemental Hg (Hg\0\).............. 7439-97-6 Typically < 2% of
Calibration Span.
Oxidized Hg (Hg+\2\).............. .............. (Same).
------------------------------------------------------------------------
1.2 Applicability. When is this method required? Method 30A is
offered as a reference method for emission testing and for RATAs of
Hg CEMS and sorbent trap monitoring systems at coal-fired boilers.
Method 30A may also be specified for other source categories in the
future, either by New Source Performance Standards (NSPS), National
Emission Standards for Hazardous Air Pollutants (NESHAP), emissions
trading programs, State Implementation Plans (SIP), or operating
permits that require measurement of Hg concentrations in stationary
source emissions to determine compliance with an applicable emission
standard or limit, or to conduct RATAs of Hg CEMS and sorbent trap
monitoring systems.
1.3 Data Quality Objectives (DQO). How good must my collected
data be? Method 30A has been designed to provide data of high and
known quality for Hg emission testing and for relative accuracy
testing of Hg monitoring systems including Hg CEMS and sorbent trap
monitoring systems. In these and other applications, the principle
objective is to ensure the accuracy of the data at the actual
emission levels encountered. To meet this objective, calibration
standards prepared according to an EPA traceability protocol must be
used and measurement system performance tests are required.
2.0 Summary of Method
In this method, a sample of the effluent gas is continuously
extracted and conveyed to an analyzer capable of measuring the total
vapor phase Hg concentration. Elemental and oxidized mercury (i.e.,
Hg\0\ and Hg+\2\) may be measured separately or
simultaneously but, for purposes of this method, total vapor phase
Hg is the sum of Hg\0\ and Hg+\2\. You must meet the
performance requirements of this method (i.e., system calibration,
interference testing, dynamic spiking, and system integrity/drift
checks) to validate your data. The dynamic spiking requirement is
deferred until January 1, 2009.
3.0 Definitions
3.1 Calibration Curve means the relationship between an
analyzer's response to the injection of a series of calibration
gases and the actual concentrations of those gases.
3.2 Calibration Gas means a gas standard containing Hg\0\ or
HgCl2 at a known concentration that is produced and
certified in accordance with an EPA traceability protocol for
certification of Hg calibration standards.
3.2.1 Zero Gas means a calibration gas with a concentration that
is below the level detectable by the measurement system.
3.2.2 Low-Level Gas means a calibration gas with a concentration
that is 10 to 30 percent of the calibration span.
3.2.3 Mid-Level Gas means a calibration gas with a concentration
that is 40 to 60 percent of the calibration span.
3.2.4 High-Level Gas means a calibration gas whose concentration
is equal to the calibration span.
3.3 Converter means a device that reduces oxidized mercury
(Hg+\2\) to elemental mercury (Hg\0\).
3.4 Calibration Span means the upper limit of valid instrument
response during sampling. To the extent practicable the measured
emissions are to be between 10 and 100 percent of the selected
calibration span (i.e., the measured emissions should be within the
calibrated range determined by the Low- and High-Level gas
standards). It is recommended that the calibration span be at least
twice the native concentration to accommodate the dynamic spiking
procedure.
3.5 Centroidal Area means the central area that has the same
shape as the stack or duct cross section and is no greater than one
percent of the stack or duct total cross-sectional area.
3.6 Data Recorder means the equipment that permanently records
the concentrations reported by the analyzer.
3.7 Drift Check means the test to determine the difference
between the measurement system readings obtained in a post-run
system integrity check and the prior pre-run system integrity check
at a specific calibration gas concentration level (i.e., zero, mid-
level, or high-level).
3.8 Dynamic Spiking means a procedure in which a known mass or
concentration of vapor phase HgCl2 is injected into the
probe sample gas stream at a known flow rate, in order to assess the
effects of the flue gas matrix on the accuracy of the measurement
system.
3.9 Gas Analyzer means the equipment that detects the total
vapor phase Hg being measured and generates an output proportional
to its concentration.
3.10 Interference Test means the test to detect analyzer
responses to compounds other than Hg, usually gases present in the
measured gas stream, that are not adequately accounted for in the
calibration procedure and may cause measurement bias.
3.11 Measurement System means all of the equipment used to
determine the Hg concentration. The measurement system may generally
include the following major subsystems: sample acquisition,
Hg+2 to Hg0 converter, sample transport,
sample conditioning, flow control/gas manifold, gas analyzer, and
data recorder.
3.12 Native Concentration means the total vapor phase Hg
concentration in the effluent gas stream.
3.13 NIST means the National Institute of Standards and
Technology, located in Gaithersburg, Maryland.
3.14 Response Time means the time it takes for the measurement
system, while operating normally at its target sample flow rate or
dilution ratio, to respond to a known step change in gas
concentration (from a low-level to a high-level gas) and to read
within 5 percent of the stable high-level gas response.
3.15 Run means a series of gas samples taken successively from
the stack or duct. A test normally consists of a specific number of
runs.
3.16 System Calibration Error means the difference between the
measured concentration of a low-, mid-, or high-level Hg\0\
calibration gas and the certified concentration of the gas when it
is introduced in system calibration mode.
3.17 System Calibration Mode means introducing the calibration
gases into the measurement system at the probe, upstream of all
sample conditioning components.
3.18 Test refers to the series of runs required by the
applicable regulation.
4.0 Interferences
Interferences will vary among instruments and potential
instrument-specific spectral and matrix interferences must be
evaluated through the interference test and the dynamic spiking
tests.
5.0 Safety
What safety measures should I consider when using this method?
This method may require you to work with hazardous materials and
in hazardous conditions. You are encouraged to establish safety
procedures before using the method. Among other precautions, you
should become familiar with the safety recommendations in the gas
analyzer user's manual. Occupational Safety and Health
Administration (OSHA) regulations concerning use of compressed gas
cylinders and noxious gases may apply.
[[Page 51503]]
6.0 Equipment and Supplies
6.1 What do I need for the measurement system? This method is
intended to be applicable to multiple instrumental technologies. You
may use any equipment and supplies that meet the following
specifications.
6.1.1 All wetted sampling system components, including probe
components prior to the point at which the calibration gas is
introduced, must be chemically inert to all Hg species. Materials
such as perfluoroalkoxy (PFA) Teflon\TM\, quartz, treated stainless
steel (SS) are examples of such materials. [Note: These materials of
construction are required because components prior to the
calibration gas injection point are not included in the system
calibration error, system integrity, and interference tests.]
6.1.2 The interference, system calibration error, system
integrity, drift and dynamic spiking test criteria must all be met
by the system used.
6.1.3 The system must be capable of measuring and controlling
sample flow rate.
6.1.4 All system components prior to the Hg+\2\ to
Hg\0\ converter must be maintained at a sample temperature above the
acid gas dew point.
6.2 Measurement System Components. Figure 30A-1 in Section 17.0
is an example schematic of a Method 30A measurement system.
6.2.1 Sample Probe. The probe must be made of the appropriate
materials as noted in Section 6.1.1, heated when necessary (see
Section 6.1.4), configured with ports for introduction of
calibration and spiking gases, and of sufficient length to traverse
all of the sample points.
6.2.2 Filter or Other Particulate Removal Device. The filter or
other particulate removal device is considered to be a part of the
measurement system, must be made of appropriate materials as noted
in Section 6.1.1, and must be included in all system tests.
6.2.3 Sample Line. The sample line that connects the probe to
the converter, conditioning system and analyzer must be made of
appropriate materials as noted in Section 6.1.1.
6.2.4 Conditioning Equipment. For dry basis measurements, a
condenser, dryer or other suitable device is required to remove
moisture continuously from the sample gas. Any equipment needed to
heat the probe, or sample line to avoid condensation prior to the
moisture removal component is also required. For wet basis systems,
you must keep the sample above its dew point either by: (1) Heating
the sample line and all sample transport components up to the inlet
of the analyzer (and, for hot-wet extractive systems, also heating
the analyzer) or (2) by diluting the sample prior to analysis using
a dilution probe system. The components required to do either of the
above are considered to be conditioning equipment.
6.2.5 Sampling Pump. A pump is needed to push or pull the sample
gas through the system at a flow rate sufficient to minimize the
response time of the measurement system. If a mechanical sample pump
is used and its surfaces are in contact with the sample gas prior to
detection, the pump must be leak free and must be constructed of a
material that is non-reactive to the gas being sampled (see Section
6.1.1). For dilution-type measurement systems, an ejector pump
(eductor) may be used to create a sufficient vacuum that sample gas
will be drawn through a critical orifice at a constant rate. The
ejector pump may be constructed of any material that is non-reactive
to the gas being sampled.
6.2.6 Calibration Gas System(s). One or more systems may be
needed to introduce calibration gases into the measurement system. A
system should be able to flood the sampling probe sufficiently to
prevent entry of gas from the effluent stream.
6.2.7 Dynamic Spiking Port. For the purposes of the dynamic
spiking procedure described in Section 8.2.7, the measurement system
must be equipped with a port to allow introduction of the dynamic
spike gas stream with the sample gas stream, at a point as close as
possible to the inlet of the probe so as to ensure adequate mixing.
The same port used for system calibrations and calibration error
checks may be used for dynamic spiking purposes.
6.2.8 Sample Gas Delivery. The sample line may feed directly to
a converter, to a by-pass valve (for speciating systems), or to a
sample manifold. All valve and/or manifold components must be made
of material that is non-reactive to the gas sampled and the
calibration gas, and must be configured to safely discharge any
excess gas.
6.2.9 Hg Analyzer. An instrument is required that continuously
measures the total vapor phase Hg in the gas stream and meets the
applicable specifications in Section 13.0.
6.2.10 Data Recorder. A recorder, such as a computerized data
acquisition and handling system (DAHS), digital recorder, strip
chart, or data logger, is required for recording measurement data.
6.3 Moisture Measurement System. If correction of the measured
Hg emissions for moisture is required (see Section 8.5), either
Method 4 in appendix A-3 to this part or other moisture measurement
methods approved by the Administrator will be needed to measure
stack gas moisture content.
7.0 Reagents and Standards
7.1 Calibration Gases. What calibration gases do I need? You
will need calibration gases of known concentrations of Hg\0\ and
HgCl2. Special reagents and equipment may be required to
prepare the HgCl\2\ gas standards (e.g., a NIST-traceable solution
of HgCl2 and a gas generator equipped with mass flow
controllers).
The following calibration gas concentrations are required:
7.1.1 High-Level Gas. Equal to the selected calibration span.
7.1.2 Mid-Level Gas. 40 to 60 percent of the calibration span.
7.1.3 Low-Level Gas. 10 to 30 percent of the calibration span.
7.1.4 Zero Gas. No detectable Hg.
7.1.5 Dynamic Spike Gas. The exact concentration of the
HgCl2 calibration gas used to perform the pre-test
dynamic spiking procedure described in Section 8.2.7 depends on the
native Hg concentration in the stack The spike gas must produce a
spiked sample concentration above the native concentration, as
specified in Section 8.2.7.2.2.
7.2 Interference Test. What reagents do I need for the
interference test? Use the appropriate test gases listed in Table
30A-3 in Section 17.0 (i.e., the potential interferents for the
source to be tested, as identified by the instrument manufacturer)
to conduct the interference check. These gases need not be of
protocol gas quality.
8.0 Sample Collection
Emission Test Procedure
Figure 30A-2 in Section 17.0 presents an overview of the test
procedures required by this method. Since you may choose different
options to comply with certain performance criteria, you must
identify the specific options and associated frequencies you select
and document your results in regard to the performance criteria.
8.1 Sample Point Selection. What sampling site and sampling
points do I select?
8.1.1 When this method is used solely for Hg emission testing
(e.g., to determine compliance with an emission standard or limit),
use twelve sampling points located according to Table 1-1 or Table
1-2 of Method 1 in appendix A-1 to this part. Alternatively, you may
conduct a stratification test as described in Section 8.1.3 to
determine the number and location of the sampling points.
8.1.2 When this method is used for relative accuracy testing of
a Hg CEMS or sorbent trap monitoring system, follow the sampling
site selection and sampling point layout procedures for gas monitor
RATA testing described in the appropriate performance specification
or applicable regulation (e.g., Performance Specification 2, section
8.1.3 of appendix B to this part or section 6.5.6 of appendix A to
part 75 of this chapter), with one exception. If you elect to
perform stratification testing as part of the sampling point
selection process, perform the testing in accordance with Section
8.1.3 of this method (see also ``Summary Table of QA/QC
Requirements'' in Section 9.0).
8.1.3 Determination of Stratification. If you elect to perform
stratification testing as part of the sampling point selection
process and the test results show your effluent gas stream to be
unstratified or minimally stratified, you may be allowed to sample
at fewer points or at different points than would otherwise be
required.
8.1.3.1 Test Procedure. To test for stratification, use a probe
of appropriate length to measure the total vapor phase Hg
concentration at twelve traverse points located according to Table
1-1 or Table 1-2 of Method 1 in appendix A-1 to this part.
Alternatively, for a sampling location where stratification is
expected (e.g., after a wet scrubber or at a point where dissimilar
gas streams are combined together), if a 12-point Hg stratification
test has been previously performed at that location and the results
of the test showed the location to be minimally stratified or
unstratified according to the criteria in section 8.1.3.2, you may
perform an abbreviated 3-point or 6-point Hg stratification test at
the points specified in
[[Page 51504]]
section 6.5.6.2(a) of appendix A to part 75 of this chapter in lieu
of performing the 12-point test. Sample for a minimum of twice the
system response time (see Section 8.2.6) at each traverse point.
Calculate the individual point and mean Hg concentrations.
8.1.3.2 Acceptance Criteria and Sampling Point Location.
8.1.3.2.1 If the Hg concentration at each traverse point differs
from the mean concentration for all traverse points by no more than:
(a) 5 percent of the mean concentration; or (b) 0.2 [mu]g/m\3\ (whichever is less restrictive), the gas stream
is considered to be unstratified and you may collect samples from a
single point that most closely matches the mean.
8.1.3.2.2 If the 5 percent or 0.2 [mu]g/m\3\ criterion in
Section 8.1.3.2.1 is not met, but the Hg concentration at each
traverse point differs from the mean concentration for all traverse
points by no more than: (a)10 percent of the mean; or
(b)0.5 [mu]g/m\3\ (whichever is less restrictive), the
gas stream is considered to be minimally stratified, and you may
take samples from three points, provided the points are located on
the measurement line exhibiting the highest average Hg concentration
during the stratification test. If the stack diameter (or equivalent
diameter, for a rectangular stack or duct) is greater than 2.4
meters (7.8 ft), locate the three sampling points at 0.4, 1.0, and
2.0 meters from the stack or duct wall. Alternatively, if a RATA
required by part 75 of this chapter is being conducted, you may
locate the three points at 4.4, 14.6, and 29.6 percent of the duct
diameter, in accordance with Method 1 in appendix A-1 to this part.
For stack or duct diameters of 2.4 meters (7.8 ft) or less, locate
the three sampling points at 16.7, 50.0, and 83.3 percent of the
measurement line.
8.1.3.2.3 If the gas stream is found to be stratified because
the 10 percent or 0.5 [mu]g/m\3\ criterion in Section 8.1.3.2.2 is
not met, then either locate three sampling points at 16.7, 50.0, and
83.3 percent of the measurement line that exhibited the highest
average Hg concentration during the stratification test, or locate
twelve traverse points for the test in accordance with Table 1-1 or
Table 1-2 of Method 1 in appendix A-1 to this part; or, if a RATA
required by part 75 of this chapter is being conducted, locate six
Method 1 points along the measurement line that exhibited the
highest average Hg concentration.
8.1.3.3 Temporal Variations. Temporal variations in the source
Hg concentration during a stratification test may complicate the
determination of stratification. If temporal variations are a
concern, you may use the following procedure to normalize the
stratification test data. A second Hg measurement system, i.e.,
either an installed Hg CEMS or another Method 30A system, is
required to perform this procedure. Position the sampling probe of
the second Hg measurement system at a fixed point in the stack or
duct, at least one meter from the stack or duct wall. Then, each
time that the Hg concentration is measured at one of the
stratification test points, make a concurrent measurement of Hg
concentration at the fixed point. Normalize the Hg concentration
measured at each traverse point, by multiplying it by the ratio of
CF,avg to CF, where CF is the
corresponding fixed-point Hg concentration measurement, and
CF,avg is the average of all of the fixed-point
measurements over the duration of the stratification test. Evaluate
the results of the stratification test according to section 8.1.3.2,
using the normalized Hg concentrations.
8.1.3.4 Stratification Testing Exemption. Stratification testing
need not be performed at a test location where it would otherwise be
required to justify using fewer sample points or different sample
points, if the owner or operator documents that the Hg concentration
in the stack gas is expected to be 3 [mu]g/m\3\ or less at the time
of a Hg monitoring system RATA or an Hg emissions test. To
demonstrate that a particular test location qualifies for the
stratification testing exemption, representative Hg emissions data
must be collected just prior to the RATA or emissions test. At least
one hour of Hg concentration data is required for the demonstration.
The data used for the demonstration shall be recorded at process
operating conditions that closely approximate the operating
conditions that will exist during the RATA or emissions test. It is
recommended that collection of the demonstration data be integrated
with the on-site pretest procedures required by the reference method
being used for the RATA or emissions test (whether this method or
another approved Hg reference method is used). Quality-assured data
from an installed Hg monitoring system may also be used for the
demonstration. If a particular test location qualifies for the
stratification testing exemption, sampling shall be performed at
three points, as described in section 8.1.3.2.2 of this method. The
owner or operator shall fully document the method used to collect
the demonstration data and shall keep this documentation on file
with the data from the associated RATA or Hg emissions test.
8.1.3.5 Interim Alternative Stratification Test Procedures. In
the time period between the effective date of this method and
January 1, 2009, you may follow one of the following two procedures.
Substitute a stratification test for sulfur dioxide (SO2)
for the Hg stratification test described in section 8.1.3.1. If this
option is chosen, follow the test procedures in section 6.5.6.1 of
appendix A to part 75 of this chapter. Evaluate the test results and
determine the sampling point locations according to section 6.5.6.3
of appendix A to part 75 of this chapter. If the sampling location
is found to be minimally stratified or unstratified for
SO2, it shall be considered minimally stratified or
unstratified for Hg. Alternatively, you may forgo stratification
testing, assume the gas stream is minimally stratified, and sample
at three points as described in section 8.1.3.2.2 of this method.
8.2 Initial Measurement System Performance Tests. What initial
performance criteria must my system meet before I begin sampling?
Before measuring emissions, perform the following procedures:
(a) Interference Test;
(b) Calibration Gas Verification;
(c) Measurement System Preparation;
(d) 3-Point System Calibration Error Test;
(e) System Integrity Check;
(f) Measurement System Response Time Test; and
(g) Dynamic Spiking Test.
8.2.1 Interference Test (Optional). Your measurement system
should be free of known interferences. It is recommended that you
conduct this interference test of your measurement system prior to
its initial use in the field to verify that the candidate test
instrument is free from inherent biases or interferences resulting
from common combustion emission constituents. If you have multiple
measurement systems with components of the same make and model
numbers, you need only perform this interference check on one system
and you may also rely on an interference test conducted by the
manufacturer on a system having components of the same make and
model(s) of the system that you use. The interference test procedure
is found in Section 8.6 of this method.
8.2.2 Calibration Gas Verification. How must I verify the
concentrations of my calibration gases?
8.2.2.1 Cylinder Gas Standards. When cylinder gas standards are
used for Hg0, obtain a certificate from the gas
manufacturer and confirm that the documentation includes all
information required by an EPA traceability protocol (see Section
16). Confirm that the manufacturer certification is complete and
current. Ensure that the calibration gas certifications have not
expired.
8.2.2.2 Other Calibration Standards. All other calibration
standards for HgCl2 and Hg0, such as gas
generators, must meet the requirements of an EPA traceability
protocol (see Section 16), and the certification procedures must be
fully documented in the test report.
8.2.2.3 Calibration Span. Select the calibration span (i.e.,
high-level gas concentration) so that the measured source emissions
are 10 to 100 percent of the calibration span. This requirement is
waived for applications in which the Hg concentrations are
consistently below 1 [mu]g/m\3\; however, the calibration span for
these low-concentration applications shall not exceed 5 [mu]g/m\3\.
8.2.3 Measurement System Preparation. How do I prepare my
measurement system for use? Assemble, prepare, and precondition the
measurement system according to your standard operating procedure.
Adjust the system to achieve the correct sampling rate or dilution
ratio (as applicable). Then, conduct a 3-point system calibration
error test using Hg0 as described in Section 8.2.4, an
initial system integrity check using HgCl2 and a zero gas
as described in Section 8.2.5, and a pre-test dynamic spiking test
as described in Section 8.2.7.
8.2.4 System Calibration Error Test. Conduct a 3-point system
calibration error test before the first test run. Use Hg\0\
standards for this test. Introduce the low-, mid-, and high-level
calibration gases in any order, in system calibration mode, unless
you desire to determine the system response time during this test,
in which case, inject the gases such that the high-level injection
[[Page 51505]]
directly follows the low-level injection. 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 calibration error checks, and you may make only the
adjustments necessary to maintain the proper ratio. After each gas
injection, wait until a stable response has been obtained. Record
the analyzer's final, stable response to each calibration gas on a
form similar to Table 30A-1 in Section 17.0. For each calibration
gas, calculate the system calibration error using Equation 30A-1 in
Section 12.2. The calibration error specification in Section 13.1
must be met for the low-, mid-, and high-level gases. If the
calibration error specification is not met for all three gases, take
corrective action and repeat the test until an acceptable 3-point
calibration is achieved.
8.2.5 System Integrity Check. Perform a two-point system
integrity check before the first test run. Use the zero gas and
either the mid- or high-level HgCl2 calibration gas for
the check, whichever one best represents the total vapor phase Hg
concentration levels in the stack. Record the data on a form similar
to Table 30A-2 in Section 17.0. The system integrity check
specification in Section 13.2 must be met for both the zero gas and
the mid- or high-level gas. If the system integrity specification is
not met for both gases, take corrective action and repeat the test
until an acceptable system integrity check is achieved.
8.2.6 Measurement System Response Time. The measurement system
response time is used to determine the minimum sampling time for
each sampling point and is equal to the time that is required for
the measured Hg concentration to increase from the stable low-level
calibration gas response to a value within 5 percent of the stable
high-level calibration gas response during the system calibration
error test in Section 8.2.4. Round off the measured system response
time to the nearest minute.
8.2.7 Dynamic Spiking Test. You must perform dynamic spiking
prior to the first test run to validate your test data. The purpose
of this procedure is to demonstrate that the site-specific flue gas
matrix does not adversely affect the accuracy of the measurement
system. The specifications in Section 13.5 must be met to validate
your data. If these specifications are not met for the pre-test
dynamic spiking, you may not proceed with the test until
satisfactory results are obtained. For the time period between the
effective date of this method and January 1, 2009, the dynamic
spiking requirement is waived.
8.2.7.1 How do I perform dynamic spiking? Dynamic spiking is a
gas phase application of the method of standard additions, which
involves injecting a known quantity of Hg into the measurement
system upstream of all sample conditioning components, similar to
system calibration mode, except the probe is not flooded and the
resulting sample stream includes both effluent gas and the spike
gas. You must follow a written procedure that details how the spike
is added to the system, how the spike dilution factor (DF) is
measured, and how the Hg concentration data are collected and
processed.
8.2.7.2 Spiking Procedure Requirements.
8.2.7.2.1 Spiking Gas Requirements. The spike gas must also be a
HgCl2 calibration gas certified by an EPA traceability
protocol. You must choose concentrations that can produce the target
levels while being injected at a volumetric flow rate that is < =20
percent of the total volumetric flow rate through the measurement
system (i.e., sample flow rate plus spike gas flow rate).
8.2.7.2.2 Target Spiking Level. The target level for spiking
must be 150 to 200 percent of the native Hg concentration; however,
if the native Hg concentration is < 1 [mu]g/m\3\, set the target
level to add between 1 and 4 [mu]g/m\3\ Hg+\2\ to the
native concentration. Use Equation 30A-5 in Section 12.5 to
calculate the acceptable range of spike gas concentrations at the
target level. Then select a spike gas concentration in that range.
8.2.7.2.3 Spike Injections. You must inject spikes in such a
manner that the spiking does not alter the total volumetric sample
system flow rate and dilution ratio (if applicable). You must
collect at least 3 data points, and the relative standard deviation
(RSD) specification in Section 13.5 must be met. Each data point
represents a single spike injection, and pre- and post-injection
measurements of the native Hg concentration (or diluted native
concentration, as applicable) are required for each spike injection.
8.2.7.2.4 Spike Dilution Factor (DF). For each spike injection,
DF, the dilution factor must be determined. DF is the ratio of the
total volumetric flow rate of gas through the measurement system to
the spike gas flow rate. This factor must be >=5. The spiking mass
balance calculation is directly dependent on the accuracy of the DF
determination. As a result, high accuracy total volumetric flow rate
and spike gas flowrate measurements are required. These flow rates
may be determined by direct or indirect measurement. Calibrated flow
meters, venturies, orifices or tracer gas measurements are examples
of potential flow measurement techniques.
8.2.7.2.5 Concentrations. The measurement system must record
total vapor phase Hg concentrations continuously during the dynamic
spiking procedure. It is possible that dynamic spiking at a level
close to 200 percent of the native Hg concentration may cause the
measured Hg concentration to exceed the calibration span value.
Avoid this by choosing a lower spiking level or by recalibration at
a higher span. The measurements shall not exceed 120 percent of the
calibration span. The ``baseline'' measurements made between spikes
may represent the native Hg concentration (if spike gas flow is
stopped between injections) or the native Hg concentration diluted
by blank or carrier gas flowing at the same rate as the spike gas
(if gas flow cannot be stopped between injections). Each baseline
measurement must include at least 4 readings or 1 minute (whichever
is greater) of stable responses. Use Equation 30A-10 or 30A-11 in
Section 12.10 (as applicable) to convert baseline measurements to
native concentration.
8.2.7.2.6 Recovery. Calculate spike recoveries using Equation
30A-7 in Section 12.7. Mass recoveries may be calculated from stable
responses based on injected mass flows or from integrated response
peaks based on total mass injected. Calculate the mean and RSD for
the three (or more) spike injections and compare to the
specifications in Section 13.5.
8.2.7.2.7 Error Adjustment Option. You may adjust the
measurement data collected during dynamic spiking for the system
calibration error using Equation 30A-3 in Section 12. To do this,
perform the initial system integrity check prior to the dynamic
spiking test, and perform another system integrity check following
the dynamic spiking test and before the first test run. If you
choose this option, you must apply Equation 30A-3 to both the spiked
sample concentration measurement (Css) and the baseline
or native concentration measurement (Cnative), each
substituted in place of Cavg in the equation.
8.2.7.3 Example Spiking Procedure Using a Hot Vapor Calibration
Source Generator.
(a) Introduce the spike gas into the probe using a hot vapor
calibration source generator and a solution of HgCl2 in
dilute HC1 and HNO3. The calibrator uses a mass flow
controller (accurate within 2 percent) to measure the gas flow, and
the solution feed is measured using a top-loading balance accurate
to 0.01g. The challenges of injecting oxidized Hg may make it
impractical to stop the flow of gas between spike injections. In
this case, operate the hot vapor calibration source generator
continuously during the spiking procedure, swapping blank solutions
for HgCl2 solutions when switching between spiking and
baseline measurements.
(b) If applicable, monitor the measurement system to make sure
the total sampling system flow rate and the sample dilution ratio do
not change during this procedure. Record all data on a data sheet
similar to Table 30A-5 in Section 17.0. If the Hg measurement system
design makes it impractical to measure the total volumetric flow
rate through the system, use a spike gas that includes a tracer for
measuring the dilution factor, DF (see Equation 30A-9 in Section
12.9). Allow the measurements to stabilize between each spike
injection, average the pre- and post-injection baseline
measurements, and calculate the native concentration. If this
measurement shifts by more than 5 percent during any injection, it
may be necessary to discard that data point and repeat the injection
to achieve the required RSD among the injections. If the spikes
persistently show poor repeatability, or if the recoveries are not
within the range specified in Section 13.5, take corrective action.
8.2.8 Run Validation. How do I confirm that each run I conduct
is valid?
8.2.8.1 System Integrity Checks.
(a) Before and after each test run, perform a two-point system
integrity check using the same procedure as the initial system
integrity check described in Section 8.2.5. You may use data from
that initial system integrity
[[Page 51506]]
check as the pre-run data for the first test run, provided it is the
most recent system integrity check done before the first run. You
may also use the results of a successful post-run system integrity
check as the pre-run data for the next test run. Do not make any
adjustments to the measurement system during these checks, other
than to maintain the target calibration gas flow rate and the proper
dilution ratio.
(b) As a time-saving alternative, you may, at the risk of
invalidating multiple test runs, skip one or more integrity checks
during a test day. Provided there have been no auto-calibrations or
other instrument alterations, a single integrity check may suffice
as a post-run check to validate (or invalidate) as many consecutive
test runs as can be completed during a single test day. All
subsequent test days must begin with a pre-run system integrity
check subject to the same performance criteria and corrective action
requirements as a post-run system integrity check.
(c) Each system integrity check must meet the criteria for
system integrity checks in Section 13.2. If a post-run system
integrity check is failed, all test runs since the last passed
system integrity check are invalid. If a post-run or a pre-run
system integrity check is failed, you must take corrective action
and pass another 3-point Hg\0\ system calibration error test
(Section 8.2.4) followed by another system integrity check before
conducting any additional test runs. Record the results of the pre-
and post-run system integrity checks on a form similar to Table 30A-
2 in Section 17.0.
8.2.8.2 Drift Check. Using the data from the successful pre- and
post-run system integrity checks, calculate the zero and upscale
drift, using Equation 30A-2 in Section 12.3. Exceeding the Section
13.3 specification does not invalidate the run, but corrective
action must be taken and a new 3-point Hg\0\ system calibration
error test and a system integrity check must be passed before any
more runs are made.
8.3 Dilution-Type Systems--Special Considerations. When a
dilution-type measurement system is used, there are three important
considerations that must be taken into account to ensure the quality
of the emissions data. First, the critical orifice size and dilution
ratio must be selected properly so that the sample dew point will be
below the sample line and analyzer temperatures. Second, a high-
quality, accurate dilution controller must be used to maintain the
correct dilution ratio during sampling. The dilution controller
should be capable of monitoring the dilution air pressure, orifice
upstream pressure, eductor vacuum, and sample flow rates. Third,
differences between the molecular weight of calibration gas
mixtures, dilution air, and the stack gas molecular weight must be
considered because these can affect the dilution ratio and introduce
measurement bias.
8.4 Sampling.
(a) Position the probe at the first sampling point. Allow the
system to flush and equilibrate for at least two times the
measurement system response time before recording any data. Then,
traverse and record measurements at all required sampling points.
Sample at each traverse point for an equal length of time,
maintaining the appropriate sample flow rate or dilution ratio (as
applicable). For all Hg instrumental method systems, the minimum
sampling time at each sampling point must be at least two times the
system response time, but not less than 10 minutes. For
concentrating systems, the minimum sampling time must also include
at least 4 concentration measurement cycles.
(b) After recording data for the appropriate period of time at
the first traverse point, you may move the sample probe to the next
point and continue recording, omitting the requirement to allow the
system to equilibrate for two times the system response time before
recording data at the subsequent traverse points. You must, however,
sample at this and all subsequent traverse points for the required
minimum amount of time specified in this section. If you must remove
the probe from the stack for any reason, you must again allow the
sampling system to equilibrate for at least two times the system
response time prior to resuming data recording.
(c) If at any point the measured Hg concentration exceeds the
calibration span value, you must at a minimum identify and report
this as a deviation from the method. Depending on the data quality
objectives of the test, this event may require corrective action
before proceeding. If the average Hg concentration for any run
exceeds the calibration span value, the run is invalidated.
8.5 Moisture Correction. If the moisture basis (wet or dry) of
the measurements made with this method is different from the
moisture basis of either: (1) The applicable emission limit; or (2)
a Hg CEMS or sorbent trap monitoring system being evaluated for
relative accuracy, you must determine the moisture content of the
flue gas and correct the measured gas concentrations to a dry basis
using Method 4 in appendix A-3 of this part or other appropriate
methods, subject to the approval of the Administrator.
8.6 Optional Interference Test Procedure.
(a) Select an appropriate calibration span that reflects the
source(s) to be tested and perform the interference check at 40
percent of the lowest calibration span value anticipated, e.g., 10
[mu]g/m\3\. Alternatively, successfully conducting the interference
test at an absolute Hg concentration of 2 [mu]g/m\3\ will
demonstrate performance for an equivalent calibration span of 5
[mu]g/m\3\, the lowest calibration span allowed for Method 30A
testing. Therefore, performing the interference test at the 2 [mu]/
m\3\ level will serve to demonstrate acceptable performance for all
calibration spans greater than or equal to 5 [mu]g/m\3\.
(b) Introduce the interference test gases listed in Table 30A-3
in Section 17.0 into the measurement system separately or as a
mixture. The interference test gases HCl and NO must be introduced
as a mixture. The interference test gases must be introduced into
the sampling system at the probe such that the interference gas
mixtures pass through all filters, scrubbers, conditioners, and
other components as would be configured for normal sampling.
(c) The interference test must be performed using
HgCl2, and each interference test gas (or gas mixture)
must be evaluated in triplicate. This is accomplished by measuring
the Hg response first with only the HgCl2 gas present and
then when adding the interference test gas(es) while maintaining the
HgCl2 concentration of the test stream constant. It is
important that the equipment used to conduct the interference test
be of sufficient quality so as to be capable of blending the
HgCl2 and interference gases while maintaining the Hg
concentration constant. Gas blending system or manifolds may be
used.
(d) The duration of each test should be for a sufficient period
of time to ensure the Hg measurement system surfaces are conditioned
and a stable output is obtained. Measure the Hg response of the
analyzer to these gases in [mu]g/m3. Record the responses and
determine the overall interference response using Table 30A-4 in
Section 17.0 and the equations presented in Section 12.11. The
specification in Section 13.4 must be met.
(e) A copy of these data, including the date completed and a
signed certification, must be included with each test report. The
intent of this test is that the interference test results are
intended to be valid for the life of the system. As a result, the Hg
measurement system should be operated and tested in a configuration
consistent with the configuration that will be used for field
applications. However, if the system used for field testing is not
consistent with the system that was interference-tested, the
interference test must be repeated before it is used for any field
applications. Examples of such conditions include, but are not
limited to: major changes in dilution ratio (for dilution based
systems), changes in catalyst materials, changes in filtering device
design or materials, changes in probe design or configuration, and
changes in gas conditioning materials or approaches.
9.0 Quality Control
What quality control measures must I take?
The table which follows is a summary of the mandatory,
suggested, and alternative quality assurance and quality control
measures and the associated frequency and acceptance criteria. All
of the QC data, along with the run data, must be documented and
included in the test report.
[[Page 51507]]
Summary Table of QA/QC Requirements
----------------------------------------------------------------------------------------------------------------
Status \1\ Process or element QA/QC specification Acceptance criteria Checking frequency
----------------------------------------------------------------------------------------------------------------
S.................. Identify Data User.. .................... Regulatory Agency or Before designing
other primary end user test.
of data.
M.................. Analyzer Design..... Analyzer range...... Sufficiently > high-level ....................
gas to allow
determination of system
calibration error.
S.................. .................... Analyzer resolution < 2.0 % of full-scale Manufacturer design.
or sensitivity. range.
S.................. .................... Interference Overall response < = 3% of
response. calibration span.
Alternatively, overall
response < = 0.3 [mu]g/
m\3\.
M.................. Calibration Gases... Traceability Validation of
protocol. concentration required.
M.................. .................... High-level Hg\0\ gas Equal to the calibration Each calibration
span. error test.
M.................. .................... Mid-level Hg\0\ gas. 40 to 60% of calibration Each calibration
span. error test.
M.................. .................... Low-level Hg\0\ gas. 10 to 30% of calibration Each calibration
span. error test.
M.................. .................... High-level HgCl2 gas Equal to the calibration Each system
span. integrity check (if
it better
represents Cnative
than the mid level
gas).
M.................. .................... Mid-level HgCl2..... 40 to 60% of calibration Each system gas
span. integrity check (if
it better
represents Cnative
than the high level
gas).
M.................. .................... Zero gas............ ......................... Each system
integrity check.
M.................. .................... Dynamic spike gas A high-concentration Pre-test; dynamic
(Cnative >= 1 [mu]g/ HgCl2 gas, used to spiking not
m\3\). produce a spiked sample required until 1/1/
concentration that is 09.
150 to 200% of the
native concentration.
M.................. .................... Dynamic spike gas A high-concentration Pre-test; dynamic
(Cnative < 1 [mu]g/ HgCl2 gas, used to spiking not
m\3\). produce a spiked sample required until 1/1/
concentration that is 1 09.
to 2 [mu]g/m\3\ above
the native concentration.
S.................. Data Recorder Design Data resolution..... < = 0.5% of full-scale.... Manufacturer design.
M.................. Sample Extraction... Probe material...... Inert to sample Each run.
constituents (e.g., PFA
Teflon, or quartz if
stack > 500 [deg]F).
M.................. Sample Extraction... Probe, filter and For dry-basis analyzers, Each run.
sample line keep sample above the
temperature. dew point, by heating
prior to moisture
removal.
For wet-basis analyzers,
keep sample above dew
point at all times, by
heating or dilution.
M.................. Sample Extraction... Calibration valve Inert to sample Each test.
material. constituents (e.g., PFA
Teflon or PFA Teflon
coated).
S.................. Sample Extraction... Sample pump material Inert to sample Each test.
constituents.
M.................. Sample Extraction... Manifold material... Inert to sample Each test.
constituents.
M.................. Particulate Removal. Filter inertness.... Pass calibration error Each calibration
check. error check.
M.................. System Calibration System calibration CE < = 5.0 % of the Before initial run
Performance. error (CE) test. calibration span for the and after a failed
low-, mid-or high-level system integrity
Hg\0\ calibration gas. check or drift
Alternative test.
specification: < = 0.5
[mu]g/m\3\ absolute
difference between
system response and
reference value.
M.................. System Calibration System integrity Error < = 5.0% of the Before initial run,
Performance. check. calibration span for the after each run, at
zero and mid- or high- the beginning of
level HgCl2 calibration subsequent test
gas. days, and after a
Alternative failed system
specification: < = 0.5 integrity check or
[mu]g/m\3\ absolute drift test.
difference between
system response and
reference value.
M.................. System Performance.. System response time Used to determine minimum During initial 3-
sampling time per point. point system
calibration error
test.
M.................. System Performance.. Drift............... < = 3.0% of calibration At least once per
span for the zero and test day.
mid- or high-level gas.
Alternative
specification: < = 0.3
[mu]g/m\3\ absolute
difference between pre-
and post-run system
calibration error
percentages..
M.................. System Performance.. Minimum sampling The greater of two times Each sampling point.
time. the system response time
or 10 minutes.
Concentrating systems
must also include at
least 4 cycles.
M.................. System Performance.. Percentage spike Percentage spike Before initial
recovery and recovery, at the target dynamic spiking not
relative standard level: 100 required until 1/1/
deviation. 10%. 09.
Relative standard
deviation: < = 5 percent.
Alternative
specification: absolute
difference between
calculated and measured
spike values < = 0.5
[mu]g/m\3\.
[[Page 51508]]
M.................. Sample Point Number and Location For emission testing Prior to first run.
Selection. of Sample Points. applications, use 12
points, located
according to Method 1 in
appendix A-1 to this
part, unless the results
of a stratification test
allow fewer points to be
used.
.................... .................... For Part 60 RATAs, follow
the procedures in
Performance
Specification 2, section
8.1.3, and for Part 75
RATAs, follow the
procedures in section
6.5.6 of appendix A to
Part 75. That is:
.................... .................... At any test
location, you may use 3
sample points located at
16.7, 50.0, and 83.3% of
a ``long'' measurement
line passing through the
centroidal area; or
.................... .................... At any test
location, you may use 6
sample points along a
diameter, located
according to Method 1
(Part 75 RATAs, only);
or
.................... .................... At a location
where stratification is
not expected and the
measurement line is >
2.4 m (7.8 ft), you may
use 3 sample points
located along a
``short'' measurement
line at 0.4, 1.0, and
2.0 m from the stack or
duct wall or, for Part
75 only, sample points
may be located at 4.4,
14.6, and 29.6% of the
measurement line; or
.................... .................... After a wet
scrubber or at a point
where dissimilar gas
streams are combined,
either locate 3 sample
points along the
``long'' measurement
line or locate 6 Method
1 points along a
diameter (Part 75,
only), unless the
results of a
stratification test
allow you to use a
``short'' 3-point
measurement line or to
sample at a single point.
.................... .................... If it can be
demonstrated that stack
gas concentration is < =
3 [mu]g/m\3\, then the
test site is exempted
from stratification
testing. Use the 3-point
``short'' measurement
line if the stack
diameter is > 2.4 m (7.8
ft) and the 3-point
``long'' line for stack
diameters < = 2.4 m (7.8
ft).
A.................. Sample Point Stratification Test If the Hg concentration Prior to first run.
Selection. (see Section 8.1.3). \2\ at each traverse
point during the
stratification test is:
Within 5% of mean, use 1-
point sampling (at the
point closest to the
mean); or.
Not within 5% of mean, but
is within
10% of mean, use 3-point
sampling. Locate points
according to Section
8.1.3.2.2 of this method.
.................... .................... Alternatively, if the Hg Prior to 1/1/09, you
concentration at each may (1) forgo
point is: stratification
Within 0.2 [mu]g/m\3\ of sampling points (as
mean, use 1-point per Section
sampling (at the point 8.1.3.2.2) or (2)
closest to the mean); or. perform a SO2
Not within 0.2 [mu]g/m\3\ of (see Sections
mean, use 3-point 6.5.6.1 and 6.5.6.3
sampling. Locate points of appendix A to
according to Section part 75), in lieu
8.1.3.2.2 of this method. of a Hg
stratification
test. If the test
location is
unstratified or
minimally
stratified for SO2,
it can be
considered
unstratified or
minimally
stratified for Hg
also.
[[Page 51509]]
.................... .................... If the Hg concentration On and after 1/1/09,
is > 10% of the mean at only Hg
any point, then, if the stratification
alternative tests are
specification is not met acceptable for the
or if the stack diameter purposes of this
is < = 2.4 m (7.8 ft): method.
Perform sampling
at 12 Method 1 points;
or.
Sample at 3
points located at 16.7,
50.0 and 83.3% of the
measurement line that
exhibited the highest
average Hg concentration
during stratification
test; or.
Sample at 6
Method 1 points along
the line that exhibited
the highest average Hg
concentration (Part 75
RATAs, only).
M.................. Data Recording...... Frequency........... Once per cycle........... During run.
S.................. Data Parameters..... Sample concentration All analyzer readings Each run.
and calibration during each run within
span. calibration span.
M.................. Data Parameters..... Sample concentration All analyzer readings Each spike
and calibration during dynamic spiking injection.
span. tests within 120% of
calibration span.
M.................. Data Parameters..... Sample concentration Average Hg concentration Each run.
and calibration for the run < =
span. calibration span.
----------------------------------------------------------------------------------------------------------------
\1\ M = Mandatory; S = Suggested; A = Alternative.
\2\ These may either be the unadjusted Hg concentrations or concentrations normalized to account for temporal
variations.
10.0 Calibration and Standardization
What measurement system calibrations are required?
Your analyzer must be calibrated with Hg[deg] standards. The
initial 3-point system calibration error test described in Section
8.2.4 is required before you start the test. Also, prior to and
following test runs, the two-point system integrity checks described
in Sections 8.2.5 and 8.2.8 are required. On and after January 1,
2009, the pre-test dynamic spiking procedure described in section
8.2.7 is also required to verify that the accuracy of the
measurement system is suitable and not adversely affected by the
flue gas matrix.
11.0 Analytical Procedures
Because sample collection and analysis are performed together
(see Section 8), additional discussion of the analytical procedure
is not necessary.
12.0 Calculations and Data Analysis
You must follow the procedures for calculations and data
analysis listed in this section.
12.1 Nomenclature. The terms used in the equations are defined
as follows:
Bws = Moisture content of sample gas as measured by
Method 4 in Appendix A-3 to this part, percent/100.
Cavg = Average unadjusted Hg concentration for the test
run, as indicated by the data recorder [mu]g/m\3\.
Cbaseline = Average Hg concentration measured before and
after dynamic spiking injections, [mu]g/m\3\.
Cd = Hg concentration, dry basis, [mu]g/m\3\.
Cdif = Absolute value of the difference between the
measured Hg concentrations of the reference HgCl2
calibration gas, with and without the individual or combined
interference gases, [mu]g/m\3\.
Cdif avg = Average of the 3 absolute values of the
difference between the measured Hg concentrations of the reference
HgCl2 calibration gas, with and without the individual or
combined interference gases, [mu]g/m\3\.
Cgas = Average Hg concentration in the effluent gas for
the test run, adjusted for system calibration error, [mu]g/m\3\.
Cint = Measured Hg concentration of the reference
HgCl2 calibration gas plus the individual or combined
interference gases, [mu]g/m\3\.
Cm = Average of pre- and post-run system integrity check
responses for the upscale (i.e., mid- or high-level) calibration
gas, [mu]g/m\3\.
Cma = Actual concentration of the upscale (i.e., mid- or
high-level) calibration gas used for the system integrity checks,
[mu]g/m\3\.
C0 = Average of pre- and post-run system integrity check
responses from the zero gas, [mu]g/m\3\.
Cnative = Vapor phase Hg concentration in the source
effluent, [mu]g/m\3\.
Cref = Measured Hg concentration of the reference
HgCl2 calibration gas alone, in the interference test,
[mu]g/m\3\.
Cs = Measured concentration of a calibration gas (zero-,
low-, mid-, or high-level), when introduced in system calibration
mode, [mu]g/m\3\.
Cspike = Actual Hg concentration of the spike gas, [mu]g/
m\3\.
C*spike = Hg concentration of the spike gas required to
achieve a certain target value for the spiked sample Hg
concentration, [mu]g/m\3\.
Css = Measured Hg concentration of the spiked sample at
the target level, [mu]g/m\3\.
C*ss = Expected Hg concentration of the spiked sample at
the target level, [mu]g/m\3\.
Ctarget = Target Hg concentration of the spiked sample,
[mu]g/m\3\.
CTnative = Measured tracer gas concentration present in
native effluent gas, ppm.
CTdir = Tracer gas concentration injected with spike gas,
ppm.
CTv = Diluted tracer gas concentration measured in a
spiked sample, ppm.
Cv = Certified Hg[deg] or HgCl2 concentration
of a calibration gas (zero, low, mid, or high), [mu]g/m\3\.
Cw = Hg concentration measured under moist sample
conditions, wet basis, [mu]g/m\3\.
CS = Calibration span, [mu]g/m\3\.
D = Zero or upscale drift, percent of calibration span.
DF = Dilution factor of the spike gas, dimensionless.
I = Interference response, percent of calibration span.
Qprobe = Total flow rate of the stack gas sample plus the
spike gas, liters/min.
Qspike = Flow rate of the spike gas, liters/min.
Ri = Individual injection spike recovery, %;.
R= Mean value of spike recoveries at a particular target level, %;.
RSD = Relative standard deviation, %;.
SCE = System calibration error, percent of calibration span.
SCEi = Pre-run system calibration error during the two-
point system integrity check, percent of calibration span.
SCEf = Post-run system calibration error during the two-
point system integrity check, percent of calibration span.
12.2 System Calibration Error. Use Equation 30A-1 to calculate
the system calibration error. Equation 30A-1 applies to: 3-point
system calibration error tests performed with Hg[deg] standards; and
pre- and post-run two-point system integrity checks performed with
HgCl2.
[GRAPHIC] [TIFF OMITTED] TR07SE07.005
12.3 Drift Assessment. Use Equation 30A-2 to separately
calculate the zero and upscale drift for each test run.
[GRAPHIC] [TIFF OMITTED] TR07SE07.006
12.3 Effluent Hg Concentration. For each test run, calculate
Cavg, the arithmetic average of all valid Hg
concentration values recorded during the run. Then, adjust the value
of Cavg
[[Page 51510]]
for system calibration error, using Equation 30A-3.
[GRAPHIC] [TIFF OMITTED] TR07SE07.007
12.4 Moisture Correction. Use Equation 30A-4a if your
measurements need to be corrected to a dry basis.
[GRAPHIC] [TIFF OMITTED] TR07SE07.008
Use Equation 30A-4b if your measurements need to be corrected to
a wet basis.
[GRAPHIC] [TIFF OMITTED] TR07SE07.009
12.5 Dynamic Spike Gas Concentrations. Use Equation 30A-5 to
determine the spike gas concentration needed to produce a spiked
sample with a certain ``target'' Hg concentration.
[GRAPHIC] [TIFF OMITTED] TR07SE07.010
12.6 Spiked Sample Concentration. Use Equation 30A-6 to
determine the expected or theoretical Hg concentration of a spiked
sample.
[GRAPHIC] [TIFF OMITTED] TR07SE07.011
12.7 Spike Recovery. Use Equation 30A-7 to calculate the
percentage recovery of each spike.
[GRAPHIC] [TIFF OMITTED] TR07SE07.012
12.8 Relative Standard Deviation. Use Equation 30A-8 to
calculate the relative standard deviation of the individual
percentage spike recovery values from the mean.
[GRAPHIC] [TIFF OMITTED] TR07SE07.013
12.9 Spike Dilution Factor. Use Equation 30A-9 to calculate the
spike dilution factor, using either direct flow measurements or
tracer gas measurements.
[GRAPHIC] [TIFF OMITTED] TR07SE07.014
12.10 Native Concentration. For spiking procedures that inject
blank or carrier gases (at the spiking flow rate, Qspike)
between spikes, use Equation 30A-10 to calculate the native
concentration.
[GRAPHIC] [TIFF OMITTED] TR07SE07.015
For spiking procedures that halt all injections between spikes,
the native concentration equals the average baseline concentration
(see Equation 30A-11).
[GRAPHIC] [TIFF OMITTED] TR07SE07.016
12.11 Overall Interference Response. Use equation 30A-12 to
calculate the overall interference response.
[GRAPHIC] [TIFF OMITTED] TR07SE07.017
Where, for each interference gas (or mixture):
[GRAPHIC] [TIFF OMITTED] TR07SE07.018
[GRAPHIC] [TIFF OMITTED] TR07SE07.019
[[Page 51511]]
13.0 Method Performance
13.1 System Calibration Error Test. This specification applies
to the 3-point system calibration error tests using Hg0.
At each calibration gas level tested (low-, mid-, or high-level),
the calibration error must be within 5.0 percent of the
calibration span. Alternatively, the results are acceptable if
[bond] Cs - Cv [bond] <=0.5 [mu]g/
m3.
13.2 System Integrity Checks. This specification applies to all
pre- and post-run 2-point system integrity checks using
HgCl2 and zero gas. At each calibration gas level tested
(zero and mid- or high-level), the error must be within < plus-
minus>5.0 percent of the calibration span. Alternatively, the
results are acceptable if [bond] Cs - Cv
[bond] <=0.5 [mu]g/m3.
13.3 Drift. For each run, the low-level and upscale drift must
be less than or equal to 3.0 percent of the calibration span. The
drift is also acceptable if the pre- and post-run system integrity
check responses do not differ by more than 0.3 [mu]g/m3
(i.e., [bond] Cs post-run - Cs pre-run [bond]
<=0.3 [mu]g/m3).
13.4 Interference Test. Summarize the results following the
format contained in Table 30A-4. For each interference gas (or
mixture), calculate the mean difference between the measurement
system responses with and without the interference test gas(es). The
overall interference response for the analyzer that was used for the
test (calculated according to Equation 30A-12), must not be greater
than 3.0 percent of the calibration span used for the test (see
Section 8.6). The results of the interference test are also
acceptable if the sum of the absolute average differences for all
interference gases (i.e., [Sigma] Cdif avg) does not
exceed 0.3 [mu]g/m3.
13.5 Dynamic Spiking Test. For the pre-test dynamic spiking, the
mean value of the percentage spike recovery must be 100 < plus-
minus>10 percent. In addition, the relative standard deviation (RSD)
of the individual percentage spike recovery values from the mean
must be < =5.0 percent. Alternatively, if the mean percentage
recovery is not met, the results are acceptable if the absolute
difference between the theoretical spiked sample concentration (see
Section 12.6) and the actual average value of the spiked sample
concentration is <=0.5 [mu]g/m3.
14.0 Pollution Prevention [Reserved]
15.0 Waste Management [Reserved]
16.0 References
1. EPA Traceability Protocol for Qualification and Certification
of Elemental Mercury Gas Generators, expected publication date
December 2008, see http://www.epa.gov/ttn/emc.
2. EPA Traceability Protocol for Qualification and Certification
of Oxidized Mercury Gas Generators, expected publication date
December 2008, see http://www.epa.gov/ttn/emc.
3. EPA Traceability Protocol for Assay and Certification of
Gaseous Calibration Standards, expected revision publication date
December 2008, see http://www.epa.gov/ttn/emc.
17.0 Figures and Tables
BILLING CODE 6560-50-C
[[Page 51512]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.020
[[Page 51513]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.021
[[Page 51514]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.022
[[Page 51515]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.023
Table 30A-3.--Interference Check Gas Concentrations
------------------------------------------------------------------------
Concentration, tentative--(balance
Potential interferent gas \1\ N2)
------------------------------------------------------------------------
CO2............................... 15% 1% CO2
CO................................ 100 20 ppm
HCl \2\........................... 100 20 ppm
NO \2\............................ 250 50 ppm
SO2............................... 200 20 ppm
O2................................ 3% 1% O2
H2O............................... 10% 1% H2O
Nitrogen.......................... Balance
Other ............................
------------------------------------------------------------------------
\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.
\2\ HCl and NO must be tested as a mixture.
[[Page 51516]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.024
[[Page 51517]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.025
[[Page 51518]]
Method 30B--Determination of Total Vapor Phase Mercury Emissions From
Coal-Fired Combustion Sources Using Carbon Sorbent Traps
1.0 Scope and Application
What is Method 30B?
Method 30B is a procedure for measuring total vapor phase
mercury (Hg) emissions from coal-fired combustion sources using
sorbent trap sampling and an extractive or thermal analytical
technique. This method is only intended for use only under
relatively low particulate conditions (e.g., sampling after all
pollution control devices). Quality assurance and quality control
requirements are included to assure that you, the tester, collect
data of known and acceptable quality for each testing program. This
method does not completely describe all equipment, supplies, and
sampling and analytical procedures you will need, but instead refers
to other test methods for some of the details. Therefore, to obtain
reliable results, you should also have a thorough knowledge of these
additional methods which are found in Appendices A-1 and A-3 to this
part:
(a) Method 1--Sample and Velocity Traverses for Stationary
Sources.
(b) Method 4--Determination of Moisture Content in Stack Gases.
(c) Method 5--Determination of Particulate Matter Emissions from
Stationary Sources
1.1 Analytes. What does this method determine? This method is
designed to measure the mass concentration of total vapor phase Hg
in flue gas, including elemental Hg (Hg\0\) and oxidized forms of Hg
(Hg+\2\), in micrograms per dry standard cubic meter
([mu]g/dscm).
------------------------------------------------------------------------
Analytical range and
Analyte CAS No. sensitivity
------------------------------------------------------------------------
Elemental Hg (Hg \0\ )............. 7439-97-6 Typically 0.1 [mu]g/
dscm to >50 [mu]g/
dscm.
Oxidized Hg (Hg+\2\)............... ........... (Same)
------------------------------------------------------------------------
1.2 Applicability. When is this method required? Method 30B is a
reference method for relative accuracy test audits (RATAs) of vapor
phase Hg CEMS and sorbent trap monitoring systems installed at coal-
fired boilers and is also appropriate for Hg emissions testing at
such boilers. It is intended for use only under relatively low
particulate conditions (i.e., sampling after all pollution control
devices); in cases where significant amounts of particle-bound Hg
may be present, an isokinetic sampling method for Hg should be used.
Method 30B may also be specified by New Source Performance Standards
(NSPS), National Emission Standards for Hazardous Air Pollutants
(NESHAP), emissions trading programs, State Implementation Plans
(SIPs), and operating permits that require measurement of Hg
concentrations in stationary source emissions, either to determine
compliance with an applicable emission standard or limit, or to
conduct RATAs of Hg CEMS and sorbent trap monitoring systems.
1.3 Data Quality Objectives (DQO). How good must my collected
data be? Method 30B has been designed to provide data of high and
known quality for Hg emissions testing and for RATA testing of Hg
monitoring systems, including CEMS and sorbent trap monitors. In
these and other applications, the principal objective is to ensure
the accuracy of the data at the actual emissions levels and in the
actual emissions matrix encountered. To meet this objective, NIST-
traceable calibration standards must be used and method performance
tests are required.
2.0 Summary of Method
Known volumes of flue gas are extracted from a stack or duct
through paired, in-stack sorbent media traps at an appropriate flow
rate. Collection of mercury on the sorbent media in the stack
mitigates potential loss of mercury during transport through a
probe/sample line. For each test run, paired train sampling is
required to determine measurement precision and verify acceptability
of the measured emissions data. A field recovery test which assesses
recovery of an elemental Hg spike to determine measurement bias is
also used to verify data acceptability. The sorbent traps are
recovered from the sampling system, prepared for analysis as needed,
and analyzed by any suitable determinative technique that can meet
the performance criteria.
3.0 Definitions
3.1 Analytical System is the combined equipment and apparatus
used to perform sample analyses. This includes any associated sample
preparation apparatus e.g., digestion equipment, spiking systems,
reduction devices, etc., as well as analytical instrumentation such
as UV AA and UV AF cold vapor analyzers.
3.2 Calibration Standards are the Hg containing solutions
prepared from NIST traceable standards and are used to directly
calibrate analytical systems.
3.3 Independent Calibration Standard is a NIST traceable
standard obtained from a source or supplier independent of that for
the calibration standards and is used to confirm the integrity of
the calibration standards used.
3.4 Method Detection Limit (MDL) is the lowest mass of Hg
greater than zero that can be estimated and reported by your
candidate analytical technique. The MDL is statistically derived
from replicate low level measurements near your analytical
instrument's detection level.
3.5 NIST means the National Institute of Standards and
Technology, located in Gaithersburg, Maryland.
3.6 Run means a series of gas samples taken successively from
the stack or duct. A test normally consists of a specific number of
runs.
3.7 Sorbent Trap means a cartridge or sleeve containing a
sorbent media (typically activated carbon treated with iodine or
some other halogen) with multiple sections separated by an inert
material such as glass wool. These sorbent traps are optimized for
the quantitative capture of elemental and oxidized forms of Hg and
can be analyzed by multiple techniques.
3.8 Test refers to the series of runs required by the applicable
regulation.
3.9 Thermal Analysis means an analytical technique where the
contents of the sorbent traps are analyzed using a thermal technique
(desorption or combustion) to release the captured Hg in a
detectable form for quantification.
3.10 Wet Analysis means an analytical technique where the
contents of the sorbent tube are first leached or digested to
quantitatively transfer the captured Hg to liquid solution for
subsequent analysis.
4.0 Interferences
Interferences may result from the sorbent trap material used as
well as from the measurement environment itself. The iodine present
on some sorbent traps may impart a negative measurement bias. High
levels of sulfur trioxide (SO3) are also suspected to
compromise the performance of sorbent trap Hg capture. These, and
other, potential interferences are assessed by performing the
analytical matrix interference, Hg\0\ and HgCl2
analytical bias and field recovery tests.
5.0 Safety
What safety measures should I consider when using this method?
This method may require you to work with hazardous materials and in
hazardous conditions. You are encouraged to establish safety
procedures before using the method. Among other precautions, you
should become familiar with the safety recommendations in the gas
analyzer user's manual. Occupational Safety and Health
Administration (OSHA) regulations concerning use of compressed gas
cylinders and noxious gases may apply.
5.1 Site Hazards. Prior to applying these procedures/
specifications in the field, the potential hazards at the test site
should be considered; advance coordination with the site is critical
to understand the conditions and applicable safety policies. At a
minimum, portions of the sampling system will be hot, requiring
appropriate gloves, long sleeves, and caution in handling this
equipment.
5.2 Laboratory Safety. Policies should be in place to minimize
risk of chemical exposure and to properly handle waste disposal in
the laboratory. Personnel shall wear appropriate laboratory attire
according to a Chemical Hygiene Plan established by the laboratory.
5.3 Reagent Toxicity/Carcinogenicity. The toxicity and
carcinogenicity of any reagents used must be considered. Depending
upon the sampling and analytical technologies selected, this
measurement may involve hazardous materials, operations, and
equipment and this method does not address all of the safety
problems associated with implementing this approach. It is the
responsibility of the user to establish appropriate safety and
health practices and determine the applicable regulatory limitations
prior to performance. Any chemical should be regarded as a potential
health hazard and exposure to these compounds should be minimized.
Chemists should refer to the Material Safety Data Sheet (MSDS) for
each chemical used.
5.4 Waste Disposal. Any waste generated by this procedure must
be disposed of
[[Page 51519]]
according to a hazardous materials management plan that details and
tracks various waste streams and disposal procedures.
6.0 Equipment and Supplies
The following list is presented as an example of key equipment
and supplies likely required to measure vapor-phase Hg using a
sorbent trap sampling system. It is recognized that additional
equipment and supplies may be needed. Collection of paired samples
is required.
6.1 Sorbent Trap Sampling System. A typical sorbent trap
sampling system is shown in Figure 30B-1 in Section 17.0. The
sorbent trap sampling system shall include the following components:
6.1.1 Sorbent Traps. The sorbent media used to collect Hg must
be configured in a trap with at least two distinct segments or
sections, connected in series, that are amenable to separate
analyses. Section 1 is designated for primary capture of gaseous Hg.
Section 2 is designated as a backup section for determination of
vapor phase Hg breakthrough. Each sorbent trap must be inscribed or
otherwise permanently marked with a unique identification number,
for tracking purposes. The sorbent media may be any collection
material (e.g., carbon, chemically-treated filter, etc.) capable of
quantitatively capturing and recovering for subsequent analysis, all
gaseous forms of Hg in the emissions from the intended application.
Selection of the sorbent media shall be based on the material's
ability to achieve the performance criteria contained in this method
as well as the sorbent's vapor phase Hg capture efficiency for the
emissions matrix and the expected sampling duration at the test
site. The sorbent media must be obtained from a source that can
demonstrate their quality assurance and quality control (see Section
7.2). The paired sorbent traps are supported on a probe (or probes)
and inserted directly into the flue gas stream.
6.1.2 Sampling Probe Assembly. Each probe assembly shall have a
leak-free attachment to the sorbent trap(s). Each sorbent trap must
be mounted at the entrance of or within the probe such that the gas
sampled enters the trap directly. Each probe/sorbent trap assembly
must be heated to a temperature sufficient to prevent liquid
condensation in the sorbent trap(s). Auxiliary heating is required
only where the stack temperature is too low to prevent condensation.
Use a calibrated thermocouple to monitor the stack temperature. A
single probe capable of operating the paired sorbent traps may be
used. Alternatively, individual probe/sorbent trap assemblies may be
used, provided that the individual sorbent traps are co-located to
ensure representative Hg monitoring.
6.1.3 Moisture Removal Device. A moisture removal device or
system shall be used to remove water vapor from the gas stream prior
to entering dry gas flow metering devices.
6.1.4 Vacuum Pump. Use a leak-tight, vacuum pump capable of
operating within the system's flow range.
6.1.5 Gas Flow Meter. A gas flow meter (such as a dry gas meter,
thermal mass flow meter, or other suitable measurement device) shall
be used to determine the total sample volume on a dry basis, in
units of standard cubic meters. The meter must be sufficiently
accurate to measure the total sample volume to within 2 percent and
must be calibrated at selected flow rates across the range of sample
flow rates at which the sampling train will be operated. The gas
flow meter shall be equipped with any necessary auxiliary
measurement devices (e.g., temperature sensors, pressure measurement
devices) needed to correct the sample volume to standard conditions.
6.1.6 Sample Flow Rate Meter and Controller. Use a flow rate
indicator and controller for maintaining necessary sampling flow
rates.
6.1.7 Temperature Sensor. Same as Section 6.1.1.7 of Method 5 in
Appendix A-3 to this part.
6.1.8 Barometer. Same as Section 6.1.2 of Method 5 in Appendix
A-3 to this part.
6.1.9 Data Logger (optional). Device for recording associated
and necessary ancillary information (e.g., temperatures, pressures,
flow, time, etc.).
6.2 Gaseous Hg\0\ Sorbent Trap Spiking System. A known mass of
gaseous Hg\0\ must be either present on or spiked onto the first
section of sorbent traps in order to perform the Hg\0\ and
HgCl2 analytical bias test and the field recovery study.
Any approach capable of quantitatively delivering known masses of
Hg\0\ onto sorbent traps is acceptable. Several spiking technologies
or devices are available to meet this objective. Their practicality
is a function of Hg mass spike levels. For low levels, NIST-
certified or NIST-traceable gas generators or tanks may be suitable.
An alternative system, capable of delivering almost any mass
required, makes use of NIST-certified or NIST-traceable Hg salt
solutions (e.g., HgCl2, Hg(NO3)2).
With this system, an aliquot of known volume and concentration is
added to a reaction vessel containing a reducing agent (e.g.,
stannous chloride); the Hg salt solution is reduced to Hg\0\ and
purged onto the sorbent trap using an impinger sparging system. When
available, information on example spiking systems will be posted at
http://www.epa.gov/ttn/emc.
6.3 Sample Analysis Equipment. Any analytical system capable of
quantitatively recovering and quantifying total Hg from the sorbent
media selected is acceptable provided that the analysis can meet the
performance criteria described in this method. Example recovery
techniques include acid leaching, digestion, and thermal desorption/
direct combustion. Example analytical techniques include, but are
not limited to, ultraviolet atomic fluorescence (UV AF), ultraviolet
atomic absorption (UV AA) with and without gold trapping, and X-ray
fluorescence (XRF) analysis.
6.3 Moisture Measurement System. If correction of the measured
Hg emissions for moisture is required (see Section 8.3.3.7), either
Method 4 in Appendix A-3 to this part or other moisture measurement
methods approved by the Administrator will be needed to measure
stack gas moisture content.
7.0 Reagents and Standards
7.1 Reagents and Standards. Only NIST-certified or NIST-
traceable calibration standards, standard reference materials, and
reagents shall be used for the tests and procedures required by this
method.
7.2 Sorbent Trap Media. The sorbent trap media shall be prepared
such that the material used for testing is of known and acceptable
quality. Sorbent supplier quality assurance/quality control measures
to ensure appropriate and consistent performance such as sorptive
capacity, uniformity of preparation treatments, and background
levels shall be considered.
8.0 Sample Collection and Handling
This section presents the sample collection and handling
procedures along with the pretest and on-site performance tests
required by this method. Since you may choose different options to
comply with certain performance criteria, each test report must
identify the specific options selected and document the results with
respect to the performance criteria of this method.
8.1 Sample Point Selection. What sampling site and sampling
points do I select? Same as Section 8.1 of Method 30A of this
appendix.
8.2 Measurement System Performance Tests. What performance
criteria must my measurement system meet? The following laboratory
and field procedures and associated criteria of this section are
designed to ensure (1) selection of a sorbent and analytical
technique combination capable of quantitative collection and
analysis of gaseous Hg, (2) collection of an adequate amount of Hg
on each sorbent trap during field tests, and (3) adequate
performance of the method for each test program: The primary
objectives of these performance tests are to characterize and verify
the performance of your intended analytical system and associated
sampling and analytical procedures, and to define the minimum amount
of Hg (as the sample collection target) that can be quantified
reliably.
(a) Analytical Matrix Interference Test;
(b) Determination of Minimum Sample Mass;
(c) Hg\0\ and HgCl2 Analytical Bias Test;
(d) Determination of Nominal Sample Volume;
(e) Field Recovery Test.
8.2.1 Analytical Matrix Interference Test and Minimum Sample
Dilution.
(a) The analytical matrix interference test is a laboratory
procedure. It is required only if you elect to use a liquid
digestion analytical approach and needs to be performed only once
for each sorbent material used. The purpose of the test is to verify
the presence or absence of known and potential analytical matrix
interferences, including the potential negative bias associated with
iodine common to many sorbent trap materials. The analytical matrix
interference test determines the minimum dilution (if any) necessary
to mitigate matrix effects on the sample digestate solutions.
(b) The result of the analytical matrix interference test, i.e.,
the minimum sample dilution required (if any) for all sample
[[Page 51520]]
analyses, is used to establish the minimum sample mass needed for
the Hg\0\ and HgCl2 analytical bias test and to determine
the nominal sample volume for a test run. The analytical matrix
interference test is sorbent material-specific and shall be
performed for each sorbent material you intend to use for field
sampling and analysis. The test shall be performed using a mass of
sorbent material comparable to the sorbent mass typically used in
the first section of the trap for sampling. Similar sorbent
materials from different sources of supply are considered to be
different materials and must be tested individually. You must
conduct the analytical matrix interference test for each sorbent
material prior to the analysis of field samples.
8.2.1.1 Analytical Matrix Interference Test Procedures. Digest
and prepare for analysis a representative mass of sorbent material
(unsampled) according to your intended laboratory techniques for
field samples. Analyze the digestate according to your intended
analytical conditions at the least diluted level you intend to use
for sample analysis (e.g., undiluted, 1 in 10 dilution, etc.).
Determine the Hg concentration of the undiluted digestate solution.
Prepare a series of solutions with a fixed final volume containing
graduated aliquots of the sample digestate and, a fixed aliquot of a
calibration standard (with the balance being Hg-free reagent or
H20) to establish solutions of varied digestate dilution
ratio (e.g., 1:2, 1:5, 1:10, 1:100, etc.--see example in Section
8.2.1.3, below). One of these solutions should contain only the
aliquot of the calibration standard in Hg-free reagent or
H2O. This will result in a series of solutions where the
amount of Hg is held relatively constant and only the volume of
digestate diluted is varied. Analyze each of these solutions
following intended sample analytical procedures and conditions,
determining the concentration for each solution.
8.2.1.2 Analytical Matrix Interference Test Acceptance Criteria.
Compare the measured concentration of each solution containing
digestate to the measured concentration of the digestate-free
solution. The lowest dilution ratio of any solution having a Hg
concentration within 5 percent of the digestate-free
solution is the minimum dilution ratio required for analysis of all
samples. If you desire to measure the digestate without dilution,
the 5 percent criterion must be met at a dilution ratio
of at least 9:10 (i.e., >=90% digestate).
8.2.1.3 Example Analytical Matrix Interference Test. An example
analytical matrix interference test is presented below. Additional
information on the conduct of the analytical matrix interference
test will be posted at http://www.epa.gov/ttn/emc. Determine the
most sensitive working range for the analyzer to be used. This will
be a narrow range of concentrations. Digest and prepare for analysis
a representative mass of sorbent material (unsampled) according to
your intended laboratory techniques for sample preparation and
analysis. Prepare a calibration curve for the most sensitive
analytical region, e.g., 0.0, 0.5, 1.0, 3.0, 5.0, 10 ppb. Using the
highest calibration standard, e.g., 10.0 ppb, prepare a series of
solutions by adding successively smaller increments of the digestate
to a fixed volume of the calibration standard and bringing each
solution to a final fixed volume with mercury-free deionized water
(diH2O). To 2.0 ml of the calibration standard add 18.0,
10.0, 4.0, 2.0, 1.0, 0.2, and 0.0 ml of the digestate. Bring the
final volume of each solution to a total volume of 20 ml by adding
0.0, 8.0, 14.0, 16.0, 17.0, 17.8, and 18.0 ml of diH2O.
This will yield solutions with dilution ratios of 9:10, 1:2, 1:5,
1:10, 1:20, 1:100, and 0:10, respectively. Determine the Hg
concentration of each solution. The dilution ratio of any solution
having a concentration that is within 5 percent of the
concentration of the solution containing 0.0 ml of digestate is an
acceptable dilution ratio for analyzing field samples. If more than
one solution meets this criterion, the one with the lowest dilution
ratio is the minimum dilution required for analysis of field
samples. If the 9:10 dilution meets this criterion, then no sample
dilution is required.
8.2.2 Determination of Minimum Sample Mass. The minimum mass of
Hg that must be collected per sample must be determined. This
information is necessary in order to effectively perform the Hg\0\
and HgCl2 Analytical Bias Test, to estimate target sample
volumes/sample times for test runs, and to ensure the quality of the
measurements. The determination of minimum sample mass is a direct
function of analytical technique, measurement sensitivity,
dilutions, etc. This determination is required for all analytical
techniques. Based on the analytical approach you employ, you should
determine the most sensitive calibration range. Based on a
calibration point within that range, you must consider all sample
treatments (e.g., dilutions) to determine the mass of sample that
needs to be collected to ensure that all sample analyses fall within
your calibration curve.
8.2.2.1 Determination of Minimum Calibration Concentration or
Mass. Based on your instrument's sensitivity and linearity,
determine the calibration concentrations or masses that make up a
representative low level calibration range. Verify that you are able
to meet the multipoint calibration performance criteria in section
11.0 of this method. Select a calibration concentration or mass that
is no less than 2 times the lowest concentration or mass in your
calibration curve. The lowest point in your calibration curve must
be at least 5, and preferably 10, times the Method Detection Limit
(MDL), which is the minimum amount of the analyte that can be
detected and reported. The MDL must be determined at least once for
the analytical system using an MDL study such as that found in
section 17.0 of the proposed amendments to EPA Method 301 (69 FR
76642, 12/22/2004).
Note to Section 8.2.2.1: While it might be desirable to base the
minimum calibration concentration or mass on the lowest point in the
calibration curve, selecting a higher concentration or mass is
necessary to ensure that all analyses of the field samples will fall
within the calibration curve. Therefore, it is strongly recommended
that you select a minimum calibration concentration or mass that is
sufficiently above the lowest point of the calibration curve (see
examples in sections 8.2.2.2.1 and 8.2.2.2.2 below).
8.2.2.2 Determination of Minimum Sample Mass. Based on your
minimum calibration concentration or mass and other sample
treatments including, but not limited to, final digestate volume and
minimum sample dilution, determine the minimum sample mass.
Consideration should also be given to the Hg levels expected to be
measured in Section 2 of the sorbent traps and to the breakthrough
criteria presented in Table 9-1.
8.2.2.2.1 Example Determination of Minimum Sample Mass for
Thermal Desorption Analysis. A thermal analysis system has been
calibrated at five Hg mass levels: 10 ng, 20 ng, 50 ng, 100 ng, 200
ng, and shown to meet the calibration performance criteria in this
method. Based on 2 times the lowest point in the calibration curve,
20 ng is selected as the minimum calibration mass. Because the
entire sample is analyzed and there are no dilutions involved, the
minimum sample mass is also 20 ng.
Note: In this example, if the typical background (blank) Hg
levels in section 2 were relatively high (e.g., 3 to 5 ng), a sample
mass of 20 ng might not have been sufficient to ensure that the
breakthrough criteria in Table 9-1 would be met, thereby
necessitating the use of a higher point on the calibration curve
(e.g., 50 ng) as the minimum calibration and sample mass.
8.2.2.2.2 Example Determination of Minimum Sample Mass for Acid
Leachate/Digestate Analysis. A cold vapor analysis system has been
calibrated at four Hg concentration levels: 2 ng/L, 5 ng, 10 ng/L,
20 ng/L, and shown to meet the calibration performance criteria in
this method. Based on 2 times the lowest point in the calibration
curve, 4 ng/L was selected as the minimum calibration concentration.
The final sample volume of a digestate is nominally 50 ml (0.05 L)
and the minimum dilution necessary was determined to be 1:100 by the
Analytical Matrix Interference Test of Section 8.2.1. The following
calculation would be used to determine the minimum sample mass.
Minimum sample mass = (4 ng/L) x (0.05 L) x (100) = 20 ng
Note: In this example, if the typical background (blank) Hg
levels in section 2 were relatively high (e.g., 3 to 5 ng), a sample
mass of 20 ng might not have been sufficient to ensure that the
breakthrough criterion in Table 9-1 would be met, thereby
necessitating the use of a higher point on the calibration curve
(e.g., 10 ng/L) as the minimum calibration concentration.
8.2.3 Hg\0\ and HgCl2 Analytical Bias Test. Before
analyzing any field samples, the laboratory must demonstrate the
ability to recover and accurately quantify Hg\0\ and
HgCl2 from the chosen sorbent media by performing the
following analytical bias test for sorbent traps spiked with Hg\0\
and HgCl2. The analytical bias test is performed at a
minimum of two distinct sorbent trap Hg loadings that will: (1)
Represent the lower and upper bound of sample Hg loadings for
application of the analytical technique to the
[[Page 51521]]
field samples, and (2) be used for data validation.
8.2.3.1 Hg\0\ and HgCl2 Analytical Bias Test
Procedures. Determine the lower and upper bound mass loadings. The
minimum sample mass established in Section 8.2.2.2 can be used for
the lower bound Hg mass loading although lower Hg loading levels are
acceptable. The upper bound Hg loading level should be an estimate
of the greatest mass loading that may result as a function of stack
concentration and volume sampled. As previously noted, this test
defines the bounds that actual field samples must be within in order
to be valid.
8.2.3.1.1 Hg\0\ Analytical Bias Test. Analyze the front section
of three sorbent traps containing Hg\0\ at the lower bound mass
loading level and the front section of three sorbent traps
containing Hg\0\ at the upper bound mass loading level. In other
words, analyze each mass loading level in triplicate. You may refer
to Section 6.2 for spiking guidance. Prepare and analyze each spiked
trap, using the same techniques that will be used to prepare and
analyze the field samples. The average recovery for the three traps
at each mass loading level must be between 90 and 110 percent. If
multiple types of sorbent media are to be analyzed, a separate
analytical bias test is required for each sorbent material.
8.2.3.1.2 HgCl2 Analytical Bias Test. Analyze the
front section of three sorbent traps containing HgCl2 at
the lower bound mass loading level and the front section of three
traps containing HgCl2 at the upper bound mass loading
level. HgCl2 can be spiked as a gas, or as a liquid
solution containing HgCl2. However the liquid volume
spiked must be < 100 [mu]L. Prepare and analyze each spiked trap,
using the techniques that will be used to prepare and analyze the
field samples. The average recovery for three traps at each spike
concentration must be between 90 and 110 percent. Again, if multiple
types of sorbent media are to be analyzed, a separate analytical
bias test is required for each sorbent material.
8.2.4 Determination of Target Sample Volume. The target sample
volume is an estimate of the sample volume needed to ensure that
valid emissions data are collected (i.e., that sample mass Hg
loadings fall within the analytical calibration curve and are within
the upper and lower bounds set by the analytical bias tests). The
target sample volume and minimum sample mass can also be determined
by performing a diagnostic test run prior to initiation of formal
testing.
Example: If the minimum sample mass is 50 ng and the
concentration of mercury in the stack gas is estimated to be 2
[mu]g/m\3\ (ng/L) then the following calculation would be used to
determine the target sample volume:
Target Sample Volume = (50 ng)/(2 ng/L) = 25 L
Note: For the purposes of relative accuracy testing of Hg
monitoring systems under part 75 of this chapter and Performance
Specification 12A in appendix B to this part, when the stack gas Hg
concentration is expected to be very low (< 0.5 [mu]g/dscm) you may
estimate the Hg concentration at 0.5 [mu]g/dscm.
8.2.5 Determination of Sample Run Time. Sample run time will be
a function of minimum sample mass (see Section 8.2.2), target sample
volume and nominal equipment sample flow rate. The minimum sample
run time for conducting relative accuracy test audits of Hg
monitoring systems is 30 minutes and for emissions testing to
characterize an emission source is 1 hour. The target sample run
time can be calculated using the following example.
Example: If the target sample volume has been determined to be
25 L, then the following formula would be used to determine the
sampling time necessary to acquire 25 L of gas when sampling at a
rate of 0.4 L/min.
Sampling time (min) = 25 L / 0.4 L/min = 63 minutes
8.2.6 Field Recovery Test. The field recovery test provides a
test program-specific verification of the performance of the
combined sampling and analytical approach. Three sets of paired
samples, one of each pair which is spiked with a known level of Hg,
are collected and analyzed and the average recovery of the spiked
samples is used to verify performance of the measurement system
under field conditions during that test program. The conduct of this
test requires an estimate or confirmation of the stack Hg
concentrations at the time of testing.
8.2.6.1 Calculation of Pre-sampling Spiking Level. Determine the
sorbent trap spiking level for the field recovery test using
estimates of the stack Hg concentration, the target sample flow
rate, and the planned sample duration. First, determine the Hg mass
expected to be collected in section 1 of the sorbent trap. The pre-
sampling spike must be within 50 to 150 percent of this expected
mass.
Example calculation: For an expected stack Hg concentration of 5
ug/m\3\ (ng/L) a target sample rate of 0.40 liters/min, and a sample
duration of 1 hour:
(0.40 L/min)*(60 min)*(5ng/L) = 120 ng
A Hg spike of 60 to 180 ng (50-150% of 120 ng) would be
appropriate.
8.2.6.2 Procedures. Set up two identical sampling trains. One of
the sampling trains shall be designated the spiked train and the
other the unspiked train. Spike Hg\0\ onto the front section of the
sorbent trap in the spiked train before sampling. The mass of Hg
spiked shall be 50 to 150 percent of the mass expected to be
collected with the unspiked train. Sample the stack gas with the two
trains simultaneously using the same procedures as for the field
samples (see Section 8.3). The total sample volume must be within
20 percent of the target sample volume for the field
sample test runs. Analyze the sorbent traps from the two trains
utilizing the same analytical procedures and instrumentation as for
the field samples (see Section 11.0). Determine the fraction of
spiked Hg recovered (R) using the equations in Section 12.7. Repeat
this procedure for a total of three runs. Report the individual R
values in the test report; the average of the three R values must be
between 85 and 115 percent.
Note to section 8.2.6.2: It is acceptable to perform the field
recovery test concurrent with actual test runs (e.g., through the
use of a quad probe). It is also acceptable to use the field
recovery test runs as test runs for emissions testing or for the
RATA of a Hg monitoring system under part 75 of this chapter and
Performance Specification 12A in appendix B to this part, if certain
conditions are met. To determine whether a particular field recovery
test run may be used as a RATA run, subtract the mass of the Hg\0\
spike from the total Hg mass collected in sections 1 and 2 of the
spiked trap. The difference represents the mass of Hg in the stack
gas sample. Divide this mass by the sample volume to obtain the Hg
concentration in the effluent gas stream, as measured with the
spiked trap. Compare this concentration to the corresponding Hg
concentration measured with the unspiked trap. If the paired trains
meet the relative deviation and other applicable data validation
criteria in Table 9-1, then the average of the two Hg concentrations
may be used as an emissions test run value or as the reference
method value for a RATA run.
8.3 Sampling. This section describes the procedures and criteria
for collecting the field samples for analysis. As noted in Section
8.2.6, the field recovery test samples are also collected using
these procedures.
8.3.1 Pre-test leak check. Perform a leak check of the sampling
system with the sorbent traps in place. For each of the paired
sampling trains, draw a vacuum in the train, and adjust the vacuum
to ~15 Hg; and, using the gas flow meter, determine leak
rate. The leak rate for an individual train must not exceed 4
percent of the target sampling rate. Once the leak check passes this
criterion, carefully release the vacuum in the sample train, then
seal the sorbent trap inlet until the probe is ready for insertion
into the stack or duct.
8.3.2 Determination of Flue Gas Characteristics. Determine or
measure the flue gas measurement environment characteristics (gas
temperature, static pressure, gas velocity, stack moisture, etc.) in
order to determine ancillary requirements such as probe heating
requirements (if any), initial sampling rate, moisture management,
etc.
8.3.3 Sample Collection
8.3.3.1 Remove the plug from the end of each sorbent trap and
store each plug in a clean sorbent trap storage container. Remove
the stack or duct port cap and insert the probe(s). Secure the
probe(s) and ensure that no leakage occurs between the duct and
environment.
8.3.3.2 Record initial data including the sorbent trap ID, date,
and the run start time.
8.3.3.3 Record the initial gas flow meter reading, stack
temperature, meter temperatures (if needed), and any other
appropriate information, before beginning sampling. Begin sampling
and target a sampling flow rate similar to that for the field
recovery test. Then, at regular intervals (< =5 minutes) during the
sampling period, record the date and time, the sample flow rate, the
gas meter reading, the stack temperature, the flow meter
temperatures (if using a dry gas meter), temperatures of heated
equipment such as the vacuum lines and the probes (if heated), and
the sampling system vacuum readings. Adjust the sampling flow rate
as necessary to maintain the initial sample flow
[[Page 51522]]
rate. Ensure that the total volume sampled for each run is within 20
percent of the total volume sampled for the field recovery test.
8.3.3.4 Data Recording. Obtain and record any essential
operating data for the facility during the test period, e.g., the
barometric pressure must be obtained for correcting sample volume to
standard conditions when using a dry gas meter. At the end of the
data collection period, record the final gas flow meter reading and
the final values of all other essential parameters.
8.3.3.5 Post-Test Leak Check. When sampling is completed, turn
off the sample pump, remove the probe(s) with sorbent traps from the
port, and carefully seal the end of each sorbent trap. Perform
another leak check of each sampling train with the sorbent trap in
place, at the maximum vacuum reached during the sampling period.
Record the leakage rates and vacuums. The leakage rate for each
train must not exceed 4 percent of the average sampling rate for the
data collection period. Following each leak check, carefully release
the vacuum in the sample train.
8.3.3.6 Sample Recovery. Recover each sampled sorbent trap by
removing it from the probe and sealing both ends. Wipe any deposited
material from the outside of the sorbent trap. Place the sorbent
trap into an appropriate sample storage container and store/preserve
in appropriate manner (see Section 8.3.3.8).
8.3.3.7 Stack Gas Moisture Determination. If the moisture basis
of the measurements made with this method (dry) is different from
the moisture basis of either: (1) the applicable emission limit; or
(2) a Hg CEMS being evaluated for relative accuracy, you must
determine the moisture content of the flue gas and correct for
moisture using Method 4 in appendix A-3 to this part. If correction
of the measured Hg concentrations for moisture is required, at least
one Method 4 moisture determination shall be made during each test
run.
8.3.3.8 Sample Handling, Preservation, Storage, and Transport.
While the performance criteria of this approach provide for
verification of appropriate sample handling, it is still important
that the user consider, determine, and plan for suitable sample
preservation, storage, transport, and holding times for these
measurements. Therefore, procedures in ASTM WK223 ``Guide for
Packaging and Shipping Environmental Samples for Laboratory
Analysis'' shall be followed for all samples, where appropriate. To
avoid Hg contamination of the samples, special attention should be
paid to cleanliness during transport, field handling, sampling,
recovery, and laboratory analysis, as well as during preparation of
the sorbent cartridges. Collection and analysis of blank samples
(e.g., reagent, sorbent, field, etc.,) is useful in verifying the
absence or source of contaminant Hg.
8.3.3.9 Sample Custody. Proper procedures and documentation for
sample chain of custody are critical to ensuring data integrity. The
chain of custody procedures in ASTM D4840-99 ``Standard Guide for
Sampling Chain-of-Custody Procedures'' shall be followed for all
samples (including field samples and blanks).
9.0 Quality Assurance and Quality Control
Table 9-1 summarizes the QA/QC performance criteria that are
used to validate the Hg emissions data from Method 30B sorbent trap
measurement systems.
Table 9-1.--Quality Assurance/Quality Control Criteria for Method 30B
----------------------------------------------------------------------------------------------------------------
QA/QC test or specification Acceptance criteria Frequency Consequences if not met
----------------------------------------------------------------------------------------------------------------
Gas flow meter calibration (At 3 Calibration factor (Yi) Prior to initial use Recalibrate at 3 points
settings or points). at each flow rate must and when post-test until the acceptance
be within check is not within criteria are met.
2% of the average 5% of Y.
value (Y).
Gas flow meter post-test calibration Calibration factor (Yi) After each field test. Recalibrate gas flow
check (Single-point). must be within < plus- For mass flow meters, meter at 3 points to
minus> 5% of the Y must be done on-site, determine a new value
value from the most using stack gas. of Y. For mass flow
recent 3-point meters, must be done
calibration. on-site, using stack
gas. Apply the new Y
value to the field
test data.
Temperature sensor calibration....... Absolute temperature Prior to initial use Recalibrate; sensor may
measures by sensor and before each test not be used until
within thereafter. specification is met.
1.5% of a reference
sensor.
Barometer calibration................ Absolute pressure Prior to initial use Recalibrate; instrument
measured by instrument and before each test may not be used until
within 10 thereafter. specification is met.
mm Hg of reading with
a mercury barometer.
Pre-test leak check.................. < = 4% of target Prior to sampling...... Sampling shall not
sampling rate. commence until the
leak check is passed.
Post-test leak check................. < = 4% of average After sampling......... Sample invalidated.*
sampling rate.
Analytical matrix interference test Establish minimum Prior to analyzing any Field sample results
(wet chemical analysis, only). dilution (if any) field samples; repeat not validated.
needed to eliminate for each type of
sorbent matrix sorbent used.
interferences.
Analytical bias test................. Average recovery Prior to analyzing Field samples shall not
between 90% and 110% field samples and be analyzed until the
for Hg\0\ and HgCl2 at prior to use of new percent recovery
each of the 2 spike sorbent media. criteria has been met.
concentration levels.
Multipoint analyzer calibration...... Each analyzer reading On the day of analysis, Recalibrate until
withini before analyzing any successful.
10% of true value and samples.
r\2\ >= 0.99.
Analysis of independent calibration Within 10% Following daily Recalibrate and repeat
standard. of true value. calibration, prior to independent standard
analyzing field analysis until
samples. successful.
Analysis of continuing calibration Within 10% Following daily Recalibrate and repeat
verification standard (CCVS). of true value. calibration, after independent standard
analyzing < =10 field analysis, reanalyze
samples, and at end of samples until
each set of analyses. successful, if
possible; for
destructive
techniques, samples
invalidated.
Test run total sample volume......... Within 20% Each individual sample. Sample invalidated.
of total volume
sampled during field
recovery test.
Sorbent trap section 2 breakthrough.. < 10% of section 1 Hg Every sample........... Sample invalidated.*
mass for Hg
concentrations > 1
[mu]g/dscm;.
[[Page 51523]]
< = 20% of section 1 Hg
mass for Hg
concentrations < = 1
[mu]g/dscm.
Paired sorbent trap agreement........ < = 10% Relative Every run.............. Run invalidated.*
Deviation (RD) mass
for Hg concentrations
> 1 [mu]g/dscm;
< = 20% RD or < = 0.2
[mu]g/dscm absolute
difference for Hg
concentrations < = 1
[mu]g/dscm.
Sample analysis...................... Within valid All Section 1 samples Reanalyze at more
calibration range where stack Hg concentrated level if
(within calibration concentation is >= 0.5 possible, samples
curve). [mu]g/dscm. invalidated if not
within calibrated
range.
Sample analysis...................... Within bounds of Hg\0\ All Section 1 samples Expand bounds of Hg\0\
and HgCl2 Analytical where stack Hg and HgCl2 Analytical
Bias Test. concentration is >= Bias Test; if not
0.5 [mu]g/dscm. successful, samples
invalidated.
Field recovery test.................. Average recovery Once per field test.... Field sample runs not
between 85% and 115% validated without
for Hg\0\. successful field
recovery test.
----------------------------------------------------------------------------------------------------------------
* And data from the pair of sorbent traps are also invalidated.
10.0 Calibration and Standardization
10.1 Only NIST-certified and NIST-traceable calibration
standards (i.e., calibration gases, solutions, etc.) shall be used
for the spiking and analytical procedures in this method.
10.2 Gas Flow Meter Calibration.
10.2.1 Preliminaries. The manufacturer or equipment supplier of
the gas flow meter should perform all necessary set-up, testing,
programming, etc., and should provide the end user with any
necessary instructions, to ensure that the meter will give an
accurate readout of dry gas volume in standard cubic meters for this
method.
10.2.2 Initial Calibration. Prior to its initial use, a
calibration of the gas flow meter shall be performed. The initial
calibration may be done by the manufacturer, by the equipment
supplier, or by the end user. If the flow meter is volumetric in
nature (e.g., a dry gas meter), the manufacturer or end user may
perform a direct volumetric calibration using any gas. For a mass
flow meter, the manufacturer, equipment supplier, or end user may
calibrate the meter using either: (1) A bottled gas mixture
containing 12 0.5% CO2, 7 0.5%
O2, and balance N2 (when this method is
applied to coal-fired boilers); (2) a bottled gas mixture containing
CO2, O2, and N2 in proportions
representative of the expected stack gas composition; or (3) the
actual stack gas.
10.2.2.1 Initial Calibration Procedures. Determine an average
calibration factor (Y) for the gas flow meter by calibrating it at
three sample flow rate settings covering the range of sample flow
rates at which the sampling system will be operated. You may either
follow the procedures in section 10.3.1 of Method 5 in appendix A-3
to this part or in section 16 of Method 5 in appendix A-3 to this
part. If a dry gas meter is being calibrated, use at least five
revolutions of the meter at each flow rate.
10.2.2.2 Alternative Initial Calibration Procedures.
Alternatively, you may perform the initial calibration of the gas
flow meter using a reference gas flow meter (RGFM). The RGFM may be:
(1) A wet test meter calibrated according to section 10.3.1 of
Method 5 in appendix A-3 to this part; (2) a gas flow metering
device calibrated at multiple flow rates using the procedures in
section 16 of Method 5 in appendix A-3 to this part; or (3) a NIST-
traceable calibration device capable of measuring volumetric flow to
an accuracy of 1 percent. To calibrate the gas flow meter using the
RGFM, proceed as follows: While the Method 30B sampling system is
sampling the actual stack gas or a compressed gas mixture that
simulates the stack gas composition (as applicable), connect the
RGFM to the discharge of the system. Care should be taken to
minimize the dead volume between the gas flow meter being tested and
the RGFM. Concurrently measure dry stack gas volume with the RGFM
and the flow meter being calibrated for at least 10 minutes at each
of three flow rates covering the typical range of operation of the
sampling system. For each set of concurrent measurements, record the
total sample volume, in units of dry standard cubic meters (dscm),
measured by the RGFM and the gas flow meter being tested.
10.2.2.3 Initial Calibration Factor. Calculate an individual
calibration factor Yi at each tested flow rate from
section 10.2.2.1 or 10.2.2.2 of this method (as applicable) by
taking the ratio of the reference sample volume to the sample volume
recorded by the gas flow meter. Average the three Yi
values, to determine Y, the calibration factor for the flow meter.
Each of the three individual values of Yi must be within
0.02 of Y. Except as otherwise provided in sections
10.2.2.4 and 10.2.2.5 of this method, use the average Y value from
the initial 3-point calibration to adjust subsequent gas volume
measurements made with the gas flow meter.
10.2.2.4 Pretest On-Site Calibration Check (Optional). For a
mass flow meter, if the most recent 3-point calibration of the flow
meter was performed using a compressed gas mixture, you may want to
conduct the following on-site calibration check prior to testing, to
ensure that the flow meter will accurately measure the volume of the
stack gas: While sampling stack gas, check the calibration of the
flow meter at one intermediate flow rate setting representative of
normal operation of the sampling system. If the pretest calibration
check shows that the value of Yi, the calibration factor
at the tested flow rate, differs from the current value of Y by more
than 5 percent, perform a full 3-point recalibration of the meter
using stack gas to determine a new value of Y, and (except as
otherwise provided in section 10.2.2.5 of this method) apply the new
Y value to the data recorded during the field test.
10.2.2.5 Post-Test Calibration Check. Check the calibration of
the gas flow meter following each field test at one intermediate
flow rate setting, either at, or in close proximity to, the average
sample flow rate during the field test. For dry gas meters, ensure
at least three revolutions of the meter during the calibration
check. For mass flow meters, this check must be performed before
leaving the test site, while sampling stack gas. If a one-point
calibration check shows that the value of Yi at the
tested flow rate differs by more than 5 percent from the current
value of Y, repeat the full 3-point calibration procedure to
determine a new value of Y, and apply the new Y value to the gas
volume measurements made with the gas flow meter during the field
test that was just completed. For mass flow meters, perform the 3-
point recalibration while sampling stack gas.
10.3 Thermocouples and Other Temperature Sensors. Use the
procedures and criteria in Section 10.3 of Method 2 in Appendix A-1
to this part to calibrate in-stack temperature sensors and
thermocouples. Dial thermometers shall be calibrated against
mercury-in-glass thermometers. Calibrations must be performed prior
to initial use and before each field test thereafter. At each
calibration point, the absolute temperature measured by the
temperature sensor must agree to within 1.5 percent of
the temperature measured with the reference sensor, otherwise the
sensor may not continue to be used.
[[Page 51524]]
10.4 Barometer. Calibrate against a mercury barometer as per
Section 10.6 of Method 5 in appendix A-3 to this part. Calibration
must be performed prior to initial use and before each test program,
and the absolute pressure measured by the barometer must agree to
within +10 mm Hg of the pressure measured by the mercury barometer,
otherwise the barometer may not continue to be used.
10.5 Other Sensors and Gauges. Calibrate all other sensors and
gauges according to the procedures specified by the instrument
manufacturer(s).
10.6 Analytical System Calibration. See Section 11.1 of this
method.
11.0 Analytical Procedures
The analysis of Hg in the field and quality control samples may
be conducted using any instrument or technology capable of
quantifying total Hg from the sorbent media and meeting the
performance criteria in this method. Because multiple analytical
approaches, equipment and techniques are appropriate for the
analysis of sorbent traps, it is not possible to provide detailed,
technique-specific analytical procedures. As they become available,
detailed procedures for a variety of candidate analytical approaches
will be posted at http://www.epa.gov/ttn/emc.
11.1 Analytical System Calibration. Perform a multipoint
calibration of the analyzer at three or more upscale points over the
desired quantitative range (multiple calibration ranges shall be
calibrated, if necessary). The field samples analyzed must fall
within a calibrated, quantitative range and meet the performance
criteria specified below. For samples suitable for aliquotting, a
series of dilutions may be needed to ensure that the samples fall
within a calibrated range. However, for sorbent media samples
consumed during analysis (e.g., when using thermal desorption
techniques), extra care must be taken to ensure that the analytical
system is appropriately calibrated prior to sample analysis. The
calibration curve range(s) should be determined such that the levels
of Hg mass expected to be collected and measured will fall within
the calibrated range. The calibration curve may be generated by
directly introducing standard solutions into the analyzer or by
spiking the standards onto the sorbent media and then introducing
into the analyzer after preparing the sorbent/standard according to
the particular analytical technique. For each calibration curve, the
value of the square of the linear correlation coefficient, i.e.,
r\2\, must be [gteqt]0.99, and the analyzer response must be within
10 percent of the reference value at each upscale
calibration point. Calibrations must be performed on the day of the
analysis, before analyzing any of the samples. Following
calibration, an independent standard shall be analyzed. The measured
value of the independently prepared standard must be within < plus-
minus>10 percent of the expected value.
11.2 Sample Preparation. Carefully separate the sections of each
sorbent trap. Combine for analysis all materials associated with
each section; any supporting substrate that the sample gas passes
through prior to entering a media section (e.g., glass wool
separators, acid gas traps, etc.) must be analyzed with that
segment.
11.3 Field Sample Analyses. Analyze the sorbent trap samples
following the same procedures that were used for conducting the
Hg\0\ and HgCl2 analytical bias tests. The individual
sections of the sorbent trap and their respective components must be
analyzed separately (i.e., section 1 and its components, then
section 2 and its components). All sorbent trap section 1 sample
analyses must be within the calibrated range of the analytical
system. For wet analyses, the sample can simply be diluted to fall
within the calibrated range. However, for the destructive thermal
analyses, samples that are not within the calibrated range cannot be
re-analyzed. As a result, the sample cannot be validated, and
another sample must be collected. It is strongly suggested that the
analytical system be calibrated over multiple ranges so that
thermally analyzed samples do fall within the calibrated range. The
total mass of Hg measured in each sorbent trap section 1 must also
fall within the lower and upper mass limits established during the
initial Hg\0\ and HgCl2 analytical bias test. If a sample
is analyzed and found to fall outside of these limits, it is
acceptable for an additional Hg\0\ and HgCl2 analytical
bias test to be performed that now includes this level. However,
some samples (e.g., the mass collected in trap section 2 or the mass
collected in trap section 1 when the stack gas concentration is < 0.5
[mu]g/m3), may have Hg levels so low that it may not be possible to
quantify them in the analytical system's calibrated range. Because a
reliable estimate of these low-level Hg measurements is necessary to
fully validate the emissions data, the MDL (see section 8.2.2.1 of
this method) is used to establish the minimum amount that can be
detected and reported. If the measured mass or concentration is
below the lowest point in the calibration curve and above the MDL,
the analyst must do the following: estimate the mass or
concentration of the sample based on the analytical instrument
response relative to an additional calibration standard at a
concentration or mass between the MDL and the lowest point in the
calibration curve. This is accomplished by establishing a response
factor (e.g., area counts per Hg mass or concentration) and
estimating the amount of Hg present in the sample based on the
analytical response and this response factor.
Example: The analysis of a particular sample results in a
measured mass above the MDL, but below the lowest point in the
calibration curve which is 10 ng. An MDL of 1.3 ng Hg has been
established by the MDL study. A calibration standard containing 5 ng
of Hg is analyzed and gives an analytical response of 6,170 area
counts, which equates to a response factor of 1,234 area counts/ng
Hg. The analytical response for the sample is 4,840 area counts.
Dividing the analytical response for the sample (4,840 area counts)
by the response factor gives 3.9 ng Hg, which is the estimated mass
of Hg in the sample.
11.4 Analysis of Continuing Calibration Verification Standard
(CCVS). After no more than 10 samples and at the end of each set of
analyses, a continuing calibration verification standard must be
analyzed. The measured value of the continuing calibration standard
must be within 10 percent of the expected value.
11.5 Blanks. The analysis of blanks is optional. The analysis of
blanks is useful to verify the absence of, or an acceptable level
of, Hg contamination. Blank levels should be considered when
quantifying low Hg levels and their potential contribution to
meeting the sorbent trap section 2 breakthrough requirements;
however, correcting sorbent trap results for blank levels is
prohibited.
12.0 Calculations and Data Analysis
You must follow the procedures for calculation and data analysis
listed in this section.
12.1 Nomenclature. The terms used in the equations are defined
as follows:
B = Breakthrough (%).
Bws = Moisture content of sample gas as measured by
Method 4, percent/100.
Ca = Concentration of Hg for the sample collection
period, for sorbent trap ``a'' ([mu]g/dscm).
Cb = Concentration of Hg for the sample collection
period, for sorbent trap ``b'' ([mu]g/dscm).
Cd = Hg concentration, dry basis ([mu]g/dscm).
Crec = Concentration of spiked compound measured ([mu]g/
m\3\).
Cw = Hg concentration, wet basis ([mu]g/m\3\).
m1 = Mass of Hg measured on sorbent trap section 1
([mu]g).
m2 = Mass of Hg measured on sorbent trap section 2
([mu]g).
mrecovered = Mass of spiked Hg recovered in Analytical
Bias or Field Recovery Test ([mu]g).
ms = Total mass of Hg measured on spiked trap in Field
Recovery Test ([mu]g).
mspiked = Mass of Hg spiked in Analytical Bias or Field
Recovery Test ([mu]g).
mu = Total mass of Hg measured on unspiked trap in Field
Recovery Test ([mu]g).
R = Percentage of spiked mass recovered (%).
RD = Relative deviation between the Hg concentrations from traps
``a'' and ``b'' (%).
vs = Volume of gas sampled, spiked trap in Field Recovery
Test (dscm).
Vt = Total volume of dry gas metered during the
collection period (dscm); for the purposes of this method, standard
temperature and pressure are defined as 20 [deg]C and 760 mm Hg,
respectively.
vu = Volume of gas sampled, unspiked trap in Field
Recovery Test (dscm).
12.2 Calculation of Spike Recovery (Analytical Bias Test).
Calculate the percent recovery of Hg\0\ and HgCl2 using
Equation 30B-1.
[GRAPHIC] [TIFF OMITTED] TR07SE07.028
12.3 Calculation of Breakthrough. Use Equation 30B-2 to
calculate the percent breakthrough to the second section of the
sorbent trap.
[GRAPHIC] [TIFF OMITTED] TR07SE07.029
[[Page 51525]]
12.4 Calculation of Hg Concentration. Calculate the Hg
concentration measured with sorbent trap ``a'', using Equation 30B-
3.
[GRAPHIC] [TIFF OMITTED] TR07SE07.030
For sorbent trap ``b'', replace ``Ca '' with
``Cb '' in Equation 30B-3. Report the average
concentration, i.e., \1/2\ (Ca + Cb).
12.5 Moisture Correction. Use Equation 30B-4 if your
measurements need to be corrected to a wet basis.
[GRAPHIC] [TIFF OMITTED] TR07SE07.031
12.6 Calculation of Paired Trap Agreement. Calculate the
relative deviation (RD) between the Hg concentrations measured with
the paired sorbent traps using Equation 30B-5.
[GRAPHIC] [TIFF OMITTED] TR07SE07.032
12.7 Calculation of Measured Spike Hg Concentration (Field
Recovery Test). Calculate the measured spike concentration using
Equation 30B-6.
[GRAPHIC] [TIFF OMITTED] TR07SE07.033
Then calculate the spiked Hg recovery, R, using Equation 30B-7.
[GRAPHIC] [TIFF OMITTED] TR07SE07.034
13.0 Method Performance
How do I validate my data? Measurement data are validated using
initial, one-time laboratory tests coupled with test program-
specific tests and procedures. The analytical matrix interference
test and the Hg\0\ and HgCl2 analytical bias test
described in Section 8.2 are used to verify the appropriateness of
the selected analytical approach(es) as well as define the valid
working ranges for sample analysis. The field recovery test serves
to verify the performance of the combined sampling and analysis as
applied for each test program. Field test samples are validated by
meeting the above requirements as well as meeting specific sampling
requirements (i.e., leak checks, paired train agreement, total
sample volume agreement with field recovery test samples) and
analytical requirements (i.e., valid calibration curve, continuing
calibration performance, sample results within calibration curve and
bounds of Hg\0\ and HgCl2 analytical bias test). Complete
data validation requirements are summarized in Table 9-1.
14.0 Pollution Prevention [Reserved]
15.0 Waste Management [Reserved]
16.0 References
1. EPA Traceability Protocol for Qualification and Certification
of Elemental Mercury Gas Generators, expected publication date
December 2008, see http://www.epa.gov/ttn/emc.
2. EPA Traceability Protocol for Qualification and Certification
of Oxidized Mercury Gas Generators, expected publication date
December 2008, see http://www.epa.gov/ttn/emc.
3. EPA Traceability Protocol for Assay and Certification of
Gaseous Calibration Standards, expected revision publication date
December 2008, see http://www.epa.gov/ttn/emc.
17.0 Figures and Tables
BILLING CODE 6560-50-C
[[Page 51526]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.026
[[Page 51527]]
Appendix B [Amended]
0
3. Amend Performance Specification 12A in Appendix B to part 60 by
revising sections 8.6.2, 8.6.4, 8.6.5, and 8.6.6.1 to read as follows:
Performance Specification 12A--Specifications and Test Procedures for
Total Vapor Phase Mercury Continuous Emission Monitoring Systems in
Stationary Sources
* * * * *
8.6.2 RM. Unless otherwise specified in an applicable subpart of
the regulations, use Method 29, Method 30A, or Method 30B in
appendix A to this part or American Society of Testing and Materials
(ASTM) Method D6784-02 (incorporated by reference, see Sec. 60.17)
as the RM for Hg concentration. Do not include the filterable
portion of the sample when making comparisons to the CEMS results.
When Method 29, Method 30B, or ASTM D6784-02 is used, conduct the RM
test runs with paired or duplicate sampling systems. When Method 30A
is used, paired sampling systems are not required. If the RM and
CEMS measure on a different moisture basis, data derived with Method
4 in appendix A to this part shall also be obtained during the RA
test.
* * * * *
8.6.4 Number and Length of RM and Tests. Conduct a minimum of
nine RM test runs. When Method 29, Method 30B, or ASTM D6784-02 is
used, only test runs for which the paired RM trains meet the
relative deviation criteria (RD) of this PS shall be used in the RA
calculations. In addition, for Method 29 and ASTM D6784-02, use a
minimum sample time of 2 hours and for Method 30A use a minimum
sample time of 30 minutes.
Note: More than nine sets of RM tests may be performed. If this
option is chosen, paired RM test results may be excluded so long as
the total number of paired RM test results used to determine the
CEMS RA is greater than or equal to nine. However, all data must be
reported including the excluded data.
8.6.5 Correlation of RM and CEMS Data. Correlate the CEMS and
the RM test data as to the time and duration by first determining
from the CEMS final output (the one used for reporting) the
integrated average pollutant concentration for each RM test period.
Consider system response time, if important, and confirm that the
results are on a consistent moisture basis with the RM test. Then,
compare each integrated CEMS value against the corresponding RM
value. When Method 29, Method 30A, Method 30B, or ASTM D6784-02 is
used, compare each CEMS value against the corresponding average of
the paired RM values.
8.6.6 * * *
8.6.6.1 When Method 29, Method 30B, or ASTM D6784-02 is used,
outliers are identified through the determination of relative
deviation (RD) of the paired RM tests. Data that do not meet the
criteria should be flagged as a data quality problem. The primary
reason for performing paired RM sampling is to ensure the quality of
the RM data. The percent RD of paired data is the parameter used to
quantify data quality. Determine RD for two paired data points as
follows:
[GRAPHIC] [TIFF OMITTED] TR07SE07.035
where Ca and Cb are concentration values
determined from each of the two samples, respectively.
* * * * *
PART 72--PERMITS REGULATION
0
4. The authority citation for part 72 continues to read as follows:
Authority: 42 U.S.C. 7601 and 7651, et seq.
0
5. Revise the definition of ``sorbent trap monitoring system'' in Sec.
72.2 as follows:
Sec. 72.2 Definitions.
* * * * *
Sorbent trap monitoring system means the equipment required by part
75 of this chapter for the continuous monitoring of Hg emissions, using
paired sorbent traps containing iodated charcoal (IC) or other suitable
reagents. This excepted monitoring system consists of a probe, the
paired sorbent traps, an umbilical line, moisture removal components,
an air tight sample pump, a gas flow meter, and an automated data
acquisition and handling system. The monitoring system samples the
stack gas at a rate proportional to the stack gas volumetric flowrate.
The sampling is a batch process. Using the sample volume measured by
the gas flow meter and the results of the analyses of the sorbent
traps, the average mercury concentration in the stack gas for the
sampling period is determined, in units of micrograms per dry standard
cubic meter ([mu]g/dscm). Mercury mass emissions for each hour in the
sampling period are calculated using the average Hg concentration for
that period, in conjunction with contemporaneous hourly measurements of
the stack gas flow rate, corrected for the stack moisture content.
* * * * *
PART 75--CONTINUOUS EMISSION MONITORING
0
6. The authority citation for part 75 continues to read as follows:
Authority: 42 U.S.C. 7601, 7651k, and 7651k note.
0
7. Amend Sec. 75.15 as follows:
0
a. Revise paragraph (f);
0
b. Revise paragraph (i); and
0
c. Add new paragraph (k).
The revisions and additions read as follows:
Sec. 75.15 Special provisions for measuring Hg mass emissions using
the excepted sorbent trap monitoring methodology.
* * * * *
(f) At the beginning and end of each sample collection period, and
at least once in each unit operating hour during the collection period,
the gas flow meter reading shall be recorded.
* * * * *
(i) All unit operating hours for which valid Hg concentration data
are obtained with the primary sorbent trap monitoring system (as
verified using the quality assurance procedures in appendix K to this
part) shall be reported in the electronic quarterly report under Sec.
75.84(f). For hours in which data from the primary monitoring system
are invalid, the owner or operator may, in accordance with Sec.
75.20(d), report valid Hg concentration data from: A certified
redundant backup CEMS or sorbent trap monitoring system; a certified
non-redundant backup CEMS or sorbent trap monitoring system; or an
applicable reference method under Sec. 75.22. If no quality-assured Hg
concentration are available for a particular hour, the owner or
operator shall report the appropriate substitute data value in
accordance with Sec. 75.39.
* * * * *
(k) During each RATA of a sorbent trap monitoring system, the type
of sorbent material used by the traps shall be the same as for daily
operation of the monitoring system. A new pair of traps shall be used
for each RATA run. However, the size of the traps used for the RATA may
be smaller than the traps used for daily operation of the system.
* * * * *
0
8. Amend Sec. 75.20 by adding new paragraph (d)(2)(ix) to read as
follows:
Sec. 75.20 Initial certification and recertification procedures.
* * * * *
(d)* * *
(2)* * *
(ix) For non-redundant backup Hg CEMS and sorbent trap monitoring
systems, and for like-kind replacement Hg analyzers, the following
provisions apply in addition to, or, in some cases, in lieu of, the
general requirements in paragraphs (d)(2)(i) through (d)(2)(viii) of
this section:
(A) When a certified sorbent trap monitoring system is brought into
service as a regular non-redundant backup monitoring system, the system
shall be operated according to the procedures in Sec. 75.15 and
appendix K of this part;
(B) When a regular non-redundant backup Hg CEMS or a like-kind
[[Page 51528]]
replacement Hg analyzer is brought into service, a linearity check with
elemental Hg standards, as described in paragraph (c)(1)(ii) of this
section and section 6.2 of appendix A of this part, and a single-point
system integrity check, as described in section 2.6 of appendix B of
this part, shall be performed. Alternatively, a 3-level system
integrity check, as described in paragraph (c)(1)(vi) of this section
and paragraph (g) of section 6.2 in appendix A of this part, may be
performed in lieu of these two tests.
(C) The weekly single-point system integrity checks described in
section 2.6 of appendix B of this part are required as long as a non-
redundant backup Hg CEMS or like-kind replacement Hg analyzer remains
in service, unless the daily calibrations of the Hg analyzer are done
using a NIST-traceable source of oxidized Hg.
* * * * *
0
9. Amend Sec. 75.57 by revising paragraph (j)(7) to read as follows:
Sec. 75.57 General recordkeeping provisions.
* * * * *
(j) * * *
(7) Record the gas flow meter reading (in dscm, rounded to the
nearest hundreth) at the beginning and end of the collection period and
at least once in each unit operating hour during the collection period.
* * * * *
0
10. Amend Sec. 75.81 by revising paragraph (a)(1) to read as follows:
Sec. 75.81 Monitoring of Hg mass emissions and heat input at the unit
level.
* * * * *
(a) * * *
(1) A Hg concentration monitoring system (as defined in Sec. 72.2
of this chapter) or a sorbent trap monitoring system (as defined in
Sec. 72.2 of this chapter), to measure the mass concentration of total
vapor phase Hg in the flue gas, including the elemental and oxidized
forms of Hg, in micrograms per standard cubic meter ([mu]g/scm); and
* * * * *
0
11. Amend Sec. 75.84 by revising paragraph (f)(1)(ii)(J) to read as
follows:
Sec. 75.84 Recordkeeping and Reporting.
* * * * *
(f) * * *
(1) * * *
(ii) * * *
(J) For units using sorbent trap monitoring systems, the hourly gas
flow meter readings taken between the initial and final meter readings
for the data collection period; and
* * * * *
Appendix A to Part 75--[Amended]
0
12. Amend Appendix A to part 75 by removing the twentieth sentence in
paragraph (a) of section 6.5.7 which currently reads ``For the RATA of
a sorbent trap monitoring system, use the same size trap that is used
for daily operation of the monitoring system.'' and adding in its place
``For the RATA of a sorbent trap monitoring system, the type of sorbent
material used by the traps shall be the same as for daily operation of
the monitoring system; however, the size of the traps used for the RATA
may be smaller than the traps used for daily operation of the
system.''.
0
13. Amend Appendix B to part 75 by revising section 1.5.2 to read as
follows:
Appendix B to Part 75--Quality Assurance and Quality Control Procedures
* * * * *
1.5.2 Monitoring System Integrity and Data Quality
Explain the procedures used to perform the leak checks when
sorbent traps are placed in service and removed from service. Also
explain the other QA procedures used to ensure system integrity and
data quality, including, but not limited to, gas flow meter
calibrations, verification of moisture removal, and ensuring air-
tight pump operation. In addition, the QA plan must include the data
acceptance and quality control criteria in section 8 of appendix K
to this part. All reference meters used to calibrate the gas flow
meters (e.g., wet test meters) shall be periodically recalibrated.
Annual, or more frequent, recalibration is recommended. If a NIST-
traceable calibration device is used as a reference flow meter, the
QA plan must include a protocol for ongoing maintenance and periodic
recalibration to maintain the accuracy and NIST-traceability of the
calibrator.
* * * * *
0
14. Amend Appendix K to part 75 as follows:
0
a. Amend section 5.1 by revising Figure K-1;
0
b. Revise section 5.1.3;
0
c. Revise section 5.1.5;
0
d. Revise section 7.1.3;
0
e. Revise section 7.2.3;
0
f. Revise section 7.2.5;
0
g. Amend section 8.0 by revising Table K-1;
0
h. Revise section 9.2;
0
i. Revise section 10.4;
0
j. Remove and reserve section 11.5;
0
k. Revise section 11.6; and
0
l. Revise section 11.7.
The revisions and additions read as follows:
Appendix K to Part 75--Quality Assurance and Operating Procedures for
Sorbent Trap Monitoring Systems
* * * * *
5.1 * * *
BILLING CODE 6560-50-C
[[Page 51529]]
[GRAPHIC] [TIFF OMITTED] TR07SE07.027
[[Page 51530]]
* * * * *
5.1.3 Moisture Removal Device
A robust moisture removal device or system, suitable for
continuous duty (such as a Peltier cooler), shall be used to remove
water vapor from the gas stream prior to entering the gas flow
meter.
* * * * *
5.1.5 Gas Flow Meter
A gas flow meter (such as a dry gas meter, thermal mass flow
meter, or other suitable measurement device) shall be used to
determine the total sample volume on a dry basis, in units of
standard cubic meters. The meter must be sufficiently accurate to
measure the total sample volume to within 2 percent and must be
calibrated at selected flow rates across the range of sample flow
rates at which the sorbent trap monitoring system typically
operates. The gas flow meter shall be equipped with any necessary
auxiliary measurement devices (e.g., temperature sensors, pressure
measurement devices) needed to correct the sample volume to standard
conditions.
* * * * *
7.1.3 Pre-test Leak Check
Perform a leak check with the sorbent traps in place. Draw a
vacuum in each sample train. Adjust the vacuum in the sample train
to ~15[sec] Hg. Using the gas flow meter, determine leak rate. The
leakage rate must not exceed 4 percent of the target sampling rate.
Once the leak check passes this criterion, carefully release the
vacuum in the sample train then seal the sorbent trap inlet until
the probe is ready for insertion into the stack or duct.
* * * * *
7.2.3 Flow Rate Control
Set the initial sample flow rate at the target value from
section 7.1.1 of this appendix. Record the initial gas flow meter
reading, stack temperature (if needed to convert to standard
conditions), meter temperatures (if needed), etc. Then, for every
operating hour during the sampling period, record the date and time,
the sample flow rate, the gas flow meter reading, the stack
temperature (if needed), the flow meter temperatures (if needed),
temperatures of heated equipment such as the vacuum lines and the
probes (if heated), and the sampling system vacuum readings. Also,
record the stack gas flow rate, as measured by the certified flow
monitor, and the ratio of the stack gas flow rate to the sample flow
rate. Adjust the sampling flow rate to maintain proportional
sampling, i.e., keep the ratio of the stack gas flow rate to sample
flow rate constant, to within 25 percent of the
reference ratio from the first hour of the data collection period
(see section 11 of this appendix).
* * * * *
7.2.5 Essential Operating Data
Obtain and record any essential operating data for the facility
during the test period, e.g., the barometric pressure for correcting
the sample volume measured by a dry gas meter to standard
conditions. At the end of the data collection period, record the
final gas flow meter reading and the final values of all other
essential parameters.
* * * * *
8.0 * * *
Table K-1.--Quality Assurance/Quality Control Criteria for Sorbent Trap Monitoring Systems
----------------------------------------------------------------------------------------------------------------
QA/QC test or specification Acceptance criteria Frequency Consequences if not met
----------------------------------------------------------------------------------------------------------------
Pre-test leak check.................. < =4% of target sampling Prior to Sampling...... Sampling shall not
rate. commence until the
leak check is passed.
Post-test leak check................. < =4% of average After sampling......... Sample check
sampling rate. invalidated.**
Ratio of stack gas flow rate to Maintain within < plus- Every hour throughout Case-by-case
sample flow rate. minus>25% of initial data collection period. evaluation.
ratio from first hour
of data collection
period.
Sorbent trap section 2 breakthrough.. < =5% of Section 1 Hg Every sample........... Sample invalidated.**
mass.
Paired sorbent trap agreement........ < =10% Relative Every sample........... Sample invalidated.**
Deviation (RD).
Spike recovery study................. Average recovery Prior to analyzing Field samples shall not
between 85% and 115% field samples and be analyzed until the
for each of the 3 prior to use of new percent recovery
spike concentration sorbent media. criterion has been
levels. met.
Multipoint analyzer calibration...... Each analyzer reading On the day of analysis, Recalibrate until
within 10% before analyzing any successful.
of true value and r\2\ samples.
>=0.99.
Analysis of independent calibration Within 10% Following daily Recalibrate and repeat
standard. of true value. calibration, prior to independent standard
analyzing field. analysis samples until
successful.
Spike recovery from section 3 of 75-125% of spike amount Every sample........... Sample invalidated.**
sorbent trap.
RATA................................. RA < =20.0% or Mean For initial Data from the system
difference < =1.0 certification and are invalidated until
[mu]gm/dscm for low annually thereafter. a RATA is passed.
emitters.
Gas flow meter calibration (At 3 Calibration factor (Y) Prior to initial use Recalibrate the meter
settings initially, and 1 setting within 5% and at least quarterly at three settings to
thereafter). of average value from thereafter. determine a new value
the initial (3-point) of Y.
calibration.
Temperature sensor calibration....... Absolute temperature Prior to initial use Recalibrate. Sensor may
measured by sensor and at least quarterly not be used until
within < plus- thereafter. specification is met.
minus>1.5% of a
reference sensor.
Barometer calibration................ Absolute pressure Prior to initial use Recalibrate. Instrument
measured by instrument and at least quarterly may not be used until
within 10 thereafter. specification is met.
mm Hg of reading with
a mercury barometer.
----------------------------------------------------------------------------------------------------------------
** And data from the pair of sorbent traps are also invalidated.
* * * * *
9.2 Gas Flow Meter Calibration
9.2.1 Preliminaries. The manufacturer or supplier of the gas
flow meter should perform all necessary set-up, testing,
programming, etc., and should provide the end user with any
necessary instructions, to ensure that the meter will give an
accurate readout of dry gas volume in standard cubic meters for the
particular field application.
9.2.2 Initial Calibration. Prior to its initial use, a
calibration of the flow meter shall be performed. The initial
calibration may be done by the manufacturer, by the equipment
supplier, or by the end user. If the flow meter is volumetric in
nature (e.g., a dry gas meter), the manufacturer, equipment
supplier, or end user may perform a direct volumetric calibration
using any gas. For a mass flow meter, the manufacturer, equipment
supplier, or end user may calibrate the meter using a bottled gas
mixture containing 12 0.5% CO2, 7 0.5% O2, and balance N2, or these
[[Page 51531]]
same gases in proportions more representative of the expected stack
gas composition. Mass flow meters may also be initially calibrated
on-site, using actual stack gas.
9.2.2.1 Initial Calibration Procedures. Determine an average
calibration factor (Y) for the gas flow meter, by calibrating it at
three sample flow rate settings covering the range of sample flow
rates at which the sorbent trap monitoring system typically
operates. You may either follow the procedures in section 10.3.1 of
Method 5 in appendix A-3 to part 60 of this chapter or the
procedures in section 16 of Method 5 in appendix A-3 to part 60 of
this chapter. If a dry gas meter is being calibrated, use at least
five revolutions of the meter at each flow rate.
9.2.2.2 Alternative Initial Calibration Procedures.
Alternatively, you may perform the initial calibration of the gas
flow meter using a reference gas flow meter (RGFM). The RGFM may
either be: (1) A wet test meter calibrated according to section
10.3.1 of Method 5 in appendix A-3 to part 60; (2) a gas flow
metering device calibrated at multiple flow rates using the
procedures in section 16 of Method 5 in appendix A-3 to part 60; or
(3) a NIST-traceable calibration device capable of measuring
volumetric flow to an accuracy of 1 percent. To calibrate the gas
flow meter using the RGFM, proceed as follows: While the sorbent
trap monitoring system is sampling the actual stack gas or a
compressed gas mixture that simulates the stack gas composition (as
applicable), connect the RGFM to the discharge of the system. Care
should be taken to minimize the dead volume between the sample flow
meter being tested and the RGFM. Concurrently measure dry gas volume
with the RGFM and the flow meter being calibrated the for a minimum
of 10 minutes at each of three flow rates covering the typical range
of operation of the sorbent trap monitoring system. For each 10-
minute (or longer) data collection period, record the total sample
volume, in units of dry standard cubic meters (dscm), measured by
the RGFM and the gas flow meter being tested.
9.2.2.3 Initial Calibration Factor. Calculate an individual
calibration factor Yi at each tested flow rate from
section 9.2.2.1 or 9.2.2.2 of this appendix (as applicable), by
taking the ratio of the reference sample volume to the sample volume
recorded by the gas flow meter. Average the three Yi
values, to determine Y, the calibration factor for the flow meter.
Each of the three individual values of Yi must be within
0.02 of Y. Except as otherwise provided in sections
9.2.2.4 and 9.2.2.5 of this appendix, use the average Y value from
the three level calibration to adjust all subsequent gas volume
measurements made with the gas flow meter.
9.2.2.4 Initial On-Site Calibration Check. For a mass flow meter
that was initially calibrated using a compressed gas mixture, an on-
site calibration check shall be performed before using the flow
meter to provide data for this part. While sampling stack gas, check
the calibration of the flow meter at one intermediate flow rate
typical of normal operation of the monitoring system. Follow the
basic procedures in section 9.2.2.1 or 9.2.2.2 of this appendix. If
the on-site calibration check shows that the value of Yi,
the calibration factor at the tested flow rate, differs by more than
5 percent from the value of Y obtained in the initial calibration of
the meter, repeat the full 3-level calibration of the meter using
stack gas to determine a new value of Y, and apply the new Y value
to all subsequent gas volume measurements made with the gas flow
meter.
9.2.2.5 Ongoing Quality Assurance. Recalibrate the gas flow
meter quarterly at one intermediate flow rate setting representative
of normal operation of the monitoring system. Follow the basic
procedures in section 9.2.2.1 or 9.2.2.2 of this appendix. If a
quarterly recalibration shows that the value of Yi, the
calibration factor at the tested flow rate, differs from the current
value of Y by more than 5 percent, repeat the full 3-level
calibration of the meter to determine a new value of Y, and apply
the new Y value to all subsequent gas volume measurements made with
the gas flow meter.
* * * * *
10.4 Field Sample Analysis
Analyze the sorbent trap samples following the same procedures
that were used for conducting the spike recovery study. The three
sections of each sorbent trap must be analyzed separately (i.e.,
section 1, then section 2, then section 3). Quantify the total mass
of Hg for each section based on analytical system response and the
calibration curve from section 10.1 of this appendix. Determine the
spike recovery from sorbent trap section 3. The spike recovery must
be no less than 75 percent and no greater than 125 percent. To
report the final Hg mass for each trap, add together the Hg masses
collected in trap sections 1 and 2.
* * * * *
11.5 [Reserved]
11.6 Calculation of Hg Concentration
Calculate the Hg concentration for each sorbent trap, using the
following equation:
[GRAPHIC] [TIFF OMITTED] TR07SE07.036
Where:
C = Concentration of Hg for the collection period, ([mu]gm/dscm)
M\*\ = Total mass of Hg recovered from sections 1 and 2 of the
sorbent trap, ([mu]g)
Vt = Total volume of dry gas metered during the
collection period, (dscm). For the purposes of this appendix,
standard temperature and pressure are defined as 20 [deg]C and 760
mm Hg, respectively.
11.7 Calculation of Paired Trap Agreeement
Calculate the relative deviation (RD) between the Hg
concentrations measured with the paired sorbent traps:
[GRAPHIC] [TIFF OMITTED] TR07SE07.037
Where:
RD = Relative deviation between the Hg concentrations from traps
``a'' and ``b'' (percent)
Ca = Concentration of Hg for the collection period, for
sorbent trap ``a'' ([mu]gm/dscm)
Cb = Concentration of Hg for the collection period, for
sorbent trap ``b'' ([mu]gm/dscm)
* * * * *
[FR Doc. 07-4147 Filed 9-6-07; 8:45 am]
BILLING CODE 6560-50-P