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."
                               Vol. 59,No. 046
                                 59 FR 11018
                            Wednesday, March 09, 1994

  AGENCY:  ENVIRONMENTAL PROTECTION AGENCY (EPA)
  DOC TYPE:  Proposed Rules
  CFR:  40 CFR Part 63
  NUMBER:  AD-FRL-4846-1
  DATES:  DATES: Comments must be received on or before April 8, 1994.
  CONTACT:  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.
  ADDRESS:  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.
  ACTION:  ACTION: Reopening of public comment period.
  SUMMARY:  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.
  WORD COUNT:  1,465
  TEXT: 
   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 {pg 11019} 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.
  INTERNAL DATA:  FR Doc. 94-5419; Filed 3-8-94; 8:45 am; BILLING CODE 6560-50-P