Federal Register: Part II [40 CFR Part 63]

ENVIRONMENTAL PROTECTION AGENCY

Treasury Department

CFR Citation: 40 CFR Part 63

RIN ID: RIN 2060-AG67

OAR ID: [OAR-2002-0060; FRL-7417-8]

NOTICE: Part II

DOCUMENT ACTION: Proposed rule.

SUBJECT CATEGORY: National Emission Standards for Hazardous Air Pollutants for Stationary Combustion Turbines

DATES: Comments. Submit comments on or before February 13, 2003.
Public Hearing. If anyone contacts us requesting to speak at a public hearing by January 24, 2003, we will hold a public hearing on January 29, 2003.

DOCUMENT SUMMARY: This action proposes national emission standards for hazardous air pollutants (NESHAP) for stationary combustion turbines. We have identified stationary combustion turbines as major sources of hazardous air pollutants (HAP) emissions such as formaldehyde, toluene, benzene, and acetaldehyde. The proposed NESHAP would implement section 112(d) of the Clean Air Act (CAA) by requiring all major sources to meet HAP emission standards reflecting the application of the maximum achievable control technology (MACT) for combustion turbines. We estimate that 20 percent of the stationary combustion turbines affected by the proposed rule will be located at major sources. As a result, the environmental, energy, and economic impacts presented in this preamble reflect these estimates. The proposed standards would protect public health by reducing exposure to air pollution, by reducing total national HAP emissions by an estimated 81 tons/year in the 5th year after the standards are promulgated. This action also proposes to add Method 323 of 40 CFR part 63, appendix A for the measurement of formaldehyde emissions from natural gasfired stationary sources.

SUMMARY: Environmental Protection Agency,

SUPPLEMENTAL INFORMATION

Regulated Entities. Categories and entities potentially regulated by this action include:
Category SIC NAICS Examples of regulated entities Any industry using a stationary combustion 4911 2211 Electric power generation, turbine as defined in the regulation. transmission, or distribution. 4922 486210 Natural gas transmission. 1311 211111 Crude petroleum and natural gas production. 1321 211112 Natural gas liquids producers. 4931 221 Electric and other services combined.

This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this action. To determine whether your facility is regulated by this action, you should examine the applicability criteria in Sec. 63.6085 of the proposed rule. If you have any questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding FOR FURTHER INFORMATION CONTACT section.

Docket. The EPA has established an official public docket for this action under Docket ID No. OAR20020060. The official public docket consists of the documents specifically referenced in this action, any public comments received, and other information related to this action. Although a part of the official docket, the public docket does not include Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. The official public docket is the collection of materials that is available for public viewing at the Air and Radiation Docket in the EPA Docket Center, (EPA/DC) EPA West, Room B108, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket Center 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 Reading Room is (202) 5661744, and the telephone number for the Air and Radiation Docket is (202) 5661742. A reasonable fee may be charged for copying docket materials.

Electronic Access. You may access this Federal Register document electronically through the EPA Internet under the Federal Register listings at http://www.epa.gov/fedrgstr/.

An electronic version of the public docket is available through EPA's electronic public docket and comment system, EPA Dockets. You may use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public comments, access the index listing of the contents of the official public docket, and to access those documents in the public docket that are available electronically. Once in the system, select ``search,'' then key in the appropriate docket identification number.

Certain types of information will not be placed in the EPA Dockets. Information claimed as CBI and other information whose disclosure is restricted by statute, which is not included in the official public docket, will not be available for public viewing in EPA's electronic public docket. The EPA's policy is that copyrighted material will not be placed in EPA's electronic public docket but will be available only in printed paper form in the official public docket. To the extent feasible, publicly available docket materials will be made available in EPA's electronic public docket. When a document is selected from the index list in EPA Dockets, the system will identify
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whether the document is available for viewing in EPA's electronic public docket. Although not all docket materials may be available electronically, you may still access any of the publicly available docket materials through the docket facility identified above. The EPA intends to work towards providing electronic access to all of the publicly available docket materials through EPA's electronic public docket.

For public commenters, it is important to note that EPA's policy is that public comments, whether submitted electronically or on paper, will be made available for public viewing in EPA's electronic public docket as EPA receives them and without change, unless the comment contains copyrighted material, CBI, or other information whose disclosure is restricted by statute. When EPA identifies a comment containing copyrighted material, EPA will provide a reference to that material in the version of the comment that is placed in EPA's electronic public docket. The entire printed comment, including the copyrighted material, will be available in the public docket.

Public comments submitted on computer disks that are mailed or delivered to the docket will be transferred to EPA's electronic public docket. Public comments that are mailed or delivered to the Docket will be scanned and placed in EPA's electronic public docket. Where practical, physical objects will be photographed, and the photograph will be placed in EPA's electronic public docket along with a brief description written by the docket staff.

For additional information about EPA's electronic public docket visit EPA Dockets online or see 67 FR 38102, May 31, 2002.

You may submit comments electronically, by mail, or through hand delivery/courier. To ensure proper receipt by EPA, identify the appropriate docket identification number in the subject line on the first page of your comment. Please ensure that your comments are submitted within the specified comment period. Comments received after the close of the comment period will be marked ``late.'' The EPA is not required to consider these late comments. However, late comments may be considered if time permits. Electronically. If you submit an electronic comment as prescribed below, EPA recommends that you include your name, mailing address, and an email address or other contact information in the body of your comment. Also include this contact information on the outside of any disk or CD ROM you submit, and in any cover letter accompanying the disk or CD ROM. This ensures that you can be identified as the submitter of the comment and allows EPA to contact you in case EPA cannot read your comment due to technical difficulties or needs further information on the substance of your comment. The EPA's policy is that EPA will not edit your comment, and any identifying or contact information provided in the body of a comment will be included as part of the comment that is placed in the official public docket and made available in EPA's electronic public docket. 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.

Your use of EPA's electronic public docket to submit comments to EPA electronically is EPA's preferred method for receiving comments. Go directly to EPA Dockets at http://www.epa.gov/edocket, and follow the online instructions for submitting comments. To access EPA's electronic public docket from the EPA Internet Home Page, select ``Information Sources,'' ``Dockets,'' and ``EPA Dockets.'' Once in the system, select ``search,'' and then key in Docket ID No. OAR20020060. The system is an ``anonymous access'' system, which means EPA will not know your identity, email address, or other contact information unless you provide it in the body of your comment.

Comments may be sent by electronic mail (email) to aandr docket@epa.gov, Attention Docket ID No. OAR20020060. In contrast to EPA's electronic public docket, EPA's email system is not an ``anonymous access'' system. If you send an email comment directly to the Docket without going through EPA's electronic public docket, EPA's email system automatically captures your email address. Email addresses that are automatically captured by EPA's email system are included as part of the comment that is placed in the official public docket and made available in EPA's electronic public docket.

You may submit comments on a disk or CD ROM that you mail to the mailing address identified below. These electronic submissions will be accepted in WordPerfect or ASCII file format. Avoid the use of special characters and any form of encryption.

By Mail. Send your comments (in duplicate if possible) to: Air and Radiation Docket and Information Center, U.S. EPA, Mailcode: 6102T, 1200 Pennsylvania Ave., NW, Washington, DC, 20460, Attention Docket ID No. OAR20020060. The EPA requests a separate copy also be sent to the contact person listed above (see FOR FURTHER INFORMATION CONTACT).

By Hand Delivery or Courier. Deliver your comments to: EPA Docket Center, Room B108, 1301 Constitution Ave., NW, Washington, DC, 20460, Attention Docket ID No. OAR20020060. Such deliveries are only accepted during the Docket's normal hours of operation as identified above.

Do not submit information that you consider to be CBI electronically through EPA's electronic public docket or by email. Send or deliver information identified as CBI only to the following address: Mr. Sims Roy, c/o OAQPS Document Control Officer (Room C404 2), U.S. EPA, Research Triangle Park, 27711, Attention Docket ID No. OAR20020060. You may claim information that you submit to EPA as CBI by marking any part or all of that information as CBI (if you submit CBI on disk or CD ROM, 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 CBI). Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.

In addition to one complete version of the comment that includes any 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 and EPA's electronic public docket. If you submit the copy that does not contain CBI on disk or CD ROM, mark the outside of the disk or CDROM clearly that it does not contain CBI. Information not marked as CBI will be included in the public docket and EPA's electronic public docket without prior notice. 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.

You may find the following suggestions helpful for preparing your comments:

1. Explain your views as clearly as possible.

2. Describe any assumptions that you used.

3. Provide any technical information and/or data you used that support your views.

4. If you estimate potential burden or costs, explain how you arrived at your estimate.

5. Provide specific examples to illustrate your concerns.

6. Offer alternatives.

7. Make sure to submit your comments by the comment period deadline identified.

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8. To ensure proper receipt by EPA, identify the appropriate docket identification number in the subject line on the first page of your response. It would also be helpful if you provided the name, date, and Federal Register citation related to your comments.

Public Hearing. Persons interested in presenting oral testimony or inquiring as to whether a hearing is to be held should contact Mrs. Kelly Hayes, Combustion Group, Emission Standards Division (MDC439 01), U.S. EPA, Research Triangle Park, North Carolina 27711, (919) 541 5578 at least 2 days in advance of the public hearing. Persons interested in attending the public hearing must also call Mrs. Hayes to verify the time, date, and location of the hearing. The public hearing will provide interested parties the opportunity to present data, views, or arguments concerning the proposed rule. If a public hearing is requested and held, EPA will ask clarifying questions during the oral presentation but will not respond to the presentations or comments. Written statements and supporting information will be considered with equivalent weight as any oral statement and supporting information presented at a public hearing, if held.

Outline. The information presented in this preamble is organized as follows:

I. Background

A. What is the regulatory development background of the source category?

B. What is the source of authority for development of NESHAP?

C. What criteria are used in the development of NESHAP?

D. What are the health effects associated with HAP from stationary combustion turbines?
II. Summary of the Proposed Rule

A. Am I subject to the proposed rule?

B. What source categories and subcategories are affected by the proposed rule?

C. What are the primary sources of HAP emissions and what are the emissions?

D. What are the emission limitations and operating limitations?

E. What are the initial compliance requirements?

F. What are the continuous compliance provisions?

G. What monitoring and testing methods are available to measure these low concentrations of CO and formaldehyde?

H. What are the notification, recordkeeping and reporting requirements?

III. Rationale for Selecting the Proposed Standards

A. How did we select the source category and any subcategories?

B. What about stationary combustion turbines located at area sources?

C. What is the affected source?

D. How did we determine the basis and level of the proposed emission limitations for existing sources?

E. How did we determine the basis and level of the proposed emission limitations and operating limitations for new sources?

F. How did we select the format of the standard for new diffusion flame combustion turbines?

G. How did we select the initial compliance requirements?

H. How did we select the continuous compliance requirements?

I. How did we select the monitoring and testing methods to measure these low concentrations of CO and formaldehyde?

J. How did we select the notification, recordkeeping and reporting requirements?
IV. Summary of Environmental, Energy and Economic Impacts

A. What are the air quality impacts?

B. What are the cost impacts?

C. What are the economic impacts?

D. What are the nonair health, environmental and energy impacts? V. Solicitation of Comments and Public Participation

A. General

B. Can we achieve the goals of the proposed rule in a less costly manner?

C. Limited Use Subcategory

VI. Administrative Requirements

A. Executive Order 12866, Regulatory Planning and Review

B. Executive Order 13132, Federalism

C. Executive Order 13175, Consultation and Coordination with Indian Tribal Governments

D. Executive Order 13045, Protection of Children from Environmental Health Risks and Safety Risks

E. Executive Order 13211, Actions Concerning Regulations that Significantly Affect Energy Supply, Distribution, or Use

F. Unfunded Mandates Reform Act of 1995

G. Regulatory Flexibility Act (RFA), as Amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 U.S.C. 601 et seq.

H. Paperwork Reduction Act

I. National Technology Transfer and Advancement Act I. Background
A. What Is the Regulatory Development Background of the Source Category?

In September 1996, we chartered the Industrial Combustion Coordinated Rulemaking (ICCR) advisory committee under the Federal Advisory Committee Act (FACA). The committee's objective was to develop recommendations for regulations for several combustion source categories under sections 112 and 129 of the CAA. The ICCR advisory committee, also known as the Coordinating Committee, formed Source Work Groups for the various combustor types covered under the ICCR. One work group, the Combustion Turbine Work Group, was formed to research issues related to stationary combustion turbines. The Combustion Turbine Work Group submitted recommendations, information, and data analyses to the Coordinating Committee, which in turn considered them and submitted recommendations and information to us. The Committee's 2year charter expired in September 1998. We considered the Committee's
recommendations in developing the proposed rule for stationary combustion turbines.
B. What Is the Source of Authority for Development of NESHAP?

Section 112 of the CAA requires us to list categories and subcategories of major sources and area sources of HAP and to establish NESHAP for the listed source categories and subcategories. The stationary turbine source category was listed on July 16, 1992 (57 FR 31576). Major sources of HAP are those that have the potential to emit greater than 10 ton/yr of any one HAP or 25 ton/yr of any combination of HAP.

C. What Criteria Are Used in the Development of NESHAP?

Section 112 of the CAA requires that we establish NESHAP for the control of HAP from both new and existing major sources. The CAA requires the NESHAP to reflect the maximum degree of reduction in emissions of HAP that is achievable. This level of control is commonly referred to as the MACT.

The MACT floor is the minimum control level allowed for NESHAP and is defined under section 112(d)(3) of the CAA. In essence, the MACT floor ensures that the standard is set at a level that assures that all major sources achieve the level of control at least as stringent as that already achieved by the better controlled and lower emitting sources in each source category or subcategory. For new sources, the MACT standards cannot be less stringent than the emission control that is achieved in practice by the best controlled similar source. The MACT standards for existing sources can be less stringent than standards for new sources, but they cannot be less stringent than the average emission limitation achieved by the best performing 12 percent of existing sources in the category or subcategory (or the best performing 5 sources for categories or subcategories with fewer than 30 sources).

In developing MACT, we also consider control options that are more stringent than the floor. We may establish standards more stringent than the floor based on the consideration of cost of achieving the emissions
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reductions, any nonair quality health and environmental impacts, and energy requirements.
D. What Are the Health Effects Associated With HAP From Stationary Combustion Turbines?

Emission data collected during development of the proposed NESHAP show that several HAP are emitted from stationary combustion turbines. These HAP emissions are formed during combustion or result from HAP compounds contained in the fuel burned.

Among the HAP which have been measured in emission tests that were conducted at natural gas fired and distillate oil fired combustion turbines are: 1,3 butadiene, acetaldehyde, acrolein, benzene, ethylbenzene, formaldehyde, naphthalene, poly aromatic hydrocarbons (PAH) propylene oxide, toluene, and xylenes. Metallic HAP from distillate oil fired stationary combustion turbines that have been measured are: arsenic, beryllium, cadmium, chromium, lead, manganese, mercury, nickel, and selenium.

Although numerous HAP may be emitted from combustion turbines, only a few account for essentially all the mass of HAP emissions from stationary combustion turbines. These HAP are: formaldehyde, toluene, benzene, and acetaldehyde.

The HAP emitted in the largest quantity is formaldehyde. Formaldehyde is a probable human carcinogen and can cause irritation of the eyes and respiratory tract, coughing, dry throat, tightening of the chest, headache, and heart palpitations. Acute inhalation has caused bronchitis, pulmonary edema, pneumonitis, pneumonia, and death due to respiratory failure. Longterm exposure can cause dermatitis and sensitization of the skin and respiratory tract.

Other HAP emitted in significant quantities from stationary combustion turbines include toluene, benzene, and acetaldehyde. The health effect of primary concern for toluene is dysfunction of the central nervous system (CNS). Toluene vapor also causes narcosis. Controlled exposure of human subjects produced mild fatigue, weakness, confusion, lacrimation, and paresthesia; at higher exposure levels there were also euphoria, headache, dizziness, dilated pupils, and nausea. After effects included nervousness, muscular fatigue, and insomnia persisting for several days. Acute exposure may cause irritation of the eyes, respiratory tract, and skin. It may also cause fatigue, weakness, confusion, headache, and drowsiness. Very high concentrations may cause unconsciousness and death.

Benzene is a known human carcinogen. The health effects of benzene include nerve inflammation, CNS depression, and cardiac sensitization. Chronic exposure to benzene can cause fatigue, nervousness, irritability, blurred vision, and labored breathing and has produced anorexia and irreversible injury to the bloodforming organs; effects include aplastic anemia and leukemia. Acute exposure can cause dizziness, euphoria, giddiness, headache, nausea, staggering gait, weakness, drowsiness, respiratory irritation, pulmonary edema, pneumonia, gastrointestinal irritation, convulsions, and paralysis. Benzene can also cause irritation to the skin, eyes, and mucous membranes.

Acetaldehyde is a probable human carcinogen. The health effects for acetaldehyde are irritation of the eyes, mucous membranes, skin, and upper respiratory tract, and it is a CNS depressant in humans. Chronic exposure can cause conjunctivitis, coughing, difficult breathing, and dermatitis. Chronic exposure may cause heart and kidney damage, embryotoxicity, and teratogenic effects. Acetaldehyde is a potential carcinogen in humans.
II. Summary of the Proposed Rule

A. Am I Subject to the Proposed Rule?

The proposed rule applies to you if you own or operate a stationary combustion turbine which is located at a major source of HAP emissions. A major source of HAP emissions is a plant site that emits or has the potential to emit any single HAP at a rate of 10 tons (9.07 megagrams) or more per year or any combination of HAP at a rate of 25 tons (22.68 megagrams) or more per year.

Section 112(n)(4) of the CAA requires that the aggregation of HAP for purposes of determining whether an oil and gas production facility is major or nonmajor be done only with respect to particular sites within the source and not on a total aggregated site basis. We incorporated the requirements of section 112(n)(4) of the CAA into our NESHAP for Oil and Natural Gas Production Facilities in subpart HH of part 63. As in subpart HH, we plan to aggregate HAP emissions for the purposes of determining a major HAP source for turbines only with respect to particular sites within an oil and gas production facility. The sites are called surface sites and may include a combination of any of the following equipment; glycol dehydrators, tanks which have potential for flash emissions, reciprocating internal combustion engines and combustion turbines.

Six subcategories have been defined within the stationary combustion turbine source category. While all stationary combustion turbines are subject to the proposed rule, each subcategory has distinct requirements. For example, existing diffusion flame combustion turbines and stationary combustion turbines with a rated peak power output of less than 1.0 megawatt (MW) (at International Organization for Standardization (ISO) standard day conditions) are not required to comply with emission limitations, recordkeeping or reporting requirements in the proposed rule. New or reconstructed stationary combustion turbines and existing lean premix stationary combustion turbines with a rated peak power output of 1.0 MW or more that either operate exclusively as an emergency stationary combustion turbine, as a limited use stationary combustion turbine, or as a stationary combustion turbine which burns landfill gas or digester gas as its primary fuel must only comply with the initial notification requirements. New or reconstructed diffusion flame or lean premix combustion turbines must comply with emission limitations, recordkeeping and reporting requirements in the proposed rule. The emission limitations for each subcategory are summarized in Table 2 of this preamble. You must determine your source's subcategory to determine which requirements apply to your source.

The proposed rule does not apply to stationary combustion turbines located at an area source of HAP emissions. An area source of HAP emissions is a plant site that does not emit any single HAP at a rate of 10 tons (9.07 megagrams) or greater per year or any combination of HAP at a rate of 25 tons (22.68 megagrams) or greater per year. To determine whether a facility is a major source, EPA will accept HAP emissions estimated using HAP emission factors listed in Table 1 of this preamble.
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Table 1.Summary of HAP Emission Factors HAP emission Turbine Load Fuel factor (lb/ MMBtu) Diffusion Flame......................... All loads................. Natural Gas............... 0.0188 Diffusion Flame......................... 80%............ Natural Gas............... 0.00479 Diffusion Flame......................... All loads................. Diesel.................... 0.00241 Diffusion Flame......................... 80%............ Diesel.................... 0.00233 Lean Premix............................. All loads................. Natural Gas............... 0.000644 Lean Premix............................. 80%............ Natural Gas............... 0.000212

If the turbine mainly operates at high load, the emission factor for greater than 80 percent load should be used. If the turbine operates on varying loads, the emission factor for all loads should be used. Emission factors were developed based on data from the combustion turbines emissions database. A copy of the emissions database may be downloaded off the internet at http://www.epa.gov/ttn/atw/combust/turbine/turbpg.html .

The proposed rule does not cover duct burners. They are part of the waste heat recovery unit in a combined cycle system. Waste heat recovery units, whether part of a cogeneration system or a combined cycle system, are steam generating units and are not covered by the proposed rule.

Finally, the proposed rule does not apply to stationary combustion engine test cells/stands since these facilities will be covered by another NESHAP, 40 CFR part 63, subpart PPPPP.
B. What Source Categories and Subcategories Are Affected by the Proposed Rule?

The proposed rule covers stationary combustion turbines. A stationary combustion turbine is any simple cycle stationary combustion turbine, any regenerative/recuperative cycle stationary combustion turbine, the combustion turbine portion of any stationary cogeneration cycle combustion system, or the combustion turbine portion of any stationary combined cycle steam/electric generating system. Stationary means that the combustion turbine is not self propelled or intended to be propelled while performing its function. The combustion turbine may, however, be mounted on a vehicle for portability or transportability.

Stationary combustion turbines have been divided into the following six subcategories: (1) Emergency stationary combustion turbines, (2) limited use stationary combustion turbines, (3) stationary combustion turbines which fire landfill gas or digester gas as their primary fuel, (4) stationary combustion turbines of less than 1 MW rated peak power output, (5) stationary diffusion flame combustion turbines, and (6) stationary lean premix combustion turbines.

An emergency stationary combustion turbine means any stationary combustion turbine that operates as a mechanical or electrical power source when the primary power source for a facility has been rendered inoperable by an emergency situation. One example is emergency power for critical networks or equipment when electric power from the normal source of power is interrupted. Another example is to pump water in the case of fire or flood. Peaking units at electric utilities and other types of stationary combustion turbines that typically operate at low capacity factors, but are not confined to operation in an emergency, are not emergency stationary combustion turbines.

A limited use stationary combustion turbine means any stationary combustion turbine that operates 50 hours or less per calendar year. One example is a stationary combustion turbine used to stabilize electrical power voltage and protect sensitive electronic equipment during periods of brown outs. Another example is periodic operation of an emergency stationary combustion turbine to check readiness or perform maintenance checks. Since electrical power has not been interrupted during these readiness and maintenance checks, the stationary combustion turbine is not operating as an emergency stationary combustion turbine.

We are specifically soliciting comments on creating a subcategory of limited use combustion turbines with a capacity utilization of 10 percent or less. This is further discussed in the ``Solicitation of Comments and Public Participation'' section of this preamble.

Stationary combustion turbines which fire landfill gas or digester gas as their primary fuel qualify as a separate subcategory because the types of control available for these turbines are limited.

Stationary combustion turbines of less than 1 MW rated peak power output were also identified as a subcategory. These small stationary combustion turbines are few in number and, to our knowledge, none use emission control technology to reduce HAP. Given the very small size of these stationary combustion turbines and the lack of application of HAP emission control technologies, we have concerns about the applicability of HAP emission control technology to them.

The stationary diffusion flame combustion turbines subcategory includes only diffusion flame combustion turbines that are greater than 1 MW rated peak power output and are not emergency stationary combustion turbines, limited use stationary combustion turbines, or stationary combustion turbines which fire landfill gas or digester gas as their primary fuel. In a diffusion flame combustor, the fuel and air are injected at the combustor and are mixed only by diffusion prior to ignition. Hazardous air pollutants emissions from these turbines can be significantly decreased with the addition of air pollution control equipment.

The stationary lean premix combustion turbines subcategory includes only lean premix combustion turbines that are greater than 1 MW rated peak power output and are not emergency stationary combustion turbines, limited use stationary combustion turbines, or stationary combustion turbines which fire landfill gas or digester gas as their primary fuel. Lean premix technology, introduced in the 1990's, was developed to reduce NOX emissions without the use of add on controls. In a staged lean premix combustor, the air and fuel are thoroughly mixed to form a lean mixture before delivery to the combustor. The staged entry limits the flame temperature and the residence time at the peak flame temperature. Lean premix combustors emit lower levels of NOX, carbon monoxide (CO), formaldehyde and other HAP than diffusion flame combustion turbines.
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C. What Are the Primary Sources of HAP Emissions and What Are the Emissions?

The sources of emissions are the exhaust gases from combustion of gaseous and liquid fuels in a stationary combustion turbine. Hazardous air pollutants that are present in the exhaust gases from stationary combustion turbines include formaldehyde, toluene, benzene, and acetaldehyde.
D. What Are the Emission Limitations and Operating Limitations?

As the owner or operator of an existing lean premix stationary combustion turbine or a new or reconstructed stationary combustion turbine located at a major source of HAP emissions, you must comply with one of the following two emission limitations by the effective date of the standard (or upon startup if you start up your stationary combustion turbine after the effective date of the standard): (1) Reduce CO emissions in the exhaust from the new or reconstructed stationary combustion turbine by 95 percent or more, if you use an oxidation catalyst emission control device; or (2) reduce the concentration of formaldehyde in the exhaust from the new or reconstructed stationary combustion turbine to 43 parts per billion by volume or less, dry basis (ppbvd), at 15 percent oxygen, if you use means other than an oxidation catalyst emission control device.

There are no operating limitations if you choose to comply with the emission limitation for CO emission reduction. If you comply with the emission limitation for formaldehyde emissions and your stationary combustion turbine is not lean premix or diffusion flame, you must comply with any additional operating limitations approved by the Administrator, as discussed later.

Finally, as mentioned earlier, stationary combustion turbines with a rated peak power output of less than 1.0 MW, emergency stationary combustion turbines, limited use stationary combustion turbines, and stationary combustion turbines which burn landfill gas or digester gas as their primary fuel, are not required to comply with these emission limitations. In addition, existing diffusion flame stationary combustion turbines, are not required to comply with these emission limitations. The emission limitations for each subcategory are summarized in Table 2 of this preamble.
Table 2.Summary of Emission Limitations Subcategory Emission limitation Comment Existing Diffusion Flame Stationary None...................... No requirements. Combustion Turbine = 1.0 MW.
Existing Lean Premix Stationary (1) Reduce CO emissions by Combustion Turbine = 1.0 95% or more, if you use MW. an oxidation catalyst emission control device. or....................... (2) Reduce the
concentration of
formaldehyde to 43 ppbvd @ 15% O2, if you use means other than an oxidation catalyst emission control device. or
New/Reconstructed Stationary Combustion
Turbine = 1.0 MW.
Emergency Stationary Combustion Turbine No emission limitations... Initial notification requirements only. or....................................
Limited Use Stationary Combustion
Turbine
or....................................
Landfill/Digester Gas Stationary
Combustion Turbine.
<= 1 MW Stationary Combustion Turbine.. None...................... No requirements. E. What Are the Initial Compliance Requirements?

The initial compliance requirements for a stationary combustion turbine vary depending on the subcategory of your combustion turbine and your control strategy.

If you operate a new or reconstructed stationary combustion turbine and comply with the emission limitation for CO emission reduction, you must install a continuous emission monitoring system (CEMS) to measure CO and either carbon dioxide or oxygen simultaneously at the inlet and outlet of the oxidation catalyst emission control device. To demonstrate initial compliance, you must conduct an initial performance evaluation using Performance Specifications 3 and 4A of 40 CFR part 60, appendix B. You must demonstrate that the reduction of CO emissions is at least 95 percent using the first 4hour average after a successful performance evaluation. Your inlet and outlet measurements must be on a dry basis and corrected to 15 percent oxygen or equivalent carbon dioxide content. You must also conduct an annual relative accuracy test audit (RATA) of the CEMS using Performance Specifications 3 and 4A of 40 CFR part 60, appendix B.

If you operate a new or reconstructed combustion turbine or an existing lean premix combustion turbine and comply with the emission limitation for formaldehyde emissions, you must conduct an initial performance test using Test Method 320 of 40 CFR part 63, appendix A; ARB Method 430 of California Environmental Protection Agency, Air Resources Board, 2020 L Street, Sacramento, CA 95812; or EPA Solid Waste (SW)846 Method 0011 to demonstrate that the outlet concentration of formaldehyde is 43 ppbvd or less (corrected to 15 percent oxygen). Natural gasfired sources may also use the proposed Test Method 323 of 40 CFR part 63, appendix A, to measure formaldehyde. To correct to 15 percent oxygen, dry basis, you must measure oxygen using Method 3A or 3B of 40 CFR part 60, appendix A, and moisture using Method 4 of 40 CFR part 60, appendix A.

As stated previously, if you choose to comply with the emission limitation for formaldehyde emissions and your stationary combustion turbine is not lean premix or diffusion flame, you must also petition the Administrator for approval of operating limitations or approval of no operating limitations.

If you petition the Administrator for approval of operating limitations, your petition must include the following: (1) Identification of the specific parameters
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you propose to use as operating limitations; (2) a discussion of the relationship between these parameters and HAP emissions, identifying how HAP emissions change with changes in these parameters and how limitations on these parameters will serve to limit HAP emissions; (3) a discussion of how you will establish the upper and/or lower values for these parameters which will establish the limits on these parameters in the operating limitations; (4) a discussion identifying the methods you will use to measure and the instruments you will use to monitor these parameters, as well as the relative accuracy and precision of these methods and instruments; and (5) a discussion identifying the frequency and methods for recalibrating the instruments you will use for monitoring these parameters.

If you petition the Administrator for approval of no operating limitations, your petition must include the following: (1) Identification of the parameters associated with operation of the stationary combustion turbine and any emission control device which could change intentionally (e.g., operator adjustment, automatic controller adjustment, etc.) or unintentionally (e.g., wear and tear, error, etc.) on a routine basis or over time; (2) a discussion of the relationship, if any, between changes in these parameters and changes in HAP emissions; (3) for those parameters with a relationship to HAP emissions, a discussion of whether establishing limitations on these parameters would serve to limit HAP emissions; (4) for those parameters with a relationship to HAP emissions, a discussion of how you could establish upper and/or lower values for these parameters which would establish limits on these parameters in operating limitations; (5) for those parameters with a relationship to HAP emissions, a discussion identifying the methods you could use to measure these parameters and the instruments you could use to monitor them, as well as the relative accuracy and precision of these methods and instruments; (6) for these parameters, a discussion identifying the frequency and methods for recalibrating the instruments you could use to monitor them; and (7) a discussion of why, from your point of view, it is infeasible or unreasonable to adopt these parameters as operating limitations. F. What Are the Continuous Compliance Provisions?

Several general continuous compliance requirements apply to stationary combustion turbines required to comply with the emission limitations. You are required to comply with the emission limitations and the operating limitations (if applicable) at all times, except during startup, shutdown, and malfunction of your stationary combustion turbine. You must also operate and maintain your stationary combustion turbine, air pollution control equipment, and monitoring equipment according to good air pollution control practices at all times, including startup, shutdown, and malfunction. You must conduct all monitoring at all times that the stationary combustion turbine is operating, except during periods of malfunction of the monitoring equipment or necessary repairs and quality assurance or control activities, such as calibration checks.

To demonstrate continuous compliance with the CO emission reduction limitation, you must calibrate and operate your CEMS according to the requirements in 40 CFR 63.8. You must continuously monitor and record the CO concentration before and after the oxidation catalyst emission control device and calculate the percent reduction of CO emissions hourly. The reduction in CO emissions must be 95 percent or more, based on a rolling 4hour average, averaged every hour.

To demonstrate continuous compliance with the operating limitations (if applicable), you must continuously monitor the values of any parameters which have been approved by the Administrator as operating limitations.

The proposed rule does not require your lean premix combustion turbine to demonstrate continuous compliance. It is assumed that if you meet the low NOX emission levels required by your federally enforceable permit (or guaranteed by the turbine manufacturer if there is no permit level), your turbine is in compliance with the 43 ppbvd formaldehyde emission limit.
G. What Monitoring and Testing Methods Are Available to Measure These Low Concentrations of CO and Formaldehyde?

Continuous emissions monitoring systems are available which can accurately measure CO emission reduction at the low concentrations found in the combustion turbine exhaust following an oxidation catalyst emission control device. Our performance specification for CO CEMS (PS 4A) of 40 CFR part 60, appendix A, however, has not been updated recently and does not reflect the performance capabilities of these systems. We are currently undertaking a review of PS4A of 40 CFR part 60, appendix A, for CO CEMS and, in conjunction with this effort, we solicit comments on the performance capabilities of CO CEMS and their ability to accurately measure the low concentrations of CO experienced in the exhaust of a combustion turbine following an oxidation catalyst emission control device.

Similarly, our Fourier Transform Infrared (FTIR) test method, Method 320 of 40 CFR part 63, appendix A, as well as EPA SW846 Method 0011 and CARB Method 430, can be used to accurately measure formaldehyde concentrations in the exhaust of a combustion turbine as low as 43 ppbvd. As these test methods are currently written, however, they do not provide for this level of accuracy. These methods must be used with some revisions to achieve such accuracy.

As a result, we are currently undertaking a review of our FTIR method, Method 320 of 40 CFR part 63, appendix A, to incorporate revisions to ensure it can be used to accurately measure formaldehyde concentrations as low as 43 ppbvd in the exhaust from a combustion turbine. In conjunction with this effort, we solicit comments on revisions to Method 320 of 40 CFR part 63, appendix A, to ensure accurate measurement of such low concentrations of formaldehyde.

We are also proposing to add Method 323 of 40 CFR part 63, appendix A. Method 323 is for the measurement of formaldehyde emissions from natural gasfired stationary sources using acetyl acetone
derivitization. We solicit comments on the use of this method to measure low concentrations of formaldehyde.
H. What Are the Notification, Recordkeeping and Reporting Requirements?

You must submit all of the applicable notifications as listed in the NESHAP General Provisions (40 CFR part 63, subpart A), including an initial notification, notification of performance test or evaluation, and a notification of compliance, for each stationary combustion turbine which must comply with the emission limitations. If your new or reconstructed source is located at a major source, has greater than 1 MW rated peak power output, and is an emergency stationary combustion turbine, limited use stationary combustion turbine or a combustion turbine which fires landfill or digester gas as its primary fuel, you must submit only an initial notification.

For each combustion turbine subject to the emission limitations, you must
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record all of the data necessary to determine if you are in compliance with the emission limitations. Your records must be in a form suitable and readily available for review. You must also keep each record for 5 years following the date of each occurrence, measurement, maintenance, report, or record. Records must remain on site for at least 2 years and then can be maintained off site for the remaining 3 years.

You must submit a compliance report semiannually for each new or reconstructed stationary combustion turbine that must comply with the CO emission reduction limitation. This report must contain the company name and address, a statement by a responsible official that the report is accurate, a statement of compliance, or documentation of any deviation from the requirements of the proposed rule during the reporting period.
III. Rationale for Selecting the Proposed Standards
A. How Did We Select the Source Category and Any Subcategories?

Stationary combustion turbines can be major sources of HAP emissions and, as a result, we listed them as a major source category for regulatory development under section 112 of the CAA. Section 112 of the CAA allows us to establish subcategories within a source category for the purpose of regulation. Consequently, we evaluated several criteria associated with stationary combustion turbines which might serve as potential subcategories.

We identified six subcategories of stationary combustion turbines located at major sources: (1) Emergency stationary combustion turbines, (2) limited use stationary combustion turbines, (3) stationary combustion turbines which fire landfill gas or digester gas as their primary fuel, (4) stationary combustion turbines of less than 1 MW rated peak power output, (5) stationary diffusion flame combustion turbines, and (6) stationary lean premix combustion turbines.

Stationary combustion turbines can be classified as either diffusion flame or lean premix. We examined formaldehyde test data for both diffusion flame and lean premix stationary combustion turbines and observed that uncontrolled formaldehyde emissions for stationary lean premix combustion turbines are significantly lower than those of stationary diffusion flame combustion turbines. An analysis of the formaldehyde emissions data shows that uncontrolled formaldehyde emissions from stationary lean premix combustion turbines are comparable to controlled formaldehyde emissions from stationary diffusion flame combustion turbines controlled with oxidation catalyst systems. Due to the difference in the two technologies, we decided to establish subcategories for diffusion flame and lean premix stationary combustion turbines.

We identified emergency stationary combustion turbines as a subcategory. Emergency stationary combustion turbines operate only in emergencies, such as a loss of power provided by another source. These types of stationary combustion turbines operate infrequently and, when called upon to operate, must respond without failure and without lengthy periods of startup. These conditions limit the applicability of HAP emission control technology to emergency stationary combustion turbines.

Limited use stationary combustion turbines were also identified as a subcategory. These types of stationary combustion turbines are operated 50 hours per calendar year or less. They are used primarily to stabilize electrical power voltage levels during periods of brown outs to prevent damage to sensitive electronic equipment. As with emergency stationary combustion turbines, they are operated infrequently and, when called upon to operate, must respond without failure and without lengthy periods of startup. These conditions limit the applicability of HAP emission control technology.

Similarly, stationary combustion turbines which fire landfill gas or digester gas as their primary fuel were identified as a subcategory. Landfill and digester gases contain a family of chemicals referred to as siloxanes, which limit the application of HAP emission control technology.

Stationary combustion turbines of less than 1 MW rated peak power output were also identified as a subcategory. We believe these small stationary combustion turbines are few in number and, to our knowledge, none use emission control technology to reduce HAP. Given the very small size of these stationary combustion turbines and the lack of application of HAP emission control technologies, we have concerns about the applicability of HAP emission control technology to them. B. What About Stationary Combustion Turbines Located at Area Sources?

The proposed rule does not apply to stationary combustion turbines located at an area source of HAP emissions. In developing our Urban Air Toxics Strategy, we identified area sources we believe warrant regulation to protect the environment and the public health and satisfy the statutory requirements in section 112 of the CAA pertaining to area sources. Stationary combustion turbines located at area sources were not included on that list. As a result, the proposed rule does not apply to these stationary combustion turbines.

C. What Is the Affected Source?

The proposed rule applies to any stationary combustion turbine located at a major source. Consequently, stationary combustion turbines located at major sources of HAP emissions are the affected source under the proposed rule.
D. How Did We Determine the Basis and Level of the Proposed Emission Limitations for Existing Sources?

As established in section 112 of the CAA, the MACT standards must be no less stringent than the MACT floor. The MACT floor for existing sources is the average emission limitation achieved by the best performing 12 percent of existing sources.
1. MACT Floor for Existing Diffusion Flame Combustion Turbines

To determine the MACT floor for existing stationary diffusion flame combustion turbines, we primarily consulted two databases: an inventory database and an emissions database. The MACT floors and MACT for stationary diffusion flame combustion turbines located at major sources were developed through the analyses of these databases.

The inventory database provides population information on stationary combustion turbines in the United States (U.S.) and was constructed in order to support the proposed rulemaking. Data in the inventory database are based on information from available databases, such as the Aerometric Information Retrieval System (AIRS), the Ozone Transport and Assessment Group (OTAG), and State and local agencies' databases. The first version of the database was released in 1997. Subsequent versions have been released reflecting additional or updated data. The most recent release of the database is version 4, released in November 1998.

The inventory database contains information on approximately 4,800 stationary combustion turbines. The current stationary combustion turbine population is estimated to be about 8,000 turbines. Therefore, the inventory database represents about 60 percent of the stationary combustion turbines in the U.S. At least 90 percent of those turbines are assumed to be diffusion flame combustion turbines, based on [[Page 1896]]

conversations with turbine manufacturers.

The information contained in the inventory database is believed to be representative of stationary combustion turbines primarily because of its comprehensiveness. The database includes both small and large stationary combustion turbines in different user segments. Fortyeight percent are ``industrial,'' 39 percent are ``utility,'' and 13 percent are ``pipeline.'' Note that independent power producers (IPP) are included in the utility and industrial segments.

We examined the inventory database for information on HAP emission control technology. There were no turbines controlled with oxidation catalyst systems in the inventory database so we used information supplied by catalyst vendors. There are about 200 oxidation catalyst systems installed in the U.S. The only control technology currently proven to reduce HAP emissions from stationary diffusion flame combustion turbines is an oxidation catalyst emission control device, such as a CO oxidation catalyst. These control devices are used to reduce CO emissions and are currently installed on several stationary combustion turbines. However, less than 3 percent of existing stationary diffusion flame combustion turbines in the U.S., based on information in our inventory database and information from catalyst vendors, are equipped with oxidation catalyst emission control devices; thus, the average of the best performing 12 percent of existing diffusion flame combustion turbines is no HAP emissions reductions.

We also investigated the use of good operating practices for stationary diffusion flame combustion turbines to determine if the use of such practices might identify a MACT floor. There are no references in the inventory database to good operating practices for any stationary combustion turbines.

Most stationary diffusion flame combustion turbines will not operate unless preset conditions established by the manufacturer are met. Stationary diffusion flame combustion turbines, by manufacturer design, permit little operator involvement and there are no operating parameters, such as air/fuel ratio, for the operator to adjust. We concluded, therefore, that there are no specific good operating practices which could reduce HAP emissions or which could serve to identify a MACT floor.

We also investigated switching fuels in existing diffusion flame combustion turbines using fuels which result in higher HAP emissions with fuels that result in lower HAP emissions. When we compared the HAP emissions of the various fuels from combustion turbines using the April 2000 revision of Chapter 3.1 (Stationary Gas Turbines) of ``Compilation of Air Pollutant Emission Factors AP42, Fifth Edition, Volume 1: Stationary Point and Area Sources,'' we could not find a fuel that was clearly less HAP emitting. The summation of emission factors for various HAP when using natural gas (usually considered the cleanest fuel), diesel fuel, landfill, or digester gas were comparable based on the emission factor information that is available. Therefore, we could not identify a MACT floor based on use of a particular fuel.

Another approach we investigated to identify a MACT floor was to review the requirements in existing State regulations and permits. No State regulations exist for HAP emission limits for stationary combustion turbines. Only one State permit limitation for a single HAP (benzene) was identified. Therefore, we were unable to use State regulations or permits to identify a MACT floor.

As a result, we concluded the MACT floor for existing stationary diffusion flame combustion turbines is no emissions reductions. 2. MACT for Existing Diffusion Flame Combustion Turbines

To determine MACT for existing stationary diffusion flame combustion turbines, we evaluated regulatory alternatives more stringent than the MACT floor. For existing diffusion flame sources, in terms of an emission control technology which could serve as the basis for MACT, we considered two beyondthefloor options. The first option considered was the use of an oxidation catalyst emission control device. However, we concluded that the incremental cost per ton of HAP removed for this option is excessive.

The incremental cost per ton is the difference in annual costs between this regulatory option and the MACT floor divided by the difference in annual emissions. It is often used as a measure of the economic feasibility of applying emission control technology to a source.

We also considered the nonair health, environmental, and energy impacts of an oxidation catalyst system, as discussed previously in this preamble, and concluded that there would be only a small energy impact and no nonair health or environmental impacts. However, as stated above, we did not adopt this regulatory option due to cost considerations.

The second option considered was to switch fuels in existing turbines using fuels which result in higher HAP emissions with fuels that result in lower HAP emissions. As stated above, we could not find a fuel that was clearly less HAP emitting. Therefore, we could find no basis to further consider fuel switching as a beyondthefloor HAP emissions reductions option. We were unable to identify any other beyondthefloor regulatory option to consider. As discussed above, we are not aware of any specific good operating practices for diffusion flame turbines that could reduce HAP emissions. As a result, we concluded that MACT for existing diffusion flame combustion turbines is the MACT floor (i.e., no emissions reductions).

3. MACT Floor for Existing Lean Premix Combustion Turbines

There are an estimated 800 lean premix combustion turbines in the U.S., of which 160 are estimated to be major sources. For existing lean premix combustion turbines, we must establish a MACT floor which represents the average emission limitation achieved by the best performing 12 percent of the existing sources for which we have emissions information. We have emissions information on five existing lean premix combustion turbines. Therefore, we plan to establish the MACT floor based on the performance of the best performing lean premix combustion turbine. (This best performing turbine represents the top 20 percent of the existing turbines for which we have emissions information and will also be used to establish the MACT floor for new lean premix combustion turbines.) The best performing existing lean premix combustion turbine achieved a level of formaldehyde concentration emission which averaged 6.1 parts per billion (ppb) formaldehyde at 15 percent oxygen (O2). This is the best performer out of five lean premix combustion turbine tests for which we have data. The threerun average formaldehyde emissions from these five turbines ranged from 6.1 to 41 ppb formaldehyde. The formaldehyde concentrations for the individual runs for the best performing turbine were 5.1 ppb, 5.7 ppb, and 7.7 ppb.

The test method that was used to measure the emissions from the best performing turbine was California Air Resources Board (CARB) Method 430. We do not believe that the MACT emission limit should be set lower than the limit of detection of the method. If it were, we could not determine whether a source with test results at the limit of detection was actually in compliance with the MACT emission limit. For the test runs on the best
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performing turbine, we determined that the method had a minimum detection level (MDL) of between 2 and 3 ppb formaldehyde. We expect the MDL to vary somewhat in actual practice and, thus, do not assume that the MDL would be the same if the method were run by another person or at another laboratory. We have no information regarding the distribution of the CARB Method 430 MDL actually achieved by other testers. We want to ensure that the MACT floor reflects the variability in the limit of detection determined by different, competent testers throughout the U.S. using the same method, i.e., CARB Method 430. We only have one test, the test conducted on the best performing turbine, to try to determine a limit of detection for this method, and this is not enough information to determine the variability in the limit of detection among different testers. If we had sufficient information on the limit of detection determined by different competent testers using Method 430, under similar conditions, we would analyze the results to determine the average limit of detection and its standard deviation. To establish a limit of detection that would be achievable by approximately 99 percent of all the testers, we would add three times the standard deviation to the average limit of detection. Since we do not have this information, we can attempt to estimate it. We believe that it is reasonable to assume that the standard deviation of the limit of detection is no greater than the single estimate of the limit that we have. If we multiply the single value of the limit of detection by three and add it to itself, the result is an estimate of the upper bound for the limit of detection that is four times the single measured value that we have. Based on the considerations above, the lowest MACT floor that we believe would take into account the variability in the MDL is 12 ppb. This level provides a safety factor of four to account for uncertainty in whether testers could routinely achieve a limit of detection of 2 to 3 ppb formaldehyde.

The combustion turbine MACT would be a national standard, and therefore, the MACT limit should reflect variations in the performance of the best performing turbine that could occur. There are two major sources of variability that together produce the total variability observed in the emissions sample results. These sources of variability are: the actual variability in the emissions, and the variability associated with procedures for sampling and analyzing the emissions samples. We believe there is substantial basis to conclude that sources of variability unrelated to turbine performance account for the differences in formaldehyde emissions concentrations between the five turbines. We discuss these sources of variability in more detail below.

When we began investigating the possible sources of the actual (nonsampling, nonanalytical) variability in lean premix combustion turbine emissions, we realized that turbine performance was only one of several possible sources of that variability, and that turbine emissions also could vary widely due to environmental and operational factors that are unrelated to turbine performance and that are beyond an operator's control.

Specifically, formaldehyde concentrations are expected to vary temporally (e.g., seasonally) and spatially (e.g., geographically) due to environmental and operational factors such as temperature, humidity, atmospheric pressure, fuel quality, and the concentrations of formaldehyde present in the ambient air. It is our judgement that if the turbines were tested at various times during the year and at various locations throughout the U.S., the concentration of formaldehyde emitted by a given turbine could vary by a factor of seven or more, solely due to geographic and temporal differences in temperature, humidity, atmospheric pressure, fuel quality, and formaldehyde concentration in the ambient air. This factor is based not only on the short term variability of the data

FOR FURTHER INFORMATION CONTACT Mr. Sims Roy, Combustion Group, Emission Standards Division (MDC43901), U.S. EPA, Research Triangle Park, North Carolina 27711; telephone number (919) 5415263; facsimile number (919) 5415450; electronic mail address roy.sims@epa.gov.