CREDIBLE EVIDENCE RULE REVISIONS: RESPONSE TO COMMENTS
Office of Enforcement and Compliance Assurance
U.S. Environmental Protection Agency
February 1997
February 12, 1997
CREDIBLE EVIDENCE RULE REVISIONS: RESPONSE TO COMMENTS
TABLE OF CONTENTS
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . .1
SECTION 1: Statutory Authority for the CE Revisions . . . . . .3
1.1 Comments in Response to Original EM Proposal. . .3
1.2 Comments in Response to March 21, 1996 Policy Paper6
SECTION 2: Definition of "Credible Evidence" and Its Use for Determining Compliance9
2.1 Comments in Response to Original EM Proposal. . .9
2.1.1 General Appropriateness of Using Enhanced Monitoring Data for
Compliance Determinations . . . . . . .9
2.1.2 Use of Opacity Data to Determine Compliance with
Particulate Matter Standards . . 11
2.1.3 Use of Other Data to Determine Compliance11
2.1.4 Clarifications of "Other Credible Evidence" Provisions13
2.1.5 Use of Non-Enhanced Monitoring Data 14
2.1.6 Necessity for a Rulemaking to Establish Compliance Test
Methods. . . . . . . . . . . . . 15
2.2 Comments in Response to March 21, 1996 Policy Paper 18
SECTION 3: CE Revisions Language (Parts 51, 52, 60 and 61) 24
3.1 Comments in Response to Original EM Proposal. . 24
3.1.1 Enhanced Monitoring Data as Presumptively Credible Evidence24
3.1.2 Miscellaneous Issues . . . . . . . . . . . 25
SECTION 4: Stringency of Underlying Requirements. . . . . . . 27
4.1 Comments in Response to Original EM Proposal. . 27
4.1.1 Stringency of Underlying Requirements - Defining Compliance27
4.1.2 Stringency of Underlying Requirements - Averaging Time Concerns55
4.1.2.1 Use of Reference Test Method Sampling Times as
Averaging Times . . . . . . . . . . . 57
4.1.2.2 Gap-filling Authority to Specify Averaging Times64
4.1.2.3 Need for Short Term Averaging Periods 66
4.1.3 Means of Addressing Stringency Concerns. . 66
4.1.4 Excused Excess Emissions . . . . . . . . . 67
4.2 Comments in Response to March 21, 1996 Policy Paper 68
SECTION 5: Enforcement Exposure . . . . . . . . . . . . . . . 82
5.1 Comments in Response to May 21, 1996 Policy Paper 82
SECTION 6: Necessity for the Use of "Any Credible Evidence" . 86
6.1 Comments in Response to May 21, 1996 Policy Paper 86
SECTION 7: Increased Burden Associated with the Use of "Any Credible Evidence"88
7.1 Comments in Response to March 21, 1996 Policy Paper 88
SECTION 8: Regulatory Process . . . . . . . . . . . . . . . . 90
8.1 Comments in Response to March 21, 1996 Policy Paper 90
SECTION 9: Voluntary Data Collection. . . . . . . . . . . . . 94
9.1 Comments in Response to March 21, 1996 Policy Paper 94
SECTION 10: Miscellaneous Comments. . . . . . . . . . . . . . 95
10.1 Comments in Response to March 21, 1996 Policy Paper 95
SECTION 11: Comments Made in Recent Letter to Browner and Proposed Responses100
February 12, 1997
INTRODUCTION
The conforming amendments to parts 51, 52, 60 and 61 to clarify that any credible evidence may
be used to establish compliance or noncompliance with applicable requirements of the Act
(referred to as the "CE revisions" or "CE" throughout this document) are being promulgated
under the authority of applicable provisions in section 113(a) of the Clean Air Act (the "Act").
Additional authority is provided by section 113(e). These CE revisions were originally proposed
in conjunction with enhanced monitoring requirements under part 64 designed to fulfill
requirements in section 114(a) of the Act. The EPA proposed the part 64 requirements and the
CE revisions together on October 22, 1993, at 58 FR 54648. The proposal announced the
opportunity for written public comment until December 20, 1993, which date was subsequently
extended until January 31, 1994. The proposal also provided notice of a public hearing, which
was conducted in Washington, D.C. on November 19, 1993. In the fall of 1994, EPA held a
series of informational meetings with interested parties affected by the rule. The public
comment
period then was reopened from December 28, 1994 until February 3, 1995 to take additional
comment on a limited number of specific issues. In addition, the Agency held an additional
stakeholder meeting. In response to the reopened public comment period, EPA received over
200
additional comment letters.
In April 1995, EPA announced that it was suspending development of the enhanced monitoring
rule while it developed a compliance assurance monitoring (CAM) approach to serve the same
statutory goals. In a September 1995 public draft of the CAM approach, EPA stated that it
would hold further discussions with stakeholders before it proceeded to finalize the CE revisions.
On March 8, 1996, EPA announced that a public meeting on credible evidence issues would be
held on April 2, 1996. To focus the meeting's discussion, EPA released a paper on March 21,
1996, entitled "The Use of Information Other Than Reference Test Results for Determining
Compliance With the Clean Air Act" (sometimes referred to as the "Credible Evidence White
Paper"). EPA distributed this paper by electronic bulletin board to the same stakeholders who
were involved in the enhanced monitoring and CAM rulemakings, further distributed it to
various
other interested parties, and made it generally available to the public.
The public meeting was held on April 2, 1996, at EPA Headquarters in Washington, D.C., where
twenty-three organizations and individuals presented oral statements and written comments. At
the meeting, EPA announced that, although the rulemaking docket would not formally be
re-opened, additional written comments would be accepted for at least another 30 days.
Moreover,
EPA stated that it would meet with any interested parties to discuss the credible evidence rules.
As a result, many additional written comments on the CE revisions have been received, and
numerous additional EPA/stakeholder meetings have been held. (See Docket A-91-52, Items
IV-D-774 through IV-D-843, IV-F-4, and various items in Section IV-E of the docket.) Further,
on
August 2, 1996, EPA made available to the public a revised draft CAM approach via electronic
bulletin board (for information call 919-541-5384); the draft is also available in the Air Docket.
Complete transcripts of the public hearings and the full text of each comment letter, along with
supporting information used in developing the regulations, are contained in Docket No. A-91-52.
This docket is available for public inspection and copying between 8:00 a.m. and 5:30 p.m.
Monday through Friday, excluding government holidays, at Room M-1500, Waterside Mall, 401
M Street S.W., Washington, D.C. Note that Section VI of the docket has been reserved for
information related to the CAM rulemaking. Comments placed into that portion of the docket
have been received on the draft CAM rulemaking and do not constitute part of the record for the
CE revisions.
This document summarizes and responds to the written and oral comments submitted at the
November 19, 1993 and April 1996 public hearings, as well as the comment letters received
during the original public comment period, the reopened comment period, and subsequent to the
April 2, 1996 public hearing. The reader should note that many of the most significant
comments
are responded to in the preamble to the final rule. The preamble discussion is the formal
exposition of Agency policy and interpretation. The responses in this document cross-reference
the appropriate discussion in the preamble where appropriate. Finally, wherever a commenter
may have incorporated the comments of others by reference, those commenters are incorporated
by reference into the list of commenters under any particular issue in which the primary
commenter is listed in this document.
This document includes many citations to other authorities outside of the CE revisions. These
citations are generally not followed by their origin, such as "of the Clean Air Act." Rather, the
reader can recognize the origins of the sections by their nature: sections of existing EPA
regulations are preceded by 40 CFR, except in the case of 40 CFR part 70, which is frequently
cited only as "part 70," and sections therein cited as, e.g., " 70.2." Sections of the Act are
referenced by a three digit number, such as "114" or "504." This document also often refers to
"State" or "permitting authority." The reader should assume that where the document refers to a
"State," the reference also includes local air pollution agencies, Indian tribes, and territories of
the
United States to the extent they are or will be the permitting authority for their area, or have been
or will be delegated permitting responsibilities under the Act. In addition, the term "permitting
authority" would also include EPA to the extent EPA is the permitting authority of record.
SECTION 1: Statutory Authority for the CE Revisions
1.1 Comments in Response to Original EM Proposal
SUMMARY: A number of commenters objected to using CE to determine compliance, arguing
that section 113(e) allows such evidence to be used to assess penalties only, and not to determine
whether a violation has occurred.
Numerous commenters cited the language and context of section 113(e) to support their
argument. Many argued that section 113(e)(1) merely provides that credible evidence other than
test methods may be considered to determine the duration of a violation that has already been
proven by use of a test method. One commenter suggested that the statutory reference to CE had
to be read in pari materia with the other items listed in that paragraph; all of which are relevant
solely to penalty assessment. Another commenter stated that although some penalty factors and
elements of liability may potentially overlap, the same evidence is not admissible for either
purpose. One commenter also stated that section 113(e)(2), which creates a presumption of
noncompliance after proof of a violation, is consistent with the use of the evidence for penalty
assessment only. Other commenters cited sections 113(a) and 113(d)(1) to show that where
Congress wanted to allow EPA to proceed on the basis of "any available information," it clearly
stated that intention -- unlike section 113(e)(1).
Commenters argued that EPA's reliance on legislative history to interpret "any credible evidence"
was improper under the ruling in Chevron, U.S.A. v. Natural Resources Defense Council, Inc.,
467 U.S. 837 (1984) [cited as Chevron v. NRDC in remainder of this document], which directs
the Agency to not rely on legislative history where statutory language is clear on its face as it
allegedly is in section 113(e). If legislative history is to be considered, several commenters
stated
that the legislative history of section 113(e) actually supports the limited interpretation of section
113(e) as merely applying to penalty assessments. Some commenters also argued that the
legislative history used by EPA was insufficient to support EPA's position that section 113(e)(1)
may be used to prove a violation. Finally, commenters criticized EPA's reliance on the ruling in
United States v. Kaiser Steel Corp., No. 82-2623-IH (C.D. Cal. Jan. 17, 1984) [cited as Kaiser
Steel in remainder of this document] to support its interpretation because that ruling was an
unpublished opinion cited once in a congressional report; a much clearer statement of intent than
this sole reference would be required to overturn decades of EPA practice and case law.
Commenters also looked to EPA's past practice as to what evidence may be used to determine
compliance. Some industry commenters noted that EPA has always viewed the test method as
an
integral part of an emission standard and proof of a violation. One commenter noted that
reference methods are important because they provide a clear, consistent gauge of compliance
that have been scientifically verified and developed through formal notice and comment
rulemaking. The same commenter added that to reverse this practice, a much clearer
congressional directive was required. The commenter argued that since regulatory practice and
case law have required the use of test methods to determine compliance for the past twenty years,
there is no basis for the statements in the preamble to the proposed rule that the amended section
113(e) revises this well-established practice.
RESPONSE: The EPA believes that the commenters have misunderstood the Agency's authority
for revising existing regulations and calling for revisions to State Implementation Plans (SIPs).
These rule revisions and SIP calls are based on EPA's existing authority prior to the 1990
Amendments, which alone would authorize these rules, as well as its amplified authority
following
the 1990 Amendments. Congress, in several places in the 1990 Amendments, expanded the
obligation for sources to demonstrate compliance and the authority of EPA and citizens to take
enforcement action against violations of requirements under the Act. One significant provision
of
the 1990 Amendments in this regard is the revised section 113(e), but EPA is not relying solely
on
this revised section as the basis for changing its past practices. Section 113(a) is also a primary
source of authority for these revisions. See below, and Section III.C. of the preamble to the final
rule, for further discussion of EPA's basis for asserting that section 113(e)(1) authorizes the use
of credible evidence for both establishing liability and assessing penalties.
It should also be emphasized that EPA is continuing to rely on the reference test method as the
lodestar for determining what evidence is credible, and thus such tests continue to be an integral
part of the emission standard.
EPA explains its understanding of the legislative history in Section III.C.5. of the preamble. In
further response, EPA notes that it is not relying solely on Congress' reference to the Kaiser Steel
decision to justify this rulemaking. Nonetheless, EPA believes that the Senate Report's reference
to Kaiser Steel is a clear signal of Congress' displeasure with judicial decisions that limited
EPA's
ability to use credible evidence other than data from reference tests. Additionally, contrary to
assertions by the commenters, EPA does not believe that either case law or past EPA practice
limit EPA from adopting these credible evidence revisions absent a major change in the Act. As
explained in the preamble in Section III.C.3. and elsewhere in this Response to Comments (See
Section 4.2), the case law does not hold that the statute mandates the use of exclusive reference
tests. Further, EPA practice has not been based on the theory that the statute demands such an
exclusive reference method approach. EPA's practice has been based on its regulations, and
today's rulemaking amends those regulations in a manner consistent with the longstanding
authority in section 113(a) that permits EPA to prosecute a violation on "any information."
Specifically as to section 113(e), EPA disagrees with those commenters who argued that the
Agency has taken a statutory provision intended by Congress to apply only to penalty
determinations and "bootstrapped" it inappropriately to apply to the issue of what evidence EPA
can use to prove the existence and duration of a violation. As an initial matter, as discussed
above, EPA believes that it has plenary statutory authority even without section 113(e) to remove
any regulatory restrictions on the appropriate evidence for proving violations. Section 113(e),
along with its legislative history, provides a clear example in the 1990 Amendments of
congressional intent to broaden the ability of EPA to take enforcement action under the Act by
any appropriate means, consistent with the general enforcement authority in section 113(a). EPA
is responding to the 1990 Amendments by removing regulatory restrictions on its ability to prove
violations.
Moreover, EPA takes a different view of the meaning of section 113(e). Section 113(e) states
that the Administrator or the court, "in determining the amount of any penalty to be assessed,"
shall take into consideration (among other things) "the duration of a violation as established by
any credible evidence (including evidence other than the applicable test method)". This statutory
provision is clear on its face that any credible evidence, including evidence other than from the
applicable test method, may now be used for such purpose. Moreover, under the Act (for
example, sections 113(b) and 113(e)(2)), penalties are assessed for each day of each violation.
Consequently, the Agency cannot collect a penalty on any particular day which falls during the
"duration of a violation" unless it also proves that a violation occurred on that day. Proof of the
violation is thus inextricably linked to proof of the duration of the violation. EPA, therefore,
believes that section 113(e) allows EPA to use any credible evidence, not only for penalty
purposes, but also to establish the existence of violations.
The argument of some commenters that subsection 113(e)(1) applies only to penalty
determinations because it is contained in a section entitled "Penalty Assessment Criteria," is
particularly unpersuasive in light of section 113(e)(2). Section 113(e)(2), while authorizing EPA
to assess daily penalties, primarily concerns the purely evidentiary matters of the plaintiffs' prima
facie case for proving a continuing or recurring violation and the burden of proof. Both sections
113(e)(1) and (2) provide instruction to courts and EPA as to how EPA or a citizen may prove
violations, consistent with general enforcement authority under section 113(a).
EPA notes that some commenters criticized statements in the preamble to the proposed rule that
applied section 113(e) both to the establishment of an initial violation, as well as the
determination
of its duration. These arguments fail to take full account of other interpretations. For example,
one possible reading of section 113(e)(1) is that the reference to "other credible evidence" is tied
to the "duration" of the violation. Another possible reading is that "other credible evidence"
modifies the word "violation" rather than the word "duration," reflecting a choice by Congress in
the context of amending section 113(e)(1) to clarify what evidence may be used to establish the
existence of a violation. Further, even if "other credible evidence" were viewed as modifying
"duration" rather than "violation," the common meaning of the word "duration" is "the time
during which something exists or lasts." Webster's Collegiate Dictionary (10th ed., 1993)
(emphasis added). A violation exists and lasts from its beginning to its end, so the duration of a
violation includes each and every day that the violation occurs including the initial day of
violation.
Other provisions of the 1990 Amendments also demonstrate congressional intent that EPA and
sources may rely on any credible evidence in establishing compliance or violations under the
Act.
Section 114(a)(3), requiring enhanced monitoring and compliance certifications, was added as
part of the 1990 Amendments and it, too, supports EPA's position that compliance and violations
may be determined on the basis of any credible evidence. Much of the monitoring, reporting and
recordkeeping performed under NSPS or NESHAP has previously been relied on only as an
indicator of compliance, and EPA typically has determined the compliance status of sources by
conducting on-site inspections, or by issuing source-specific investigatory letters requiring the
collection and submission of emission data. The Senate committee report on S. 1630 stated
explicitly that section 114(a)(3) would change this approach to enforcement, stating that
"compliance certifications and emission data submitted pursuant to this [section 114(a)(3)]
authority will facilitate enforcement, due in part to the fact that such data and certifications can
be
used as evidence." S. Rep. 228, 101st Cong., 1st Sess., at 368 (1989).
Similarly, section 504(b), which was added as part of the 1990 Amendments and is part of the
title
V operating permits program, authorizes the Administrator to prescribe the "procedure and
methods for determining compliance ... but continuous emissions monitoring need not be
required
if alternative methods are available that provide sufficiently reliable and timely information for
determining compliance." This provision contemplates establishment of additional means of
determining compliance and provides further indication that Congress intended for EPA to
expand
the types of evidence upon which it can determine compliance and pursue appropriate
enforcement.
COMMENTERS:
American Automobile Manufacturers Association (IV-D-538); Chemical Manufacturers
Association (IV-D-301); Clean Air Implementation Project (IV-D-242); Coalition for Clean Air
Implementation (IV-D-304); Eastman Chemical Company (IV-D-347); Fertilizer Institute, The
(IV-D-251); Monsanto Company (IV-D-273); National Environmental Development Association
(IV-D-334); Ohio Edison (IV-D-266); Ohio Electric Utilities Institute (IV-D-323);
Pharmaceutical Manufacturers Association (IV-D-367); Shell Oil Company (IV-D-280); Texaco
Inc. (IV-D-357); Total Petroleum, Inc (IV-D-354); U.S. Steel Group, The (IV-D-340); Union
Carbide Corporation (IV-D-293)
1.2 Comments in Response to March 21, 1996 Policy Paper
SUMMARY: Industry commenters, in general, questioned EPA's authority to use CE to establish
a violation under the Act. Some commenters argued that any attempt by EPA to authorize the
use of non-reference test data as credible evidence for documenting underlying noncompliance
with an emission standard violates the express language of section 113(e) of the Act. Citing the
Congressional Record, many commenters point out that section 113(e)(1) refers expressly to
penalty assessment and only allows the use of credible evidence to establish the duration of a
violation. This interpretation of section 113(e) is confirmed, argues one commenter, by the
statement of Senator Chafee on this portion of the 1990 Clean Air Act Amendments:
Subsection 113(e)...clarifies and confirms that once EPA establishes evidence of a
violation using a formal test method, EPA can use other credible evidence to prove
additional violations, or that violation has continued. An addition, subsection
113(e) clarifies and confirms that once EPA has made a prima facia case that
establishes a period of violation, the burden of proving any intervening days of
compliance rests with the source. [135 Cong. Rec. S9665 (1989)]
In short, these commenters argued that the legislative history of section 113(e) ratified the
holdings in the body of case law which require that to establish a violation, EPA must use
applicable reference test methods.
On the other hand, at least one environmental group and a State agency association argued that
the Act specifically permits the use of CE for compliance determinations -- sections 113(a) and
(d) provide for enforcement "on the basis of any information available." These commenters
stated
that, on the one occasion a court misinterpreted these provisions (Kaiser Steel), Congress acted to
reenforce its intention given that section 113(e) specifically overturned the Kaiser Steel decision.
In response, some industry commenters argue that section 113(a) is not new; it was not amended
in 1990 to alter the standard of proof of a violation. (In fact, some commenters argued, Congress
implicitly acknowledged the more limited interpretation of section 113 by not modifying section
113(a).) EPA's new interpretation of section 113(a) renders 113(e)(1) superfluous, according to
these commenters. Another commenter pointed out that section 113(e) did override the Kaiser
Steel decision but only to allow EPA to use credible evidence to determine the duration of a
violation, not to prove a violation in the first instance. Taking a slightly different approach, yet
another industry commenter claimed that section 113(a)(1) does say EPA can use any
information
available to allege a violation, but that EPA's rules do not allow the use of evidence other than
that specified in the emission standard as a compliance method.
RESPONSE: See the response provided above in Section 1.1. The Agency acknowledges that,
in some cases which narrowly construed EPA's regulations, those regulations have been
interpreted to not allow use of evidence other than the established compliance methods even
though the statute does not limit EPA's authority in that manner. It is this dichotomy between
EPA's statutory authority and some courts' interpretation of EPA's regulatory authority that EPA
is correcting by promulgating the CE revisions. Thus, the final comment summarized above is
fully consistent with this rulemaking.
EPA rejects the suggestion that section 113(e) codified case law holding that violations can only
be proved with a reference test. First, EPA believes that the case law does not require use of
reference tests as a statutory matter. Secondly, this argument is inconsistent with the intent of
the
1990 Amendments to the Clean Air Act which were intended to expand, not contract,
enforcement authority. It is also inconsistent with other arguments forwarded by industrial
commenters that section 113(e) pertains to penalties only, in that penalties can not be assessed
for
days on which violations have not been established. If credible evidence can be used to establish
penalties, it must also be used to establish violations. There is little reason to suggest that
credible
evidence is sufficiently reliable that it can be used to establish violations and assess penalties on
the day after a reference test, but not on the first day.
Commenters' argument that Congress' amendment of section 113(e) impliedly amends section
113(a) is strained. According to the commenters, Congress amended section 113(e) to correct
the decision in Kaiser Steel concerning use of credible evidence to show duration of a violation.
Because Congress only addressed use of credible evidence to show duration of a violation, the
commenters argue, Congress impliedly ratified that under section 113(a) violations can only be
established by a reference test. However, Kaiser Steel only involved interpretation of an EPA
regulation and not whether that regulation was compelled by section 113(a). Thus, it is quite a
leap to argue that Congress' overruling of one application of EPA's compliance testing
regulations converts those regulations otherwise into a statutorily-compelled statement
concerning EPA's authority. This is particularly the case when erecting the regulations as
statutorily compelled directly contradicts EPA's authority as specified in section 113(a).
COMMENTERS:
American Petroleum Institute (IV-D-794; IV-D-822); American Electric Power (IV-D-836);
Arizona Mining Association (IV-D-834); Associated Industries of MO(IV-D-793); Chemical
Manufacturers Association (IV-D-823); Cinergy (IV-D-820); Class of 85 Regulatory Response
Group (IV-D-831); Clean Air Implementation Project (IV-D-787); Clean Air Services Steering
Committee (DoD) (IV-D-804); Coalition for Clean Air Implementation (IV-D-819); Corporate
Environmental Enforcement Council (IV-D-785); Dupont (IV-D-814); Eastman (IV-D-832);
Exxon Company, U.S.A. (IV-D-816); Fertilizer Institute (IV-D-802); Gas Processors Association
(IV-D-841); General Electric (IV-D-818); Independence Power & Light (IV-D-798); Los
Angeles Department of Water and Power (IV-D-806); Integrated Waste Services Association
(IV-D-829); Judy Kosovich (IV-D-840); Mobil Corporation (IV-D-821); Natural Resources
Defense Council (IV-D-789); NEDA CARP (IV-D-781; IV-D-826); NESCAUM (IV-D-803);
OH Chemical Council & OH Chamber of Commerce (IV-D-813); Public Service Company
(IV-D-835); Steel Manufacturers Association & Specialty Steel Industry of North America
(IV-D-833); Southwestern Public Service Company (IV-D-810); Texas Title V Planning
Committee (IV-D-796); Trial Lawyers for Public Justice (IV-D-780); UARG (IV-D-782;
IV-D-824); WV
Manufacturers Association (IV-D-842)
SECTION 2: Definition of "Credible Evidence" and Its Use for Determining Compliance
2.1 Comments in Response to Original EM Proposal
2.1.1 General Appropriateness of Using Enhanced Monitoring Data for
Compliance Determinations
SUMMARY: Environmental organizations stated that EPA's authority to use monitoring data as
a basis for enforcement actions was clear from Congress' intent and the legislative history to the
1990 Amendments, which documents that enhanced monitoring is based on the NPDES
"monitoring for enforcement" model. In fact, these environmental organizations noted, many
States use monitoring data for enforcement purposes now. An industry commenter said that the
proposed rule was an improvement over existing regulations by allowing use of continuous
monitoring in place of traditional compliance determination procedures.
However, many industry and some State agency commenters opposed using enhanced
monitoring
data for compliance determinations for general reasons. Commenters noted generally that data
from monitoring other than compliance test monitoring, or its equivalent, cannot be conclusive
evidence of a violation of an underlying standard, while one local agency recommended that
permitting authorities should be given discretion as to whether to require enhanced monitoring to
be used for direct compliance.
Some commenters suggested that enhanced monitoring data be used for indicating, not
determining, compliance status, because no monitoring method could be guaranteed to perform
properly and because this approach would make the proposed rule easier to implement by
eliminating the need for a rulemaking and the need for time-consuming analyses to determine
whether enhanced monitoring would change underlying standards. Commenters also noted this
approach would be consistent with existing compliance indicator monitoring requirements,
would
reduce the significant parameter correlation technical issues, and could be used to trigger more
extensive monitoring or testing for direct compliance. Another commenter objected to the use of
the data for enforcement because existing continuous emission monitoring systems (CEMS) that
are not used for compliance purposes would need to be upgraded, with great effort and expense,
to meet enhanced monitoring requirements.
A trade association argued that enhanced monitoring should not replace the use of test methods
because, unlike standard test methods, enhanced monitoring results will not be scientifically
duplicatable. Therefore, neither the source nor EPA will be able to extrapolate stack
test/enhanced monitoring correlation results at a reduced percentage of production up to full
production to determine, using surrogate parameters, whether limits will be complied with during
full utilization of production equipment. This result will lead to sources not being able to operate
at full capacity, they allege. A State agency argued that EPA has ignored the possible defenses
to
direct enforceability that use of non-test method data would present, while a local agency stated
that permitting authorities should be granted discretion as to whether enhanced monitoring data
may be used for direct enforcement.
RESPONSE: The EPA notes that this rulemaking does not address the enhanced monitoring
requirements proposed October 22, 1993, and therefore these comments are not specifically
germane to this rulemaking. The use of monitoring as opposed to the exclusive use of test data
to
establish violations, however, is germane to this rulemaking and has been responded to in section
1.2 above. The type of monitoring required to satisfy the enhanced monitoring requirement of
the
statute will be addressed in the CAM rulemaking. See 61 FR 41991 (August 13, 1996). As
discussed in the CAM materials referenced in the Federal Register notice cited above, EPA
currently intends that the CAM rule generally will provide a reasonable assurance of compliance
with emission limits through monitoring of control equipment.
The Agency further notes that this rulemaking does not replace the use of test methods. As
explained in detail in section III.A. of the preamble to the final rule, the party seeking to use
credible evidence to prove compliance or noncompliance will need to show that the information
produces results that are relevant to whether a reference test would have been passed, i.e. that
they reflect a reasonable approximation of, or can be related to, the emission values that would
be
generated from a reference test. The Agency acknowledges that there may be technical issues
related to particular information that a party may seek to introduce as credible evidence in any
particular case. The proffer of evidence and the defenses or rebuttal of that evidence are proper
and traditional roles for the customary rules of evidence and do not present any unique concerns
or issues in the context of enforcing air pollution requirements as opposed to other legal
requirements. The Agency recognizes that both judicial and administrative tribunals routinely
make determinations concerning the admissibility and weight of evidence on a case-by-case
basis.
Such evidentiary evaluations are standard under the Federal Rules of Evidence (FRE). See, e.g.,
FRE Rule 104 (regarding general admissibility), Rules 401-403 (regarding relevance), and Rules
701-705 (regarding opinion and expert testimony). This process should resolve the concerns
about credible evidence not being capable of confirmation or useful for extrapolation from stack
test results. For EPA's position on the reliability and credibility of various forms of possible
credible evidence (such as CEMS, COMS and similar data), and on the potential use of such data
in enforcement actions, see Section III.A of the final rule preamble.
COMMENTERS:
Alabama Department of Environmental Management (IV-D-453); American Automobile
Manufacturers Association (IV-D-538); American Foundrymen's Society, Inc. (IV-D-294);
American Portland Cement Alliance (IV-D-284); Chemical Manufacturers Association
(IV-D-301); Council of Industrial Boiler Owners (IV-D-319); Eastman Chemical Company
(IV-D-347); International Business Machines Corporation (IV-D-238); Koch Industries
(IV-D-332); Monsanto Company (IV-D-273); Natural Resources Defense Council, et al.
(IV-D-225);
Ohio Manufacturers Association (IV-D-348); Ohio Cast Metals Association (IV-D-324);
Regional Air Pollution Control Agency (IV-D-532); Rubber Manufacturers Association
(IV-D-331)
2.1.2 Use of Opacity Data to Determine Compliance with Particulate
Matter Standards
SUMMARY: Certain commenters objected to the possibility that continuous opacity
monitoring
system (COMS) or visible emission data could be used as a parameter to show compliance with
particulate matter standards. Two commenters stated that in United States v. New Boston Coke
Corp., Case No. C-1-84-1427 (S.D. Ohio August 16, 1985) [cited as New Boston Coke Corp. in
remainder of this document], the court held that although EPA can use opacity as grounds for an
NOV, EPA cannot use opacity as sufficient proof of a violation of mass particulate matter
emission limitations. These commenters stated that while opacity can indicate high mass
particulate concentrations, it is an inexact indicator that has traditionally been deemed
supplemental to particulate standards and limitations. One commenter argued that EPA has not
presented any data or scientific evidence supporting the use of COMS as a compliance method
for
particulate matter, so using it for that purpose would be arbitrary and capricious. Because of
these concerns, commenters recommended stating explicitly that COMS will not be used for
compliance with particulate matter standards.
RESPONSE: Unlike the proposed enhanced monitoring provisions, this rulemaking does not
require an owner or operator to establish any new procedures for determining compliance. The
ability of a party to prove compliance or the existence of a violation of a mass particulate matter
standard based on opacity monitoring data will require the party that seeks to introduce such
evidence to establish the comparability of the opacity data to the information that could be
obtained through the conduct of particulate matter compliance tests. The technical issues raised
by these commenters will present issues of fact to be established by the party seeking to use the
opacity data. The rulemaking does not create any presumptions or inferences pertaining to any
particular form of CE or any particular emission standard, including presumptions related to
proving a violation of a mass particulate matter standard based on opacity data. See the response
to Section 4.2 for a discussion of the New Boston Coke Corp. case.
COMMENTERS:
Armco Steel Company (IV-D-395); Cincinnati Gas & Electric Company (IV-D-259); Ohio
Edison Company (IV-D-266)
2.1.3 Use of Other Data to Determine Compliance
SUMMARY: Several commenters argued that EPA had focused too much on the use of
enhanced monitoring data alone to determine compliance. Certain commenters stated that the
proposed rule exceeds statutory authority by providing that enhanced monitoring data can be
used
as the sole basis for determining compliance with underlying emission standards. Although
monitoring data can play an important role in determining compliance status, other data must be
permitted to demonstrate compliance status.
Certain commenters stated generally that sources should be allowed to supplement enhanced
monitoring data with other data to demonstrate compliance, especially for any periods in which
enhanced monitoring data are not available. Other commenters, however, argued that only data
meeting the stringent quality requirements of an enhanced monitoring protocol should be used to
determine compliance, or, in the alternative, the final rule should limit "other data" to assess
compliance to only data meeting the requirements of EPA test methods in 40 CFR part 60,
appendix A.
RESPONSE: As discussed in response to Section 2.1.1, this rulemaking does not address the
proposed enhanced monitoring requirements, and therefore these comments are not specifically
germane to this rulemaking. However, EPA generally agrees with the comments concerning the
ability to use any relevant and probative data to demonstrate compliance status, and believes that
this rulemaking is consistent with that approach to compliance determination. Note, however, if
an independent provision in a SIP, permit or other rule requires that a reference test be
performed,
the credible evidence rule does not change this requirement or allow the use of credible evidence
to substitute for that specific requirement for the performance of a reference test.
COMMENTERS:
Alabama Department of Environmental Management (IV-D-453); Bunge Corporation
(IV-D-444); Council of Industrial Boiler Owners (IV-D-319); Dow Chemical Company
(IV-D-260); Entergy (IV-D-281); Motorola Inc. (IV-D-302); Ohio Manufacturers Association
(IV-D-348); Synthetic Organic Chemical Manufacturers Association (IV-D-362)
SUMMARY: Another commenter stated that EPA has erroneously concluded that enhanced
monitoring data must constitute court admissible evidence, when any data that is certified by a
source (as required by the title V compliance certification procedure) will constitute court
admissible evidence without the unnecessarily detailed and superfluous conditions required by
the
proposed rule.
RESPONSE: As discussed in response to Section 2.1.1, this rulemaking does not address the
proposed enhanced monitoring requirements, and therefore these comments are not specifically
germane to this rulemaking. In this rulemaking, EPA has specifically declined to make
conclusions or presumptions about what constitutes admissible evidence, believing those issues
to
be the province of the judiciary. However, EPA expects that any data certified by a source
should
constitute evidence admissible in court and this rulemaking will assure that EPA's regulatory
provisions are consistent with that approach.
COMMENTERS:
E.I. Dupont de Nemours and Company (IV-D-329)
SUMMARY: A State agency supported allowing the use of data gathered by CEMS required by
programs other than the enhanced monitoring program to determine compliance with applicable
emissions standards. The agency noted that it makes sense to put to good use the data from
CEMS that have already been installed, and in appropriate circumstances the data should be used
for direct enforcement.
RESPONSE: The EPA agrees that non-reference data that is already quantified in the same units
as the underlying standard, e.g., emissions data generated by properly operating and calibrated
non-reference CEMS, should generally be comparable to reference test data, with all specified
averaging periods still applying.
COMMENTERS:
Ohio EPA (IV-D-283)
2.1.4 Clarifications of "Other Credible Evidence" Provisions
SUMMARY: Some commenters suggested that the rule clarify what constitutes "other credible
evidence." An industry commenter said that credible evidence should be limited to what is in the
permit for testing and/or enhanced monitoring in order to preserve the permit shield and to avoid
conflicting data problems. A State agency suggested that EPA issue guidance that lists examples
or lists the type of information that could be considered credible evidence. The agency also
recommended clarifying whether any information can be used as credible evidence or if only
information required in the permit can be used as credible evidence. The agency did not believe
it
is necessary or appropriate to attempt to limit what a trier of fact may consider in determining
compliance in a permit or otherwise and further believed it is unwise to attempt to speculate as to
the evidence that may arise in untold future situations.
RESPONSE: The amendments to existing regulations on this issue (40 CFR 51.212, 52.30,
60.11 and 61.12) provide that a court generally may consider any credible evidence -- including
evidence other than that produced by the applicable test method -- in an enforcement action.
However, in order to avoid limiting what may be considered "any credible evidence," EPA has
decided not to provide a precise definition or description. The conforming amendments do,
however, retain the reference test methods as a benchmark for quantifying the emissions at issue.
Therefore the rules provide that the evidence must be relevant to the source's emissions as would
be determined by a reference test. See the response to Section 2.1.1 for further discussion on
this topic. The Agency also notes that "other credible evidence" would not be limited to
information that is required to be obtained in a permit.
COMMENTERS:
American Textile Manufacturers Institute (IV-D-440); Texas Natural Resource Conservation
Commission (IV-D-371)
2.1.5 Use of Non-Enhanced Monitoring Data
SUMMARY: A commenter proposed that demonstrating compliance with an enhanced
monitoring protocol should shield a source from enforcement using any other data. The
commenter added that the proposed ability to use any other information to rebut the enhanced
monitoring data is inconsistent with the determination of "best" in selecting an enhanced
monitoring protocol and is contrary to the permit shield and other general implementation
concepts of title V upon which part 64 is purportedly based.
Other commenters, however, said that use of data generated outside of an approved enhanced
monitoring protocol should be reciprocal so that a source could rely on non-enhanced
monitoring,
credible data to document or certify that it is in compliance. These commenters argued that if
EPA is unwilling to restrict itself to using data from federally-enforceable methods to prove
violations, EPA should not restrict permittees to using data from federally-enforceable methods
to
prove and certify compliance.
RESPONSE: As discussed in response to Section 2.1.1, this rulemaking does not address the
proposed enhanced monitoring requirements, and therefore these comments are not specifically
germane to this rulemaking. However, the Agency does agree generally that the use of data
should be reciprocal, i.e., a party should be able to show compliance or noncompliance in an
enforcement proceeding (or in a compliance certification) on the basis of any credible evidence.
This rulemaking adopts that reciprocal approach to the use of information. Further, while one
cannot rule out the possibility that other evidence might undermine the credibility of an approved
enhanced monitoring device (should such a protocol ever be established), one would generally
expect that such monitoring device would ordinarily produce results that are dispositive of the
issue.
EPA's approach to credible evidence is not inconsistent with the permit shield concept in that the
shield is designed to define what substantive requirements the source may or may not have. It
does not, and may not shield the source from the procedural use of credible evidence to prove
noncompliance with the emission limitation requirements the source does have. Further, EPA
reiterates that violations can be proven exclusively by CE, just as CE can be used in compliance
certifications pursuant to Part 70, without the need to perform a confirming reference test, for the
reasons mentioned in the comments above and the final rule preamble in Section III.C. and D.
While CE can be used for compliance certifications, this does not remove requirements to
perform
reference tests if the source is otherwise required to perform such tests, whether pursuant to a
Section 114 demand or a permit or other requirement to perform periodic performance tests.
COMMENTERS:
Can Manufacturers Institute (IV-D-478); Colorado Association of Commerce and Industry
(IV-D-243); Dow Chemical Company (IV-D-260); Fort Howard Corporation (IV-D-233)
2.1.6 Necessity for a Rulemaking to Establish Compliance Test Methods
SUMMARY: Numerous industry commenters stated that EPA must follow rulemaking
procedures if it intends for enhanced monitoring to be used as a direct compliance test method in
order to ensure that the stringency of existing requirements is not altered. Many commenters
argued that the proposed approach of establishing directly enforceable enhanced monitoring
through permits would in effect modify the compliance obligations and requirements, as well as
the level of monitoring, reporting and record keeping, in existing regulations. Many commenters
argued generally that emission standards include methods for telling whether a source meets the
requirements. When these methods are changed and new monitoring, record keeping, and testing
methods are established, the standards themselves are changed. Others noted that the underlying
emissions control requirements that are to be monitored limit the types of improved monitoring
that can be required. Commenters argued that regulatory agencies must use rulemaking, not
operating permits, to alter existing emission standards.
Many commenters also stated that for most underlying standards, EPA must follow rulemaking
procedures that take into account various statutory criteria for establishing standards. These
commenters stated that, for instance, any enhanced monitoring for NSPS standards must be
established so that the standards remain achievable using the controls determined to be the best
demonstrated technology at the time the standards were established, must take into account costs,
and energy and environmental impacts, and must apply prospectively to sources for which
construction is commenced after the initial proposal of the revision to the individual NSPS
subpart. The commenters argued that similar types of requirements will exist for other standards
such as RACT, LAER and NESHAP requirements.
Another reason provided by commenters as to why individual rulemakings are required to
establish new compliance test methods are the legal cases on point. Commenters stated that
under the decision in Donner Hanna Coke Corp.v. Costle, 464 F. Supp. 1295 (W.D.N.Y.
1979)[cited as Donner Hanna in the remainder of this document] , EPA can change the means for
determining compliance with a standard (i.e., the test method) only through formal notice and
comment rulemaking. One trade group argued that, in the past, EPA has unsuccessfully
attempted to revise test method and monitoring provisions without following proper rulemaking
procedures (citing PPG Industries v. Costle, 630 F.2d 462 (6th Cir. 1980) and U.S. v. Zimmer
Paper Products, Inc., No. IP-88-194-C (S.D. Ind. 1989)). Similarly, the commenters argued that
the decision in Portland Cement Association v. Ruckelshaus, 486 F.2d 375 (D.C.Cir. 1973), cert.
denied, 417 U.S. 921 (1974) [cited as Portland Cement in the remainder of this document], states
specifically that the validity of an NSPS standard is questionable if there is a significant
difference
between the techniques used to arrive at the standard and the techniques used to determine
compliance with the standard. According to the commenters, all of these cases require that EPA
establish compliance test methods through rulemaking in a manner that considers the effect of
the
test method on the standard itself. Commenters also noted that supporting documentation
provided in the RIA indicates that even EPA itself believed that modifying NSPS requirements
through the proposed part 64 approach might not be permissible.
Certain commenters also stated that EPA could not attempt to force States to establish test
methods through permits. In Train v. NRDC, 421 U.S. 60 (1975), the Supreme Court established
that while EPA must set ambient standards, it is up to the States to determine -- through SIPs, not
permits -- how to meet them. In addition, certain commenters also argued that EPA cannot use
the title V process to change SIP compliance methods because that amounts to increasing the
stringency of a rule which can only be effectuated through section 110 SIP revision procedures,
and that changing SIP compliance methods through permits would create conflicts with the
underlying SIP provisions. Commenters stated that substituting a new averaging time as
contemplated under the proposed rule would dramatically affect the stringency of existing limits
and the overall effect of certain SIPs, but the current rulemaking would offer no opportunity to
prepare or present comments on that effect in the context of revising the SIP.
One commenter discussed Indiana & Michigan Electric Co. v. EPA, 733 F.2d 489 (7th Cir.
1984), in which the court held that when reviewing a revised SIP, EPA must consider limitations
(such as averaging periods) that may be essential to the plan. Another commenter discussed the
Ohio SIP as an example. According to this commenter, this SIP does not specify a
federally-approved averaging time, because EPA wished to avoid this issue when the SIP was
established.
Commenters argue that EPA cannot now resolve this issue under the guise of enhanced
monitoring rulemaking without considering any of the data, information, or record specific to
Ohio's SIP. Therefore, they suggest that if EPA is to establish an averaging time for Ohio's SIP,
it
must be established through the section 110 process. The commenters argued that these
examples
point out the need for a formal SIP rulemaking to establish compliance test method procedures.
Another example of why rulemakings are required, according to certain commenters, is their
perception of EPA's efforts to use CEMS in Subpart D under the NSPS. Commenters suggested
that the different approaches to developing the initial NSPS Subpart D, the subsequent Subpart
Da, and then the proposed revisions to Subpart D are good examples of the different approach
that is taken in establishing continuous compliance standards. Different data and analyses are
used, and, commenters argue, deliberate choices are made in the standard-setting process which
create an interrelationship between averaging time, compliance test frequency, control system
characteristics, and the emission limit. The commenters contend that the initial Subpart D was
developed on the basis of limited data without a continuous compliance test requirement or
associated averaging time, while in Subpart Da, EPA relied on extensive data and statistical
analyses to develop an integrated continuous compliance test approach with an associated
averaging time to account for statistical variability. The commenters then noted that in the
proposed revisions to Subpart D, EPA proposed to establish a long-term averaging time to
account for statistical variability of emissions. The commenters stated that these rulemaking
examples demonstrate that developing compliance method specifications for a particular
emission
limitation or standard involves substantial and unique issues of fact and law that can only be
resolved through rulemaking.
An industry coalition group commenter noted that EPA just recently reiterated its position that
test methods must be specified in a SIP because the test method and associated error can affect
the implementation and stringency of any SIP regulation. This statement is in direct opposition
to
the non-replicable, case-by-case methods that will be imposed through the proposed enhanced
monitoring program.
RESPONSE: The CE rulemaking does not amend applicable emission standards or reference
tests. Thus, the majority of these comments are irrelevant to this rulemaking. See final rule
preamble, particularly Section III.C. and III.D., especially III.D.5. See also the responses in
section 4 of this document. EPA notes that some commenters have referenced prior EPA
statements about the importance of the compliance method in establishing the stringency of an
emission limit or standard. See, e.g., 58 FR 61640, 61644 (November 22, 1993) (in which EPA
stated that the specification of test methods in a SIP are important because the test method and
associated error can affect the stringency of the SIP-specified regulation). As discussed in
Section III.A. of the final rule preamble, the CE revisions continue to rely on the established
compliance method as the benchmark for measuring compliance with the standard. The use of
other evidence to document a violation must take into account the averaging requirements related
to the data collected by such method, the pollutant constituents measured by such method (e.g.,
the definition of particulate matter included in Method 5), and any limitations as to the
conditions
under which such tests may be conducted. The CE revisions are not intended to undermine the
importance of a reproducible test method as part of an applicable rule.
EPA does not believe this rulemaking runs afoul of the Act's division of authority between EPA
and the States. EPA does not believe that this rulemaking forces States to establish test methods
through permits. This rulemaking does not involve amendment of existing methods in SIPs;
rather, it specifies that SIPs must not preclude the use of credible evidence or information for the
purpose of submitting compliance certifications or establishing whether or not a person has
violated or is in violation of any emission standard. Moreover, the regulatory language
specifically retains the existing test methods as the reference point for determining the credibility
of the evidence or information. Modifications of SIPs will be sought by EPA through existing
statutory procedures. Further, this rulemaking does not make SIP requirements more stringent or
affect averaging times established by SIPs. The stringency issue and the question of averaging
times is addressed in the preamble at Section III.D.1.
EPA does not believe that the cases cited are on point. The Donner Hanna decision, to the extent
that it may be construed to hold that test methods may only be changed by formal rulemaking,
does not also hold that where the test method is not being changed, credible evidence which is
relevant to whether the test method would have shown violations may not be used to show
violations. To the extent that some may suggest that this decision can be interpreted to also hold
the same, which EPA believes is a strained reading of Donner Hanna, then Donner Hanna is
inconsistent with sections 113(a) and 113(e). The same is true of the other cases cited that
pertain to test methods, PPG Industries v. Costle, U.S. v. Zimmer Paper Products, Inc., and
Portland Cement.
Regarding the claim that the aborted subpart D revisions show that compliance method changes
must be accomplished by case-specific rulemaking, EPA believes that CE is not a change in the
test or compliance method, but is merely another way to show what the compliance method
would have shown. For further discussion of the Subpart D issue, see Section 4.1.1.
COMMENTERS:
ALCOA (IV-D-288); American Automobile Manufacturers Association (IV-D-538); American
Electronics Association, Clean Air Task Force (IV-D-437); American Foundrymen's Society,
Inc.
(IV-D-294); American Gas Association (IV-D-265); American Portland Cement Alliance
(IV-D-284); Arkla Energy Resources Company (IV-D-343); Armco Steel Company (IV-D-395);
ASARCO (IV-D-327); Ash Grove Cement Company (IV-D-311); Baltimore Gas and Electric
Company (IV-D-296); Chemical Manufacturers Association (IV-D-301); Cincinnati Gas &
Electric Company (IV-D-259); Clean Air Implementation Project (IV-D-242); Coalition for
Clean
Air Implementation (IV-D-304); Consolidated Natural Gas Company (IV-D-350); Council of
Industrial Boiler Owners (IV-D-319); East Ohio Gas Company, The (IV-D-355); Eastman
Chemical Company (IV-D-347); ENRON Operations Corp. (IV-D-390); Exxon Chemical
Americas (IV-D-339); Exxon Company, USA (IV-D-310); Fertilizer Institute, The (IV-D-251);
Goodyear Tire and Rubber Company, The (IV-D-292); KBN Engineering and Applied Sciences,
Inc. (IV-D-475); Kennecott Corporation (IV-D-262); Large Public Power Council (IV-D-336);
Lubrizol Corporation, The (IV-D-306); Mississippi River Transmission Corp. (IV-D-344); Mobil
Oil Corporation (IV-D-285); Monsanto Company (IV-D-273); National Environmental
Development Association (IV-D-334); New United Motor Manufacturing, Inc. (IV-D-467);
Occidental Chemical Corporation (IV-D-240); Ohio Cast Metals Association (IV-D-324); Ohio
Chamber of Commerce (IV-D-370); Ohio Edison (IV-D-266); Ohio Electric Utilities Institute
(IV-D-323); Rubber Manufacturers Association (IV-D-331); Shell Oil Company (IV-D-280);
Southwestern Public Service Company (IV-D-272); U.S. Steel Group, The (IV-D-340); Union
Carbide Corporation (IV-D-293); United States Sugar Corporation (IV-D-382); Utility Air
Regulatory Group (IV-D-489); Whirlpool Corporation (IV-D-493)
2.2 Comments in Response to March 21, 1996 Policy Paper
SUMMARY: A majority of industry commenters expressed concern that the Agency has not
clearly defined CE, which in turn raises questions about compliance obligations. The
commenters
argued that the Agency's position on the use of CE illegally deprives sources of reasonable notice
of what constitutes compliance by replacing, in a single rulemaking, specific methods of
determining compliance with state and federal emission limit regulations promulgated over the
past 25 years with undefined and indeterminable methods. In fact, they argued, the use of CE
would be unconstitutionally vague and violate due process. It would render completely unclear
what a company can consider to be compliance or non-compliance with a standard. (In this
context, several industry commenters cite General Electric Co. v. U.S. EPA, 53 F.3d 1324 (D.C.
Cir. 1995), relating to fair warning.) As a result, one commenter claimed companies would be
forced to comply without bounds or limits.
Because they perceived the definition of CE to be broad and ambiguous, some industry
commenters suggested that compliance determinations would become vague and subjective, and
that standards would, as a result, be applied inconsistently from state to state and from source to
source. As one commenter explained, it is the complete subjectivity of CE that is most
repugnant
to environmental professionals -- the phrase implies potential acceptance of "proofs" or
"evidence" that are not subject to the rigors of scientific protocols. The courts, another
commenter explains, have held that companies need objective, quantitative methods of
demonstrating compliance and that any standard whose violations may trigger penalties must be
supported by specific, objective compliance methods. In Grayned v City of Rockford, 408 U.S.
104 (1972), for example, the court held that a vague law impermissibly delegates basic policy
matters to policemen, judges and juries for resolution on an ad hoc, subjective basis. What
amounts to a post hoc determination of the definition of a violation, another commenter argues,
would erode reasonable predictability for sources striving to comply. Because the concept is
vague and can be interpreted in many ways, the commenters asserted that the use of CE would
exponentially increase the number of controversies and questions and may invite distracting,
time-consuming disputes and inquiries.
Anticipating the possibility that parametric monitoring data could constitute CE, many industry
commenters addressed this issue. In short, the industry comments reflected a general consensus
that, in order for compliance evidence to be considered credible, it must be traceable to a
reference method. In addition, one commenter asserted that since EPA does not and cannot
demonstrate that any evidence is equivalent to reference test methods, the rule is scientifically
unsupportable. Elaborating on this concept, another commenter explained that parametric
relationships with emissions are only reliable for operating ranges over which they were
developed. To establish correlation above the standard would require operation above the
standard; extrapolation would not be valid for predicting non-compliant operation. If, on the
other hand, emission standard violations were ultimately alleged based on an exceedance of an
upper boundary of a parametric relationship which is below the standard, that would be a clear
case of causing increased stringency.
The commenters were concerned that, by removing the restrictions on using CE, EPA will
encourage regulatory agencies to use control system operating parameters as an indirect indicator
of emissions instead of much more accurate reference method test data. Correlations between a
single operating parameter and pollutant emissions, some argued, are often weak and imprecise
(e.g in the case of fabric filters), and assumptions that correlations between monitored parameter
values and the emission limit extending from normal operating ranges to all operating situations
are frequently invalid. Furthermore, commenters asserted that process information alone cannot
be relied upon because it represents an indirect and unsubstantiated indication of non-compliance
-- there are too many operating factors involved to simply say that when a parameter is
off-specification that there is necessarily a compliance problem. The use of process data as a
surrogate for compliance with emission standards is not always representative and could lead to
"false positives," according to these commenters. (For example, commenters noted that courts
have ruled that subjective opacity test results are not admissible as evidence of compliance.) In
short, another commenter argued, parameter monitoring can establish compliance, but not
noncompliance.
Capturing most of the concerns raised with respect to the definition of credible evidence and the
use of parametric data, an industry commenter suggested that the decision in International Paper
Co. v. Town of Jay, et al., 655 A.2d 998 (Me. 1995)[cited as Town of Jay in the remainder of this
document], demonstrates why the use of credible evidence is unreliable, unfair and results in an
impermissible shifting of the burden of proof. This case, the commenter argued, underscores the
fact that a single operating parameter cannot be labeled as "credible" and form the sole basis for
finding a violation of an air emission limit. According to this commenter, air emissions are the
result of a complex interplay of various criteria, none of which can be evaluated in a vacuum to
form the basis for concluding a violation exists. This litigation also illustrated that it is
fundamentally unfair to the source to create a compliance protocol after commencement of a
lawsuit.
Some commenters made suggestions in terms of how the Agency could better define CE. One
suggested that uncorrelated data should be precluded from CE. For example, opacity data should
not be presumptively credible evidence of a violation of a PM limit, since significant technical
questions exist concerning the adequacy of opacity-mass correlations. Another commenter felt
that operating data from one emissions unit should not be considered as credible evidence for
determining emission problems at another -- only emissions unit-specific data should be used.
Yet
another suggested that the HON represents a good example of how parameter data can be used
for enforcement. Alternatively, commenters suggest, the CE revisions should specify an order of
preference with respect to types of data and information used for compliance determinations.
Another approach suggested would be to distinguish indicator monitoring from directly
enforceable monitoring, trust state and local agencies to know where and when more monitoring
is required and make clear that CAM monitoring will not be used as directly enforceable
evidence
of emission limit violations. A State and local agency association suggested that agencies should
be provided the option of determining whether or not to specify from the outset the types of CE
that would be considered in determining compliance and recommended that EPA provide
guidance about the definition of credible evidence, particularly relating to use of state and federal
rules of evidence for defining it. Finally, one commenter suggested that anonymous tips from
disgruntled employees or other adverse parties should be deemed not to be credible evidence.
Based on a follow-up meeting with the Agency to clarify the CE revisions, a utility submitted
comments which concluded that EPA recognizes the need for clarity and certainty for regulated
entities regarding their compliance obligations. The comments pointed to EPA's intention that
well-designed CAM plans (plus any reference test method data) should account for most if not
all
of the CE that could be used in determining compliance or noncompliance, and that those entities
that comply with their CAM plans will be the lowest priority for investigation or enforcement by
EPA.
The comments with respect to defining CE were not without inconsistency. While many seemed
to endorse a position that the rule should carefully and expressly limit evidentiary burdens on
sources and limit the universe of what constitutes CE, at least one commenter countered that
neither sections 113(a) or (e)(1) of the Act allow EPA to specify by rule what evidence is CE;
data are only credible after they have been subjected to the due process considerations afforded
by
the judicial system, according to this commenter. Yet another commenter suggested that CE
should be defined, and that criteria should provided in the rule to guide a court's review.
RESPONSE: See generally Section III.A. of the preamble to the final rule for a response to these
issues. With respect to some specific issues raised in these comments, EPA provides the
following additional responses.
(1) Use of Parametric Data. All of the technical arguments against the credibility of
parametric data to prove a violation of an emission limit are available to the party which
attempts to defend against the use of such data. Because the final rule does not attempt to
create any presumptions or inferences about particular forms of evidence, the party
introducing evidence, including test method data, will retain whatever burden of proof is
required by law in establishing that the evidence proves that an emission limit was
complied with or violated, as applicable. In certain situations, the Act does create
presumptions (see, e.g., section 113(e)(2)), in which case the burden of proof will shift as
directed by the Act. As noted in the August 2, 1996 draft CAM rule discussion document
(see 61 FR 41991, August 13, 1996), excursions from CAM indicator ranges are not
considered by the Agency to be presumptively an emission limit violation. Because of the
way CAM triggers may be set, emissions may be below the applicable limit even though
CAM parameters are exceeded. Accordingly, such CAM excursions would have to be
evaluated on a case-specific basis before one would know whether there has been a
violation. In contrast, since the CAM parameters are supposed to provide that operation
within those parameters provides a reasonable assurance of compliance with applicable
limits over the reasonably anticipated range of operating conditions, staying within a well
designed parameter range provides an owner or operator with a strong argument that
compliance has been achieved and thus, under the proposed CAM rule, would allow the
owner or operator to certify compliance in such circumstances. The Agency notes, as
discussed in Section III.A of the preamble to the final rule, that EPA cannot now
guarantee that this assumption will always be valid and that compliance with CAM
indicator ranges does not provide a formal "shield" against enforcement.
To the extent that arguments against parametric data suggest that EPA is poorly advised
to change from a system of compliance that is narrowly focused on data from a specific
test to one that allows consideration of a broad range of data , EPA replies that it is a
good policy choice to allow the use of credible evidence especially where reference test
method data are difficult to obtain. Often, reference test data are expensive and thus
infrequently obtained, or as in the case of opacity readings by a trained observer, time
consuming for Agency resources, as well as difficult. Take for example, Sierra Club v.
Public Service Company, 894 F. Supp. 1455 (D. Colo. 1995), in which the court held that
COMS data documented 19,000 violations of the 20% opacity standard in the SIP over a
five year period. EPA had to send an inspector a long distance out to the site of this plant
on several occasions to get a visual reading and frequently got no indication of violations
even though the arguably-more-accurate COMS data recorded tens of thousands of
violations without requiring any travel or time. Thus, using COMS to prove violations
gives a more complete and accurate picture of compliance and saves Agency resources.
(2) The IP vs. Town of Jay Decision. Although this case was raised in the comments to
document why the CE revisions should not be promulgated, the facts and judicial
decisions in the Town of Jay case highlight the wisdom of going forward with the credible
evidence rulemaking. First, the Maine Supreme Court found that the Town of Jay's
ordinance, with compliance provisions similar to the provisions in 40 CFR Parts 51, 52, 60
and 61 that are revised in the credible evidence rulemaking, established exclusive test
methods for proving a violation of the town's ordinance. Using a "plain meaning"
rationale, the court held that the town was bound by the explicit terms of the ordinance.
The court went on to state that: "If these methods are too restrictive in practice, the
Town can amend its ordinance . . . The Town cannot respond to the deficiencies of its
ordinance by rewriting it in the midst of an enforcement proceeding." See p. 10 of
Attachment D to IV-D-827. The court did not hold that it would be impossible to write
the ordinance to allow for the introduction of other evidence to prove a violation, but only
that the ordinance must be narrowly construed. The desire to avoid piecemeal judicial
interpretation -- which is not mandated by the customary rules of evidence or the
enforcement authority in section 113 (a) and (e) of the Clean Air Act -- leads to EPA's
decision to revise the comparable federal regulations and so provide a clear and consistent
set of rules.
The lower court decision in Town of Jay relied on a different legal interpretation to rule
against the violations found by the Town agency on the basis of non-test method data.
The lower court found that the Town had improperly created an inference or presumption
that the non-test method data were sufficient to prove particular violations. See p. 4-7 of
Attachment C to IV-D-827. The court went on to hold that, without the inference, the
Town had failed to introduce sufficient evidence to prove the violations. Id. at p. 8. The
final CE revisions do not include the presumptions of credibility that were included with
the proposed rule, and thus the rulemaking satisfies that aspect of the lower court's
objection to the Town of Jay's actions.
The lower court decision in Town of Jay did note that "any party that is going to be
judged in an enforcement action is entitled to reasonable, advance notice as to the criteria
upon which a violation will be judged." Id. at p. 4. By requiring that evidence must be
capable of being compared to test method results (see detailed discussion in Section 2.2.1,
above), EPA believes that the CE revisions do provide such notice even though the exact
types of potential credible evidence in any particular case are not explicitly stated. The
Agency believes that case-by-case determinations as to the specific evidence that may be
considered are properly left to the judiciary guided by published rules of evidence. The
Agency also notes that the lower court in Town of Jay was most concerned about this
issue where an inference or presumption was being applied against the source without any
prior notice.
COMMENTERS:
Air Control Techniques (IV-D-800); American Petroleum Institute (IV-D-794; IV-D-822);
AMP-OH (IV-D-788; IV-D-837; IV-D-838;IV-D-839); Associated Industries of MO
(IV-D-793); BHP
Copper (IV-D-776); BP Oil (IV-D-811); Chemical Manufacturers Association (IV-D-823); Clean
Air Act Services Steering Committee (DOD) (IV-D-804); Clean Air Implementation Project
(IV-D-787); Coalition for Clean Air Implementation (IV-D-819); Cyprus Miami Mining
(IV-D-791);
Dow (IV-D-825); Dupont (IV-D-814); Eastman (IV-D-832); Exxon Chemical Americas
(IV-D-795); Fertilizer Institute (IV-D-802); General Electric (IV-D- 818); IL Municipal Electric
Agency
(IV-D-808); Independence Power & Light (IV-D-798); IN Mineral Aggregates Association
(IV-D-797); Integrated Waste Services Association (IV-D-829); International Paper Company
(IV-D-827); Judy Kosovich (IV-D-840); Los Angeles Department of Water and Power
(IV-D-806);
Mobil Corporation (779); Muscatine Power (IV-D-807); National Stone Association (IV-D-828);
NEDA CARP (IV-D-781; IV-D-826); NESCAUM (IV-D-803); Northwest Pulp & Paper
Association (IV-D-815); OH Aggregates Association (IV-D-774); OH Chamber of Commerce
(IV-D-813); OH Chemical Council & OH Chamber of Commerce (IV-D-778); Pacific Gas
Transmission Company (IV-D-812); Precision Metal Forming (IV-D-817); Public Service
Company (IV-D-835); SOCMA (IV-D-805); Southwestern Public Service Company (IV-D-810);
STAPPA/ALAPCO (IV-D-786); Steel Manufacturers Association & Specialty Steel Industry of
North America (IV-D-833).
SECTION 3: CE Revisions Language (Parts 51, 52, 60 and 61)
3.1 Comments in Response to Original EM Proposal
3.1.1 Enhanced Monitoring Data as Presumptively Credible Evidence
SUMMARY: Several commenters said that it is a violation of the Act to make enhanced
monitoring results "presumptively credible evidence." Some commenters said that violations
must
be proven using applicable compliance test methods for a particular standard and that such
methods can only be modified through an appropriate notice and comment rulemaking for that
particular standard. Other commenters said that the enhanced monitoring proposal and SIP calls
will not provide the reasoned decision making required to create presumptively credible
evidence.
Some commenters said that in all events, non-test method credible evidence can only be used to
show the duration of a violation proven using the test method. Based on these positions, some
commenters suggested deleting the references in the conforming amendments to parts 51, 52, 60
and 61 which state that enhanced monitoring is presumptively credible data. Lastly, a
commenter
suggested that the requirement that enhanced monitoring provide presumptively credible
evidence
be deleted and that compliance be based on industry installing systems consistent with sound
engineering practices used by the chemical and process industries for process measurements, and
not CEMS.
Some commenters said that EPA cannot create presumptions of credibility for evidence because
it
would be an improper attempt to dictate rules of evidence; this would be especially true for SIP
limits subject to State rules of evidence. A commenter added that Congress did not (and could
not) authorize EPA to expand rules of evidence, and section 113(e) stands on its own without the
need for regulatory clarification. One commenter proposed clarifying that "presumptively" in
51.212(c)(1)-(2), 52.12(c)(1)-(2), 60.11(h)(2)-(3), and 61.12(f)(2)-(3) means that the
presumption is rebuttable, while another stated that data should pass appropriate legal tests
before
being considered "presumptively credible."
RESPONSE: As discussed in detail in Section II of the preamble to the final rule, EPA has
accepted these comments and has not included the lists of presumptively credible evidence that
were included in the proposed rule. This change addresses the comments summarized above.
The Agency also notes that EPA's decision not to define the precise types of evidence that
constitute "credible evidence" is consistent with the comment that section 113(e) stands on its
own without the need for regulatory clarification. The CE revisions do not attempt to clarify
section 113(e), but rather are aimed at implementing section 113(e), as well as the remainder of
section 113, in a manner consistent with congressional intent by removing perceived barriers in
EPA's rules.
COMMENTERS:
ASARCO (IV-D-327); Chemical Manufacturers Association (IV-D-301); Clean Air
Implementation Project (IV-D-242); Dow Chemical Company (IV-D-260); E.I. DuPont de
Nemours and Company (IV-D-329); Exxon Chemical Americas (IV-D-339); Exxon Company,
USA (IV-D-310); Fort Howard Corporation (IV-D-233); Monsanto Company (IV-D-273);
National Petroleum Refiners Association (IV-D-276); Shell Oil Company (IV-D-280)
SUMMARY: An air pollution control agency noted that proposed PS 101 in Appendix A states
that a VOC CEMS can only provide an indication of a relative concentration of mix of VOC in
the process stream. Given this statement by EPA, EPA should recognize that a VOC CEMS may
be inappropriate as other credible evidence.
RESPONSE: The CE revisions do not establish any presumptions or inferences about the
credibility of particular evidence, including data that may be produced by a VOC CEMS that is
operated consistent with proposed PS 101. The Agency notes that PS 101 is not included as part
of the credible evidence rulemaking and was not included in EPA's draft CAM rulemaking
materials. See 61 FR 41991 (August 13, 1996).
COMMENTERS:
Bay Area Air Quality Management District (IV-D-402)
3.1.2 Miscellaneous Issues
SUMMARY: Commenters recommended substituting "part 63 or 64" for "part 63" in the
"credible evidence" provisions in 52.12(c), 60.11(h) and 61.12(f).
RESPONSE: The Agency has decided not to include the applicable language from the proposed
rule referenced in this comment and therefore the requested change is no longer applicable.
COMMENTERS:
Chemical Manufacturers Association (IV-D-301); Exxon Chemical Americas (IV-D-339);
Monsanto Company (IV-D-273)
SUMMARY: A commenter recommended clarifying 52.12(c) to ensure that use of data for
direct compliance pursuant to proposed 52.12(c)(1)(i) will not be allowed until the SIP is
revised to authorize enhanced monitoring data to be used for such purposes. The commenter
objected to allowing federal courts to use enhanced monitoring data for compliance
determinations before the relevant SIP is revised for purposes of determining violations.
RESPONSE: As stated elsewhere, this rulemaking is intended to clarify that credible evidence
may be used in compliance certifications and to prove or disprove violations of emission
standards. It does so by revising relevant EPA regulations and calling for revisions of SIPs that
have been interpreted by some as not presently allowing the use of credible evidence for these
purposes. EPA's position is that, even prior to today's change in federal regulations, credible
evidence could be appropriately used in compliance certifications and enforcement cases
regarding both federal emission standards and SIP emission limits. Hence, while SIPs must be
revised as necessary to make it clear that credible evidence may be used for compliance
certifications and in enforcement cases, there is no need to wait for SIP revisions before using
credible evidence for these purposes.
COMMENTERS:
Monsanto Company (IV-D-273)
SECTION 4: Stringency of Underlying Requirements
4.1 Comments in Response to Original EM Proposal
4.1.1 Stringency of Underlying Requirements - Defining Compliance
SUMMARY: Environmental groups and one State agency stated explicitly that enhanced
monitoring does not increase the stringency of emission limits because an underlying premise of
Clean Air Act regulations is that sources must remain in compliance at all times unless explicitly
excused. However, numerous industry commenters argued that the enhanced monitoring rule
would impermissibly increase the stringency of underlying regulations by redefining compliance
and establishing new compliance methods and obligations. By overriding existing requirements
with respect to compliance test methods, the frequency of testing for compliance, the operating
conditions under which testing is performed, and compliance averaging periods, enhanced
monitoring would redefine "compliance," according to many commenters. Many commenters
stated generally that the compliance method is inextricably linked with the emission limit itself
and
that it is impossible to consider changing the compliance test method without a full evaluation of
the impacts any change might have on the emission limit. Commenters cited the holding in
Donner Hanna as support for the notion that the method of determining compliance with an
emission standard can affect the level of performance with the standard, and thereby alter the
standard itself; another commenter cited Wagner Electric Corp. v. Volpe, 466 F.2d 1013 (3d Cir.
1972), and BASF Wyandotte Corp. v. Costle, 598 F.2d 637 (1st Cir. 1979) as support for this
position.
Another commenter noted that the proposed rule could increase, for example, the stringency of
existing regulations for volatile organic compounds (VOC) under the surface coating protocol for
automobiles and light duty trucks. If a permitting authority requires a different reference method
for measuring VOC than the one specified in the protocol, a facility that was in compliance with
the method specified in the protocol could be out of compliance under the second method.
Where
the permitting agency increases the frequency of reporting, excursions that would average out
under the previous frequency of reporting would be considered violations. Any attempt to
change
Method 5 of Appendix B of 40 CFR part 60 as the compliance test method for particulate matter
was also cited as an example of the effect that changes to a test protocol can have on the
stringency of an emission standard. By varying filter temperature (as in Method 5B) or requiring
the inclusion of the impinger catch (as some States using Method 5 have specifically elected),
particulate matter becomes defined as that which is caught in a filter at 320 degrees F or in an
iced
impinger. Depending on the dew point of constituents in the gas stream, this can have a
substantial effect on the functional definition of particulate matter at a particular source or source
category, according to one commenter.
Many commenters argued that the establishment of only periodic compliance test requirements in
existing standards was part of a rational design of the applicable requirement and that the
periodic
requirement cannot be changed to a continuous method without affecting the stringency of the
standard. Commenters claimed that the 1983 proposed revisions to Subpart D (and the
associated supporting docket materials) demonstrate the link between the compliance method,
the
frequency with which the method is conducted, and the stringency of the emission limit. (See
related comments on subpart D averaging time issues in section 4.1.2, below.) Others pointed to
the opacity requirements in NSPS subpart BB and NESHAP Subpart O (and EPA's background
documentation for those standards) to show this relationship. Certain commenters claimed that
existing standards are often developed on too limited a database to be demonstrated as achievable
for all short term periods and are developed on the basis of statistical assumptions that are not
valid if compliance is continuously measured. One industry coalition group provided examples
of
the limited information on which certain standards have been developed along with statistical
demonstrations and arguments to support its argument that modification of compliance protocols
may increase the stringency of such standards. Industry commenters also pointed to the use of
longer averaging periods with standards having continuous compliance determination methods as
indicating that continuous compliance is only required where such compliance determinations
are
used.
As an example of how monitoring compliance on a continuous basis for standards developed
with
only limited data can increase stringency, certain commenters cited regulations promulgated by
EPA under section 308 of the Clean Water Act, which gave States discretion to establish pH
monitoring requirements for inclusion in NPDES permits. States began to include continuous
monitoring requirements in the permits, but at the time the pH standards were originally
established, it was intended that compliance would be determined through grab and/or composite
sampling procedures. Once the continuous monitoring was required, it became clear that the pH
standards could not be met 100% of the time, so EPA revised its requirements to provide that
compliance determined through continuous monitoring is achieved when standards are met 99%
of the time. These commenters stated that the enhanced monitoring rule must authorize the same
type of flexibility that was necessary in this situation.
Numerous commenters stated generally that EPA has incorrectly assumed that current definitions
of compliance require that sources achieve emission limitations under all operating conditions
and
for any averaging period. Commenters argued that although the proposed rule would require
compliance over a source's entire operating range, many current emission standards, including
many NSPS and NESHAP requirements, were not developed with allowance for variable
operating conditions, and were intended to be checked only periodically under "representative"
conditions.
For instance, certain commenters argued that some percent efficiency standards are tested at
maximum capacity. In some instances where a source operates at less than full capacity (and
hence has lower mass of emissions) the percent efficiency cannot be achieved. Commenters
stated that it would be inappropriate in such circumstances to find the source in violation when
the actual emissions from the source are less than the amount allowed at full capacity.
Commenters pointed to certain NOx standards as raising similar problems.
To further illustrate this point, other commenters discussed emission standards based on
concentrations, percentage reductions, performance-based mass standards, and installing specific
technologies. These commenters argued that complying with these standards has always been
defined as attaining the relevant limitation under the relevant operating conditions and that these
standards were not established requiring compliance under all operating conditions.
Other commenters stated generally that an emission limitation that is achievable under one set of
assumptions regarding monitoring frequency and the averaging period often will no longer be
achievable if the underlying assumptions are changed. For many standards, these commenters
argue, compliance has been defined as attainment of the applicable emission limitation at
specified
operating conditions. Certain commenters also argued that many current applicable standards
have established monitoring and compliance procedures that recognize the potential of many
types
of control devices to experience reduced efficiency over time, and that enhanced monitoring will
make such standards more stringent.
RESPONSE: As discussed in response to Section 2.1.1, this rulemaking does not address the
proposed enhanced monitoring requirements, however many of the comments mentioning
enhanced monitoring are pertinent to the CE rulemaking. EPA agrees that a change in the
compliance test can change the standard. However, EPA does not agree that the CE revisions
will redefine compliance in any way. These revisions merely allow EPA to use any information
to
prove that, if a test had been conducted, it would have documented a violation. For example, if
EPA attempts to use CE to show violations of the VOC surface coating requirements, the
particulate matter requirements, or the other standards mentioned by the commenters, the CE
must prove that a violation would have been shown had the reference method been used in
similar
circumstances.
1. Compliance Obligation -- Frequency of Testing
EPA rejects the argument put forth by some commenters that where a standard contains a test
method that is typically performed, at most, periodicially, the compliance obligation is periodic
as
well. As discussed in detail in Section III.D. of the final rule preamble, EPA finds the corollary
argument that testing sources subject to such standards at increased frequencies makes the
standard more stringent also to be without merit and unsupportable under the Act.
EPA also rejects the argument presented by one commenter that EPA must now determine
whether a standard was intended to require continuous compliance based on the data used to
support the standard. This commenter asserted that when EPA had limited data it established a
periodic compliance test and did not expect continuous compliance. Rather, according to this
commenter, "such standards provide for performance tests to be conducted relatively
infrequently." The commenter analyzed the data used as the basis for one such standard (Subpart
PPP of Part 60) and claimed this statistical analysis showed that the standard could not be met
continuously and under all conditions. The statistical arguments raised by this commenter
constitute an untimely attack on the standard and are not properly at issue in this rulemaking
since
it is not intended to change the requirements of any previously promulgated standards. Such
comments should have been presented at the time EPA took comment on the standard because
EPA made clear at that time that it was establishing a standard that could be met under all
conditions:
Based on the Agency's consideration of factors relevant to the level of controlled
emissions (e.g., product type, product density) and the results of the emission test
program, the Administrator has determined that the proposed emission limit is
achievable in all circumstances that can be reasonably foreseen.
49 FR 4590, 4596 (February 7, 1984); accord 50 FR 7694, 7697 (February 25, 1985) (final rule).
Further, consistent with this position, EPA did not specify that performance tests under this
standard could only be conducted infrequently. If these statistical arguments had been submitted
as a comment on that standard, their merit would have been considered in promulgating the
standard. The commenter claims that these type of comments were not submitted because EPA
employees routinely assured industry that standards did not have to be continually complied
with.
Such claims, however, do not square with the formal pronouncements of the Agency in
rulemaking document after rulemaking document that continuous compliance is required.
Examples of EPA's formal statements are collected below, and the following pertinent example
from Subpart S is discussed here.
Following the original promulgation of standards for Primary Aluminum Plants under Subpart S,
the aluminum industry filed a petition for review based on their assertion that the standard was
too stringent and could not be consistently complied with by modern, well-controlled facilities,
even though the original standard required only an initial performance test. In response, EPA
and
the industry conducted a test program at a new aluminum facility that reflected use of best
demonstrated technology. Based on the results, EPA agreed that there was inherent variability in
emissions that was not reflected in the database used to establish the standards. Based on a
statistical analysis of the test data, EPA determined that there was approximately an 8 percent
probability of a stack test exceeding the standard. Using different analytical methods, the
industry
petitioners estimated the probability would range from 2.5 to 10 percent. See "Primary,
Aluminum, Background Information: Proposed Amendments," U.S. Environmental Protection
Agency, EPA -450/2- 78-025a. August 1978; docket item OAQPS-78-ID-III-B-1. To address
the possibility that a test could show a violation because of inherent variability, the Agency
promulgated a revised standard that allowed a test to be above the generally applicable standard
by a specified amount if the source could document that it conducted exemplary O&M during the
conduct of the test. See 45 FR 44203 (June 30, 1980).
This example documents that where the industry can show that there is a significant probability
of
a test showing a violation because of inherent variability, EPA is willing to make the necessary
adjustments in the standard. Under the commenter's line of reasoning, EPA could have simply
responded that testing was to be conducted only infrequently under the original standard and
therefore the probability concern was already adequately addressed. This approach clearly was
not taken in this example.
The point that the frequency of performance testing can be altered without affecting the
stringency of a standard is also made in two examples where EPA has retroactively modified the
frequency of required compliance determinations without addressing stringency concerns. In the
revisions to Subpart S discussed above, EPA determined that there was evidence that sources
may
not be conducting proper operation and maintenance and that the rule therefore should be
modified to require monthly performance tests. The Agency further stated that it reserved the
authority to require even more tests if it believed additional tests to be necessary. See 45 FR
44203 (June 30, 1980). As originally promulgated, the standards did not require testing at any
specified frequency. In the preamble to the revisions, EPA stated that the selected frequency of
testing was "a judgmental compromise" between testing costs and the possibility of inadequate
maintenance. See id. at 44205. Nowhere did EPA suggest that the frequency would impact the
stringency of the standards or that the adjustment to the standard to address inherent variability
discussed above was necessitated by the increased frequency of tests.
Another example where EPA has retroactively increased compliance test frequency without
considering the stringency of the emission limit involves Subpart F. EPA added a requirement to
install a COMS for kilns and clinker coolers at all Portland cement plants subject to Subpart F.
See 53 FR 50354 (December 14, 1988). For units equipped with certain types of control
equipment involving either multiple stacks or a monovent, the COMS requirement is waived and
daily Method 9 testing is required. See id. at 50354-55. Because Method 9 is the required
compliance test, such data could be used to determine compliance; although not discussed in this
preamble, EPA has discussed this point in other standards with periodic Method 9 monitoring
requirements. See, e.g., the 1984 Subpart HH amendments, which allow lime manufacturing
plants with positive-pressure fabric filters to use daily Method 9 testing in lieu of a continuous
opacity monitoring requirement; in the final rule preamble, EPA states that, because Method 9 is
the opacity standard test method, the results of the daily tests "may be used to determine
compliance with the control device emission standard." 49 FR 18076, 18076-77 (April 26,
1984).
Commenters to the Subpart F amendments argued that the COMS and Method 9 requirements
were illegal as applied to existing facilities because NSPS cannot be applied retrospectively.
EPA
disagreed and stated that the authority for the action was EPA's general authority under section
114 to require monitoring and testing to evaluate compliance. The preamble concluded by
stating
that the "requirements do not change the standards of performance themselves." 53 FR at 50360.
Even if the commenters were somehow correct that NSPS and similar numerical emission limits
were meant to be complied with less than continuously, their conclusions regarding the
reasonableness of infrequent reference tests could not be correct. Suppose hypothetically that
EPA intended that a source comply with an emission standard only 95% of the time, and the
source was so complying. In these circumstances, any reference test that showed a violation --
even one conducted only once a year -- could be deemed unfair, arbitrary and capricious because
it might have caught the source during a period of "intended" exceedance.
Further, suppose that the source was meeting the standard less than 95% of the time -- for
example, 90% of the time, or 60%. Even in the commenters' view, this source would be in
violation. However, because the source would still be meeting the standard more than 50% of
the
time, EPA, the states or the public would have less than a 50% chance of detecting these
violations during any particular yearly reference test. Thus, far from ensuring fairness in
emission
limit compliance and testing, the commenters' scheme would effectively render even infrequent
reference tests potentially unfair and illegal, and would allow widespread, undisputed
noncompliance to go potentially undiscovered and unremedied. Moreover, such an approach
would loosen numerical emission standards adopted pursuant to previous notice and comment
rulemaking. EPA rejects this approach and its results.
As another example of anomalous results, in a pending enforcement action, a source conducted
only one Method 5 test run on its emissions whereas the reference test called for the average of
three such runs. The results of that one test were so much greater that the applicable emission
limit that even if the remaining two tests were zero, the source would still not have been in
compliance. The source may maintain that emissions violations can not be proven, since three
test
runs were not conducted. Thus, the source might be able to escape liability by its own failure to
complete the proper test, having seen the damaging results of the first run. Such anomalous
results will clearly not be permitted when this rulemaking is finalized.
Finally, EPA also rejects the suggestion that continuous compliance is only required where
longer
term averaging is used in test methods. Averaging emission rates over time is just one of several
different methods of assuring that a standard is set at a level that is achievable. Another method
is
to set the standard at a level higher than that expected during the short term test.
2. Compliance Obligation -- Compliance Under All Circumstances
As a corollary to commenters' claims that performance tests are intended to demonstrate only that
compliance with emissions standards can be achieved, they assert that continuous compliance
with
those standards increases their stringency, because EPA never intended the standards to be met
under conditions other than those under which the performance test was conducted. EPA
disagrees, because it is clear that performance tests are intended to represent the ability of a
source to comply over the full range of its normal operations.
As discussed in Section III.D., particularly III.D.1. of the final rule preamble, both the Act and its
implementing regulations require continuous compliance with emission limits. EPA has
previously made its position clear on this point in publicly available guidance: In the strict legal
sense, sources are required to meet, without interruption, all applicable emission limitations and
other control requirements, unless such limitations specifically provide otherwise. "Definition of
Continuous Compliance' and Enforcement of O&M Violations," issued by Kathleen M. Bennett,
Assistant Administrator for Air, Noise and Radiation, June 21, 1982 (cited as "O&M
Enforcement
Memorandum").
The NSPS general provisions require that performance tests be conducted "based on
representative performance of the affected facility." 40 CFR 60.8(c). The only operating
conditions explicitly excluded from representative conditions generally are startup, shutdown,
and
malfunction. 40 C.F.R. 60.8(c). All other expected operating conditions are representative. See
Stone Container Corp. v. EPA, No. 96-3479 (6th Cir. December 16, 1996) (unpublished
decision)
(rejecting facility's argument that representative conditions means historical average operating
conditions). EPA policy statements have also made clear that the term "representative" generally
is meant to cover all conditions other than those specifically excused by the general provisions or
the applicable standard:
Performance tests can only be conducted during periods of representative
operation of both the affected facility and the emission control system. All
conditions except start-up, shutdown and malfunction are considered
representative operation.
Memorandum from Don R. Goodwin, Director, Emission Standards and Engineering Division,
August 30, 1976 (emphasis added); this memorandum is included in the docket.
Accordingly, circumstances that regularly arise during the course of normal operations, even if
they result in higher emissions than exist during ideal operating conditions, are the responsibility
of the owner or operator and do not excuse compliance with specified emissions limits. For
example, EPA has opined with respect to the NSPS for electric utility generators that
soot-blowing periods, which cause higher particulate emissions, do not constitute an upset
condition
because they occur at regular intervals. Hence, the need to comply during such periods is not
excused. See "Restatement of Guidance on Emissions Associated with Soot-Blowing," issued by
Kathleen M. Bennett, Assistant Administrator for Air, Noise, and Radiation, May 7, 1982; this
guidance is available in the docket.
To take another example, 40 CFR 60.8(a) in the NSPS general provisions states that
demonstration of compliance with emissions limits is not required during a shakedown period
prior to conducting an initial performance test. The purpose of the shakedown period is to enable
the source owner or operator to identify and eliminate problems that would prevent it from
meeting the initial performance test and continuous compliance thereafter:
This "shake down" period provides a source with a limited time to work out maintenance
and operating problems in an effort to establish a normal course of operation which will
result in day-to-day compliance with the emission limitation.
Memorandum from Edward Reich, Director, Division of Stationary Source Enforcement, August
30, 1976; this memorandum is available in the docket.
The requirement of continuous compliance under all operating conditions except those that are
specifically excluded is demonstrated by various individual NSPS regulations where EPA has
established performance tests that are intended to reflect worst-case conditions, such that it is
reasonable to require compliance under all operating conditions. For example, in promulgating
standards for Phosphate Rock Plants (40 CFR Part 60, subpart NN), EPA responded to
comments that proposed particulate emission limits "were too stringent to be achieved on a
continuous basis" by revising the standard, because the Agency's evaluation "indicated that the
proposed emission limits could not be achieved continuously under all operating conditions
which
are likely to occur." 47 FR 16582, 16584 (April 16, 1982). EPA instead promulgated standards
based on the performance of best demonstrated technology "on the worst case uncontrolled
emission levels." 47 FR at 16585. Cf. 57 FR 57047, 57049 (December 2, 1992) (EPA notes a
deficiency in a SIP because it fails to require that "[s]tack test which are to be used to verify
compliance with emission limits must be conducted under worst-case conditions. . . .")
Likewise, in promulgating standards for Ferroalloy Production Facilities (Subpart Z), EPA
responded to comments that the proposed standards would not be "technically feasible at all
times" by noting that most of the cited examples related to malfunction conditions, under which
compliance was not required. See 41 FR 18498, 18500 (May 4, 1976). EPA provided a special
exception for one non-malfunction event, limits on visible emissions when a blowing tap occurs,
on the ground that compliance may not be achievable under such conditions. See 40 CFR
60.262(a)(5); 41 FR at 15800. With this exception, EPA concluded that the "standards are
achievable for all normal process operations at facilities with well-designed, well-maintained,
and
properly operated emission collection systems." 41 FR at 18500.
As discussed above, the general rule is that testing can be performed under the full range of
representative conditions at a source and that compliance is required except where specifically
excused. However, there are some emissions standards containing specified test methods that
dictate performance tests only under certain conditions where it is clear from the rule and
supporting documentation that compliance with the stated limits is not expected under other
conditions. These limitations on the applicability of test methods reflect limitations on the
ability
of even well-controlled sources that are properly operated and maintained to comply with stated
limits under certain conditions. Where specified test methods for particular standards plainly
evidence an intent that the standard itself does not cover certain operational modes that are still
within the normal range (as opposed to those that fall within periods of startup, shutdown, and
malfunction where the requirement for compliance with stated limits is excluded by rule),
compliance with stated limits is simply not required under such operational modes. For example,
in promulgating standards for granular triple superphosphate storage facilities (Subpart X), EPA
specified that due to the increased difficulty in meeting the standards with only partially filled
buildings, performance tests must be performed when the amount of product exceeds 10 percent
of the building's capacity and fresh product (as defined in the regulations) is at least 20 percent of
the total or, in some cases, 5 days capacity. See 40 CFR 60.244(a); 40 FR 33152, 33153 (August
8, 1975).
One commenter submitted as part of its comments a chart purporting to show higher NOx
emission concentrations, in pounds per MMBTU, at low load conditions in a single coal-fired
boiler "with LNCFS Level 3 Controls." The controls referred to by the commenter are low Nox
burners incorporating separated overfire air. See 60 FR 18751, 18752 (1995) (defining LNCFS
3). While this chart was submitted ostensibly to show that it is impossible to comply with the
relevant emission standard under all conditions, EPA does not believe that it demonstrates this
point. First, it is inappropriate to rely on data from a single, unidentified source to support a
position regarding the ability of a category of sources to meet emission standards. In addition,
the
chart indicated that hourly data points were charted whereas if these hourly data points were
averaged over the appropriate averaging time many of the higher data points may have been
reduced. Likewise, there was no indication that excused periods of operation, such as startup,
shutdown and malfunction were eliminated from the charted data points. Therefore, it may be
that the unnamed source was in complete compliance during the relevant period. Then, too,
another recent study of 53 boilers, prepared by US EPA's Acid Rain Division and the Cadmus
Group, suggests that there may not be a strong, if any, NOx-load relationship. See Docket
A-95-28, Item IV-A-6.
Regarding the cited example of the Clean Water Act, under which the NPDES allowed for 1%
deviations when continuous monitoring was required (see 40 CFR 401.17), this example
supports
EPA's contention that where the Agency intends to allow less than 100% compliance, an
appropriate allowance is put in the standard. EPA knows how to allow for periods of exception
and has provided for them in some standards. Thus, where no such allowances are specified, this
means that continuous compliance is required.
3. Specific Standards
Also, as discussed in section III.D. of the final rule preamble, EPA has reviewed numerous NSPS
and NESHAP examples to document that the standards are intended to be achieved at all times
except as may be provided for in excused periods explicitly included in the standards. The
following discussion details the findings of that review. The Agency first discusses NSPS
Subparts BB and D and NESHAP Subpart O because of the focused comments received on these
particular standards. The Agency then discusses additional standards that clarify the nature of a
source's continuous compliance obligations.
Subpart BB. Certain commenters used Subpart BB as an example to document that standards are
not intended to apply on a continuous basis. A coalition group used as an example the
establishment of an excess emissions allowance for opacity limits for recovery furnaces, such
that
readings above the stated limit would not be considered violations if they did not exceed six
percent of the total operating hours for the facility during a quarter. See 40 CFR 60.284(e)(1)(ii).
The commenters are incorrect, however, in asserting that the CE revisions will result in excess
emissions below the specified six percent allowance being considered violations of the NSPS
opacity limit. As discussed in the final rule preamble, particularly sections III.A. and III.D., the
CE revisions are not intended to change the stringency of any underlying emission limitations or
standards. Implementation of the CE revisions will not result in deletion of the six percent
opacity
exceedance allowance. Rather, that excess emissions allowance is an integral part of the NSPS
and must be taken into account in determining compliance at sources covered by that standard.
The EPA also clarifies today that any other excess emissions allowances approved or
promulgated
by EPA as part of any applicable requirement must be taken into account in determining
compliance at affected sources. In Subpart BB, for example, EPA also promulgated an excess
emissions allowance of one percent for total reduced sulfur (TRS) emissions from recovery
furnaces. See 40 CFR 60.285(e)(1)(i). This provision must be accounted for in determining
continuous compliance with the TRS emission limit. This provision of Subpart BB further
reinforces the Agency's position that allowances for exceedance of stated limits are limited to
those specified on the face of emission standards. Indeed, in promulgating the TRS excess
emissions allowance for recovery furnaces, EPA expressly acted to address "unavoidable normal
variability in the operation of a kraft pulp mill." 43 FR 7568, 7571 (February 23, 1978).
Likewise, in the original promulgation of standards in Subpart BB, EPA withdrew a proposed
excess TRS emissions allowance for lime kilns, deciding instead to raise the emission limit from
5
ppm to 8 ppm to account for variability in operations. Id. Additionally, in the final preamble to
revisions to Subpart BB, EPA made clear that continuous compliance with the standards is
expected. EPA discussed the degradation of ESPs and noted that with respect to a nine-year-old
ESP one commenter stated that "the data show that, even with maintenance, the ESP is not
capable of achieving NSPS consistently." The EPA responded that "It is the Agency's judgment
that this unit could consistently achieve the NSPS if the frequency of maintenance were
increased." 51 FR 18538, 18541 (May 20, 1986). Also, in discussing the achievability of the
standards for smelt dissolving tanks, the Agency discussed the fact that commenters had claimed
that "the ranges in their TRS monitoring data were indicative that the proposed standard cannot
be met on a consistent basis" (even though such monitors were not the compliance test method).
In response to this concern, EPA revised the existing TRS standards for smelt dissolving tanks
from 0.0084 g TRS per kg of black liquor solids to 0.016 g TRS/kg BLS "in order that all
facilities using BDT can meet the TRS standard." Id. at 18542. In contrast, EPA declined to
revise the standard for lime kilns even though several commenters argued that the existing TRS
standard needed to be revised to reflect the results of continuous monitoring data. Based on
these
concerns, EPA analyzed additional TRS CEM data to consider if the standard needed to be
revised. EPA concluded that the "data from these 3 facilities indicate that the NSPS can be
achieved when [best demonstrated technology (BDT)] is implemented." Id. at 18543. The
Agency noted further that, although "industry continues to believe it is possible" that periods of
excess emissions could occur when employing BDT, "the Agency has not received any data
which
would indicate that such is the case." Id. These actions rebut industry claims that EPA did not
expect compliance with stated emission limits at all times, except as may be provided on the face
of the regulations. Furthermore, these actions demonstrate that if EPA accepts that a certain
standard cannot be achieved "consistently", it will adjust that standard accordingly.
The Agency notes that the Subpart BB preamble and background documents discuss that excess
emissions are not violations because compliance is determined only by performance tests. The
CE
revisions will modify these prior Agency statements so that excess emissions may be considered
violations where those excess emissions can be compared to the results that would be provided if
a performance test were conducted during the same relevant time period. As discussed in
Section
III.D.5. of the final rule preamble, EPA believes that this modification in its prior statements and
policies in this regard is warranted and permissible under the Act.
Subpart D.
a. Proposed Amendment of Subpart D
In support of their argument that the CE revisions will increase the stringency of underlying
standards, electric utility industry commenters point to a 1983 proposal by EPA, which was
never
finalized, to revise Subpart D by requiring use of CEMS or fuel sampling and analysis instead of
stack tests to determine compliance with SO2 emission limits, and to establish an averaging time
consisting of a 30-day rolling average. See 48 FR 48960 (October 21, 1983). These commenters
claim that this proposal would have changed the nature of the compliance obligation from an
obligation to comply only when infrequent stack tests were performed to a continuous
compliance
obligation. (The utility commenters also point to the NOx and particulate matter standards in
Subpart D as not requiring continuous compliance.) They argue that the proposal supports this
notion, citing a statement in the EPA proposal that a 30-day averaging time would not make the
existing Subpart D more stringent. See 48 FR at 48961. Hence, they argue, the CE revisions
will
render Subpart D more stringent by allowing continuous determinations of compliance in a
manner consistent with the performance test specified in Subpart D, which provides for the
averaging of 3 one-hour test runs, or a 3-hour average.
The principal stated reason for EPA's proposal to adopt a 30-day rolling average was to respond
to concerns that short-term variability in fuel sulfur content and control device performance --
and
hence, in emissions -- had not been well understood in 1971 when the standard was adopted and
was not appropriately addressed by a 3-hour compliance test. The proposed 30-day average
would enable a larger percentage of the nation's coal supply to be used as "compliance coal" to
meet the standards, and also would reduce the effects of coal sulfur variability on those sources
utilizing flue gas desulfurization (FGD) control technology to meet the standards. See Id. The
EPA also stated that the proposed revisions would make Subpart D consistent with what it
characterized as the intent and anticipated effect at the time of original promulgation regarding
available coal supplies, and "does not make it a more stringent regulation with which to comply."
Id.
The EPA disagrees that the CE revisions will render Subpart D more stringent. Rather, the
utility
industry commenters have misconstrued the meaning and impact of Subpart D and EPA's 1983
proposed revisions in several respects. First, Subpart D has always required continuous
compliance and the 1983 proposal did not imply anything to the contrary. Second, while the
commenters are correct that EPA noted that adopting a 30-day averaging time would affect the
stringency of the standard, that effect on stringency was related to the change in averaging time,
itself, and not to any change in the continuous nature of the compliance obligation. In fact, most
of the discussion of stringency in the 1983 proposal related to concerns with the stringency of
Subpart D as written and supports EPA's position that continuous compliance is required under
Subpart D. These points are addressed below.
Utility industry commenters wrongly assert that continuous compliance with Subpart D is not
already required. Consistent with the balance of the NSPS program and with emission
limitations
under the Clean Air Act generally, EPA acknowledged as to Subpart D that continuous
compliance was necessary in the 1983 Subpart D proposal. The EPA proposed to require
continuous monitoring for compliance determination purposes as part of the 1983 proposal
because "it will better ensure that sources continuously comply with the standard." 48 FR at
48961 (emphasis added). The Agency's attorneys recommended that the quoted preamble
language be used in place of earlier draft language, because the earlier draft "incorrectly implies
that sources subject to NSPS's that do not require continuous compliance testing are not required
to comply continuously." See Memorandum from Earl Salo, Attorney, Office of General
Counsel, to Bob Ajax, Chief, Standards Development Branch (March 23, 1983) ("Salo
Memorandum") attached to Memorandum from William F. Pedersen, Jr., Acting Associate
General Counsel, to Courtney M. Price, Acting Associate Administrator and General Counsel
(March 31, 1983) ("Pedersen Memorandum"); these memoranda are included in the docket.
EPA's discussion of the stringency of its proposal is in no way inconsistent with this continuous
compliance regime. In fact, the opposite is true. EPA's recognition that the proposed change in
averaging time would make Subpart D less stringent is necessarily based on the premise that
continuous compliance was required under the existing standard. If subpart D, as promulgated,
did not require continuous compliance, then changing to a continuous compliance regime might
very well have had the effect of making the standard more stringent. However, EPA was careful
to make clear that the proposed changes to Subpart D did not make it more stringent, rather, EPA
believed that the original standard was too stringent because EPA, in establishing that standard,
had failed to consider emission variability. Thus, the proposed changes to subpart D, while they
arguably may have conformed the standard to the original intent of the existing standard, actually
made the standard, itself, more lenient. The reason the proposed standard was more lenient was
because the averaging time was being extended while the mass emission rate was being held
constant. Over longer averaging periods it is more likely that a test will monitor the full range of
emission variability rather than possibly capture only peak emissions.
Again, EPA's attorneys were clear in describing the intent and effect of the proposed change:
The effect of the change from a 3-hour averaging time to a 30-day averaging time
is to make the standard more lenient, since it reduces the need to preserve a margin
of safety against short-term peaks in SO2 emissions caused by variations in the
sulfur content of coal. The preamble states that this change is justified because in
1971 EPA did not understand sulfur variability in coal and set a standard that was
more restrictive than intended. EPA meant to set a standard that about a quarter
of the coal in the country would be clean enough to meet without scrubbing, but,
in fact, set a standard that only five to ten percent of the coal can meet without
scrubbing. The amendment, then, is needed to bring us back to the original intent.
Pedersen Memorandum. Thus, although it may have been EPA's underlying intent in 1971 to
provide for a higher percentage of compliance coal, that intent obviously was not reflected in the
promulgated standards. Industry commenters are mistaken, therefore, in criticizing the CE
revisions as increasing the stringency of Subpart D. Their complaint is properly addressed to the
terms and provisions of that NSPS as originally promulgated, or to the never-completed 1983
proposed changes, that would have relaxed Subpart D, and is not at issue in this rulemaking.
b. Comparison of Subparts D and Da
Utility industry commenters also assert that a comparison of Subpart D and the 1979 Subpart Da
NSPS applicable to new utility units constructed after 1978 demonstrates, through consideration
of anthracite-burning units, that interpreting Subpart D as requiring short-term compliance makes
it more stringent. The essence of this argument is that in the case of units burning anthracite
coal,
Subpart Da did not alter the 1.2 lb/mmBtu SO2 emission standard applicable to all coals under
Subpart D, but did add a 30-day averaging time and required continuous monitoring. Hence,
they
argue, interpreting Subpart D as requiring continuous, short-term compliance renders Subpart Da
less stringent than Subpart D due to coal sulfur variability, when EPA must have intended
Subpart
Da to be more stringent, or at least as stringent, as the earlier Subpart D standard.
Once again, EPA disagrees. The percent reduction requirement in Subpart Da was the primary
emphasis in the Subpart Da rulemaking and, as explained below, that is the regulatory
requirement
that has the most impact on the stringency of the 1979 Subpart Da standards, taken as a whole.
The Agency recognized that the exemption provided for anthracite-fired units would mean that
such units would be subject to less stringent regulation than other Subpart Da units, but that the
approach was justified because of the potential environmental benefits associated with
encouraging the use of anthracite (particularly mine reclamation). See 44 FR 33580, 33590
(June
11, 1979). Therefore, it would be inappropriate to analyze anthracite-fired units as part of a
comparison of the relative overall stringency of Subpart D versus Subpart Da. Further, the fact
that anthracite-fired units are exempt from the percent reduction requirement is of little or no
practical significance. Few, if any, utility units subject to any NSPS burn anthracite coal, which
is
little used today. Based on a review of the 1994 edition of the "Environmental Directory of US
Powerplants," a publication prepared by the Edison Electric Institute, it appears that only six
utility units in the U.S. (all located in Pennsylvania) use anthracite fuel (the units are Holtwood
17, Sunbury 1-4, and Hunlock 3) and none of the six are NSPS units. (See the docket for a copy
of the relevant portions of this publication.) Therefore, the emission standard for Subpart Da
units burning anthracite coal does not support the assertion that continuous, short-term
compliance with emission limits is generally not required.
Regarding the percentage reduction requirement in Subpart Da, it is clear that the impact
of that provision on SO2 emissions from bituminous coal is by far the most important difference
in
the effective stringency of the SO2 emission limits as between Subparts D and Da. Under
Subpart
Da, covered sources must reduce sulfur dioxide emissions by 70 to 90 percent, depending on the
sulfur content of the coal being fired, in addition to complying with a 1.2 lb/mmbtu nominal
emission rate. In practice, given the sulfur content of coals actually fired, the percentage
reduction requirement, which necessitates the use of flue gas desulfurization equipment ("FGD"),
or "scrubbers," greatly outweighs any impact of a longer averaging time in assessing the overall
stringency of S