Document ID: EPA-HQ-OAR-2006-0534-0001
Agency: epa
Document Type: Proposed Rule
Title: Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Hospital/Medical/Infectious Waste Incinerators
Posted Date: 2007-02-06T05:00Z

[Federal Register: February 6, 2007 (Volume 72, Number 24)]
[Proposed Rules]               
[Page 5509-5550]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06fe07-20]                         

[[Page 5509]]

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Part II

Environmental Protection Agency

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40 CFR Part 60

Standards of Performance for New Stationary Sources and Emission 
Guidelines for Existing Sources: Hospital/Medical/Infectious Waste 
Incinerators; Proposed Rule

[[Page 5510]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2006-0534; FRL-8274-9]
RIN 2060-A004

 
Standards of Performance for New Stationary Sources and Emission 
Guidelines for Existing Sources: Hospital/Medical/Infectious Waste 
Incinerators

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: On September 15, 1997, EPA adopted new source performance 
standards (NSPS) and emission guidelines for hospital/medical/
infectious waste incinerators (HMIWI). The NSPS and emission guidelines 
were established under sections 111 and 129 of the Clean Air Act (CAA). 
On November 14, 1997, the Sierra Club and the Natural Resources Defense 
Council (Sierra Club) filed suit in the U.S. Court of Appeals for the 
District of Columbia Circuit (the Court) challenging EPA's methodology 
for adopting the regulations. On March 2, 1999, the Court issued its 
opinion. The Court remanded the rule to EPA for further explanation of 
the Agency's reasoning in determining the minimum regulatory ``floors'' 
for new and existing HMIWI. The Court did not vacate the regulations, 
so the NSPS and emission guidelines remained in effect during the 
remand and were fully implemented by September 2002. This action 
provides EPA's proposed response to the questions raised in the Court's 
remand.
    Section 129(a)(5) of the CAA requires EPA to review and, if 
appropriate, revise the NSPS and emission guidelines every 5 years. In 
this action, EPA also is proposing our response to this 5-year review, 
which would revise the emission limits in the NSPS and emission 
guidelines to reflect the levels of performance actually achieved by 
the emission controls installed to meet the emission limits set forth 
in the September 15, 1997, NSPS and emission guidelines.

DATES: Comments. Comments must be received on or before April 9, 2007. 
Under the Paperwork Reduction Act, comments on the information 
collection provisions must be received by the Office of Management and 
Budget (OMB) on or before March 8, 2007. Because of the need to resolve 
the issues raised in this action in a timely manner, EPA will not grant 
requests for extensions beyond these dates.
    Public Hearing. If anyone contacts EPA by February 26, 2007 
requesting to speak at a public hearing, EPA will hold a public hearing 
on March 8, 2007. If you are interested in attending the public 
hearing, contact Ms. Pamela Garrett at (919) 541-7966 to verify that a 
hearing will be held.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2006-0534, by one of the following methods:
    http://www.regulations.gov: Follow the on-line instructions for submitting 

comments.
    E-mail: Send your comments via electronic mail to 
a-and-r-Docket@epa.gov, Attention Docket ID No. EPA-HQ-OAR-2006-0534.

    Facsimile: Fax your comments to (202) 566-1741, Attention Docket ID 
No. EPA-HQ-OAR-2006-0534.
    Mail: Send your comments to: EPA Docket Center (EPA/DC), 
Environmental Protection Agency, Mailcode 6102T, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460, Attention Docket ID No. EPA-HQ-OAR-
2006-0534.
    Hand Delivery: Deliver your comments to: EPA Docket Center (EPA/
DC), EPA West Building, Room 3334, 1301 Constitution Ave., NW., 
Washington, DC 20460, Attention Docket ID No. EPA-HQ-OAR-2006-0534. 
Such deliveries are accepted only during the normal hours of operation 
(8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays), and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2006-0534. The EPA's policy is that all comments received will be 
included in the public docket and may be made available online at 
http://www.regulations.gov, including any personal information provided, 

unless the comment includes information claimed to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Do not submit information that you consider to 
be CBI or otherwise protected through http://www.regulations.gov or e-mail. 

The http://www.regulations.gov Web site is an ``anonymous access'' system, 

which means EPA will not know your identity or contact information 
unless you provide it in the body of your comment. If you send an e-
mail comment directly to EPA without going through http://www.regulations.gov, 

your e-mail address will be automatically captured and included as part 
of the comment that is placed in the public docket and made available 
on the Internet. If you submit an electronic comment, EPA recommends 
that you include your name and other contact information in the body of 
your comment and with any disk or CD-ROM you submit. If EPA cannot read 
your comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses.
    Public Hearing: If a public hearing is held, it will be held at 
EPA's Campus located at 109 T.W. Alexander Drive in Research Triangle 
Park, NC, or an alternate site nearby. Persons interested in presenting 
oral testimony must contact Ms. Pamela Garrett at (919) 541-7966 at 
least 2 days in advance of the hearing.
    Docket: EPA has established a docket for this action under Docket 
ID No. EPA-HQ-OAR-2006-0534 and Legacy Docket ID No. A-91-61. All 
documents in the docket are listed in the http://www.regulations.gov index. 

Although listed in the index, some information is not publicly 
available, e.g., CBI or other information whose disclosure is 
restricted by statute. Certain other material, such as copyrighted 
material, will be publicly available only in hard copy form. Publicly 
available docket materials are available either electronically at 
http://www.regulations.gov or in hard copy at the EPA Docket Center EPA/DC, 

EPA West, Room 3334, 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 EPA 
Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Ms. Mary Johnson, Energy Strategies 
Group, Sector Policies and Programs Division (D243-01), Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711; 
telephone number: (919) 541-5025; fax number: (919) 541-5450; e-mail 
address: johnson.mary@epa.gov.

SUPPLEMENTARY INFORMATION: Organization of This Document. The following 
outline is provided to aid in locating information in this preamble.
I. General Information
    A. Does the proposed action apply to me?
    B. What should I consider as I prepare my comments?
II. Background
III. Summary
    A. Litigation and Proposed Remand Response

[[Page 5511]]

    B. Proposed Amendments (CAA Section 129(a)(5) 5-Year Review)
IV. Rationale
    A. Rationale for the Proposed Response to the Remand
    B. Rationale for the Proposed Amendments (CAA Section 129(a)(5) 
5-Year Review)
V. Impacts of the Proposed Action for Existing Units
    A. What are the primary air impacts?
    B. What are the water and solid waste impacts?
    C. What are the energy impacts?
    D. What are the secondary air impacts?
    E. What are the cost and economic impacts?
VI. Impacts of the Proposed Action for New Units
VII. Relationship of the Proposed Action to Section 112(c)(6) of the 
CAA
VIII. 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

I. General Information

A. Does the proposed action apply to me?

    Regulated Entities. Categories and entities potentially affected by 
the proposed action are those which operate HMIWI. The NSPS and 
emission guidelines for HMIWI affect the following categories of 
sources:

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                                                                                                 Examples of
                   Category                                     NAICS Code                       potentially
                                                                                              regulated entities
----------------------------------------------------------------------------------------------------------------
Industry.....................................  622110, 622310, 325411, 325412, 562213,       Private hospitals,
                                                611310.                                       other health care
                                                                                              facilities,
                                                                                              commercial
                                                                                              research
                                                                                              laboratories,
                                                                                              commercial waste
                                                                                              disposal
                                                                                              companies, private
                                                                                              universities.
Federal Government...........................  622110, 541710, 928110......................  Federal hospitals,
                                                                                              other health care
                                                                                              facilities, public
                                                                                              health service,
                                                                                              armed services.
State/local/Tribal Government................  622110, 562213, 611310......................  State/local
                                                                                              hospitals, other
                                                                                              health care
                                                                                              facilities, State/
                                                                                              local waste
                                                                                              disposal services,
                                                                                              State
                                                                                              universities.
----------------------------------------------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by the 
proposed action. To determine whether your facility would be affected 
by the proposed action, you should examine the applicability criteria 
in 40 CFR 60.50c of subpart Ec and 40 CFR 60.32e of subpart Ce. If you 
have any questions regarding the applicability of the proposed action 
to a particular entity, contact the person listed in the preceding FOR 
FURTHER INFORMATION CONTACT section.

B. What should I consider as I prepare my comments?

1. Submitting CBI
    Do not submit information that you consider to be CBI 
electronically through http://www.regulations.gov or e-mail. Send or deliver 

information identified as CBI to only the following address: Ms. Mary 
Johnson, c/o OAQPS Document Control Officer (Room C404-02), U.S. EPA, 
Research Triangle Park, NC 27711, Attention Docket ID No. EPA-HQ-OAR-
2006-0534. Clearly mark the part or all of the information that you 
claim to be CBI. For CBI information in a disk or CD ROM that you mail 
to EPA, mark the outside of the disk or CD ROM as CBI and then identify 
electronically within the disk or CD ROM the specific information that 
is claimed as CBI. In addition to one complete version of the comment 
that includes information claimed as CBI, a copy of the comment that 
does not contain the information claimed as CBI must be submitted for 
inclusion in the public docket. Information marked as CBI will not be 
disclosed except in accordance with procedures set forth in 40 CFR part 
2.
    If you have any questions about CBI or the procedures for claiming 
CBI, please consult the person identified in the FOR FURTHER 
INFORMATION CONTACT section.
2. Tips for Preparing Your Comments
    When submitting comments, remember to:
    a. Identify the rulemaking by docket number and other identifying 
information (subject heading, Federal Register date and page number).
    b. Follow directions. The EPA may ask you to respond to specific 
questions or organize comments by referencing a Code of Federal 
Regulations (CFR) part or section number.
    c. Explain why you agree or disagree; suggest alternatives and 
substitute language for your requested changes.
    d. Describe any assumptions and provide any technical information 
and/or data that you used.
    e. If you estimate potential costs or burdens, explain how you 
arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
    f. Provide specific examples to illustrate your concerns, and 
suggest alternatives.
    g. Explain your views as clearly as possible, avoiding the use of 
profanity or personal threats.
    h. Make sure to submit your comments by the comment period deadline 
identified in the preceding section titled DATES.
3. Docket
    The docket number for the proposed action regarding the HMIWI NSPS 
(40 CFR part 60, subpart Ec) and emission guidelines (40 CFR part 60, 
subpart Ce) is Docket ID No. EPA-HQ-OAR-2006-0534.
4. Worldwide Web (WWW)
    In addition to being available in the docket, an electronic copy of 
this proposed action is available on the WWW through the Technology 
Transfer Network Web site (TTN Web). Following signature, EPA posted a 
copy of the proposed action on the TTN's policy and guidance page for 
newly proposed or promulgated rules at http://www.epa.gov/ttn/oarpg. 

The TTN provides information and technology exchange in various areas 
of air pollution control.

II. Background

    Section 129 of the CAA, entitled ``Solid Waste Combustion,'' 
requires EPA to develop and adopt NSPS and emission guidelines for 
solid waste incineration units pursuant to CAA sections 111 and 129. 
Sections 111(b) and 129(a) of the CAA (NSPS program) address emissions 
from new HMIWI units, and CAA sections 111(d) and 129(b) (emission 
guidelines program) address emissions from existing HMIWI units. The 
NSPS are directly enforceable Federal regulations. The emission 
guidelines are not directly enforceable but, rather, are implemented by 
State air pollution control agencies through sections 111(d)/129 State 
plans.
    An HMIWI is defined as any device used to burn hospital waste or 
medical/

[[Page 5512]]

infectious waste. Hospital waste means discards generated at a 
hospital, and medical/infectious waste means any waste generated in the 
diagnosis, treatment, or immunization of human beings or animals, in 
research pertaining thereto, or in the production or testing of 
biologicals (e.g., vaccines, cultures, blood or blood products, human 
pathological waste, sharps). Hospital/medical/infectious waste does not 
include household waste, hazardous waste, or human and animal remains 
not generated as medical waste. An HMIWI typically is a small, dual-
chamber incinerator that burns about 800 pounds per hour (lb/hr) of 
waste. Smaller units burn as little as 13 lb/hr while larger units burn 
as much as 3,700 lb/hr.
    Incineration of hospital/medical/infectious waste causes the 
release of a wide array of air pollutants, some of which exist in the 
waste feed material and are released unchanged during combustion, and 
some of which are generated as a result of the combustion process 
itself. These pollutants include particulate matter (PM); heavy metals, 
including lead (Pb), cadmium (Cd), and mercury (Hg); toxic organics, 
including chlorinated dibenzo-p-dioxins/dibenzofurans (CDD/CDF); carbon 
monoxide (CO); nitrogen oxides (NOX); and acid gases, 
including hydrogen chloride (HCl) and sulfur dioxide (SO2). 
In addition to the use of good combustion control practices, HMIWI 
units are typically controlled by wet scrubbers or dry sorbent 
injection fabric filters (dry scrubbers).
    Combustion control includes the proper design, construction, 
operation, and maintenance of HMIWI to destroy or prevent the formation 
of air pollutants prior to their release to the atmosphere. Test data 
indicate that as secondary chamber residence time and temperature 
increase, emissions decrease. Combustion control is most effective in 
reducing CDD/CDF, PM, and CO emissions. The 0.25-second combustion 
level includes a minimum secondary chamber temperature of 1700 [deg]F 
and a 0.25-second secondary chamber residence time. These combustion 
conditions are typical of older HMIWI. The 1-second combustion level 
includes a minimum secondary chamber temperature of 1700 [deg]F and 
residence time of 1 second. These combustion conditions are typical of 
newer HMIWI. Compared to 0.25-second combustion, 1-second combustion 
will achieve substantial reductions in CDD/CDF and CO emissions, and 
will provide some control of PM, but will not reduce emissions of acid 
gases (HCl and SO2), NOX, or metals (Pb, Cd, and 
Hg). The 2-second combustion level includes a minimum secondary chamber 
temperature of 1800 [deg]F and residence time of 2 seconds. These 
combustion conditions will provide additional control of CDD/CDF, CO, 
and PM, but will not reduce emissions of acid gases (HCl and 
SO2), NOX, or metals (Pb, Cd, and Hg). The 2-
second combustion conditions are considered to be the best level of 
combustion control (i.e., good combustion) that is applied to HMIWI. 
Wet scrubbers and dry scrubbers provide control of PM, CDD/CDF, HCl, 
and metals, but do not influence CO, SO2 (at the low 
concentrations emitted by HMIWI units), or NOX; in fact, 
there are no technologies currently used by HMIWI that will 
consistently reduce SO2 or NOX emissions. (See 
Legacy Docket ID No. A-91-61, item II-A-111; 60 FR 10669, 10671-10677; 
and 61 FR 31742-31743.)
    On September 15, 1997, EPA adopted NSPS (40 CFR part 60, subpart 
Ec) and emission guidelines (40 CFR part 60, subpart Ce) for entities 
which operate HMIWI. The NSPS and emission guidelines are designed to 
reduce air pollution emitted from new and existing HMIWI, including 
HCl, CO, Pb, Cd, Hg, PM, CDD/CDF (total, or 2,3,7,8-tetrachlorinated 
dibenzo-p-dioxin toxic equivalent (TEQ)), NOX, SO2, and 
opacity. The NSPS apply to HMIWI for which construction began after 
June 20, 1996, or for which modification began after March 16, 1998. 
The NSPS became effective on March 16, 1998, and its requirements apply 
as of that date or at start-up of a HMIWI unit, whichever is later. The 
emission guidelines apply to HMIWI for which construction began on or 
before June 20, 1996, and required compliance by September 2002.
    CAA section 129 requires EPA to establish technology-based emission 
standards that reflect levels of control EPA determines are achievable 
for new and existing units, after considering costs, non-air quality 
health and environmental impacts, and energy requirements associated 
with the implementation of the standards.
    In setting forth the methodology EPA must use to establish the 
technology-based performance standards and emissions guidelines, CAA 
section 129(a)(2) provides that standards ``applicable to solid waste 
incineration units promulgated under section 111 and this section shall 
reflect the maximum degree of reduction in emissions of [certain listed 
air pollutants] that the Administrator, taking into consideration the 
cost of achieving such emission reduction, and any non-air quality 
health and environmental impacts and energy requirements, determines is 
achievable for new and existing units in each category.'' This level of 
control is referred to as a maximum achievable control technology, or 
MACT standard.
    In promulgating a MACT standard, EPA must first calculate the 
minimum stringency levels for new and existing solid waste incineration 
units in a category, generally based on levels of emissions control 
achieved or required to be achieved by the subject units. The minimum 
level of stringency is called the MACT floor, and CAA section 129(a)(2) 
provides that the ``degree of reduction in emissions that is deemed 
achievable for new units in a category shall not be less stringent than 
the emissions control that is achieved in practice by the best 
controlled similar unit, as determined by the Administrator. Emissions 
standards for existing units in a category may be less stringent than 
standards for new units in the same category but shall not be less 
stringent than the average emissions limitation achieved by the best 
performing 12 percent of units in the category.''
    The minimum stringency requirements form the first and least 
stringent regulatory option EPA must consider in the determination of 
MACT for a source category. EPA must also determine whether to control 
emissions ``beyond the floor,'' after considering the costs, non-air 
quality health and environmental impacts, and energy requirements of 
such more stringent control. These are the two steps EPA took in the 
1997 HMIWI rulemaking. Finally, every 5 years after adopting a MACT 
standard under section 129, CAA section 129(a)(5) requires EPA to 
review and, if appropriate, revise the incinerator standards. In 
addition to responding to the Court's remand in Sierra Club v. EPA, 167 
F.3d 658 (D.C. Cir. 1999), this proposed action includes our first set 
of proposed revisions to the HMIWI standards, also known as the 5-year 
review.

III. Summary

A. Litigation and Proposed Remand Response

1. What was EPA's general methodology for determining MACT?
    The methodology used to determine MACT is similar for source 
categories under sections 112 and 129 of the CAA. However, because each 
source category is unique and the data available to determine the 
performance capabilities of technology can vary from one source 
category to another, the basic methodology must be adapted to fit the

[[Page 5513]]

source category in question. As the Court pointed out in the HMIWI 
litigation, it ``generally defer[s] to an agency's decision to proceed 
on the basis of imperfect scientific information, rather than to 
`invest the resources to conduct the perfect study.' '' Sierra Club v. 
EPA, 167 F.3d at 662.
    In general, all MACT analyses involve an assessment of the air 
pollution control systems or technologies used by the better performing 
units in a source category. The technology assessment can be based 
solely on actual emissions data, on knowledge of the air pollution 
control in place in combination with actual emissions data, or on State 
regulatory requirements, which give an indication of the actual 
performance of the regulated units. For each source category, the 
assessment of the technology involves a review of actual emissions data 
with an appropriate accounting for emissions variability. Where there 
is more than one method or technology to control emissions, the 
analysis results in a series of potential regulations (called 
regulatory options), one of which is selected as MACT.
    The first regulatory option considered by EPA must be at least as 
stringent as the CAA's minimum stringency requirements. However, MACT 
is not necessarily the least stringent regulatory option. EPA must 
examine more stringent regulatory options to determine MACT. Unlike the 
minimum stringency requirements, EPA must consider various impacts of 
the more stringent regulatory options in determining MACT. Only if the 
more stringent regulatory options are considered to have unreasonable 
impacts does EPA select the first ``floor-based'' regulatory option as 
MACT.
    As stated earlier, the CAA requires that MACT for new sources be no 
less stringent than the emissions control achieved in practice by the 
best controlled similar unit. After EPA's assessment of technology, EPA 
determines the best control currently in use for a given pollutant and 
establishes one potential regulatory option at the emission level 
achievable by that control. More stringent potential regulatory options 
might reflect controls used on other sources that could be applied to 
the source category in question.
    For existing sources, the CAA requires that MACT be no less 
stringent than the average emissions limitation achieved by the best 
performing 12 percent of units in a source category. EPA must determine 
some measure of the average emissions limitation achieved by the best 
performing 12 percent of units to form the least stringent regulatory 
option. Sometimes, a direct calculation of the actual emissions values 
from the best performing 12 percent of sources provides the basis for 
this regulatory option. More often, EPA determines the technology used 
by the average source in the best performing 12 percent of sources and 
establishes the floor based on the technology assessment for that 
average source. More stringent regulatory options reflect other 
technologies capable of achieving better performance.
2. What was EPA's methodology in the 1997 HMIWI rulemaking?
    On February 27, 1995, EPA published a notice of proposed rulemaking 
regarding emissions standards for HMIWI units (60 FR 10654). The 
proposal was the result of several years of reviewing available 
information. During the public comment period for the proposal, EPA 
received over 700 letters, some of which contained new information or 
indicated that the commenters were in the process of gathering more 
information for EPA to consider. The new information led EPA to 
consider the need for numerous changes to the proposed rule, and on 
June 20, 1996, the Agency published a re-proposal (61 FR 31736). 
Following an additional public comment period, EPA published the final 
rule on September 15, 1997 (62 FR 48348).
    During the data-gathering phase of developing the 1995 proposal, 
EPA found it difficult to obtain an accurate count of the thousands of 
HMIWI units nationwide, or to find HMIWI units with add-on air 
pollution control systems in place. A few HMIWI units with combustion 
control were tested to assess performance of combustion control in 
reducing emissions. One unit with a wet scrubber, and a few units with 
dry scrubbing systems were tested to determine performance capabilities 
of add-on controls. (See 61 FR 31738.)
    Altogether, data were available from only 7 out of the estimated 
then-operating 3,700 existing HMIWI units (60 FR 10674). Because EPA 
was under a court-ordered deadline to propose and adopt standards for 
HMIWI that did not provide sufficient time to collect more actual 
emissions data (see consent decree entered in Sierra Club v. EPA, Nos. 
CV-92-2093 and CV-93-0284 (E.D.N.Y.)), EPA proceeded to develop the 
regulations with the existing data, as described below. However, EPA 
specifically requested comment on EPA's MACT determinations and on 
EPA's conclusions about the performance capabilities of air pollution 
control technologies on HMIWI in light of the relatively small database 
(60 FR 10686).
    a. EPA's Methodology for New HMIWI. In determining the least 
stringent regulatory option allowed by the CAA for new HMIWI, EPA first 
examined the data available for various air pollution control 
technologies applied to HMIWI to determine the performance capabilities 
of the technologies (i.e., the achievable emission limitations) (60 FR 
10671-73, 61 FR 31741-43). To determine the performance capabilities, 
EPA grouped all of the test data by control technology and established 
the numerical value for the achievable emission limitations somewhat 
higher than the highest test data point for each particular control 
technology. (See Legacy Docket ID No. A-91-61, items IV-B-46, 47, 48, 
and 49.) Following the determination of performance capability, EPA 
identified the best control technology for each air pollutant for each 
subcategory of HMIWI, and established the numerical values for the 
least stringent regulatory option at the achievable emission limitation 
associated with that particular control technology. (See 60 FR 10673; 
Legacy Docket ID No. A-91-61, item IV-B-38; 61 FR 31745-46.) Other, 
more stringent, regulatory options were developed reflecting the actual 
performance of other, more effective, control technologies (61 FR 
31766-68).
    As stated in the 1996 re-proposal, the least stringent regulatory 
option for new large HMIWI units (units with maximum waste burning 
capacity of more than 500 lb/hr) was based on good combustion (i.e., 2-
second combustion level) and a combination of two control technologies, 
high-efficiency wet scrubbers and dry injection/fabric filter dry 
scrubbers with carbon (61 FR 31746). New medium units (units with 
maximum waste burning capacity of more than 200 lb/hr but less than or 
equal to 500 lb/hr) would need to use good combustion and a combination 
of two control technologies, high-efficiency wet scrubbers and dry 
injection/fabric filter dry scrubbers without carbon, to meet the least 
stringent regulatory option. Id. New small units (units with maximum 
waste burning capacity of less than or equal to 200 lb/hr) would need 
to use good combustion and a moderate-efficiency wet scrubber to meet 
the least stringent regulatory option. Id.
    In EPA's final standards promulgated in 1997, EPA selected an 
overall more stringent regulatory option for new HMIWI (62 FR 48365). 
The final standards were based on emission limits achievable with good 
combustion and a

[[Page 5514]]

moderate-efficiency wet scrubber for new small HMIWI, and good 
combustion and a combined dry/wet control system with carbon for new 
medium and large HMIWI. Id. These standards reflected the MACT floor 
emissions levels for new small and large HMIWI, but were more stringent 
than the MACT floor for new medium HMIWI. Id. EPA estimated that the 
standards would reduce emissions from these units of HCl by up to 98 
percent, PM and Pb by up to 92 percent, Cd by up to 91 percent, CDD/CDF 
by up to 87 percent, Hg by up to 74 percent, and CO, SO2, 
and NOX by up to 52 percent (62 FR 48366).
    b. EPA's Methodology for Existing HMIWI. For existing units, EPA 
did not have sufficient emissions data to fully characterize the actual 
emissions performance of the best performing 12 percent of existing 
HMIWI, and, based exclusively on such data, EPA did not have a clear 
indication of the technology used by the best 12 percent of units. As a 
result, EPA used emission limits included in State regulations and 
State-issued permits (hereinafter referred to as regulatory limits) as 
surrogate information to determine emissions limitations achieved by 
the best performing 12 percent of units in each subcategory (60 FR 
10674). EPA believed this information could be expected to reliably 
reflect levels of performance achieved on a continuous basis by better-
controlled units that must meet these limits or risk violating 
enforceable requirements. EPA assumed that all HMIWI were achieving 
their regulatory limits (60 FR 10674). Where there were regulatory 
limits for more than 12 percent of units in a subcategory, the 
regulatory limits were ranked from the most stringent to least 
stringent, and the average of the regulatory limits for the top 12 
percent of units in the subcategory was calculated. Id.; 61 FR 31744-
45. Where the number of units subject to specific emissions limitations 
did not comprise 12 percent of the population in a subcategory, EPA 
assumed those units with regulatory limits were the best performing 
units, and the remaining units in the top 12 percent were assigned an 
emission value associated with ``combustion control.'' (See 60 FR 
10674; 61 FR 31745; Legacy Docket ID No. A-91-61, item IV-B-24 at 2.) 
In previous Federal Register notices regarding HMIWI (60 FR 10654, 61 
FR 31736, and 62 FR 48348), this level of control was referred to as 
``uncontrolled,'' which is misleading because sources with combustion 
control emit lesser amounts of CDD/CDF, CO, and PM. In the latter 
situation described above, the average of the regulatory limits plus 
enough combustion-controlled emission values to account for 12 percent 
of units in the subcategory was calculated. (See Legacy Docket ID No. 
A-91-61, item IV-B-24 at 2-4.)
    After calculating the averages of regulatory limits and combustion-
controlled emission values, EPA examined the resulting calculated 
values to determine what level of air pollution control would be needed 
to meet the calculated average values. (See 60 FR 10675-78; 61 FR 
31755-56.) For many pollutants, the calculated averages presented no 
clear indication of the type of air pollution control used by the best 
performing units. However, the calculated values for three key 
pollutants, PM, CO, and HCl, did provide a good indication of the type 
of air pollution control used on the best performing 12 percent of 
units. The level of air pollution control associated with the 
calculated average values for PM, CO, and HCl formed the technical 
basis of the least stringent regulatory option considered by EPA (61 FR 
31756, Table 13). The emission limitations assigned to each pollutant 
reflected the actual performance of the technology on which they were 
based. Finally, EPA developed a series of regulatory options based on 
progressively more stringent technologies and assigned emission 
limitations to each regulatory option based on the actual performance 
capabilities of the technologies (61 FR 31757, Table 14).
    As stated in the 1996 re-proposal, large existing units would need 
to use good combustion and a high-efficiency wet scrubber to meet the 
least stringent regulatory option, while medium existing units would 
need to use good combustion and a moderate-efficiency wet scrubber, 
although dry scrubbers could also be used with good combustion at large 
and medium existing units (61 FR 31745). EPA further stated that its 
inclination was to establish emission limitations for large and medium 
existing units based on regulatory options representing the MACT floors 
(61 FR 31778). Small existing units would need only to use good 
combustion practices to meet the regulatory option representing the 
MACT floor (61 FR 31745). With respect to small existing units, EPA 
stated that it had no inclination with regard to which regulatory 
option should be used to establish emission limitations and requested 
comment on requiring use of good combustion and a low-efficiency wet 
scrubber (61 FR 31778-79).
    In EPA's final standards promulgated in 1997, EPA selected an 
overall more stringent regulatory option for existing HMIWI (62 FR 
48371). The final standards were based on emission limits achievable 
with good combustion and a low-efficiency wet scrubber for most 
existing small HMIWI, good combustion and a moderate-efficiency wet 
scrubber for existing medium HMIWI, and good combustion and a high-
efficiency wet scrubber for existing large HMIWI (62 FR 48371). The 
final standards allow small HMIWI that meet certain rural criteria to 
meet emissions limits achievable with good combustion alone. Id. These 
standards reflected the MACT floor emissions levels for existing small 
HMIWI meeting rural criteria, medium HMIWI, and large HMIWI, but were 
more stringent than the MACT floor for most existing small HMIWI (i.e., 
non-rural) (62 FR 48371-72). The final standards for existing medium 
and large HMIWI were structured so that either a dry scrubber or a wet 
scrubber could be used to achieve the emission limits. EPA estimated 
that the final emission guidelines would reduce emissions of CDD/CDF by 
up to 97 percent, Hg by up to 95 percent, PM by up to 92 percent, Pb by 
up to 87 percent, Cd by up to 84 percent, CO by up to 82 percent, HCl 
by up to 98 percent, and SO2 and NOX by up to 30 
percent (62 FR 48372). Table 1 of this preamble summarizes the emission 
limits for the NSPS and emission guidelines promulgated in 1997.

                                Table 1.--Summary of Promulgated Emission Limits
----------------------------------------------------------------------------------------------------------------
                                                        Limit for existing
        Pollutant (units)             Unit Size \1\          HMIWI \2\             Limit for new HMIWI \2\
----------------------------------------------------------------------------------------------------------------
HCl (parts per million by volume  L, M, S.............  100 or 93%          15 or 99% reduction.
 (ppmv)).                                                reduction.
                                  SR..................  3,100.............  N/A.\3\
CO (ppmv).......................  L, M, S.............  40................  40
                                  SR..................  40................  N/A.
Pb (milligrams per dry standard   L, M................  1.2 or 70%          0.07 or 98% reduction.\3\
 cubic meter (mg/dscm)).                                 reduction.

[[Page 5515]]

                                  S...................  1.2 or 70%          1.2 or 70% reduction.
                                                         reduction.
                                  SR..................  10................  N/A.
Cd (mg/dscm)....................  L, M................  0.16 or 65%         0.04 or 90% reduction.
                                                         reduction.
                                  S...................  0.16 or 65%         0.16 or 65% reduction.
                                                         reduction.
                                  SR..................  4.................  N/A.
Hg (mg/dscm)....................  L, M, S.............  0.55 or 85%         0.55 or 85% reduction.
                                                         reduction.
                                  SR..................  7.5...............  N/A.
PM (grains per dry standard       L...................  0.015.............  0.015
 cubic foot (gr/dscf)).
                                  M...................  0.03..............  0.015
                                  S...................  0.05..............  0.03.
                                  SR..................  0.086.............  N/A.
CDD/CDF, total (nanograms per     L, M................  125...............  25
 dry standard cubic meter (ng/
 dscm)).
                                  S...................  125...............  125
                                  SR..................  800...............  N/A.
CDD/CDF, TEQ (ng/dscm)..........  L, M................  2.3...............  0.6
                                  S...................  2.3...............  2.3
                                  SR..................  15................  N/A.
NOX (ppmv)......................  L, M, S.............  250...............  250
                                  SR..................  250...............  N/A.
SO2 (ppmv)......................  L, M, S.............  55................  55
                                  SR..................  55................  N/A.
----------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small; SR = Small Rural
\2\ All emission limits are measured at 7 percent oxygen.
\3\ Not applicable.

    c. Compliance by HMIWI. At the time of promulgation (September 
1997), EPA estimated that there were approximately 2,400 HMIWI 
operating in the United States. Those units combusted approximately 830 
thousand tons of hospital/medical/infectious waste annually. Of those 
existing HMIWI, about 48 percent were small units, 29 percent were 
medium units, and 20 percent were large units. About 3 percent of the 
HMIWI were commercial units. EPA projected that no new small or medium 
HMIWI would be constructed, and that up to 60 new large units and 10 
new commercial units would be constructed.
    After shutdown of approximately 97 percent of the 2,400 HMIWI that 
were operating in 1997, there are currently 72 existing HMIWI at 67 
facilities. Additionally, only 4 new HMIWI at 3 facilities began 
operation following the 1997 rulemaking. These 76 existing and new 
units are estimated to combust approximately 165 thousand tons of waste 
annually. Of the 72 existing HMIWI subject to the emission guidelines, 
44 are large units, 20 are medium units, and 8 are small units (6 of 
which meet the rural criteria). Twenty-one percent of the existing 
HMIWI are commercially owned. Of the four new HMIWI, three are large 
units, and one is a medium unit. Two of the new units are county-owned 
but accept waste from other sources, similar to commercial units. The 
actual emissions reductions achieved as a result of implementation of 
the standards exceeded the 1997 projections for all nine of the 
regulated pollutants. A comparison of the estimated pollutant 
reductions versus the actual reductions is presented in Table 2 of this 
preamble.

  Table 2.--Comparison of Estimated Pollutant Reductions Versus Actual
                          Pollutant Reductions
------------------------------------------------------------------------
                                       Estimated
                                       emissions       Actual emissions
            Pollutant                 reduction,      reduction, percent
                                        percent               \1\
------------------------------------------------------------------------
HCl.............................  98................                99.2
CO..............................  75 to 82..........                98.1
Pb..............................  80 to 87..........                98.7
Cd..............................  75 to 84..........                99.0
Hg..............................  93 to 95..........                99.0
PM..............................  88 to 92..........                98.1
CDD/CDF, total..................  96 to 97..........                99.5
CDD/CDF, TEQ....................  95 to 97..........                99.6
NOX.............................  0 to 30...........                70.6
SO2.............................  0 to 30...........                92.6
------------------------------------------------------------------------
\1\ Reflects the effect of unit shutdowns as well as the effect of
  compliance with the promulgated standards.

3. What was the Sierra Club's challenge?
    On November 14, 1997, the Sierra Club and the Natural Resources 
Defense Council (Sierra Club) filed suit in the U.S. Court of Appeals 
for the District of Columbia Circuit (the Court). The Sierra Club 
claimed that EPA had violated CAA section 129 by setting emission 
standards for HMIWI under CAA sections 129 and 111 that are less 
stringent than the statutory minimum stringency required by section 
129(a)(2); that EPA had violated section 129 by not including mandatory 
pollution prevention or waste minimization requirements in the HMIWI 
standards; and that EPA had not adequately considered the non-air 
quality health and environmental impacts of the standards. For new 
units, the Sierra

[[Page 5516]]

Club argued that to satisfy the statutory phrase ``best controlled 
similar unit'' in CAA section 129(a)(2), EPA should have identified the 
single best performing unit in each subcategory and based the MACT 
floor for that subcategory on that particular unit's performance, 
rather than consider the performance of other units using the same 
technology. The Sierra Club also argued that EPA erroneously based the 
new unit floors on the emissions of the worst performing unit using a 
particular technology. Regarding existing units, the Sierra Club 
claimed that the plain meaning of CAA section 129(a)(2)'s words, 
``average emissions limitation achieved by the best performing 12 
percent of units,'' precludes the use of regulatory data, and claimed 
that the legislative history of section 129(a)(2) reflects 
congressional intent to prohibit EPA from relying on regulatory data. 
Moreover, the Sierra Club claimed that, for HMIWI, using regulatory 
data was impossible because such data existed for fewer than 12 percent 
of units, and because doing so would impermissibly import an 
achievability requirement into the unit floor determination. Finally, 
the Sierra Club argued that EPA failed to require HMIWI units to 
undertake programs to reduce the Hg and chlorinated plastic in their 
waste streams, in violation of CAA section 129(a)(3), and that EPA 
failed to consider the fact that CDD/CDF and Hg from HMIWI can 
contaminate water, sediment, and soil, and can bioaccumulate in food, 
in violation of the CAA's requirement that EPA consider non-air quality 
impacts of setting HMIWI emissions standards.
4. What was the Court's ruling?
    On March 2, 1999, the Court issued its opinion in Sierra Club v. 
EPA, 167 F.3d 658 (D.C. Cir. 1999). While the Court rejected the Sierra 
Club's claims regarding pollution prevention and non-air quality 
impacts, and rejected the Sierra Club's statutory arguments under CAA 
section 129, the Court remanded the rule to EPA for further explanation 
regarding how EPA derived the MACT floors for new and existing HMIWI 
units. Furthermore, the Court did not vacate the regulations, stating 
that ``[i]t is possible that EPA may be able to explain [EPA's basis 
for the standards]'' in response to the concerns raised by the Court. 
Id., at 664. The regulations remain in effect during the remand.
    a. The Court's Ruling on New Units. In response to the Sierra 
Club's claims regarding EPA's treatment of new units, the Court opined 
that ``EPA would be justified in setting the floors at a level that is 
a reasonable estimate of the performance of the `best controlled 
similar unit' under the worst reasonably foreseeable circumstances [* * 
*]. It is reasonable to suppose that if an emissions standard is as 
stringent as `the emissions control that is achieved in practice' by a 
particular unit, then that particular unit will not violate the 
standard. This only results if `achieved in practice' is interpreted to 
mean `achieved under the worst foreseeable circumstances.' In National 
Lime Ass'n v. EPA, 627 F.2d 416, 431 n. 46 (D.C. Cir. 1980), we said 
that where a statute requires that a standard be `achievable,' it must 
be achievable `under most adverse circumstances which can reasonably be 
expected to recur.' The same principle should apply when a standard is 
to be derived from the operating characteristics of a particular 
unit.'' Sierra Club v. EPA, 167 F.3d at 665. Thus, the Court refused to 
embrace the Sierra Club's interpretation of CAA section 129(a)(2) as 
requiring EPA to base the MACT floor on only the lowest emissions data 
points observed (i.e., the level achieved by the best performing unit 
for each pollutant).
    Relating to the Sierra Club's claim that EPA erred in considering 
the emissions of units other than the best controlled unit, the Court 
refused to rule that EPA's approach was unlawful, and posited that 
``[p]erhaps considering all units with the same technology is 
justifiable because the best way to predict the worst reasonably 
foreseeable performance of the best unit with the available data is to 
look at other units' performance. Or perhaps EPA reasonably considered 
all units with the same technology equally `well-controlled,' so that 
each unit with the best technology is a `best-controlled unit' even if 
such units vary widely in performance.'' Sierra Club v. EPA, 167 F.3d 
at 665.
    However, the Court concluded that the possible rationale for this 
treatment of new units was not presented in the rulemaking record with 
enough clarity for the Court to determine that EPA's ``path may 
reasonably be discerned.'' Id. Moreover, the Court ruled that EPA had 
``not explained why the phrase best controlled similar unit encompasses 
all units using the same technology as the unit with the best observed 
performance, rather than just that unit itself[. * * * W]e do not know 
what interpretation the agency chose, and thus cannot evaluate its 
choice.'' Sierra Club v. EPA, 167 F.3d at 665. The Court further 
directed EPA to provide additional explanation regarding how the Agency 
had calculated the upper bound of the best-controlled unit's 
performance through rounding. Id.
    b. The Court's Ruling on Existing Units. With respect to existing 
units, the Court first rejected the Sierra Club's ``claim that EPA's 
decision to base the floors on regulatory data fails the first step of 
the Chevron test. None of the Sierra Club's arguments establish that 
Congress has `directly addressed' and rejected the use of regulatory 
data.'' Id., at 661. After noting that the Sierra Club's statutory 
objections to EPA's methodology appeared to be premised on ``the 
counterintuitive proposition that an `achieved' level may not be 
`achievable,' or, as Sierra Club puts it, may be better than `EPA's 
notions about what is achievable,' '' id. at 662, the Court rejected 
the Sierra Club's statutory objections to using regulatory data and 
uncontrolled (i.e., combustion-controlled) emissions values. In other 
words, the Court implicitly embraced EPA's view, under the principle of 
National Lime, that the MACT floor is premised on the fundamental 
concept that it be ``achievable,'' and should not be set at a level 
that happens to be reflected by the lowest observed data point without 
consideration of variability in operating conditions. Then, after 
analyzing and rejecting the Sierra Club's arguments that the plain 
language of the CAA and its legislative history forbid EPA's 
methodology, the Court further ruled that it found ``nothing inherently 
impermissible about construing the statute to permit the use of 
regulatory data--if they allow EPA to make a reasonable estimate of the 
performance of the top 12 percent of units. Indeed, the Sierra Club 
conceded at oral argument that `a reasonable sample' may be used `to 
find out what the best 12 percent are doing.' Oral Arg. Tr. at 11. To 
be sure, the Sierra Club did not concede that permit data may be used. 
But neither has it provided any basis for believing that state and 
local limitations are such weak indicators of performance that using 
them is necessarily an impossible stretch of the statutory terms. [* * 
*] We therefore reject the Sierra Club's argument that the CAA forbids 
the use of permit and regulatory data, and hold that the use of such 
information is permissible as long as it allows a reasonable inference 
as to the performance of the top 12 percent of units. Similarly, as 
long as there is a reasonable basis for believing that some of the best 
performing 12 percent of units are uncontrolled [i.e., combustion 
controlled], EPA may include data points giving a reasonable 
representation of the performance of those units in its averaging.'' 
Sierra Club v. EPA, 167 F.3d at 662, 663. Thus, the Court rejected all 
of the Sierra Club's

[[Page 5517]]

arguments that the CAA prohibits EPA from basing MACT floor 
determinations on permit or regulatory data, or on uncontrolled (i.e., 
combustion-controlled) emissions values.
    However, in addressing the manner in which EPA had specifically 
relied upon such data in the HMIWI rulemaking, the Court concluded that 
``[a]lthough EPA said that it believed the combination of regulatory 
and uncontrolled [i.e., combustion-controlled] data gave an accurate 
picture of the relevant [HMIWI]s` performance, it never adequately said 
why it believes this. [* * *] First, EPA has said nothing about the 
possibility that [HMIWI]s might be substantially overachieving the 
permit limits. If this were the case, the permit limits would be of 
little value in estimating the top 12 percent of [HMIWI]s' performance. 
[* * *] Second, EPA never gave any reason for its apparent belief that 
[HMIWI]s that were not subject to permit requirements did not deploy 
emission controls of any sort. Unless there is some finding to this 
effect, it is difficult to see the rationality in using `uncontrolled' 
[i.e., combustion-controlled] data for the units that were not subject 
to regulatory requirements.'' Id., at 663-664. The Court further 
questioned the rationality of EPA using the highest of its test run 
data in cases where the regulatory data did not alone comprise the 
necessary 12 percent. Id., at 664.
    c. Subsequent Court Rulings Relevant to the Remand. Following the 
Court's remand of the HMIWI MACT floors in Sierra Club v. EPA, the 
Court issued a series of rulings in other cases addressing MACT rules 
that bear on EPA's proposed response regarding HMIWI. The first of 
these was Nat'l Lime Ass'n v. EPA, 233 F.3d 625 (D.C. Cir. 2000) (``NLA 
II''), which involved challenges to EPA's MACT standards under CAA 
section 112(d) for portland cement manufacturing facilities. In that 
case, the Sierra Club argued that EPA should have based its estimate of 
the top performing 12 percent of sources on actual emissions data, in 
order to ``reasonably estimate'' such performance. But the Court 
determined that EPA's approach of selecting ``the median [performing] 
plant out of the best twelve percent of the plants for which it had 
information and set[ting] the * * * floor at the level of the worst 
performing plant in its databases using th[e same] technology [as the 
median plant]'' had not been shown by the Sierra Club to reflect a not 
reasonable estimate. NLA II, 233 F.3d at 633.
    In addition, the Court partially clarified its position regarding 
EPA's approach of accounting for emissions performance variability by 
setting floors at a level that reasonably estimates ``the performance 
of the `best controlled similar unit' under the worst reasonably 
foreseeable circumstances.'' Sierra Club, 167 F.3d at 665. In NLA II, 
the Court stressed that EPA should not simply set floors at levels 
reflecting the worst foreseeable circumstances faced by any worst 
performing unit in a given source category, and that while considering 
all units with the same technology may be justifiable because the best 
way to predict the worst reasonably foreseeable performance of the best 
unit with available data is to look at other units' performance, such 
an approach would satisfy the CAA ``if pollution control technology 
were the only factor determining emission levels of that HAP.'' NLA II, 
233 F.3d at 633.
    In Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 (D.C. Cir. 
2001) (``CKRC''), the Court again refined its view on when it is 
appropriate for EPA to base MACT floors on the performance of air 
pollution control technology. In that case, the Sierra Club challenged 
EPA's MACT standards for hazardous waste combustors (HWC), and argued 
that factors other than MACT technology influenced the emissions 
performance of the best performing sources.
    The Court agreed that since EPA's record evidence in the HWC 
rulemaking showed that factors besides MACT controls significantly 
influenced HWC emission rates, ''emissions of the worst-performing MACT 
source may not reflect what the best-performers actually achieve.'' 
CKRC, 255 F.3d at 864. EPA had claimed that MACT floors must be 
achievable by all sources using MACT technology, and that to account 
for the best-performing sources'' operational variability we had to 
base floors on the worst performers'' emissions. But the Court stressed 
that ``whether variability in the MACT control accurately estimates 
variability associated with the best performing sources depends on 
whether factors other than MACT control contribute to emissions[,]'' 
id., and that ``the relevant question here is not whether control 
technologies experience variability at all, but whether the variability 
experienced by the best-performing sources can be estimated by relying 
on emissions data from the worst-performing sources using the MACT 
control.'' Id., at 865.
    In the specific case of the HWC rule, the Court concluded that, 
since record evidence showed that non-MACT factors influenced emissions 
performance, EPA could not base floors simply on the worst-performing 
MACT sources' emissions. Id., at 866. However, the Court also 
reiterated that ``[i]f in the case of a particular source category or 
HAP, the Agency can demonstrate with substantial evidence--not mere 
assertions--that MACT technology significantly controls emissions, or 
that factors other than the control have a negligible effect, the MACT 
approach could be a reasonable means of satisfying the statute's 
requirements.'' Id.
5. Are revisions to the emission limits being proposed in response to 
the remand?
    Yes, the proposed response to the remand would revise some of the 
emission limits in both the NSPS and emission guidelines. Relative to 
the NSPS, the emission limits for CO, Pb, Cd, Hg, PM, and CDD/CDF would 
be revised. Relative to the emission guidelines, the emission limits 
for HCl, Pb, Cd, and CDD/CDF would be revised. EPA believes that the 
revised emission limits being proposed as a result of its response to 
the remand can be achieved with the same emission control technology 
currently used by HMIWI. The proposed emission limits for the NSPS and 
emission guidelines necessary to respond to the Court's remand are 
summarized in Table 3 of this preamble. Note that in several cases, 
further amendments to the emission limits are being proposed as a 
result of our 5-year review under CAA section 129(a)(5). Those proposed 
amendments are discussed in the following section of this preamble.

                     Table 3.--Summary of Proposed Emission Limits in Response to the Remand
----------------------------------------------------------------------------------------------------------------
                                                          Proposed remand
       Pollutant  (units)             Unit size \1\          limit for       Proposed remand limit for new HMIWI
                                                        existing HMIWI \2\                   \2\
----------------------------------------------------------------------------------------------------------------
HCl (ppmv)......................  L, M, S.............  78 or 93%           15\3\ or 99% reduction \3\.
                                                         reduction \3\.
                                  SR..................  3,100 \3\.........  N/A \4\.
CO (ppmv).......................  L, M, S.............  40 \3\............  32
                                  SR..................  40 \3\............  N/A \4\.

[[Page 5518]]

Pb (mg/dscm)....................  L, M................  0.78 or 71%         0.060 or 98% reduction \3\.
                                                         reduction.
                                  S...................  0.78 or 71%         0.78 or 71% reduction.
                                                         reduction.
                                  SR..................  8.9...............  N/A \4\.
Cd (mg/dscm)....................  L, M................  0.11 or 66%         0.030 or 93% reduction.
                                                         reduction \3\.
                                  S...................  0.11 or 66%         0.11 or 66% reduction \3\.
                                                         reduction \3\.
                                  SR..................  4 \3\.............  N/A \4\.
Hg (mg/dscm)....................  L, M................  0.55 \3\ or 87%     0.45 or 87% reduction.
                                                         reduction.
                                  S...................  0.55 \3\ or 87%     0.47 or 87% reduction.
                                                         reduction.
                                  SR..................  6.6...............  N/A \4\.
PM (gr/dscf)....................  L...................  0.015 \3\.........  0.009
                                  M...................  0.030 \3\.........  0.009
                                  S...................  0.050 \3\.........  0.018
                                  SR..................  0.086 \3\.........  N/A \4\.
CDD/CDF, total (ng/dscm)........  L, M................  115...............  20
                                  S...................  115...............  111
                                  SR..................  800 \3\...........  N/A \4\.
CDD/CDF, TEQ (ng/dscm)..........  L, M................  2.2...............  0.53
                                  S...................  2.2...............  2.1
                                  SR..................  15 \3\............  N/A \4\.
NOX (ppmv)......................  L, M, S.............  250 \3\...........  225
                                  SR..................  250 \3\...........  N/A \4\
SO2 (ppmv)......................  L, M, S.............  55 \3\............  46
                                  SR..................  55 \3\............  N/A \4\.
----------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small; SR = Small Rural
\2\ All emission limits are measured at 7 percent oxygen.
\3\ No change proposed.
\4\ Not applicable.

B. Proposed Amendments (CAA Section 129(a)(5) 5-Year Review)

    Section 129(a)(5) of the CAA requires EPA to conduct a review of 
the NSPS and emissions guidelines at 5 year intervals and, if 
appropriate, revise the NSPS and emission guidelines pursuant to the 
requirements under sections 111 and 129 of the CAA. In conducting such 
reviews, EPA attempts to assess the performance of and variability 
associated with the installed emissions control equipment (and 
developments in practices, processes and control technologies) and to 
revise as necessary and appropriate the NSPS and emission guidelines. 
In these reviews, EPA takes into account the currently installed 
equipment and its performance and operational variability. As 
appropriate, we also consider new technologies that have been 
demonstrated to reliably control emissions from the source category. In 
setting numerical emission limits from single, ``snap shot'' stack test 
data, EPA must exercise technical judgment to ensure the achievability 
of such limits over the course of anticipated operating conditions. EPA 
has completed the 5-year review, and the proposed amendments discussed 
below reflect the changes that EPA has determined are appropriate in 
addition to the amendments that are necessary to respond to the Court's 
remand. These proposed amendments do not reflect adoption of new 
control technologies or processes, but do reflect more efficient 
practices in operation of the control technologies that sources used in 
order to meet the 1997 MACT standards.
    Following year 2002 compliance with the emission guidelines, EPA 
gathered information on the performance levels actually being achieved 
by HMIWI that were operating under the guidelines. After implementation 
of the guidelines in 1997, approximately 94 percent of HMIWI shut down, 
and 3 percent demonstrated eligibility for exemptions from the HMIWI 
regulation. Those HMIWI that remained in operation either continued 
operation with their existing configuration or were retrofitted with 
add-on air pollution control devices in order to meet the standards. 
The retrofits were completed on time, and the controls installed to 
meet the required emission limitations were highly effective in 
reducing emissions of all of the CAA section 129 pollutants emitted by 
HMIWI. For those HMIWI, relative to a 1995 baseline, the emission 
guidelines reduced organic emissions (CDD/CDF) by about 90 percent, 
metals emissions (Pb, Cd, and Hg) by more than 80 percent, and acid gas 
emissions (HCl and SO2) by more than 70 percent. Including 
shutdowns and exemptions, nationwide HMIWI emissions of organics, 
metals, and acid gases each decreased by about 99 percent or more 
relative to a 1995 baseline. It should be noted that the original HMIWI 
emission limits were based primarily on permit information and other 
regulatory requirements, and not on actual performance or stack test 
data. To this end, it was highly uncertain at promulgation what the 
precise performance efficiency and day-to-day operational variability 
associated with the promulgated regulatory requirements would yield. 
Thus, the 2002 compliance test information provided the first 
quantitative assessment of the performance of the installed control 
equipment's ability to attain the NSPS and emissions guideline limits.
    The goal of the current technology review is to assess the 
performance efficiency of the installed equipment and to ensure that 
the emission limits reflect the performance of the technologies 
required by the MACT standards. In addition, the review addresses 
whether new technologies and processes and improvements in practices 
have been demonstrated at sources subject to the emissions limitations. 
EPA's intent for future technology reviews is to include similar 
analyses that also assess risk along with new technologies. For the 
current review, while new technologies have not yet been demonstrated 
to reliably control emissions more efficiently at reasonable cost at 
HMIWI units than those used to meet MACT, improvements in operational 
practices

[[Page 5519]]

do support some additional revision of the standards, in order to 
better reflect the best operation of the MACT controls.
    These proposed amendments would revise the NSPS and emission 
guidelines, in some cases beyond the point needed to respond to the 
Court's remand, based on the performance levels currently being 
achieved by HMIWI. The revisions discussed in the following text apply 
to both the NSPS and the emission guidelines, unless otherwise 
specified.
1. Are revisions to the emission limits being proposed?
    Yes, the proposed amendments would revise the emission limits in 
both the NSPS and emission guidelines. EPA's technology review 
demonstrates that the proposed emission limits can be achieved with the 
same emission control technology currently used by HMIWI. The proposed 
emission limits for the NSPS and emission guidelines are summarized in 
Tables 4 and 5 of this preamble.

                    Table 4.--Summary of Proposed 5-Year Review Emission Limits for New HMIWI
----------------------------------------------------------------------------------------------------------------
          Pollutant (units)                    Unit Size \1\                      Proposed Limit \2\
----------------------------------------------------------------------------------------------------------------
HCl (ppmv)...........................  L, M, S......................  15 \3\ or 99% reduction \3\.
CO (ppmv)............................  L, M, S......................  25
Pb (mg/dscm).........................  L, M.........................  0.060 or 99% reduction.
                                       S............................  0.64 or 71% reduction.
Cd (mg/dscm).........................  L, M.........................  0.0050 or 99% reduction.
                                       S............................  0.060 or 74% reduction.
Hg (mg/dscm).........................  L, M.........................  0.19 or 96% reduction.
                                       S............................  0.33 or 96% reduction.
PM (gr/dscf).........................  L, M.........................  0.0090.
                                       S............................  0.018.
CDD/CDF, total (ng/dscm).............  L, M.........................  16
                                       S............................  111
CDD/CDF, TEQ (ng/dscm)...............  L, M.........................  0.21
                                       S............................  2.0
NOX (ppmv)...........................  L, M, S......................  212
SO2 (ppmv)...........................  L, M.........................  21
                                       S............................  28
----------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small
\2\ All emission limits are measured at 7 percent oxygen.
\3\ No change proposed.

                 Table 5.--Summary of Proposed 5-Year Review Emission Limits for Existing HMIWI
----------------------------------------------------------------------------------------------------------------
          Pollutant (units)                    Unit Size \1\                      Proposed Limit \2\
----------------------------------------------------------------------------------------------------------------
HCl (ppm)............................  L, M, S......................  51 or 94% reduction.
                                       SR...........................  398
CO (ppm).............................  All..........................  25
Pb (mg/dscm).........................  L, M, S......................  0.64 or 71% reduction.
                                       SR...........................  0.60
Cd (mg/dscm).........................  L, M, S......................  0.060 or 74% reduction.
                                       SR...........................  0.050
Hg (mg/dscm).........................  L, M, S......................  0.33 or 96% reduction.
                                       SR...........................  0.25\3\
PM (gr/dscf).........................  L............................  0.015
                                       M............................  0.030 \3\
                                       S............................  0.030
                                       SR...........................  0.030
CDD/CDF, total (ng/dscm).............  L, M, S......................  115
                                       SR...........................  800 \3\
CDD/CDF, TEQ (ng/dscm)...............  L, M, S......................  2.0
                                       SR...........................  15 \3\
NOX (ppmv)...........................  All..........................  212
SO2 (ppmv)...........................  All..........................  28
----------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small; SR = Small Rural
\2\ All emission limits are measured at 7 percent oxygen.
\3\ No change proposed.

    As indicated by Table 5 of this preamble, the proposed emission 
limits for Pb, Cd, and Hg for existing small rural HMIWI are more 
stringent than those being proposed for existing large, medium, and 
small HMIWI. We believe that this better emissions performance by 
existing small rural HMIWI is a result of the waste stream of a small 
rural hospital not including certain materials that are in the waste 
stream of a non-rural hospital and that cause relatively higher Pb, Cd 
and Hg emissions.
2. Are other amendments being proposed?
    The proposed amendments would also make the following changes based 
on information received during implementation of the HMIWI NSPS and 
emission guidelines and would

[[Page 5520]]

apply equally to the NSPS and emission guidelines, unless otherwise 
specified.
    a. Performance Testing and Monitoring Amendments. The proposed 
amendments would allow sources to use the results of previous emissions 
tests to demonstrate compliance with the revised emission limits as 
long as the sources certify that the previous test results are 
representative of current operations. Only those sources whose previous 
emissions tests do not demonstrate compliance with one or more revised 
emission limits would be required to conduct another emissions test for 
those pollutants (note that sources are already required to test for 
HCl, CO, and PM on an annual basis). The proposed amendments would 
require, for existing HMIWI, annual inspections of scrubbers and fabric 
filters, and a one-time Method 22 visible emissions test of the ash 
handling operations to be conducted during the next compliance test. 
For new HMIWI, the proposed amendments would require CO continuous 
emissions monitoring systems (CEMS), bag leak detection systems for 
fabric-filter controlled units, annual inspections of scrubbers and 
fabric filters, and Method 22 visible emissions testing of the ash 
handling operations to be conducted during each compliance test. For 
existing HMIWI, use of CO CEMS would be an approved alternative, and 
specific language with requirements for CO CEMS is included in the 
proposed amendments. For new and existing HMIWI, use of PM, HCl, multi-
metals, and Hg CEMS, and semi-continuous dioxin monitoring (continuous 
sampling with periodic sample analysis) also are approved alternatives, 
and specific language for these alternatives is included in the 
proposed amendments.
    b. Other Amendments. The proposed amendments would revise the 
definition of ``Minimum secondary chamber temperature'' to read 
``Minimum secondary chamber temperature means 90 percent of the highest 
3-hour average secondary chamber temperature (taken, at a minimum, once 
every minute) measured during the most recent performance test 
demonstrating compliance with the PM, CO, and dioxin/furan emission 
limits.''
    The proposed amendments would require sources to submit, along with 
each test report, a description of how operating parameters are 
established during the initial performance test and subsequent 
performance tests.
3. Is an implementation schedule being proposed?
    Yes; under the proposed amendments to the emission guidelines, and 
consistent with CAA section 129, revised State plans containing the 
revised emission limits and other requirements in the proposed 
amendments would be due within 1 year after promulgation of the 
amendments. That is, revised State plans would have to be submitted to 
EPA 1 year after the date on which EPA promulgates revised standards.
    The proposed amendments to the emission guidelines then would allow 
HMIWI units up to 3 years from the date of approval of a State plan, 
but not later than 5 years after promulgation of the revised standards, 
to demonstrate compliance with the amended standards. Consistent with 
CAA section 129, EPA expects States to require compliance as 
expeditiously as practicable. HMIWI units have already installed the 
emission control equipment necessary to meet the proposed revised 
limits, and EPA, therefore, anticipates that most State plans will 
include compliance dates sooner than 5 years following promulgation of 
the amendments. In most cases, the only changes necessary are to review 
the revisions and adjust the emission monitoring and reporting 
accordingly.
    In revising the emission limits in a State plan, a State has two 
options. First, it could include both the current and the new emission 
limits in its revised State plan, which allows a phased approach in 
applying the new limits. That is, the State plan would make it clear 
that the current emission limits remain in force and apply until the 
date the new emission limits are effective (as defined in the State 
plan). States whose HMIWI units do not find it necessary to improve 
their performance in order to meet the new emission limits may want to 
consider a second approach where the State would insert the new 
emission limits in place of the current emission limits, follow 
procedures in 40 CFR part 60, subpart B, and submit a revised State 
plan to EPA for approval. If the revised State plan contains only the 
new emission limits (i.e., the current emission limits are not 
retained), then the new emission limits must become effective 
immediately since the current limits would be removed from the State 
plan.
4. Has EPA changed the applicability date of the 1997 NSPS?
    No; however, HMIWI may be treated differently under the amended 
standards than they were under the 1997 standards in terms of whether 
they are ``existing'' or ``new'' sources, and there will be new dates 
defining what are ``new'' sources and imposing compliance deadlines 
regarding any amended standards. The applicability date for the NSPS 
units, with respect to the standards as promulgated in 1997, remains 
June 20, 1996; however, units for which construction is commenced after 
the date of this proposal, or modification is commenced on or after the 
date 6 months after promulgation of the amended standards, would be 
subject to more stringent NSPS emission limits than units for which 
construction or modification was completed prior to those dates. Under 
the proposed amendments, units that commenced construction after June 
20, 1996, and on or before February 6, 2007, or that are modified 
before the date 6 months after the date of promulgation of any revised 
final standards, would continue to be or would become subject to the 
NSPS emission limits that were promulgated in 1997 and that remain in 
the 40 CFR part 60, subpart Ec NSPS, except where the revised emission 
guidelines would be more stringent. In that case, HMIWI that are NSPS 
units under the 1997 rule would also need to comply with the revised 
emission guidelines for existing sources, by the applicable compliance 
date for such existing sources. Similarly, emission guidelines units 
under the 1997 rule would need to meet the revised emission guidelines 
by the applicable compliance date for the revised guidelines. HMIWI 
that commence construction after February 6, 2007 or that are modified 
6 months or more after the date of promulgation of any revised 
standards would have to meet the revised NSPS emission limits being 
added to the subpart Ec NSPS and any remaining NSPS limits from the 
1997 rule, as applicable, within 6 months after the promulgation date 
of the amendments or upon startup, whichever is later.

IV. Rationale

A. Rationale for the Proposed Response to the Remand

    This action responds to the Court's remand by (1) further 
explaining the reasoning processes by which EPA determined the MACT 
floors and the MACT standards for new and existing HMIWI for the 
portions of those processes that are being retained under our remand 
response, and (2) explaining revisions to the processes, the MACT 
floors, and the MACT standards for new and existing HMIWI that result 
from our response to the remand.
1. New HMIWI
    The Court raised three issues with regard to EPA's treatment of the 
MACT floor for new units and the achievable

[[Page 5521]]

emission limitations. First, the Court asked EPA to explain why the 
floor was based on the highest emissions levels of the ``worst-
performing'' unit employing the MACT technology rather than on the 
lowest observed emissions levels of the best performing unit using the 
MACT technology. (See Sierra Club v. EPA, 167 F.3d at 665.) Second, the 
Court requested further explanation of why EPA considered multiple 
units employing the MACT technology, rather than identify the single 
best-performing unit and basing the floor on that particular unit's 
performance with that technology. Id. Third, the Court requested 
further explanation of EPA's procedure for determining the achievable 
emission limitation from the available data, where EPA selected a 
numerical value somewhat higher than the highest observed data point. 
The Court stated that EPA's procedure ``[m]ay be justifiable as a means 
of reasonably estimating the upper bound of the best-controlled unit's 
performance, but in the absence of agency explanation of both the 
decision to increase the levels and the choice of method for 
determining the increases, we are in no position to decide.'' Id.
    As discussed in detail below, for the first two issues, the Court 
described potential rationale for EPA's method. However, because the 
Court concluded that this rationale was not adequately presented in the 
rulemaking record, the Court asked for further clarification by EPA. In 
subsequent cases the Court further addressed these potential 
rationales, and discussed under what circumstances they would and would 
not be persuasive. In fact, the Court's potential rationale for EPA's 
method reflects the principles used by EPA in determining the MACT 
floor for new units and the achievable emission limitations for this 
source category, and is the method that has been used by EPA throughout 
most of the Agency's 30-year history in developing achievable 
technology-based emission limitations for source categories in cases 
where the application of control technology has been the only means by 
which sources have limited emissions, and the variability of technology 
performance is a critical factor in determining an emission 
limitation's achievability. (See, e.g., American Iron and Steel Inst. 
v. EPA, 115 F.3d 979, 1000 (D.C. Cir. 1997); BP Exploration & Oil, 
Inc., v. EPA, 66 F.3d. 784, 794 (6th Cir. 1995); NRDC v. EPA, 790 F.2d 
289, 299 (3d Cir. 1986); National Ass'n of Metal Finishers v. EPA, 719 
F.2d 624, 659 (3d Cir. 1983); rev'd on other grounds sub nom, Chemical 
Mfrs. Ass'n v. NRDC, 470 U.S. 116 (1985); American Petroleum Inst. v. 
EPA, 661 F.2d 340, 347 n. 23 (5th Cir. 1981); Bunker Hill Co. v. EPA, 
572 F.2d 1286, 1302 (9th Cir. 1977); Marathon Oil Co. v. EPA, 564 F.2d 
1253, 1266-67 (9th Cir. 1977); FMC v. Train, 639 F.2d 973, 985-86 (4th 
Cir. 1976).) As discussed elsewhere in this preamble, in CKRC the Court 
stressed that where record evidence suggests that factors other than 
application of control technology influence emissions, EPA will not be 
able to demonstrate ``that floors based on the worst-performing MACT 
sources' emissions represent `a reasonable estimate of the performance 
of the [best-performing] units.' '' CKRC, 255 F.3d at 866, quoting 
Sierra Club, 167 F.3d at 662. However, the Court reiterated that where 
EPA's record demonstrates that MACT technology significantly controls 
emissions, or that factors other than the control have a negligible 
effect, the approach of accounting for variability by basing the floor 
on the highest emissions resulting from a source using MACT technology 
``could be a reasonable means of satisfying the statute's 
requirements.'' CKRC, at 866.
    a. Applicability of National Lime to CAA Section 129. CAA section 
129(a)(3) states that ``[s]tandards under section 111 and this section 
applicable to solid waste incineration units shall be based on methods 
and technologies for removal or destruction of pollutants before, 
during, or after combustion [* * *].'' This language requires that such 
a standard be based on the degree of reduction in air pollutant 
emissions that can be achieved through application of a particular 
method of pollution control, and any other factors that record evidence 
shows significantly affect emissions performance. Much like the 
language in CAA sections 111 and 129 governing the HMIWI standards, 
Congress has used similar language in other statutes to direct adoption 
of technology-based standards. (See, e.g., CAA section 169(3) defining 
``best available control technology''; Clean Water Act section 
301(b)(2)(A), for ``best available technology economically achievable'' 
or ``BAT'' standards; Clean Water Act section 304(b)(1) for ``best 
practicable technology'' or ``BPT'' standards.)
    As the Court has stated, ``[t]echnology-based provisions [in the 
CAA] require EPA to promulgate standards only after finding that the 
requisite technology exists or may be feasibly developed. Absolute 
standards, on the other hand, require compliance with statutorily 
prescribed standards and time tables, irrespective of present 
technologies.'' (See NRDC v. Reilly, 983 F.2d 259, 268 (D.C. Cir. 1993) 
(holding that elimination of feasibility requirements and specification 
of particular control systems indicated that congressional amendment of 
CAA section 202(a)(6) resulted in an ``absolute'' standard).) MACT 
standards under CAA sections 111 and 129 are ``technology-based,'' 
rather than ``absolute'' standards. The legislative history to the 1990 
CAA Amendments clearly shows that Congress intended the MACT standards 
to be technology-based. (See I A Legislative History, at 863 (Senator 
Durenberger referring to ``the MACT technology-based standards'' in 
debates on the bill reported by the Conference Committee); id., at 1128 
(Senator Dole explaining that changes made to CAA section 129 in the 
Conference Committee ``make the technology test more closely 
approximate the role of the NSPS''); S. Rep. No. 101-228, at 133-134 
(1989) (referring to CAA section 112 MACT standards as ``technology-
based standards'' and noting that technology-based effluent standards 
under the Clean Water Act served as a model for the new MACT 
standards).)
    CAA section 129 does not specify a type of control technology for 
HMIWI, but instead requires EPA to develop floor levels already 
achieved in practice by one or more units, and then issue standards 
that EPA determines are ``achievable'' for units in that source 
category. As the Court stated in National Lime Ass'n v. EPA (627 F.2d 
416, 431 n. 46 (D.C. Cir. 1980)) (``NLA I''), and restated in Sierra 
Club, ``where a statute requires a standard to be achievable, it must 
be achievable `under most adverse circumstances which can reasonably be 
expected to recur.' '' (See Sierra Club, 167 F.3d at 665.) In other 
words, ``EPA would be justified in setting floors at a level that is a 
reasonable estimate of the performance of the `best controlled similar 
unit'' under the worst reasonably foreseeable circumstances[.]'' Id. 
This concept of ``worst reasonably foreseeable circumstances'' is 
fundamental in developing achievable technology-based emission 
limitations, since, once the standard is in force, sources will be 
expected to comply with it at all times by relying on the technology 
that formed the basis for EPA's determination that the promulgated 
emissions limitation is achievable. As the Court stated in Sierra Club, 
`[i]t is reasonable to suppose that if an emissions standard is as 
stringent as `the emissions control that is achieved in practice' by a 
particular unit, then that particular unit will not violate the 
standard. This only results if `achieved in practice' is interpreted to

[[Page 5522]]

mean `achieved under the worst foreseeable circumstances.' '' Id.
    EPA agrees with the Court that, in order to satisfy the 
requirements of NLA I, ``[t]he same principle should apply when a 
standard is to be derived from the operating characteristics of a 
particular unit[,]'' as is the case under CAA section 129(a)(2). Id. 
CAA section 129(a)(2) requires that the new unit MACT floor be ``not 
less stringent than the emissions control that is achieved in practice 
by the best controlled similar unit, as determined by the 
Administrator.'' It would have been unreasonable for EPA to base the 
MACT floors solely on the lowest levels of emissions observed without 
an assessment of whether those observed levels could be met on a 
continuous basis, and the CAA and its legislative history provide no 
support in deviating from the general practice EPA has followed in the 
wake of NLA I. In a report on H.R. 3030, the House Committee on Energy 
and Commerce explained that ``MACT is not intended to require unsafe 
control measures, or to drive sources to the brink of shutdown.'' (See 
H.R. Rep. No. 101-490, pt. 1, at 328 (1990).) This view is consistent 
with NLA I, which involved challenges to standards EPA promulgated 
under section 111 of the CAA and is particularly applicable to the 
HMIWI rulemaking under CAA section 129, since this rule has its basis 
in authority in both section 129 and section 111. (See CAA section 
129(a)(1)(A) and (C).)
    Moreover, interpreting CAA section 129 as subject to the principles 
of NLA I appropriately notes the critical distinction between a level 
of emissions that has been continuously achieved through performance 
using control technology, and one that has been observed at a single 
point in time. A level that has been continuously achieved is capable 
of being met under most conditions which can reasonably be expected to 
recur because variability in operating conditions is taken into 
account. Such a level best effectuates Congress' intent because it 
ensures that the MACT floor will result in reduced emissions without 
forcing sources to shut down. A lowest observed emission level, 
however, is not representative of a unit's performance under most 
conditions which can reasonably be expected, and may be impossible to 
achieve on a regular, let alone continuous, basis. While an observed 
lowest emissions level may be appropriate for use in determining 
whether a source is in compliance with an emission standard that must 
be continuously met, it is not an appropriate level upon which to base 
the minimum stringency level of such a standard.
    In addition, Congress' use of the phrases ``as determined by the 
Administrator'' and ``achieved in practice'' in CAA section 129(a)(2) 
in the directive to establish MACT floors shows that Congress expected 
EPA to consider variability in operating conditions and other relevant 
factors in the Agency's determinations. The term ``practice'' is 
defined as ``[r]epeated or customary action; habitual performance; a 
succession of acts of a similar kind; custom; usage.'' (See Black's Law 
Dictionary 1172 (6th ed. 1990).) Thus, achieved in ``practice'' means 
achieved on a repeated, customary, or habitual basis. Under the 
statutory mandate that the level ``achieved in practice'' be 
``determined by the Administrator,'' EPA must exercise its judgment, 
based on an evaluation of the relevant factors and available data, to 
determine the level of emissions control that can be customarily 
achieved using the relied-upon technology under variable conditions. 
Merely locating the lowest emissions data point and setting the MACT 
standard at that level would not constitute a considered 
``determination by the Administrator'' as to what has been ``achieved 
in practice.'' (See, e.g., Senate Debate on Conference Report, 10-26-
90, reprinted in I A Legislative History of CAA Amendments of 1990, 
103d Cong., 1st Sess. at 1128-1129 (Comm. Print 1993) (exchange between 
Senators Dole and Durenberger confirming that the phrase ``achieved in 
practice'' accounts for the distinction between research-type pollution 
control systems and systems that are ``economically viable for 
widespread use,'' and stressing that MACT floors should rely upon 
technologies that can ``stand the rigors of day to day operations'').)
    Ultimately, NLA I is controlling because the case addressed how 
standards must be set in the face of variable operating conditions, and 
involved one of the same provisions of the CAA, section 111, under 
which the HMIWI rule was promulgated. NLA I held that EPA is required 
to use data that is representative of emissions that could be achieved 
in the industry as a whole. (See 627 F.2d at 433.) In developing the 
standards at issue in that case, EPA relied upon tests of the emissions 
from particular units to determine the level of emissions control that 
was achievable across the entire industry. The Court directed EPA to 
identify ``variable conditions that may contribute substantially to the 
amount of emissions, or otherwise affect the efficiency of the 
emissions control systems.'' Id. The Court then stated that ``where 
test results are relied upon, it should involve the selection or use of 
test results in a manner which provides some assurance of the 
achievability of the standard for the industry as a whole, given the 
range of variable factors found relevant to the standards' 
achievability.'' Id. This does not mean that EPA must test every plant, 
but it does mean that ``due consideration must be given to the possible 
impact on emissions of recognized variations in operations and some 
rationale offered for the achievability of the promulgated standards 
given the tests conducted and the relevant variables identified.'' Id., 
at 434. Thus, applying NLA I to the HMIWI rule adopted under CAA 
sections 111 and 129, it is really a misnomer to characterize EPA as 
basing the MACT floor on the emissions of the ``worst performing'' unit 
using the technology in question, since that unit's level of emissions 
necessarily more closely represents the level ``achieved in practice'' 
by the given technology than would the lowest emissions level observed 
at a source using that ``best'' technology.
    b. Variability Between Facilities or Units. In remanding the NSPS 
at issue in NLA I, the Court noted that its decisions under CAA section 
111 ``evince a concern that variables be accounted for, that the 
representativeness of test conditions be [sic] ascertained, that the 
validity of tests be assured and the statistical significance of 
results be determined.'' (See NLA I, 627 F.2d at 452-53.) (See, also, 
Portland Cement Ass'n v. Ruckelshaus, 486 F.2d 375, 396 (D.C. Cir. 
1973), cert. denied, 417 U.S. 921 (1974).) When floors and standards 
are developed based on emissions data, EPA accounts for several types 
of variability to avoid adopting unachievable standards. The first type 
of variability is that concerning operational distinctions between 
facilities or units. As the Sierra Club Court stated in reviewing the 
HMIWI rule, ``[p]erhaps considering all units with the same technology 
is justifiable because the best way to predict the worst reasonably 
foreseeable performance of the best unit with the available data is to 
look at other units' performance. Or perhaps EPA reasonably considered 
all units with the same technology equally `well-controlled,' so that 
each unit with the best technology is a `best-controlled unit' even if 
such units vary widely in performance.'' (See 167 F.3d at 665.) These 
are two ways of saying essentially the same thing, and these concepts 
have

[[Page 5523]]

been used by EPA throughout most of the Agency's history in determining 
achievable technology-based emission limitations, in cases where 
application of control technology significantly controls emissions and 
no record evidence indicates that factors other than the control have 
more than a negligible effect. Examining multiple units using the same 
technology gives the best picture of the performance capability of that 
particular technology, since it provides EPA with a more complete set 
of data by which to evaluate what levels of emissions control a 
technology can achieve as it is applied to varying sources. Such an 
analysis is necessary especially when adopting standards that all 
sources in a category will have to be able to meet by using the 
identified technology. Since MACT floors and standards are generally 
expressed as numerical emissions limits, it is necessary to account for 
this variability in order to adopt a regulation that is `achievable' by 
the industry as a whole.'' (See NLA I, 627 F.2d at 437.)
    Section 129(a)(2) of the CAA requires that EPA determine the 
emissions control achieved by the ``best controlled similar unit'' when 
establishing the MACT floors for new units. A solid waste incineration 
``unit'' is defined as ``a distinct operating unit of any facility 
which combusts any solid waste material'' (CAA section 129(g)(1)). To 
achieve the best level of pollution control, that unit will utilize a 
particular method of pollution control (and possibly use other means 
that affect its emissions performance). The emissions control achieved 
by that method (and by any additional means) is the emissions control 
achieved by the ``best controlled similar unit.'' Thus, the MACT floor 
for new units is based on the ``emissions control'' that is attained by 
the specific method of pollution control and any other means used to 
limit emissions at the best similar unit, rather than merely on the 
emissions measured at a particular unit.
    In this way, by basing the MACT floor on the capability of a 
particular method of pollution control used at ``similar'' ``best'' 
``units,'' instead of on the emissions measured at a single unit, EPA 
ensures that the floors would not only be achievable by the single best 
performing unit, but are also achievable by other units using the same 
technology and/or emissions limiting means as the best similar unit, 
and that it is reasonable to require the best similar unit and all 
future new units to meet this floor on a continuous basis. In contrast, 
identifying the ``emissions control'' of the ``best controlled similar 
unit'' as being a single data point from a single source provides 
merely a snapshot of emissions performance that may not be replicable 
by either that single source or by other sources using the same control 
technology, and, therefore, does not provide a basis for enforceably 
requiring all sources to perform to that level.
    Thus, the most reasonable way to interpret the statutory phrase 
``best controlled similar unit'' in CAA section 129 is as encompassing 
all units using the same technology and emissions limiting means as the 
single unit with the best observed performance, rather than just that 
single best performing unit itself. A contrary interpretation would 
seem to directly conflict with the Court's directive in NLA I, and is 
not compelled by the Court rulings in Sierra Club, NLA II, and CKRC. 
Applying this approach to evaluating ``best technologies'' at ``best 
controlled similar units,'' where different design characteristics are 
identified (e.g., low-efficiency versus moderate-efficiency versus 
high-efficiency wet scrubbers), the data are grouped such that each 
data set reflects the performance of an ``identical'' control device, 
providing the best indication of the true performance of each control 
device and enabling the Agency to adopt a numerical standard that can 
be met with the subject technology at all units employing this 
technology, and can be enforced. Again, where the record evidence 
indicates that the only means of control of emissions at units is 
application of control technology, and there is no record evidence 
showing that other means of emissions limitation significantly affect 
emissions performance, basing the MACT floor on this approach is fully 
consistent with the Court's rulings in the MACT cases.
    c. Variability Between and Within Tests at Facilities. Another type 
of variability that EPA accounts for in order to ensure the 
achievability of technology-based standards that rely upon application 
of pollution controls concerns operational distinctions between and 
within tests at the same unit. Regarding ``between-test variability,'' 
even where conditions appear to be the same when two or more tests are 
conducted, variations in emissions are often caused by different 
settings for emissions testing equipment and differences in sample 
handling. Varying results may also be caused by use of different field 
teams to conduct the testing, or different laboratories to analyze the 
results. All these variations are typical.
    An achievable standard needs to account for these differences 
between tests, in order for ``a uniform standard [to] be capable of 
being met under most adverse conditions which can reasonably be 
expected to recur[.]'' (See NLA I, 627 F.2d at 431, n. 46.) (See also 
Portland Cement Ass'n, 486 F.2d at 396 (noting industry point that ``a 
single test offered a weak basis'' for inferring that plants could meet 
the standards).) Without accounting for variation among different 
emissions tests, it can be determined with a significant degree of 
statistical confidence that even a single unit will not be able to meet 
the standard over a reasonable period of time, when one can expect 
adverse conditions to recur. The Courts have recognized this basic 
principle in reviewing technology-based effluent standards under the 
Clean Water Act. As the U.S. Court of Appeals for the 5th Circuit 
stressed regarding ``best practicable technology'' or ``BPT'' standards 
under section 304(b)(1) of the Clean Water Act, ``[t]he same plant 
using the same treatment method to remove the same toxic does not 
always achieve the same result. Tests conducted one day may show a 
different concentration of the same toxic than are shown by the same 
test on the next day. This variability may be due to the inherent 
inaccuracy of analytical testing, i.e., `analytical variability,' or to 
routine fluctuations in a plant's treatment performance.'' (See 
Chemical Mf'rs Ass'n v. EPA, 870 F.2d 177, 228 (5th Cir. 1989).) (See 
also American Petroleum Institute v. EPA, 540 F.2d 1023, 1035-36 (10th 
Cir. 1976) (``Even in the best treatment systems, changes occur in 
ability to treat wastes. [* * *] [V]ariability factors present[] a 
practical effort to accommodate for variations in plant operations''); 
FMC Corp. v. Train, 539 F.2d 973, 985 (4th Cir. 1976) (variability 
factors account for ``the fact that even in the best treatment systems 
changes continually occur in the treatability of wastes'').)
    The same types of differences leading to between-test variability 
also cause variations in results between various runs comprising a 
single test, or ``within-test variability.'' A single test at a unit 
usually includes at least three separate test runs. (See 40 CFR 
63.7(e)(3) (for MACT standards under section 112 of the CAA), and 40 
CFR 60.8(f) (for NSPS under CAA section 111).) (See also Portland 
Cement Ass'n, 486 F.2d at 397 (noting differences in conditions among 
several test runs).)
    d. Application of NLA I, Sierra Club, NLA II, and CKRC Principles 
in HMIWI Rulemaking. Based on the record for the 1997 rulemaking, the 
best way to determine the worst reasonably foreseeable circumstances 
for the

[[Page 5524]]

particular technologies used to control emissions at HMIWI was to first 
examine the highest data point actually observed from HMIWI equipped 
with each particular technology. If an emission value has been observed 
and there is no reason to believe it represents poor performance (i.e., 
there is nothing that can be done to prevent its recurring), it is 
likely to occur again in the future and, therefore, reflects a 
foreseeable circumstance. It is incorrect to characterize the highest 
data point as the ``worst performance'' of the best performing unit, or 
to characterize one control device's performance as ``better'' than 
another's based solely on the results of a single emission test. This 
is because such focuses relate to essentially random single data 
occurrences, rather than to estimating what a particular technology can 
be expected to continuously achieve. Rather, each data point, whether 
from one unit or from several identical units using the same 
technology, should be viewed as a snapshot of the actual performance of 
the technology in use. Along with an understanding of the factors 
affecting the performance of the technology, each of these snapshots 
gives information about the normal, and unavoidable, variation in 
emissions that would be expected to recur over time when using the 
identified technology. Conversely, when there is evidence that an 
emission data point reflects poor performance (design, operation, or 
both), such a data point should not be considered in determining the 
achievable emission limitation associated with the technology.
    Furthermore, a distinction must be made between an emission level 
that has been ``observed'' and an emission limitation that can be 
continuously ``achieved.'' The purpose of the MACT program is to compel 
sources to replicate emission reduction strategies used by the best-
performing sources. Thus, MACT floors are based on the control 
strategies used by the best-performing sources to reduce emissions, not 
based on a snapshot level of emissions from sources without regard to 
whether this level reflects application of any replicable emission 
control strategies. CAA section 129(a)(2) does not direct EPA to assess 
relative emission ``levels'' in determining MACT floors; it directs EPA 
to assess the degree of emissions ``control'' or ``reduction'' or 
``limitation'' ``achieved'' by the best-controlled or best-performing 
sources. The plain meaning of these words implies that a source is 
utilizing some method or technique to reduce emissions that is within a 
source operator's power to adopt. The reference to a ``degree of 
reduction'' supports the view that the words ``control'' and 
``limitation'' appearing in section 129(a)(2) require a source to have 
reduced emissions from uncontrolled levels through some control 
technique. See NLA II, 233 F.3d at 631-32 (rejecting position that EPA 
is required to set new source floors at the lowest recorded emission 
level for which it has data and to set existing source floors at the 
average of the lowest 12 percent or recorded emission level data 
points).
    The Court has recognized that EPA may consider variability in 
estimating the degree of emission reduction achieved by best-performing 
sources and in setting MACT floors. See Mossville Envt'l Action Now v. 
EPA, 370 F.3d 1232, 1241-42 (D.C. Cir 2004) (holding EPA may consider 
emission variability in estimating performance achieved by best-
performing sources and may set floor at level that best-performing 
source can expect to meet ``every day and under all operating 
conditions''). Since an emission limitation must be complied with at 
all times, for it to be achievable it must be set at a level that will 
not force sources to violate it when operating conditions are not ideal 
and higher emissions levels might be observed. For example, a car which 
has been observed to consume 0.02 gallons of gasoline in a one-mile 
downhill stretch of highway cannot be said to have ``achieved'' a 
minimum 50 miles per gallon fuel efficiency rate when that same car is 
later certain to consume 0.04 gallons of gasoline in a one-mile uphill 
stretch of highway (25 miles per gallon). Rather, the minimum fuel 
efficiency of the car will be that which the car can meet in adverse 
circumstances, the uphill stretch. So it is with emissions limitations, 
which cannot reasonably be set at levels which would force sources to 
operate in violation even when properly employing the control 
technology upon which the standards are based.
    The emission data used to develop the emission limitations in the 
HMIWI regulations reflect properly designed and operated air pollution 
control technology on properly designed and operated HMIWI, and 
emission data that reflected poor operation of the HMIWI unit or the 
air pollution control technology were excluded. (See Legacy Docket ID 
No. A-91-61, items II-A-111 and IV-B-14.) The incinerators selected by 
EPA for testing represented a range of incinerator designs and air 
pollution control systems in use on this source category. (See Legacy 
Docket ID No. A-91-61, item IV-B-46.) The incinerators and air 
pollution controls were inspected thoroughly, and maintenance was 
performed where necessary to ensure that the incinerators and pollution 
controls were functioning properly. (See Legacy Docket ID No. A-91-61, 
items II-A-93, II-A-94, and II-A-85.) During testing, most test runs 
were conducted under representative conditions to minimize emissions. 
(See Legacy Docket ID No. A-91-61, items II-A-111, IV-B-46, and IV-B-
47.) However, some test runs were purposely conducted under conditions 
that would represent poor operation (e.g., overcharging waste to the 
incinerator) to determine the effect of improper operation on 
emissions. (See Legacy Docket ID No. A-91-61, items II-A-111 and IV-B-
46.) These test runs demonstrated that improper operation results in 
higher emissions. (See Legacy Docket ID No. A-91-61, items II-A-111, 
IV-B-46, and II-A-81.) Of course, the test runs reflecting poor 
operation were not used in developing the achievable emission 
limitations. Id. It is important to note that such poor operation is 
precluded by the good combustion requirements and the parametric 
monitoring requirements in the 1997 final rule. In addition to data 
gathered by EPA directly, vendors of air pollution control systems 
submitted test reports to EPA. (See Legacy Docket ID No. A-91-61, items 
II-I-230 through 237, II-I-243 and 244, II-I-248, IV-B-48 and 49, IV-J-
11, IV-J-15 and 16, IV-J-20, IV-J-24, IV-J-27, IV-J-29 through 31, IV-
J-33 and 34, IV-J-39 and 40, and IV-J-47.) The test reports were 
submitted primarily by wet scrubber vendors to demonstrate to EPA that 
wet scrubbers could achieve lower emissions than EPA had concluded from 
the EPA-collected data. (EPA had conducted testing on only one wet 
scrubber system.) (See 61 FR 31742; Legacy Docket ID No. A-91-61, item 
IV-B-48.) The test reports and the data collected by EPA reflect the 
best performance of the air pollution controls that can reasonably be 
expected when continuously applied on HMIWI.
    MACT and other technology-based standards are necessarily derived 
from short-term emissions test data, but such data are not 
representative of the range of operating conditions that facilities 
face on a day-to-day basis. In statistical terms, each test produces a 
limited data sample, not a complete enumeration of the available data 
for performance of the unit over a long period of time. (See Natrella, 
Experimental Statistics, National Bureau of Standards Handbook 91, 
chapter 1 (revised ed., 1966).) EPA, therefore, often needs to adjust 
the

[[Page 5525]]

short-term data to account for these varying conditions, so facilities 
properly employing optimal controls can remain in compliance with the 
standards on a continuous basis.
    With the relatively small data sets EPA had to work with in the 
1997 HMIWI rulemaking, it is possible that EPA has not recorded the 
highest emissions levels that would occur under the worst reasonably 
foreseeable circumstances. As the Court noted, it would ``generally 
defer to an agency's decision to proceed on the basis of imperfect 
scientific information, rather than to `invest the resources to conduct 
the perfect study.' '' (See Sierra Club, 167 F.3d at 662.) ``[S]ince 
EPA had data on only one percent of about 3,000 [HMIWI], the data 
gathering costs of any non-sampling method may well have been 
daunting.'' Id., at 663. In fact, the ``perfect study'' cannot be 
conducted, regardless of the resources expended to conduct it. Every 
study ends with some uncertainty in the results. There is no 
``cookbook'' methodology for determining achievable emission 
limitations from data. In every case, but especially in cases where 
data are limited as with the 1997 HMIWI rulemaking, EPA must make 
judgments about what constitutes the worst reasonably foreseeable 
circumstance and put those judgments out for public comment. In the 
case of the HMIWI rulemaking, the ``high'' data points simply reflected 
the normal, and unavoidable, variation in emissions that would be 
expected to recur over time when properly using the best control 
technologies and strategies we determined were being used at HMIWI 
units. In fact, while the highest observed value is a ``foreseeable 
circumstance,'' it may not reflect the worst reasonably foreseeable 
circumstance. In determining the 1997 final MACT standards, EPA chose 
to account for the ``worst reasonably foreseeable circumstance'' by 
adding 10 percent to the highest observed emissions levels in the data, 
and then rounding up those figures. Upon review of this approach in 
responding to the Court's remand, we have determined that although the 
highest observed data point may not reflect the ``worst reasonably 
foreseeable circumstance,'' we do not have information to support 
accounting for the ``worst reasonably foreseeable circumstance'' by 
adding 10 percent to the highest observed emissions levels, and then 
rounding up those figures. We, therefore, propose to base revised MACT 
standards for new HMIWI units on the highest observed data points 
associated with employed control strategies.
    In the CKRC case, the Court left open the possibility that the 
approach of basing floors on the ``worst-performing MACT sources'' 
emissions represent `a reasonable estimate of the performance of the 
[best-performing] units,' '' CKRC at 866, quoting Sierra Club at 662, 
provided that ``in the case of a particular source category or HAP, the 
Agency can demonstrate with substantial evidence--not mere assertions--
that MACT technology significantly controls emissions, or that factors 
other than the control have a negligible effect[.] CKRC at 866, citing 
NLA II at 633. The Court in Sierra Club essentially already found this 
to be the situation for the HMIWI rulemaking, and it was, therefore, 
appropriate for EPA to base its MACT floor review in the 1997 rule 
strictly on the emissions reductions achieved by use of control 
technologies. The Sierra Club had claimed that EPA wrongly failed to 
require HMIWI units to undertake programs to reduce the Hg and 
chlorinated plastics in HMIWI waste streams. Sierra Club, at 666. While 
the petitioner raised this objection in its challenge to the 
promulgated standards, rather than its objection to the floor 
methodology, the Court's response to the Sierra Club's claim shows that 
in the case of the 1997 HMIWI rulemaking, EPA appropriately focused on 
the control technologies used at HMIWI units, and that, therefore, 
under the CKRC ruling it was appropriate, in this instance, to base 
floors on the highest emissions levels achieved by units employing the 
MACT technologies.
    The Court observed that ``EPA does not deny that the waste stream 
reductions the Sierra Club calls for would reduce pollution. The less 
mercury in, the less mercury out, and the less chlorinated plastic in, 
the less HCl out. But the EPA has consistently argued in its response 
to comments and here that it does not have evidence that allows 
quantification of the relevant output reduction. For mercury, the only 
quantitative evidence before EPA was that a pollution prevention 
program aimed at mercury could reduce mercury emissions from very high 
levels to typical levels. See RTC at 7-14 to 7-15. For chlorinated 
plastics, there was no quantitative evidence before the agency. See RTC 
at 7-16, 7-18. The Sierra Club does not contest the adequacy of EPA's 
data-gathering with respect to these measures.'' Id. (Note that the 
emission guidelines and NSPS require HMIWI to prepare a waste 
management plan under Sec. Sec.  60.35e and 60.55c that would segregate 
from the health care waste stream certain solid waste components 
contributing to toxic emissions from the incinerator (62 FR 48380, 
48387).)
    e. Development of the Proposed Revised Emission Limits. While we 
are proposing to respond to the Court's remand regarding new units by 
basing floors and standards on the same control technologies that 
formed the basis for the 1997 standards, in some cases it is necessary 
to adjust the emission limits in order to correct for the concerns 
regarding our 1997 methodology that the Court raised. As at 
promulgation of the 1997 rule, EPA examined the data available for 
various air pollution control technologies applied to HMIWI to 
determine the performance capabilities of the technologies; identified 
the best control technology for each air pollutant for each subcategory 
of HMIWI (i.e., MACT floor); considered control technologies more 
stringent than the MACT floor; made a determination regarding the 
achievable emissions levels from using control technologies upon which 
the emission standards would be based; and then established numerical 
emission limits achievable with those technologies. The proposed 
revised standards are based on the same technologies upon which the 
1997 final standards were based--good combustion and a moderate-
efficiency wet scrubber for new small HMIWI, and good combustion and a 
combined dry/wet control system with carbon for new medium and large 
HMIWI--and reflect the MACT floor emissions levels for new small and 
large HMIWI, but are more stringent than the MACT floor for new medium 
HMIWI. The rationale for these determinations regarding identification 
of MACT can be found at 62 FR 48365.
    As explained earlier in this preamble, we are proposing emission 
limits for each air pollutant for each subcategory of new HMIWI based 
on the highest observed data points associated with the control 
technologies upon which the emission standards are based, since we 
identified the ``best controlled similar unit'' as one using the 
relevant control technologies for each subcategory of new units. The 
proposed percent reduction limits for HCl, Pb, Cd, and Hg were 
established based on average combustion-controlled emissions estimates 
and highest observed data points associated with the control 
technologies upon which the emission standards for each of these 
pollutants for each subcategory are based. This is the same approach 
used at the time of promulgation with two exceptions--the proposed 
percent reduction limits do not include the addition of 10 percent

[[Page 5526]]

to the highest observed emissions levels, nor does it include the 
rounding up of those figures. A summary of the control technologies 
upon which the proposed standards for new HMIWI are based, the highest 
observed data points associated with those control technologies, and 
the proposed emission limits for new HMIWI in response to the remand 
are presented in Table 6 of this preamble. Note that MACT for 
NOX and SO2 are ``combustion control,'' although 
combustion control results in no emission reductions for those 
pollutants because NOX emissions are not reduced by 
combustion control, and NOX add-on controls have not been 
demonstrated on HMIWI; and SO2 emissions are not reduced by 
combustion control, and acid gas controls are not effective in reducing 
SO2 emissions from HMIWI at the low SO2 levels 
associated with HMIWI.

                                                   Table 6.--Summary of Remand Response for New HMIWI
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 Highest
          Pollutant  (units)                  Unit Size \1\                  MACT             observed data           Proposed emission limit \2\
                                                                                                point \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
HCl (ppmv)............................  L, M, S..................  Wet scrubber............            9.3    15 \3\ or 99% reduction \3\.
CO (ppmv).............................  L, M, S..................  Good combustion.........           32      32.
Pb (mg/dscm)..........................  L, M.....................  Dry scrubber w/carbon...            0.06   0.060 or 98% reduction \3\.
                                        S........................  Wet scrubber............            1.1    0.78 \4\ or 71% reduction.
Cd (mg/dscm)..........................  L, M.....................  Dry scrubber w/carbon...            0.03   0.030 or 93% reduction.
                                        S........................  Wet scrubber............            0.14   0.11 \4\ or 66% reduction \3\.
Hg (mg/dscm)..........................  L, M.....................  Dry scrubber w/carbon...            0.45   0.45 or 87% reduction.
                                        S........................  Wet scrubber............            0.47   0.47 or 87% reduction.
PM (gr/dscf)..........................  L, M.....................  Dry scrubber w/carbon...            0.009  0.0090.
                                        S........................  Moderate-efficiency wet             0.018  0.018.
                                                                    scrubber.
CDD/CDF, total (ng/dscm)..............  L, M.....................  Dry scrubber w/carbon...           20      20.
                                        S........................  Wet scrubber............          111      111.
CDD/CDF, TEQ (ng/dscm)................  L, M.....................  Dry scrubber w/carbon...            0.53   0.53.
                                        S........................  Wet scrubber............            2.1    2.1.
NOX (ppmv)............................  L, M, S..................  Combustion Control \5\..          225      225.
SO2 (ppmv)............................  L, M, S..................  Combustion Control \5\..           46      46.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small.
\2\ All values are measured at 7 percent oxygen.
\3\ No change proposed.
\4\ Remand standards for existing small non-rural HMIWI are proposed.
\5\ Combustion control results in no emissions reduction.

    Note that no change is proposed for the emission limit for HCl for 
new large, medium, and small HMIWI. In this situation, the highest 
observed emission point (i.e., 9.3 ppmv) is not used as a basis for the 
proposed emission limits. Public comments concerning use of EPA Method 
26A when testing for HCl emissions at sources with wet scrubbers were 
submitted with respect to the recently promulgated standards for other 
solid waste incineration units (70 FR 74870, December 16, 2005). The 
commenter asserted that EPA Method 26A is not adequate for 
demonstrating compliance with an HCl standard below 20 ppmv when 
sampling sources with wet scrubbers. Although EPA did not concede that 
there is an outright problem, we acknowledged that a tester may need to 
take certain precautions to ensure that there is no bias when sampling 
streams with low HCl concentrations in certain environments and 
promulgated an HCl emission limit of 15 ppmv (versus the proposed limit 
of 3.7 ppmv). Method 26A also notes that there is a possible measurable 
negative bias below 20 ppmv HCl perhaps due to reaction with small 
amounts of moisture in the probe and filter (40 CFR part 60, appendix 
A). Accordingly, because many of the wet-scrubber controlled HMIWI used 
Method 26A to measure HCl emissions below 20 ppmv and did not take 
precautions to ensure no negative bias, in this action we are proposing 
to retain the emission limit of 15 ppmv and also are including 
provisions that require sources to condition the filter before testing, 
and use a cyclone and post test purge if water droplets may be present. 
In the cases of Pb and Cd for new small HMIWI, using the highest 
observed data points would result in emission limits less stringent 
(i.e., higher) than the proposed emission limits for existing small 
non-rural HMIWI. Because the existing source analysis provides limits 
that can be achieved by existing HMIWI, there is no reason to believe 
that new HMIWI could not also meet the more stringent limits. This 
unanticipated result may be due to the small amount of Pb and Cd 
emissions data available for wet scrubbers at promulgation. Regardless, 
we are proposing emission limits for Pb and Cd for new small HMIWI that 
are the same as those proposed for existing small non-rural HMIWI.
2. Existing Units
    The Court raised three specific concerns regarding EPA's approach 
for existing units in concluding that EPA had not adequately explained 
why the combination of regulatory and uncontrolled (i.e., combustion-
controlled) data provided a ``reasonable estimate'' of HMIWI 
performance: ``First, EPA has said nothing about the possibility that 
[HMIWI] might be substantially overachieving the [regulatory] limits. 
[Footnote:] Although the agency conceded in its response to comments 
that `actual emission data routinely fall below the State permit 
emission limits,' [* * *] the context makes reasonably clear that the 
EPA was referring to data on `actual emissions' during tests; EPA 
implied that `these levels are not routinely achieved in practice.' [* 
* *] [End Footnote] If this were the case, the permit limits would be 
of little value in estimating the top 12 percent of [HMIWI]s' 
performance'' (167 F.3d at 663, and at n. 3). According to the Court, 
``[d]ata in the record suggest that the regulatory limits are in fact 
much higher than emissions that units achieve in practice.'' Id., at 
663.
    ``Second, EPA never gave any reason for its apparent belief that 
[HMIWI]s that were not subject to [regulatory limits] did not employ 
emission controls of any sort. Unless there is some finding to this 
effect, it is difficult to see the rationality in using `uncontrolled' 
data for the units that

[[Page 5527]]

were not subject to regulatory requirements'' (167 F.3d at 664). The 
Court pointed out that ``[d]ata submitted by the American Hospital 
Association [AHA] in 1995 indicate that over 55% of [HMIWI]s in each 
category were controlled by wet scrubbers.'' Id., footnote omitted. As 
a result, the Court found it ``difficult to see how it was rational to 
include any uncontrolled [i.e., combustion-controlled] units in the top 
12 percent, at least with respect to pollutants that wet scrubbing 
controls.'' Id.
    Third, the Court held that ``assuming the regulatory data was a 
good proxy for the better controlled units and that there were 
shortfalls in reaching the necessary 12 percent, EPA has never 
explained why it made sense to use the highest of its test run data to 
make up the gap.'' Id.
    Subsequent court decisions also addressed the type of information 
EPA may use to estimate emissions performance and establish MACT floors 
for existing units. In NLA II, the Court rejected the Sierra Club's 
claim that it was unreasonable for EPA to select ``the median 
[performing] plant out of the best twelve percent of the plants for 
which it had information and set the * * * floor at the level of the 
worst performing plant in its databases using th[e same] technology [as 
the median plant].'' 233 F.3d at 630. As long as EPA's estimate of the 
performance of the top 12 percent was reasonable, the Court held, EPA 
was not required to use actual emissions data. Id. While in CKRC the 
Court held that EPA had not justified in the HWC rulemaking basing the 
floor on emissions levels of the worst performing plant utilizing MACT 
control technology, when record evidence indicated other factors beyond 
MACT technology affected emissions performance, the Court reiterated 
that EPA could use estimates, as long as they reflected a 
``reasonable[] estimate [of] the performance of the * * * best-
performing plants.'' 255 F.3d at 862.
    Specifically regarding the use of State permits to determine MACT 
floors, the Court in Northeast Maryland Waste Disposal Authority v. 
EPA, 358 F.3d 936 (D.C. Cir. 2004) (``NMWDA''), rejected EPA's approach 
for small municipal waste combustion units because ``as in Sierra Club, 
EPA stated only that it `believes' state permit limits reasonably 
reflect the actual performance of the best performing units without 
explaining why this is so.'' 358 F.3d at 954. There, EPA had asserted 
that the inherent variability of emission levels made other data 
inaccurate, but the Court concluded that EPA gave ``no evidence that 
the [State] permit levels reflect the emission levels of the best-
performing'' units, and that EPA's stated ``belief'' did not rise to 
the level of a ``reasonable estimate.'' Id. However, in Mossville 
Envt'l Action Now v. EPA (370 F.3d 1232 (D.C. Cir. 2004)), the Court 
concluded that ``instead of simply claiming that it believes its 
[relied upon] standards estimate what the best five plants actually 
achieve, EPA points to some evidence. In its response to comments, EPA 
cited its analysis of three years of data, and * * * met its burden of 
establishing that its standards reasonably estimate the performance of 
the best five performing sources. Having cited the great variability of 
emission levels, even within the same plants, and the inherent 
difficulty in other standards it considered, the EPA's selection of the 
[relevant] standards as the MACT floor is reasonable because it has 
supported its decision with record data that shows the connection 
between its MACT floor and the top performing plants.'' 370 F.3d at 
1242.
    a. The Possibility that HMIWI Sources are Substantially 
Overachieving their Regulatory Limits. With regard to the Sierra Club 
Court's first concern, the Court itself noted early in its opinion that 
``the necessary relationship [of regulatory data serving as a 
reasonable proxy to indicate HMIWI performance] seems quite reasonable 
here. Indeed, it seems likely that any jurisdiction bothering to impose 
limits would not knowingly set them below what it found firms to be 
achieving in practice. And there seems no reason to think that 
underachieving firms would be overrepresented in jurisdictions making 
this effort.'' 167 F.3d at 662. The Court also expressed support for 
the notion that, when faced with limited actual emissions information, 
a substitute `` `reasonable sample' may be used `to find out what the 
best 12 percent are doing[,]' '' (id., citing Oral Arg. Tr. at 11), and 
that ``EPA typically has wide latitude in determining the extent of 
data-gathering necessary to solve a problem.'' Id. Specifically, the 
Court noted ``that since EPA had data on only one percent of about 3000 
[HMIWI]s, [* * *] the data-gathering costs of any non-sampling method 
may well have been daunting.'' Id., at 663.
    There are three reasons why EPA chose to use the regulatory limits 
at their face value in calculating the existing source MACT floor for 
the 1997 rule. First, regulatory data were used because there was very 
little actual emissions data available and very little data available 
indicating the type of air pollution control used by the best 
performing units. (See 61 FR at 31738.) None of the available 
information indicated that the regulated entities were substantially 
overachieving or underachieving their regulatory limits. Second, there 
was no information before the Agency suggesting that the State 
regulatory agencies erred in establishing the regulatory limits or that 
the States' regulatory limits were outdated. It was thus reasonable for 
EPA to expect that the State regulatory limits provided a reasonable 
estimate of the actual performance of HMIWI units. Third, it was 
reasonable for EPA to expect that regulated entities take their 
regulatory limits into account when designing their control equipment. 
To some extent, control equipment can be designed to meet various 
levels of emissions, and regulated entities do not normally spend more 
money than necessary to meet a regulatory limit. As noted above, the 
Court observed that ``there seems no reason to think that 
underachieving firms would be overrepresented'' by regulatory limits 
(167 F.3d at 662). Conversely, there is no reason to generally assume 
that substantially overachieving firms would be overrepresented in 
jurisdictions imposing regulatory limits. Rather, what is most likely 
is that sources in regulated jurisdictions will have assessed whether 
steps to control emissions are needed to comply with the regulatory 
limits, and that, in order to account for emissions variability when 
applying control technologies, they will be targeting their emissions 
levels at some safe point below the regulatory limits. Hence, with no 
information in the 1997 rulemaking record to indicate otherwise, EPA 
generally expected that regulatory limits were being achieved, through 
application of emissions control methods, at emissions levels that 
sources deem necessary in order to minimize the risk of violating the 
relevant limit, and were neither substantially overachieving the limits 
nor underachieving them.
    The Court noted that the administrative record indicated that, in 
some cases, sources were overachieving their regulatory limits, where 
the floors based on the weighted average of the regulatory limits and 
the ``uncontrolled'' (i.e., combustion-controlled) data were 
significantly higher than the values used for combustion-controlled 
data. (See 167 F.3d at 663, citing A-91-61, IV-B-024 at 2-3). Here, the 
Court was referring to some regulatory limits that, in fact, reflected 
higher emissions levels than did EPA's uncontrolled (i.e., combustion-
controlled) emission estimates, and suggested that in these cases it 
would be unreasonable for EPA to view the best performing 12 percent

[[Page 5528]]

of sources as actually polluting at levels so much higher than the test 
units for which EPA assumed no emissions controls were in place. Id., 
at 663-664.
    EPA agrees that a regulatory limit does not reflect ``actual 
performance'' when that limit is higher than the level attributed to 
the worst reasonably foreseeable performance of an uncontrolled (i.e., 
combustion-controlled) source. Since the data forming the basis for the 
existing source MACT floor must provide a reasonable estimation of the 
``actual performance'' of the best performing 12 percent of HMIWI, such 
high regulatory limits should not have been included in the best-
performing 12 percent. Therefore, in our re-visiting the MACT floor for 
existing HMIWI based on the 1997 record, in situations for which there 
is no information in the 1997 record indicating the presence of an add-
on pollution control device (``APCD'') or other use of air pollution 
control methods but there are regulatory limits, we propose the 
substitution of combustion-controlled data for regulatory limits where 
those data reflect lower emissions levels than do regulatory limits 
that appear to be unrelated to actual controls. We propose to continue 
to use combustion-controlled data in situations for which there is no 
information indicating air pollution controls are in use and there are 
no regulatory limits.
    b. Emission Control on HMIWI Not Subject to Regulatory Limits. The 
Court's second concern was that EPA had not made a finding that HMIWI 
that were not subject to regulatory requirements did not use emissions 
controls of any kind. The Court viewed such a finding as a necessary 
prerequisite to using uncontrolled (i.e., combustion-controlled) data 
for units not subject to regulatory requirements. This issue can be 
partly resolved by correcting a misunderstanding that may have resulted 
from our 1997 administrative record. The Court focused on information 
submitted in 1995 by the AHA suggesting that ``over 55% of [HMIWI]s in 
each category were controlled by wet scrubbers.'' (See 167 F.3d at 664, 
citing AHA Comments, Exhibit 3.) Based on its review of the AHA 
comments, the Court assumed that under EPA's estimation of the HMIWI 
population, more than 12 percent in each category ``would as a matter 
of mathematical necessity have to be controlled.'' Id., at 664, n. 8. 
The Court then observed that ``it is difficult to see how it was 
rational to include any uncontrolled [i.e., combustion-controlled] 
units in the top 12 percent, at least with respect to pollutants that 
wet scrubbing controls.'' Id., at 664.
    With regard to the AHA ``data'' identified by the Court as 
indicating 55 percent of HMIWI use wet scrubbers, EPA believes that the 
Court was led by this information into assuming that unregulated HMIWI 
were in fact applying add-on emissions controls, when the record does 
not actually substantiate such an assumption, especially for small 
HMIWI. The AHA asserts ``almost all properly designed, operated, and 
controlled [HMIWI] can readily meet a particulate emission limit of 
0.10 gr/dscf without an [add-on air pollution control] system'' (IV-D-
637, Exhibit 2, emphasis added). The AHA then concludes ``[t]herefore, 
it is reasonable that as many as 50 percent of those [HMIWI] having 
such an emission limit would be uncontrolled.'' Id. The AHA goes on to 
assume that 50 percent of all HMIWI with particulate emission limits of 
0.10 gr/dscf or higher are controlled with wet scrubbers, while an even 
higher percentage of units with more stringent particulate emission 
limits are assumed to be controlled. Id. This is akin to saying that, 
because homeowners are generally not required to install wet scrubbers 
on fireplaces, it is reasonable to assume that as many as 50 percent of 
homes with fireplaces do not have wet scrubbers, while the other 50 
percent of home fireplaces are equipped with wet scrubbers. The AHA 
makes a basic assumption that at least 50 percent of all HMIWI have wet 
scrubbers, no matter what requirements they are subject to. With no 
other information to support its assumption, AHA's ``data'' indicating 
55 percent of HMIWI are equipped with wet scrubbers is altogether 
unreliable. In addition, EPA's documented difficulty in identifying 
sources with add-on controls during the development of the HMIWI 
emission testing program is in direct conflict with the large number of 
controlled sources suggested by the AHA ``data.''
    Based on information from various sources in the docket from the 
1997 rulemaking, including an AHA HMIWI inventory, we now estimate that 
about 32 percent of large, 4 percent of medium, and 1 percent of small 
HMIWI at the time of the 1997 rulemaking were equipped with add-on 
control systems. Other sources in the 1997 record that provided an 
indication of whether or not HMIWI were equipped with add-on air 
pollution control and upon which these estimates are based include a 
survey of HMIWI in California and New York, air permits from State 
regulatory agencies, responses to information collection requests, 
telephone contact summaries, HMIWI emissions test reports, and various 
inventories. (See Legacy Docket ID No. A-91-61, items IV-J-82, IV-B-07, 
II-B-94, II-D-175 through 178, II-I-151, IV-J-89, IV-E-65, IV-E-74, IV-
E-86, and II-B-61; Docket EPA-HQ-OAR-2006-0534, document titled ``List 
of Test Reports Used to Identify HMIWI Control Devices''). Our 
assessment that few HMIWI were equipped with add-on controls is also 
supported by economics in that it would not have made sense for an 
HMIWI to be voluntarily equipped with an air pollution control device 
that costs one to three or more times as much as the entire HMIWI. 
Further supporting our assessment is the fact that the expected outcome 
of the regulation (which was not refuted by any commenters), that 50 to 
80 percent of existing incinerators (including 100 percent of the small 
units) would shut down rather than meet the regulations because those 
that chose to meet the regulations would have to install air pollution 
control to comply, was, in fact, more than realized. (See 60 FR 10665, 
61 FR 31768, and 62 FR 48372.) In fact, all but 8 small units, 6 of 
which meet the rural criteria and did not have to install air pollution 
control to comply, 20 medium units, and 44 large units have shut down, 
rather than meet the standards that would have been achieved by use of 
the very controls AHA appeared to assume were in place. Consequently, 
EPA concludes that the 1997 record, as confirmed by recent data showing 
the vast reduction in sources (as opposed to sources installing 
controls), shows that most HMIWI were not equipped with add-on air 
pollution control and that the use of uncontrolled (i.e., combustion-
controlled) emission estimates where there was no indication of air 
pollution control (and where any applicable regulatory limits allowed 
higher levels of emissions than our combustion-controlled emissions 
values reflected) was warranted. Based on the number of HMIWI 
shutdowns, it appears very likely that there were even fewer HMIWI with 
air pollution controls than we estimated based on the information 
discussed above (i.e., that about 32 percent of large, 4 percent of 
medium, and 1 percent of small HMIWI were equipped with add-on control 
systems).
    c. EPA's Use of the Highest Emissions Data to Reflect Uncontrolled 
(i.e., Combustion-Controlled) Emissions. The Court's third concern 
regarded our use of the highest of the test run data to reflect 
uncontrolled (i.e., combustion-controlled) emissions in cases where 
regulatory data did not comprise the

[[Page 5529]]

necessary 12 percent of best performing sources. Our reason for this 
approach is the same as the reason described earlier regarding new 
units for using the highest data point from MACT-particular technology 
to reflect the performance of that technology and identify the ``best 
controlled similar unit.'' As the Court stated in NLA I, ``where test 
results are relied upon, it should involve the selection or use of test 
results in a manner which provides some assurance of the achievability 
of the standard for the industry as a whole, given the range of 
variable factors found relevant to the standard's achievability.'' (See 
627 F.2d at 433). EPA reads the Court's opinion in Sierra Club as at 
least endorsing the principles of NLA I with respect to existing units, 
as the Court described as ``counterintuitive'' the Sierra Club's 
``proposition that an `achieved' level may not be `achievable[.]' '' 
(See 167 F.3d at 662). In addition, we also read CKRC as allowing this 
approach, where no evidence in the record contradicts the assumption 
that ``factors other than the control have a negligible effect [on 
emissions performance],'' 255 F.3d at 866, and, therefore, the presence 
or absence of known effective MACT controls is the prime determinant of 
emissions performance.
    Where regulatory data indicating use of emissions control was 
absent in the 1997 rulemaking record, EPA needed to find a surrogate 
emission limitation that reflected uncontrolled (i.e., combustion-
controlled) emissions, expecting, when not faced with data indicating 
otherwise, that facilities with no regulatory limits would not be 
controlling their emissions with add-on controls or other control 
methods (beyond combustion control). In this situation, EPA used the 
highest test data point from a well-operated HMIWI as a surrogate for 
the worst reasonably foreseeable circumstances. The highest test data 
points reflect the normal, and unavoidable, variation in emissions that 
would be expected to recur over time. Table 7 of this preamble 
summarizes the performance values used for units for which there is no 
information indicating an APCD is present and there are no regulatory 
limits, or where regulatory limits do exist but reflect emissions 
levels that are higher than the values for uncontrolled (i.e., 
combustion-controlled) units.

 Table 7.--Uncontrolled (i.e., Combustion-Controlled) Performance Values
------------------------------------------------------------------------
                                                            Performance
                    Pollutant  (units)                       value \1\
------------------------------------------------------------------------
HCl (ppmv)...............................................      2,770
CO (ppmv) -..............................................    \1\ 584.9
Pb (micrograms per dry standard cubic meter [mu]g/dscm)..      8,629
Cd ([mu]g/dscm)..........................................      3,520
Hg ([mu]g/dscm)..........................................      6,543.4
PM (gr/dscf).............................................      \2\ 0.278
CDD/CDF, total (ng/dscm).................................  \2\ 8,102
CDD/CDF, TEQ (ng/dscm)...................................    \2\ 236
NOX (ppmv)...............................................        224.5
SO2 (ppmv)...............................................         46.39
------------------------------------------------------------------------
\1\ All performance values are measured at 7 percent oxygen.
\2\ Based on 1-second combustion level

    d. Determining the MACT Floor and MACT for Existing Units. As 
discussed above, the Sierra Club Court identified some potential errors 
in EPA's methodology for determining the existing source MACT floors 
for HMIWI. After reviewing the 1997 HMIWI record in the context of the 
Court's opinion, EPA agrees that, in determining the MACT floor, the 
Agency should not have used regulatory limits that reflected higher 
emissions levels (and that did not appear to be related to any air 
pollution controls) than those corresponding to EPA's combustion-
controlled emission estimates. Furthermore, as we examined the 1997 
record and our estimates of the performance of HMIWI where we had some 
indication that add-on controls may have been used, we determined that 
we should not have used combustion-controlled emission estimates in the 
floor calculations to represent the performance of those sources. 
Additionally, for this rulemaking we propose that where actual 
emissions test data reflecting emissions performance was available in 
the 1997 record for use in determining the MACT floor, that data should 
take precedence over other types of data (i.e., regulatory limits or 
performance values).
    EPA's reassessment of the 1997 MACT floors and MACT decisions, 
based on an adjusted methodology that addresses the Court's issues 
discussed above, results in proposed emission limits that in many cases 
are more stringent than the limits promulgated in 1997. EPA's first 
step in redoing the MACT analysis based on the 1997 record for existing 
HMIWI was to determine the pollutant-specific values that make up the 
best performing 12 percent of existing units within each size category. 
Actual test data, where available in the 1997 record, were the initial 
type of pollutant-specific values considered. Next, where the 1997 
record has information indicating that a source employed some type of 
add-on control but there are no test data or regulatory limits for that 
source, an average of the maximum dry and wet control system 
performance was determined for each pollutant, and those values were 
added to the data set towards comprising the best performing 12 
percent. We believe that use of these averages is an appropriate method 
of estimating the performance of HMIWI (1) where the 1997 record has 
limited information indicating the presence of some type of add-on 
control but no test data for the unit, and (2) where we are unsure if 
the control is similar to, or is as efficient as, those for which we 
have data, or if the unit even employed a true control device. As 
previously stated, we believe it very likely that there were fewer 
HMIWI with air pollution controls than we estimated in 1997, and to 
which we have assigned pollutant-specific average control device 
values. If, in fact, those sources were employing true control devices, 
common sense dictates that there wouldn't have been the large number of 
unit shut downs that occurred in response to the promulgated standards. 
However, because we had some indication that an add-on control device 
was in place on those sources, we recognize that the use of 
uncontrolled (i.e., combustion-controlled) emission estimates (at 
promulgation) did not provide a reasonable estimate of their 
performance. Similarly, use of performance values associated with a 
specific type of add-on control device seems inappropriate when no 
details are available on the control device and there is, in fact, some 
doubt as to the presence of a true control device at all. Despite the 
doubts of the presence of a true control device, the approach we have 
selected assumes that the 1997 record is correct and assigns 
``default'' performance values to the units that are based on the 
expected performance of the types of control devices used in the 
industry in 1997. These default performance values, based on the 
average of the maximum dry and wet control system performance, also are 
used where regulatory limits exist but are higher than the default 
performance values.
    Table 8 of this preamble summarizes the performance values for HCl, 
Pb, Cd, Hg, CDD/CDF, and PM for units for which the 1997 record has 
information indicating that they employed some

[[Page 5530]]

type of add-on control but has no test data or regulatory limits 
corresponding to specific controls, or where regulatory limits exist 
but are higher than the values based on an average of the maximum dry 
and wet control system performance.

  Table 8.--Performance Values Based on Average of Maximum Dry and Wet
                       Control System Performance
------------------------------------------------------------------------
                                                            Performance
                    Pollutant  (units)                       value \1\
------------------------------------------------------------------------
HCl (ppmv)...............................................        53.165
Pb ([mu]g/dscm)..........................................       568.5
Cd ([mu]g/dscm)..........................................        83.65
Hg ([mu]g/dscm)..........................................       459.5
PM (gr/dscf).............................................         0.0195
CDD/CDF, total (ng/dscm).................................        65.35
CDD/CDF, TEQ (ng/dscm)...................................         1.296
------------------------------------------------------------------------
\1\ All performance values are measured at 7 percent oxygen.

    The values for CO, NOX and SO2 are based on 
the performance of combustion-controlled HMIWI because, as stated at 
proposal and promulgation of the 1997 HMIWI standards, as well as 
earlier in this preamble, CO emission levels are affected by combustion 
practices rather than the control systems used by HMIWI; NOX 
control had not been demonstrated on HMIWI; and the acid gas controls 
used by HMIWI were not effective in reducing SO2 emissions 
from HMIWI due to the low inlet levels of SO2 associated 
with hospital/medical/infectious waste. Therefore, for units (1) where 
the 1997 record contains information indicating that they employed some 
type of add-on control but for which there was no test data or 
regulatory limits, or (2) where regulatory limits existed but were 
higher than the values for CO, NOX, or SO2 based 
on combustion-controlled HMIWI, the performance values for CO (584.9 
ppmv), NOX (224.5 ppmv), and SO2 (46.39 ppmv) are 
the same as those presented in Table 7 of this preamble.
    The next step in the MACT analysis for existing HMIWI was to 
determine the average emission limitation achieved by the best-
performing 12 percent of existing sources where there are 30 or more 
sources in the category or subcategory. Our general approach to 
identifying the average emission limitation has been to use a measure 
of central tendency, such as the arithmetic mean or the median. If the 
median is used when there are at least 30 sources, then the emission 
level that is at the bottom of the best performing 6 percent of sources 
(i.e., the 94th percentile) represents the MACT floor control level. We 
based our MACT floors for each pollutant within each size category on 
this approach. We then determined the technology associated with each 
``average of the best-performing 12 percent'' value by comparing the 
average values to average performance data for wet scrubbers, dry 
injection fabric filters (also known as dry scrubbers), and combustion 
controls (no add-on air pollution controls). Those pollutants with 
average values that were higher than the relevant combustion-controlled 
emission estimate were identified as having a ``combustion control'' 
floor, even if the pollutant is not reduced by combustion control. The 
technology needed to meet the remaining average values reflects the 
technology used by the average unit in the top 12 percent and serves as 
the basis for the MACT floor. EPA then considered, on a pollutant-
specific basis, technologies that were more stringent than the MACT 
floor technologies.
    Add-on control technology-based MACT floors were identified for 
large HMIWI for HCl, Pb, Cd, Hg, PM, and CDD/CDF. The MACT floor 
technology for all size units for NOX and SO2 is 
``combustion control'' although, as previously explained in this 
preamble, combustion control results in no emission reductions for 
those pollutants. ``Good combustion'' (i.e., 2-second combustion) was 
identified as the MACT floor technology for all size units for CO. 
``Combustion control'' floors were identified for medium HMIWI for Pb, 
Cd, Hg, and CDD/CDF and for small HMIWI for HCl, Pb, Cd, Hg, and CDD/
CDF. However, for these pollutants for all medium and most small HMIWI, 
we have decided to propose limits that are more stringent than the 
``combustion control'' floors and are consistent with the control 
technology-based MACT floors that were identified for large HMIWI for 
these pollutants (i.e., Pb, Cd, Hg, and CDD/CDF for medium HMIWI and 
HCl, Pb, Cd, Hg, and CDD/CDF for small HMIWI). The control technologies 
identified as the MACT floors for HCl and PM for medium HMIWI, and for 
PM for small HMIWI, provide an indication of the level of control of 
the other pollutants--a level of technology that is consistent with 
those technologies identified for large HMIWI. The rationale for not 
basing the proposed emission limits on other technologies that would 
result in even more stringent limits can be found at 62 FR 48371-72. As 
at the 1997 promulgation, MACT for small HMIWI that meet certain 
``rural criteria'' was determined to be at the MACT floor level for 
each pollutant (i.e., no ``beyond-the-floor''-based emission limits).
    Table 9 of this preamble shows the average emission value, based on 
the ranking of emissions data, regulatory data, and performance data, 
of each pollutant for the top 12 percent of HMIWI in each subcategory. 
The values in Table 9 allow EPA to identify the technology associated 
with the average unit in the top 12 percent of HMIWI.

   Table 9.-- Average Emission Values for Top 12 Percent of Hmiwi \1\
------------------------------------------------------------------------
                                                  HMIWI size
          Pollutant (units)          -----------------------------------
                                         Small      Medium       Large
------------------------------------------------------------------------
HCl (ppmv)..........................   2,770          53          50
CO (ppmv)...........................     100         100         100
Pb (mg/dscm)........................       8.63        8.63        0.569
Cd (mg/dscm)........................       3.52        3.52        0.084
Hg (mg/dscm)........................       6.54        4.27        0.460
PM (gr/dscf)........................       0.080       0.030       0.020
CDD/CDF, total (ng/dscm)............   8,102       8,102          65.4
CDD/CDF, TEQ (ng/dscm)..............     236         236           1.30
NOX (ppmv)..........................     225         225         225
SO2 (ppmv)..........................      46.4        46.4        46.4
------------------------------------------------------------------------
\1\ All emission values are measured at 7 percent oxygen.

[[Page 5531]]

    Table 10 of this preamble shows the technology associated with each 
average emission value.

                                        Table 10.--MACT Floor Technology
----------------------------------------------------------------------------------------------------------------
                                                                       HMIWI Size
          Pollutant (units)           --------------------------------------------------------------------------
                                                Small                    Medium                   Large
----------------------------------------------------------------------------------------------------------------
HCl (ppmv)...........................  combustion control.....  dry scrubber...........  dry scrubber.
CO (ppmv)............................  good combustion........  good combustion........  good combustion.
Pb (mg/dscm).........................  combustion control.....  combustion control.....  wet scrubber.
Cd (mg/dscm).........................  combustion control.....  combustion control.....  wet scrubber.
Hg (mg/dscm).........................  combustion control.....  combustion control.....  dry scrubber.
PM (gr/dscf).........................  low-efficiency wet       moderate-efficiency wet  moderate-efficiency wet
                                        scrubbber.               scrubber.                scrubber.
CDD/CDF, total (ng/dscm).............  combustion control.....  combustion control.....  wet scrubber.
CDD/CDF, TEQ (ng/dscm)...............  combustion control.....  combustion control.....  wet scrubber.
NOX (ppmv)...........................  combustion control.....  combustion control.....  combustion control.
SO2 (ppmv)...........................  combustion control.....  combustion control.....  combustion control.
----------------------------------------------------------------------------------------------------------------

    For small units, the CO and PM values indicate that good combustion 
control (i.e., 2-second combustion) and a low-efficiency wet scrubber 
reflect the CO and PM MACT floors. For medium units, as well as large 
units, the CO, HCl, and PM values indicate that good combustion control 
used in conjunction with either a dry scrubber or moderate-efficiency 
wet scrubber reflects the CO, HCl, and PM MACT floors. As previously 
stated, EPA concluded that emission limits for small units that meet 
the rural criteria should reflect the MACT floor level of control for 
all pollutants. The average emission value and MACT floor level of 
control for PM vary by unit size, and we are proposing emission limits 
based on those levels of control. The average emission values, and 
associated MACT floor levels of control, for CO, NOX, and 
SO2 are the same for all size units. For most small units 
and all medium units, however, we concluded that emission limits for 
HCl, Pb, Cd, Hg, and CDD/CDF should reflect the MACT floor level of 
control for large units for those pollutants.
    The resulting numerical emission limits were determined by 
combining the appropriate average emission value for each pollutant for 
each size HMIWI with a variability factor. We believe it is necessary 
to account for variability given the limited amount of actual data 
available in the 1997 record and the resulting need for use of various, 
and often presumptive, types of information to formulate the best 
performing 12 percent of HMIWI. At promulgation, we recognized the need 
to account for variability and did so as described earlier in this 
preamble. Although we maintain that the methodology we used was not 
unreasonable given the available information at promulgation, we now 
have additional information (the 2002 compliance test data for all of 
the currently operating units) for use in calculating pollutant-
specific variability factors. While these data were not available at 
promulgation, they are the only data available for providing a 
quantitative assessment of variability of emissions from well-
controlled HMIWI. To determine the pollutant-specific variability 
factors, a statistical analysis was conducted. Specifically, the 
emission limit achievable for each pollutant was determined based on 
the combination of actual emissions test data, regulatory data, and 
estimated performance levels (as described earlier) and a statistics-
based variability factor calculated for each pollutant. To calculate 
the variability factors, we used the general equation: variability 
factor = t * standard deviation. This general equation has been used by 
EPA in similar analyses. (See, e.g., 68 FR 27650; 69 FR 55235-7; 70 FR 
28615.) We selected the 90th percentile confidence level for this one-
sided t-statistics test. The 90th percentile provides a variability 
factor appropriate for well-controlled sources that is based on data 
from well-controlled sources (i.e., the only sources that are still in 
operation).
    Table 11 of this preamble presents the values determined by adding 
the variability factors to the average emission values for each 
pollutant for existing large and medium HMIWI. The table also presents 
the proposed revised emission limits for existing large and medium 
HMIWI necessary to respond to the Court's remand and the percent 
reduction limits for HCl, Pb, Cd, and Hg. The percent reduction limits 
are based on average combustion-controlled emissions estimates and 
maximum performance values for the MACT identified for each pollutant 
for each subcategory. This is the same approach used at the time of 
promulgation of the 1997 rule, except that the proposed percent 
reduction limits do not include the addition of 10 percent to the 
maximum performance values or the rounding up of those figures.

 Table 11.--Average Emission Values, Considering Variability, and Emission Limits \1\--Existing Large and Medium
                                                      HMIWI
----------------------------------------------------------------------------------------------------------------
                                                      Large                                Medium
                                     ---------------------------------------------------------------------------
         Pollutant  (units)             Average +                             Average +
                                       variability      Emission  limit      variability      Emission  limit
----------------------------------------------------------------------------------------------------------------
HCl (ppmv)..........................        78      78 or 93% reduction           57.9    78 \3\ or 93%
                                                     \2\.                                  reduction \2\.
CO (ppmv)...........................       110      40 \2\................       113      40 \2\
Pb (mg/dscm)........................         0.78   0.78 or 71% reduction.         9.02   0.78 \3\ or 71%
                                                                                           reduction \3\.
Cd (mg/dscm)........................         0.11   0.11 or 66% reduction.         3.56   0.11 \3\ or 66%
                                                                                           reduction \2\.
Hg (mg/dscm)........................         0.64   0.55 \2\ or 87%                4.34   0.55 \2\ or 87%
                                                     reduction.                            reduction \3\.
PM (gr/dscf)........................         0.025  0.015 \2\.............         0.043  0.030 \2\

[[Page 5532]]

CDD/CDF, total (ng/dscm)............       115      115...................     8,150      115 \3\
CDD/CDF, TEQ (ng/dscm)..............         2.16   2.2...................       237      2.2 \3\
NOX (ppmv)..........................       284      250 \2\...............       273      250 \2\
SO2 (ppmv)..........................        61      55 \2\................        51.8    55 \2\
----------------------------------------------------------------------------------------------------------------
\1\ All emission values are measured at 7 percent oxygen.
\2\ No change from current emission limit.
\3\ Emission limit is the same as that for large HMIWI.

    Table 12 of this preamble presents the same information for 
existing small non-rural HMIWI and for existing small HMIWI meeting the 
rural criteria.

 Table 12.-- Average Emission Values, Considering Variability, and Emission Limits \1\--Existing Small And Small
                                                   Rural HMIWI
----------------------------------------------------------------------------------------------------------------
                                                             Large                              Medium
                                          ----------------------------------------------------------------------
            Pollutant  (units)               Average +                                  Average +     Emission
                                            variability         Emission limit         variability      limit
----------------------------------------------------------------------------------------------------------------
HCl (ppmv)...............................     2,772      78 \3\ or 93% reduction         3,125      \2\ 3,100
                                                          \2\..
CO (ppmv)................................       103      40 \2\.....................       109        \2\ 40
Pb (mg/dscm).............................         8.85   0.78 \3\ or 71% reduction           8.88          8.9
                                                          \3\.
Cd (mg/dscm).............................         3.54   0.11 \3\ or 66% reduction           3.54          4
                                                          \2\.
Hg (mg/dscm).............................         6.55   0.55 \2\ or 87% reduction           6.56          6.6
                                                          \3\.
PM (gr/dscf).............................         0.095  0.050 \2\..................         0.089     \2\ 0.086
CDD/CDF, total (ng/dscm).................     8,335      115 \3\....................     8,518       \2\ 800
CDD/CDF, TEQ (ng/dscm)...................       239      2.2 \3\....................       244        \2\ 15
NOX (ppmv)...............................       225      250 \2\....................       273       \2\ 250
SO2 (ppmv)...............................        46.4    55 \2\.....................        51.8     \2\ 55
----------------------------------------------------------------------------------------------------------------
\1\ All emission values are measured at 7 percent oxygen.
\2\ No change from current emission limit.
\3\ Emission limit is the same as that for large HMIWI.

    For pollutants where this remand analysis (based on the average of 
the best performing 12 percent of HMIWI plus the variability factor) 
resulted in emission limits less stringent (i.e., higher) than the 
current emission limits, we retained the current emission limits. This 
is because we see no reason to upwardly revise standards that the 
regulated industry has already demonstrated are achievable based on 
compliance data. In fact, now that we have received the 2002 compliance 
data for HMIWI units, it is apparent that EPA's estimate of the 
achievable emissions performance levels from use of the identified MACT 
technology was reasonably accurate. While we are not in this proposal 
attempting to justify our prior existing unit MACT floor decisions post 
hoc based on new data that we could not have relied upon in the 1997 
rulemaking itself, we note that, similar to the Mossville case, we 
currently find ourselves in a situation where actual emissions data 
fairly confirms our prior estimates of what the best controlled HMIWI 
units could achieve when using MACT controls.
    The resulting emission limits being proposed for medium HMIWI for 
HCl and SO2; for small HMIWI for NOX and 
SO2; and for small rural HMIWI for SO2 are the 
same as those being proposed for large HMIWI because, in these 
instances, the medium, small, and small rural HMIWI are expected to 
achieve reductions similar to large HMIWI.

B. Rationale for the Proposed Amendments (CAA Section 129(a)(5) 5-Year 
Review)

    In recent rulemakings (see, e.g., 71 FR 34422, 34436-38 (June 14, 
2006) (proposed amendments to the NESHAP for Hazardous Air Pollutants 
for Organic Hazardous Air Pollutants from the Synthetic Organic 
Chemical manufacturing Industry)) EPA has addressed the similar 
technology review requirement under CAA section 112(d)(6). EPA stated 
that the statute provides the Agency with broad discretion to revise 
MACT standards as we determine necessary, and to account for a wide 
range of relevant factors, including risk. EPA does not interpret such 
technology review requirements to require another analysis of MACT 
floors for existing and new units, but rather requires us to consider 
developments in pollution control in the industry and assess the costs 
of potentially stricter standards reflecting those developments. (See, 
id., at 34436-47.) Moreover, as a general matter, EPA has stated that 
where we determine that existing standards are adequate to protect 
public health with an ample margin of safety and prevent adverse 
environmental effects, it is unlikely that EPA would revise MACT 
standards merely to reflect advances in air pollution control 
technology. Id., at 34437-38.
    Under CAA section 112(d)(6), the first round of technology review 
for MACT standards is subject to the same statutory timeframe as EPA's 
residual risk review under CAA section 112(f)(2), with both reviews 
occurring 8 years following initial promulgation of MACT. We interpret 
CAA section 129(a)(5)'s technology review

[[Page 5533]]

requirement as providing us the same degree of discretion in terms of 
whether to revise MACT standards, for the reasons discussed in those 
prior rulemakings. (See, id., at 34436-38.) However, the deadline for 
the first round of technology review under section 129(a)(5) (5 years 
following MACT promulgation) does not coincide with the deadline for 
residual risk review under section 112(f)(2) (9 years, in the case of 
HMIWI standards). Therefore, this first section 129(a)(5) technology 
review for HMIWI does not account for or reflect our residual risk 
analysis. In future rounds of review under section 129(a)(5) for the 
HMIWI standards, we intend to follow our general policy, and for our 
technology reviews and conclusions to be informed by our residual risk 
analysis, which we will have performed by that point.
    In exercising its discretion under CAA section 129(a)(5), EPA is 
proposing in this technology review to adopt emission limits based on 
the 2002 data because it believes that these limits represent the cost-
effective operation of the MACT control technology. EPA is aware of the 
possibility that regulated units are likely to operate at a level 
somewhat below emission standards in order to account for operational 
variability. It is not our intent to preclude this practice through 
successive rounds of the section 129(a)(5) technology review. EPA 
requests comment on its proposal (as outlined below) to adopt more 
stringent emission limits in this instance through its section 
129(a)(5) technology review.
1. How were the proposed emission limits developed?
    The proposed revised emission limits resulting from our 5-year 
review of the HMIWI standards under section 129(a)(5) of the CAA are 
based on the performance of units within the industry that currently 
are subject to the MACT standards. One set of emission limits is 
proposed for existing HMIWI regulated under CAA section 111(d)/129(b) 
emission guidelines, and another set of emission limits is proposed for 
new HMIWI (units commencing construction after February 6, 2007) 
regulated under CAA section 111(b)/129(a) NSPS. Units that were subject 
to the 1997 NSPS as new units (referred to as ``1997 NSPS units'' for 
the remainder of this preamble) will remain subject to the 1997 NSPS 
(including revisions resulting from EPA's response to the Court 
remand), but will also be subject to any requirements of the revised 
emission guidelines that are more stringent than the 1997 NSPS 
requirements. The proposed emission limits for existing units, 1997 
NSPS units, and new units were developed following the procedures 
discussed below.
    As background, with one exception resulting from the analyses 
associated with our response to the Court remand, the proposed emission 
limits for new and existing units are based on the application of the 
same control technologies upon which the 1997 MACT standards were 
based. For new large and medium units, both the current and proposed 
emission limits are based upon good combustion and the application of 
combined control systems that include both dry scrubbers (i.e., dry 
injection fabric filters or spray dryer fabric filters) with carbon 
injection and wet scrubbers. The current and proposed emission limits 
for new small units are based on good combustion and the application of 
a moderate-efficiency wet scrubber. For large, medium, and most small 
existing units, the current and proposed emission limits are based on 
good combustion control for CO; combustion controls (i.e., no add-on 
controls) for NOX and SO2; and the application of 
either dry scrubbers or wet scrubbers (with various ``efficiencies'' 
depending on the size of the unit) for the remaining pollutants. The 
current emission limits for one additional subcategory, existing small 
rural units, are based solely on good combustion (i.e., the MACT floor 
identified in the 1997 analysis was not based on add-on control 
technology). With the exception of PM, the proposed emission limits for 
existing small rural units also are based solely on good combustion. In 
our remand analysis, we identified a low-efficiency wet scrubber as 
being the MACT floor for PM for these units. Although all small rural 
units currently use only good combustion, to address this difference in 
the MACT floors (i.e., 1997 analysis versus remand analysis), we are 
proposing a PM emission limit for existing small rural units based on 
the application of low-efficiency wet scrubbers to existing small non-
rural units (i.e., MACT floor for small non-rural units in the 1997 
analysis as well as the remand analysis). While this performance level 
is associated with the expected performance of a low-efficiency wet 
scrubber, the combustion controls in place on these six existing small 
rural units achieve this performance level, based on the initial 
compliance tests for these units.
    In performing this 5-year review, we have not recalculated new MACT 
floors, but have proposed to revise the emission limits to reflect the 
actual performance of the MACT technologies. We believe this approach 
reflects the most reasonable interpretation of the review requirement 
of CAA section 129(a)(5), and is consistent with how we have 
interpreted the similar review requirement of CAA section 112(d)(6) 
regarding MACT standards promulgated under section 112. (See 71 FR 
27327-28; 69 FR 48350-51; and 70 FR 20008.) The language of section 
129(a)(5) directs EPA to ``review'' our promulgated standards under CAA 
section 111/129, and to ``revise such standards and requirements'' ``in 
accordance with this section and section 111.'' It does not, however, 
direct EPA to conduct, at 5-year-intervals, new MACT floor and beyond-
floor analyses based on each 5-years' changing information as to what 
might comprise the top 12 percent of sources or constitute the best 
controlled similar unit. There is no indication that Congress intended 
for section 129(a)(5) to inexorably force existing source standards 
progressively lower and lower in each successive review cycle, the 
likely result of requiring successive floor determinations.
    Following MACT compliance in September 2002, EPA obtained 
compliance test reports from all operating HMIWI (76 units at 70 
facilities) and used those data to evaluate MACT performance. When the 
HMIWI regulations were first proposed in 1995, re-proposed in 1996, and 
promulgated in 1997, only limited information was available about HMIWI 
emission controls, and significant engineering judgment was necessary 
in selecting the emission limits. The year 2002 compliance data show 
that the control technologies that were installed and the practices 
that were implemented to meet the 1997 NSPS and emission guidelines 
achieved reductions somewhat superior to what we expected under the 
1997 limits for many of the pollutants. EPA used the compliance test 
data to develop the emission limits contained in the amendments we are 
proposing under the 5-year review. EPA believes that the proposed 
emission limits more accurately reflect actual real-world HMIWI MACT 
performance than what we had estimated in 1997 and what we re-estimated 
based on the 1997 record in response to the Court's remand (discussed 
previously in this preamble). We believe that it is necessary, as well 
as appropriate, to update the 1997 promulgated standards based on the 
actual performance of MACT technologies in situations where compliance 
test data indicate that the technologies achieve better performance 
levels than those we previously

[[Page 5534]]

estimated based on the information available at the time of 
promulgation.
    a. Existing Units. The first step in the analysis was to assess the 
performance of the HMIWI currently subject to the emission guidelines 
with respect to each regulated pollutant. We first examined the data 
separately for each unit size, and the data showed, for all pollutants 
except PM, that the performance of units with add-on controls, 
regardless of size, (excluding small rural units, which do not employ 
add-on controls), is similar. Therefore, we combined the data, 
regardless of unit size, for all of the pollutants except PM, and 
conducted analyses on the combined data sets. In addition, for the 
pollutants with emission limits based on good combustion and combustion 
control (i.e., no add-on controls), namely CO, NOX, and 
SO2, the data for small rural units also were combined with 
the data for all of the other subcategories of units. Analyses were 
performed on each data set, and we calculated the 99 percent upper 
tolerance limit (UTL), which is the emission level that 99 percent of 
the HMIWI would be expected to achieve. A similar methodology was used 
for stack test-based emission limits in the 5-year review recently 
conducted for large municipal waste combustors (MWC). In the preamble 
to that final action, EPA indicated that analysis of data to estimate 
emission limits to be enforced by stack test methods must be done using 
a different approach (i.e., lower percent UTL) than where enforcement 
is to be based on CEMS and that the percentile must also reflect a 
reasonable consideration of emissions variability and compliance 
limitations of stack testing (See 71 FR 27329). EPA further indicated 
that for this type of technology review, the 99 percent UTL was 
appropriate to use as a tool for estimating achievable emission levels 
for emission limits enforced by stack testing. Id. In this proposed 
rulemaking, the 99 percent UTL was used as the starting point for 
selecting the revised emission limits. We compared the 99 percent UTL 
values to several other values, including the 1997 promulgated emission 
limits and the revised limits that we are proposing in response to the 
Court's remand (``remand limits''). For several pollutants, the value 
associated with the 99 percent UTL was higher than the remand limit. In 
these cases, we selected the remand limit, rather than the 99 percent 
UTL value, as the proposed emission limit. We also graphically compared 
the 99 percent values and remand limits, where applicable, to all of 
the data that were used to calculate the percentile values. In many 
cases, this visual comparison revealed that the 99 percent UTL value or 
remand limit fell within a break in the data that indicated a level of 
performance that the technologies, considering variability, could 
readily achieve but that the ``worst performing'' units were not 
achieving during their compliance tests. Thus, our analyses indicate 
that the emission limits that we selected reflect the actual 
performance of the MACT control technologies while also serving to 
require modest improvements in performance from units that are not 
achieving the performance levels demonstrated in practice by the 
control technologies currently being used in the industry.
    For small non-rural HMIWI, we used a different methodology for 
assessing PM performance because there are only two units and, 
therefore, statistics are not a useful tool. Both of the small non-
rural units are equipped with wet scrubbers. Because existing medium 
units are predominantly equipped with wet scrubbers, the PM emission 
limit developed using the 99 percent UTL value of the data set for 
existing medium units also is being proposed for small non-rural units.
    A different methodology also was used for assessing performance of 
the six small rural HMIWI. To determine the actual performance of these 
small combustion-controlled units while considering the inherent 
variability in emissions, we obtained test data for all six units 
(although, as allowed in the emission guidelines, not all of the 
pollutants were tested at every unit) and selected as the emission 
limit the highest individual test run from the compliance testing for 
HCl, Pb, Cd, Hg, and CDD/CDF. This methodology uses actual test data to 
provide a reasonable estimate of the performance of the small rural 
units for these pollutants, where statistics are not a useful tool, 
while accounting for variability. There are exceptions to this 
methodology for CO, NOX, and SO2. As previously 
mentioned in this preamble, the CO, NOX, and SO2 
data for small rural units were combined with the CO, NOX, 
and SO2 data for the other subcategories of units. The 99 
percent UTL methodology was then used as the starting point, as 
previously described in this preamble, to determine proposed emission 
limits that would apply to all of the subcategories of existing HMIWI. 
Another exception to this methodology is the proposed emission limit 
for PM. As previously explained in this preamble, we are proposing a PM 
emission limit for existing small rural units based on the application 
of low-efficiency wet scrubbers to existing small non-rural units 
(i.e., we are proposing the same PM emission limit for small rural and 
non-rural units). While many of the resulting proposed emission limits 
for small rural units are significantly more stringent than the 1997 
promulgated limits, the proposed limits more accurately reflect the 
actual performance of these units.
    Finally, we examined the available data for calculating percent 
reduction requirements for HCl, Pb, Cd, and Hg. Percent reduction 
standards were included in the 1997 promulgated standards for these 
pollutants, and we are proposing to update these requirements to 
reflect the now-known actual performance of HMIWI utilizing MACT 
controls. For HCl, we obtained percent reduction data from five large 
HMIWI using dry scrubbers (i.e., the control technology upon which the 
emission limits for existing large, medium, and small non-rural units 
are based), and these data showed percent reductions from 94.2 percent 
to greater than 99 percent. To account for variability, we based the 
proposed percent reduction requirement of 94 percent on the lowest 
percent reduction recorded during the individual test runs (i.e., 94.2 
percent). The three-run test that included the 94.2 percent value 
showed significant variability and demonstrates the need to account for 
variability. The percent reduction values for the three runs ranged 
from 94.2 percent to 97.8 percent while there was no identifiable 
change in the operation of the unit or the dry scrubber. For Pb and Cd 
from existing large, medium, and small non-rural HMIWI, we used the 
same methodology as for HCl, and the data sets showed even greater 
variability. For Hg, we used the only available estimate of percent 
reduction. The proposed percent reduction standards are 71 percent for 
Pb, 74 percent for Cd, and 96 percent for Hg. The 5-year review 
methodology used to assess performance of existing HMIWI resulted in no 
change to the PM standards for existing large and medium units, and 
CDD/CDF standards for existing small rural units. All of the other 
standards for existing HMIWI were adjusted based on either the 5-year 
review or the remand analyses.
    Table 13 of this preamble summarizes the emission limits 
promulgated in 1997, the emission limits resulting from the proposed 
response to the Court remand, and the emission limits being proposed as 
a result of the 5-year review for existing HMIWI. Note that these 
proposed limits for existing HMIWI only apply to units for which 
construction was commenced on or before June 20,

[[Page 5535]]

1996, or for which modification was commenced before March 16, 1998.

 Table 13.--Summary of 1997 Promulgated Emission Limits, Proposed Remand Response Emission Limits, and Proposed 5-Year Review Limits for Existing HMIWI
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Proposed remand
         Pollutant  (units)                 Unit  size\1\        Promulgated  limit\2\     response limit\2\         Proposed 5-year review limit\2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
HCl (ppmv)..........................  L, M, S.................  100 or 93% reduction..  78 or 93% reduction...  51 or 94% reduction.
                                      SR......................  3,100.................  3,100.................  398
CO (ppmv)...........................  All.....................  40....................  40....................  25
Pb (mg/dscm)........................  L, M, S.................  1.2 or 70% reduction..  0.78 or 71% reduction.  0.64 or 71% reduction.
                                      SR......................  10....................  8.9...................  0.60
Cd (mg/dscm)........................  L, M, S.................  0.16 or 65% reduction.  0.11 or 66% reduction.  0.060 or 74% reduction.
                                      SR......................  4.....................  4.....................  0.050
Hg (mg/dscm)........................  L, M, S.................  0.55 or 85% reduction.  0.55 or 87% reduction.  0.33 or 96% reduction.
                                      SR......................  7.5...................  6.6...................  0.25
PM (gr/dscf)........................  L.......................  0.015.................  0.015.................  0.015
                                      M.......................  0.03..................  0.030.................  0.030
                                      S.......................  0.05..................  0.050.................  0.030
                                      SR......................  0.086.................  0.086.................  0.030
CDD/CDF, total (ng/dscm)............  L, M, S.................  125...................  115...................  115
                                      SR......................  800...................  800...................  800
CDD/CDF, TEQ (ng/dscm)..............  L, M, S.................  2.3...................  2.2...................  2.0
                                      SR......................  15....................  15....................  15
NOX (ppmv)..........................  All.....................  250...................  250...................  212
SO2 (ppmv)..........................  All.....................  55....................  55....................  28
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small; SR = Small Rural
\2\ All emission limits are measured at 7 percent oxygen.

    Table 14 of this preamble summarizes the emission limits 
promulgated in 1997 and the emission limits being proposed as a result 
of EPA's response to the Court remand for the 1997 NSPS HMIWI. Note 
that these proposed limits for 1997 NSPS HMIWI only apply to units for 
which construction was commenced after June 20, 1996, and on or before 
the date of this proposal, or for which modification is commenced 
before the date 6 months after promulgation of the proposed limits. 
Also note that where the proposed 5-year review limits for existing 
HMIWI are more stringent than those resulting from the remand response 
for 1997 NSPS HMIWI, the more stringent limits for existing HMIWI are 
included in the table as the limits being proposed. HMIWI subject to 
the 1997 NSPS, however, will not find these proposed limits, as 
presented in Table 14 of this preamble, in subparts Ec or Ce of 40 CFR 
part 60. Instead, they must consider the proposed revisions to subpart 
Ec of 40 CFR part 60 regarding existing HMIWI, as well as in the 
proposed revisions to subpart Ce of 40 CFR part 60 regarding 1997 NSPS 
HMIWI, and comply with the more stringent emission limit.

  Table 14.--Summary of 1997 Promulgated Emission Limits and Proposed Limits in Response to the Remand for 1997
                                                   NSPS HMIWI
----------------------------------------------------------------------------------------------------------------
                                                             Promulgated
       Pollutant (units)               Unit size\1\            limit\2\       Proposed remand response limit\2\
----------------------------------------------------------------------------------------------------------------
HCl (ppmv).....................  L, M, S................  15 or 99%          15 or 99% reduction.
                                                           reduction.
CO (ppmv)......................  L, M, S................  40...............  25 \3\.
Pb (mg/dscm)...................  L, M...................  0.07 or 98%        0.060 or 98% reduction.
                                                           reduction.
                                 S......................  1.2 or 70%         0.64 \3\ or 71% reduction.
                                                           reduction.
Cd (mg/dscm)...................  L, M...................  0.04 or 90%        0.030 or 93% reduction.
                                                           reduction.
                                 S......................  0.16 or 65%        0.060\3\ or 74% reduction \3\.
                                                           reduction.
Hg (mg/dscm)...................  L, M, S................  0.55 or 85%        0.33\3\ or 96% reduction \3\.
                                                           reduction.
PM (gr/dscf)...................  L, M...................  0.015............  0.0090
                                 S......................  0.03.............  0.018
CDD/CDF, total (ng/dscm).......  L, M...................  25...............  20
                                 S......................  125..............  111
CDD/CDF, TEQ (ng/dscm).........  L, M...................  0.6..............  0.53
                                 S......................  2.3..............  2.0 \3\.
NOX (ppmv).....................  L, M, S................  250..............  212 \3\.
SO2 (ppmv).....................  L, M, S................  55...............  28 \3\.
----------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small
\2\ All emission limits are measured at 7 percent oxygen.
\3\ Because the proposed 5-year review limit for existing HMIWI is more stringent than the one resulting from
  the remand response for 1997 NSPS HMIWI, the more stringent limit for existing HMIWI is being proposed.

    b. New Units. The first step in the analysis for new large and 
medium HMIWI was to assess the performance of the units currently 
operating a combined dry/wet control system, which is the control 
technology upon

[[Page 5536]]

which the 1997 NSPS for large and medium HMIWI was based. Four units 
currently are operating such controls, and we obtained compliance test 
data for each unit for use in assessing performance. We selected as the 
proposed emission limit the highest individual test run from the 
compliance testing for each pollutant. This methodology uses actual 
test data from the best-controlled sources in the industry to provide a 
reasonable estimate of the performance of these units, while accounting 
for variability. In several instances, the emission limit suggested by 
the highest run from the four combined-control sources was higher than 
either the emission limit for new sources that we are proposing in 
response to the Court remand or the 5-year review emission limit that 
we are proposing for existing sources. This was likely a result of the 
small amount of data that we used to establish the limits, and, in 
these instances, we are proposing the most stringent among these three 
limits for new sources.
    Although there are no small HMIWI subject to the current NSPS, we 
are proposing emission limits based on the performance of moderate-
efficiency wet scrubbers, which is the control technology upon which 
the 1997 limits for new small units was based. As an initial step in 
selection of these emission limits, we used the performance values 
representative of control with a moderate-efficiency wet scrubber as 
determined for the existing medium HMIWI. We then compared these values 
to the values for new small units developed in response to the remand 
and, in each case, we selected the more stringent value as the proposed 
emission limit.
    To determine proposed percent reduction requirements for new units 
for HCl, Pb, Cd, and Hg, we followed a methodology similar to that used 
for existing units. For HCl, we obtained percent reduction data from 
two units controlled with the MACT control technology for HCl for new 
large and medium units (wet scrubbers), and these data showed percent 
reductions greater than 99 percent. To account for variability, we 
based the percent reduction requirement of 99 percent on the lowest 
percent reduction recorded during the individual test runs (i.e., 99.1 
percent). We used the same methodology for each of the three metals for 
new large and medium units, and the corresponding percent reduction 
standards based on the MACT control technology (dry scrubbers) are 99 
percent for Pb, 99 percent for Cd, and 96 percent for Hg. For HCl from 
new small HMIWI, we used the same methodology as for new large and 
medium units because the MACT control technology upon which the 
reductions are based is the same (wet scrubbers). For Pb and Cd from 
new small HMIWI, we used the same methodology as for new large and 
medium units, except that the MACT control technology upon which the 
reductions are based is a wet scrubber. For Hg, we used the only 
available estimate of percent reduction. The proposed percent reduction 
standards for new small units are 99 percent for HCl, 71 percent for 
Pb, 74 percent for Cd, and 96 percent for Hg. The 5-year review 
methodology used to assess performance of new units resulted in no 
change to the HCl standards for all new units. All of the other 
standards for new units were adjusted based on either the 5-year review 
or the remand analyses.
    Table 15 of this preamble summarizes the emission limits 
promulgated in 1997 and the emission limits being proposed as a result 
of the 5-year review for new HMIWI. Note that these proposed limits for 
new HMIWI only apply to units for which construction is commenced after 
the date of this proposal, or for which modification is commenced on or 
after the date 6 months after promulgation of the proposed limits.

     Table 15.--Summary of 1997 Promulgated Emission Limits and Proposed 5-Year Review Limits for New HMIWI
----------------------------------------------------------------------------------------------------------------
                                                          Promulgated limit
       Pollutant  (units)             Unit size \1\              \2\           Proposed 5-year review limit \2\
----------------------------------------------------------------------------------------------------------------
HCl (ppmv).....................  L, M, S................  15 or 99%          15 or 99% reduction.
                                                           reduction.
CO (ppmv)......................  L, M, S................  40...............  25
Pb (mg/dscm)...................  L, M...................  0.07 or 98%        0.060 or 99% reduction.
                                                           reduction.
                                 S......................  1.2 or 70%         0.64 or 71% reduction.
                                                           reduction.
Cd (mg/dscm)...................  L, M...................  0.04 or 90%        0.0050 or 99% reduction.
                                                           reduction.
                                 S......................  0.16 or 65%        0.060 or 74% reduction.
                                                           reduction.
Hg (mg/dscm)...................  L, M...................  0.55 or 85%        0.19 or 96% reduction.
                                                           reduction.
                                 S......................  0.55 or 85%        0.33 or 96% reduction.
                                                           reduction.
PM (gr/dscf)...................  L, M...................  0.015............  0.0090
                                 S......................  0.03.............  0.018
CDD/CDF, total (ng/dscm).......  L, M...................  25...............  16
                                 S......................  125..............  111
CDD/CDF, TEQ (ng/dscm).........  L, M...................  0.6..............  0.21
                                 S......................  2.3..............  2.0
NOX (ppmv).....................  L, M, S................  250..............  212
SO2 (ppmv).....................  L, M...................  55...............  21
                                 S......................  55...............  28
----------------------------------------------------------------------------------------------------------------
\1\ L = Large; M = Medium; S = Small.
\2\ All emission limits are measured at 7 percent oxygen.

2. How did EPA determine the proposed performance testing and 
monitoring requirements?
    We are proposing minor adjustments to the performance testing and 
monitoring requirements that were promulgated in 1997. For existing 
HMIWI and 1997 NSPS HMIWI, we are proposing retaining the current 
requirements of the rule and adding the following requirements: Annual 
inspections of scrubbers and fabric filters; and one-time testing of 
the ash handling operations at the time of the next compliance test 
using EPA Method 22 of appendix A of 40 CFR part 60. These proposed 
requirements were selected to provide additional assurance that sources 
continue to operate at the levels established during their initial 
performance test. The proposed amendments would allow sources to use 
the results of previous emissions tests to demonstrate compliance with 
the

[[Page 5537]]

revised emission limits as long as the sources certify that the 
previous test results are representative of current operations. Only 
those sources whose previous emissions tests do not demonstrate 
compliance with one or more revised emission limits would be required 
to conduct another emissions test for those pollutants (note that 
sources are already required to test for HCl, CO, and PM on an annual 
basis).
    Additional requirements also are proposed for new HMIWI. For new 
sources, we are proposing retaining the current requirements and adding 
the following requirements: Use of CO CEMS; annual inspections of 
scrubbers and fabric filters; use of bag leak detection systems on 
fabric filter-based control systems; and annual testing of the ash 
handling operations using EPA Method 22 of appendix A of 40 CFR part 
60. For existing sources, in addition to the proposed changes in 
monitoring requirements, we also are proposing to allow for the 
optional use of bag leak detection systems. We also are clarifying that 
the rule allows for the following optional CEMS use: CO CEMS for 
existing sources and 1997 NSPS sources; and PM CEMS, HCl CEMS, multi-
metals CEMS, Hg CEMS, and semi-continuous dioxin monitoring for 
existing, 1997 NSPS, and new sources. The optional use of HCl CEMS, 
multi-metals CEMS, and semi-continuous dioxin monitoring will be 
available on the date a final performance specification for these 
monitoring systems is published in the Federal Register or the date of 
approval of a site-specific monitoring plan. The proposed testing and 
monitoring provisions are discussed below.
    a. Bag Leak Detection Systems. The proposed amendments would 
provide, as an alternative PM monitoring technique for existing sources 
and 1997 NSPS sources and a requirement for new sources, the use of bag 
leak detection systems on HMIWI controlled with fabric filters. Bag 
leak detection systems have been applied successfully at many 
industrial sources. EPA is proposing to drop the opacity testing 
requirements for HMIWI that use bag leak detection systems.
    b. CO CEMS. The proposed amendments would require the use of CO 
CEMS for new sources, and allow the use of CO CEMS on existing sources 
and 1997 NSPS sources. Owners and operators that use CO CEMS would be 
able to discontinue their annual CO compliance test as well as their 
monitoring of the secondary chamber temperature. The continuous 
monitoring of CO emissions is an effective way of ensuring that the 
combustion unit is operating properly. The proposed amendments 
incorporate the use of performance specification (PS)-4B 
(Specifications and Test Procedures for Carbon Monoxide and Oxygen 
Continuous Monitoring Systems in Stationary Sources) of appendix B of 
40 CFR part 60.
    The proposed CO emission limits are based on data from infrequent 
(normally annual) stack tests and compliance would be demonstrated by 
stack tests. The change to use of CO CEMS for measurement and 
enforcement of the same emission limits must be carefully considered in 
relation to an appropriate averaging period for data reduction. EPA 
considered this issue and concluded the use of a 24-hour block average 
was appropriate to address CO emissions variability, and EPA has 
included the use of a 24-hour block average in the proposed rule. The 
24-hour block average would be calculated following procedures in EPA 
Method 19 of appendix A of 40 CFR part 60. Facilities electing to use 
CO CEMS as an optional method would be required to notify EPA 1 month 
before starting use of CO CEMS and 1 month before stopping use of the 
CO CEMS. In addition, EPA specifically requests comment on whether 
continuous monitoring of CO emissions should be required for all 
existing HMIWI and all 1997 NSPS HMIWI.
    c. PM CEMS. The proposed amendments would allow the use of PM CEMS 
as an alternative testing and monitoring method. Owners or operators 
who choose to rely on PM CEMS would be able to discontinue their annual 
PM compliance test. In addition, because units that demonstrate 
compliance with the PM emission limits with a PM CEMS would clearly be 
meeting the opacity standard, compliance demonstration with PM CEMS 
would be considered a substitute for opacity testing. Owners and 
operators that use PM CEMS also would be able to discontinue their 
monitoring of minimum wet scrubber pressure drop, horsepower, or 
amperage. The proposed amendments incorporate the use of PS-11 
(Specifications and Test Procedures for Particulate Matter Continuous 
Emission Monitoring Systems at Stationary Sources) of appendix B of 40 
CFR part 60 for PM CEMS, and PS-11 QA Procedure 2 to ensure that PM 
CEMS are installed and operated properly and produce good quality 
monitoring data.
    The proposed PM emission limits are based on data from infrequent 
(normally annual) stack tests and compliance would be demonstrated by 
stack tests. The use of PM CEMS for measurement and enforcement of the 
same emission limits must be carefully considered in relation to an 
appropriate averaging period for data reduction. EPA considered this 
issue and concluded the use of a 24-hour block average was appropriate 
to address PM emissions variability, and EPA has included the use of a 
24-hour block average in the proposed rule. The 24-hour block average 
would be calculated following procedures in EPA Method 19 of appendix A 
of 40 CFR part 60. An owner or operator of an HMIWI unit who wishes to 
use PM CEMS would be required to notify EPA 1 month before starting use 
of PM CEMS and 1 month before stopping use of the PM CEMS.
    d. Other CEMS and Monitoring Systems. EPA also is proposing the 
optional use of HCl CEMS, multi-metals CEMS, Hg CEMS, and semi-
continuous dioxin monitoring as alternatives to the existing methods 
for demonstrating compliance with the HCl, metals (Pb, Cd, and Hg), and 
CDD/CDF emissions limits. For the reasons explained above for CO CEMS 
and PM CEMS, EPA has concluded that the use of 24-hour block averages 
would be appropriate to address emissions variability, and EPA has 
included the use of 24-hour block averages in the proposed rule. The 
24-hour block averages would be calculated following procedures in EPA 
Method 19 of appendix A of 40 CFR part 60. Although final performance 
specifications are not yet available for HCl CEMS and multi-metals 
CEMS, EPA is considering development of performance specifications. The 
proposed rule specifies that these options will be available to a 
facility on the date a final performance specification is published in 
the Federal Register or the date of approval of a site-specific 
monitoring plan.
    The use of HCl CEMS would allow the discontinuation of HCl sorbent 
flow rate monitoring, scrubber liquor pH monitoring, and the annual 
testing requirements for HCl. EPA has proposed PS-13 (Specifications 
and Test Procedures for Hydrochloric Acid Continuous Monitoring Systems 
in Stationary Sources) of appendix B of 40 CFR part 60 and believes 
that performance specification can serve as the basis for a performance 
specification for HCl CEMS use at HMIWI. In addition to the procedures 
used in proposed PS-13 for initial accuracy determination using the 
relative accuracy test, a comparison against a reference method, EPA is 
taking comment on an alternate initial accuracy determination 
procedure, similar to the one in section 11 of PS-15 (Performance 
Specification for

[[Page 5538]]

Extractive FTIR Continuous Emissions Monitor Systems in Stationary 
Sources) of appendix B of 40 CFR part 60 using the dynamic or analyte 
spiking procedure.
    EPA believes multi-metals CEMS can be used in many applications, 
including HMIWI. EPA has monitored side-by-side evaluations of multi-
metals CEMS with EPA Method 29 of appendix A of 40 CFR part 60 at 
industrial waste incinerators and found good correlation. EPA also 
approved the use of multi-metals CEMS as an alternative monitoring 
method at a hazardous waste combustor. EPA believes it is possible to 
adapt proposed PS-10 (Specifications and Test Procedures for Multi-
metals Continuous Monitoring Systems in Stationary Sources) of appendix 
B of 40 CFR part 60 or other EPA performance specifications to allow 
the use of multi-metals CEMS at HMIWI. In addition to the procedures 
used in proposed PS-10 for initial accuracy determination using the 
relative accuracy test, a comparison against a reference method, EPA is 
taking comment on an alternate initial accuracy determination 
procedure, similar to the one in section 11 of PS-15 using the dynamic 
or analyte spiking procedure.
    Relative to the use of Hg CEMS, EPA believes that PS-12A 
(Specifications and Test Procedures for Total Vapor Phase Mercury 
Continuous Emission Monitoring Systems in Stationary Sources) of 
appendix B of 40 CFR part 60 can provide the basis for using Hg CEMS at 
HMIWI. An owner or operator of an HMIWI unit who wishes to use Hg CEMS 
would be required to notify EPA 1 month before starting use of Hg CEMS 
and 1 month before stopping use of the Hg CEMS. The use of multi-metals 
CEMS or Hg CEMS would allow the discontinuation of wet scrubber outlet 
flue gas temperature monitoring. Mercury sorbent flow rate monitoring 
could not be eliminated in favor of a multi-metals CEMS or Hg CEMS 
because it also is an indicator of CDD/CDF control. Additionally, there 
is no annual metals test that could be eliminated.
    The semi-continuous monitoring of dioxin would entail use of a 
continuous automated sampling system and analysis of the sample using 
EPA Reference Method 23 of appendix A of 40 CFR part 60. The option to 
use a continuous automated sampling system would take effect on the 
date a final performance specification is published in the Federal 
Register or the date of approval of a site-specific monitoring plan. 
Semi-continuous monitoring of dioxin would allow the discontinuation of 
fabric filter inlet temperature monitoring. Dioxin/furan sorbent flow 
rate monitoring could not be eliminated in favor of semi-continuous 
monitoring of dioxin because it also is an indicator of Hg control. 
Additionally, there is no annual CDD/CDF test that could be eliminated. 
If semi-continuous monitoring of dioxin as well as multi-metals CEMS or 
Hg CEMS are used, Hg sorbent flow rate monitoring and CDD/CDF sorbent 
flow rate monitoring (in both cases activated carbon is the sorbent) 
could be eliminated. EPA requests comment on other parameter monitoring 
requirements that could be eliminated upon use of any or all of the 
optional CEMS discussed above. Table 16 of this preamble presents a 
summary of the HMIWI operating parameters, the pollutants influenced by 
each parameter, and alternative monitoring options for each parameter.

   Table 16.--Summary of HMIWI Operating Parameters, Pollutants Influenced by Each Parameter, and Alternative
                                      Monitoring Options for Each Parameter
----------------------------------------------------------------------------------------------------------------
                                Pollutants Influenced by Operating Parameter (by Control Device
     Operating parameter/                                    Type)                                 Alternative
    monitoring requirement    ------------------------------------------------------------------    monitoring
                                   Dry scrubber          Wet scrubber         Combined system        options
----------------------------------------------------------------------------------------------------------------
Maximum charge rate..........  All \1\.............  All \1\.............  All \1\.............  None.
Minimum secondary chamber      PM, CO, CDD/CDF.....  PM, CO, CDD/CDF.....  PM, CO, CDD/CDF.....  CO CEMS \2\.
 temperature.
Maximum fabric filter inlet    CDD/CDF.............  ....................  CDD/CDF.............  Semi-continuous
 temperature.                                                                                     dioxin
                                                                                                  monitoring
                                                                                                  system
                                                                                                  (SCDMS).
Minimum CDD/CDF sorbent flow   CDD/CDF.............  ....................  CDD/CDF.............  SCDMS and multi-
 rate.                                                                                            metals CEMS or
                                                                                                  Hg CEMS.
Minimum Hg sorbent flow rate.  Hg..................  ....................  Hg..................
Minimum HCl sorbent flow rate  HCl.................  ....................  HCl.................  HCl CEMS.
Minimum scrubber pressure      ....................  PM..................  PM..................  PM CEMS.
 drop/ horsepower amperage.
Minimum scrubber liquor flow   ....................  HCl, PM, Cd, Pb, Hg,  HCl, PM, Cd, Pb, Hg,  HCl CEMS, PM
 rate.                                                CDD/CDF.              CDD/CDF.              CEMS, multi-
                                                                                                  metals CEMS,
                                                                                                  and SCDMS.
Minimum scrubber liquor pH...  ....................  HCl.................  HCl.................  HCl CEMS.
Maximum flue gas temperature   ....................  Hg..................  ....................  Hg CEMS or
 (wet scrubber outlet).                                                                           multi-metals
                                                                                                  CEMS.
Do not use bypass stack        All \1\.............  All \1\.............  All \1\.............  None.
 (except during startup,
 shutdown, and malfunction).
Air pollution control device   All \1\.............  All \1\.............  All \1\.............  None.
 inspections.
----------------------------------------------------------------------------------------------------------------
\1\ ``All'' pollutants designation does not include SO2 and NOX, which are regulated at combustion-controlled
  levels (no add-on controls) and have no associated parameter monitoring.
\2\ Optional method for existing and 1997 NSPS sources; required for new sources.

    Table 17 of this preamble presents a summary of the HMIWI test 
methods and approved alternative compliance methods.

[[Page 5539]]

                    Table 17.--Summary of HMIWI Test Methods and Approved Alternative Methods
----------------------------------------------------------------------------------------------------------------
                                                                  Approved alternative
         Pollutant/parameter              Test method(s) \1\           method(s)                 Comments
----------------------------------------------------------------------------------------------------------------
PM...................................  Method 5, Method 29....  PM CEMS................  PM CEMS are optional
                                                                                          for all sources in
                                                                                          lieu of annual PM
                                                                                          test.
CO...................................  Method 10..............  CO CEMS................  CO CEMS are optional
                                                                                          for existing and 1997
                                                                                          NSPS sources in lieu
                                                                                          of annual CO test; CO
                                                                                          CEMS are required for
                                                                                          new sources.
HCl..................................  Method 26 or Method 26A  HCl CEMS...............  HCl CEMS are optional
                                                                                          for all sources in
                                                                                          lieu of annual HCl
                                                                                          test.
Cd...................................  Method 29..............  Multi-metals CEMS......
Pb...................................  Method 29..............  Multi-metals CEMS......
Hg...................................  Method 29..............  ASTM D6784-02, multi-
                                                                 metals CEMS or Hg CEMS.
CDD/CDF..............................  Method 23..............  Semi-continuous dioxin
                                                                 monitoring system.
Opacity..............................  Method 22..............  Bag leak detection       Bag leak detection
                                                                 system or PM CEMS.       systems are optional
                                                                                          for existing and 1997
                                                                                          NSPS sources; and are
                                                                                          required for new
                                                                                          sources.
Flue and exhaust gas analysis........  Method 3, 3A, or 3B....  ASME PTC 19-10-1981
                                                                 Part 10.
Opacity from ash handling............  Method 22..............  None...................
----------------------------------------------------------------------------------------------------------------
\1\ EPA Reference Methods in appendix A of 40 CFR part 60.

V. Impacts of the Proposed Action for Existing Units

    The emission limits for existing HMIWI that we are proposing as 
part of this action are based on the actual performance of the MACT 
control technologies. This proposed action is expected to result in 
modest improvements in performance being required by HMIWI that are not 
achieving the performance levels demonstrated in practice by the 
control technologies currently being used in the industry. Based on 
compliance test reports from all existing operating HMIWI (72 units at 
67 facilities) following MACT compliance in September 2002, 18 existing 
large HMIWI and 4 existing medium HMIWI are likely to find it necessary 
to improve performance of their units in order to achieve the proposed 
emission limits which their compliance test data indicates they would 
not meet. The modest improvements anticipated include adding lime (for 
SO2), increasing lime use (for HCl and SO2), 
increasing natural gas use (for CO and CDD/CDF), and increasing 
scrubber horsepower (for Pb, Cd, and Hg). Facilities may resubmit 
previous compliance test data that indicates that their HMIWI meets the 
proposed emission limits if the facility certifies that the test 
results are representative of current operations. Those facilities 
would then not be required to test for those pollutants to prove 
compliance with the emission limits.

A. What are the primary air impacts?

    As a result of the modest improvements estimated to be required at 
22 HMIWI such that they would achieve the proposed emission limits, EPA 
estimates that a total of approximately 24,700 pounds per year (lb/yr) 
of the regulated pollutants would be reduced. Approximate reductions by 
pollutant follow:
     HCl--20,600 lb/yr
     CO--400 lb/yr
     Pb--35 lb/yr
     Cd--3 lb/yr
     Hg--30 lb/yr
     PM--2,700 lb/yr
     CDD/CDF--0.0007 lb/yr
     NOX--200 lb/yr
     SO2--700 lb/yr

B. What are the water and solid waste impacts?

    EPA estimates that approximately 80 tpy of additional solid waste 
and 267,000 gallons per year of additional wastewater would be 
generated as a result of the increase of lime use by some facilities.

C. What are the energy impacts?

    EPA estimates that approximately 3,600 megawatt-hours per year of 
additional electricity would be required to support the increase in 
scrubber horsepower that we estimate would be required to enable some 
facilities to achieve the proposed emission limits.

D. What are the secondary air impacts?

    Secondary air impacts associated with this proposed action are 
direct impacts that result from the increase in natural gas use and/or 
wet scrubber horsepower that we estimate may be required to enable some 
facilities to achieve the proposed emission limits. We estimate that 
the adjustments could result in emissions of 211 lb/yr of PM; 1,880 lb/
yr of CO; 1,230 lb/yr of NOX; and 1,450 lb/yr of 
SO2 from the increased electricity and natural gas usage.

E. What are the cost and economic impacts?

    EPA estimates that the national total costs for the 72 existing 
HMIWI and 4 1997 NSPS HMIWI to comply with this proposed action would 
be approximately $488,000 in the first year of compliance. This 
estimate includes the costs that would be incurred by the 22 HMIWI that 
we anticipate needing to improve performance (i.e., costs of 
improvements in emissions control and emissions tests for pollutants 
for which the improvements are made), and the additional monitoring 
(i.e., annual control device inspections), testing (i.e. initial Method 
22 test), and recordkeeping and reporting costs that would be incurred 
by all 76 HMIWI as a result of this proposed action. Approximately 50 
percent of the estimated total cost in the first year is for emissions 
control, 11 percent is for monitoring, 32 percent is for testing, and 7 
percent is for recordkeeping and reporting. National total costs for 
subsequent years are estimated to be approximately $308,000 per year, 
with approximately 78 percent of the total cost for emissions control, 
18 percent for monitoring, and 3 percent for testing.
    Economic impact analyses focus on changes in market prices and 
output

[[Page 5540]]

levels. If changes in market prices and output levels in the primary 
markets are significant enough, impacts on other markets are also 
examined. EPA's economic impact analysis for this proposed action 
assessed the magnitude of the cost of market changes resulting from the 
proposed amendments by comparing annualized costs to annual sales. We 
were able to assess the cost of market changes for 70 HMIWI (sales 
information was unavailable for the other 6 units). For purposes of 
assessing economic impacts of the proposed action, the total annualized 
cost of this proposed action is estimated to be $328,000 and was 
determined by first annualizing at 7 percent over 15 years the 
difference between the first year costs and subsequent year costs for 
each of the 76 HMIWI, and adding to that value the subsequent year 
costs for each HMIWI; followed by then combining the annualized costs 
for the 76 HMIWI. The $328,000 was distributed among the 76 HMIWI, 
resulting in cost-to-sales ratios ranging from 0.0006 percent to 0.06 
percent, with an average cost-to-sales ratio of 0.003 percent. Because 
of the small size of these regulatory costs and estimated impacts, no 
additional market analysis is needed. Neither the modest national costs 
nor the facility level costs are anticipated to significantly impact 
any market.

VI. Impacts of the Proposed Action for New Units

    The current NSPS apply to HMIWI for which construction began after 
June 20, 1996, or for which modification began after March 16, 1998. 
There are three new HMIWI and one modified HMIWI that are subject to 
the current NSPS. No additional units have become subject to the NSPS 
since 2002. Considering this information, EPA does not anticipate any 
new HMIWI, and, therefore, no impacts of the proposed standards for new 
units. However, in the unlikely event that a new HMIWI is constructed, 
we are proposing new emission limits for those units based on 
performance of the control technology upon which current NSPS limits 
are based, as well as additional monitoring requirements, including use 
of CO CEMS and use of bag leak detection systems for fabric filters. 
Because EPA does not anticipate any new HMIWI, we, therefore, do not 
expect there to be any air impacts, water or solid waste impacts, 
energy impacts, or cost or economic impacts associated with the 
proposed standards for new sources.

VII. Relationship of the Proposed Action to Section 112(c)(6) of the 
CAA

    Section 112(c)(6) of the CAA requires EPA to identify categories of 
sources of seven specified pollutants to assure that sources accounting 
for not less than 90 percent of the aggregate emissions of each such 
pollutant are subject to standards under CAA section 112(d)(2) or 
112(d)(4). EPA has identified medical waste incinerators as a source 
category that emits five of the seven CAA section 112(c)(6) pollutants: 
Polycyclic organic matter (POM), dioxins, furans, Hg, and 
polychlorinated biphenyls (PCBs). (The POM emitted by HMIWI is composed 
of 16 polyaromatic hydrocarbons (PAH) and extractable organic matter 
(EOM).) In the Federal Register notice Source Category Listing for 
Section 112(d)(2) Rulemaking Pursuant to Section 112(c)(6) 
Requirements, 63 FR 17838, 17849, Table 2 (1998), EPA identified 
medical waste incinerators (now referred to as HMIWI) as a source 
category ``subject to regulation'' for purposes of CAA section 
112(c)(6) with respect to the CAA section 112(c)(6) pollutants that 
HMIWI emit. HMIWI are solid waste incineration units currently 
regulated under CAA section 129. For purposes of CAA section 112(c)(6), 
EPA has determined that standards promulgated under CAA section 129 are 
substantively equivalent to those promulgated under CAA section 112(d). 
(See Id. at 17845; see also 62 FR 33625, 33632 (1997).) As discussed in 
more detail below, the CAA section 129 standards effectively control 
emissions of the five identified CAA section 112(c)(6) pollutants. 
Further, since CAA section 129(h)(2) precludes EPA from regulating 
these substantial sources of the five identified CAA section 112(c)(6) 
pollutants under CAA section 112(d), EPA cannot further regulate these 
emissions under that CAA section. As a result, EPA considers emissions 
of these five pollutants from HMIWI units ``subject to standards'' for 
purposes of CAA section 112(c)(6).
    As required by the statute, the CAA section 129 HMIWI standards 
include numeric emission limitations for the nine pollutants specified 
in that section. The combination of good combustion practices and add-
on air pollution control equipment (dry sorbent injection fabric 
filters, wet scrubbers, or combined fabric filter and wet scrubber 
systems) effectively reduces emissions of the pollutants for which 
emission limits are required under CAA section 129: Hg, CDD/CDF, Cd, 
Pb, PM, SO2, HCl, CO, and NOX. Thus, the NSPS and 
emissions guidelines specifically require reduction in emissions of 
three of the CAA section 112(c)(6) pollutants: Dioxins, furans, and Hg. 
As explained below, the air pollution controls necessary to comply with 
the requirements of the HMIWI NSPS and emission guidelines also 
effectively reduce emissions of the following CAA section 112(c)(6) 
pollutants that are emitted from HMIWI units: POM and PCBs. Although 
the CAA section 129 HMIWI standards do not have separate, specific 
emissions standards for PCBs and POM, emissions of these two CAA 
section 112(c)(6) pollutants are effectively controlled by the same 
control measures used to comply with the numerical emissions limits for 
the enumerated CAA section 129 pollutants. Specifically, as byproducts 
of combustion, the formation of PCBs and POM is effectively reduced by 
the combustion and post-combustion practices required to comply with 
the CAA section 129 standards. Any PCBs and POM that do form during 
combustion are further controlled by the various post-combustion HMIWI 
controls. The add-on PM control systems (either fabric filter or wet 
scrubber) and activated carbon injection in the fabric filter-based 
systems further reduce emissions of these organic pollutants, as well 
as reducing Hg emissions. The post-MACT compliance tests at currently 
operating HMIWI show that the HMIWI MACT regulations reduced Hg 
emissions by greater than 80 percent and CDD/CDF emissions by about 90 
percent from pre-MACT levels. In light of the fact that similar 
controls have been demonstrated to effectively reduce emissions of POM 
and PCBs from another incineration source category (municipal solid 
waste combustors), it is, therefore, reasonable to conclude that POM 
and PCB emissions are substantially reduced at all 76 HMIWI. Thus, 
while the proposed rule does not identify specific limits for POM and 
PCB, they are, for the reasons noted above, nonetheless ``subject to 
regulation'' for purposes of section 112(c)(6) of the CAA.

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735; October 4, 1993), this 
proposed action is a ``significant regulatory action'' because it is 
likely to raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order. Accordingly, EPA submitted this proposed action to 
the Office of Management and Budget (OMB) for

[[Page 5541]]

review under Executive Order 12866, and any changes made in response to 
OMB recommendations have been documented in the docket for this action.

B. Paperwork Reduction Act

    The information collection requirements associated with this 
proposed action are included in the information collection requirements 
addressing the HMIWI standards in their entirety, which have been 
submitted for approval to the OMB under the Paperwork Reduction Act, 44 
U.S.C. 3501 et seq. The Information Collection Request (ICR) documents 
prepared by EPA have been assigned EPA ICR number 1899.04 for subpart 
Ce and 1730.05 for subpart Ec.
    The requirements in this proposed action result in industry 
recordkeeping and reporting burden associated with review of the 
amendments for all HMIWI, initial EPA Method 22 testing for all HMIWI, 
annual inspections of scrubbers and fabric filters for all HMIWI, and 
stack testing and development of new parameter limits for HMIWI that 
need to make performance improvements. The total nationwide 
recordkeeping and reporting burden of this proposed action is estimated 
at 722 hours at a cost of approximately $32,800. This burden and cost 
would only be applicable once. After that, the total nationwide 
recordkeeping and reporting burden and costs would be $0 (above and 
beyond current burden and costs).
    The annual average burden associated with the emission guidelines 
over the first 3 years following promulgation of this proposed action 
is estimated to be 49,878 hours at a total annual labor cost of 
$2,433,045. The total annualized capital/startup costs and operation 
and maintenance (O&M) costs associated with the monitoring 
requirements, EPA Method 22 testing, storage of data and reports, and 
photocopying and postage over the 3-year period of the ICR are 
estimated at $407,953 and $333,258 per year, respectively. (The annual 
inspection costs are included under the recordkeeping and reporting 
labor costs.) The annual average burden associated with the NSPS over 
the first 3 years following promulgation of this proposed action is 
estimated to be 2,004 hours at a total annual labor cost of $91,011. 
The total annualized capital/startup costs are estimated at $13,046, 
with total operation and maintenance costs of $36,310 per year.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    An Agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations are listed in 40 CFR part 9.
    To comment on the Agency's need for this information, the accuracy 
of the provided burden estimates, and any suggested methods for 
minimizing respondent burden, including the use of automated collection 
techniques, EPA has established a public docket for this action, which 
includes these ICR documents, under Docket ID No. EPA-HQ-OAR-2006-0534. 
Submit any comments related to the ICR documents for this proposed 
action to EPA and OMB. See ADDRESSES section at the beginning of this 
notice for where to submit comments to EPA. Send comments to OMB at the 
Office of Information and Regulatory Affairs, Office of Management and 
Budget, 725 17th Street, NW., Washington, DC 20503, Attention: Desk 
Office for EPA. Since OMB is required to make a decision concerning the 
ICR between 30 and 60 days after February 6, 2007, a comment to OMB is 
best assured of having its full effect if OMB receives it by March 8, 
2007. The final action will respond to any OMB or public comments on 
the information collection requirements contained in this proposal.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to prepare a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements under the Administrative 
Procedures Act or any other statute unless the agency certifies that 
the proposed action will not have a significant economic impact on a 
substantial number of small entities. Small entities include small 
businesses, small government organizations, and small government 
jurisdictions.
    For purposes of assessing the impacts of this proposed action on 
small entities, small entity is defined as follows: (1) A small 
business as defined by the Small Business Administration's (SBA) 
regulations at 13 CFR 121.201; (2) a small governmental jurisdiction 
that is a government of a city, county, town, school district or 
special district with a population of less than 50,000; or (3) a small 
organization that is any not-for-profit enterprise that is 
independently owned and operated and is not dominant in its field.
    After considering the economic impacts of this proposed action on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. Because none 
of the HMIWI facilities are expected to be significantly impacted by 
this proposed action, that also means that none of the four small 
entity-owned facilities would be expected to be significantly impacted. 
None of the 22 HMIWI that we estimate would need to make improvements 
in order to meet the proposed emission limits are owned by small 
entities. The only estimated economic impacts on small entities would 
result from the additional monitoring requirements (annual control 
device inspections), testing requirements (one-time EPA Method 22 
testing), and associated recordkeeping and reporting requirements of 
this proposed action.
    We continue to be interested in the potential impacts of this 
proposed action on small entities and welcome comments on issues 
related to such impacts.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act (UMRA) of 1995, Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and Tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures by State, local, and Tribal governments, in 
the aggregate, or by the private sector, of $100 million or more in any 
1 year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective, or least burdensome alternative 
that achieves the objectives of the proposed rule. The provisions of 
section 205 do not apply when they are inconsistent with applicable 
law. Moreover, section 205 allows EPA to

[[Page 5542]]

adopt an alternative other than the least costly, most cost-effective, 
or least burdensome alternative if EPA publishes with the final rule an 
explanation why that alternative was not adopted.
    Before EPA establishes any regulatory requirements that may 
significantly or uniquely affect small governments, including Tribal 
governments, EPA must develop a small government agency plan under 
section 203 of the UMRA. The plan must provide for notifying 
potentially affected small governments, enabling officials of affected 
small governments to have meaningful and timely input in the 
development of EPA's regulatory proposals with significant Federal 
intergovernmental mandates, and informing, educating, and advising 
small governments on compliance with the regulatory requirements.
    EPA has determined that this proposed action does not contain a 
Federal mandate that may result in expenditures of $100 million or more 
for State, local, and Tribal governments, in the aggregate, or the 
private sector in any 1 year. Thus, this proposed action is not subject 
to the requirements of section 202 and 205 of the UMRA. In addition, 
EPA has determined that this proposed action contains no regulatory 
requirements that might significantly or uniquely affect small 
governments. Therefore, this proposed action is not subject to the 
requirements of section 203 of the UMRA.

E. Executive Order 13132: Federalism

    Executive Order 13132 (64 FR 43255; August 10, 1999), requires EPA 
to develop an accountable process to ensure ``meaningful and timely 
input by State and local officials in the development of regulatory 
policies that have federalism implications.'' ``Policies that have 
federalism implications'' are defined in the Executive Order to include 
regulations that have ``substantial direct effects on the States, on 
the relationship between the national government and the States, or on 
the distribution of power and responsibilities among the various levels 
of government.'' This proposed action does not have federalism 
implications. It will not have substantial direct effects on the 
States, on the relationship between the national government and the 
States, or on the distribution of power and responsibilities among the 
various levels of government, as specified in Executive Order 13132. 
This proposed action will not impose substantial direct compliance 
costs on State or local governments, and will not preempt State law. 
Thus, Executive Order 13132 does not apply to this proposed action.
    In the spirit of Executive Order 13132, and consistent with EPA 
policy to promote communications between EPA and State and local 
governments, EPA specifically solicits comment on this proposed action 
from State and local officials.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175, (65 FR 67249; November 9, 2000), requires 
EPA to develop an accountable process to ensure ``meaningful and timely 
input by Tribal officials in the development of regulatory policies 
that have Tribal implications.''
    This proposed action does not have Tribal implications, as 
specified in Executive Order 13175. It will not have substantial direct 
effects on Tribal governments, on the relationship between the Federal 
government and Indian tribes, or on the distribution of power and 
responsibilities between the Federal government and Indian tribes, as 
specified in Executive Order 13175. EPA is not aware of any HMIWI owned 
or operated by Indian Tribal governments. Thus, Executive Order 13175 
does not apply to this proposed action.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    Executive Order 13045 (62 FR 19885; April 23, 1997), applies to any 
rule that: (1) Is determined to be ``economically significant'' as 
defined under Executive Order 12866, and (2) concerns an environmental 
health or safety risk that EPA has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, EPA must evaluate the environmental health or safety 
effects of the planned rule on children, and explain why the planned 
regulation is preferable to other potentially effective and reasonably 
feasible alternatives EPA considered.
    EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that are based on health or safety risks, such that 
the analysis required under section 5-501 of the Executive Order has 
the potential to influence the regulation. This proposed action is not 
subject to Executive Order 13045 because it is based on technology 
performance and not on health and safety risks.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution or Use

    This proposed action is not a ``significant energy action'' as 
defined in Executive Order 13211, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 
28355; May 22, 2001) because it is not likely to have a significant 
adverse effect on the supply, distribution, or use of energy. EPA 
estimates that the requirements in this proposed action would cause 
some HMIWI to increase the horsepower of their wet scrubbers, resulting 
in approximately 3,600 megawatt-hours per year of additional 
electricity being used.
    Given the negligible change in energy consumption resulting from 
this proposed action, EPA does not expect any price increase for any 
energy type. The cost of energy distribution should not be affected by 
this proposed action at all since the action would not affect energy 
distribution facilities. We also expect that there would be no impact 
on the import of foreign energy supplies, and no other adverse outcomes 
are expected to occur with regard to energy supplies.

I. National Technology Transfer Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act (NTTAA) of 1995 (Pub. L. 104-113, Section 12(d), 15 U.S.C. 272 
note) directs EPA to use voluntary consensus standards (VCS) in its 
regulatory activities, unless to do so would be inconsistent with 
applicable law or otherwise impractical. The VCS are technical 
standards (e.g., materials specifications, test methods, sampling 
procedures, and business practices) that are developed or adopted by 
VCS bodies. The NTTAA directs EPA to provide Congress, through OMB, 
explanations when the Agency does not use available and applicable VCS.
    This proposed action involves technical standards. EPA cites the 
following standards: EPA Methods 1, 3, 3A, 3B, 5, 9, 10, 10B, 22, 23, 
26, 26A, and 29 in 40 CFR part 60, appendix A. Consistent with the 
NTTAA, EPA conducted searches to identify voluntary consensus standards 
in addition to these EPA methods. No applicable voluntary consensus 
standards were identified for EPA Methods 9 and 22. The search and 
review results are in the docket for this proposed action.
    Two voluntary consensus standards were identified as acceptable

[[Page 5543]]

alternatives to EPA test methods for the purposes of this proposed 
action. The voluntary consensus standard ASME PTC 19-10-1981-Part 10, 
``Flue and Exhaust Gas Analyses,'' is cited in the proposed action for 
its manual method for measuring the oxygen content of exhaust gas. This 
part of ASME PTC 19-10-1981-Part 10 is an acceptable alternative to EPA 
Method 3B.
    The voluntary consensus standard ASTM D6784-02, ``Standard Test 
Method for Elemental, Oxidized, Particle-Bound and Total Mercury Gas 
Generated from Coal-Fired Stationary Sources (Ontario Hydro Method),'' 
is an acceptable alternative to EPA Method 29 (portion for mercury 
only) as a method for measuring Hg.
    The search for emissions measurement procedures identified 16 other 
voluntary consensus standards. EPA determined that these 16 standards 
identified for measuring emissions of the pollutants subject to 
emission standards in this proposed action were impractical 
alternatives to EPA test methods for the purposes of this action. 
Therefore, EPA does not intend to adopt these standards for this 
purpose. A document that discusses the determinations for these 16 
methods is located in the docket to this proposed action.
    Section 60.56c of subpart Ec of 40 CFR part 60 and Sec.  60.37e of 
subpart Ce of 40 CFR part 60 list the testing methods included in the 
proposed action. Under 40 CFR 60.8(b) and 60.13(i) of subpart A 
(General Provisions), a source may apply to EPA for permission to use 
alternative test methods or alternative monitoring requirements in 
place of any required testing methods, performance specifications, or 
procedures.

List of Subjects in 40 CFR Part 60

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Intergovernmental relations, Reporting and 
recordkeeping requirements.

    Dated: January 26, 2007.
Stephen L. Johnson,
Administrator.
    For the reasons stated in the preamble, title 40, chapter I, part 
60 of the Code of Federal Regulations is proposed to be amended as 
follows:

PART 60--[AMENDED]

    1. The authority citation for part 60 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.

Subpart Ce--[Amended]

    2. Section 60.32e is amended by revising paragraphs (a) and (i) to 
read as follows:

Sec.  60.32e  Designated facilities.

    (a) Except as provided in paragraphs (b) through (h) of this 
section, the designated facility to which the guidelines apply is each 
individual HMIWI for which construction was commenced on or before June 
20, 1996 and each individual HMIWI currently subject to subpart Ec as 
promulgated in 1997 (for which construction was commenced after June 
20, 1996 but no later than February 6, 2007 or for which modification 
commenced after March 16, 1998 but no later than 6 months after the 
date of promulgation of this subpart).
* * * * *
    (i) Beginning 3 years after the date of promulgation of this 
subpart, or on the effective date of an EPA approved operating permit 
program under Clean Air Act title V and the implementing regulations 
under 40 CFR part 70 in the State in which the unit is located, 
whichever date is later, designated facilities subject to this subpart 
shall operate pursuant to a permit issued under the EPA-approved 
operating permit program.
    3. Section 60.33e is amended by revising paragraph (b) to read as 
follows:

Sec.  60.33e  Emission guidelines.

* * * * *
    (b) For approval, a State plan shall include the requirements for 
emission limits at least as protective as those requirements listed in 
Table 2 of this subpart for any small HMIWI constructed on or before 
June 20, 1996 which is located more than 50 miles from the boundary of 
the nearest Standard Metropolitan Statistical Area (defined in Sec.  
60.31e) and which burns less than 2,000 pounds per week of hospital 
waste and medical/infectious waste. The 2,000 lb/week limitation does 
not apply during performance tests.
* * * * *
    4. Section 60.36e is amended by adding paragraphs (c) and (d) to 
read as follows:

Sec.  60.36e  Inspection guidelines.

* * * * *
    (c) For approval, a State plan shall require that each HMIWI 
subject to the emission limits under Sec.  60.33e(a) undergo an initial 
air pollution control device inspection that is at least as protective 
as the following within 1 year following approval of the State plan:
    (1) At a minimum, an inspection shall include the following:
    (i) Inspect air pollution control device(s) for proper operation, 
if applicable;
    (ii) Ensure proper calibration of thermocouples, sorbent feed 
systems, and any other monitoring equipment; and
    (iii) Generally observe that the equipment is maintained in good 
operating condition.
    (2) Within 10 operating days following an air pollution control 
device inspection, all necessary repairs shall be completed unless the 
owner or operator obtains written approval from the State agency 
establishing a date whereby all necessary repairs of the designated 
facility shall be completed.
    (d) For approval, a State plan shall require that each HMIWI 
subject to the emission limits under Sec.  60.33e(a) undergo an air 
pollution control device inspection annually (no more than 12 months 
following the previous annual air pollution control device inspection), 
as outlined in paragraphs (c)(1) and (2) of this section.
    5. Section 60.37e is amended by revising paragraphs (a) and (b)(1) 
and adding paragraph (e) to read as follows:

Sec.  60.37e  Compliance, performance testing, and monitoring 
guidelines.

    (a) Except as provided in paragraph (b) of this section, for 
approval, a State plan shall include the requirements for compliance 
and performance testing listed in Sec.  60.56c of subpart Ec of this 
part, excluding the fugitive emissions annual testing requirement under 
Sec.  60.56c(c)(3), the CO CEMS requirements under Sec.  60.56c(c)(5), 
and the bag leak detection system requirements under Sec.  60.57c(g). 
Sources may, however, elect to use CO CEMS as specified under Sec.  
60.56c(c)(5) or bag leak detection systems as specified under Sec.  
60.57c(g).
    (b) * * *
    (1) Conduct the performance testing requirements in Sec.  
60.56c(a), (b)(1) through (b)(9), (b)(11) (Hg only), (b)(12), and 
(c)(1) of subpart Ec of this part. The 2,000 lb/week limitation under 
Sec.  60.33e(b) does not apply during performance tests.
* * * * *
    (e) The owner or operator of a designated facility may use the 
results of previous emissions tests to demonstrate compliance with the 
emission limits, provided that the conditions in paragraphs (e)(1) 
through (e)(3) of this section are met:
    (1) The previous emissions tests must have been conducted using the 
applicable procedures and test methods

[[Page 5544]]

listed in Sec.  60.56c(b)(1) through (b)(9), (b)(11) (Hg only), and 
(b)(12). Previous emissions test results obtained using EPA-accepted 
voluntary consensus standards are also acceptable.
    (2) The HMIWI at the affected facility shall be operated in a 
manner (e.g., with charge rate, secondary chamber temperature, etc.) 
that would be expected to result in the same or lower emissions than 
observed during the previous emissions test(s), and the HMIWI may not 
have been modified such that emissions would be expected to exceed 
(notwithstanding normal test-to-test variability) the results from 
previous emissions test(s).
    (3) The previous emissions test(s) must have been conducted in 1997 
or later.
    6. Section 60.38e is amended by revising paragraph (a) and adding 
paragraph (c) to read as follows:

Sec.  60.38e  Reporting and recordkeeping guidelines.

    (a) For approval, a State plan shall include the reporting and 
recordkeeping requirements listed in Sec.  60.58c(b), (c), (d), (e), 
and (f) of subpart Ec of this part, excluding Sec.  60.58c(b)(7) 
(siting).
* * * * *
    (c) For approval, a State plan shall require the owner or operator 
of each HMIWI subject to the emission limits under Sec.  60.33e(a) to:
    (1) Maintain records of the annual air pollution control device 
inspections, any required maintenance, and any repairs not completed 
within 10 days of an inspection or the timeframe established by the 
State regulatory agency; and
    (2) Submit an annual report containing information recorded under 
paragraph (c)(1) of this section no later than 60 days following the 
year in which data were collected. Subsequent reports shall be sent no 
later than 12 calendar months following the previous report (once the 
unit is subject to permitting requirements under title V of the Act, 
the owner or operator shall submit these reports semiannually). The 
report shall be signed by the facilities manager.
    7. Section 60.39e is amended as follows:
    a. By revising paragraph (a);
    b. By revising paragraph (c) introductory text;
    c. By revising paragraph (d)(3); and
    d. By revising paragraph (f).

Sec.  60.39e  Compliance times.

    (a) Not later than 1 year after the date of promulgation of this 
subpart, each State in which a designated facility is operating shall 
submit to the Administrator a plan to implement and enforce the 
emission guidelines.
* * * * *
    (c) State plans that specify measurable and enforceable incremental 
steps of progress towards compliance for designated facilities planning 
to install the necessary air pollution control equipment may allow 
compliance on or before the date 3 years after EPA approval of the 
State plan (but not later than 5 years after the date of promulgation 
of this subpart). Suggested measurable and enforceable activities to be 
included in State plans are:
* * * * *
    (d) * * *
    (3) If an extension is granted, require compliance with the 
emission guidelines on or before the date 3 years after EPA approval of 
the State plan (but not later than 5 years after the date of 
promulgation of this subpart).
* * * * *
    (f) The Administrator shall develop, implement, and enforce a plan 
for existing HMIWI located in any State that has not submitted an 
approvable plan within 2 years after the date of promulgation of this 
subpart. Such plans shall ensure that each designated facility is in 
compliance with the provisions of this subpart no later than 5 years 
after the date of promulgation of this subpart.
    8. Table 1 to subpart Ce is revised to read as follows:

                   Table 1 to Subpart Ce.--Emission Limits for Small, Medium, and Large HMIWI
----------------------------------------------------------------------------------------------------------------
                                                                        Emission limits HMIWI size
           Pollutant                Units (7 percent    --------------------------------------------------------
                                   oxygen, dry basis)          Small              Medium             Large
----------------------------------------------------------------------------------------------------------------
Particulate matter.............  Milligrams per dry      69 (0.030).......  69 (0.030).......  34 (0.015).
                                  standard cubic meter
                                  (mg/dscm) (grains per
                                  dry standard cubic
                                  foot (gr/dscf)).
Carbon monoxide................  Parts per million by    25...............  25...............  25.
                                  volume (ppmv).
Dioxins/furans.................  Nanograms per dry       115 (50) or 2.0    115 (50) or 2.0    115 (50) or 2.0
                                  standard cubic meter    (0.87).            (0.87).            (0.87).
                                  total dioxins/furans
                                  (ng/dscm) (grains per
                                  billion dry standard
                                  cubic feet (gr/10\9\
                                  dscf)) or ng/dscm TEQ
                                  (gr/10\9\ dscf).
Hydrogen chloride..............  ppmv or percent         51 or 94%........  51 or 94%........  51 or 94%
                                  reduction.
Sulfur dioxide.................  Ppmv..................  28...............  28...............  28.
Nitrogen oxides................  Ppmv..................  212..............  212..............  212.
Lead...........................  mg/dscm (grains per     0.64 (0.28) or     0.64 (0.28) or     0.64 (0.28) or
                                  thousand dry standard   71%.               71%.               71%.
                                  cubic feet (gr/10\3\
                                  dscf)) or percent
                                  reduction.
Cadmium........................  mg/dscm (gr/10\3\       0.060 (0.026) or   0.060 (0.026) or   0.060 (0.026) or
                                  dscf) or percent        74%.               74%.               74%.
                                  reduction.
Mercury........................  mg/dscm (gr/10\3\       0.33 (0.14) or     0.33 (0.14) or     0.33 (0.14) or
                                  dscf) or percent        96%.               96%.               96%.
                                  reduction.
----------------------------------------------------------------------------------------------------------------

    9. Table 2 of subpart Ce is revised to read as follows:

     Table 2 to Subpart Ce.--Emission Limits for Small HMIWI Which Meet the Criteria Under Sec.   60.33E(B)
----------------------------------------------------------------------------------------------------------------
                                         Units (7 percent oxygen, dry
               Pollutant                            basis)                        HMIWI emission limits
----------------------------------------------------------------------------------------------------------------
Particulate matter....................  mg/dscm (gr/dscf).............  69 (0.030).
Carbon monoxide.......................  Ppmv..........................  25.

[[Page 5545]]

Dioxins/furans........................  ng/dscm total dioxins/furans    800 (350) or 15 (6.6).
                                         (gr/10\9\ dscf) or ng/dscm
                                         TEQ (gr/10\9\ dscf).
Hydrogen chloride.....................  ppmv or percent reduction.....  398.
Sulfur dioxide........................  Ppmv..........................  28.
Nitrogen oxides.......................  Ppmv..........................  212.
Lead..................................  mg/dscm (gr/10\3\ dscf) or      0.60 (0.26).
                                         percent reduction.
Cadmium...............................  mg/dscm (gr/10\3\ dscf) or      0.050 (0.022).
                                         percent reduction.
Mercury...............................  mg/dscm (gr/10\3\ dscf) or      0.25 (0.11).
                                         percent reduction.
----------------------------------------------------------------------------------------------------------------

Subpart Ec--[Amended]

    10. Section 60.50c is amended by revising paragraphs (a), (k) and 
(l) to read as follows:

Sec.  60.50c  Applicability and delegation of authority.

    (a) Except as provided in paragraphs (b) through (h) of this 
section, the affected facility to which this subpart applies is each 
individual hospital/medical/infectious waste incinerator (HMIWI):
    (1) For which construction is commenced after June 20, 1996 but no 
later than February 6, 2007;
    (2) For which modification is commenced after March 16, 1998 but no 
later than 6 months after the date of promulgation of this subpart;
    (3) For which construction is commenced after February 6, 2007; or
    (4) For which modification is commenced after 6 months after the 
date of promulgation of this subpart.
* * * * *
    (k) The requirements of this subpart shall become effective 6 
months after the date of promulgation of this subpart.
    (l) Beginning 3 years after the date of promulgation of this 
subpart, or on the effective date of an EPA-approved operating permit 
program under Clean Air Act title V and the implementing regulations 
under 40 CFR part 70 in the State in which the unit is located, 
whichever date is later, affected facilities subject to this subpart 
shall operate pursuant to a permit issued under the EPA approved State 
operating permit program.
    11. Section 60.51c is amended by adding a definition for ``Bag leak 
detection system'' in alphabetical order and revising the definition 
for ``Minimum secondary chamber temperature'' to read as follows:

Sec.  60.51c  Definitions.

    Bag leak detection system means an instrument that is capable of 
monitoring PM loadings in the exhaust of a fabric filter in order to 
detect bag failures. A bag leak detection system includes, but is not 
limited to, an instrument that operates on triboelectric, light-
scattering, light-transmittance, or other effects to monitor relative 
PM loadings.
* * * * *
    Minimum secondary chamber temperature means 90 percent of the 
highest 3-hour average secondary chamber temperature (taken, at a 
minimum, once every minute) measured during the most recent performance 
test demonstrating compliance with the PM, CO, and dioxin/furan 
emission limits.
* * * * *
    12. Section 60.52c is amended by revising paragraph (c) to read as 
follows:

Sec.  60.52c  Emission limits.

* * * * *
    (c) On and after the date on which the initial performance test is 
completed or is required to be completed under Sec.  60.8, whichever 
date comes first, no owner or operator of an affected facility shall 
cause to be discharged into the atmosphere visible emissions of 
combustion ash from an ash conveying system (including conveyor 
transfer points) in excess of 5 percent of the observation period 
(i.e., 9 minutes per 3-hour period), as determined by EPA Reference 
Method 22 of appendix A of this part, except as provided in paragraphs 
(d) and (e) of this section.
* * * * *
    13. Section 60.56c is amended as follows:
    a. By revising paragraph (b) introductory text;
    b. By revising paragraphs (b)(4) and (b)(6) through (b)(8), (b)(9) 
introductory text, and (b)(10);
    c. By revising paragraph (b)(11);
    d. By revising paragraphs (c)(2) through (4);
    e. By adding paragraphs (c)(5), and (c)(6);
    f. By revising paragraph (d) introductory text;
    g. By adding paragraphs (e)(6) and (7);
    h. By adding paragraphs (f)(7) through (9);
    i. By adding paragraphs (g)(6) through (9); and
    j. By adding paragraph (k).

Sec.  60.56c  Compliance and performance testing.

* * * * *
    (b) Except as provided in paragraph (k) of this section, the owner 
or operator of an affected facility shall conduct an initial 
performance test as required under Sec.  60.8 to determine compliance 
with the emission limits using the procedures and test methods listed 
in paragraphs (b)(1) through (b)(12) of this section. The use of the 
bypass stack during a performance test shall invalidate the performance 
test.
* * * * *
    (4) EPA Reference Method 3, 3A, or 3B of appendix A of this part 
shall be used for gas composition analysis, including measurement of 
oxygen concentration. EPA Reference Method 3, 3A, or 3B of appendix A 
of this part shall be used simultaneously with each of the other EPA 
reference methods. As an alternative, ASME PTC-19-10-1981-Part 10 may 
be used.
* * * * *
    (6) EPA Reference Method 5 or 29 of appendix A of this part shall 
be used to measure the particulate matter emissions. As an alternative, 
PM CEMS may be used as specified in paragraph (c)(4) of this section.
    (7) EPA Reference Method 9 of appendix A of this part shall be used 
to measure stack opacity. As an alternative, demonstration of 
compliance with the PM standards using bag leak detection systems as 
specified in Sec.  60.57c(g) or PM CEMS as specified in paragraph 
(c)(4) of this section is considered demonstrative of compliance with 
the opacity requirements.
    (8) For affected facilities under Sec.  60.50c(a)(1) and (a)(2), 
EPA Reference Method 10 or 10B of appendix A of this part shall be used 
to measure the CO emissions. As an alternative, CO CEMS may be used as 
specified in paragraph (c)(4) of this section.
    (9) EPA Reference Method 23 of appendix A of this part shall be 
used to

[[Page 5546]]

measure total dioxin/furan emissions. As an alternative, an owner or 
operator may elect to sample dioxins/furans by installing, calibrating, 
maintaining, and operating a continuous automated sampling system for 
monitoring dioxin/furan emissions as specified in paragraph (c)(6) of 
this section. For Method 23 sampling, the minimum sample time shall be 
4 hours per test run. If the affected facility has selected the toxic 
equivalency standards for dioxins/furans, under Sec.  60.52c, the 
following procedures shall be used to determine compliance:
* * * * *
    (10) EPA Reference Method 26 or 26A of appendix A of this part 
shall be used to measure HCl emissions, with the additional 
requirements for Method 26A specified in paragraphs (b)(10)(i) through 
(iii) of this section. As an alternative, HCl CEMS may be used as 
specified in paragraph (c)(4) of this section. If the affected facility 
has selected the percentage reduction standards for HCl under Sec.  
60.52c, the percentage reduction in HCl emission (%RHCl) is 
computed using the following formula:

(%RHCl) = (Ei-Eo)/Ei x 100

Where:

%RHCl=percentage reduction of HCl emissions achieved;
Ei=HCl emission concentration measured at the control 
device inlet, corrected to 7 percent oxygen (dry basis); and
Eo=HCl emission concentration measured at the control 
device outlet, corrected to 7 percent oxygen (dry basis).

    (i) The probe and filter shall be conditioned prior to sampling 
using the procedure described in paragraphs (b)(10)(i)(A) through (C) 
of this section.
    (A) Assemble the sampling train(s) and conduct a conditioning run 
by collecting between 14 liters per minute (L/min)--(0.5 cubic feet per 
minute (ft \3\/min)) and 30 L/min (1.0 ft \3\/min) of gas over a 1-hour 
period. Follow the sampling procedures outlined in section 8.1.5 of 
Method 26A of appendix A of this part. For the conditioning run, water 
may be used as the impinger solution.
    (B) Remove the impingers from the sampling train and replace with a 
fresh impinger train for the sampling run, leaving the probe and filter 
(and cyclone, if used) in position. Do not recover the filter or rinse 
the probe before the first run. Thoroughly rinse the impingers used in 
the preconditioning run with deionized water and discard these rinses.
    (C) The probe and filter assembly shall be conditioned by the stack 
gas and shall not be recovered or cleaned until the end of testing.
    (ii) For the duration of sampling, a temperature around the probe 
and filter (and cyclone, if used) between 120 [deg]C (248 [deg]F) and 
134 [deg]C (273 [deg]F) shall be maintained.
    (iii) If water droplets are present in the sample gas stream, the 
requirements specified in paragraphs (b)(10)(iii)(A) and (B) of this 
section shall be met.
    (A) The cyclone described in section 6.1.4 of EPA Reference Method 
26A of appendix A of this part shall be used.
    (B) The post-test moisture removal procedure described in section 
8.1.6 of EPA Reference Method 26A of appendix A of this part shall be 
used.
    (11) EPA Reference Method 29 of appendix A of this part shall be 
used to measure Pb, Cd, and Hg emissions. As an alternative, Hg 
emissions may be measured using ASTM D6784-02. As an alternative for 
Pb, Cd, and Hg, multi-metals CEMS, or Hg CEMS, may be used as specified 
in paragraph (c)(4) of this section. If the affected facility has 
selected the percentage reduction standards for metals under Sec.  
60.52c, the percentage reduction in emissions (%Rmetal) is 
computed using the following formula:

(%Rmetal) = (Ei-Eo)/Ei x 
100

Where:

%Rmetal=percentage reduction of metal emission (Pb, Cd, 
or Hg) achieved;
Ei=metal emission concentration (Pb, Cd, or Hg) measured 
at the control device inlet, corrected to 7 percent oxygen (dry 
basis); and
Eo=metal emission concentration (Pb, Cd, or Hg) measured 
at the control device outlet, corrected to 7 percent oxygen (dry 
basis).
* * * * *
    (c) * * *
    (2) Except as provided in paragraphs (c)(4) and (c)(5) of this 
section, determine compliance with the PM, CO, and HCl emission limits 
by conducting an annual performance test (no more than 12 months 
following the previous performance test) using the applicable 
procedures and test methods listed in paragraph (b) of this section. If 
all three performance tests over a 3-year period indicate compliance 
with the emission limit for a pollutant (PM, CO, or HCl), the owner or 
operator may forego a performance test for that pollutant for the 
subsequent 2 years. At a minimum, a performance test for PM, CO, and 
HCl shall be conducted every third year (no more than 36 months 
following the previous performance test). If a performance test 
conducted every third year indicates compliance with the emission limit 
for a pollutant (PM, CO, or HCl), the owner or operator may forego a 
performance test for that pollutant for an additional 2 years. If any 
performance test indicates noncompliance with the respective emission 
limit, a performance test for that pollutant shall be conducted 
annually until all annual performance tests over a 3-year period 
indicate compliance with the emission limit. The use of the bypass 
stack during a performance test shall invalidate the performance test.
    (3) For large HMIWI under Sec.  60.50c(a)(1) and (a)(2) and for all 
HMIWI under Sec.  60.50c(a)(3) and (a)(4), determine compliance with 
the visible emission limits for fugitive emissions from flyash/bottom 
ash storage and handling by conducting a performance test using EPA 
Reference Method 22 on an annual basis (no more than 12 months 
following the previous performance test).
    (4) Facilities using optional CEMS to demonstrate compliance with 
the PM, CO, HCl, Pb, Cd, and/or Hg emission limits under Sec.  60.52c 
shall:
    (i) Determine compliance with the appropriate emission limit(s) 
using a 24-hour block average, calculated as specified in section 
12.4.1 of EPA Reference Method 19 of appendix A of this part.
    (ii) Operate all CEMS in accordance with the applicable procedures 
under appendices B and F of this part. For those CEMS for which 
performance specifications have not yet been promulgated (HCl, multi-
metals), this option takes effect on the date a final performance 
specification is published in the Federal Register or the date of 
approval of a site-specific monitoring plan.
    (iii) Be allowed to substitute use of an HCl CEMS for the HCl 
annual performance test, minimum HCl sorbent flow rate, and minimum 
scrubber liquor pH to demonstrate compliance with the HCl emission 
limit.
    (iv) Be allowed to substitute use of a PM CEMS for the PM annual 
performance test and minimum pressure drop across the wet scrubber, if 
applicable, to demonstrate compliance with the PM emission limit.
    (v) Be allowed to substitute use of a CO CEMS for the CO annual 
performance test and minimum secondary chamber temperature to 
demonstrate compliance with the CO emission limit.
    (5) For affected facilities under Sec.  60.50c(a)(3) and (a)(4), 
determine compliance with the CO emission limit using a CO CEMS 
according to paragraphs (c)(5)(i) and (c)(5)(ii) of this section:

[[Page 5547]]

    (i) Determine compliance with the CO emission limit using a 24-hour 
block average, calculated as specified in section 12.4.1 of EPA 
Reference Method 19 of appendix A of this part.
    (ii) Operate the CO CEMS in accordance with the applicable 
procedures under appendices B and F of this part.
    (iii) Use of a CO CEMS may be substituted for the CO annual 
performance test and minimum secondary chamber temperature to 
demonstrate compliance with the CO emission limit.
    (6) Facilities using a continuous automated sampling system to 
demonstrate compliance with the dioxin/furan emission limits under 
Sec.  60.52c shall record the output of the system and analyze the 
sample using EPA Reference Method 23 of appendix A of this part. This 
option to use a continuous automated sampling system takes effect on 
the date a final performance specification applicable to dioxin/furan 
from monitors is published in the Federal Register or the date of 
approval of a site-specific monitoring plan. The owner or operator of 
an affected facility who elects to continuously sample dioxin/furan 
emissions instead of sampling and testing using EPA Reference Method 23 
shall install, calibrate, maintain, and operate a continuous automated 
sampling system and shall comply with the requirements specified in 
Sec.  60.58b(p) and (q) of subpart Eb of this part.
    (d) Except as provided in paragraphs (c)(4), (c)(5), and (c)(6) of 
this section, the owner or operator of an affected facility equipped 
with a dry scrubber followed by a fabric filter, a wet scrubber, or a 
dry scrubber followed by a fabric filter and wet scrubber shall:
* * * * *
    (e) * * *
    (6) For HMIWI under Sec.  60.50c(a)(3) and (a)(4), operation of the 
affected facility above the CO emission limit as measured by the CO 
CEMS shall constitute a violation of the CO emission limit.
    (7) For HMIWI under Sec.  60.50c(a)(3) and (a)(4), failure to 
initiate corrective action within 1 hour of a bag leak detection system 
alarm; or failure to operate and maintain the fabric filter such that 
the alarm is not engaged for more than 5 percent of the total operating 
time in a 6-month block reporting period shall constitute a violation 
of the PM emission limit. If inspection of the fabric filter 
demonstrates that no corrective action is required, no alarm time is 
counted. If corrective action is required, each alarm is counted as a 
minimum of 1 hour. If it takes longer than 1 hour to initiate 
corrective action, the alarm time is counted as the actual amount of 
time taken to initiate corrective action. If the bag leak detection 
system is used to demonstrate compliance with the opacity limit, this 
would also constitute a violation of the opacity emission limit.
    (f) * * *
    (7) For HMIWI under Sec.  60.50c(a)(3) and (a)(4), operation of the 
affected facility above the CO emission limit as measured by the CO 
CEMS shall constitute a violation of the CO emission limit.
    (8) For all HMIWI, operation of the affected facility above the PM, 
CO, HCl, Pb, Cd, and/or Hg emission limit as measured by the CEMS 
specified in paragraph (c)(4) of this section shall constitute a 
violation of the applicable emission limit.
    (9) For all HMIWI, operation of the affected facility above the 
CDD/CDF emission limit as measured by the continuous automated sampling 
system specified in paragraph (c)(6) of this section shall constitute a 
violation of the CDD/CDF emission limit.
    (g) * * *
    (6) For HMIWI under Sec.  60.50c(a)(3) and (a)(4), operation of the 
affected facility above the CO emission limit as measured by the CO 
CEMS shall constitute a violation of the CO emission limit.
    (7) For HMIWI under Sec.  60.50c(a)(3) and (a)(4), failure to 
initiate corrective action within 1 hour of a bag leak detection system 
alarm; or failure to operate and maintain the fabric filter such that 
the alarm is not engaged for more than 5 percent of the total operating 
time in a 6-month block reporting period shall constitute a violation 
of the PM emission limit. If inspection of the fabric filter 
demonstrates that no corrective action is required, no alarm time is 
counted. If corrective action is required, each alarm is counted as a 
minimum of 1 hour. If it takes longer than 1 hour to initiate 
corrective action, the alarm time is counted as the actual amount of 
time taken to initiate corrective action. If the bag leak detection 
system is used to demonstrate compliance with the opacity limit, this 
would also constitute a violation of the opacity emission limit.
    (8) For all HMIWI, operation of the affected facility above the PM, 
CO, HCl, Pb, Cd, and/or Hg emission limit as measured by the CEMS 
specified in paragraph (c)(4) of this section shall constitute a 
violation of the applicable emission limit.
    (9) For all HMIWI, operation of the affected facility above the 
CDD/CDF emission limit as measured by the continuous automated sampling 
system specified in paragraph (c)(6) of this section shall constitute a 
violation of the CDD/CDF emission limit.
* * * * *
    (k) The owner or operator of an affected facility may use the 
results of previous emissions tests to demonstrate compliance with the 
emission limits, provided that the conditions in paragraphs (k)(1) 
through (k)(3) of this section are met:
    (1) The previous emissions tests shall have been conducted using 
the applicable procedures and test methods listed in paragraph (b) of 
this section. Previous emissions test results obtained using EPA-
accepted voluntary consensus standards are also acceptable.
    (2) The HMIWI at the affected facility shall be operated in a 
manner (e.g., with charge rate, secondary chamber temperature, etc.) 
that would be expected to result in the same or lower emissions than 
observed during the previous emissions test(s) and the HMIWI may not 
have been modified such that emissions would be expected to exceed 
(notwithstanding normal test-to-test variability) the results from 
previous emissions test(s).
    (3) The previous emissions test(s) shall have been conducted in 
1997 or later.
    14. Section 60.57c is amended as follows:
    a. By revising paragraph (a);
    b. By adding paragraph (e);
    c. By adding paragraph (f); and
    d. By adding paragraph (g).

Sec.  60.57c  Monitoring requirements

    (a) Except as provided in Sec.  60.56c(c)(4) through (c)(6), the 
owner or operator of an affected facility shall install, calibrate (to 
manufacturers' specifications), maintain, and operate devices (or 
establish methods) for monitoring the applicable maximum and minimum 
operating parameters listed in Table 3 to this subpart (unless optional 
CEMS are used as a substitute for certain parameters as specified) such 
that these devices (or methods) measure and record values for these 
operating parameters at the frequencies indicated in Table 3 at all 
times except during periods of startup and shutdown.
* * * * *
    (e) The owner or operator of an affected facility shall ensure that 
each HMIWI subject to the emission limits in Sec.  60.52c undergoes an 
initial air pollution control device inspection that is at least as 
protective as the following:

[[Page 5548]]

    (1) At a minimum, an inspection shall include the following:
    (i) Inspect air pollution control device(s) for proper operation, 
if applicable;
    (ii) Ensure proper calibration of thermocouples, sorbent feed 
systems, and any other monitoring equipment; and
    (iii) Generally observe that the equipment is maintained in good 
operating condition.
    (2) Within 10 operating days following an air pollution control 
device inspection, all necessary repairs shall be completed unless the 
owner or operator obtains written approval from the Administrator 
establishing a date whereby all necessary repairs of the designated 
facility shall be completed.
    (f) The owner or operator of an affected facility shall ensure that 
each HMIWI subject to the emission limits under Sec.  60.52c undergoes 
an air pollution control device inspection annually (no more than 12 
months following the previous annual air pollution control device 
inspection), as outlined in paragraphs (e)(1) and (e)(2) of this 
section.
    (g) For affected facilities under Sec.  60.50c(a)(3) and (a)(4) 
using an air pollution control device that includes a fabric filter and 
not using PM CEMS, determine compliance with the PM emission limit 
using a bag leak detection system and meet the requirements in 
paragraphs (g)(1) through (g)(12) of this section for each bag leak 
detection system. Affected facilities under Sec.  60.50c(a)(1) and 
(a)(2) may elect to demonstrate continuous compliance with the PM 
emission limit using a bag leak detection system and meet the 
requirements in paragraphs (g)(1) through (g)(12) of this section.
    (1) Each triboelectric bag leak detection system shall be 
installed, calibrated, operated, and maintained according to the 
``Fabric Filter Bag Leak Detection Guidance,'' (EPA 454/R-98-015, 
September 1997). This document is available from the U.S. Environmental 
Protection Agency (U.S. EPA); Office of Air Quality Planning and 
Standards; Sector Policies and Programs Division; Measurement Policy 
Group (D-243-02), Research Triangle Park, NC 27711. This document is 
also available on the Technology Transfer Network (TTN) under Emission 
Measurement Center Continuous Emission Monitoring. Other types of bag 
leak detection systems shall be installed, operated, calibrated, and 
maintained in a manner consistent with the manufacturer's written 
specifications and recommendations.
    (2) The bag leak detection system shall be certified by the 
manufacturer to be capable of detecting PM emissions at concentrations 
of 10 milligrams per actual cubic meter (0.0044 grains per actual cubic 
foot) or less.
    (3) The bag leak detection system sensor shall provide an output of 
relative PM loadings.
    (4) The bag leak detection system shall be equipped with a device 
to continuously record the output signal from the sensor.
    (5) The bag leak detection system shall be equipped with an audible 
alarm system that will sound automatically when an increase in relative 
PM emissions over a preset level is detected. The alarm shall be 
located where it is easily heard by plant operating personnel.
    (6) For positive pressure fabric filter systems, a bag leak 
detector shall be installed in each baghouse compartment or cell.
    (7) For negative pressure or induced air fabric filters, the bag 
leak detector shall be installed downstream of the fabric filter.
    (8) Where multiple detectors are required, the system's 
instrumentation and alarm may be shared among detectors.
    (9) The baseline output shall be established by adjusting the range 
and the averaging period of the device and establishing the alarm set 
points and the alarm delay time according to section 5.0 of the 
``Fabric Filter Bag Leak Detection Guidance.''
    (10) Following initial adjustment of the system, the sensitivity or 
range, averaging period, alarm set points, or alarm delay time may not 
be adjusted. In no case may the sensitivity be increased by more than 
100 percent or decreased more than 50 percent over a 365-day period 
unless such adjustment follows a complete fabric filter inspection that 
demonstrates that the fabric filter is in good operating condition. 
Each adjustment shall be recorded.
    (11) Record the results of each inspection, calibration, and 
validation check.
    (12) Initiate corrective action within 1 hour of a bag leak 
detection system alarm; operate and maintain the fabric filter such 
that the alarm is not engaged for more than 5 percent of the total 
operating time in a 6-month block reporting period. If inspection of 
the fabric filter demonstrates that no corrective action is required, 
no alarm time is counted. If corrective action is required, each alarm 
is counted as a minimum of 1 hour. If it takes longer than 1 hour to 
initiate corrective action, the alarm time is counted as the actual 
amount of time taken to initiate corrective action.
    15. Section 60.58c is amended as follows:
    a. By adding paragraphs (b)(2)(xvi) through (xviii);
    b. By revising paragraph (b)(6);
    c. By revising paragraph (c) introductory text;
    d. By revising paragraph (c)(2);
    e. By adding paragraph (c)(4);
    f. By revising paragraph (d) introductory text;
    g. By adding paragraphs (d)(9) through (11); and
    h. By adding paragraph (g).

Sec.  60.58c  Reporting and recordkeeping requirements.

* * * * *
    (b) * * *
    (2) * * *
    (xvi) Records of the annual air pollution control device 
inspections, any required maintenance, and any repairs not completed 
within 10 days of an inspection or the timeframe established by the 
Administrator.
    (xvii) For affected facilities using a bag leak detection system, 
records of each alarm, the time of the alarm, the time corrective 
action was initiated and completed, and a brief description of the 
cause of the alarm and the corrective action taken.
    (xviii) For affected facilities under Sec.  60.50c(a)(3) and 
(a)(4), concentrations of CO as determined by the continuous emission 
monitoring system.
* * * * *
    (6) The results of the initial, annual, and any subsequent 
performance tests conducted to determine compliance with the emission 
limits and/or to establish or re-establish operating parameters, as 
applicable, and a description of how the operating parameters were 
established or re-established, if applicable.
* * * * *
    (c) The owner or operator of an affected facility shall submit the 
information specified in paragraphs (c)(1) through (c)(4) of this 
section no later than 60 days following the initial performance test. 
All reports shall be signed by the facilities manager.
* * * * *
    (2) The values for the site-specific operating parameters 
established pursuant to Sec.  60.56c(d) or Sec.  60.56c(i), as 
applicable, and a description of how the operating parameters were 
established during the initial performance test.
* * * * *
    (4) For each affected facility that uses a bag leak detection 
system, analysis and supporting documentation

[[Page 5549]]

demonstrating conformance with EPA guidance and specifications for bag 
leak detection systems in Sec.  60.57c(g).
    (d) An annual report shall be submitted 1 year following the 
submission of the information in paragraph (c) of this section and 
subsequent reports shall be submitted no more than 12 months following 
the previous report (once the unit is subject to permitting 
requirements under title V of the Clean Air Act, the owner or operator 
of an affected facility must submit these reports semiannually). The 
annual report shall include the information specified in paragraphs 
(d)(1) through (9) of this section. All reports shall be signed by the 
facilities manager.
* * * * *
    (9) Records of the annual air pollution control device inspection, 
any required maintenance, and any repairs not completed within 10 days 
of an inspection or the timeframe established by the Administrator.
    (10) For affected facilities using a bag leak detection system, 
records of each alarm, the time of the alarm, the time corrective 
action was initiated and completed, and a brief description of the 
cause of the alarm and the corrective action taken.
    (11) For affected facilities under Sec.  60.50c(a)(3) and (a)(4), 
concentrations of CO as determined by the continuous emission 
monitoring system.
* * * * *
    (g) The owner or operator of an affected facility that uses the 
results of previous emissions tests to demonstrate compliance with the 
emission limits shall submit the information specified in paragraphs 
(g)(1) through (g)(4) of this section no later than [DATE 30 DAYS AFTER 
DATE OF PUBLICATION OF FINAL RULE]. All reports shall have been signed 
by the facility's manager.
    (1) The previous emissions test results as recorded using the 
methods and procedures in Sec.  60.56c(b)(1) through (12), as 
applicable. Previous emissions test results recorded using EPA-accepted 
voluntary consensus standards are also acceptable.
    (2) Certification that the test results are representative of 
current operations.
    (3) The values for the site-specific operating parameters 
established pursuant to Sec.  60.56c(d) or (i), as applicable.
    (4) The waste management plan as specified in Sec.  60.55c.
    16. Table 1 to subpart Ec is revised to read as follows:

              Table 1 to Subpart Ec of Part 60.--Emission Limits for Small, Medium, and Large HMIWI
----------------------------------------------------------------------------------------------------------------
                                                                       Emission limits  HMIWI size
           Pollutant                Units  (7 percent   --------------------------------------------------------
                                    oxygen dry basis)          Small              Medium             Large
----------------------------------------------------------------------------------------------------------------
1. Units for which construction is commenced after June 20, 1996 but no later than February 6, 2007 or for which
 modification is commenced on or after March 16, 1998 but no later than [THE DATE 6 MONTHS AFTER PROMULGATION OF
                                                 THE FINAL RULE]
----------------------------------------------------------------------------------------------------------------
Particulate matter.............  Milligrams per dry      41 (0.018).......  21 (0.0090)......  21 (0.0090).
                                  standard cubic meter
                                  (grains per dry
                                  standard cubic foot).
Carbon monoxide................  Parts per million by    32 \1\...........  32 \1\...........  32 \1\.
                                  volume.
Dioxins/furans.................  Nanograms per dry       111 (49) or 2.1    20 (8.7) or 0.53   20 (8.7) or 0.53
                                  standard cubic meter    (0.92).            (0.23).            (0.23).
                                  total dioxins/furans
                                  (grains per billion
                                  dry standard cubic
                                  feet) or nanograms
                                  per dry standard
                                  cubic meter TEQ
                                  (grains per billion
                                  dry standard cubic
                                  feet).
Hydrogen chloride..............  Parts per million by    15 or 99%........  15 or 99%........  15 or 99%.
                                  volume or percent
                                  reduction.
Sulfur dioxide.................  Parts per million by    46 \1\...........  46 \1\...........  46 \1\.
                                  volume.
Nitrogen oxides................  Parts per million by    225 \1\..........  225 \1\..........  225 \1\.
                                  volume.
Lead...........................  Milligrams per dry      0.78 \1\ (0.34)    0.060 (0.026) or   0.060 (0.026) or
                                  standard cubic meter    or 71%.            98%.               98%.
                                  (grains per thousand
                                  dry standard cubic
                                  feet) or percent
                                  reduction.
Cadmium........................  Milligrams per dry      0.11 \1\ (0.048)   0.030 (0.013) or   0.030 (0.013) or
                                  standard cubic meter    or 66%.            93%.               93%.
                                  (grains per thousand
                                  dry standard cubic
                                  feet) or percent
                                  reduction.
Mercury........................  Milligrams per dry      0.47 \1\ (0.21)    0.45 \1\ (0.20)    0.45 \1\ (0.20)
                                  standard cubic meter    or 87%.            or 87%.            or 87%.
                                  (grains per thousand
                                  dry standard cubic
                                  feet) or percent
                                  reduction.
----------------------------------------------------------------------------------------------------------------
2. Units for which construction is commenced after February 6, 2007 or for which modification is commenced after
                            [THE DATE 6 MONTHS AFTER PROMULGATION OF THE FINAL RULE]
----------------------------------------------------------------------------------------------------------------
Particulate matter.............  Milligrams per dry      41 (0.018).......  21 (0.0090)......  21 (0.0090).
                                  standard cubic meter
                                  (grains per dry
                                  standard cubic foot).
Carbon monoxide................  Parts per million by    25...............  25...............  25.
                                  volume.
Dioxins/furans.................  Nanograms per dry       111 (49) or 2.0    16 (7.0) or 0.21   16 (7.0) or 0.21
                                  standard cubic meter    (0.87).            (0.092).           (0.092).
                                  total dioxins/furans
                                  (grains per billion
                                  dry standard cubic
                                  feet) or nanograms
                                  per dry standard
                                  cubic meter TEQ
                                  (grains per billion
                                  dry standard cubic
                                  feet).
Hydrogen chloride..............  Parts per million by    15 or 99%........  15 or 99%........  15 or 99%.
                                  volume or percent
                                  reduction.
Sulfur dioxide.................  Parts per million by    28...............  21...............  21.
                                  volume.
Nitrogen oxides................  Parts per million by    212..............  212..............  212.
                                  volume.
Lead...........................  Milligrams per dry      0.64 (0.28) or     0.060 (0.026) or   0.060 (0.026) or
                                  standard cubic meter    71%.               99%.               99%.
                                  (grains per thousand
                                  dry standard cubic
                                  feet) or percent
                                  reduction.

[[Page 5550]]

Cadmium........................  Milligrams per dry      0.060 (0.026) or   0.0050 (0.0022)    0.0050 (0.0022)
                                  standard cubic meter    74%.               or 99%.            or 99%.
                                  (grains per thousand
                                  dry standard cubic
                                  feet) or percent
                                  reduction.
Mercury........................  Milligrams per dry      0.33 (0.14) or     0.19 (0.083) or    0.19 (0.083) or
                                  standard cubic meter    96%.               96%.               96%.
                                  (grains per thousand
                                  dry standard cubic
                                  feet) or percent
                                  reduction.
----------------------------------------------------------------------------------------------------------------
\1\ Emission limit is less stringent than the corresponding limit for existing sources contained in subpart Ce.
  Sources that would be subject to the emission limits in this table also would be subject to regulation under
  State plans or Federal plans that would implement subpart Ce and would be subject to limits at least as
  stringent as those in subpart Ce.

[FR Doc. E7-1617 Filed 2-5-07; 8:45 am]

BILLING CODE 6560-50-P