National Emission Standards for Hazardous Air Pollutants for Source Category: Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry and Other Processes Subject to the Negotiated Regulation for Equipment Leaks; Determination of MACT ``Floor''

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[AD-FRL-4892-5]

National Emission Standards for Hazardous Air Pollutants for

Source Category: Organic Hazardous Air Pollutants From the Synthetic

Organic Chemical Manufacturing Industry and Other Processes Subject to

the Negotiated Regulation for Equipment Leaks; Determination of MACT

``Floor''

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: On December 31, 1992, the EPA proposed standards to regulate

the emissions of certain organic hazardous air pollutants from

synthetic organic chemical manufacturing industry (SOCMI) production

processes and seven other processes which are part of major sources

under section 112 of the Clean Air Act as amended in 1990 (the Act).

This rulemaking is commonly called the Hazardous Organic NESHAP or the

HON. In the final action regarding the December 31, 1992 proposal,

which was signed on February 28, 1994, and published in the Federal

Register on April 22, 1994, EPA deferred taking final action regarding

provisions applicable to medium storage vessels due to the need to

resolve an issue of statutory interpretation of section 112(d)(3)(A) of

the Act. On March 9, 1994, EPA reopened the comment period to request

additional comment on the appropriate interpretation of this statutory

provision and the effect of that interpretation on the appropriate

control requirements for medium storage vessels at facilities subject

to the HON.

This action announces EPA's final decision regarding the

interpretation of Clean Air Act section 112(d)(3)(A) for purposes of

the HON and the final decision regarding control provisions applicable

to medium storage vessels in SOCMI facilities subject to the HON. The

decision announced in this action regarding the interpretation of Clean

Air Act section 112(d)(3)(A) for purposes of the HON will be

presumptively followed in subsequent MACT rulemakings, but it will not

be binding. Although EPA believes that Congress intended one

interpretation--referred to as the ``Higher Floor Interpretation''--in

Clean Air Act section 112(d)(3)(A), EPA also believes that the Agency

retains discretion in important respects in setting Floors for MACT

standards. EPA intends to exercise its discretion, within the statutory

framework, to promulgate MACT standards that best serve the public

interest.

EFFECTIVE DATE: June 6, 1994.

See Supplementary Information section concerning judicial review.

ADDRESSES: Dockets. The following dockets contain supporting

information used in developing the proposed provisions. Docket Number

A-90-19 contains general information used to characterize emissions and

control costs for the industry and Docket A-90-21 contains information

on storage vessels. These dockets are available for public inspection

and copying between 8 a.m. and 4 p.m., Monday through Friday, at the

EPA's Air and Radiation Docket and Information Center, Waterside Mall,

room M1500, 401 M Street SW., Washington, DC 20460. A reasonable fee

may be charged for copying.

FOR FURTHER INFORMATION CONTACT: On technical issues, Dr. Janet S.

Meyer, Standards Development Branch, Emission Standards Division (MD-

13), U.S. Environmental Protection Agency, Office of Air Quality

Planning and Standards, Research Triangle Park, North Carolina 27711,

telephone number (919) 541-5254. For further information on the legal

issue addressed in this notice, contact Michael S. Winer, Assistant

General Counsel, Air and Radiation Division (2344), Office of General

Counsel, Environmental Protection Agency, 401 M Street SW., Washington,

DC 20460, telephone number (202) 260-7606.

SUPPLEMENTARY INFORMATION:

Judicial Review

Under section 307(b)(1) of the Clean Air Act (CAA), judicial review

of the actions taken by this document is available only on the filing

of a petition for review in the U.S. Court of Appeals for the District

of Columbia Circuit within 60 days of today's publication of this rule.

Under section 307(b)(2) of the CAA, the requirements that are subject

to today's document may not be challenged later in civil or criminal

proceedings brought by EPA to enforce these requirements.

Public Comment: Approximately 55 comment letters were received in

response to the March 9, 1994 (59 FR 11018) reopening of the comment

period. The majority of these letters were from industries or

industrial trade associations, arguing in favor of the less stringent

``Lower Floor Interpretation.'' Environmental groups, State or local

governments and labor unions argued almost uniformly in favor of the

more stringent ``Higher Floor Interpretation.'' The EPA considered all

public comments in framing the final policy for MACT floor

determination and in selection of the requirements for medium storage

vessels. The major issues raised by the comments are addressed in this

preamble. The EPA's responses to all the comments can be found in

docket A-90-19, Subcategory VI-B.

I. Summary of Decision on MACT Floor Determination

This section describes EPA's decision with respect to the

interpretation of Clean Air Act section 112(d)(3)(A) for purposes of

this rulemaking. As set forth in more detail below, EPA believes that

one of the interpretations of section 112(d)(3)(A)--referred to as the

``Higher Floor Interpretation''--is the better and more natural reading

of the statutory language.

A. Background

Section 112(d)(3) of the Clean Air Act provides that Emissions

standards promulgated under this subsection for existing sources * * *

shall not be less stringent * * * than--

(A) The average emission limitation achieved by the best performing

12 percent of existing sources * * * 42 U.S.C. section 7412(d)(3).

Existing sources for which the Administrator lacks emissions

information and those that have recently achieved LAER are excluded

from consideration. Id. (For categories or subcategories with fewer

than 30 sources, standards may not be less stringent than ``the average

emission limitation achieved by the best performing 5 sources.'' CAA

section 112(d)(3)(B)). The minimum level of stringency defined by this

language has come to be known as the MACT Floor.

In the March 9, 1994 Federal Register, EPA published a notice

soliciting comment on ``the appropriate interpretation of'' section

112(d)(3)(A). Two interpretations of section 112(d)(3)(A) were

discussed. Under the first, referred to as the ``Higher Floor

Interpretation,'' EPA would look at emission limitations achieved by

each of the best performing 12 percent of existing sources, and average

those limitations. ``Average'' would be interpreted to mean a measure

of central tendency such as the arithmetic mean or median. (The

arithmetic mean of a set of measurements is the sum of the measurements

divided by the number of measurements in the set. The median is the

value in a set of measurements below and above which there are an equal

number of values, when the measurements are arranged in order of

magnitude).

Under the second, ``Lower Floor Interpretation,'' EPA would look at

the average emission limits achieved by each of the best performing 12

percent of existing sources, and take the lowest. This second

interpretation groups the words ``average emission limitation'' into a

single phrase, and asks what ``average emission limitation''

(accounting for variability over time, or between different pollutants

being emitted from a facility) is ``achieved by'' all members of the

best performing 12 percent.

B. EPA's Interpretation of Section 112(d)(3)(A)

The EPA believes that the ``Higher Floor Interpretation'' is a

better reading of Clean Air Act section 112(d)(3)(A) than the ``Lower

Floor Interpretation.'' This conclusion is based on a review of the

statute, legislative history and comments received in response to EPA's

March 9 notice.

1. The Statutory Language

Section 112(d)(3)(A) requires that standards be no less stringent

than ``* * * the average emission limitation achieved by the best

performing 12 percent of existing sources * * *''. The EPA believes

that the most natural and straightforward reading of this language

would have EPA first determine the emission limitations achieved by

sources within the best performing 12 percent, and then average those

limitations. This is the method described above as the ``Higher Floor

Interpretation.''

The EPA believes that if Congress had intended the Lower Floor

Interpretation, language other than that actually used in section

112(d)(3)(A) would have been far more natural. For example, Congress

could easily have expressed the Lower Floor Interpretation by requiring

standards to be no less stringent than ``the emission limitation

achieved by all sources within the best performing 12 percent.''

Similarly, Congress could have required standards to be no less

stringent than ``the average emission limitation achieved by the worst

performing member of the best performing 12 percent,'' or ``the

emission limitation (averaged over time to take account of variability

in the effectiveness of control) achieved by all sources within the

best performing 12 percent.'' Any of such phrases would have been a

more natural way to convey the Lower Floor Interpretation than the

language Congress chose. However, the actual language of section

112(d)(3)(A) provides, in straightforward fashion, that standards may

be no less stringent than the ``average emission limitation achieved by

the best performing 12 percent * * *''. To glean the Lower Floor

Interpretation from this language is a strain; words and concepts not

set forth in the statute must be added or inferred.

The language of section 112(d)(3)(B) makes this point even clearer.

That section requires that standards for existing sources in categories

or subcategories with fewer than 30 sources be no less stringent than

The average emission limitation achieved by the best performing

5 sources * * *

42 U.S.C. 7412(d)(3)(B). If an interpretation parallel to the Lower

Floor Interpretation were intended, it would have been more natural for

this provision to read ``the emission limitation achieved by the 5th

best performing source.''

2. The Legislative History

The legislative history lends strong support to the view that, in

passing section 112(d)(3)(A), Congress intended the Higher Floor

Interpretation.

On the House side, the language that would eventually become

section 112(d)(3)(A) was offered as a compromise amendment by Rep.

Dingell on the House Floor on May 23, 1990. (The language of the

amendment was identical to section 112(d)(3)(A) as ultimately enacted

into law; only the numbers were different). Rep. Dingell yielded time

to Rep. Collins ``for purposes of explaining the amendment.''

Legislative History of 1990 CAA Amendments at 2896. In doing so, Rep.

Collins noted that she had originally supported slightly more stringent

numbers than those included in the amendment, and that under her

original proposal

The average of emissions from the 10 percent cleanest sources

would be the MACT standard. In cases where there are less than 30

sources in a category or subcategory, the average of the 3 cleanest

sources would determine the standard.

Id. She went on to explain that under the compromise amendment

introduced by Rep. Dingell

MACT for existing stationary sources would be the average of the

best 15 [percent] of technologies within each category or

subcategory. For categories or subcategories where there are less

than 30 sources, the standard is based on the average emissions from

the best performing 5 sources.

Legislative History of 1990 CAA Amendments at 2897.

Rep. Collins' formulations are consistent with the Higher Floor

Interpretation, not the Lower. The ``average of the 3 cleanest

sources'' cannot mean, as the Lower Floor Interpretation would require,

the level of control achieved by all three of the ``cleanest sources.''

Nor can the ``average of the best 15 [percent] of technologies'' mean a

technology as good as that used by all sources within the top 15

percent.

Another discussion of section 112(d)(3) is similar. On October 27,

1990, Sen. Durenberger (a principal supporter of the Clean Air Act

Amendments) explained the provision on the Senate floor. His

explanation was as follows:

The standard may not be less stringent than the average of the

emission levels achieved by the best performing 12 percent of the

existing sources within the category* * * The Administrator is to

exclude from the calculation of the average of top 12 percent any

source which met the following conditions* * *

Legislative History of 1990 CAA Amendments at 870 (Cong. Rec. S16929--

Oct. 27, 1990). The second sentence of Sen. Durenberger's statement, in

particular, is inconsistent with the Lower Floor Interpretation. Sen.

Durenberger makes clear that the ``average'' called for in the statute

is of the ``top 12 percent,'' not the emission limitations achieved

over time at each individual source.

No legislative history was found that supports the Lower Floor

Interpretation. The EPA believes that the legislative history indicates

that individual legislators--including those central to the drafting of

section 112(d)(3)--understood the word ``average'' to mean that once

the emission limitations achieved by the best performers in a category

had been determined, those results should be averaged. This is the

method of the Higher Floor Interpretation, not the Lower.

3. Issues Raised in Public Comment

a. Arguments Concerning the Statutory Language.

(i) Plain Meaning of the Statute. Several commenters argued that

the meaning of the statute was plain on its face and that Congress

clearly intended the Higher Floor Interpretation. These commenters

argued that when section 112(d)(3)(A) is read as a whole in its most

natural way, the Congressional intent in favor of the Higher Floor

Interpretation is clear. They argued that if Congress had intended the

Lower Floor Interpretation, it would have used different language in

the statute.

The EPA agrees with these comments. As set forth in greater detail

above, EPA believes the plain statutory language strongly favors the

Higher Floor Interpretation.

(ii) Congress' Failure to Use the Words ``of the''. Several

commenters argued that if Congress had meant the Higher Floor

Interpretation, it would have added the words ``of the'' to the

statute, so that section 112(d)(3)(A) would read ``the average of the

emission limitations achieved by the best performing 12 percent.''

These commenters saw the absence of the words ``of the'' in the statute

as evidence that Congress intended the Lower Floor Interpretation.

The EPA agrees that the statute would be more clear if Congress had

used the words ``of the,'' but disagrees with the conclusion drawn by

these commenters for two reasons. First, standard English usage often

permits dropping the prepositions ``of the'' without changing the

meaning of a phrase. (For example, ``the biggest mountain in North

America'' has the same meaning as ``the biggest of the mountains in

North America.'' ``Best singer in the band'' has the same meaning as

``best of the singers in the band.'') The same cannot be said, however,

for the various phrases and concepts that must be read into section

112(d)(3)(A) in order to arrive at the Lower Floor Interpretation.

Phrases like ``the worst performing member of...'' or ``averaged over

time...'' simply are not dropped as part of standard English. Their

absence from section 112(d)(3)(A)--unlike the absence of the words ``of

the''--must be considered significant in interpreting the provision.

Second, although the words ``of the'' do not appear in section

112(d)(3)(A), they were used by key legislators in summarizing that

section prior to passage of the 1990 Clean Air Act Amendments. As noted

above, when Sen. Durenberger (a principal supporter of the Clean Air

Act Amendments) spoke on the Senate floor on October 27, 1990, he

explained section 112(d)(3)(A) as follows:

The standard may not be less stringent than the average of the

emission levels achieved by the best performing 12 percent of the

existing sources within the category* * *

Legislative History of 1990 CAA Amendments at 870 (Cong. Rec. S16929--

Oct. 27, 1990) (emphasis added). As also noted above, when Rep. Collins

introduced the provision in the House, she described it as follows:

The average of emissions from the 10 percent cleanest sources

would be the MACT standard. In cases where there are less than 30

sources in a category or subcategory, the average of the 3 cleanest

sources would determine the standard.

Legislative History of 1990 CAA Amendments at 2896 (emphasis added)

(describing a provision with identical language but different numbers

than the one ultimately enacted into law).

In EPA's view, the fact that Congress did not use the words ``of

the'' in section 112(d)(3)(A) is fully consistent with standard

English. However, the fact that key legislators did use these words in

describing the provision to their colleagues, in combination with the

failure of those legislators to use the phrases on which the Lower

Floor Interpretation depends, provides a strong indication that

Congress intended the Higher Floor Interpretation in enacting section

112(d)(3)(A).

(iii) Purpose of the Word ``Average''. Several commenters argued

that the word ``average'' in section 112(d)(3)(A) should be read to

require averaging not of emissions from different sources within the

top 12 percent, but instead of emissions from individual sources at

different times, or from different emission points, or made up of

different HAP. The EPA does not agree that the word ``average'' in

section 112(d)(3)(A) can reasonably be read to serve this purpose.

First, such a reading is difficult, if not impossible, to reconcile

with the provision of section 112(d)(3) establishing a ``floor'' for

new sources. Under those provisions, new source standards may not be

less stringent than

The emission control that is achieved in practice by the best

controlled similar source.

42 U.S.C. 7412(d)(3). Notably, Congress did not use the word

``average'' in this provision. If the word ``average'' in section

112(d)(3)(A) was intended to refer to averages across time, or between

emission points, or among different HAP, then Congress must have

intended that such averaging would take place for existing source

standards, but not for new source standards. There is no reason to

believe Congress intended this implausible result.

There is a much more likely explanation: That to the extent

Congress contemplated that averaging across time, or between emission

points, or among HAP would play a role in either existing or new source

MACT standards, it considered the terms ``emission limitation'' and

``emission control'' fully adequate to reflect that fact. In EPA's air

program, emission limitations have routinely been expressed in terms of

averages across time, for example, without any special statutory

direction or authority. There is no reason to believe that Congress

would have thought that special instructions were needed to ensure that

EPA continued this practice, and even less reason to believe Congress

would have thought special instructions were needed with respect to

existing source standards, but not new source standards.

Furthermore, the legislative history of section 112 casts doubt on

the interpretation of the word ``average'' offered by these commenters.

When Congress comprehensively revised section 112 in the Clean Air Act

Amendments of 1990, it based the revisions in substantial part on the

Clean Water Act's effluent guidelines program. (See, e.g., Remarks of

Sen. Durenberger, Cong. Rec. S516 (January 30, 1990) (``* * * this

approach to regulation of toxic air pollutants is not without

precedent. A program very similar to the one I have just described has

already been implemented under the Clean Water Act'').) Under that

program, certain limits (known as ``BPT limits'') have long been based

on the ``average of the best'' performance at existing facilities. (See

generally Remarks of Sen. Muskie, Legislative History of Federal Water

Pollution Control Act of 1972 at 169-70 (``The Administrator should

establish the range of `best practicable' levels based upon the average

of the best existing performance by plants of various sizes, ages and

unit processes.'')) In determining ``average of the best'' under the

Clean Water Act, EPA has historically identified the best performers in

an industrial category, and then averaged their performances. This

methodology is consistent with the Higher Floor Interpretation and not

the Lower.

(iv) Proximity of the Word ``Average'' to the Words ``Emission

Limitation''. Several commenters argued that the proximity of the word

``average'' to the words ``emission limitation'' suggests that

``average'' modifies ``emission limitation,'' and not the entire phrase

following those words. The EPA does not agree with this argument. In

English, adjectives often modify not only the noun immediately

following, but an entire phrase. In the phrase ``the biggest mountain

in North America climbed by members of the Washington, D.C. Climbing

Club,'' for example, the adjective ``biggest'' modifies the entire

remainder of the phrase. There is no reason to conclude that the word

``average'' in section 112(d)(3)(A) plays a different role.

(v) Use of the Words ``Achieved By''. Several commenters argued

that the use of the words ``achieved by'' in the statute indicates that

all sources within the top 12 percent must be achieving the emission

limitations used to set the MACT Floor.

The EPA does not agree with this argument. The EPA believes the

argument depends both on inferring the presence of the word ``all'' in

section 112(d)(3)(A), and (as discussed above) on ignoring, or

incorrectly construing, the meaning of the word ``average.'' Section

112(d)(3)(A) simply does not say ``the emission limitation achieved by

all sources within the best performing 12 percent* * *''. Congress' use

of the words ``achieved by'' cannot reasonably be stretched to

accomplish such a rewriting of the statute.

b. Arguments Concerning Structure of the Statute. Several

commenters argued that elements of the statute's structure support the

Lower Floor Interpretation. For example, some commenters argued that

the Lower Floor Interpretation best reflects EPA's authority to

consider cost and other factors in setting standards more stringent

than MACT Floor. Other commenters argued that the Lower Floor

Interpretation best reflects the distinction between existing source

MACT and new source MACT.

The EPA does not agree with these arguments. In fact, the Higher

Floor Interpretation fully preserves both of these structural elements

of the statute. With the Higher Floor Interpretation, just as with the

Lower, EPA still has authority to establish existing source standards

more stringent than the Floor based on enumerated criteria. With the

Higher Floor Interpretation, just as with the Lower, there is still a

distinction between the Floor for existing sources and the level of

control required for new sources. (Under section 112(d)(3), standards

for new sources must be at least as stringent as ``the emission control

that is achieved in practice by the best controlled similar source'').

The fact that there may be ``less distance'' to travel above the Floor

with the Higher Floor Interpretation does not establish an

inconsistency between that interpretation and other parts of the

statute, nor does it mean that the interpretation is flawed in any way.

Furthermore, structural arguments tend to favor the Higher Floor

Interpretation more strongly than the Lower. Section 112 was passed in

its current form to ensure quick and dramatic reductions in air toxics

emissions. Congress was frustrated with the slow pace of toxics control

prior to 1990, and many members in part blamed EPA for weak controls.

See, e.g., H. Comm. Rep. 101-490 at 150-54, 322-23; S. Rpt. 101-228 at

128-33. The structure and purpose of section 112 as a whole indicates

that section 112(d)(3)(A) was intended to establish a stringent minimum

level of control for hazardous air pollutants.

c. Additional Arguments. Several commenters argued that the Higher

Floor Interpretation would require EPA to set MACT Floors that failed

to correspond to real-world control technologies.

The EPA does not agree with this argument. The EPA believes that

the argument depends upon a flawed premise: That the word ``average''

can only mean ``arithmetic mean.'' In fact, there are a number of

conventional methods for determining the average of a data set,

including the median. Congress did not mandate a particular method of

determining ``average'' or central tendency in section 112(d)(3)(A),

and the choice of methodology--whether median, mean, or some other

measure--can often change the results markedly. For example, if the

five facilities that make up the top 12 percent of a source category

are achieving reductions equal to 99 percent, 98 percent, 95 percent,

94 percent and 93 percent, EPA need not set the MACT Floor equal to the

arithmetic mean of these values, which is 95.8 percent. Using the

Higher Floor Interpretation, EPA could set the MACT Floor equal the

median of these values, which is 95 percent.

This discussion responds to the most significant comments on legal

issues received in response to the March 9, 1994 Federal Register

document. Other comments on legal issues are addressed in item number

VI-B-61 in docket A-90-19.

C. Conclusion

The EPA believes that Congress spoke with clarity in section

112(d)(3)(A) of the Clean Air Act. That provision--requiring standards

to be no less stringent than ``the average emission limitation achieved

by the best performing 12 percent of existing sources''--lends little

support for an interpretation under which standards might be set at the

emission limitation achieved by the worst performing member of the best

performing 12 percent of existing sources. The legislative history

offers no support for such an interpretation, and indeed points

strongly in the opposite direction. The EPA believes that the Higher

Floor Interpretation represents the best reading of the statutory

language.

II. Discretion in Setting Floors for MACT Standards

In today's notice, EPA announces its conclusion that Congress

intended the Higher Floor Interpretation. The effect of this decision,

however, is not to identify any particular number (e.g. the 94th

percentile) as the Floor for all MACT standards. EPA retains discretion

in important respects in setting Floors for MACT standards, and intends

to exercise its discretion, within the statutory framework, to

promulgate MACT standards that best serve the public interest.

EPA believes the Agency retains substantial discretion, within the

statutory framework, to set MACT Floors at appropriate levels. For

example, because Congress did not define the term ``average'' in

section 112(d)(3), or in the legislative history, it implicitly

delegated the authority to EPA to do so. The choice of methodology--

whether mean, median, mode, or some other measure--can often change the

results. (The mean of a set of measurements is the sum of the

measurements divided by the number of measurements in the set. The

median is the value in a set of measurements below and above which

there are an equal number of values, when the measurements are arranged

in order of magnitude. The mode is the value that occurs most often in

a set of measurements). As some commenters noted, the ``average of the

best performing 12%'' corresponds to the 94th percentile when the word

``average'' is construed to be the ``median.'' If, however, ``average''

is construed to be the ``arithmetic mean'' or ``mode,'' a different

result may obtain. EPA construes the word ``average'' in section

112(d)(3) to authorize the Agency to use any reasonable method, in a

particular factual context, of determining the central tendency of a

data set. In addition, EPA has discretion to use its best engineering

judgment in collecting and analyzing the data, and in assessing the

data's comprehensiveness, accuracy and variability, in order to

determine which sources achieve the best emission reductions. EPA also

has discretion in determining how to analyze the data, and thus in

determining the appropriate ``average'' in each category or

subcategory.

There are other important ways that EPA retains discretion in

setting MACT floors. For example, Congress authorized EPA to

subcategorize source categories based on classes, types and sizes of

sources, which will result in different Floors for different

subcategories. CAA section 112(d)(1). Using this authority, EPA can

tailor standards to certain characteristics of particular emission

units and sources. EPA retains flexibility, for example, to conclude

that the production processes used at particular sources in the

relevant category are sufficiently different from processes used at

other sources in the same category to justify the creation of a new

subcategory.

These examples are not meant to be exhaustive. EPA has only begun

the process of setting MACT standards. As EPA gains experience in

setting MACT Floors, other issues may arise that will require EPA to

exercise its discretion in determining, for each case, what represents

the average emission limitation achieved by the best performing 12% of

existing sources (or the best performing five sources, in categories or

subcategories with fewer than 30 sources).

III. Precedential Impact of Today's Determination

In its March 9, 1994 document, EPA stated that ``the MACT floor

decision * * * in this rulemaking will have broad precedential effect,

and will be presumptively followed in subsequent MACT rulemakings.'' 59

FR 11018. Several commenters objected this statement, arguing that the

issue of how best to interpret section 112(d)(3)(A) should have been

addressed in a separate, generally applicable rulemaking.

The EPA wishes to emphasize that, although today's decision

concerning the interpretation of Clean Air Act section 112(d)(3) for

purposes of the HON will be precedential for future rulemakings, it

will not be binding. Specifically, EPA will fully consider all comments

on individual MACT standards, including those regarding the proper

interpretation of the language in sec. 112(d)(3)(A), received on or

before the close of the comment periods for those standards.

IV. Application of MACT Floor Decision to Medium Storage Vessels at

Facilities Subject to the HON

As described in the March 9, 1994 Federal Register reopening the

comment period, EPA requested comment on whether the control

requirements for medium storage vessels previously proposed by EPA

would be appropriate in the event those proposed controls were to be

determined to be more stringent than the floor. Only four commenters

addressed the question of the appropriate controls requirement for

medium storage vessels and provided rationale for their opinions. Of

these commenters, only one submitted information which purported to

represent control information for SOCMI storage vessels. This

information was reviewed and found to not provide any information on

control performance and to represent storage vessels associated with

non-SOCMI processes (i.e., other source categories) as well as SOCMI

processes. Therefore, the submitted information could not be used to

revise the database. The EPA review of this information is contained in

item VI-B-62 in docket A-90-19. This section of the preamble,

therefore, only presents the basis for the final decision on control

requirements for medium sized storage vessels.

For medium vessels, about 8 percent of the vessels are controlled

with either a 90-percent efficient control device or an IFR or EFR with

a continuous seal. All of the controlled medium-sized vessels contained

liquids with vapor pressures of 13.1 kPa (1.9 psia). Because the

arithmetic mean characteristics of the top 12 percent of the medium

vessels would not represent the performance of any known technology,

the EPA used the median as the average for these vessels. Thus, for

medium-sized storage vessels, the floor determined by the average

characteristics of the top 12 percent of the sources would require

control of vessels storing liquids with vapor pressures of 13.1 kPa

(1.9 psia) by either a 90-percent efficient control device or an IFR or

EFR with a continuous seal.

In selection of the control provisions for medium-sized storage

vessels, EPA considered the regulatory alternatives that were presented

in the April 22, 1994 Federal Register document. These alternatives

reflected a combination of: (1) The floor control for medium-sized

storage vessels, which at the time of proposal, were equipped with the

floor controls and (2) the proposed control provisions for medium-sized

storage vessels which were equipped with no control or less efficient

controls than the performance of the revised floor component for the

source-wide floor. The EPA did not develop a regulatory alternative

corresponding to application of the revised floor control level to all

storage vessels. Such an alternative would have essentially the same

control costs as the proposed control provisions, but would result in a

lower emission reduction. Because the floor control would represent a

less economically efficient option and would add to the complexity of

the rule, this option was not formally evaluated.

For medium storage vessels at existing sources, control at the

regulatory alternative used to represent the floor control was

estimated to cost $2.4 million/yr and to result in an emission

reduction of 370 Mg/yr (110 tons/yr). The regulatory option for control

level beyond the floor component is estimated to further reduce

emissions by less than 100 Mg/yr (110 tons/yr) at an additional cost of

$4 million/yr, or $48,000/Mg for each additional Mg of emission

reduction. Due to the relatively high incremental costs and low

emission reductions of this alternative, the EPA believes that the

control level for the medium storage vessels component of the source-

wide floor represented the maximum reduction achievable considering

cost and other impacts.

IV. Administrative Requirements

A. Docket

The docket is an organized and complete file of all the information

submitted to or otherwise considered by EPA in the development of this

rulemaking. The principal purposes of the docket are: (1) To allow

interested parties to identify and locate documents so that they can

effectively participate in the rulemaking process and (2) to serve as

the record in case of judicial review (except for interagency review

materials) (Section 307(d)(7)(A)).

B. Paperwork Reduction Act

The information collection requirements of these provisions in this

rule have been submitted for approval to the OMB under the Paperwork

Reduction Act, 44 U.S.C. 3501 et seq. An Information Collection Request

document has been prepared by the EPA (ICR No. 1414.02), and a copy may

be obtained from Sandy Farmer, Information Policy Branch, EPA, 401 M

Street, SW., (2136), Washington, DC 20460, or by calling (202) 260-

2740. These requirements are not effective until OMB approves them and

a technical amendment to that effect is published in the Federal

Register.

The reporting and recordkeeping burden of the information

collection requirements of the provisions for medium sized storage

vessels are included in the estimate of the overall reporting burden,

which is presented in ICR No. 1414.02. The information collection

requirements for the entire rule has an estimated annual reporting

burden averaging 1,400 hours per response, and an estimated annual

recordkeeping burden averaging 5,400 hours per respondent. These

estimates include time for reviewing instructions, searching existing

data sources, gathering and maintaining the data needed, and completing

and reviewing the collection of information.

Send comments regarding the burden estimate or any other aspect of

this collection of information, including suggestions for reducing this

burden, to Chief, Information Policy Branch, EPA, 401 M Street, SW.,

(Mail code 2136); Washington, DC 20460; and to the Office of

Information and Regulatory Affairs, Office of Management and Budget,

Washington, DC 20503, marked ``Attention: Desk Officer for EPA.''

C. Executive Order 12866

This final action regarding provisions applicable to medium sized

storage vessels in facilities subject to the HON has been reviewed in

accordance with Executive Order 12866. Under the terms of the Order,

the Administrator has assessed the potential costs and benefits of the

regulatory action. The methods for and results of these cost and

benefit analyses are described in the HON's Regulatory Impact Analysis

(RIA). The RIA was included in the HON docket at proposal, and thus it

was made available for public comment.

Executive Order 12866 also requires that the record for

``significant'' rules include an assessment of the potentially

effective and reasonably feasible alternatives to the planned action.

The potentially effective and reasonably feasible alternatives to the

control requirements in the HON were also analyzed as part of the rule

development process. The methods for and results of these analyses are

described in the HON's Background Information Document (BID). The BID

was included in the HON docket at proposal, and thus it was also

available for public comment. In addition, many of the alternative

requirements considered by the Administrator were described in the

preamble for the HON proposal.

The potential costs associated with selection of the final

provisions are primarily the result of statutory requirements. All

elements of the cost that are not directly attributable to statutory

requirements were deemed appropriate because the Administrator

determined that they were necessary for administering this program

effectively and efficiently. In assessing the potential costs and

benefits--both quantitative and qualitative--of this rule, the

Administrator has determined that the benefits justify the costs.

The Administrator has also determined that this regulatory action

does not unduly interfere with State, local and tribal governments in

the exercise of their governmental functions.

D. Regulatory Flexibility Act Compliance

The Regulatory Flexibility Act (5 U.S.C. 601 et seq.) requires the

EPA to consider potential impacts of Federal regulations on small

business entities. If a preliminary analysis indicates that a proposed

regulation would have a significant economic impact on 20 percent or

more of small entities, then a regulatory flexibility analysis must be

prepared.

Regulatory impacts are considered significant if any of the

following criteria are met: (1) Compliance increases annual production

costs by more than 5 percent, assuming costs are passed on to

consumers; (2) compliance costs as a percentage of sales for small

entities are at least 10 percent more than compliance costs as a

percentage of sales for large entities; (3) capital costs of compliance

represent a ``significant'' portion of capital available to small

entities, considering internal cash flow plus external financial

capabilities; or (4) regulatory requirements are likely to result in

closures of small entities.

The potential costs of the requirements for medium sized storage

vessels were considered as part of the economic impact analysis for the

entire regulation. The assessment of the economic impacts of the

overall regulation were presented in the April 22, 1994 Federal

Register (59 FR 19449). Therefore, the addition of the final provisions

to the standard does not alter the conclusion that the standard is not

expected to have a significant economic impact on a substantial number

of small firms.

Pursuant to the provisions of 5 U.S.C. 605(b), I hereby certify

that this attached rule will not have an economic impact on small

entities because no additional costs will be incurred.

List of Subjects in 40 CFR Part 63

Environmental protection, Air pollution control, Hazardous

substances, Reporting and recordkeeping requirements.

Dated: May 27, 1994.

Carol M. Browner,

Administrator.

For the reasons set out in the preamble, part 63, title 40, chapter

I, of the Code of Federal Regulations is amended as follows:

PART 63--[AMENDED]

1. The authority citation for part 63 continues to read as follows:

Authority: Sections 101, 112, 114, 116, and 301 of the Clean Air

Act (42 U.S.C. 7401, et seq., as amended by Pub. L. 101-549, 104

Stat. 2399).

Subpart G--National Emission Standards for Organic Hazardous Air

Pollutants from Synthetic Organic Chemical Manufacturing Industry

Process Vents, Storage Vessels, Transfer Operations, and Wastewater

2. Table 5 of the appendix to subpart G is revised to read as

follows:

Table 5.--Group 1 Storage Vessels at Existing Sources

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

Vapor

Vessel capacity (cubic meters) Pressure\1\

(kilopascals)

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

75 capacity 13

.1

151 capacity................................. 5.

2

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

\1\Maximum true vapor pressure of total organic HAP at storage

temperature.

[FR Doc. 94-13666 Filed 6-3-94; 8:45 am]

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