[Federal Register Volume 64, Number 109 (Tuesday, June 8, 1999)]
[Rules and Regulations]
[Pages 30417-30434]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14220]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 136
[FRL-6354-3]
RIN 2040-AD07
Guidelines Establishing Test Procedures for the Analysis of
Pollutants; Measurement of Mercury in Water (EPA Method 1631, Revision
B); Final Rule
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: This final regulation amends the ``Guidelines Establishing
Test Procedures for the Analysis of Pollutants'' under section 304(h)
of the Clean Water Act by adding EPA Method 1631, Revision B: Mercury
in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic
Fluorescence Spectrometry. EPA Method 1631 measures mercury at the low
levels associated with ambient water quality criteria (WQC). EPA has
promulgated WQC for mercury at 12 parts-per-trillion (ppt) in the
National Toxics Rule, and published a criterion for mercury at 1.3 ppt
in the Water Quality Guidance for the Great Lakes System. The version
of Method 1631 promulgated today includes changes to the method based
on public comments at proposal (63 FR 28867, May 26, 1998). These
changes increase measurement reliability at WQC levels. EPA recommends
the use of clean sampling and laboratory techniques in conjunction with
EPA Method 1631 to preclude contamination
[[Page 30418]]
at the low ppt levels necessary for mercury determinations. EPA has
published guidance documents on sampling and clean rooms for trace
metals, including mercury.
EFFECTIVE DATE: This regulation is effective July 8, 1999. For judicial
review purposes, this final rule is promulgated as of 1:00 p.m. Eastern
Standard Time on June 22, 1999 in accordance with 40 CFR 23.7.
The incorporation by reference of EPA Method 1631 is approved by
the Director of the Federal Register July 8, 1999.
ADDRESSES: Copies of the public comments received, EPA responses, and
all other supporting documents (including references included in this
notice) are available for review at the U.S. Environmental Protection
Agency, Water Docket, 401 M Street SW, Washington, DC 20460. For access
to docket materials, call 202/260-3027 on Monday through Friday,
excluding Federal holidays, between 9 a.m. and 3:30 p.m. Eastern
Standard Time for an appointment.
Copies of EPA Method 1631 are available from the National Technical
Information Service (NTIS), 5285 Port Royal Road, Springfield, VA
22161, (703) 605-6000 or (800) 553-6847. The NTIS publication number is
PB99-131989.
An electronic version of EPA Method 1631 also is available via the
Internet at http://www.epa.gov/OST/Methods.
FOR FURTHER INFORMATION CONTACT: For information regarding EPA Method
1631 contact Maria Gomez-Taylor, Ph.D., Engineering and Analysis
Division (4303), USEPA Office of Science and Technology, 401 M Street,
SW, Washington, DC 20460; or call 202/260-1639.
SUPPLEMENTARY INFORMATION:
Potentially Regulated Entities
EPA Regions, as well as States, Territories and Tribes authorized
to implement the National Pollutant Discharge Elimination System
(NPDES) program, issue permits that comply with the technology-based
and water quality-based requirements of the Clean Water Act. In doing
so, the NPDES permitting authority, including authorized States,
Territories, and Tribes, make a number of discretionary choices
associated with permit writing, including the selection of pollutants
to be measured and, in many cases, limited in permits. If EPA has
``approved'' standardized testing procedures (i.e., promulgated through
rulemaking) for a given pollutant, the NPDES permit must include one of
the approved testing procedures or an approved alternate test
procedure. Regulatory entities may, at their discretion, require use of
this method in their permits. Therefore, entities with NPDES permits
could be affected by the standardization of testing procedures in this
rulemaking, because NPDES permits may incorporate the testing
procedures in today's rulemaking. In addition, when a State, Territory,
or authorized Tribe provides certification of federal licenses under
Clean Water Act section 401, States, Territories and Tribes are
directed to use the standardized testing procedures. Categories and
entities that may ultimately be affected include:
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Examples of potentially
Category regulated entities
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Regional, State and Territorial States, Territories, and Tribes
Governments and Indian Tribes. authorized to administer the
NPDES permitting program;
States, Territories, and
Tribes providing certification
under Clean Water Act section
401; Governmental NPDES
permittees.
Industry............................... Industrial NPDES permittees.
Municipalities......................... Publicly-owned treatment works
with NPDES permits.
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This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
action. This table lists the types of entities that EPA is now aware
could potentially be affected by this action. Other types of entities
not listed in the table could also be affected. If you have questions
regarding the applicability of this action to a particular entity,
consult the person listed in the preceding FOR FURTHER INFORMATION
CONTACT section.
Outline of Preamble
I. Authority
II. Background
III. Summary of Final Rule
A. Introduction
B. Summary of EPA Method 1631
C. Sample Contamination
D. Quality Control
E. Performance-Based Measurement System
IV. Changes to EPA Method 1631 Since Proposal
A. Holding Time Change
B. Performance Criteria Change
C. Reporting Requirements Changes
1. Reporting of data that failed to meet QC acceptance criteria
2. Reporting of blank results
3. Reporting laboratory-specific MDLs and MLs
D. Other Changes and Improvements
1. Changes to method implementation
2. Corrections to method
3. Clarifying statements
4. Additions to health and safety monitoring and waste
management
V. Public Participation and Response to Comments
1. Support for EPA Method 1631
2. Practicality and cost
3. EPA Method 1631 represents a significant regulatory action
4. Regulatory implications
5. Retention of approved methods and approval of additional
methods
6. Application to wastewater matrices
7. Detection and quantitation
8. Clean techniques
9. Corrections to statements in proposal
10. Quality control
11. Blanks and contamination
12. Validation study
13. Technical details of EPA Method 1631
14. Miscellaneous
VI. Regulatory Requirements
A. Executive Order 12866
B. Unfunded Mandates Reform Act
C. Regulatory Flexibility Act
D. Paperwork Reduction Act
E. Submission to Congress and the General Accounting Office
F. National Technology Transfer and Advancement Act
G. Executive Order 13045
H. Executive Order 12875
I. Executive Order 13084
I. Authority
Today's regulation is being promulgated pursuant to the authority
of sections 301, 304(h), and 501(a) of the Clean Water Act (CWA), 33
U.S.C. 1314(h), 1361(a) (the ``Act''). Section 301 of the Act prohibits
the discharge of any pollutant into navigable waters unless the
discharge complies with a National Pollutant Discharge Elimination
System (NPDES) permit issued under section 402 of the Act. Section
304(h) of the Act requires the Administrator of the EPA to ``promulgate
guidelines establishing test procedures for the analysis of pollutants
that shall include the factors which must be provided in any
certification pursuant to section 401 of this Act or permit
applications pursuant to section 402 of this Act.'' Section 501(a) of
the Act authorizes the Administrator to
[[Page 30419]]
``prescribe such regulations as are necessary to carry out his function
under this Act.'' EPA publishes CWA analytical method regulations at 40
CFR part 136. The Administrator also has made these test procedures
applicable to monitoring and reporting of NPDES permits (40 CFR part
122, Secs. 122.21, 122.41, 122.44, and 123.25), and implementation of
the pretreatment standards issued under section 307 of the Act (40 CFR
part 403, Secs. 403.10 and 402.12).
II. Background
The details of EPA Method 1631 and its use in mercury
determinations were given at proposal on May 26, 1998 (63 FR 28867). On
March 5, 1999, EPA published a notice of data availability (NODA) with
results from additional studies of municipal and industrial effluents
using EPA Method 1631 (64 FR 10596). EPA conducted the additional
studies in order to better respond to comments received on the May 26,
1998 proposal.
III. Summary of Final Rule
A. Introduction
Today's action makes available at 40 CFR part 136 an additional
test procedure for measurement of mercury in aqueous samples. This
rulemaking does not repeal any of the currently approved methods that
measure mercury. For an NPDES permit, the permitting authority should
decide the appropriate method based on the circumstances of the
particular water sample measured. Use of EPA Method 1631 may be
specified by the permitting authority when a permit is modified or
reissued.
EPA does not intend for Method 1631 to be a de facto replacement
for Method 245.1 or any of the other existing EPA-approved methods for
measurement of mercury. EPA intends that permit writers specify the use
of Method 1631 when measurement at very low levels is required, for
example, to determine compliance with water quality-based effluent
limitations duly established at very low levels.
B. Summary of EPA Method 1631
EPA Method 1631 has four procedural components: sample
pretreatment; purge and trap; desorption; and detection by atomic
fluorescence. In the sample pretreatment step, bromine monochloride
(BrCl) is added to the sample to oxidize all forms of mercury to
Hg(II). After oxidation, the sample is sequentially prereduced with
NH2OHHCl to destroy free
halogens, then reduced with SnCl2
to convert Hg(II) to volatile Hg(0). The Hg(0) is purged from the
aqueous solution with nitrogen onto a gold-coated sand trap. The
trapped mercury is thermally desorbed from the gold trap into a flowing
gas stream into the cell of a cold-vapor atomic fluorescence
spectrometer. Quality is assured through calibration and testing of the
oxidation, purging, and detection systems.
C. Sample Contamination
Trace levels of metals are ubiquitous in the environment.
Therefore, the determination of trace metals at the levels of interest
for water quality criteria necessitates the use of clean sample
handling techniques to avoid ``false positive'' test results due to
contamination in the course of sample collection, handling, or
analysis. EPA has distributed several guidance documents that are
designed to ensure that data results from the measurement of metals in
aqueous test samples accurately reflect actual environmental levels.
The guidance documents include: Method 1669: Sampling Ambient Water for
Trace Metals at EPA Water Quality Criteria Levels (Sampling Guidance),
EPA-821-R-96-001, July 1996; Guidance on Establishing Trace Metals
Clean Rooms in Existing Facilities, EPA-821-B-96-001, January 1996; and
Guidance on Documentation and Evaluation of Trace Metals Data Collected
for Clean Water Act Compliance Monitoring, EPA-821-B-96-004, July 1996.
The most serious problem faced by laboratories conducting metals
analyses at these very low levels is the potential for sample
contamination during sample collection and handling. Sample
contamination with mercury is particularly difficult to control because
of its ubiquity in the environment. For example, commonly used
polyethylene sample containers are unacceptable for sample storage
because atmospheric mercury may diffuse through the walls of the
container causing sample contamination. The Sampling Guidance details
rigorous sample handling and quality control (QC) procedures to assure
that reliable data are obtained for mercury at the levels of interest
for water quality criteria. EPA recommends that the procedures
described in the Sampling Guidance be followed when performing low
level, trace metals analyses and has incorporated certain essential
elements of the Guidance in the method.
D. Quality Control
EPA Method 1631 contains all of the standardized QC tests proposed
in EPA's streamlining initiative (62 FR 14976, March 28, 1997) and used
in test procedures in 40 CFR part 136, appendix A. Today's rule
requires an initial demonstration of laboratory capability which
consists of: (1) A method detection limit (MDL) study to demonstrate
that the laboratory is able to achieve the MDL and minimum level of
quantification (ML) specified in EPA Method 1631; and (2) an initial
precision and recovery (IPR) test, consisting of analyses of four
reagent water samples spiked with mercury, to demonstrate the
laboratory's ability to generate acceptable precision and recovery.
Today's rule also requires ongoing QC tests for each analytical
batch, (i.e., a set of 20 samples or less pretreated at the same time):
Verification of calibration of the purge and trap and
atomic fluorescence systems to assure that instrument response has not
deviated significantly from the instrument response obtained during
calibration.
Analysis of a matrix spike (MS) and matrix spike duplicate
(MSD) to demonstrate method accuracy and precision and to monitor
matrix interferences.
Analysis of reagent and bubbler blanks to demonstrate
freedom from contamination.
Analysis of a quality control sample (QCS) and ongoing
precision and recovery (OPR) samples to demonstrate that the method
remains under control.
EPA Method 1631 contains QC acceptance criteria for all QC tests.
Compliance with these criteria will allow a data user to evaluate the
quality of the results. These QC acceptance criteria will increase the
reliability of results and provide a means for laboratories and data
users to monitor analytical performance, thereby providing a basis for
sound, defensible data.
E. Performance Based Measurement System
On March 28, 1997, EPA proposed a rule (62 FR 14976) to streamline
approval procedures and use of analytic methods in water programs
through implementation of a performance-based approach to environmental
measurements. On October 7, 1997, EPA published a document of the
Agency's intent to implement a Performance Based Measurement System
(PBMS) in all media programs to the extent feasible (62 FR 52098).
EPA's water program offices are developing plans to implement PBMS. EPA
anticipates that the final rule to implement PBMS in water programs
will be published in 1999 based on the March 28, 1997
[[Page 30420]]
proposed rule. Consistent with Agency PBMS implementation plans, EPA
Method 1631 incorporates QA and QC acceptance criteria to serve as a
basis for assessment of method performance. When PBMS is in place, EPA
Method 1631 would serve as a reference method for demonstrating
equivalency when modifications are made.
EPA Method 1631 also employs a performance-based approach to the
sample preparation and trapping systems. Analysts are allowed to modify
the sample preparation and trapping aspects of the method provided all
the specified performance criteria are demonstrated and documented. The
method also allows the use of alternate reagents and hardware provided
that the analyst demonstrates equivalent or superior performance and
meets all QC acceptance criteria.
Demonstrating equivalency involves two sets of tests, one set with
reference standards and the other with the sample matrix. The
equivalency procedures include performance of the IPR test using
reference standards to demonstrate that the results produced with the
modified procedure would meet or exceed the QC acceptance criteria in
EPA Method 1631. In addition, if the detection limit would be affected
by a modification, performance of an MDL study is required to
demonstrate that the modified procedure could achieve an MDL less than
or equal to the MDL in EPA Method 1631 or, for those instances in which
the regulatory compliance limit is greater than the ML in the method,
one-third the regulatory compliance limit. For a discussion of these
levels, see EPA Method 1631 or the March 28, 1997 proposed rule at 62
FR 14976.
IV. Changes to EPA Method 1631 Since Proposal
The Agency has revised EPA Method 1631, Revision A based on
comments received on the proposal (63 FR 28868, May 26, 1998) and the
NODA (64 FR 10596; March 5, 1999). The significant modifications in EPA
Method 1631, Revision B are the change of the sample holding time (from
6 months to 28 days), the change of the MS/MSD performance criteria
(for recovery from 75-125 percent to 71-125 percent recovery), and a
change in reporting requirements.
A. Holding Time Change
EPA proposed the 6 month holding time for preserved aqueous samples
to be analyzed by EPA Method 1631. Because the 6 month holding time was
not evaluated in the method validation study supporting the proposal,
EPA requested data that would support the 6 month holding time. Data
were not available. Therefore, in the version of EPA Method 1631 being
approved for use today, EPA has set the holding time to 28 days, the
prescribed holding time listed in Table II at 40 CFR part 136.
B. Performance Criteria Change
The MS/MSD recovery limits in the proposed version of EPA Method
1631 were 75-125 percent. The interlaboratory method validation study
produced MS/MSD limits of 71-119 percent. In response to comments on
the proposal, EPA acknowledges that the lower limit produced in the
interlaboratory study is more appropriate and has changed this limit to
71 percent in the version of EPA Method 1631 approved for use today.
C. Reporting Requirements Change
1. Reporting of Data That Failed To Meet QC Acceptance Criteria
In order to clarify the Agency's intent regarding data that do not
meet the method QC acceptance criteria or that indicate the analytical
system is not in control, EPA has adopted suggestions from commenters
that these data should not be reported or otherwise used for permitting
or regulatory compliance purposes. This modification addresses concerns
that regulated entities could be adversely affected by data not meeting
performance criteria, for example, via compliance monitoring. EPA also
has added a statement to section 13.2 of the method that any decision
not to report data from an analytical system that is out of control
does not provide relief from a permit's underlying requirement to
submit timely reports.
2. Reporting of Blank Results
In today's rule, EPA has expanded reporting of blank results to
include reagent blanks and field blanks so that a regulatory authority
may consider field blank contamination in any compliance determination.
To facilitate assessment of the presence and extent of contamination,
the Agency has revised EPA Method 1631 to require reporting of the
mercury concentration in field blanks as well as in reagent blanks.
Today's rule, however, does not require blank subtraction. Regulatory
authorities or other data users may subtract the concentration of
mercury in field blanks or reagent blanks if subtraction is warranted
on a case-by-case basis. Today's rule does nothing, however, to
preclude the reporting of blank-subtracted results in addition to the
separate reporting of results from samples and from blanks.
3. Reporting Laboratory-Specific MDLS and MLS
EPA has removed the option for laboratories to calculate their own
lower MDLs and MLs in the version of EPA Method 1631 being approved for
use today. EPA believes this will avoid confusion and preclude lower
MDLs and MLs from being used for NPDES permitting or regulatory
compliance determinations.
D. Other Changes and Improvements
1. Changes To Method Implementation
Minor technical improvements were made to EPA Method 1631 to
clarify method implementation. Changes and improvements include:
Revision to sections 7.9, 7.10 and 10.1.1.2 to include two
working standards (0.10 ng/mL and 10.0 ng/mL) in order to correct
inaccurate standard concentration levels.
Language changes in sections 4.4.1 and 9.3.4.1 to address
iodide interferences that have been identified and assessed since
proposal. This modification required the addition of a reference
supporting the handling of iodide interferences. The additional
reference has been added to EPA Method 1631 as Reference 10.
Revisions to sections 9.4.2.2 and 11.1.1.2 to include a
requirement that a reagent blank include the same amount of reagent as
the sample being analyzed.
Revisions to section 11.1.1.2 to include recommendations
to assure that complete oxidation has occurred.
Where appropriate, the word ``analyst'' was changed to
``laboratory'' to acknowledge that various sections of EPA Method 1631
may be performed by different analysts in the same laboratory.
2. Corrections To Method
Minor changes were made to correct typographical and information
errors. Nearly all of the corrections are the result of comments and
include:
In section 9.1.2.1, ``less than'' was changed to ``less
than or equal to.'' A method modification must achieve an MDL ``less
than or equal to'' one-third the compliance limit or the MDL.
In section 12.4.1, > 0.2 ng/L has been corrected to < 0.2="" ng/l.=""> In Table 2, (s) has been corrected to RSD for precision.
In Table 1, the lowest ambient water quality criterion has
been corrected from 1.8 ng/L (human health criterion) to 1.3 ng/L
(wildlife criterion).
[[Page 30421]]
The lowest WQC for the Great Lakes is 1.3 ng/L, the criterion for
wildlife protection (see Table 4 to 40 CFR part 132).
In section 4.2, Reference 5 has been changed to Reference
9, which is a paper discussing contamination of samples by dental work
containing mercury amalgam fittings.
References 10 through 20 in the proposed version of EPA
Method 1631 have been changed to References 11 through 21 in the final
version to include the addition of a new Reference 10 addressing
handling of samples containing iodide interferences.
3. Clarifying Statements
As a result of comments:
In section 4.3.8.5, a statement was added to clarify that
reagents can be a source of contamination.
Sections 4.3.8.2 and 5.3 were modified to clarify the
meaning of ``high'' concentration of mercury and to caution that
samples containing mercury concentrations greater than 100 ng/L should
be diluted prior to bringing them into the clean room or laboratory
dedicated to processing trace metals samples and that samples
containing
g/L concentrations of mercury should be treated as hazardous.
4. Additions To Health and Safety Monitoring and Waste Management
Today's version of EPA Method 1631 includes two additions made to
address and clarify health and safety monitoring and waste management.
In section 5.2, EPA added a recommendation that personal
hygiene monitoring should be performed using Occupational Safety and
Health Administration (OSHA) or National Institute of Occupational
Safety and Health (NIOSH) approved personal hygiene monitoring methods.
In section 15.1, a reference was added to address waste
management techniques: Environmental Management Guide for Small
Laboratories (EPA 233-B-98-001). None of the changes or improvements to
the Method discussed above warrant re-proposal because these changes
merely respond to public comment to clarify, correct minor errors, or
otherwise improve the Method. None of these changes impair method
performance or reliability.
V. Public Participation and Response to Comments
The Agency proposed EPA Method 1631 (``Method 1631''; or ``the
Method'') on May 26, 1998 (63 FR 28867). The comment period closed on
July 27, 1998. In addition to providing notice of the Method, the
proposal also solicited information and data that might be relevant to
the Agency's decisionmaking. EPA both received information and data and
developed additional data confirming the proposal. EPA issued a notice
of data availability (NODA) and request for comment on these data (64
FR 10596; March 5, 1999). The NODA comment period closed on April 5,
1999. During the NODA comment period, EPA again solicited additional
data and information on EPA Method 1631.
EPA received more than 500 detailed comments from approximately 30
commenters. Comments ranged from praise and support for EPA Method 1631
to concern about the possible setting of compliance limits at the MDL
or ML and suggestions for improving the technical details of the
method. EPA appreciates the constructive comments and suggestions and
believes that today's version of EPA Method 1631 will provide reliable
data for compliance monitoring. A summary of the significant comments
is presented below, followed by EPA's response. See the Docket for a
complete summary of the detailed comments and more extensive responses.
A significant report received during the comment period was
provided by the Department of Environmental Protection (DEP) in the
State of Maine titled: ``Mercury in Wastewater: Discharges to the
Waters of the State'' (the ``Maine Report''). The Maine Report gives
details and results of analysis of 104 ambient water samples and more
than 150 wastewater samples (primarily effluents) using the proposed
version of EPA Method 1631. The Maine Report is exemplary in that it
allowed Maine's DEP to assess the presence and concentration of mercury
Statewide, and will allow the State of Maine to focus its resources on
problem areas within the State. The Maine Report is also significant
because it provided a comprehensive ``real world'' assessment of the
measurement capability of EPA Method 1631. The Maine Report
demonstrates that EPA Method 1631 can be applied successfully to
determination of mercury in a wide variety of effluents and ambient
waters. Of particular interest is that, of 104 ambient water samples
tested, no sample contained mercury at a concentration greater than 7
ng/L. Of the more than 100 effluent samples tested, only one contained
mercury above the 200 ng/L level that previously approved methods for
mercury could have measured. EPA has placed a copy of the Maine Report
in the Docket for today's final rule. EPA recommends that all persons
interested in making reliable mercury measurements in ambient water and
discharges read the Maine Report. EPA publicly thanks the State of
Maine and particularly the Department of Environmental Protection for
its contribution. Comments and responses are organized and presented by
subject area.
1. Support for EPA Method 1631
Comment: Commenters strongly support the need to reliably measure
mercury levels in ambient waters. The method is technically sound and
the chemistry behind the method is superb. The Agency should move
aggressively to implement this method. Permitting authorities and
others should take the necessary steps to see its adoption and use. EPA
Method 1631 will: (1) Allow gathering of the type of information
crucial to understanding mercury in the environment; (2) allow better
analytical information on the levels of mercury in various waters to
help decide if and where source reduction efforts would be most
effective; (3) allow facilities to better assess actual discharges and
progress in reducing mercury in effluents; (4) allow permitting
authorities to establish appropriate limits based on ecological or
human health endpoints, rather than being limited by the less-sensitive
analytical techniques routinely utilized; (5) allow agencies to better
monitor response of ambient waters to mercury reduction initiatives;
(6) be useful for situations in which an authority or facility believes
that results obtained with currently approved methods do not reflect
actual levels because of contamination during sample collection,
handling, and analysis; and (7) allow the State of Wisconsin to meet
the recommendations of the ``Wisconsin Strategy for Regulating Mercury
in Wastewater.'' The Wisconsin strategy recommends development of
better analytical capability to adequately quantify the level of
mercury at effluent levels that have the potential to cause
environmental degradation.
Response: EPA appreciates the support and, in particular, the
recognition that a method for measuring mercury at ambient water
quality criteria levels is overdue, that the method is based on sound
science, and that EPA Method 1631 will protect dischargers from false
reports that mercury is present in an effluent when, in fact,
inadequate sampling and laboratory procedures accounted for the mercury
measured in the sample.
[[Page 30422]]
2. Practicality and Cost
Impractical and Costly
Comment: The required use of EPA Method 1631 would impose an
economic burden on industry, would force purchase of expensive new
equipment, and would require a significant increase in operating
expenses. The cost of a Class 100 clean room is $50,000-$200,000. The
analytical equipment will cost $10,000-$45,000. Fluoropolymer bottles
will cost an estimated $7,200. The bottle cleaning protocol would
require dedicated laboratory space and staff. Additional cost will be
incurred for training.
Response: Not every facility will need to create a clean room and
bottle cleaning capacity, because commercial laboratories are available
and can supply clean bottles. In a study conducted by Ford Motor
Company, the cost per sample analysis was in the range of $50-$80.
EPA's experience is that costs per sample typically range between $50
to $110. EPA does not believe that this cost is unreasonable. If a
facility desires to establish a laboratory for analysis using EPA
Method 1631, however, EPA has provided guidance for establishment of
``clean spaces'' that will minimize costs in establishing a ``clean''
facility (see References 6 and 7 in Method 1631).
Lack of Laboratory Capability
Comment: Relatively few laboratories nationwide currently have the
expertise and infrastructure to conduct analysis using this Method.
Response: Not every laboratory will need to establish the
capability to conduct EPA Method 1631. Analytical costs are likely to
decrease as demand for and use of the Method increases. Today more than
ever, laboratories and other businesses respond rapidly to new business
opportunities. Therefore, the Agency anticipates that capacity will
develop rapidly as the demand increases for analyses by EPA Method
1631.
Sampling With EPA Method 1669
Comment: Required use of the radical field sampling procedures in
EPA Sampling Method 1669 to support EPA Method 1631 would significantly
increase cost and staff necessary to sample for mercury analysis alone.
One additional sampling person (for clean hands/dirty hands) and
ultraclean sampling protocols will cost approximately $34,000.
Response: Once sampling personnel become familiar with the ``clean
hands/dirty hands'' technique and procedures recommended in EPA Methods
1631 and 1669, sampling for mercury can proceed quickly and
efficiently. EPA does not believe that full-time sampling personnel
will be needed. EPA anticipates that samples may need to be collected
monthly, quarterly, or yearly, depending on the facility and whether
mercury is measured at levels of concern. Therefore, the actual
incremental cost for collection of samples using the techniques
suggested in EPA Method 1669 will be small.
3. EPA Method 1631 Represents a Significant Regulatory Action
Significant Regulatory Action Under Executive Order 12866
Comment: The proposed rule is a ``Significant Regulatory Action''
under Executive Order 12866 (58 FR 51735, Oct. 4, 1993).
Response: It has been determined that this rule is a significant
regulatory action and was, therefore, reviewed by the Office of
Management and Budget (OMB).
Cost Increase Stated in Great Lakes Guidance
Comment: EPA acknowledged in Table 5-13 of Assessment of Compliance
Costs Resulting from Implementation of the Final Great Lakes Water
Quality Guidance (the ``Assessment Document'') that the annual cost
could increase by $569.8 million if future MDLs became 10 times lower
and could increase by $882.5 million if future MDLs became 100 times
lower. EPA Method 1631 lists an MDL 1000 times lower. This rule should
be subject to OMB review.
Response: The estimated compliance cost increases in the Assessment
Document referred to future MDLs for all toxic pollutants (not just
mercury) assuming MDLs might be used as compliance limits (and the MDL
used for compliance evaluation). The Assessment Document states that
the minimum level (ML), not the MDL, should be used for compliance
evaluation when the WQBEL is below the detection or quantitation limit
of the most sensitive analytical method. Today's rule implicates
neither of these limits (MDL nor ML) because EPA Method 1631 allows
reliable measurements below the lowest ambient water quality criterion
(1.3 ng/L) in the final Great Lakes Water Quality Guidance. The
Assessment Document presumed that costs would increase if dischargers
were required to meet discharge requirements at the lower MDLs, not
that it would cost these amounts if EPA allowed use of another method
for the measurement of mercury. In any event, EPA evaluated compliance
costs in the Great Lakes rulemaking because it would result in
establishment of standards of compliance. Today's rule does not set
standards of compliance, only standards of measurement and analysis.
This rule is considered a significant regulatory action and was,
therefore, reviewed by OMB.
Unfunded Mandates Reform Act
Comment: The Unfunded Mandates Reform Act (UMRA; 25 U.S.C. 1531,
Subchapter II), requires assessment of the effects of regulatory
actions on the private sector and preparation of a statement containing
qualitative/quantitative cost-benefit analysis if costs are expected to
exceed $100 million. EPA should perform the cost and benefit
assessments because existing permits require the use of the most
sensitive test procedure.
Response: EPA acknowledges that some permits may require the
permittee to use the most sensitive test procedure available at the
time of permit issuance, for example, when the limit is below detection
of approved methods. Today's rulemaking does not automatically change
permits issued prior to today. The only costs associated with today's
rule are analytical costs, not compliance costs. Today's rule is not
subject to the requirements of sections 202 and 205 of UMRA because it
does not contain a Federal mandate that could result in expenditures of
$100 million or more for State, local, and tribal governments, in the
aggregate, or the private sector in any one year. EPA estimates the
incremental analytical costs associated with the use of EPA Method 1631
instead of another approved method for mercury to be less than $2.6
million per year. EPA believes that this rule does not impose any
regulatory requirements that might significantly or uniquely affect
small governments because the rule approves an additional test
procedure for the measurement of mercury that might be regulated by
some other action (e.g., a permit that implements a State-adopted water
quality standard).
Regulatory Flexibility Analysis
Comment: The Regulatory Flexibility Act (RFA) requires description
of impact of regulatory actions on small entities. EPA is incorrect in
stating that the rule will not have a significant economic impact on
small facilities. Commenters request that the rule be subject to OMB
review and a regulatory flexibility analysis.
Response: In section VI.C. of the proposal, pursuant to section
605(b) of
[[Page 30423]]
the Regulatory Flexibility Act, 5 U.S.C. 605(b), the Administrator
certified that this rule will not have a significant economic impact on
a substantial number of small entities. This regulation approves an
additional test procedure (analytical method) for the measurement of
mercury which may be required in the implementation of the CWA (e.g.,
issuance of permits and/or establishment of WQS). EPA Method 1631 is
not a de facto replacement for EPA Method 245.1 or any of the other
existing EPA-approved methods. EPA anticipates that permit writers will
only require the use of EPA Method 1631 if there is a need to assess
effluents or ambient water at the low levels EPA Method 1631 can
measure or after a determination that a discharge causes, has a
reasonable potential to cause, or contribute to an excursion from a
water quality criterion for mercury. EPA further anticipates that the
incremental analytical costs that may potentially be incurred by any
small entity with low mercury limits will be at most $600 per year,
assuming monthly monitoring.
4. Regulatory implications
Support for Use in Permitting
Comment: EPA should require immediate implementation of the new
method and should require States to begin requiring it for NPDES
compliance as soon as possible.
Response: Today's rule authorizes use of EPA Method 1631 but does
not require its use for compliance monitoring or any other uses. The
Agency developed EPA Method 1631 to enable reliable measurement of
water samples at the levels established in water quality criteria.
Consequently, EPA expects that when the measurement sensitivity of EPA
Method 1631 is necessary to assess and implement water quality controls
(including compliance monitoring), EPA Method 1631 will be used. If and
when other methods for measuring mercury at these low levels are
promulgated in 40 CFR part 136 or are approved under the procedures at
40 CFR 136.4 and 136.5, the permitting authority would have discretion
to determine which method is most appropriate under the circumstances.
States that are authorized to administer the NPDES program must
require use of 40 CFR part 136 methods. EPA recognizes that States may
need to follow State procedures to adopt changes to 40 CFR part 136
before they can require use of a newly promulgated method and allows
States a reasonable time to accomplish this. See 40 CFR 123.62(e). EPA
regulations do not require that permits be reopened to include a new
analytical method. Instead, the permitting authority may have the
opportunity to reopen the permit or to wait until the permit is
reissued to include a new or more sensitive analytical method. See 40
CFR 122.62(a)(2).
Best Available Sensitivity
Comment: EPA failed to acknowledge that many existing permits
require the permittee to use the test method with the lowest detection
level.
Response: EPA recommends that EPA Method 1631 be used only for
situations in which mercury may be known or thought to be the cause of
an environmental or human health problem, or for investigations
directed at determining whether a problem exists, in the same way that
EPA recommends that other test methods be used. EPA Method 1631 is
being made available for use when it is necessary to measure mercury
concentrations at low levels. As previously explained, existing permit
requirements to use the most sensitive method available may only
incorporate the most sensitive method at the time the requirement was
imposed, not methods adopted in the future.
Reporting vs. Use of Data
Comment: EPA Method 1631 states that results need not be reported
for regulatory compliance purposes if the results do not satisfy QC
acceptance criteria. The Inter-Industry Analytical Group (IIAG)
suggests that EPA change the phrase to read: ``. . . may not be
reported or otherwise used for permitting or regulatory compliance
purposes.'' IIAG also requests that EPA clarify that results from tests
performed with an analytical system that is not in control also should
not be reported or otherwise used for permitting or regulatory
compliance purposes.
Response: EPA has adopted IIAG's suggested wording, and changed
relevant text in EPA Method 1631 accordingly. The wording changes
clarify the Agency's intent that data that fail to meet the Method's QC
acceptance criteria are not reliable measurements of mercury.
Iodide Interference
Comment: The Inter-Industry Analytical Group (IIAG) comments that
EPA fails to give adequate consideration to interferences and cites, as
an example, an iodide interference problem encountered by GPU Nuclear
Co. (GPU) using EPA Method 245.1. GPU attributes this interference to
formation of a stable complex of iodide and mercury that prevents
reduction of mercury to its elemental form with the stannous chloride
(SnCl2) reductant. (SnCl2 also is used in EPA
Method 1631). GPU has overcome the problem by addition of a small
amount of sodium tetrahydroborate to aid in reduction of mercury.
Response: EPA did not claim that EPA Method 245.1 was free from
test interference. The claim was made concerning EPA Method 1631. EPA
Method 1631 uses different chemistry than EPA Method 245.1. In EPA
Method 1631, mercury is oxidized to Hg(II) with bromine monochloride,
pre-reduced with ammonium hydroxide hydrochloride
(NH2OHHCl) to destroy free halogens, then reduced
with SnCl2. The NH2OHHCl likely plays
the same role as the sodium tetrahydroborate in GPU's procedure. EPA
has now received a report that high concentrations of iodide (>40 mg/L)
can interfere in the determination of mercury using EPA Method 1631.
These high concentrations can occur in in-process streams and
influents, but normally would not be encountered in treated effluents.
To allow for the possibility that high concentrations of iodide,
however, and the possibility that other substances could interfere in
the determination of mercury using EPA Method 1631, today's version of
EPA Method 1631 acknowledges that test interference remain a slight
possibility.
Variability and Regulatory Decisions
Comment: The Inter-Industry Analytical Group (IIAG) comments that
EPA's QC acceptance criteria and other variability must be taken into
account in regulatory decisions. IIAG cites the QC acceptance criteria
for the matrix spike and matrix spike duplicate (MS/MSD) in EPA Method
1631 and questions EPA's rationale for determining that such a wide
range of performance is acceptable, given the harsh regulatory
consequences associated with excursion of permit limitations. IIAG
states that EPA must explain why such variability is acceptable and how
regulators are required to account for that variability in their
permitting and/or compliance decisions.
Response: EPA disagrees that QC acceptance criteria are ``wide.''
These criteria are consistent with, or narrower than, other methods for
measuring pollutants at these levels (see for example the QC acceptance
criteria for EPA Methods 608 and 1613 at 40 CFR part 136, appendix A).
The QC acceptance criteria recognize the variability expected to occur
among laboratories. The EPA developed the criteria from multiple,
single-laboratory
[[Page 30424]]
data and verified the data in the interlaboratory study. The Agency
used the laboratory data to develop the QC acceptance criteria in
today's rule.
Regarding accounting for variability in permitting and compliance
decisions, EPA's technology-based rules do account for analytical
variability because measurement variability is a component of the
overall variability encountered to develop the rule (including field
measurement). Therefore, no additional allowance for analytical
variability is appropriate. For water quality uses, accommodation for
the effect of analytical variability is less routinized. In the
Technical Support Document (TSD) for Water Quality-based Toxics Control
(EPA/505/2-90-001), EPA noted that accounting for analytical
variability in establishing permitting requirements can result on the
one hand, in failure to be adequately protective of the wasteload
allocation or, on the other hand, to be overly conservative. Therefore,
EPA recommended against any additional allowance for analytical
variability. However, EPA currently is developing guidance on
accounting for analytical variability in permitting in the context of
the whole effluent toxicity program. When finalized, that guidance may
provide the basis for revising the position taken in the TSD with
respect to accounting for analytical variability in general.
5. Retention of Approved Methods and Approval of Additional Methods
Support as Additional Method, With Qualification
Comment: Commenters support approval of EPA Method 1631 if it is an
addition to the list of approved methods and not a replacement for
existing methods, especially if a laboratory can demonstrate that it
can achieve low ng/L detection limits (including needed sensitivity)
with one of the presently approved methods.
Response: Today's rule approves EPA Method 1631 as an additional
method that can be used when measurement of mercury at water quality
criteria levels is needed. EPA doubts that a laboratory can achieve the
low levels (including needed sensitivity) with one of the presently
approved methods. Typically, the MDL of a method should be an order of
magnitude (factor of 10) below the level desired for measurement (e.g.,
a regulatory compliance limit, or any water quality criterion) so that
contamination can be detected and the effects of contamination
evaluated. If the detection limit is at or near the level desired for
measurement, it would be difficult to determine if the presence of the
substance is real or is attributable to contamination. The capabilities
of EPA Method 1631 enable such an evaluation.
Support Continued Use of Approved Methods
Comment: EPA should continue to allow the use of other approved
methods. Withdrawal of existing methods (EPA 245.1, 245.5, Standard
Method 3112B, ASTM D3223-91, USGS I-3462-85, and AOAC-International
977.2) would be disastrous. There would be serious adverse economic
ramifications if EPA Methods 245.1 and 245.2 are withdrawn. EPA Method
1631 should not be imposed on the private sector as the sole method.
The option of using less sensitive methods should remain where EPA
Method 1631 sensitivity is not needed.
Response: Based on comments received and the points made in those
comments, today's rule allows continued use of the presently approved
methods for determination of mercury when those methods achieve the
desired measurement objective.
Performance-Based Measurement System
Comment: The performance-based measurement system (PBMS) as applied
in proposal allows for sample preparation and trapping modifications,
but does not allow for use of atomic absorption. EPA should accept
application of PBMS for a different absorbance technique when it can
achieve needed sensitivity.
Response: EPA proposed to implement PBMS in its water measurement
programs (62 FR 14975, March 28, 1997) but has not yet promulgated a
final PBMS rule. EPA anticipates that the final rule will allow use of
alternate determinative techniques such as atomic absorption. Until a
final rule is promulgated, however, methods approved at 40 CFR part 136
must be used according to their terms. Approval of the use of alternate
procedures, such as alternate determinative techniques, can be
requested through the alternate test procedure provisions described at
40 CFR 136.4 and 136.5.
6. Application to Wastewater Matrices
Inapplicable to Effluent
Comment: EPA Method 1631 is not applicable to the determination of
mercury in effluents. The Method should contain a statement that it is
not intended for the determination of concentrations normally found in
industrial discharges. Language in an earlier version of EPA Method
1631 (January 1996) stated that ``this method is not intended for
determination of metals at concentrations normally found in treated and
untreated discharges from industrial facilities.''
Response: When the Agency first began development of EPA Method
1631, the method description contained the statement that it was
applicable to ambient monitoring but that it was not intended for
application to industrial discharges. Since then, however, in studies
of POTWs along the Great Lakes, in the interlaboratory validation
study, and in other recent studies (Results of Method 1631 Application
to Effluent Matrices (March 1999) and Application of Method 1631 to
Industrial and Municipal Effluents (December 1998)), EPA has found that
mercury could be reliably measured at low levels in municipal and
industrial discharges. For this reason, and because some States
requested EPA support to develop the method for measurement of
municipal and industrial discharges, the Agency expanded EPA Method
1631 to cover wastewaters. The statement regarding restricted use of
EPA Method 1631 was deleted from the January 1996 version.
Testing One Effluent Is Inadequate
Comment: Testing one effluent at one level by a few laboratories is
not an appropriate inter-laboratory study for general NPDES
application.
Response: The Agency validated EPA Method 1631 on one filtered and
one unfiltered wastewater matrix in the interlaboratory validation
study. Subsequently the Agency gathered additional effluent data in
response to comments regarding the method's applicability to
wastewaters generally. EPA made these data available in a notice of
data availability on March 5, 1999 (64 FR 10596). These data
demonstrate that EPA Method 1631 is applicable for measurement of
municipal and industrial effluents.
7. Detection and Quantitation
MDL Is Flawed
Comment: Several commenters state that Agency estimates of
detection and quantitation in EPA Method 1631 are flawed. The estimates
cannot be achieved in real world use. The estimates are scientifically
unsound. The estimates are neither realistic nor reproducible. The
estimates use an inappropriate multiplication factor. They overestimate
the certainty associated with measurements. The estimates are not
representative of expected performance by qualified laboratories. They
are not a valid statistical basis for predicting laboratory
[[Page 30425]]
performance. The estimates were based on spikes into reagent water
instead of wastewaters. The estimates do not consider effluent
characteristics. The estimates are based on a protocol that has never
been subjected to peer review and public comment. The estimates do not
reflect the performance capability of laboratories that will be
performing compliance monitoring.
Response: EPA disagrees that the MDLs and MLs in EPA Method 1631
were developed inappropriately. EPA Method 1631 employs the method
detection limit (MDL) (see 40 CFR part 136, appendix B). The MDL is
defined as the minimum concentration of a substance that can be
measured and reported with 99% confidence that the analyte
concentration is greater than zero and is determined from analysis of a
sample in a given matrix containing the analyte. The MDL procedure is
not designed to control ``false positives'' or ``false negatives,''
allow for repetitive testing, or predict laboratory performance.
However, since the variability of the blank is expected to be
approximately equal to the variability at the MDL, measurement results
greater than the MDL are unlikely to be obtained when measuring samples
that do not contain the substance of interest. In effect, the MDL can
be used to control the rate of ``false positives.'' Reagent water is
the matrix used for determining the MDL performance measure of a method
because (1) reagent water is available to all laboratories, (2) reagent
water allows determination of the lowest concentration of a substance
that can be detected absent matrix interferences, and (3) there is no
matrix that represents all wastewater matrices. Application of the MDL
procedure to particular methods has been subject to peer review and
public comment with every MDL that EPA publishes in nearly every
chemical-specific method proposed in the Federal Register since 1984.
The MDL procedure has widespread acceptance and use throughout the
analytical community. No other detection or quantitation limit
procedure or concept has achieved this level of acceptance and use.
EPA Method 1631 incorporates the concept of a minimum level of
quantitation (ML), which is the lowest level at which an analytical
system is expected to give a recognizable signal and acceptable
calibration point. In 1994, EPA revised its use of the ML concept to 10
times the standard deviation associated with the MDL in order to be
more consistent with the limit of quantitation (LOQ) of the American
Chemical Society (ACS). The LOQ is based on a standard deviation of
replicate measurements on a blank, which is expected to be
approximately equal to the standard deviation of replicate measurements
at the MDL. Therefore, EPA expects the ML to be approximately equal to
the LOQ. Because the MDL is established at 3.14 times the standard
deviation associated with the MDL and the ML is 10 time the standard
deviation associated with the MDL, the multiplier between the MDL and
ML is 3.18. EPA believes that this multiplier is consistent with other
multipliers selected for the purpose of quantitation and that this
multiplier is therefore appropriate. Readers are referred to the
response to comments document in the Docket for today's rulemaking for
a more detailed response.
EPA plans to continue to examine the issues of detection and
quantitation. The Agency initiated a study recently to examine the
effects of error from various analytical systems on detection and
quantitation, and plans to involve the public in the application of the
data being gathered to develop an improved approach, if such an
approach is found to exist.
Use of the MDL/ML Concepts Violate Administrative Procedure Act
Comment: Commenters opposed EPA's proposed detection and
quantitation levels because EPA did not provide the opportunity for
review and comment on the basis for the proposed decisions. EPA's
proposal neither describes the origin of the MDL nor explains why the
Agency believes that it is an acceptable basis for developing detection
levels for use in compliance determinations.
Response: The MDL concept origin is an article published in the
peer-reviewed scientific literature in 1981 (Environmental Science and
Technology 15 1426-1435). The MDL procedure has been used in EPA's
various environmental programs since it was published at 40 CFR Part
136, Appendix B in 1984. The MDL procedure is accepted and used by
nearly all organizations making environmental measurements. Recently,
EPA has undertaken data gathering that should allow re-examination of
detection and quantitation limits. When this study is complete, EPA
will decide if the MDL and ML continue to be appropriate or if other
concepts are appropriate for EPA's scientific and regulatory purposes.
EPA has involved, and will continue to involve, stakeholders in this
process and in EPA's final decision. Until other detection and
quantitation limit concepts are shown to be more appropriate, EPA will
continue to use the MDL and ML for the reasons stated at the beginning
of this response, in other responses, and in other rules.
MDL Violates A 1985 Judicial Settlement
Comment: A commenter noted that, in a judicial settlement in 1985,
EPA agreed that the MDL procedure published at 40 CFR part 136,
appendix B, was intended to apply exclusively to the subset of the test
methods that the Agency published at 40 CFR part 136, appendix A, in
1984. Thus, the commenter argues that, if EPA uses the MDL procedure
for the purpose of deriving a detection level for EPA Method 1631, the
Agency must provide the public an opportunity to review and comment on
that decision. As justification for use of the MDL, EPA gave the
reasons that (1) laboratories that participated in the EPA Method 1631
study were able to calculate an MDL at least as low as that achieved in
an earlier study, and (2) the MDL is well below the lowest water
quality criterion (WQC) in the National Toxics Rule and listed in the
final water quality guidance for the Great Lakes System. The commenter
argues that these reasons may be desirable but that they are irrelevant
for determining an appropriate detection level. The commenter argues
that EPA must first confirm that good laboratories can achieve that
level.
Response: The commenter is correct that, in 1985, EPA agreed in a
settlement that the MDL procedure at 40 CFR part 136, appendix B, was
applicable to the 40 CFR part 136, appendix A methods only. The
settlement, however, did not restrict future application of the MDL
procedure, nor did it restrict any person's right to challenge the
Agency's reliance on the MDL procedure in any future rulemaking. EPA
provided the opportunity for comment on use of the MDL in EPA Method
1631. EPA believes that the interlaboratory validation study of EPA
Method 1631 confirms that good laboratories can achieve the detection
and quantitation levels that EPA established for EPA Method 1631.
Effluent Study Offers No Support for the MDL Performance Measure in EPA
Method 1631
Comment: If the intent of EPA's effluent study was to determine
whether MDL calculations are influenced by the sample matrix, EPA
should have used a matrix more representative of real world samples
rather than the City of Eugene's POTW effluent. The mercury level in
the City's effluent was lower than in any
[[Page 30426]]
of the other effluents used in EPA's study.
Response: Step 3(b) of the MDL procedure at 40 CFR part 136,
appendix B requires that the measured level of analyte be less than
five times the MDL. The MDL in EPA Method 1631 is 0.2 ng/L. Five times
the MDL is 1.0 ng/L and therefore the concentration of mercury in the
MDL study needed to be in the range of 0.2 to 1.0 ng/L. The measured
level of mercury in the City of Eugene's POTW effluent was 0.56 and
0.72 ng/L, based on data collected prior to the MDL study. Therefore,
the mercury concentration of the City's sample was in the appropriate
range for the MDL study.
8. Clean techniques
Clean Techniques Should Be Required
Comment: The rule should require clean sampling, handling, and
analysis when EPA Method 1631 is used and the Agency should develop a
comprehensive database on the level of contamination that may arise. A
commenter provided a list of sections in EPA Method 1631 that allow
discretion but that the commenter believes must be made mandatory to
assure reliable and reproducible results, for example, if government
inspectors measure the same sample effluents. The commenter argues that
EPA must explain its rationale for deciding that certain clean
techniques are mandatory and to justify its decision that other
techniques are not mandatory and, therefore, can be left to the
discretion of enforcement officials. The only exception to required use
of clean techniques should be that permittees should have complete
discretion as to the use of such techniques because the failure to use
such techniques can only result in mercury results higher than the
level actually present in an effluent.
Response: During the development of EPA Method 1631, the Agency
found some researchers using very extensive measures for clean
sampling, including the wearing of clean room caps, suits, booties, and
shoulder-length gloves in addition to hand-length gloves. On the other
hand, EPA found other researchers wearing shorts, tee shirts, and hand-
length gloves only. Because the Agency sought to maximize the
flexibility of capable personnel, EPA provided the Sampling Guidance
(EPA Method 1669) to indicate measures to prevent and preclude
contamination. The sampling guidance is not mandatory for use with EPA
Method 1631 because some permittees and sampling teams are capable of
reliable sample collection without the measures detailed in the
guidance. The rigor of clean sample collection techniques is determined
by the required measurement objective or regulatory level (i.e., the
lower the desired level, the more critical is the adherence to rigorous
clean sampling protocols). Those elements of clean sampling, handling,
and analysis that the Agency believes are necessary to assure reliable
and reproducible results have been incorporated into EPA Method 1631.
For example, the use of clean gloves by all sampling personnel and the
use of metal-free apparatus are requirements specified in the method.
In addition, the QC requirements in the method are designed to detect
potential contamination that may arise in the field, during transport,
or in the laboratory.
Regarding development of a comprehensive database, the Agency does
not see the need to develop a database on the level of contamination
that may arise. In both EPA Method 1631 and the Sampling Guidance (EPA
Method 1669), EPA is very explicit that contamination is a concern and,
consequently, the Agency provided appropriate measures to minimize
contamination.
EPA includes a number of mandatory steps in a method when it
believes those steps are necessary to provide reliable analytical
results. If EPA were to justify every discretionary aspect of a method
(indicated by the words ``should,'' or ``may,'' and other words
denoting suggestions) for every method or guidance document that the
Agency develops, method and document development would grind to a halt.
Parametric studies of every variable that could possibly influence the
outcome of a method or use of a document would become cost-prohibitive.
The list of discretionary techniques in EPA Method 1631 that the
commenter suggests should be evaluated would require 20 parametric
studies.
Clean Techniques Should Not Be Required
Comment: Clean techniques should not be required. There is no
documentation in the record that clean field blanks and clean samples
can be collected. This casts doubt on the ability of laboratories and
permittees to use this method in day-to-day activities designed to meet
Clean Water Act requirements. Clean techniques are an unnecessary
expense because detection levels this low are not needed for personal
or environmental protection. EPA Method 1631 is able to detect such low
levels that sample collection and analysis must occur in pristine
environments to prevent false positives.
Response: Clean techniques are not required but are recommended for
low level mercury measurements associated with WQ criteria. EPA
cautions, however, that contamination has been identified as a
potential problem in collecting samples for mercury prior to the advent
of clean techniques. Use of these techniques, as detailed in the
sampling guidance (EPA Method 1669) and in the technical literature
(see references 2-9 of EPA Method 1631), has allowed collection of
samples free of contamination at ng/L levels. EPA urges use of clean
techniques, as appropriate, to preclude contamination. As stated
earlier, those elements of clean sampling, handling, and analysis that
the Agency believes are necessary to assure reliable and reproducible
results have been incorporated into EPA Method 1631.
Although EPA agrees that clean techniques should not be (and are
not) required, EPA disagrees with the commenters assertion that the
record contains no documentation that clean field blanks and clean
samples can be collected. The EPA Method 1631 Interlaboratory Study
included the collection of field samples for use in the study, and
results from background and QC analyses demonstrated the ability to
collect clean field blanks and samples. Following proposal of the
method, EPA also collected additional effluent data and made those
data, including QC results, available in the Docket and through a
notice of data availability (64 FR 10596). These data provide further
demonstration that clean field blanks and clean samples can be
collected.
9. Corrections to statements in proposal
Holding Time
Comment: Proposed EPA Method 1631 lists a holding time of 6 months.
EPA used a period of only one month, however, to evaluate the stability
of the samples. Please provide the basis for the large variation in
holding times between EPA Method 1631 (6 months), EPA Method 245.1 (28
days), and draft EPA Method 245.7 (72 hours). EPA must have data to
support the specified maximum holding time and will need to change
holding time in CFR if EPA Method 1631 is approved.
Response: EPA specified the maximum holding time at 6 months in the
proposed version of EPA Method 1631 based on statements by a number of
laboratories involved in development of EPA Method 1631 that samples
could be held for this period. EPA requested data that would support
the 6 month holding time. Data were not forthcoming. Therefore, in
today's
[[Page 30427]]
version of Method 1631, EPA has specified a maximum holding time of 28
days, consistent with Table II at 40 CFR part 136.
Lowest Water Quality Criterion
Comment: The lowest water quality criterion (WQC) for the Great
Lakes Water Quality Guidance is not 1.8 ng/L. It is 1.3 ng/L, the
criterion for wildlife protection (see Table 4 to 40 CFR part 132).
Waters of the United States frequently exceed these levels even where
there is no direct industrial or municipal discharge.
Response: EPA stands corrected. EPA recognizes that waters of the
United States can exceed Great Lakes WQC levels, even where there is no
industrial or municipal discharge. That possibility, however, does not
affect the substance of today's rule.
10. Quality Control
Excessive quality ControL
Comment: The quality control (QC) in EPA Method 1631 is excessive,
unreasonable, far more rigorous than in currently approved methods, and
demonstrates the inappropriateness of this method for general
application.
Response: The QC in EPA Method 1631 is consistent with the other 40
CFR part 136, appendix A methods and consistent with requirements for
other environmental analytical chemistry methods. EPA believes that the
QC requirements are necessary to ensure the reliability of data results
and that these requirements are not onerous.
Insufficient Quality Control
Comment: Without addition of more comprehensive QC for background,
mercury determinations at low ppt levels are subject to unknown and
unacceptable bias and imprecision. Additional validation and
modification to the QA/QC are necessary for the method to realize its
potential of being a rugged method capable of providing reliable
quantification of mercury at sub-ng/L concentrations.
Response: Bubbler blanks, reagent blanks, and method blanks serve
as checks on contamination. The MDL performance capacity of Method 1631
is 0.2 ng/L. This MDL enables detection of contamination at sub-ng/L
concentrations, should such contamination occur. A discharger or
laboratory is not precluded from performing additional QC if it
desires.
Method Performance
Comment: A commenter argues that EPA must assure that the
irreducible performance limitations inherent in all methods will not
act to penalize persons for lawful conduct. EPA cannot provide such
assurances absent adequate performance data, which can only be derived
from properly conducted method validation studies. If EPA determines
that a test method has been adequately validated, EPA must publish
performance characteristics along with the method.
Response: EPA conducted a validation study on EPA Method 1631.
Published method performance characteristics associated with the Method
include: (1) A method detection limit (MDL) and minimum level of
quantitation (ML) in Table 1, (2) quality control (QC) acceptance
criteria in Table 2, and (3) precision and recovery data for six sample
types in Table 3. These data more than adequately support the adequacy
of the Agency's validation of EPA Method 1631.
11. Blanks and Contamination
Reagent Blanks
Comment: Reagent blanks also should be subtracted from sampling
results. Otherwise, inaccurate, high results will be reported.
Response: Section 12.4 in EPA Method 1631 asks for separate
reporting of results for samples and blanks, unless otherwise requested
or required by a regulatory authority or in a permit. The reason for
separate reporting is so that a regulatory authority can assess if
results for samples are attributable to contamination and the extent to
which contamination is affecting the measurement. There is no
prohibition in EPA Method 1631 against reporting blank-subtracted
results, provided, of course that results for blanks and samples are
reported separately.
Bubbler and Reagent Blanks Inadequate
Comment: Bubbler blanks and reagent blanks only demonstrate that
the analytical system is uncontaminated. Analysis of field or equipment
blanks should not be used to demonstrate laboratory capabilities.
Response: EPA agrees that bubbler blanks and reagent blanks are
used to demonstrate that the analytical system is uncontaminated. EPA
disagrees that field blanks or equipment blanks should not be used to
demonstrate laboratory capabilities. The laboratory is responsible for
determining and reporting field contamination and for demonstrating
that equipment blanks are free from contamination. Section 9.4 of EPA
Method 1631 also contains a statement ``it is suggested that additional
blanks be analyzed as necessary to pinpoint sources of contamination
in, and external to, the laboratory.'' Both field and laboratory
contamination sources may affect the analytical results.
Blank Subtraction
Comment: It should be acceptable to subtract field blank results in
addition to reagent and bubbler blanks. EPA must require correction for
reagent blanks.
Response: EPA has revised section 12.4 of the method to ask for
reporting the concentration of mercury in field blanks but has not
required blank subtraction so that a regulatory authority can assess if
results for samples are attributable to contamination and the extent to
which contamination is affecting the measurement. A regulatory
authority or other data user may subtract the concentration of mercury
in field blanks or reagent blanks if it believes this subtraction is
appropriate. Today's rule does not preclude the reporting of blank-
subtracted results provided that results for samples and blanks are
reported separately.
Sample-Specific Reagent Concentrations
Comment: The reagent blank does not address sample-specific
variation in reagent concentrations. Section 11.1.1.2 states that
sewage effluent will require high levels of bromine monochloride
(BrCl). The increased requirement for BrCl for samples high in organic
materials could increase the background contribution if the BrCl
contains trace amounts of mercury. This could lead to a high bias for
mercury in samples that require high levels of BrCl. EPA Method 1631
states that BrCl cannot be purified (section 9.4.2.3).
Response: EPA agrees and has added the requirement that whatever
concentration or amount of reagent that is added to the sample must
also be added to the reagent blank in order to identify the reagent as
a potential source of contamination. Regarding the statement in EPA
Method 1631 that BrCl cannot be purified, EPA believes that this
statement is true. BrCl, however, is made in the laboratory from
several reagents that can be obtained in highly purified form. The
resulting BrCl will then be very pure.
12. Validation Study
Insufficient Validation
Comment: Insufficient method validation has been provided to
justify method use for routine NPDES purposes.
Response: The validation steps performed with EPA Method 1631 are
[[Page 30428]]
the same as EPA has performed with many other methods. The Agency
validated EPA Method 1631 first in multiple single-laboratory studies
and then further validated the method in an interlaboratory study. EPA
followed ASTM Practice D 2777 in the interlaboratory validation study
design. Some members of the ASTM Committee D-19 on water reviewed the
interlaboratory study plan and contributed to the study. In response to
commenters concerned about the application of EPA Method 1631 to NPDES
effluents, EPA gathered data on application of EPA Method 1631 to
effluents and made these data available to commenters for review prior
to today's final rule (64 FR 10596).
Validation Under Routine Conditions
Comment: Validation data results were not obtained under normal,
routine analytical operations. EPA Method 1631 should not be
promulgated until it is validated using commercial laboratories able to
sample and analyze waste streams using ultra-clean techniques. The fact
that EPA Method 1631 has been subjected to the required validation
studies alone does not ensure that it is ready for widespread
application.
Response: Commercial laboratories were included in the
interlaboratory method validation study and all laboratories involved
in the study perform mercury analyses routinely using the techniques in
EPA Method 1631. It is not necessary for commercial laboratories
involved in the analysis of samples for mercury to be able to sample
waste streams, although some do. All laboratories involved in the
interlaboratory study analyze waste streams and all of the laboratories
involved in the study determined their respective detection limits. EPA
believes that the fact that EPA Method 1631 has been subjected to the
required validation ensures that it is ready for widespread
application. Over time, commercial laboratories will develop capacity
to conduct EPA Method 1631 just as they have for other, previously
approved test methods.
Additional Interlaboratory Studies
Comment: EPA's intralaboratory (i.e., within laboratory) studies
reported in the Docket with the NODA failed to evaluate the matrix
issue in a ``real-world'' interlaboratory context. EPA did not assess
interlaboratory precision and bias in studies included with the NODA.
EPA's data are insufficient to characterize precision and bias of
mercury measurements in industrial effluents. Although the study
included analysis of mercury samples by multiple laboratories, none of
the samples was split between laboratories. The studies should have
been designed to determine interlaboratory and multi-matrix precision,
accuracy, and sensitivity of EPA Method 1631.
Response: Assessing interlaboratory precision and bias was not an
objective of the additional studies. EPA assessed interlaboratory
precision in the interlaboratory validation study and published
performance data for the interlaboratory validation study in the report
that was included in the Docket at proposal. In comments on EPA's
proposal of EPA Method 1631 on May 26, 1998 (63 FR 28867), commenters
expressed concern that only one municipal secondary effluent had been
analyzed to determine precision and bias and that no industrial
wastewater samples were analyzed. They argued that it was unreasonable
for EPA to adopt a method with no data on the applicability to a wide
variety of wastewater matrices. In response to those concerns, the
Agency applied EPA Method 1631 to a wide variety of wastewater
matrices, including industrial wastewater samples. EPA gathered data
generated from the analyses of several different types of effluent
samples in order to determine whether the results from that study meet
the quality control (QC) acceptance criteria from the proposed method.
EPA developed the QC acceptance criteria as a means of assuring the
appropriate levels of precision and bias. Re-evaluation of precision
and bias would be unnecessary if the QC acceptance criteria remained
appropriate.
The commenters claim that EPA Method 1631 was validated
inadequately because EPA did not conduct interlaboratory method
validation studies on a wide variety of wastewater matrices containing
naturally occurring mercury levels near the ML of EPA Method 1631. EPA
disagrees. The ASTM guidelines recommend the use of reagent water as a
reference matrix in at least one environmental sample matrix other than
the reference matrix. EPA included a municipal effluent in the
interlaboratory validation study. It would be impractical to use a wide
variety of wastewater matrices with natural concentration near the ML
of EPA Method 1631 because the levels in the sample are unknown prior
to analysis. EPA followed ASTM and AOAC guidelines for the
interlaboratory method validation study conducted prior to proposal.
EPA believes that the Agency has fully addressed commenters' requests
for additional data on the application of EPA Method 1631 to
wastewaters. Commenters that have requested that EPA conduct extensive
interlaboratory studies were involved in, and had the opportunity to
contribute to, EPA's interlaboratory method validation study at the
time it was conducted. These commenters chose not to contribute to a
more extensive study or conduct studies on their own.
EPA reiterates that the main objective in conducting the additional
studies was to demonstrate that effluent samples containing mercury at
or near the ambient water quality criteria levels given in the National
Toxics Rule (40 CFR 131.36) and in the Water Quality Guidance for the
Great Lakes System (40 CFR part 132) could be analyzed with little or
no difficulty. Data included in the Docket with the NODA and data
provided by the State of Maine demonstrate that these measurements can
be made reliably, claims from commenters about interlaboratory
variability, precision, accuracy, and sensitivity notwithstanding.
Insufficient Concentrations
Comment: A commenter argued that EPA failed to validate EPA Method
1631 at a sufficient number of concentrations. The commenter cites a
report prepared by the Electric Power Research Institute (EPRI) in
which consultants to EPRI cite ASTM Practice D 2777-96 as the need to
validate the method using samples spiked at multiple levels.
Response: EPRI and EPA collaborated on the study design for the EPA
Method 1631 interlaboratory validation study. EPA shared data from the
study with EPRI's consultants immediately after these data were
verified and validated. The consultants acknowledge the collaboration
in the attachment to the comment. At the outset of the study, EPA and
EPRI agreed on the limitations of the study, including that there were
insufficient resources to test every matrix at multiple levels. In the
study, EPA validated EPA Method 1631 at multiple levels in reagent
water and in freshwater collected near Port Washington, Wisconsin. To
support today's final rule, EPA has gathered additional data on a
variety of complex effluents using EPA Method 1631 and evaluated them
at the low concentration levels of interest (i.e., low parts per
trillion). These data represent the application of the Method to ``real
world'' effluent samples. The data results demonstrate that Method 1631
can be successfully applied to effluents because all of the matrix
spike and
[[Page 30429]]
matrix spike duplicate (MS/MSD) recoveries were within the QC
acceptance criteria in EPA Method 1631, with the exception of two
samples that were spiked at inappropriate levels.
EPA Did Not Follow Voluntary Consensus Standards Bodies (VCSB)
Procedures
Comment: A commenter claims that EPA failed to use available
standards and practices from VCSBs to design its method validation
study as required by the National Technology Transfer and Advancement
Act (NTTAA) and Office of Management and Budget (OMB) Circular A-119.
The commenter asserts that NTTAA makes no distinction between technical
standards that are themselves scientific tests (i.e., analytical
methods) and standards used in the evaluation of the effectiveness and
reliability (i.e., validation) of those tests. The commenter states
that EPA claims to have complied with NTTAA by developing a new mercury
method that had not yet been developed by a VCSB and that EPA
incorrectly claims to have followed VCSB standards for the design and
conduct of its validation study.
Response: EPA agrees that NTTAA and OMB Circular A-119 require
federal agencies to consider available VCSB standards and practices.
NTTAA requires federal agencies to consult with VCSBs and other
organizations when such participation is in the public interest and is
compatible with agency missions, authorities, priorities, and budget
resources. If compliance with the requirement to use VCSB standards and
practices is inconsistent with applicable law or otherwise impractical,
a federal agency may elect to develop technical standards not developed
or adopted by VCSBs if the head of the agency or department transmits
to OMB an explanation of the reasons for using other standards.
EPA disagrees with the commenter's statement that we failed to use
available standards and practices from VCSBs to design its method
validation study. EPA designed the interlaboratory study with
participation by the Electric Power Research Institute (EPRI) and its
consultants. Individuals in EPRI are members of ASTM Committee D-19 on
water. Committee D-19 developed Practice D 2777. The Agency followed
Practice D 2777 in the study design. Practice D 2777 requires the use
of at least one representative (``reference'') sample matrix which is
the same for all laboratories and recommends the use of at least one
environmental sample matrix. Reagent water is recommended as the
reference sample matrix. In a memorandum attached to the comment, the
only statement suggesting that EPA did not follow Practice D 2777 in
the study design is a statement that Practice D 2777 requires Youden
pairs at a minimum of three concentrations per matrix. EPA included
four concentration pairs in reagent water (and an unspiked pair), four
concentration pairs for freshwater, and one concentration pair each for
marine (one pair filtered and one pair unfiltered) and for a municipal
effluent (one pair filtered and one pair unfiltered). EPA believes that
the design of its validation study follows ASTM Practice 2777-96. EPRI
members were aware of the resource limitations of the study and agreed
that the design's limited number of Youden pairs and blind duplicate
samples would not negate the usefulness of study results.
Performance Data Are Inadequate and Misleading
Comment: A commenter argues that EPA's performance information is
inadequate and misleading because it fails to include regression
equations. Stakeholders need a means to predict how EPA Method 1631
will perform at any particular level within its working range. EPA has
provided regression equations in other methods. EPA inexplicably
departed from this practice. The commenter further argues that EPA's
performance information is inadequate and misleading because the EPA
Method 1631 acceptance criteria are inconsistent with study results.
For example, test data can be used if the initial precision and
recovery falls within the range of 79-121 percent which is broader than
the capability (86-113 percent) demonstrated by the EPA Method 1631
interlaboratory study. EPA must explain the difference in the final
rule, if only to avoid confusion in the interpretation of EPA Method
1631 data.
Response: EPA disagrees that the performance information is
inadequate and misleading. As EPA has stated elsewhere in these
responses, EPA has no knowledge of use of regression equations in the
interpretation of data by dischargers or others. Regression equations
are redundant with QC acceptance criteria. Regression equations can be
used to calculate expected method performance at a given concentration.
The expected performance can, in turn, be used to determine if a
laboratory's performance is equivalent to the performance of
laboratories in the interlaboratory study. On the other hand,
laboratories that practice a method that contains QC acceptance
criteria recognize these criteria as absolute standards of performance
within which the method must operate. Calculating another standard of
performance, as the commenter suggests, would be redundant. Further,
because the QC acceptance criteria are an absolute standard,
laboratories can be held accountable. If they fail to meet this
standard, corrective action would be required followed by reanalysis of
samples after the QC acceptance criteria are met. Standards of
performance derived from regression equations do not ensure this
result.
The difference between the QC acceptance criteria listed in
proposed EPA Method 1631 and in Table 11 of the interlaboratory study
report are attributable to EPA's decision to not tighten the acceptance
criteria from the draft method published in 1995 (EPA 821-R-96-027).
EPA is concerned that any method that is iteratively tested may result
in ever tightening QC acceptance criteria because succeeding data
gathered with the method will likely fall within these criteria. EPA
therefore retained the QC acceptance criteria from the draft method in
the version of EPA Method 1631 proposed. In contrast, EPA has widened
the QC acceptance criteria for the matrix spike and matrix spike
duplicate (MS/MSD) between the proposed version and today's version.
The reason for this widening is that the data gathered in the
interlaboratory study demonstrated that the QC acceptance criteria for
the MS/MSD were too restrictive. Making certain QC acceptance criteria
unreasonably restrictive is onerous upon laboratories, especially new
laboratories beginning to practice a method. Therefore, for EPA Method
1631, the Agency decided not to tighten the QC acceptance criteria for
the IPR and OPR, and loosened the QC acceptance criteria for the MS/
MSD.
Mercury Forms and Species
Comment: Mercury exists in many forms and states. The
interlaboratory validation study failed to consider molecular diversity
of mercury.
Response: EPA Method 1631 determines total mercury. The oxidation
step in EPA Method 1631 oxidizes all commonly occurring forms and
species to Hg(II) which is subsequently reduced to volatile Hg(0) so
that it can be purged from solution and determined.
13. Technical details of EPA Method 1631
UV Oxidation
Comment: EPA must study and validate EPA Method 1631 with UV
[[Page 30430]]
oxidation on a range of industrial effluents and sewage samples,
including ``microbially-rich'' samples. Results of the commenters'
studies suggest that UV photo-oxidation can increase recoveries in some
effluents. The use of UV oxidation makes measurement of mercury method-
defined.
Response: In section 3.1 of EPA Method 1631, the Agency suggests
use of UV oxidation for microbially-rich samples. EPA has added
recommendations for determining complete oxidation. These
recommendations should aid in recovery of mercury from some samples, as
the commenter suggests. Regarding all interferences not being
oxidizable, the commenter provided no example of a non-oxidizable
interference that could occur in wastewaters.
Regarding the use of UV oxidation making mercury a ``method-defined
analyte,'' mercury could become method-defined in EPA Method 1631 only
if it were not recovered reliably from a large number of samples. For
the few number of samples in which incomplete oxidation can occur to
make consideration of mercury as ``method-defined,'' the additional
recommendations should now assure complete oxidation so that mercury
does not need to be considered ``method-defined.'' Total mercury can be
determined reliably.
Safety
Comment: There are safety hazards inherent in the practice of EPA
Method 1631. The preparation of bromine monochloride (BrCl) is more
hazardous than preparation of potassium permanganate (KmnO4). A
significant amount of hot acid is involved in cleaning bottles/
glassware. Laboratory ovens will be destroyed or serve as a source of
contamination as a result of cleaning bottles that need to sit
overnight at 60-70 deg.C with HCl. Further clarification and
explanation is requested on what is required for laboratory personal
hygiene monitoring.
Response: Section 5 of EPA Method 1631 is dedicated to safety
issues, and the sampling guidance (EPA Method 1669) contains additional
information on safety. Section 7.6 of EPA Method 1631 explicitly states
that BrCl must be prepared under a hood because copious quantities of
free halogens are generated. The sampling guidance contains detailed
procedures for bottle cleaning including suggestions for a heated acid
vat in which bottles may be cleaned. Use of metal ovens for heating
acids is not suggested for the reason that the commenter states. EPA
Method 1631 is performance-based, however, and allows laboratories to
modify the cleaning protocols so long as the modified protocols are
capable of yielding uncontaminated equipment blanks.
Regarding personal hygiene monitoring, EPA has added the statement
to EPA Method 1631 to recommend that the personal hygiene monitoring be
performed using Occupational Safety and Health Administration (OSHA) or
National Institute of Occupational Safety and Health (NIOSH) approved
personal hygiene monitoring methods.
14. Miscellaneous
Toxicity Limit
Comment: The fact that EPA has established toxicity limits at
extremely low levels by a means not based on laboratory analyses does
not mean that analytical technology can be developed.
Response: EPA believes that ambient water quality criteria and
health effects-based limits can best be supported by gathering of data
at levels represented by these criteria and limits, the means for
establishing these limits notwithstanding. EPA will continue to strive
to develop the analytical technology that will allow reliable
measurements at these levels.
Dissolved Mercury Only
Comment: EPA should clarify that EPA Method 1631 applies to
dissolved mercury only. If the total digestion is performed, naturally
occurring sediments may contribute significant analyte concentrations
to a result.
Response: Today's rule approves use of EPA Method 1631 for
determination of dissolved and total mercury. If a sample contains
suspended material such as sediment, it is intended that the mercury
attached to or contained in the sediment be included in the
measurement.
Ambient Criterion Based on Methyl Mercury
Comment: The ambient water quality criterion of 12 ng/L for mercury
is based on methyl mercury. EPA incorrectly implied in the proposal
that EPA Method 1631 should be used to show compliance with the methyl
mercury-based 12 ng/L standard, and should remove reference to this
standard if the method is finalized.
Response: The criterion continuous concentration (CCC) of 12 ng/L
is for total recoverable mercury in water (40 CFR 131.36(b)(1)).
Today's rule approves EPA Method 1631 so that reliable measurements of
mercury can be made at this level, the basis for the standard
notwithstanding. Both ``total'' and ``dissolved'' mercury measurements
can be made with this method.
Grab Samples
Comment: The commenter requests that EPA provide a note in 40 CFR
Part 136 that requires only grab samples should be collected when using
EPA Method 1631 because of potential contamination with compositing
sampling procedures.
Response: EPA has not mandated use of grab samples because EPA does
not wish to discourage use of automated compositing equipment or
sampling by other means, although EPA cautions that precluding
contamination using these methods is more difficult than with
collection of grab samples.
Implementation
Comment: A commenter argues that the rulemaking for EPA Method 1631
also must provide an objective and clear description regarding how the
Method is to be implemented in practice.
Response: The meaning of the comment is unclear. If the commenter
means that the details of EPA Method 1631 are inadequate and the
procedures in EPA Method 1631 need to be developed further, EPA
believes that the validation study demonstrates that the procedures in
EPA Method 1631 are more than adequate for implementation of EPA Method
1631 in practice.
If the commenter means that EPA must examine the impact of the
measurements made by the method on the regulatory process, EPA believes
that this activity is outside the scope of method development,
validation, and approval. EPA's regulations for water pollution control
are based on wastewater treatment and water quality considerations as
required by the Clean Water Act. EPA Method 1631 is simply a tool to
measure total mercury in aqueous samples.
Personnel Qualifications
Comment: A commenter argues that EPA should specify the minimum
qualifications for persons performing EPA Method 1631. Section 4.3.2 of
EPA Method 1631 states that it is imperative that the procedures be
carried out by well-trained, experienced personnel.
Response: Section 1.10 states that EPA Method 1631 ``should be used
only by analysts who are experienced in the use of CVAFS techniques and
who are trained thoroughly in the sample handling and instrumental
techniques described in this Method. Each analyst who uses this Method
must demonstrate the ability to generate acceptable results using the
procedure in section 9.2.''
[[Page 30431]]
VI. Regulatory Requirements
A. Executive Order 12866
Under Executive Order 12866 (58 FR 51735, October 4, 1993), the
Agency must determine whether a regulatory action is ``significant''
and therefore subject to OMB review and the requirements of the
Executive Order. The Order defines ``significant regulatory action'' as
one that is likely to result in a rule that may: (1) Have an annual
effect on the economy of $100 million or more or adversely affect in a
material way the economy, a sector of the economy, productivity,
competition, jobs, the environment, public health or safety, or State,
local, or tribal governments or communities; (2) create a serious
inconsistency or otherwise interfere with an action taken or planned by
another agency; (3) materially alter the budgetary impact of
entitlements, grants, user fees, or loan programs or the rights and
obligations of recipients thereof; or (4) raise novel legal or policy
issues arising out of legal mandates, the President's priorities, or
the principles set forth in the Executive Order.''
Pursuant to the terms of Executive Order 12866, it has been
determined that this rule is a ``significant regulatory action.'' As
such, this action was submitted to OMB for review. OMB made no
suggestions or recommendations on this rule.
B. 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 significantly or uniquely may affect small
governments, including tribal governments, it must have developed under
section 203 of 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.
Today's final rule does not contain a federal mandate (under the
regulatory provisions of Title II of the UMRA) for State, local, or
tribal governments or the private sector that may result in
expenditures of $100 million or more in any one year. EPA has
determined that this rule contains no regulatory requirements that
significantly or uniquely might affect small governments. As discussed
below under the Regulatory Flexibility Act, the economic impact on
small entities is anticipated to be small. This rule makes available a
testing procedure which would be used at the discretion of the
permitting authority when compliance with State-adopted water quality
standards necessitates a more sensitive method than those previously
approved. This rule would impose no enforceable duty on any state,
local or tribal governments or the private sector, nor would it
significantly or uniquely affect them. It would not significantly
affect them because any incremental costs incurred are small and it
would not uniquely affect them because it would affect all size
entities based on whether testing for mercury is otherwise required by
a regulatory authority. Further, monitoring for small entities is
generally expected to be less frequent than monitoring for larger
entities. Therefore, today's rule is not subject to the requirements of
sections 202, 203 and 205 of UMRA.
C. Regulatory Flexibility Act
Under the Regulatory Flexibility Act (RFA), 5 U.S.C. 601 et seq.,
as amended by the Small Business Regulatory Enforcement Fairness Act
(SBREFA), EPA generally is required to conduct a regulatory flexibility
analysis describing the impact of the regulatory action on small
entities as part of rulemaking. However, under section 605(b) of the
RFA, if EPA certifies that the rule will not have a significant
economic impact on a substantial number of small entities, EPA is not
required to prepare a regulatory flexibility analysis. Pursuant to
section 605(b) of the Regulatory Flexibility Act, 5 U.S.C. 605(b), the
Administrator certifies that this rule will not have a significant
economic impact on a substantial number of small entities.
This regulation approves a testing procedure for the measurement of
mercury which EPA anticipates will be used by regulatory authorities
when a permit limit has been set below the level of detection of
previously approved methods. In developing this regulation, EPA
considered the effects on small entities. Section 601(6) of the RFA
defines small entity as small business, small governmental
jurisdiction, and small organization. The small entities that might be
affected by this rule include small governmental jurisdictions (that
own POTWs) and small businesses with discharge permits for mercury at
or below 200 ng/L. Of the 477 entities that we have identified with
mercury limits at or below 200 ng/L, 143 are businesses, 38 are
drinking water treatment plants in Puerto Rico, and 296 are POTWs.
To evaluate the potential impact on small businesses, EPA first
assumed that all of the 143 businesses were small. EPA assigned to each
identified facility the approximate average revenue for a small
business in the SIC code to which that facility belongs. If the
facility is classified as a ``major'' discharger in the Permit
Compliance System (PCS), EPA assumed incremental analytical monitoring
costs of $5,200 per year. This assumption is based upon weekly
monitoring for mercury at two sample locations using Method 1631, and
assumes each facility will incur an incremental cost of $50 per sample
(the high end of the range of incremental costs). If the facility is
classified as a ``minor'' discharger in PCS, EPA assumed incremental
analytical monitoring costs of $600 per year. This assumption is based
upon monthly monitoring for mercury at one sample location using Method
1631, and again assumes each facility will incur the high end
incremental cost of $50 per sample. EPA then calculated the ratio of
costs (using these upper-bound assumptions) to the assigned revenue to
derive an upper-bound estimate of the impacts. The ratio is above 0.5
percent for only three facilities--``major'' facilities, which may not
be small businesses--and in all cases is below 4 percent. On average,
the impacts were much lower. Specifically, the mean ratio for all of
the facilities is 0.17 percent and the median ratio is 0.06 percent.
Although PCS contains limitations data for over 20
[[Page 30432]]
percent of the ``minor'' dischargers, EPA believes that ``minor''
dischargers without limitations data in PCS would have a similarly low
level of impact. No ``minor'' discharger is expected to experience an
impact of more than 0.5 percent of revenues.
Small governments are those representing jurisdictions of less than
50,000 people. The 38 drinking water plants in Puerto Rico are state-
owned and thus are not small governments. To evaluate the impact on
small POTWs, EPA looked at the potential impacts on two sizes of POTWs
to represent both ``major'' and ``minor'' dischargers potentially
affected by the regulation. Based on national estimates from the Census
of Governments, local governments collect $79.31 per person in sewerage
charges, which EPA assumed to be the average per capita revenue for
POTWs from the population that they serve. On average, a POTW has a
flow of 100 gallons per day for each person that it serves. EPA assumed
that a POTW serving 1,000 people (having a flow of 100,000 gallons per
day) would have revenues of $79,310 and incur costs of $600 (using the
same assumptions as for ``minor'' businesses), which is 0.76 percent of
its revenue. Similarly, EPA estimated that a POTW serving 10,000 people
(having a flow of 1 million gallons per day, and thus being a major
discharger) would have revenue of $793,100 and incur costs of $5,200
(using the same assumptions as for ``major'' businesses), which is only
0.66 percent of revenue.
Based upon these estimates, EPA concludes that this rule will not
have a significant economic impact on a substantial number of small
entities.
D. Paperwork Reduction Act
This rule contains no information collection requirements.
Therefore, no information collection request has been submitted to the
Office of Management and Budget (OMB) for review and approval under the
Paperwork Reduction Act of 1995, 44 U.S.C. 3501 et seq.
E. Submission to Congress and the General Accounting Office
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 July 8, 1999.
F. National Technology Transfer and Advancement Act
As noted in the proposed rule, section 12(d) of the National
Technology Transfer and Advancement Act of 1995 (NTTAA), Pub. L. 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, business practices)
that are developed or adopted by voluntary consensus standards bodies.
The NTTAA directs EPA to provide Congress, through the Office of
Management and Budget (OMB), explanations when the Agency decides not
to use available and applicable voluntary consensus standards. This
rulemaking involves technical standards. Therefore, the Agency
conducted a search to identify potentially applicable voluntary
consensus standards. EPA's search of the technical literature revealed
that there are no consensus methods for determination of mercury at
these trace levels, although the American Society of Testing and
Materials (ASTM) potentially is in the process of developing an
analytical method for the determination of trace levels of mercury. If
ASTM or another voluntary consensus standard body approves such a
method and EPA believes that the method is suitable for compliance
monitoring and other purposes, EPA will promulgate the method in a
subsequent rule. As mentioned earlier, the Agency followed ASTM's
Practice D 2777 (a voluntary consensus standard) in the design of EPA's
interlaboratory method validation study for EPA Method 1631.
G. Executive Order 13045
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 E.O. 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 E.O. 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. Although it has been determined that this rule is a
``significant regulatory action'' under E.O. 12866, it is not
economically significant and, therefore, E.O. 13045 does not apply. In
addition, this rule does not establish an environmental standard
intended to mitigate health or safety risks.
H. Executive Order 12875
Under Executive Order 12875, ``Enhancing the Intergovernmental
Partnership,'' EPA may not issue a regulation that is not required by
statute and that creates a mandate upon a State, local or tribal
government, unless the Federal government provides the funds necessary
to pay the direct compliance costs incurred by those governments, or
EPA consults with those governments. If EPA complies by consulting,
E.O. 12875 requires EPA to provide to the Office of Management and
Budget a description of the extent of EPA's prior consultation with
representatives of affected State, local and tribal governments, the
nature of their concerns, any written communications from the
governments, and a statement supporting the need to issue the
regulation. In addition, Executive Order 12875 requires EPA to develop
an effective process permitting elected officials and other
representatives of State, local and tribal governments ``to provide
meaningful and timely input in the development of regulatory proposals
containing significant unfunded mandates.''
Today's rule does not create a mandate on State, local or tribal
governments. States have been particularly supportive of EPA's efforts
to approve a more sensitive test method for mercury. The rule does not
impose any enforceable duties on these entities. This rule makes
available a testing procedure for use when testing is otherwise
required by a regulatory agency. Accordingly, the requirements of
section 1(a) of Executive Order 12875 do not apply to this rule.
I. Executive Order 13084
Under Executive Order 13084, ``Consultation and Coordination with
Indian Tribal Governments,'' EPA may
[[Page 30433]]
not issue a regulation that is not required by statute, that
significantly or uniquely affects the communities of Indian tribal
governments, and that imposes substantial direct compliance costs on
those communities, unless the Federal government provides the funds
necessary to pay the direct compliance costs incurred by the tribal
governments, or EPA consults with those governments. If EPA complies by
consulting, E.O. 13084 requires EPA to provide to the Office of
Management and Budget, in a separately identified section of the
preamble to the rule, a description of the extent of EPA's prior
consultation with representatives of affected tribal governments, a
summary of the nature of their concerns, and a statement supporting the
need to issue the regulation. In addition, Executive Order 13084
requires EPA to develop an effective process permitting elected and
other representatives of Indian tribal governments ``to provide
meaningful and timely input in the development of regulatory policies
on matters that significantly or uniquely affect their communities.''
As described under the Regulatory Flexibility Analysis, today's
rule does not significantly or uniquely affect the communities of
Indian tribal governments. Further, this rule does not impose
substantial direct compliance costs on Tribal governments. This rule
makes available a testing procedure which would be used when testing is
otherwise required by a regulatory agency to demonstrate compliance
with water quality-based permit limits for mercury. Accordingly, the
requirements of section 3(b) of Executive Order 13084 do not apply to
this rule.
List of Subjects in 40 CFR Part 136
Environmental protection, Analytical methods, Incorporation by
reference, Monitoring, Reporting and recordkeeping requirements, Waste
treatment and disposal, Water pollution control.
Dated: May 28, 1999.
Carol M. Browner,
Administrator.
In consideration of the preceding, USEPA amends 40 Code of Federal
Regulations part 136 as follows:
PART 136--GUIDELINES ESTABLISHING TEST PROCEDURES FOR THE ANALYSIS
OF POLLUTANTS
1. The authority citation of 40 CFR part 136 continues to read as
follows:
Authority: Secs. 301, 304(h), 307, and 501(a), Pub. L. 95-217,
Stat. 1566, et seq. (33 U.S.C. 1251, et seq.) (The Federal Water
Pollution Control Act Amendments of 1972 as amended by the Clean
Water Act of 1977).
2. Section 136.3, paragraph (a), Table IB.--List of Approved
Inorganic Test Procedures, is amended by revising entry 35 to read as
follows:
Sec. 136.3 Identification of test procedures.
(a) * * *
* * * * *
Table IB--List of Approved Inorganic Test Procedures
----------------------------------------------------------------------------------------------------------------
Reference (method number or page)
----------------------------------------------------------------------------------
Parameter, units and method STD methods 18th
EPA 1,35 ed. ASTM USGS \2\ Other
----------------------------------------------------------------------------------------------------------------
* * * * * *
*
35. Mercury--Total,\4\ mg/L:
Cold vapor, manual, or... 245.1 3112 B.......... D3223-91........ I-3462-85....... \3\ 977.22
Automated................ 245.2 ................ ................ ................ ..............
Oxidation, purge and \43\ 1631 ................ ................ ................ ..............
trap, and cold vapor
atomic fluorescence
spectrometry (ng/L).
* * * * * *
*
----------------------------------------------------------------------------------------------------------------
Table 1B Notes:
\1\ ``Methods for Chemical Analysis of Water and Wastes,'' Environmental Protection Agency, Environmental
Monitoring Systems Laboratory--Cincinnati (EMSL-CI), EPA-600/4-79-020, Revised March 1983 and 1979 where
applicable.
\2\ Fishman, M.J., et al. ``Methods for Analysis of Inorganic Substances in Water and Fluvial Sediments'', U.S.
Department of the Interior, Techniques of Water--Resource Investigations of the U.S. Geological Survey,
Denver, CO, Revised 1989, unless otherwise stated.
\3\ ``Official Methods of Analysis of the Association of Official Analytical Chemists,'' methods manual, 15th
ed. (1990).
\4\ For the determination of total metals the sample is not filtered before processing. A digestion procedure is
required to solubilize suspended material and to destroy possible organic-metal complexes. Two digestion
procedures are given in ``Methods for Chemical Analysis of Water and Wastes, 1979 and 1983.'' One (Section
4.1.3), is a vigorous digestion using nitric acid. A less vigorous digestion using nitric and hydrochloric
acids (Section 4.1.4) is preferred; however, the analyst should be cautioned that this mild digestion may not
suffice for all sample types. Particularly, if a colorimetric procedure is to be employed, it is necessary to
ensure that all organo-metallic bonds be broken so that the metal is in a reactive state. In those situations,
the vigorous digestion is to be preferred making certain that at no time does the sample go to dryness.
Samples containing large amounts of organic materials may also benefit by this vigorous digestion, however,
vigorous digestion with concentrated nitric acid will convert antimony and tin to insoluble oxides and render
them unavailable for analysis. Use of ICP/AES as well as determinations for certain elements such as antimony,
arsenic, the noble metals, mercury, selenium, silver, tin, and titanium require a modified sample digestion
procedure and in all cases the method write-up should be consulted for specific instructions and/or cautions.
Note to Table IB Note 4: If the digestion procedure for direct aspiration AA included in one of the other
approved references is different than the above, the EPA procedure must be used. Dissolved metals are defined
as those constituents which will pass through a 0.45 micron membrane filter. Following filtration of the
sample, the referenced procedure for total metals must be followed. Sample digestion of the filtrate for
dissolved metals (or digestion of the original sample solution for total metals) may be omitted for AA (direct
aspiration or graphite furnace) and ICP analyses, provided the sample solution to be analyzed meets the
following criteria:
a. has a low COD (<20), b.="" is="" visibly="" transparent="" with="" a="" turbidity="" measurement="" of="" 1="" ntu="" or="" less,="" c.="" is="" colorless="" with="" no="" perceptible="" odor,="" and="" d.="" is="" of="" one="" liquid="" phase="" and="" free="" of="" particulate="" or="" suspended="" matter="" following="" acidification.="" *="" *="" *="" *="" *="" \35\="" precision="" and="" recovery="" statements="" for="" the="" atomic="" absorption="" direct="" aspiration="" and="" graphite="" furnace="" methods,="" and="" for="" the="" spectrophotometric="" sddc="" method="" for="" arsenic="" are="" provided="" in="" appendix="" d="" of="" this="" part="" titled,="" ``precision="" and="" recovery="" statements="" for="" methods="" for="" measuring="" metals.''="" *="" *="" *="" *="" *="" \43\="" the="" application="" of="" clean="" techniques="" described="" in="" epa's="" draft="" method="" 1669:="" sampling="" ambient="" water="" for="" trace="" metals="" at="" epa="" water="" quality="" criteria="" levels="" (epa-821-r-96-011)="" are="" recommended="" to="" preclude="" contamination="" at="" low-level,="" trace="" metal="" determinations.="" [[page="" 30434]]="" 3.="" section="" 136.3="" is="" amended="" by="" adding="" new="" paragraph="" (40)="" to="" read="" as="" follows:="" sec.="" 136.3="" identification="" of="" test="" procedures.="" (a)="" *="" *="" *="" (b)="" *="" *="" *="" *="" *="" *="" *="" *="" (40)="" usepa.="" 1999.="" method="" 1631,="" revision="" b,="" ``mercury="" in="" water="" by="" oxidation,="" purge="" and="" trap,="" and="" cold="" vapor="" atomic="" fluorescence="" spectrometry.''="" may="" 1999.="" office="" of="" water,="" u.s.="" environmental="" protection="" agency="" (epa="" 821-r-99-005).="" available="" from:="" national="" technical="" information="" service,="" 5285="" port="" royal="" road,="" springfield,="" virginia="" 22161.="" publication="" no.="" pb99-131989.="" cost:="" $25.50.="" table="" ib,="" note="" 43.="" *="" *="" *="" *="" *="" [fr="" doc.="" 99-14220="" filed="" 6-7-99;="" 8:45="" am]="" billing="" code="" 6560-50-p="">