National Emission Standards for Hazardous Air Pollutants for Source Categories: Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry and Other Processes Subject to the Negotiated Regulation for Equipment Leaks; Pulp and Paper Production; and Chromium Emissions From Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks: Determination of MACT ``Floor.''

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[AD-FRL-4846-1]

National Emission Standards for Hazardous Air Pollutants for

Source Categories: Organic Hazardous Air Pollutants From the Synthetic

Organic Chemical Manufacturing Industry and Other Processes Subject to

the Negotiated Regulation for Equipment Leaks; Pulp and Paper

Production; and Chromium Emissions From Hard and Decorative Chromium

Electroplating and Chromium Anodizing Tanks: Determination of MACT

``Floor.''

AGENCY: Environmental Protection Agency (EPA).

ACTION: Reopening of public comment period.

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SUMMARY: On December 31, 1992 (57 FR 62608), 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). The initial public comment period closed on April 19, 1993, but

EPA subsequently reopened the comment period for 30 days on October 15,

1993 (58 FR 53478) to take additional comment on certain issues. In the

final action regarding the December 31, 1992 proposal, which was signed

on February 28, 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. With this notice, EPA reopens 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. The maximum achievable

control technology (MACT) ``floor'' decision that EPA will make in this

rulemaking will have broad precedential effect, and will presumptively

be followed in subsequent MACT rulemakings, including the pulp and

paper and chromium electroplating rulemakings. EPA plans to take final

action regarding the provisions applicable to medium storage vessels

within 90 days of publication of this notice.

DATES: Comments must be received on or before April 8, 1994.

ADDRESSES: Comments. Comments should be submitted (in duplicate if

possible) to the EPA's Air and Radiation Docket and Information Center

(6102), ATTN: Docket Number A-90-19, room M1500, U.S. Environmental

Protection Agency, 401 M Street, SW, Washington, DC 20460.

Dockets. The following dockets contain supporting information used

in developing the proposed provisions. Docket Number A-90-19 contains

information specific to emissions averaging and 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, 410 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) 541-5299. 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: On December 31, 1992 (57 FR 62608), EPA

proposed certain standards to regulate the emissions of certain organic

hazardous air pollutants from synthetic organic chemical manufacturing

industry (SOCMI) production processes and seven other processes that

are part of major sources under section 112 of the Clean Air Act as

amended in 1990 (the Act). The proposed rule is commonly referred to as

the hazardous organic NESHAP or HON. In a separate notice, EPA is

taking final action on virtually all aspects of that proposal but is

deferring final action regarding the portion of the emission standards

for emissions from one of the types of emission points covered by the

proposal, medium storage vessels. The reason EPA is deferring final

action regarding regulation of medium storage vessels is to reopen the

comment period to take comments regarding the nature of the ``floor''

under section 112(d)(3)(A) and the appropriate level of control for

medium storage vessels. Consequently, for purposes of this rulemaking,

the Agency will consider only comments limited to the interpretation of

the language in section 112(d)(3)(A) regarding the establishment of the

``floor'' and 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.

In other proposals regarding MACT standards, EPA has noted the

possibility of two interpretations of the language in section

112(d)(3)(A) and (B) requiring that EPA set standards no less stringent

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

12 percent of the existing sources'' if there are at least 30 sources

in a category or ``the average emission limitation achieved by the best

performing 5 sources'' if there are fewer than 30 sources in a

category. (See 58 FR 66078 (December 17, 1993) (pulp and paper); 58 FR

65768, 65770 (December 16, 1993) (chromium electroplating).) In

essence, the difference between the two interpretations is that one

would result in the floor being established at the level of control

that represents the average (the mean, median, or other appropriate

statistical measure of central tendency) level of control achieved by

the best performing 12 percent of existing sources, which would be

generally equivalent to the 94th percentile of sources, while the other

would result in the floor being the average level of control achieved

by the source at the 88th percentile if all sources were ranked from

the most controlled (100th percentile) to the least controlled (1st

percentile).

The first interpretation is based on grouping the words ``average

emission limitation achieved by'' together in a single phrase and asks

what is the ``average emission limitation achieved by'' the best

performing 12 percent (or best performing 5 sources in the case of

section 112(d)(3)(B)). This interpretation places the emphasis on

``average.'' It would correspond to first identifying the best

performing 12 percent of the existing sources, then determining the

average emission limitation achieved by these sources as a group (i.e.,

generally the level of control achieved by the 94th percentile).

The second interpretation groups the words ``average emission

limitation'' into a single phrase and asks what ``average emission

limitation'' is ``achieved by'' all members of the best performing 12

percent. In this case, the ``average emission limitation'' might be

interpreted as the average reduction across HAPs emitted by an emission

point over time. Under this interpretation, EPA would look at the

average emission limits achieved by each of the best performing 12

percent of existing sources, and take the average limit that is

``achieved'' by all sources within the group (i.e., the average level

of control achieved by the 88th percentile source or the level of

control achieved by the fifth source among the top five in the case of

section 112(d)(3)(B)).

The two possible interpretations are also described in detail in

the proposals regarding the pulp and paper MACT standard (see 58 FR

66136-137 (December 17, 1993), and the chromium electroplating MACT

standard (see 58 FR 65768, 65770 (December 16, 1993).

As described in section V.C.1. of the preamble to the final HON

rule signed February 28, 1994, EPA has reevaluated and revised the

medium storage vessel data base since the December 31, 1992 proposal.

EPA's revised data base indicates that, for medium storage vessels, 6

percent of the vessels are controlled with either a 90-percent

efficient control device or an internal floating roof (IFR) or external

floating roof (EFR) with a continuous seal. All of the controlled

medium-sized vessels contained liquids with vapor pressures of 13.1 kPa

(1.9 psia). The arithmetical average, or mean, characteristics of the

top 12 percent of the medium vessels would not represent the

performance of any known technology. However, if the median were used

to represent the average, the floor would require control of vessels

storing liquids with vapor pressures of 13.1 kPa (1.9 psia) or greater

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

continuous seal. This is the same vapor pressure that was identified in

the December 31, 1992 proposal. With the revised data base, however, if

the floor is established at the average level of control achieved by

the 88th percentile source, the floor would require no control. (At the

time of the December 31, 1992 proposal, EPA had determined that about

30 percent of medium storage vessels storing liquids with vapor

pressures of 13.1 kPa (1.9 psia) or higher were controlled with the

reference technology. Thus, at that time, either of the two

interpretations of the statutory language regarding the establishment

of the floor would have resulted in the floor being established at the

level at which the control requirements were proposed.)

EPA solicits comment on the proper interpretation of the statutory

language regarding the establishment of the floor. EPA also solicits

comment on whether the portion of the emission standard concerning

medium storage vessels proposed in the December 31, 1992 HON proposal

is appropriate if those proposed controls were to be determined to be

more stringent than the floor, rather than to be at the floor as EPA

believed at the time of that proposal. EPA intends to take final action

regarding the provisions applicable to medium storage vessels within 90

days of the publication of this notice.

The MACT ``floor'' decision that EPA will make in this rulemaking

will have broad precedential effect, and will presumptively be followed

in subsequent MACT rulemakings, including the pulp and paper and

chromium electroplating rulemakings. Consequently, commenters on the

pulp and paper and chromium electroplating proposals should submit any

comments they may have on the legal issue to the HON docket. EPA will

consider comments on this issue already submitted in those rulemakings

if they are resubmitted to the HON docket, but will not consider them

in this proceeding for any purpose other than addressing the legal

issue regarding the interpretation of the floor provisions of section

112(d)(3).

Dated: February 28, 1994.

Carol M. Browner,

The Administrator.

[FR Doc. 94-5419 Filed 3-8-94; 8:45 am]

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