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