[Federal Register Volume 67, Number 209 (Tuesday, October 29, 2002)]
[Rules and Regulations]
[Pages 65876-65888]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-27136]


-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 136

[FRL-7390-6]
RIN 2040-AD72


Guidelines Establishing Test Procedures for the Analysis of 
Pollutants; Measurement of Mercury in Water; Revisions to EPA Method 
1631

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This action approves EPA Method 1631, Revision E: Mercury in 
Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence 
Spectrometry (Method 1631E) for determination of mercury in aqueous 
samples. Today's rule replaces the currently approved version of Method 
1631 and includes revisions that address stakeholder concerns. EPA 
Method 1631E clarifies quality control and sample handling requirements 
and allows flexibility to incorporate additional available 
technologies. This rule also amends the requirements regarding 
preservation, storage, and holding time for low level mercury samples.

DATES: This final rule is effective on November 23, 2002. For judicial 
review purposes, this final rule is promulgated as of 1 p.m. Eastern 
Standard Time on November 12, 2002 in accordance with 40 CFR 23.7. The 
incorporation by reference of EPA Method 1631, Revision E, is approved 
by the Director of the Federal Register as of November 23, 2002.

FOR FURTHER INFORMATION CONTACT: William Telliard; Engineering and 
Analysis Division (4303T); Office of Science and Technology; Office of 
Water; U.S. Environmental Protection Agency; Ariel Rios Building; 1200 
Pennsylvania Avenue, NW., Washington, DC 20460, or call (202) 566-1061 
or e-mail at [email protected].

SUPPLEMENTARY INFORMATION:

A. 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, NPDES permitting authorities, 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'' (i.e., promulgated through rulemaking) standardized 
testing procedures for a given pollutant, the NPDES permitting 
authority must specify one of the approved testing procedures or an 
approved alternate test procedure for the measurements required under 
the permit. In addition, when an authorized State, Territory, or Tribe 
provides certification of Federal licenses under Clean Water Act 
section 401, States, Territories and Tribes are directed to use the 
approved testing procedures. Categories and entities that may be 
regulated include:

------------------------------------------------------------------------
                                               Examples of potentially
                 Category                        regulated entities
------------------------------------------------------------------------
State, Territorial, and Indian Tribal       States, Territories, and
 Governments.                                Tribes authorized to
                                             administer the NPDES
                                             permitting program; States,
                                             Territories, and Tribes
                                             providing certification
                                             under Clean Water Act
                                             section 401.
Industry..................................  Private facilities required
                                             to monitor.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be

[[Page 65877]]

regulated. To determine whether your facility or organization is 
regulated by this action, you should carefully examine the 
applicability language at 40 CFR 136.1 (NPDES permits and CWA). 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 SECTON.

B. How Can I Get Copies of This Document and Other Related Information?

    1. Docket. EPA has established an official public docket for this 
action under Docket ID No. W-01-05. The official public docket consists 
of the documents specifically referenced in this action, any public 
comments received, and other information related to this action. 
Although a part of the official docket, the public docket does not 
include Confidential Business Information (CBI) or other information 
whose disclosure is restricted by statute. The official public docket 
is the collection of materials that is available for public viewing at 
the Water Docket located at EPA West Building, Room B135, 1301 
Constitution Avenue, Washington, DC. This Docket Facility is open from 
8:30 a.m. and 4:30 p.m. Eastern Time, Monday through Friday, excluding 
Federal holidays. The Docket telephone number is 202-566-2426.
    2. Electronic Access. You may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.epa.gov/fedrgstr/.{time} 
    An electronic version of the public docket is available through 
EPA's electronic public docket and comment system, EPA Dockets. You may 
use EPA Dockets at http://www.epa.gov/edocket/ to view public comments, 
access the index listing of the contents of the official public docket, 
and to access those documents in the public docket that are available 
electronically. Although not all docket materials may be available 
electronically, you may still access any of the publicly available 
docket materials through the docket facility identified in Unit I.B. 
Once in the system, select ``search,'' then key in the appropriate 
docket identification number.

Outline of Document

I. Statutory Authority
II. Background
    A. Regulatory History
    B. Settlement Agreement
    C. Proposed Rule
III. Summary of Final Rule
    A. EPA Method 1631, Revision E
    B. Amendment to 40 CFR 136.3(e) Table II
IV. Changes from the October 9, 2001 Proposed Rule
    A. Additional Requirements for Clean Techniques and Quality 
Control Provisions
    B. Election by a Permittee or Industrial User
    C. Additional Revisions to EPA Method 1631
    D. Extension of Holding Time for Unpreserved Samples
    E. Clarifications and Corrections
V. Response to Major Comments
    A. Performance-Based Measurement System
    B. Proposed Requirements for Clean Techniques
    C. Election by a Permittee or Industrial User
    D. Bottle Blanks
    E. Range of Method Calibration
    F. Acceptance Criteria Associated with Blank Samples
    G. Flow-Injection Systems
    H. Sample Containers
    I. Carryover
    J. Other Technical Details
VI. Administrative Requirements
    A. Executive Order 12866: Regulatory Planning and Review
    B. Regulatory Flexibility Act (RFA), as Amended by the Small 
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 
U.S.C. 601 et seq.
    C. Unfunded Mandates Reform Act
    D. Paperwork Reduction Act
    E. National Technology Transfer and Advancement Act
    F. Executive Order 13045: Protection of Children from 
Environmental Health Risks and Safety Risks
    G. Executive Order 13132: Federalism
    H. Executive Order 13175: Consultation and Coordination with 
Indian Tribal Governments
    I. Congressional Review Act
    J. Executive Order 13211: Energy Effects
    K. Plain Language Directive

I. Statutory Authority

    Today's rule is promulgated pursuant to the authority of sections 
301, 304(h), 307, and 501(a) of the Clean Water Act (CWA), 33 U.S.C. 
1311, 1314(h), 1317, 1361(a) (the ``Act'' or ``CWA''). 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 ``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 parts 122, Sec. Sec.  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, 
Sec. Sec.  403.10 and 402.12).

II. Background

A. Regulatory History

    On May 26, 1998, EPA proposed EPA Method 1631 at 40 CFR part 136 
for use in determining mercury at ambient water quality criteria levels 
in EPA's Clean Water Act programs (63 FR 28867). On March 5, 1999, EPA 
published a Notice of Data Availability that included additional data 
supporting the application of EPA Method 1631 to effluent matrices (64 
FR 10596), and on June 8, 1999, published a final rule promulgating EPA 
Method 1631, Revision B: Mercury in Water by Oxidation, Purge and Trap, 
and Cold Vapor Atomic Fluorescence Spectrometry (64 FR 30416) at 40 CFR 
part 136. Following method promulgation, EPA published a technical 
correction replacing Revision B (Method 1631B) with EPA Method 1631, 
Revision C (66 FR 32774; June 18, 2001). Revision C clarified the 
method text regarding the reporting and use of field blanks.

B. Settlement Agreement

    Following promulgation of EPA Method 1631B on June 8, 1999, several 
industry groups filed a petition for judicial review of the method. On 
October 19, 2000, EPA entered into a Settlement Agreement (Alliance of 
Automobile Manufacturers, et al. v. EPA, No. 99-1420, D.C. Dir.) with 
the Petitioners. The Settlement Agreement includes three clauses that 
address revisions to EPA Method 1631 (Clauses 2, 3, and 4). Clauses 2 
and 3 committed EPA to sign a notice of final rulemaking by June 15, 
2001, revising sections 12.4.2 and 9.4.3.3 of EPA Method 1631B to 
clarify the use of field blanks. EPA complied with that commitment. On 
June 18, 2001, EPA published a notice of final rulemaking announcing a 
revised version of EPA Method 1631 (Revision C; Method 1631C).
    Clause 4 of the Settlement Agreement required that EPA sign a 
notice for publication in the Federal Register to propose additional 
requirements for certain clean techniques and quality control (QC) 
provisions on or before September 30, 2001, and to sign a notice

[[Page 65878]]

for final action on the proposal on or before September 30, 2002. On 
October 9, 2001, EPA published a notice proposing such revisions (66 FR 
51518). At that time, EPA also made a draft of the method available to 
present the proposed revisions in context of EPA Method 1631 procedures 
(draft Method 1631, Revision D). Today's action satisfies EPA's 
obligation to take final action on the proposed rulemaking.

C. Proposed Rule

    On October 9, 2001, EPA proposed revisions to Method 1631 under the 
Settlement Agreement (66 FR 51518). The proposed revisions were listed 
in Appendix A of the Settlement Agreement and were presented in Section 
IV of the proposed rule (66 FR 51520). The proposed revisions would 
have converted certain of the recommendations and guidance in the 
method (specifically, certain clean techniques and quality control 
provisions) into requirements. The proposal would have allowed an NPDES 
permittee to forgo such requirements at their own discretion, but at 
their own risk. The proposal would not have allowed other method users 
(e.g., State agencies) to forgo the proposed requirements.
    EPA proposed several additional revisions that were not contested 
in the litigation. These latter proposals would clarify method 
procedures, increase method flexibility, and provide additional 
guidance for method implementation. To ensure consistency with 
analytical method requirements, EPA also proposed an amendment to Table 
II at 40 CFR 136.3(e) to address collection and handling of samples for 
analysis using EPA Method 1631. The additional proposed revisions and 
the proposed amendment to Table II at 40 CFR 136.3(e) were based on 
comments and recommendations submitted to EPA by various stakeholders 
since promulgation of EPA Method 1631B in June of 1999. EPA received 26 
comment packages on the October 2001 proposed rule. Section V of this 
document summarizes the major comments. The administrative record 
supporting today's action responds to the public comments received on 
all the proposed changes.

III. Summary of Final Rule

A. EPA Method 1631, Revision E

    Today's action replaces all previously approved versions of EPA 
Method 1631 with EPA Method 1631, Revision E (Method 1631E) for 
measurement of mercury in aqueous samples. Today's action does not 
repeal any other currently approved methods that measure mercury. EPA 
Method 1631E (the ``Method'') incorporates several revisions to 
increase method flexibility and improve data quality. These revisions:
    [sbull] Allow the use of automated flow-injection systems (Sections 
10.3 and 11.2.2);
    [sbull] Incorporate system blanks for use with automated flow-
injection systems (Sections 9.4.2 and 10.3.2);
    [sbull] Incorporate definitions for blank samples (Sections 9.4 and 
17);
    [sbull] Incorporate a requirement for analysis of method blanks 
(Section 9.4);
    [sbull] Include a requirement to analyze bottle blanks at a 
recommended minimum frequency of 5 percent (Sections 6.1.2.4 and 
9.4.7);
    [sbull] Allow extension of the calibration range (Sections 1.3 and 
10.4);
    [sbull] Remove requirements for immediate sample preservation, 
refrigeration of unpreserved samples, and collection of samples with 
zero headspace, provided sample bottles are tightly capped and samples 
are either preserved or analyzed within 48 hours of collection (Section 
8.5).
    [sbull] Allow extension of the time until preservation to 28 days 
if a sample is oxidized in its sample container (Section 8.5);
    [sbull] Extend the maximum sample holding time (time from sample 
collection until sample analysis) from 28 days to 90 days (Section 
8.5);
    [sbull] Incorporate a carryover test for determining the amount of 
mercury that would be carried into a subsequent sample when a sample 
containing a high level of mercury is analyzed (Sections 4.2.8.1 and 
11.2);
    [sbull] Further clarify that samples must be completely oxidized 
prior to analysis (Section 8.1);
    [sbull] Allow shipment of empty bottles for sample collection 
(Section 6.1.2.1);
    [sbull] Incorporate a requirement for analysis of a minimum of two 
matrix spike/matrix spike duplicate (MS/MSD) sample pairs per 
analytical batch of twenty samples (Section 11.1.2);
    [sbull] Reinforce the requirement that only glass or fluoropolymer 
bottles may be used for sample collection (Section 4.3.7.1 and 8.2);
    [sbull] Allow both field and laboratory sample filtration (Sections 
2.2 and 8.4);
    [sbull] Correct part numbers (Sections 6.1.3.2 and 6.1.3.3); and
    [sbull] Clarify that method users are permitted to omit steps or 
modify procedures provided that all performance requirements in the 
Method are met, but must not omit or modify any procedure defined by 
the term ``shall'' or ``must,'' and must perform all quality control 
tests (Method introductory note).

B. Amendment to 40 CFR 136.3(e), Table II

    Today's rule also amends 40 CFR 136.3(e) by adding a footnote (17) 
to Table II to include requirements for collection, filtration, 
preservation, and maximum holding times that are specific to samples 
collected for determination of mercury using EPA Method 1631. This 
footnote includes the following requirements for mercury samples: 
samples must be collected in either fluoropolymer or glass containers; 
samples must be preserved with either HCl or BrCl within 48 hours of 
collection; time until preservation may be extended to 28 days if 
samples are oxidized in the sample bottles; samples have a maximum 
holding time of 90 days from the date of sample collection; and samples 
must be filtered in a clean area in the laboratory or in the field 
prior to sample preservation. This amendment provides consistency with 
requirements approved in previous versions of EPA Method 1631 and with 
the revisions promulgated today.

IV. Changes from the October 9, 2001 Proposed Rule

A. Additional Requirements for Clean Techniques and Quality Control 
Provisions

    Under the Settlement Agreement, EPA proposed certain clean 
techniques and quality control (QC) provisions as requirements. Under 
the then existing versions of Method 1631, these provisions were only 
recommendations. These provisions were presented in Section IV.A of the 
proposed rule and were indicated throughout draft Method 1631D by the 
word ``must'' in bracketed and italicized text. A summary of the 
comments received and EPA's response to the comments is presented in 
Section V.B of this document.
    Commenters generally opposed the changes from ``should'' to 
``must,'' maintaining that Method 1631 and other EPA methods should be 
``performance based''; i.e., that the method user should be accorded 
flexibility to improve method performance and lower the costs of 
measurements, provided all performance criteria are met. However, 
commenters supported specific requirements for analysis of bottle 
blanks (Sections 6.1.2.3 and 9.4.7), analysis of blanks to test for 
carryover (Sections 4.3.8.1 and 11.2), analysis of two MS/MSD pairs per 
each analytical batch of 20 samples (Section 11.1.2), and use of either 
fluoropolymer or glass containers for sample collection

[[Page 65879]]

(Section 4.3.7.1). In response to comments, EPA is incorporating these 
changes into EPA Method 1631E in today's rule.
    Following review of comments, EPA believes that requiring the 
additional proposed requirements for clean techniques or quality 
control provisions would result in unnecessary economic burden and 
would limit future use of the Method. With the exceptions outlined 
above, EPA is not promulgating the clean techniques and quality control 
requirements proposed earlier. Instead, EPA has retained in the Method 
as recommendations that samples should be collected using clean hands/
dirty hands collection procedures (Section 9.4.4.2); samples should be 
processed in a clean room or clean bench (Sections 4.3.3 and 8.5.3); 
exposure to sources of contamination should be minimized (Section 4.3); 
work surfaces should be cleaned prior to processing sample batches 
(Section 4.3.5); traps that tend to absorb large quantities of water 
vapor should be pre-dried or discarded (Section 4.3.3); outside air, if 
clean, should be brought into the clean bench air intake (Section 7.2); 
samples should be stored in clean, new polyethylene bags prior to use 
(Section 8.6); and samples collected for measurement of methylmercury 
should be collected and preserved according to procedures required in 
the analytical method that will be used (Sections 2.3 and 8.5).

B. Election by a Permittee or Industrial User

    Under the Settlement Agreement, EPA also proposed that an NPDES 
permittee or an industrial user of a POTW be able to elect not to 
implement the clean techniques and QC provisions ``in its discretion 
and at its peril, unless specifically provided otherwise by the 
relevant permitting agency or pretreatment control authority, as the 
case may be.'' The election, if promulgated, would apply only to those 
clean techniques and QC provisions designated in the Settlement 
Agreement and designated by bracketed and italicized text throughout 
draft Method 1631D. Because EPA is not imposing such requirements, EPA 
has not included the proposed election revision in today's final rule. 
A summary of the comments regarding the proposed option and EPA's 
response to the comments is presented in Section V.C of this document.

C. Additional Revisions to EPA Method 1631

    Since promulgation of EPA Method 1631B in June 1999, EPA received 
many suggestions from Method users for improving method flexibility and 
clarifying certain method procedures. EPA proposed and discussed these 
improvements and clarifications in the October 9, 2001 proposal. In 
today's final rule, EPA is withdrawing or revising certain proposed 
Method revisions based on adverse comments. Specifically, EPA is (1) 
revising the term ``calibration blank'' to ``system blank'' for those 
blank samples required during calibration and batch analyses when using 
a flow-injection system, (2) revising the proposed QC acceptance 
criteria associated with system blanks and the use of these blanks, (3) 
withdrawing the frequency requirement associated with analysis of 
bottle blanks, and (4) withdrawing the requirement to commensurately 
raise the lowest calibration point when the upper end of the 
calibration range is raised. These four revisions and the corresponding 
comments on the proposed rule are described in more detail in Sections 
V.E through V.F of this document.

D. Extension of Holding Times for Unpreserved Samples

    In the October 9, 2001 proposal, EPA stated that it was reviewing 
data that indicate samples collected for measurement of low level 
mercury may be stable for as long as 35 days prior to preservation, and 
included the data in the Record supporting the proposed rule. At that 
time, EPA also solicited additional data or comments regarding the 
stability of unpreserved samples.
    EPA received comments on the proposed rule that support extension 
of the time prior to preservation and has completed review of the data 
discussed in the proposed rule. In response to these data and to 
submitted comments, EPA is requiring in Method 1631E that samples must 
be preserved within 48 hours of sample collection. However, EPA is 
allowing extension of the time until preservation to 28 days if samples 
are oxidized in the sample bottles. EPA has included this change in 
Section 8.5 of EPA Method 1631E and in Footnote 17 to Table II at 40 
CFR 136.3(e).

E. Clarifications and Corrections

    Minor clarifications and technical corrections are included in EPA 
Method 1631E to address errors and inconsistencies noted by commenters. 
These changes and corrections:
    [sbull] Revise Section 9.4.2 to clarify that system blanks are 
specific to flow-injection systems;
    [sbull] Revise Section 9.4.3.1 to clarify that in order to assess 
possible contamination from reagents, reagent blanks include 
hydroxylamine hydrochloride solution in addition to BrCl solution;
    [sbull] Revise Section 11.2.2.1 to clarify that the amount of 
NH2OH required will be approximately 30 percent of the BrCl 
volume;
    [sbull] Revise the QC acceptance criteria for reagent blanks in 
Section 9.4.3 from 0.25 ng/L to 0.2 ng/L for consistency with reporting 
requirements;
    [sbull] Revise Section 12.2.1 to clarify that the mean peak 
response for bubbler blanks measured during calibration or with each 
analytical batch is used for calculating sample results;
    [sbull] Correct the concentration units in the equations in 
Sections 12.2.2 and 12.3.2;
    [sbull] Revise Section 9.3.2.2 to clarify that identical volumes of 
spiking solution must be used for MS/MSD samples;
    [sbull] Revise Section 4.4.1 to clarify that, for those samples 
requiring pre-reduction with SnCl2 (i.e., samples containing 
iodide concentrations greater than 3 mg/L), the SnCl2 should 
be added in a closed vessel or analysis should proceed immediately;
    [sbull] Revise Section 11.1.1.2 to clarify that samples containing 
high organic content may also be diluted to reduce the amount of BrCl 
that may be required, provided that the resulting level of mercury is 
sufficient for reliable determination within the range of method 
calibration;
    [sbull] Revise Section 7 to include a note clarifying that the 
quantities of reagents and the preparation procedures are for 
illustrative purposes. A laboratory may use quantities of reagents and 
procedures that differ, provided it is able to demonstrate equivalent 
performance;
    [sbull] Revise Sections 7.9 and 7.10 to clarify that standard 
solutions should be replaced monthly, or longer if extended stability 
is demonstrated;
    [sbull] Correct Section 2.7 to include the analytical trap in the 
description;
    [sbull] Revise Section 9.1.7 and Section 10.1 to clarify that 
analysis of samples may proceed without recalibration, provided system 
performance is verified at the end of the analytical sequence;
    [sbull] Revise Section 9.4 to address the performance criteria 
associated with blank samples in those circumstances when a method 
detection limit greater than 0.2 ng/L is sufficient to address 
compliance monitoring;
    [sbull] Include a note in Section 9.1.2.1 to clarify that 
acceptance criteria associated with blank samples may be adjusted to 
support measurements at the compliance level; and
    [sbull] Revise Section 12.5.1 to include specifications for 
reporting results of Method blanks.

[[Page 65880]]

V. Response to Major Comments

    EPA requested comments on the various EPA Method 1631 revisions 
detailed in the October 9, 2001 proposal, and requested data supporting 
comments, if available. Twenty five stakeholders provided comments on 
the proposal addressing over 50 separate issues. Stakeholders included 
10 laboratories, 6 POTWs, 3 regulatory authorities, 3 industries/
industry groups, one instrument manufacturer, a group of several POTWs, 
and the Petitioners (see Settlement Agreement discussion, Section 
II.B).
    The following section summarizes major comments received on the 
proposed rule and EPA's response. The complete Response to Comments 
document can be found in the public record for this final rule (Record 
Section VI, DCN B.1).

A. Performance-Based Measurement System

    Several commenters on the October 9, 2001 proposed rule noted that 
Section 1.8 of EPA Method 1631 describes the method as performance-
based, and that if certain recommendations for clean techniques 
included in the method were to become requirements as proposed, the 
method would no longer be performance-based. Commenters stated that 
requiring laboratories and sample collectors to adopt clean procedures 
that are unnecessary is contrary to a performance-based measurement 
system, and added that additional requirements would impose cost 
burdens that could result in reduced method implementation. Commenters 
stated further that performance-based measurements must not prescribe 
particular actions unless they are essential to the successful 
implementation of the method. Commenters added that many of the 
proposed requirements would lock users into current technology despite 
the many advances and improvements in techniques and equipment that are 
likely to occur in the coming decades. Commenters believe that if the 
performance-based nature of the method is not retained, further 
improvement of method performance would be hindered.
    EPA developed performance-based measurement systems as part of 
EPA's commitment to reducing unnecessary regulatory burden and 
encouraging the use of emerging and innovative technologies. Throughout 
development of these analytical methods, EPA recognized that allowance 
for this flexibility must be matched with controls to ensure that data 
quality is maintained. For this reason, many approved methods include 
standardized QC tests and specific QC acceptance criteria that must be 
met when a method is modified to overcome interferences or lower the 
cost of measurement.
    The QC acceptance criteria included in EPA Method 1631 were 
developed using method validation data from 12 laboratories. These 
criteria include precision and recovery performance requirements for 
the matrix spike and matrix spike duplicate (MS/MSD), initial and 
ongoing precision and recovery (IPR and OPR), calibration linearity, 
method detection limit (MDL), and quality control samples (QCS). EPA 
Method 1631 criteria also include requirements for several blanks 
(i.e., equipment, bottle, field, method, reagent, system, and bubbler 
blanks) to monitor potential contamination during sample collection and 
analysis.
    EPA acknowledges the concerns submitted by commenters and agrees 
that the QC requirements and acceptance criteria in EPA Method 1631 are 
sufficient to ensure data quality and preclude inadequate method 
implementation. For these and other reasons given in the Response to 
Comments document, EPA has decided not to require most of the clean 
techniques and quality control provisions proposed.

B. Proposed Requirements for Clean Techniques

    Only comments submitted on behalf of the Petitioners supported 
promulgation of all the proposed requirements for the additional clean 
techniques specified in the Settlement Agreement. This commenter stated 
that clean sampling and analytical techniques are critical to obtaining 
reliable results for use in the regulatory process. The commenter 
stated further that, although clean techniques result in additional 
expense, the consequences could be more serious if data users act upon 
test results that may be affected by contamination.
    Nineteen commenters submitted comments opposing these additional 
requirements. These commenters believe that EPA Method 1631 contains 
sufficient QC to determine the source of any contamination and that if 
a laboratory can demonstrate it is capable of meeting the Method QC 
criteria without the additional proposed clean techniques, it should be 
allowed to do so. Several commenters stated that the reasoning behind 
the proposed requirements appears to be arbitrary and that it is 
unclear what scientific basis was used to determine which techniques 
should be requirements. Commenters noted that the requirements would 
place a burden, operational and economic, on facilities with little or 
no gain in analytical performance, and could severely limit the ability 
of regulators to determine whether mercury discharges are being 
controlled effectively. At least one POTW commenter stated that, if 
these requirements were promulgated as proposed, it most likely would 
no longer use EPA Method 1631. Additionally, a regulatory authority 
noted that if costs escalate because of additional requirements, such 
costs would limit the ability of regulators to determine whether 
mercury discharges are being controlled effectively.
    EPA agrees with the majority of commenters and believes that the 
additional requirements proposed to be included in EPA Method 1631 
would be burdensome, and that the QC acceptance criteria included in 
the Method are sufficient to ensure data quality. EPA has not received 
data to support a decision that the proposed additional clean 
techniques and quality control provisions are necessary to ensure 
validity of data obtained through implementation of EPA Method 1631. 
The requirements and criteria associated with quality control and blank 
samples throughout the Method are the most appropriate and valuable 
means for identifying and controlling contamination.
    Additionally, EPA believes that if all of the recommendations for 
clean techniques were required, compliance with the requirements would 
be extremely difficult to monitor. For example, EPA proposed to revise 
Method 1631 Section 4.3.8.4 as follows: ``* * * Whenever possible, 
sample processing and analysis [must] occur as far as possible from 
sources of airborne contamination.'' Following review of comments, EPA 
believes that it does not have sufficient information to provide 
specific tests to determine compliance with such a requirement. EPA 
believes the most appropriate means for demonstrating that samples are 
processed and analyzed using procedures to minimize contamination are 
already included in the requirements and criteria for analysis of 
blanks, and that analysts are appropriately advised regarding how to 
avoid contamination by the recommendations for clean techniques in the 
Method.
    EPA also recognizes that sample locations and laboratory 
environments can differ significantly and that the site-specific clean 
techniques necessary to meet the performance criteria included in EPA 
Method 1631 will be best

[[Page 65881]]

determined and improved upon by individual Method users. For these 
reasons, and to respond to the concerns of commenters, EPA is retaining 
the clean techniques provisions as recommendations but not requirements 
in EPA Method 1631E. EPA Method 1631E continues to require that all QC 
tests be performed and that all QC acceptance criteria are met, and 
continues to include the following as recommendations:
    [sbull] Use a clean room or clean bench for sample preparation and 
analysis (Sections 4.3.3 and 8.5.3);
    [sbull] Minimize exposure of the apparatus to contamination 
(Section 4.3.3);
    [sbull] Clean work surfaces prior to processing sample batches 
(Section 4.3.5);
    [sbull] Process samples as far as possible from sources of airborne 
contamination (Section 4.3.8.4);
    [sbull] Ensure that laboratory air is low in mercury (Section 7.2);
    [sbull] Store sample bottles in clean (new) polyethylene bags until 
sample analysis (Section 8.6); and
    [sbull] Use ``Clean Hands/Dirty Hands'' techniques described in 
EPA's Method 1669: Sampling Ambient Water for Trace Metals at EPA Water 
Quality Criteria Levels for collection of equipment blanks (Section 
9.4.4.2).
    In addition to recommending these protocols for clean techniques 
throughout EPA Method 1631E, EPA published several guidance documents 
supporting the collection and analysis of samples for measurement of 
low-level mercury. These guidance documents include Guidance for 
Implementation and Use of Method 1631 for Determination of Low-Level 
Mercury (40 CFR Part 136) EPA 821-R-01-023, March 2001; Method 1669: 
Sampling Ambient Water for Trace Metals at EPA Water Quality Criteria 
Levels, 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.

C. Election by a Permittee or Industrial User

    Under the Settlement Agreement, EPA proposed to require specific 
clean techniques and QC provisions in draft Method 1631D and to provide 
only NPDES permittees and industrial users with the option not to 
implement those techniques and provisions.
    Comments submitted on behalf of the Petitioners regarding this 
proposed option state that this approach would be appropriate because 
(1) the liability associated with sampling lies with the permittee and, 
therefore, the permittee should have the discretion to determine what 
is or is not an acceptable contamination risk, (2) permittees are 
familiar with the characteristics of their effluent and the level to 
which clean techniques must be followed, and (3) EPA and State agencies 
lack this level of facility-specific understanding and therefore, 
should be required to follow clean procedures. The commenter added 
that, under the current system, permittees may be precluded from 
raising the contamination issue as a defense in an enforcement action 
or, at a minimum, would bear the very heavy burden of proving 
contamination for data generated by EPA or State agencies.
    Eleven commenters stated that giving certain groups the option to 
eliminate certain requirements for clean techniques and QC provisions 
would result in a plethora of methods and would make it very difficult 
for contract testing laboratories who would bear the burden of the 
resulting confusion. Some permittees may elect to forgo required clean 
techniques while others would not; all laboratory customers, however, 
would benefit and bear costs of clean techniques, regardless of their 
election. These commenters believe that such an option would set a 
dangerous and undesirable precedent regarding what any particular 
person believes is ``necessary'' to achieve a scientifically valid 
result. These commenters stated further that implementation of this 
option would limit the quality and value of collective databases for 
environmental decision making.
    In today's final rule, EPA is not requiring most of the proposed 
clean techniques and QC provisions for any users of the Method. EPA 
agrees with the majority of commenters that applying such requirements 
to only some users would create unwanted inconsistency, would severely 
impair laboratories serving multiple clients, and would ultimately 
cause misinterpretation of data and confusion among regulators and 
laboratories. Most importantly, EPA disagrees with the comment that all 
of the proposed clean techniques are necessary to obtain reliable 
results. EPA also disagrees with the comment that Federal and State 
laboratories lack the necessary information (or even need facility-
specific information) to minimize contamination. In today's final rule, 
EPA has not included this option in EPA Method 1631E.
    Rather than requiring the clean techniques and QC provisions for 
some users but not for others, EPA instead is providing equal 
flexibility for all users of the Method. Most of the clean techniques 
and QC provisions are included only as recommendations in the final 
rule. Because EPA is not requiring most of the proposed clean 
techniques and QC provisions for any users of the Method, there is no 
reason to include the option for permittees and industrial users to 
elect not to use them, and in today's final rule, EPA has not included 
this option.

D. Bottle Blanks

    EPA proposed to revise EPA Method 1631 to include requirements to 
assess cleanliness of bottle blanks and to require analysis of bottle 
blanks at a minimum frequency of 20 percent from a given lot. Most 
commenters agreed that requiring analysis of bottle blanks is 
appropriate and good practice. However, only one comment submitted 
regarding these blank samples supported a requirement that bottle 
blanks be analyzed at a frequency of 20 percent. EPA received comments 
from 7 laboratories, 1 instrument manufacturer, and 1 regulatory 
authority that this frequency requirement is excessive, and would 
result in unnecessary additional equipment costs. Commenters also 
provided cost information suggesting that, if one assumes a low cost of 
between $40 and $50 per Method 1631 analysis performed, this 
requirement would add a cost of $800 to $1000 per lot of clean bottles, 
or approximately $8 to the cost of each bottle purchased. Commenters 
also recommended alternate frequency requirements for bottle blank 
testing ranging from a minimum of 1 percent to 10 percent.
    EPA's proposal to include a requirement that a minimum of 20 
percent of the bottles from a given lot be tested for cleanliness was 
based on current practices implemented in a single laboratory. Because 
method and field blanks also are used to monitor contamination and are 
required in EPA Method 1631E, EPA agrees that requiring testing of 20 
percent of the bottles from each lot is unnecessary and probably 
excessive. Although laboratories and cleaning facilities may choose to 
test at this frequency as a means of ensuring contamination control, 
EPA is not requiring that frequency in today's rule. EPA believes that 
testing a lot of bottles at a minimum frequency of 5% is sufficient and 
has included this frequency as a recommendation in EPA Method 1631E. 
While EPA is recommending that bottle blanks be analyzed at a frequency 
of 5%, laboratories have demonstrated the ability to meet EPA Method 
1631 performance criteria and data quality

[[Page 65882]]

objectives analyzing bottle blanks at a minimum frequency of 1%. 
Therefore, if a laboratory is able to meet performance criteria using a 
minimum frequency of 1%, it should be allowed.

E. Range of Method Calibration

    In response to several requests from stakeholders to apply EPA 
Method 1631 across a broader range, EPA proposed to allow calibration 
to a lower point (below the ML) to more accurately measure mercury in 
blank samples, and to a higher point (above 100 ng/L) to measure 
concentrations presently measured with other approved mercury methods. 
EPA also proposed certain criteria to ensure that this allowance would 
not compromise data quality. These criteria included: (1) A minimum of 
five, non-zero calibration points; (2) the difference between 
successive calibration points must be no greater than a factor of 10 
and no less than a factor of 2 and should be approximately evenly 
spaced on a logarithmic scale over the calibration range; (3) the 
relative standard deviation (RSD) of the calibration factors for all 
calibration points must be less than 15%; (4) the calibration factor 
for any calibration point at a concentration greater than 100 ng/L must 
be within plus or minus 15% of the average calibration factor for the 
points at or below 100 ng/L; (5) the calibration factor for any point 
less than 5 ng/L must be within plus or minus 25% of the average 
calibration factor for all points; (6) if the highest calibration point 
is increased above 100 ng/L, the lowest calibration point (ML) must be 
increased commensurately above 0.5 ng/L; and, (7) if the calibration is 
to a higher range and this Method is used for regulatory compliance, 
the ML must be less than one-third the regulatory compliance limit.
    Several commenters expressed concern regarding the proposed option 
to extend the lower end of calibration in EPA Method 1631. Commenters 
noted that in the proposed rule preceding the June 8, 1999, 
promulgation of EPA Method 1631B, EPA proposed to allow users to 
calculate lower MDLs and MLs. Based on comments, however, EPA ``removed 
the option for laboratories to calculate their own lower MDLs and MLs. 
* * *'' 64 FR 30420 (June 8, 1999). In support, EPA stated its belief 
that ``this will avoid confusion and preclude lower MDLs and MLs from 
being used for NPDES permitting or regulatory compliance 
determinations.'' Commenters stated that authorization for Method users 
to calibrate instruments to below the Method ML would result in 
regulatory uncertainty. For these reasons and in response to comments, 
EPA has clarified this provision in EPA Method 1631E by stating that, 
for the purpose of measuring the level of mercury in blank samples 
only, calibration may be extended to a lower level.
    One commenter on the proposed rule expressed concern that allowing 
extension of the high end of the calibration range could jeopardize 
low-level compliance determinations by increasing the potential for 
bias resulting from cross contamination or carryover. The commenter 
pointed out that EPA acknowledged this increased risk by proposing a 
new method section that specified a carryover test (see Proposed Rule, 
Section IV.A.7). This commenter believes that bubbler blank and method 
blank analyses are insufficient to identify and control contamination 
if calibration is extended to levels greater than 100 ng/L. EPA 
proposed to add a carryover test to Method 1631 in response to comments 
from stakeholders who requested an allowance for extension of the 
method calibration range, but were concerned about potential 
contamination that could result from extension of the upper end of 
calibration. EPA believes that the carryover test, the requirements 
associated with blank analyses, and the calibration criteria included 
in Method 1631, Revision E are sufficient to prevent effects that could 
result from cross contamination or carryover. For this reason, and in 
response to additional comments, EPA has included an allowance for 
extension of the upper end of the calibration range in EPA Method 1631, 
Revision E.
    Three additional commenters supported extension of the upper end of 
the calibration range. These commenters believe the carryover test and 
ongoing blank determinations will ensure the analytical system remains 
sufficiently clean or that carryover will be detected should it occur. 
The commenters stated, however, that the corresponding criterion that 
the lowest calibration point must be raised commensurately when the 
upper end of calibration is raised is inappropriate. Commenters stated 
further that this criterion is unnecessary, particularly if an 
analytical system is demonstrated to be sufficiently linear and clean 
as specified by QC requirements included in the Method. Commenters 
added that commensurate raising of the lower end of calibration is 
unnecessary, particularly if two of the additional proposed 
corresponding criteria for extended calibration are met (i.e., the 
calibration factor (CF) for any calibration point at a concentration 
greater than 100 ng/L must be within plus or minus 15 percent of the 
average CF for the points at or below 100 ng/L and the CF for any point 
less than 5 ng/L must be within plus or minus 25 percent of the average 
CF for all points). EPA agrees that commensurate raising of the lower 
end of calibration is unnecessary, provided the remaining calibration 
criteria are met. EPA also points out that (1) there is no similar 
restriction in other methods; (2) the carryover test included in 
Section 4.3.8.1 of Method 1631, Revision E will allow a laboratory to 
determine the level at which Hg will be carried into a succeeding 
sample or blank; (3) the extensive requirements for blanks will detect 
contamination; and (4) a laboratory can run a blank before each sample, 
if desired, to demonstrate that a preceding sample did not carry Hg 
into the next sample. For these reasons, EPA is not including the 
proposed requirement for increasing the low end of the calibration 
range when the upper end is increased in today's rule.
    Following review of these comments, EPA has determined that 
allowing Method users to raise the Method calibration range, provided 
the performance criteria specified in Section 10.4 of the Method are 
met, will increase method flexibility without compromising data 
quality. Such an allowance is consistent with EPA protocol for approval 
of new methods and with the International Union of Pure and Applied 
Chemists (IUPAC) guidelines for calibration. EPA agrees with most 
commenters and believes that Method 1631 contains QC requirements that 
are sufficient to detect and preclude carryover from samples or 
standards containing high levels of mercury (i.e., greater than 100 ng/
L). Additionally, EPA agrees that the criteria included in Section 10.4 
of the Method is sufficient to ensure data quality without the 
requirement to raise the lower end of calibration if an extended upper 
end of calibration is used. For these reasons, EPA has removed the 
requirement to commensurately raise the low end of the calibration 
range when the upper end is raised from Section 10.4 of Method 1631E 
and is approving the provision to allow extension of the upper end of 
the calibration range. EPA also agrees with most commenters that the 
proposed procedure for identifying and controlling carryover will 
assist Method users, and is promulgating the procedures in Section 
4.3.8.1 (see Section V.I. below).

F. Acceptance Criteria Associated With Blank Samples

    EPA received several comments regarding Method 1631 QC acceptance

[[Page 65883]]

criteria associated with the analysis of blank samples. Numerous 
commenters stated that an acceptance criterion stipulated as less than 
the Method MDL (<0.2 ng/L) is inappropriate. Commenters note that 
measurements below the minimum level of quantitation (i.e., the lowest 
calibration point) of an analytical method are inherently problematic 
and will result in failures attributable to random variation alone. 
Commenters also state that such a criterion is inappropriate because an 
MDL of 0.2 ng/L is not required to meet performance specifications in 
the Method. These commenters point out that Section 9.2.1 of EPA Method 
1631 states that an MDL less than or equal to 0.2 ng/L or one-third the 
regulatory compliance limit, whichever is greater, is acceptable. 
Commenters note further that if a compliance level were 4 ng/L, an MDL 
determination of 1.3 ng/L would be sufficient. In such a case, 
monitoring levels of mercury in blanks against a criterion of 0.2 ng/L 
would be inconsistent.
    Except for those criteria associated with calibration and method 
blank analyses, the QC acceptance criteria for blank samples included 
in EPA Method 1631 are identical to those originally proposed in May 
1998. EPA received, reviewed, and responded to numerous comments prior 
to promulgation of EPA Method 1631B in June of 1998. Since 
promulgation, use of EPA Method 1631 has increased significantly, as 
has the ability to meet Method QC acceptance criteria. For this reason, 
EPA did not include revisions to these acceptance criteria in the 
October 2001 proposed rule, and is not promulgating such revisions in 
today's final rule. In response to comments on the October 2001 
proposed rule, however, EPA is clarifying that the QC acceptance 
criteria for blank samples may be adjusted (i.e., raised) to support 
measurements at the compliance level (see EPA Method 1631E, Note to 
Section 9.1.2.1). For example, if the compliance level is 4 ng/L, an 
appropriate MDL would be 1.3 ng/L, the corresponding lowest calibration 
standard would be at the ML of 4 ng/L, and appropriate QC acceptance 
criteria for blank samples would be 1.3 ng/L (bubbler and reagent 
blanks) or 4 ng/L (method, field, and bottle blanks).

G. Flow-Injection Systems

    Commenters were supportive of EPA's proposed revision to 
incorporate automated flow-injection systems into EPA Method 1631. 
Commenters stated that, without EPA's acknowledgment that these systems 
are in use, implementation of such systems could be curtailed.
1. Calibration or System Blanks
    EPA Method 1631, Revision C included bubbler blanks to establish a 
background for the bubbler system (i.e., bubbler, traps, and cold-vapor 
atomic fluorescence detector). Bubbler blanks, however, are not 
appropriate for flow-injection systems. Hence, EPA proposed a 
requirement for analysis of calibration blanks when using flow-
injection systems. The proposed QC acceptance criteria and application 
requirements for the calibration blanks were identical to the existing 
QC acceptance criteria and application requirements for the bubbler 
blanks (i.e., the mean result of bubbler or calibration blanks is 
subtracted from results of calibration standards and samples and must 
be < 0.25 ng/L).
    Since proposal, EPA has determined that the term ``system'' blank 
is more appropriate for the blank samples associated with flow-
injection systems because these blank samples are used to assess 
contamination during calibration and during analysis of analytical 
batches. Therefore, EPA has replaced the proposed term ``calibration 
blank'' with ``system blank'' throughout Method 1631E.
    Numerous commenters strongly objected to the requirements 
associated with the system blanks that EPA proposed to accompany flow-
injection systems. Commenters stated that bubbler blanks and 
calibration (i.e., system) blanks are not identical in either 
composition or purpose, and emphasized that it would be inappropriate 
and impractical to treat these samples as identical. Commenters noted 
that, unlike bubbler blanks which analyze previously-purged water to 
measure the level of mercury remaining in the bubbler system, system 
blanks measure residual mercury in reagent water as well as mercury in 
the reagents used in the calibration standards and samples. Commenters 
added that for this reason, the proposed system blank criteria for 
flow-injection systems are at least twice as restrictive as those 
placed on the use of bubbler systems.
    In response to comments and upon further review of automated flow-
injection systems, EPA has revised the proposed requirements associated 
with system blanks. EPA recognizes that flow injection systems require 
that reagents are added to all samples including the calibration 
standards, and has included a criterion in Section 9.4.2 of EPA Method 
1631E that system blanks containing levels of mercury equal to or 
greater than 0.5 ng/L demonstrate that the system is out of control.
2. Terminology
    Two commenters on the proposed rule stated that EPA should revise 
the term used for these systems from ``Automated Flow-Injection'' to 
``Continuous Flow'' throughout EPA Method 1631. Although EPA agrees 
with these commenters that ``Continuous Flow'' is descriptive of the 
flow-injection systems used for determination of mercury in EPA Method 
1631, it is a generic term that includes other systems such as 
sequential injection, sequential flow, and bead injection systems. EPA 
believes that the system described in EPA Method 1631 is consistent 
with the definition of a flow injection system, and has retained the 
proposed ``flow-injection'' terminology throughout EPA Method 1631E.

H. Sample Containers

    Twelve commenters submitted comments regarding the proposed 
requirement to use either glass or fluoropolymer containers for 
collection of samples for measurement of mercury using EPA Method 1631. 
Commenters generally emphasized support for the performance-based 
nature of sample container selection to preclude unnecessary expense 
and allow for development of future materials. However, most commenters 
also expressed preference for fluoropolymer, glass, or fluoropolymer-
lined glass containers for sample collection and preparation, 
particularly because of the possibility for some forms of mercury to 
move in or out of containers composed of other materials.
    Four commenters on the proposed rule requested that EPA Method 1631 
be revised to allow collection of samples in high density polyethylene 
(HDPE) containers if the samples are shipped to the laboratory for 
preservation and transferred to fluoropolymer containers within 48 
hours. These commenters submitted identical data comparing summary 
results of samples collected using fluoropolymer sample bottles to 
samples collected using HDPE sample bottles to support this request. 
These data are included in Section V.E.1.10 of the Rulemaking Record. 
EPA has reviewed these data, and notes that although the results of the 
composite samples collected using either container type do not 
demonstrate a significant trend in mercury increase or loss, the 
results of the grab samples indicate a consistent increase in mercury 
concentration, ranging from 15 to 240 percent, in samples collected 
using HDPE containers.

[[Page 65884]]

    EPA recognizes the concern that some forms of mercury can move in 
or out of containers composed of materials other than fluoropolymer or 
glass, and believes this concern is emphasized by commenters requesting 
that samples collected using HDPE containers be allowed only if the 
samples are transferred to fluoropolymer containers within 48 hours. In 
response to comments, and in recognition of current Method 
implementation practices, EPA is including a requirement in EPA Method 
1631E that only fluoropolymer or glass containers be used for 
collection of samples to avoid artificial increases in mercury levels 
prior to measurement.

I. Carryover

    EPA proposed to include a carryover test in Method 1631 to 
determine the concentration at which greater than 0.2 ng/L mercury 
would be carried into the subsequent sample (see draft EPA Method 
1631D, Section 4.3.8.1). EPA also proposed to require that each time a 
laboratory analyzes a sample containing the concentration of mercury 
determined to result in 0.2 ng/L carryover, the laboratory must run a 
bubbler or calibration blank to ensure carryover does not affect the 
results of the analysis of the subsequent samples.
    Commenters generally supported incorporation of a carryover test to 
identify and control contamination from carryover that can result from 
analysis of samples containing high levels of mercury. Commenters also 
supported the proposed requirement for analysis of a blank sample 
following a sample containing a high level of mercury to demonstrate 
that the analytical system is clean. Several commenters, however, noted 
that the proposed standard for determining carryover (i.e., the level 
at which the analytical system will carry greater than 0.2 ng/L of Hg 
into a succeeding bubbler or calibration blank) is inappropriate 
because measurements below the ML of 0.5 ng/L are unreliable.
    EPA has reviewed these comments and agrees with commenters' 
concerns regarding this performance standard. EPA recognizes that the 
carryover test is designed to target samples containing levels of 
mercury that could cause carryover, and believes that a performance 
standard of 0.5 ng/L is appropriate for the purposes of this test. EPA 
also believes, however, that in order to ensure data quality at the low 
levels of detection achievable by EPA Method 1631, levels of mercury no 
greater than 0.2 ng/L should be permitted to be carried over into 
succeeding samples. For this reason, EPA is requiring that a bubbler 
blank or system blank be analyzed following a sample containing a level 
of mercury that is one-half or greater than the level identified in the 
carryover test. Specifically, EPA is requiring that when a sample is 
analyzed that contains one-half or greater of the level of mercury that 
has been determined to result in 0.5 ng/L carryover, a blank must be 
analyzed to demonstrate no carryover at the 0.2 ng/L level (see Section 
4.3.8.1 of EPA Method 1631E). For example, if the carryover test 
determines that samples containing 150 ng/L result in carryover greater 
than 0.5 ng/L, then the laboratory must analyze a blank sample 
following analysis of any sample containing more than 75 ng/L mercury.
    EPA received additional comments presenting other concerns related 
to the carryover test. Commenters noted that it is unnecessary to 
require analysts to order samples from the lowest to the highest 
concentration. Commenters stated that analysts will define the order of 
samples according to information made available to them, and that there 
are other factors besides mercury concentration that are important in 
determining the order of samples. Commenters also noted that EPA should 
clarify that blanks should be run on the same bubbler used to run the 
high-concentration sample and that the requirements for the carryover 
test were not included in procedures for implementation of flow 
injection systems. EPA acknowledges that analysts often are not aware 
of the concentration levels of mercury contained in samples and that 
analysts may wish to order samples from least complex matrix to most 
complex matrix (e.g., ambient water to influent). For this reason, EPA 
has removed the requirement, and is instead recommending that samples 
known or suspected to contain the lowest concentration of mercury 
should be analyzed first followed by samples containing higher levels. 
EPA also has clarified that a bubbler blank should be analyzed using 
the same bubbler as that used to analyze the high-concentration sample 
and has added Section 11.2.2.3 to EPA Method 1631E to clarify that the 
carryover test and associated blank analysis are required.

J. Other Technical Details

    Several commenters requested revisions and clarifications to the 
Method that were already addressed in the Guidance or were beyond the 
scope of the proposed rule. Specifically, EPA received comments 
requesting the inclusion of all QC acceptance criteria into a single 
table in Method 1631; clarification of site-specific frequency 
requirements associated with MS/MSD samples; additional recommendations 
for sample filtration, clean techniques, and sample handling 
procedures; and approval of EPA Method 245.7: Mercury in Water by Cold 
Vapor Atomic Fluorescence Spectrometry.
    Following promulgation of today's rule, the Agency plans to revise 
the Guidance to reflect today's final rule and to incorporate further 
clarification of Method procedures. EPA also has completed a study to 
validate Method 245.7 in multiple laboratories and is planning to 
continue efforts towards approval of this additional test procedure.
    EPA reviewed all the additional recommendations and comments and 
has provided responses to each in the Comment Response Document.

VI. Administrative Requirements

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735 (October 4, 1993)), the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to Office of Management and Budget (OMB) review 
and the requirements of the Executive Order. The Executive 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.
    It has been determined that this rule is not a ``significant 
regulatory action'' under the terms of Executive Order 12866 and is 
therefore not subject to OMB review.

B. Regulatory Flexibility Act (RFA), as Amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 U.S.C. 601 et 
seq.

    The RFA generally requires an agency to prepare a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedure Act

[[Page 65885]]

or any other statute unless the agency certifies that the rule will not 
have a significant economic impact on a substantial number of small 
entities. Small entities include small businesses, small organizations, 
and small governmental jurisdictions.
    For purposes of assessing the impacts of today's rule on small 
entities, small entity is defined as: (1) A small business as defined 
by the U.S. Small Business Administration definitions at 13 CFR 
121.201; (2) a small governmental jurisdiction that is a government of 
a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for-profit enterprise which is independently owned and operated 
and is not dominant in its field.
    After considering the economic impacts of today's rule on small 
entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. Today's rule 
promulgates a revised version of an already approved EPA Method to 
improve and clarify method procedures. Today's rule also promulgates an 
amendment to Table II at 40 CFR 136.3(e) to provide consistency with 
previously approved requirements in EPA Method 1631 and with method 
revisions promulgated today for collection, preservation, and storage 
of samples for determination of mercury using Method 1631.
    Overall, the costs of these revisions are minimal. While some of 
the revisions may increase cost (e.g., quality control requirements), 
other revisions will offset any increases and provide flexibility to 
lower the overall analytical costs (e.g., use of new, less expensive 
equipment). Many of the laboratories that analyze for mercury are 
already implementing the additional requirements, further minimizing 
any potential cost increases. EPA estimates that any costs associated 
with the additional requirements will be alleviated or eliminated by 
the additional flexibility. Therefore, EPA believes that this rule will 
not have a significant economic impact on a substantial number of small 
entities.

C. 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, Tribal, and local 
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, Tribal, and local 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 of why that 
alternative was not adopted.
    Before EPA establishes any regulatory requirements that may 
significantly or uniquely affect small governments, including Tribal 
governments, it must have developed under section 203 of the UMRA a 
small government agency plan. The plan must provide for the 
notification of 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 rule contains no Federal mandate (under the regulatory 
provisions of Title II of the UMRA) for State, Tribal, and local 
governments or the private sector in any one year. This rule imposes no 
enforceable duty on any State, local or Tribal governments or the 
private sector. This rule promulgates revisions to a previously 
approved method for measuring mercury in wastewater. This rule also 
revises Table II at 40 CFR 136.3(e) to clarify requirements for sample 
collection, preservation, and storage, and to make these requirements 
consistent with previously approved requirements in EPA Method 1631 and 
with today's promulgated method revisions. Thus, today's rule is not 
subject to sections 202 and 205 of the UMRA. For the same reasons, EPA 
has also determined that this rule contains no regulatory requirements 
that might significantly or uniquely affect small governments. Thus, 
today's rule also is not subject to the requirements of section 203 of 
the UMRA.

D. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 
It does not impose any information collection, reporting or record 
keeping requirements. This action revises a currently approved test 
method for use in water monitoring programs but does not add additional 
burden nor specifically require the use of the test method. Burden 
means the total time, effort, or financial resources expended by 
persons to generate, maintain, retain or disclose or provide 
information to or for a Federal agency. This includes the time needed 
to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previoulsy applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    An Agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB numbers for EPA's 
regulations are listed in 40 CFR Part 9 and 48 CFR Chapter 15.

E. 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., material 
specifications, test methods, sampling procedures, business practices) 
that are developed or adopted by voluntary consensus standard bodies 
(VCSBs). 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. However, EPA

[[Page 65886]]

identified no such standards for the measurement of mercury at water 
quality criteria levels, and none were brought to our attention in 
comments. Therefore, EPA has decided to promulgate EPA Method 1631, 
Revision E: Mercury in Water by Oxidation, Purge and Trap, and Cold 
Vapor Atomic Fluorescence Spectrometry.

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

    Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any 
rule that: (1) is determined to be ``economically significant'' as 
defined under Executive Order 12866, and (2) concerns an environmental 
health or safety risk that EPA has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, the Agency must evaluate the environmental health or 
safety effects of the planned rule on children, and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency. This rule is 
not subject to Executive Order 13045 because it is neither 
``economically significant'' as defined in Executive Order 12866, nor 
does it concern an environmental health or safety risk that EPA has 
reason to believe may have a disproportionate effect on children.

G. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    This final rule does not have federalism implications. It will not 
have substantial direct effects on the States, on the relationship 
between the national government and the States, or on the distribution 
of power and responsibilities among the various levels of government, 
as specified in Executive Order 13132. Today's rule promulgates EPA 
Method 1631, Revision E to replace an already approved version of the 
method for measuring mercury at low levels for compliance monitoring 
under the Clean Water Act and provide additional flexibility for use of 
currently available technologies. The costs of this rule for State and 
local governments are minimal. Thus, Executive Order 13132 does not 
apply to this rule.

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

    Executive Order 13175, titled ``Consultation and Coordination With 
Indian Tribal Governments'' (65 FR 67249, November 9, 2000), requires 
EPA to develop an accountable process to ensure ``meaningful and timely 
input by Tribal officials in the development of regulatory policies 
that have Tribal implications. ``Policies that have Tribal 
implications'' is defined in the Executive Order to include regulations 
that have ``substantial direct effects on one or more Indian Tribes, on 
the relationship between the Federal government and the Indian Tribes 
or on the distribution of power and responsibilities between the 
Federal government and Indian Tribes.''
    This final rule does not have Tribal implications. It will not have 
substantial direct effects on Tribal governments, on the relationship 
between the Federal government and Indian Tribes, or on the 
distribution of power and responsibilities between the Federal 
government and Indian Tribes, as specified in Executive Order 13175. 
Today's rule promulgates EPA Method 1631, Revision E to replace an 
already approved version of the method for measuring mercury at low 
levels for compliance monitoring under the Clean Water Act, and provide 
additional flexibility for use of currently available technologies. The 
costs of this rule for Tribal governments are minimal. Thus, Executive 
Order 13175 does not apply to this rule.

I. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2). This rule will be effective on November 29, 2002.

J. Executive Order 13211: Energy Effects

    This rule is not subject to Executive Order 13211, ``Actions 
Concerning Regulations That Significantly Affect Energy Supply, 
Distribution, or Use'' (66 FR 28355 (May 22, 2001)) because it is not a 
significant regulatory action under Executive Order 12866.

K. Plain Language Directive

    Executive Order 12866 directs each agency to write its rules in 
plain language. Readable regulations help the public find requirements 
quickly and understand them easily. Plain language increases 
compliance, strengthens enforcement, and decreases mistakes, 
frustration, phone calls, appeals, and distrust of government. EPA made 
every effort to write this preamble to the final rule in as clear, 
concise, and unambiguous manner as possible. Specifically, EPA used 
active voice and avoided the use of technical terms except when 
necessary. EPA solicited but received no comments on the Plain Language 
aspects of this rule.

List of Subjects in 40 CFR Part 136

    Environmental protection, Incorporation by reference, Reporting and 
recordkeeping requirements, Water pollution control.

    Dated: September 30, 2002.
Christine Todd Whitman,
Administrator.

    For the reasons set out in the preamble, title 40, chapter I of the 
Code of Federal Regulations, is amended as follows:

PART 136--GUIDELINES ESTABLISHING TEST PROCEDURES FOR THE ANALYSIS 
OF POLLUTANTS

    1. The authority citation for Part 136 continues to read as 
follows:

    Authority: Secs. 301, 304(h), 307, and 501(a), Pub. L. 95-217, 
91 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 is amended:
    a. By revising Item 35 in Table IB of paragraph (a).
    b. By revising Footnote 43 to Table IB of paragraph (a).
    c. By revising paragraph (b)(41).
    d. By revising entries 18 and 35 under the heading ``Metals'' in 
Table II of paragraph (e).


Sec.  136.3  Identification of test procedures.

* * * * *

[[Page 65887]]



                                                                      Table 1B.--List of Approved Inorganic Test Procedures
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 Reference (method number or page)
   Parameter, units and method    --------------------------------------------------------------------------------------------------------------------------------------------------------------
                                              EPA 1, 35             Standard methods [edition(s)]               ASTM                           USGS 2                          Other
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                                          * * * * * * *
35. Mercury--Total,4 mg/L:
    Cold vapor, manual or........  245.1.........................  3112 B [18th, 19th]...........  D3223-91......................  I-3462-85.....................  977.22 3
    Automated....................  245.2.........................
    Oxidation, purge and trap,     1631E 43......................
     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 samples 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 1B 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 USEPA. 2002. Method 1631, Revision E, ``Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry.'' September 2002. Office of Water, U.S. Environmental
  Protection Agency (EPA-821-R-02-019). 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.

* * * * *
    (b) * * *
    (41) USEPA. 2002. Method 1631, Revision E, ``Mercury in Water by 
Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence 
Spectrometry.'' September 2002. Office of Water, U.S. Environmental 
Protection Agency (EPA-821-R-02-019). Available from: National 
Technical Information Service, 5285 Port Royal Road, Springfield, 
Virginia 22161. Publication No. PB2002-108220. Cost: $25.50 (subject to 
change).
* * * * *
    (e) * * *

                   Table II.--Required Containers, Preservation Techniques, and Holding Times
----------------------------------------------------------------------------------------------------------------
         Parameter No./name               Container \1\        Preservation \2,3\      Maximum holding time \4\
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Metals
    18. Chromium VI \7\............  P, G..................  Cool, 4[deg]C.........  24 hours.
    35. Mercury \17\...............  P, G..................  HNO3 to pH<2..........  28 days.
    3, 5-8, 12,13, 19, 20, 22, 26,   P, G..................  do....................  6 months.
     29, 30, 32-34, 36, 37, 45, 47,
     51, 52, 58-60, 62, 63, 70-72,
     74, 75. Metals except boron,
     chromium VI and mercury \7\.
 

[[Page 65888]]

 
                                                 * * * * * * *
----------------------------------------------------------------------------------------------------------------
\1\ Polyethylene (P) or glass (G). For microbiology, plastic sample containers must be made of sterilizable
  materials (polypropylene or other autoclavable plastic), except for samples collected for trace-level mercury
  (see footnote 17).
\2\ Sample preservation should be performed immediately upon sample collection. For composite chemical samples
  each aliquot should be preserved at the time of collection. When use of an automated sampler makes it
  impossible to preserve each aliquot, then chemical samples may be preserved by maintaining at 4[deg]C until
  compositing and sample splitting is completed, except for samples collected for trace-level mercury (see
  footnote 17).
\3\ When any sample is to be shipped by common carrier or sent through the United States Mails, it must comply
  with the Department of Transportation Hazardous Materials Regulations (49 CFR part 172). The person offering
  such material for transportation is responsible for ensuring such compliance. For the preservation
  requirements of Table II, the Office of Hazardous Materials, Materials Transportation Bureau, Department of
  Transportation has determined that the Hazardous Materials Regulations do not apply to the following
  materials: Hydrochloric acid (HCl) in water solutions at concentrations of 0.04% by weight or less (pH about
  1.96 or greater); Nitric acid (HNO3) in water solutions at concentrations of 0.15% by weight or less (pH about
  1.62 or greater); Sulfuric acid (H2SO4) in water solutions at concentrations of 0.35% by weight or less (pH
  about 1.15 or greater); and Sodium hydroxide (NaOH) in water solutions at concentrations of 0.080% by weight
  or less (pH about 12.30 or less).
\4\ Samples should be analyzed as soon as possible after collection. The times listed are the maximum times that
  samples may be held before analysis and still be considered valid. (See footnote 17 for samples collected for
  trace level mercury). Samples may be held for longer periods only if the permittee, or monitoring laboratory,
  has data on file to show that for the specific types of samples under study, the analytes are stable for the
  longer time, and has received a variance from the Regional Administrator under Sec.   136.3(e). Some samples
  may not be stable for the maximum time period given in the table. A permittee, or monitoring laboratory, is
  obligated to hold the sample for a shorter time if knowledge exists to show that this is necessary to maintain
  sample stability. See Sec.   136.3(e) for details. The term ``analyze immediately'' usually means within 15
  minutes or less of sample collection.
 
 * * * * *
\7\ Samples should be filtered immediately on site before adding preservative for dissolved metals, except for
  samples collected for trace-level mercury (see footnote 17).
 
 * * * * *
\17\ Samples collected for the determination of trace level mercury (100 ng/L) using EPA Method 1631 must be
  collected in tightly-capped fluoropolymer or glass bottles and preserved with BrCl or HCl solution within 48
  hours of sample collection. The time to preservation may be extended to 28 days if a sample is oxidized in the
  sample bottle. Samples collected for dissolved trace level mercury should be filtered in the laboratory.
  However, if circumstances prevent overnight shipment, samples should be filtered in a designated clean area in
  the field in accordance with procedures given in Method 1669. Samples that have been collected for
  determination of total or dissolved trace level mercury must be analyzed within 90 days of sample collection.

[FR Doc. 02-27136 Filed 10-28-02; 8:45 am]
BILLING CODE 6560-50-P