National Emission Standards for Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing, 40316-40342 [06-5970]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 71, Number 135 (Friday, July 14, 2006)]
[Rules and Regulations]
[Pages 40316-40342]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-5970]



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Part V





Environmental Protection Agency





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40 CFR Part 63



National Emission Standards for Hazardous Air Pollutants: Miscellaneous 
Organic Chemical Manufacturing; Final Rule

Federal Register / Vol. 71, No. 135 / Friday, July 14, 2006 / Rules 
and Regulations

[[Page 40316]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2003-0121; FRL-8190-5]
RIN 2060-AM43


National Emission Standards for Hazardous Air Pollutants: 
Miscellaneous Organic Chemical Manufacturing

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule; amendments.

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SUMMARY: On November 10, 2003, EPA promulgated national emission 
standards for hazardous air pollutants for miscellaneous organic 
chemical manufacturing. Several petitions for judicial review of the 
final rule were filed in the United States Court of Appeals for the 
District of Columbia Circuit. Petitioners expressed concern with 
various requirements in the final rule, including applicability of 
specific operations and processes, the leak detection and repair 
requirements for connectors, criteria to define affected wastewater 
streams requiring control, control requirements for wastewater streams 
that contain only soluble hazardous air pollutants, the definition of 
``process condensers,'' and recordkeeping requirements for Group 2 
batch process vents. In this action, EPA amends the final rule to 
address these issues and to correct inconsistencies that have been 
discovered during the review process.

DATES: Effective Date: July 14, 2006.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OAR-2003-0121. All documents in the docket are listed on the 
www.regulations.gov Web site. Although listed in the index, some 
information is not publicly available, e.g., confidential business 
information or other information whose disclosure is restricted by 
statute. Certain other material, such as copyrighted material, is not 
placed on the Internet and will be publicly available only in hard copy 
form. Publicly available docket materials are available either 
electronically through www.regulations.gov or in hard copy at the Air 
and Radiation Docket, Docket ID No. EPA-HQ-OAR-2003-0121, EPA/DC, EPA 
West, Room B-102, 1301 Constitution Ave., NW., Washington, DC. The 
Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The telephone number for the Public 
Reading Room is (202) 566-1744, and the telephone number for the Air 
and Radiation Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Randy McDonald, Office of Air 
Quality Planning and Standards, Sector Policies and Programs Division, 
Coatings and Chemicals Group (E143-01), U.S. EPA, Research Triangle 
Park, NC 27711, telephone number: (919) 541-5402, fax number: (919) 
541-0246; e-mail address: mcdonald.randy@epa.gov.

SUPPLEMENTARY INFORMATION: 
    Regulated Entities. Categories and entities potentially regulated 
by this action include:

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                                                         Examples of
          Category               NAICS code \1\      regulated entities
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Industry...................  3251, 3252, 3253,      Producers of
                              3254, 3255, 3256,      specialty organic
                              and 3259, with         chemicals,
                              several exceptions.    explosives, certain
                                                     polymers and
                                                     resins, and certain
                                                     pesticide
                                                     intermediates.
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\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. To determine whether your facility is regulated by this action, 
you should examine the applicability criteria in 40 CFR 63.2435 of 
subpart FFFF (national emission standards for hazardous air pollutants 
(NESHAP) for miscellaneous organic chemical manufacturing). If you have 
any questions regarding the applicability of this action to a 
particular entity, consult either the air permit authority for the 
entity or your EPA regional representative as listed in 40 CFR 63.13 of 
subpart A (General Provisions).
    World Wide Web (WWW). In addition to being available in the docket, 
an electronic copy of the final action will also available on the WWW 
through the Technology Transfer Network (TTN). Following signature, a 
copy of the final action will be posted on the TTN's policy and 
guidance page for newly proposed or promulgated rules at https://
www.epa.gov/ttn/oarpg/. The TTN provides information and technology 
exchange in various areas of air pollution control.
    Judicial Review. Under section 307(b)(1) of the Clean Air Act 
(CAA), judicial review of the final amendments is available only by 
filing a petition for review in the United States Court of Appeals for 
the District of Columbia Circuit by September 12, 2006. Under section 
307(d)(7)(B) of the CAA, only an objection to the final amendments that 
was raised with reasonable specificity during the period for public 
comment may be raised during judicial review. Moreover, under section 
307(b)(2) of the CAA, the requirements established by the final 
amendments may not be challenged separately in any civil or criminal 
proceedings brought by EPA to enforce these requirements.
    Section 307(d)(7)(B) of the CAA further provides that ``[o]nly an 
objection to a rule or procedure which was raised with reasonable 
specificity during the period for public comment (including any public 
hearing) may be raised during judicial review.'' This section also 
provides a mechanism for us to convene a proceeding for 
reconsideration, ``[i]f the person raising an objection can demonstrate 
to the EPA that it was impracticable to raise such objection within 
[the period for public comment] or if the grounds for such objection 
arose after the period for public comment (but within the time 
specified for judicial review) and if such objection is of central 
relevance to the outcome of the rule.'' Any person seeking to make such 
a demonstration to us should submit a Petition for Reconsideration to 
the Office of the Administrator, U.S. EPA, Room 3000, Ariel Rios 
Building, 1200 Pennsylvania Ave., NW., Washington, DC 20460, with a 
copy to both the person(s) listed in the preceding FOR FURTHER 
INFORMATION CONTACT section, and the Associate General Counsel for the 
Air and Radiation Law Office, Office of General Counsel (Mail Code 
2344A), U.S. EPA, 1200 Pennsylvania Ave., NW., Washington, DC 20004.
    Organization of This Document. The information presented in this 
preamble is organized as follows:

I. Background
II. Summary of the Final Amendments
    A. Applicability
    B. Emission Limits, Compliance Options, and Initial Compliance 
Requirements
    C. Monitoring Requirements
    D. Recordkeeping and Reporting
III. Response to Comments
    A. Applicability

[[Page 40317]]

    B. Requirements for Process Vents
    C. Requirements for Wastewater
    D. Requirements for Equipment Leaks
    E. Initial Compliance Requirements
    F. Monitoring Requirements
    G. Recordkeeping and Reporting Requirements
    H. Overlap With Other Rules
    I. Definitions
    J. Miscellaneous Technical Corrections
IV. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions That Significantly Affect 
Energy Supply, Distribution, or Use
    I. National Technology Transfer Advancement Act
    J. Congressional Review Act

I. Background

    On November 10, 2003, we promulgated NESHAP for miscellaneous 
organic chemical (MON) manufacturing as subpart FFFF of 40 CFR part 63. 
Petitions for review of the MON were filed in the United States Court 
of Appeals for the District of Columbia Circuit by American Chemistry 
Council, Eastman Chemical Company, Clariant LSM (America), Inc., Rohm 
and Haas Company, General Electric Company, Coke Oven Environmental 
Task Force, and Lyondell Chemical Company (collectively 
``Petitioners'').\1\ These matters were consolidated into American 
Chemical Council, et al. v. EPA, No. 04-1004, 04-1005, 04-1008, 04-
1009, 04-1010, 04-1012, 04-1013 (District of Columbia Circuit). Issues 
raised by the petitioners included applicability of the final rule; 
leak detection and repair requirements for connectors; definitions of 
process condenser, continuous process vent, and Group 1 wastewater; 
treatment requirements for wastewater that is Group 1 only for soluble 
hazardous air pollutants (SHAP); recordkeeping for Group 2 batch 
process vents; and notification requirements for Group 2 emission 
points that become Group 1 emission points. In early October 2005, the 
parties signed a settlement agreement. Pursuant to section 113(g) of 
the CAA, notice of the settlement was published in the Federal Register 
on October 26, 2005 (70 FR 61814).
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    \1\ The Fertilizer Institute and Arteva Specialties S. `ar.l 
also filed petitions for review but voluntarily withdrew their 
petitions.
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    On December 8, 2005, we proposed amendments to subpart FFFF to 
address the issues raised by Petitioners and made other corrections and 
clarifications to ensure that the final rule is implemented as 
intended. We received a total of 20 comment letters from 18 
stakeholders. Most of the letters were from companies that will have 
affected sources under subpart FFFF, three were from industry trade 
associations, three were from environmental consulting firms, and one 
was from a law firm on behalf of some of the petitioners. The final 
amendments reflect full consideration of the petition, and all of the 
public comments we received on the proposed amendments.

II. Summary of the Final Amendments

    The final amendments clarify applicability of subpart FFFF, provide 
additional compliance options, modify initial and continuous compliance 
requirements, and simplify recordkeeping and reporting requirements. 
Significant changes are summarized in the sections below. Additional 
clarifications and corrections are highlighted in Table 1 to this 
preamble and in the preamble to the proposed amendments (70 FR 73098, 
December 8, 2005). Collectively, these provisions will reduce the 
burden associated with demonstrating compliance without affecting 
emissions control or the ability of enforcement agencies to ensure 
compliance.

A. Applicability

    The final amendments exempt carbon monoxide production and 
additional polymer finishing operations from subpart FFFF. In the 
definition of the term ``miscellaneous organic chemical manufacturing 
process,'' the final amendments clarify the end point of processes that 
produce solid products.

B. Emission Limits, Compliance Options, and Initial Compliance 
Requirements

    Many of the changes in the final amendments involve requirements 
for process vents. For example, Table 2 in the amended rule allows 
floating roof technology to control batch process vent emissions from 
process tanks. The final amendments also change the definition of the 
term ``continuous process vent'' to include all continuous operations, 
not just reactors, air oxidation reactors, and distillation units. A 
corresponding change has been made in the definition of the term 
``surge control vessel.'' Another change to the definition of the term 
``continuous process vent'' requires determinations of continuous 
process vents prior to combination with emissions from another 
miscellaneous organic chemical manufacturing process unit (MCPU).
    Table 3 in the final rule currently requires control of 
``particulate matter (PM) hazardous air pollutant (HAP)'' emissions 
from process vents at new sources. The amendments replace requirements 
for ``PM HAP'' with requirements for ``HAP metals.'' One of the related 
changes is that the emissions threshold above which control is required 
has been changed from 400 pounds per year (lb/yr) of PM HAP to 150 lb/
yr of HAP metals. Another change in the amended rule is that Method 29 
of appendix A of 40 CFR part 60 is allowed as an alternative to Method 
5 of appendix A of 40 CFR part 60.
    We have amended the definition of the term ``process condenser'' to 
clarify what it means for a condenser to be ``integral to the MCPU.'' 
Under the current definition, condensers that receive vapor streams 
from batch operations in an MCPU at temperatures below the boiling or 
bubble point of the HAP are not process condensers. The amended 
definition includes most of these condensers, provided they are capable 
of and normally used for the purpose of recovering chemicals for fuel 
value, use, or reuse, or for sale for fuel value, use, or reuse. 
Exceptions are provided for condensers that are considered to be part 
of recovery devices.
    The final amendments specify corrected procedures for using 
specified equations to calculate uncontrolled emissions from process 
condensers. The revised procedures require consideration of the 
condenser exit gas temperature and composition of the condensate. 
Alternatively, uncontrolled emissions from process condensers may be 
estimated based on engineering assessments under the same conditions as 
the final rule currently allows for estimating emissions directly from 
the process vessels. The final amendments also specify initial 
compliance requirements for process condensers. You must either measure 
the exhaust gas temperature and show it is less than the boiling or 
bubble point of the substance in the process vessel or perform a 
material balance around the vessel and condenser to show that at least 
99 percent of the material vaporized while boiling is condensed.
    The final amendments specify that biofilters are an option for 
complying with the 95 percent reduction emission limit for batch 
process vents (see Table

[[Page 40318]]

2 to subpart FFFF of part 63). Related amendments in 40 CFR 
63.2460(c)(9) specify initial and continuous compliance requirements 
for biofilters. A performance test must be conducted to demonstrate 
initial compliance. Either temperature or organic monitoring devices 
are required to demonstrate continuous compliance. Average temperatures 
must be determined if you elect to measure temperature at several 
locations in the biofilter bed. As for other types of control devices, 
the amendments related to biofilters also cross-reference the testing 
and continuous parameter monitoring system(s) (CPMS) requirements in 40 
CFR part 63, subpart SS.
    The final amendments add a compliance option in Table 3 of subpart 
FFFF of 40 CFR part 63 for hydrogen halide and halogen HAP emissions 
from process vents. A halogen atom mass flow rate emission limit of 
0.45 kilograms per hour (kg/hr) is allowed as an alternative to the 
current emission limits that require either a 99 percent reduction or 
control to an outlet concentration limit of 20 parts per million by 
volume (ppmv). This mass emission limit applies to each individual 
continuous process vent and to the collection of all batch process 
vents within an MCPU.
    The final amendments change several of the requirements for 
wastewater. The concentrations and mass discharge rates of partially 
soluble HAP (PSHAP), SHAP, and total HAP that define a Group 1 
wastewater stream have been changed. The definition of the term ``point 
of determination'' (POD) has been changed to specify that the point 
where effluent is discharged from a scrubber or other control device is 
a POD. Methyl ethyl ketone has been removed from the list of PSHAP in 
Table 8 to subpart FFFF of part 63.\2\ A new 40 CFR 63.2485(o) requires 
the CPMS records specified in 40 CFR 63.998(c)(1) in addition to the 
records specified in 40 CFR 63.147(d) for non-flare control devices. 
Finally, a new compliance option is included in 40 CFR 63.2485(n) that 
allows certain waste management units in a biotreatment system to be 
uncovered if the wastewater being treated is Group 1 only for SHAP. 
This option also allows lift stations with a volume larger than 10,000 
gallons to have openings sized as necessary for proper venting as an 
alternative to the currently specified vent pipe dimensions in 40 CFR 
63.136(e)(2)(ii)(A). Amendments in 40 CFR 63.2485(n) also added initial 
compliance procedures that are specific to the new compliance option.
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    \2\ MEK has been removed as a result of its removal from the CAA 
section 112(b)(1) list of HAP. [70 FR 75047, December 19, 2005]
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    For equipment leaks, the final amendments allow compliance with 40 
CFR part 63, subpart H as an alternative to compliance with either 40 
CFR part 63, subpart UU or 40 CFR part 65, subpart F. The amendments 
eliminate the option for existing sources of complying with 40 CFR part 
63, subpart TT. However, the final amendments also allow two exceptions 
to the three available options. First, for pumps at an existing 
affected source, you may elect to comply with a leak definition of 
10,000 parts per million (ppm) as an alternative to the leak 
definitions specified in the cross-referenced rules. Second, for 
connectors in gas service or light liquid service at any affected 
source, you may elect to comply with the requirements for connectors in 
heavy liquid service. The final amendments also specify that bench-
scale processes are exempt from the equipment leak requirements.
    The final amendments eliminate reporting requirements for offsite 
cleaning and reloading facilities that control emissions from rail cars 
and tank trucks that are used in vapor balancing for storage tanks at 
the affected source. For an offsite cleaning or reloading facility that 
is subject to any other NESHAP under 40 CFR part 63, the final 
amendments specify that compliance with the monitoring, recordkeeping, 
and reporting requirements in the other rule demonstrates compliance 
with the requirements in subpart FFFF of 40 CFR part 63.
    Final amendments to 40 CFR 63.2445 clarify that an initial 
compliance demonstration must be conducted within 150 days after any of 
the following process changes: A Group 2 emission point becomes a Group 
1 emission point, hydrogen halide and halogen HAP emissions from the 
sum of all process vents in a process increase to more than 1,000 lb/
yr, or a small control device for process vent or transfer rack 
emissions becomes a large control device.

C. Monitoring Requirements

    The final amendments include several changes to the parameter 
monitoring requirements specified in 40 CFR 63.2450(k). For halogen 
scrubbers, monitoring caustic strength of the effluent is allowed as an 
alternative to measuring pH. If the halogen scrubber controls emissions 
only from batch process vents, the caustic strength or pH may be 
measured daily instead of continuously. For absorbers that control 
organic compounds and use water as the scrubbing fluid, liquid and gas 
flow rates may be monitored instead of the parameters in the current 
rule. The periodic verification option for control devices that control 
less than 1 ton per year of HAP is now allowed for all control devices, 
not just those that control only batch process vents.

D. Recordkeeping and Reporting

    The final amendments reduce or eliminate recordkeeping requirements 
in 40 CFR 63.2525(e) for Group 2 batch process vents. Recordkeeping is 
eliminated for Group 2 batch process vents that are always controlled 
with either a flare that meets the requirements of 40 CFR 63.987 or any 
other control device that meets the requirements for Group 1 batch 
process vents, provided the worst-case conditions for the control 
device includes the contribution of all Group 2 batch process vents. 
Reduced recordkeeping is allowed if non-reactive organic HAP is the 
only HAP in the process and usage is less than 10,000 lb/yr or if 
emissions are less than 1,000 lb/yr. Estimating uncontrolled organic 
HAP emissions is not required if you demonstrate that non-reactive 
organic HAP usage is less than 10,000 lb/yr. Data and supporting 
rationale explaining why non-reactive organic HAP usage will be less 
than 10,000 lb/yr must be included in your notification of compliance 
status report.
    The final amendments also reduce or clarify reporting requirements. 
As clarification for process changes in 40 CFR 63.2520(e)(10), it 
should be noted that a new MCPU is created when a new product is made 
which is not part of an existing family of materials. Process changes 
to an existing MCPU such as the addition of new or different equipment, 
use of different feedstock, or addition of a parallel process may be a 
change in the operating scenario, but do not constitute a new MCPU. The 
definition of the term ``batch process vent'' has been amended to 
eliminate reporting requirements associated with determinations that 
emissions from batch operations have HAP emissions below the thresholds 
for batch process vents. The final amendments eliminate the requirement 
in 40 CFR 63.2520(e)(10)(ii)(C) of the final rule to provide a 60-day 
advance notification before batch process vents change from Group 2 to 
Group 1. Under the amended rule, you must document such a change in 
status in your notification of compliance status report in accordance 
with 40 CFR 63.2520(e)(10)(i). We changed 40 CFR 63.2465(b) to specify

[[Page 40319]]

that the results of engineering assessments used to estimate 
uncontrolled hydrogen halide and halogen HAP emissions are to be 
documented in your notification of compliance status report, not your 
precompliance report. Finally, the amended rule requires operating logs 
(and copies of the applicable logs in compliance reports) only for 
processes with batch process vents from batch operations, not all 
processes.

III. Response to Comments

A. Applicability

    Comment: Although not directly related to the proposed amendments, 
one commenter expressed concern that, despite previous attempts at 
clarification, a potential for overlap and conflict between the 
applicability provisions in the Miscellaneous Organic Chemical 
Manufacturing NESHAP (40 CFR part 63, subpart FFFF) and the 
miscellaneous coating manufacturing NESHAP (40 CFR part 63, subpart 
HHHHH) still exists. Based on the rules as currently written and 
additional guidance from EPA (70 FR 25678, May 11, 2005), the commenter 
understands that any process that produces a material that is used as a 
coating is subject to 40 CFR part 63, subpart HHHHH. The commenter has 
two concerns with this requirement. First, it is not clear which rule 
applies to the production of materials that have both coating and non-
coating uses. Second, some coating manufacturing processes involve 
traditional chemical manufacturing operations, including reactions, 
which differ significantly from the processes consisting of mixing and 
blending operations that were used to develop the maximum achievable 
control technology (MACT) floor and regulatory requirements in 40 CFR 
part 63, subpart HHHHH. On the other hand, these processes are similar 
to processes that were used to develop the MACT floor and regulatory 
requirements in 40 CFR part 63, subpart FFFF.
    To resolve the conflicts, the commenter requested that we issue a 
separate rulemaking to revise definitions in the Miscellaneous Coating 
Manufacturing NESHAP. The commenter, in conjunction with other 
companies, suggested changes to definitions in earlier communications 
with EPA. If changes are made before the compliance dates of both 
rules, needless effort to prepare and review precompliance reports for 
these situations can be avoided.
    Response: We share the commenter's concern about the potential for 
conflict in applicability determinations. To clarify the applicability 
and eliminate the conflict, we have proposed changes to the definition 
of the term ``coating'' in the Miscellaneous Coating Manufacturing 
NESHAP (71 FR 28639, May 17, 2006). One of the proposed changes would 
clarify that only material produced by blending, mixing, dilution, or 
other formulation operations would be a coating. Thus, a process that 
involves only formulation operations would be subject to 40 CFR part 
63, subpart HHHHH if the product is a coating. A second proposed change 
would clarify applicability for processes that involve chemical 
synthesis or separation of formulation components prior to the 
formulation operations. If the synthesized or separated material is 
stored as an isolated intermediate or final product prior to use in the 
formulation operation, the synthesis or separation process is subject 
to 40 CFR part 63, subpart FFFF. Thus, applicability of 40 CFR part 63, 
subpart FFFF would end with the storage vessel fed from the synthesis 
or separation operation, and 40 CFR part 63, subpart HHHHH would apply 
following storage through final production of the coating. When the 
synthesized or separated component is not stored before use in a 
formulation step, the second proposed change to the definition of the 
term ``coating'' would specify that a coating does not include 
materials made in processes where a formulation component is 
synthesized by chemical reaction or separation activity and then 
transferred to another vessel (without storage) where it is formulated 
to produce a material used as a coating. The preamble to these proposed 
amendments to the Miscellaneous Coating Manufacturing NESHAP states 
that comments must be received on or before July 3, 2006.
    Comment: One commenter described how they think several tanks in a 
specific miscellaneous organic chemical manufacturing process would be 
classified under the amended rule. According to the commenter, a molten 
material from batch reactors is collected in tank A. Typically, the 
material from tank A is sent to a continuous centrifuge to remove a 
catalyst. The catalyst-free material is then transferred to either tank 
B or tank C. Still molten, material in tanks B and C is either 
transferred to rail cars for shipment or used onsite as feed material 
for a flaker or pastille maker. The flaker and pastille maker operates 
continuously, except when it is necessary to switch from one feed tank 
to the other. The commenter believes tank A is a surge control vessel, 
and tanks B and C are either storage tanks or surge control vessels.
    Response: Although this is not the proper forum for a site-specific 
applicability determination, we will provide a general assessment based 
on the limited available information. Because it is managing the flow 
of material into a continuous operation, tank A is a surge control 
vessel. Since the material in tanks B and C is sometimes sold, these 
tanks mark the end of the process, and the tanks are storage tanks. In 
this case, the flaker and pastille maker is a separate process.
    The determination would be more difficult if all of the material in 
tanks B and C was used onsite. If material were sometimes added to and 
withdrawn from these tanks simultaneously, then they would be managing 
flow to a continuous operation, and they would be surge control 
vessels. On the other hand, if it could be demonstrated that the tanks 
are being used solely for storage, then the molten material would be an 
isolated intermediate, and tanks B and C would be storage tanks. Note 
that in table 1 to this preamble we describe a change in the final 
amendments to the definition of ``isolated intermediates.'' This change 
clarifies that storage equipment for isolated intermediates is part of 
the MCPU that produces the isolated intermediate.
    Comment: One commenter thinks polymer products should not be 
regulated as ``volatile organic liquids'' under either subpart FFFF or 
other regulatory programs because they have very high molecular weights 
and negligible vapor pressure.
    Response: Processes that produce certain polymer products are 
regulated under 40 CFR part 63, subpart FFFF if HAP are used in the 
process. However, only the HAP are subject to emission limits. The non-
HAP polymer products themselves are not subject to emission limits 
under 40 CFR part 63, subpart FFFF. The requirements in other 
regulatory programs are not addressed in this response: Because today's 
action deals only with amendments to 40 CFR part 63, subpart FFFF.

B. Requirements for Process Vents

    Comment: The proposed amendments included an additional compliance 
option for batch process vents that would allow the use of biofilters 
to comply with the 95 percent reduction option. One commenter requested 
that this option be made available for continuous process vents as 
well. The commenter realizes that, technically, biofilters may be used 
to comply with the 98 percent reduction option in table 1 to subpart 
FFFF, but the commenter

[[Page 40320]]

believes this is not feasible with current biofilter technology. To 
support his request, the commenter noted that biofilters have 
environmental benefits relative to the combustion devices they are 
likely to supplant. Specifically, both the consumption of fossil fuels 
and the generation of criteria pollutant emissions would be lower if 
continuous process vents are controlled using biofilters. The commenter 
also noted that there is no technological barrier to using biofilters 
to control emissions from continuous operations, and there is 
regulatory precedent for their use to control emissions from continuous 
operations (i.e., 40 CFR part 63, subpart DDDD and subpart UUUU).
    Response: We have decided not to include the requested biofilter 
option at this time. Although we agree that biofilters have some 
environmental advantages over combustion devices, we are concerned that 
the difference between 98 percent and 95 percent reduction in HAP 
emissions is not offset by the benefits of reduced fuel use and 
criteria pollutant emissions. Analysis of the offsets was not necessary 
for batch process vents because the rule already included a 95 percent 
reduction option before the biofilter option was proposed.
    This issue is not closed. We have initiated a study to investigate 
the applicability of biofilters for continuous process vent emissions 
from miscellaneous organic chemical manufacturing processes. Some of 
the things we would like to determine are as follows. What level of 
control can be achieved? Does the level of control vary for different 
HAP? What effect do other emission stream characteristics such as flow 
rate and temperature have on the control efficiency? How much of the 
HAP removed from the emission stream is transferred to wastewater 
discharges? How much electricity is needed to run fans and pumps 
associated with a biofilter? How much solid waste is generated by 
biofilters, and how must it be disposed? Using the information 
collected, we will also reassess the environmental impacts of 
biofilters versus combustion devices. Depending on the results, we may 
decide to propose some type of biofilter option for continuous process 
vents in 40 CFR part 63, subpart FFFF in the future.
    Comment: One of the proposed amendments added a compliance option 
for process vents that emit hydrogen halide and halogen HAP. This 
option, in entry 1.b. of Table 3 to subpart FFFF of 40 CFR part 63, 
would allow compliance by reducing the ``halogen atom mass emission 
rate to <=0.45 halogen HAP kg/hr by venting through a closed vent 
system to a halogen reduction device.'' Three commenters noted that it 
is unclear which vents need to be controlled when the collective 
hydrogen halide and halogen emissions from all vents in a process are 
at least 1,000 lb/yr. The commenters suggested clarifying that the 
limit applies to each individual process vent. According to two of the 
commenters, if a stream that is controlled to <0.45 kg/hr is in 
compliance, then it seems logical that any uncontrolled stream from the 
process that contains <0.45 kg/hr should also be in compliance.
    Response: Application of the 0.45 kg/hr limit for hydrogen halide 
and halogen HAP differs for batch and continuous process vents. It 
applies to the sum of all batch vents and to each individual continuous 
process vent. This approach is consistent with the way limits are 
applied for organic HAP emissions from batch and continuous process 
vents. The language in Table 3 to subpart FFFF of 40 CFR part 63 has 
been changed to clarify the requirements.
    Comment: One commenter requested clarification of the language in 
40 CFR 63.2450(o), which currently states that ``you may not use a 
flare to control halogenated vent streams or hydrogen halide and 
halogen HAP emissions.'' The commenter is concerned that this language 
appears to prohibit all vent streams with hydrogen halide and halogen 
HAP from flares, even if no control of hydrogen halide and halogen HAP 
is required for the stream. To clarify the paragraph, the commenter 
suggests changing it to read as follows: ``You may not use a flare to 
control halogenated vent streams or as a control device for hydrogen 
halide and halogen HAP emissions to comply with Table 3.''
    Response: We have changed 40 CFR 63.2450(o) as suggested by the 
commenter because the suggested language is consistent with our intent, 
and it may eliminate confusion. If hydrogen halide and halogen HAP in a 
vent stream must be controlled to meet the emission limits in Table 3 
to subpart FFFF of 40 CFR part 63, then that vent stream may not be 
vented to a flare. All other vent streams that contain hydrogen halide 
and halogen HAP may be vented to a flare. For example, a continuous 
process vent stream containing less than 0.45 kg/hr of hydrogen halide 
and halogen HAP could be sent to the flare.
    Comment: Two commenters noted that the language in entry 1.a of 
Table 3 to subpart FFFF of 40 CFR part 63 appears to require the use of 
a single closed-vent system to convey hydrogen halide and halogen HAP 
from all process vents in a process to a control device(s). According 
to the commenters, this could be a problem because it is possible that 
the process vents within a process that must be controlled may be 
separated by distances that would make collection into a single closed-
vent system impractical or uneconomical. The commenters suggested 
changing the language to allow for the use of a ``combination of 
closed-vent systems.''
    Response: We did not intend to force the use of a single control 
device (or series of control devices) for all process vents within the 
process. Therefore, we have changed entries 1.a and 1.b in Table 3 to 
subpart FFFF of 40 CFR part 63 to allow venting through ``one or more 
closed-vent systems.'' We also amended entries 1.a, 1.b, and 1.c in 
Table 2 to subpart FFFF of 40 CFR part 63 in the same manner. These 
changes provide flexibility to use as many separate control devices as 
necessary.
    Comment: One commenter requested clarification of the language in 
40 CFR 63.2495(b)(1), which currently specifies that ``Hydrogen halides 
that are generated as a result of combustion control must be controlled 
according to the requirements of 40 CFR 63.994 and the requirements 
referenced therein.'' The commenter is concerned that this language 
appears to require the use of halogen reduction devices regardless of 
the halogen atom concentration in the emission stream that is 
combusted. This conflicts with provisions elsewhere in the rule that 
require the use of halogen reduction devices only when halogenated vent 
streams are combusted.
    Response: To eliminate the inconsistency that the commenter 
identified, we have amended 40 CFR 63.2495(b)(1) to require control of 
hydrogen halides generated by combustion control only ``if any vent 
stream routed to a combustion control is a halogenated vent stream.''
    Comment: One commenter stated that regenerative thermal oxidizers 
(RTO) should be recognized as a form of incineration that can be used 
for control as long as any combined control system meets the 98 percent 
control efficiency or outlet concentration limit.
    Response: RTO are acceptable control devices under the rule. 
Nothing in the rule prohibits their use alone or in combination with 
other devices to meet specified emission limits for organic HAP.

C. Requirements for Wastewater

    Comment: One commenter requested clarification of the POD for 
scrubbers. According to the commenter, the point where effluent is 
discharged from a

[[Page 40321]]

scrubber should be a POD, and the effluent itself should be process 
wastewater, only when the scrubber is used to comply with the emission 
limits for process vents. The commenter suggested adding language like 
that in 40 CFR 63.1256(a)(1)(iii) of the Pharmaceuticals Production 
NESHAP.
    Response: We agree with the commenter that the requirements for 
scrubber effluent need to be clarified. On July 1, 2005, we published 
direct final rule amendments (70 FR 38554) and a parallel proposal (70 
FR 38562) that specified requirements for effluent from control 
devices. We later withdrew these amendments because of adverse comment 
(70 FR 51269, August 30, 2005). As a result, the rule is now silent on 
the requirements for scrubber effluent.
    We disagree with the commenter's assertion that only scrubbers that 
are used to meet emission limits for process vents should have a POD. 
If a process operates a few hours per year, it may have Group 2 batch 
process vent emissions with high HAP concentrations. If such emission 
streams are controlled with a scrubber, we believe that the effluent 
discharges should be considered for possible compliance with wastewater 
requirements.
    After consideration of the comment and evaluation of requirements 
in other rules, we have decided to resolve the existing ambiguity by 
modifying the definition of ``point of determination'' in the final 
amendments. In general, 40 CFR part 63, subpart FFFF references the 
wastewater requirements in the Hazardous Organic NESHAP (HON), 40 CFR 
part 63, subpart G, including the POD definition in 40 CFR 63.111. 
According to this definition, a POD is each point where process 
wastewater exits the chemical manufacturing process unit (CMPU) (or 
MCPU, in the case of 40 CFR part 63, subpart FFFF). However, the term 
does not have the same meaning under 40 CFR part 63, subpart FFFF as it 
does in the HON due to an unintended consequence created by the 
decision to exclude control devices from the MCPU (whereas they are 
part of CMPU under the HON). To make the application of POD under 40 
CFR part 63, subpart FFFF consistent with their application in the HON, 
the final amendments include a freestanding (i.e., non-cross-
referenced) term ``point of determination'' in 40 CFR 63.2550(i) of 40 
CFR part 63, subpart FFFF. This revised definition specifies that a POD 
is each point where process wastewater exits the MCPU or control 
device.
    As a result of this change, effluent discharge points from all 
scrubbers, not just those that are used to meet emission limits for 
process vents, are POD. Discharge points from other types of control 
devices are also POD. The effluent also is process wastewater, as under 
the HON. To determine if the effluent is subject to requirements for 
wastewater, you must determine if it meets any of the Group 1 
wastewater criteria, just like for other process wastewater streams.
    Comment: Several commenters requested that methyl ethyl ketone 
(MEK) be deleted from the list of PSHAP in Table 8 to subpart FFFF of 
40 CFR part 63 because MEK was removed from the list of HAP in the CAA 
on December 19, 2005 (70 FR 75047). One of the commenters suggested a 
separate rulemaking to address the situation before the compliance 
date.
    Response: We agree with the commenters that MEK should no longer be 
listed in Table 8 to subpart FFFF of 40 CFR part 63 because MEK has 
been removed from the HAP list. Therefore, we removed MEK from Table 8 
to subpart FFFF of 40 CFR part 63 in the final rule amendments.

D. Requirements for Equipment Leaks

    Comment: One commenter requested that bench-scale operations be 
exempt from the MON just as in the HON at 40 CFR 63.160(f) and 40 CFR 
63.190(f), the Pharmaceuticals Production NESHAP at 40 CFR 
63.1255(a)(6), and the Pesticide Active Ingredient Production NESHAP at 
40 CFR 63.1363(a)(6). The commenter states that the justification for 
excluding bench-scale operations from the other rules, as stated in the 
preamble to an amendment for the HON (60 FR 18071, April 10, 1995), is 
equally applicable to the MON source category.
    Response: We agree with the commenter and have corrected this 
oversight by adding an exemption for bench-scale batch operations in a 
new 40 CFR 63.2480(d). Although the term ``bench-scale batch 
operations'' is defined in 40 CFR 63.161 of the HON, we also added the 
same definition in the final amendments to 40 CFR 63.2550(i) because 
the term is not defined in 40 CFR part 63, subpart UU or in 40 CFR part 
65, subpart A.
    Comment: One commenter opposed the proposed amendments to the 
requirements for equipment leaks at existing sources in Table 6 to 
subpart FFFF. These changes would eliminate the 40 CFR part 63, subpart 
TT option for MCPU with no continuous process vents in favor of a new 
above-the-floor option that would require all MCPU to comply with 
either 40 CFR part 63, subpart UU, or 40 CFR part 65, subpart F, both 
modified to allow sensory monitoring of connectors in place of Method 
21 monitoring.
    The commenter stated four objections to the proposed changes. 
First, the commenter does not believe we have met the statutory 
requirement to demonstrate that the costs of the new option are 
reasonable, particularly for equipment in an MCPU with no continuous 
process vents. To illustrate this concern, the commenter provided 
information for an example pump and concluded that the additional cost 
to comply with 40 CFR part 63, subpart UU instead of 40 CFR part 63, 
subpart TT could be over $70,000 per ton of HAP removed.
    Second, the commenter disagrees with our assertion that a 
consistent set of options for all MCPU will simplify applicability 
because this determination needs to consider other rules that apply at 
the MON facilities. For example, if a facility with MON batch 
operations is also subject to the Organic Liquid Distribution NESHAP, 
for which 40 CFR part 63, subpart TT is a compliance option, then 
eliminating the 40 CFR part 63, subpart TT option from the MON could 
make applicability more complicated.
    Third, even if the nationwide benefits of reduced connector 
monitoring for continuous operations more than offsets the additional 
nationwide burden to comply with the 40 CFR part 63, subpart UU for all 
MCPU, the commenter is concerned that the offsets are inequitably 
distributed. Facilities primarily engaged in batch chemical 
manufacturing would incur additional costs but receive little or no 
benefit, whereas facilities that primarily operate continuous chemical 
manufacturing processes will receive the benefits but incur little or 
no cost.
    Fourth, the commenter stated that the new leak detection and repair 
(LDAR) options do not appropriately recognize the difference in 
potential environmental impact between batch and continuous operations. 
The commenter noted that, prior to the amendments, 40 CFR part 63, 
subpart FFFF allowed for the fundamental differences of scale and modes 
of operation between continuous and batch operations by properly 
allocating the stringency of equipment leak requirements. The commenter 
argued that the proposed change does neither. The higher stringency of 
40 CFR part 63, subpart UU is appropriate for large continuous 
operations but not for small batch operations.
    Response: In the analysis for the proposed amendments, the MACT 
floor

[[Page 40322]]

for all MCPU was an LDAR program equivalent to the requirements in 40 
CFR part 63, subpart TT, and the above-the-floor option lowered the 
leak definition for pumps and valves to the level specified in 40 CFR 
part 63, subpart UU. Although we stand by our original conclusion that 
the average nationwide impacts of the proposed above-the-floor option 
are reasonable, we also share the commenter's concern that the benefits 
and costs are not distributed equitably among facilities with different 
types of operations, especially when considering the leak detection and 
repair program already implemented at the facility.
    Upon closer examination of the results of the cost analysis, it is 
clear that the incremental impacts for pumps in MCPU that have no 
continuous process vents are much more significant than the impacts for 
valves in those same processes and the impacts for MCPU that have 
continuous process vents. To mitigate the excessive burden for batch 
operations already in compliance with 40 CFR part 63, subpart TT, we 
have modified the above-the-floor option to lower the pump leak 
definition only for MCPU with continuous process vents (the option 
still lowers the leak definition for valves in all MCPU). As a result 
of this change, the incremental impacts for both batch and continuous 
operations are reasonable. For the final amendments, we did not change 
the language in Table 6 to subpart FFFF of 40 CFR part 63 (i.e., the 
LDAR programs in 40 CFR part 63, subpart UU and 40 CFR part 65, subpart 
F are still the starting point for all MCPU). However, new language in 
40 CFR 63.2480(b)(5) and (c)(5) specifies that you may elect to comply 
with a leak definition of 10,000 ppm for pumps in light liquid service 
in an MCPU that has no continuous process vents and is part of an 
existing source.
    In addition to the changes described above for pumps, the final 
amendments also include an additional compliance option for equipment 
leaks. Many facilities with processes that are subject to 40 CFR part 
63, subpart FFFF also have processes that are subject to the equipment 
leak provisions in 40 CFR part 63, subpart H. The requirements in 40 
CFR part 63, subpart H are substantially similar to the requirements in 
40 CFR part 63, subpart UU. Therefore, we decided to modify Table 6 of 
subpart FFFF to 40 CFR part 63 to allow compliance with 40 CFR part 63, 
subpart H as another alternative. This option provides additional 
flexibility, and it may reduce the burden for some owners and operators 
while achieving the same level of emissions control.

E. Initial Compliance Requirements

1. Design Evaluations
    Comment: A proposed amendment to 40 CFR 63.2450(h) would clarify 
that the option to conduct a design evaluation instead of a performance 
test for a small control device applies only to control devices used to 
control process vents and transfer racks because other provisions in 
the rule already allow design evaluations for storage tanks and 
wastewater. Section 63.2450(h) also references the criteria for design 
evaluations in 40 CFR 63.1257(a)(1) of the Pharmaceuticals Production 
NESHAP. One commenter believes it would be preferable to require 
compliance with the design evaluation requirements in 40 CFR 63.985(b) 
for small control devices used to meet the emission limits in Tables 1, 
3, and 5 to subpart FFFF of 40 CFR part 63, and require compliance with 
40 CFR 63.1257(a)(1) only for control devices used to meet the emission 
limits specified in Table 2 to subpart FFFF of 40 CFR part 63. 
According to the commenter, referencing the design evaluation 
procedures in 40 CFR part 63, subpart SS for the emission types subject 
to Tables 1, 3, and 5 to subpart FFFF of 40 CFR part 63 is appropriate 
because the performance test and other requirements in 40 CFR part 63, 
subpart SS also apply to those emission types. The commenter also 
recommended adding the following statement: ``For continuous process 
vents the design evaluation shall be conducted at maximum 
representative operating conditions for the process, unless the 
Administrator specifies or approves alternate operating conditions.''
    Response: Although written in very different styles, the intent of 
the design evaluation requirements in 40 CFR part 63, subpart SS and 
the Pharmaceuticals Production NESHAP are essentially the same, to the 
extent they overlap. We decided not to reference both sets of 
requirements because we believe it is clearer to reference only one 
wherever possible. We selected the criteria in the Pharmaceuticals 
Production NESHAP because they are slightly more comprehensive than the 
procedures in 40 CFR part 63, subpart SS (e.g., they include criteria 
for scrubbers and non-regenerative carbon adsorbers). Furthermore, the 
language in the Pharmaceuticals Production NESHAP is nearly identical 
to the language in 40 CFR 63.139 of the HON, which 40 CFR part 63, 
subpart FFFF references for wastewater control devices.
    We agree with the commenter's suggested clarification regarding the 
conditions under which the design evaluation should be conducted for a 
control device that controls continuous process vents. This language is 
borrowed from 40 CFR 63.997(e)(1)(i), and it will ensure that design 
evaluations are conducted under the same conditions as performance 
tests. It also complements the instructions in 40 CFR 
63.2460(c)(2)(ii), which specify conditions under which a design 
evaluation should be conducted for a control device that controls batch 
process vents. Thus, we added the commenter's suggested language in 40 
CFR 63.2450(h). Along these same lines, we also added a statement 
specifying that a design evaluation for a control device that is used 
to control transfer racks must demonstrate that the required efficiency 
is achieved during the reasonably expected maximum transfer loading 
rate.
2. Requirements After Process Changes
    Comment: Proposed amendments in 40 CFR 63.2445(d), (e), and (f) 
specify requirements that apply after various types of process changes. 
In each case, the proposed amendments specify that a performance test 
or design evaluation is required within 150 days of the process change. 
Two commenters requested clarification of the proposed amendments 
because they noted that an initial compliance demonstration does not 
always require a performance test or design evaluation. For example, 
one commenter pointed out that no performance test should be required 
if the facility complies with the alternative standard or routes the 
emission stream to a fuel gas system. The other commenter described a 
situation where a performance test should not be required because a 
previous test is still valid. According to this commenter, when 
production is scaled up so that Group 2 batch process vents become 
Group 1 batch process vents, production may be shifted to different 
equipment for which initial compliance was previously demonstrated 
under worst-case conditions that are not exceeded by the operating 
scenario for the new process. To clarify the amendments, one commenter 
suggested replacing the references to performance tests and design 
evaluations with a reference to ``an initial compliance demonstration 
as specified in this subpart.''
    Response: Our intent was to require a performance test or design 
evaluation after the specified types of process changes only when a 
performance test or design evaluation would have been required to 
demonstrate initial

[[Page 40323]]

compliance if the situation after the change had existed at the time 
the facility first became subject to 40 CFR part 63, subpart FFFF. The 
commenters correctly observed that in some situations initial 
compliance can be demonstrated without a performance test or design 
evaluation, or it can be demonstrated using a previous performance 
test. Therefore, we revised 40 CFR 63.2445(d), (e), and (f) in the 
final rule amendments to require any applicable initial compliance 
demonstration instead of requiring only a new performance test or 
design evaluation.
3. Calculation of Uncontrolled Emissions
    Comment: One commenter pointed out that the calculation of HAP 
emissions from process condensers requires knowledge of condensate 
receiver composition and condenser exit gas temperature (or direct 
knowledge of exit gas stream composition). In most cases, data on the 
condensate composition is not available. The commenter stated that 
typical errors made in estimating emissions following process 
condensers include use of condenser exit water temperature instead of 
exit gas temperature, lack of an applied material balance, and use of 
reactor vessel liquid phase mole fraction to determine partial pressure 
of condensables in the condenser exit gas (single most common mistake). 
When the operator has no knowledge of the liquid condensate mole 
fractions, a material balance must be used to determine the mole 
fractions present in equilibrium with the exiting emission stream. The 
commenter provided an example of a material balance based on 
noncondensables for a process operation involving toluene and xylene. 
The commenter further points out that for process operations where 
temperature and pressure are changing, the material balance may be 
complex. In summary, the commenter stated that it is essential that the 
noncondensable material balance be applied in conjunction with an 
iterative solution to solve condensate liquid mole fraction for cases 
where liquid composition in the receiver is not known.
    Response: We agree with the commenter that the required procedures 
to calculate uncontrolled emissions when a vessel is equipped with a 
process condenser should be corrected to reflect the condenser exit gas 
temperature and composition of the condensate. The following 
assumptions apply for calculating uncontrolled emissions from process 
vent from a process condenser:
    (1) For all condenser calculations one would use the condenser exit 
gas temperature and pressure as the reference conditions.
    (2) It should be assumed that the condenser exit vent gas is in 
equilibrium with the liquid condensate which is also leaving the 
condenser based on the exit gas temperature. Therefore, the calculated 
vapor pressure for each volatile component in the condensate would have 
approximately the same calculated partial pressure of the same 
component in the exit vent gas from the condenser.
    (3) Dalton's Law would be used to calculate the partial pressure of 
the noncondensable component (air, nitrogen, * * *) contained in the 
condenser exit vent gas. This is where the sum of all of the partial 
pressures is equal to the total system pressure and the partial 
pressure of the noncondensable component would be calculated by 
subtracting the sum of all volatile component vapor pressures from the 
total system pressure.
    (4) Material balance considerations should be taken into account 
for each component at the condenser. The amount of each component that 
enters the condenser should be approximately equal to the amount that 
is calculated to leave the condenser through the exit vapor stream and 
the exit condensate liquid stream.
    (5) The amount of each component that is emitted from the condenser 
should be determined first. The total HAP that are emitted from the 
condenser may then be calculated from the component emission totals. It 
is likely that many of the compounds that are emitted from the 
condenser may not be HAP but would need to be calculated as part of the 
overall condenser solution.
    In all but the simplest cases (single component systems) the 
solution to the condenser problem will require a numerical iteration as 
part of the basic procedure. We are changing the procedures for 
calculating emissions from condensers to be as technically correct as 
possible. This is important because uncontrolled emission estimates are 
used as a threshold for requiring installation and operation of control 
devices.
    Comment: As part of the proposed amendments, a new paragraph was 
added at 40 CFR 63.2460(b)(4) to require the use of procedures in 40 
CFR 63.1257(d)(3)(i)(B) to calculate uncontrolled batch process vent 
emissions from a vessel equipped with a process condenser. Three 
commenters noted that there are some batch process steps where a 
process condenser is used, but the required equations do not adequately 
estimate the emissions. The commenters cited the following as examples: 
intermittent vents from continuous distillation columns, maintenance 
purges, or regenerator operations. To estimate uncontrolled emissions 
for such steps, the commenters believe 40 CFR part 63, subpart FFFF 
should allow the use of engineering assessments in accordance with 40 
CFR 63.1257(d)(2)(ii) of the Pharmaceuticals Production NESHAP. 
According to one commenter, engineering assessments also should be 
allowed for emission episodes covered by the equations if the owner or 
operator can demonstrate to the Administrator that those methods are 
not appropriate.
    Response: We agree with the commenters that the specified equations 
do not address all possible types of emission episodes from process 
condensers, just as they do not address all possible types of emission 
episodes directly from process equipment. Therefore, we have modified 
40 CFR 63.2460(b)(4) in the final amendments to allow the use of 
engineering assessments for types of emission episodes not covered by 
the specified equations. However, the revised procedure for calculating 
condenser emissions will always apply. We also added the provision that 
allows engineering assessments covered by the equations in 40 CFR 
63.1257(d)(3)(i)(B) if you can demonstrate that those methods are not 
appropriate. These changes make the procedures for estimating 
uncontrolled emissions from process condensers consistent with the 
procedures for estimating uncontrolled emissions directly from process 
equipment.
    Comment: A proposed amendment in 40 CFR 63.2465(b) clarifies that 
uncontrolled hydrogen halide and halogen HAP emissions may be estimated 
using either the equations in 40 CFR 63.1257(d)(2)(i) or an engineering 
assessment in accordance with 40 CFR 63.1257(d)(2)(ii), whichever is 
appropriate. One commenter noted that in order to use an engineering 
assessment for emission episodes covered by the equations, 40 CFR 
63.1257(d)(2)(ii) requires a demonstration that the equations are not 
appropriate. The commenter asked if information to support the 
demonstration should be documented in the notification of compliance 
status report.
    Response: According to 40 CFR 63.1257(d)(2)(ii)(E), all information 
must be documented in the precompliance report. However, we

[[Page 40324]]

understand that the emission equations in 40 CFR 63.1257(d)(2)(i) were 
developed for organic HAP and decided that a demonstration that the 
equations are not appropriate for hydrogen halide and halogen HAP 
emissions would be an unnecessary burden. Therefore, 40 CFR 63.2465(b) 
of the final amendments specifies that the information to support an 
engineering assessment for estimating hydrogen halide and halogen HAP 
emissions must be submitted in the notification of compliance status 
report.

F. Monitoring Requirements

1. Absorbers
    Comment: Five commenters objected to the proposed amendments to the 
monitoring requirements for absorbers in 40 CFR 63.2450(k)(5). These 
amendments would require continuous monitoring of liquid and gas flow, 
and records of the liquid-to-gas ratio, in addition to the monitoring 
and recordkeeping required in 40 CFR 63.990(c)(1), 63.993(c)(1), and 
63.998(a)(2)(ii)(C). According to the commenters, the current 
monitoring requirements (liquid temperature and specific gravity) are 
sufficient to demonstrate compliance, and they believe we have not 
explained why these requirements are inadequate. They also noted that 
there is no precedent for the proposed monitoring (except for halogen 
scrubbers, for which flow monitoring is already required in 40 CFR 
63.994), and it would add significant burden and cost to monitoring 
absorbers. Therefore, the commenters believe the proposed amendments 
should not be finalized.
    Response: Our intent was to require liquid and gas flow monitoring 
only for absorbers where water is used as the scrubbing fluid. As the 
commenters pointed out, the rule already requires this monitoring for 
halogen scrubbers by referencing the requirements in 40 CFR 63.994. 
However, water can also be used to scrub organic compounds from an 
emission stream. We believe the same monitoring requirements that apply 
to halogen scrubbers should also apply to any other absorber that uses 
water as the scrubbing liquid. Therefore, 40 CFR 63.2450(k)(5) in the 
final amendments has been revised to require the liquid and gas flow 
monitoring only for absorbers that control organic compounds and use 
water as the scrubbing fluid.
2. Organic Monitoring Devices
    Comment: The proposed amendments added a new 40 CFR 63.2460(c)(9) 
to specify requirements for biofilters that are used as control devices 
for batch process vents. Section 63.2460(c)(9)(iii) specified 
requirements for temperature monitoring devices and organic monitoring 
devices. This section also indicated that general requirements for 
continuous emissions monitoring system(s) (CEMS) are specified in 40 
CFR 63.2450(j) and in Table 12 to subpart FFFF of 40 CFR part 63. The 
preamble to the proposed amendments explained that this rule language 
means the quality assurance/quality control and other requirements for 
CEMS in subpart A of 40 CFR part 63 would apply to organic monitoring 
devices. Three commenters disagreed with this statement. One of the 
commenters pointed out that a CEMS must provide a record of the 
emissions, whereas an organic monitoring device is required to provide 
an indication of concentration. As an example, this commenter noted 
that the monitored parameter for an organic monitoring device could be 
a calibrated indicator of HAP concentration such as the millivolts 
generated by a concentration sensor. According to another commenter, 
the references to CEMS in the amended explanations for citations in 
Table 12 to subpart FFFF of 40 CFR part 63 should be applicable only to 
CEMS that are used for compliance with the alternative standard in 40 
CFR 63.2505. Thus, the three commenters recommended removing the 
proposed changes from 40 CFR 63.2460(c)(9)(iii), Table 12 to subpart 
FFFF of 40 CFR part 63, and all associated preamble discussions.
    Response: The commenters' interpretation of the differences in 
requirements for CEMS and organic monitoring devices is correct. 
Requirements for CEMS were inappropriately applied to organic 
monitoring devices in 40 CFR 63.2460(c)(9)(iii) of the proposed 
amendments, and they have been removed from the final amendments. As a 
result of these changes, the use of an organic monitoring device with a 
biofilter is subject to the parameter monitoring requirements in 40 CFR 
part 63, subpart SS. All other organic monitoring devices, except those 
used with controls for wastewater systems, are also subject to the 
requirements in 40 CFR part 63, subpart SS. Organic monitoring devices 
used with controls for wastewater systems are subject to the similar 
parameter monitoring requirements in 40 CFR part 63, subpart G of the 
HON.
    We disagree with the comments regarding the proposed changes in 
Table 12 to subpart FFFF of 40 CFR part 63. Nothing in the rule