Document ID: EPA-HQ-OAR-2018-0833-0001
Agency: epa
Document Type: Proposed Rule
Title: National Emission Standards for Hazardous Air Pollutants: Site Remediation Residual Risk and Technology Review
Posted Date: 2019-09-03T04:00Z

[Federal Register Volume 84, Number 170 (Tuesday, September 3, 2019)]
[Proposed Rules]
[Pages 46138-46182]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-17223]

[[Page 46137]]

Vol. 84

Tuesday,

No. 170

September 3, 2019

Part III

 Environmental Protection Agency

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40 CFR Part 63

 National Emission Standards for Hazardous Air Pollutants: Site 
Remediation Residual Risk and Technology Review; Proposed Rule

  Federal Register / Vol. 84 , No. 170 / Tuesday, September 3, 2019 / 
Proposed Rules  

[[Page 46138]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2018-0833; FRL-9998-13-OAR]
RIN 2060-AU19

National Emission Standards for Hazardous Air Pollutants: Site 
Remediation Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing 
amendments to the National Emission Standards for Hazardous Air 
Pollutants (NESHAP) for the Site Remediation source category. This 
proposal presents the results of the residual risk and technology 
review (RTR) conducted as required under the Clean Air Act (CAA). Based 
on the results of the residual risk review, the EPA is proposing that 
risks due to emissions of air toxics are acceptable and that no 
revision to the standards is required to provide an ample margin of 
safety to protect public health. Based on the technology review, we are 
proposing to amend the requirements for leak detection and repair 
(LDAR). In addition, the EPA is proposing amendments to revise 
regulatory provisions pertaining to emissions during periods of 
startup, shutdown and malfunction (SSM), including adding requirements 
for pressure relief devices; to add requirements for electronic 
submittal of semiannual reports and performance test results; to 
clarify provisions pertaining to open-ended valves and lines; and to 
make minor clarifications and corrections. The proposed revisions to 
the rule would increase the level of emissions control and 
environmental protection provided by the Site Remediation NESHAP. We 
are also requesting additional comment related to subcategorization of 
sources relating to certain exemption provisions of the original rule 
that were proposed for removal in 2016.

DATES: 
    Comments. Comments must be received on or before October 18, 2019. 
Under the Paperwork Reduction Act (PRA), comments on the information 
collection provisions are best assured of consideration if the Office 
of Management and Budget (OMB) receives a copy of your comments on or 
before October 3, 2019.
    Public hearing. If anyone contacts us requesting a public hearing 
on or before September 9, 2019, we will hold a hearing. Additional 
information about the hearing, if requested, will be published in a 
subsequent Federal Register document and posted at https://www.epa.gov/stationary-sources-air-pollution/site-remediation-national-emission-standards-hazardous-air. See SUPPLEMENTARY INFORMATION for information 
on requesting and registering for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2018-0833, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/ 
(our preferred method). Follow the online instructions for submitting 
comments.
     Email: a-and-r-docket@epa.gov. Include Docket ID No. EPA-
HQ-OAR-2018-0833 in the subject line of the message.
     Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-
2018-0833.
     Mail: U.S. Environmental Protection Agency, EPA Docket 
Center, Docket ID No. EPA-HQ-OAR-2018-0833, Mail Code 28221T, 1200 
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West 
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. 
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except Federal holidays).
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received may be posted without change 
to https://www.regulations.gov/, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the SUPPLEMENTARY 
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed 
action, contact Matthew Witosky, Sector Policies and Programs Division 
(E143-05), Office of Air Quality Planning and Standards, U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711; telephone number: (919) 541-2865; fax number: (919) 541-0516; 
and email address: witosky.matthew@epa.gov. For specific information 
regarding the risk modeling methodology, contact Matthew Woody, Health 
and Environmental Impacts Division (C539-02), Office of Air Quality 
Planning and Standards, U.S. Environmental Protection Agency, Research 
Triangle Park, North Carolina 27711; telephone number: (919) 541-1535; 
fax number: (919) 541-0840; and email address: woody.matthew@epa.gov. 
For questions about monitoring and testing requirements, contact 
Theresa Lowe, Sector Policies and Programs Division (D143-05), Office 
of Air Quality Planning and Standards, U.S. Environmental Protection 
Agency, Research Triangle Park, North Carolina 27711; telephone number 
(919) 541-4786; fax number: (919) 541-4991; and email address: 
Lowe.Theresa@epa.gov. For information about the applicability of the 
NESHAP to a particular entity, contact Marcia Mia, Office of 
Enforcement and Compliance Assurance, U.S. Environmental Protection 
Agency, WJC South Building (Mail Code 2227A), 1200 Pennsylvania Avenue 
NW, Washington, DC 20460; telephone number: (202) 564-7042; and email 
address: Mia.Marcia@epa.gov.

SUPPLEMENTARY INFORMATION: 
    Public hearing. Please contact Virginia Hunt at (919) 541-0832 or 
by email at hunt.virginia@epa.gov to request a public hearing, to 
register to speak at the public hearing, or to inquire as to whether a 
public hearing will be held.
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2018-0833. All documents in the docket are 
listed in Regulations.gov. Although listed, some information is not 
publicly available, e.g., CBI (Confidential Business Information) or 
other information whose disclosure is restricted by statute. Certain 
other material, such as copyrighted material, is not placed on the 
internet and will be publicly available only in hard copy. Publicly 
available docket materials are available either electronically in 
Regulations.gov or in hard copy at the EPA Docket Center, Room 3334, 
WJC West Building, 1301 Constitution Avenue 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.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2018-0833. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at https://www.regulations.gov/, including any personal 
information provided, unless the comment includes information claimed 
to be CBI or other information whose disclosure is restricted by 
statute.

[[Page 46139]]

Do not submit information that you consider to be CBI or otherwise 
protected through https://www.regulations.gov/ or email. This type of 
information should be submitted by mail as discussed below.
    The EPA may publish any comment received to its public docket. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the Web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit https://www2.epa.gov/dockets/commenting-epa-dockets.
    The https://www.regulations.gov/ website allows you to submit your 
comment anonymously, which means the EPA will not know your identity or 
contact information unless you provide it in the body of your comment. 
If you send an email comment directly to the EPA without going through 
https://www.regulations.gov/, your email 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, the EPA recommends that you include your name and 
other contact information in the body of your comment and with any 
digital storage media you submit. If the EPA cannot read your comment 
due to technical difficulties and cannot contact you for clarification, 
the EPA may not be able to consider your comment. Electronic files 
should not include special characters or any form of encryption and be 
free of any defects or viruses. For additional information about the 
EPA's public docket, visit the EPA Docket Center homepage at https://www.epa.gov/dockets.
    The EPA is soliciting comment on numerous aspects of the proposed 
rule. The EPA has indexed each comment solicitation with an alpha-
numeric identifier (e.g., ``C-1,'' ``C-2,'' ``C-3'') to provide a 
consistent framework for effective and efficient provision of comments. 
Accordingly, the EPA asks that commenters include the identifier in 
either a heading, or within the text of each comment (e.g., ``In 
response to solicitation of comment C-1, . . .'') to make clear which 
comment solicitation is being addressed. The EPA emphasizes that the 
Agency is not limiting comment to these identified areas and encourages 
provision of any other comments on topics within the scope of this 
proposal.
    Submitting CBI. Do not submit information containing CBI to the EPA 
through https://www.regulations.gov/ or email. Clearly mark the part or 
all of the information that you claim to be CBI. For CBI information on 
any digital storage media that you mail to the EPA, mark the outside of 
the digital storage media as CBI and then identify electronically 
within the digital storage media the specific information that is 
claimed as CBI. In addition to one complete version of the comments 
that includes information claimed as CBI, you must submit a copy of the 
comments that does not contain the information claimed as CBI directly 
to the public docket through the procedures outlined in Instructions 
above. If you submit any digital storage media that does not contain 
CBI, mark the outside of the digital storage media clearly that it does 
not contain CBI. Information not marked as CBI will be included in the 
public docket and the EPA's electronic public docket without prior 
notice. Information marked as CBI will not be disclosed except in 
accordance with procedures set forth in 40 Code of Federal Regulations 
(CFR) part 2. Send or deliver information identified as CBI only to the 
following address: OAQPS Document Control Officer (C404-02), OAQPS, 
U.S. Environmental Protection Agency, Research Triangle Park, North 
Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2018-0833.
    Preamble acronyms and abbreviations. We use multiple acronyms and 
terms in this preamble. While this list may not be exhaustive, to ease 
the reading of this preamble and for reference purposes, the EPA 
defines the following terms and acronyms here:

AEGL acute exposure guideline level
AERMOD air dispersion model used by the HEM-3 model
BACT best available control technology
CAA Clean Air Act
CalEPA California EPA
CBI Confidential Business Information
CFR Code of Federal Regulations
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guideline
ERT Electronic Reporting Tool
GACT generally achievable control technology
HAP hazardous air pollutant(s)
HCl hydrochloric acid
HEM-3 Human Exposure Model
HF hydrogen fluoride
HI hazard index
HQ hazard quotient
IRIS Integrated Risk Information System
km kilometer
LAER lowest achievable emission rate
MACT maximum achievable control technology
mg/kg-day milligrams per kilogram per day
mg/m\3\ milligrams per cubic meter
MIR maximum individual risk
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
NRC National Research Council
NSR New Source Review
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OECA Office of Enforcement and Compliance Assurance
OMB Office of Management and Budget
PAH polycyclic aromatic hydrocarbons
PB-HAP hazardous air pollutants known to be persistent and bio-
accumulative in the environment
PM particulate matter
POM polycyclic organic matter
ppm parts per million
RACT reasonably available control technology
RBLC RACT/BACT/LAER clearinghouse
REL reference exposure level
RFA Regulatory Flexibility Act
RfC reference concentration
RfD reference dose
RTR residual risk and technology review
SAB Science Advisory Board
SBA Small Business Administration
SIC Standard Industrial Classification
SSM startup, shutdown, and malfunction
TOSHI target organ-specific hazard index
tpy tons per year
TRIM.FaTE Total Risk Integrated Methodology.Fate, Transport, and 
Ecological Exposure model
UF uncertainty factor
[micro]g/m\3\ microgram per cubic meter
UMRA Unfunded Mandates Reform Act
URE unit risk estimate
VCS voluntary consensus standards

    Organization of this document. The information in this preamble is 
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related 
information?
II. Background
    A. What is the statutory authority for this action?
    B. What is this source category?
    C. What data collection activities were conducted to support 
this action?
    D. What other relevant background information and data are 
available?
III. Analytical Procedures and Decision-Making
    A. How do we consider risk in our decision-making?
    B. How do we perform the technology review?
    C. How do we estimate post-MACT risk posed by the source 
category?
IV. Analytical Results and Proposed Decisions

[[Page 46140]]

    A. What actions are we taking pursuant to CAA sections 112(d)(2) 
and 112(d)(3)?
    B. What are the results of the risk assessment and analyses for 
affected sources?
    C. What are our proposed decisions regarding risk acceptability, 
ample margin of safety, and adverse environmental effect?
    D. Additional Modeling for Site Remediation
    E. What are the results and proposed decisions based on our 
technology review?
    F. What other actions are we proposing?
    G. What compliance dates are we proposing?
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
VI. Request for Comment
    A. Request for Comment Regarding CERCLA/RCRA Exempt Sources
    B. Request for Comment on all Aspects of the Risk and Technology 
Review
VII. Submitting Data Corrections
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulation and Controlling 
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act (NTTAA) and 
1 CFR Part 51
    K. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations

I. General Information

A. Does this action apply to me?

    Table 1 of this preamble lists the NESHAP and associated regulated 
industrial source category that is the subject of this proposal. Table 
1 is not intended to be exhaustive, but rather provides a guide for 
readers regarding the entities that this proposed action is likely to 
affect. The proposed standards, once promulgated, will be directly 
applicable to the affected sources. Federal, state, local, and tribal 
government entities conducting site remediations subject to the Site 
Remediation NESHAP may be affected by this proposed action. As defined 
in the Initial List of Categories of Sources Under Section 112(c)(1) of 
the Clean Air Act Amendments of 1990 (see 57 FR 31576, July 16, 1992) 
and Documentation for Developing the Initial Source Category List, 
Final Report (see EPA-450/3-91-030, July 1992), the Site Remediation 
source category is any facility engaged in the cleanup of sites that 
possess contaminated media. Sites undergoing remediation of 
contaminated media include, but are not limited to, any facility at 
which organic materials currently are or have been in the past stored, 
processed, treated, or otherwise managed at the facility. These 
facilities include organic liquid storage terminals, petroleum 
refineries, chemical manufacturing facilities, and other manufacturing 
facilities with collocated site remediation activities. Units requiring 
cleanup can include hazardous waste dumps, industrial surface 
impoundments, leaking tanks, and municipal, industrial, and combined 
landfills. Site remediation includes, but is not limited to, the 
following activities: Contaminated soils cleaning; soil vapor 
extraction (SVE); groundwater cleanup; oil recovery from below ground; 
surface flow control; waste material removal from the site; treatment 
of waste material after removal; and cleansing of water mains, sewers, 
wetlands, and water bodies that have been contaminated by wastes. Site 
remediation does not include the installation of controls to municipal 
solid waste landfills to comply with the new source performance 
standards or Clean Air Act (CAA) section 111(d) emission guidelines.

    Table 1--NESHAP and Industrial Source Categories Affected by This
                             Proposed Action
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        Source category               NESHAP           NAICS code \1\
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Industry......................  40 CFR part 63,    325211, 325192,
                                 subpart GGGGG.     325188, 32411,
                                                    49311, 49319, 48611,
                                                    42269, 42271.
Federal Government............  .................  Federal agency
                                                    facilities that
                                                    conduct site
                                                    remediation
                                                    activities.
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\1\ North American Industry Classification System.

B. Where can I get a copy of this document and other related 
information?

    In addition to being available in the docket, an electronic copy of 
this action is available on the internet. Following signature by the 
EPA Administrator, the EPA will post a copy of this proposed action at 
https://www.epa.gov/stationary-sources-air-pollution/site-remediation-national-emission-standards-hazardous-air. Following publication in the 
Federal Register, the EPA will post the Federal Register version of the 
proposal and key technical documents at this same website. Information 
on the overall RTR program is available at https://www3.epa.gov/ttn/atw/rrisk/rtpg.html.
    A redline version of the regulatory language that incorporates the 
proposed changes in this action is available in the docket for this 
action (Docket ID No. EPA-HQ-OAR-2018-0833).

II. Background

A. What is the statutory authority for this action?

    The statutory authority for this action is provided by sections 112 
and 301 of the CAA, as amended (42 U.S.C. 7401 et seq.). Section 112 of 
the CAA establishes a two-stage regulatory process to develop standards 
for emissions of hazardous air pollutants (HAP) from stationary 
sources. Generally, the first stage involves establishing technology-
based standards and the second stage involves evaluating those 
standards that are based on maximum achievable control technology 
(MACT) to determine whether additional standards are needed to address 
any remaining risk associated with HAP emissions. This second stage is 
commonly referred to as the ``residual risk review.'' In addition to 
the residual risk review, the CAA also requires the EPA to review 
standards set under CAA section 112 every 8 years to determine if there 
are ``developments in practices, processes, or control technologies'' 
that may be appropriate

[[Page 46141]]

to incorporate into the standards. This review is commonly referred to 
as the ``technology review.'' When the two reviews are combined into a 
single rulemaking, it is commonly referred to as the ``risk and 
technology review.'' The discussion that follows identifies the most 
relevant statutory sections and briefly explains the contours of the 
methodology used to implement these statutory requirements. A more 
comprehensive discussion appears in the document titled CAA Section 112 
Risk and Technology Reviews: Statutory Authority and Methodology, in 
the docket for this rulemaking.
    In the first stage of the CAA section 112 standard setting process, 
the EPA promulgates technology-based standards under CAA section 112(d) 
for categories of sources identified as emitting one or more of the HAP 
listed in CAA section 112(b). Sources of HAP emissions are either major 
sources or area sources, and CAA section 112 establishes different 
requirements for major source standards and area source standards. 
``Major sources'' are those that emit or have the potential to emit 10 
tons per year (tpy) or more of a single HAP or 25 tpy or more of any 
combination of HAP. All other sources are ``area sources.'' For major 
sources, CAA section 112(d)(2) provides that the technology-based 
NESHAP must reflect the maximum degree of emission reductions of HAP 
achievable (after considering cost, energy requirements, and non-air 
quality health and environmental impacts). These standards are commonly 
referred to as MACT standards. CAA section 112(d)(3) also establishes a 
minimum control level for MACT standards, known as the MACT ``floor.'' 
The EPA must also consider control options that are more stringent than 
the floor. Standards more stringent than the floor are commonly 
referred to as beyond-the-floor standards. In certain instances, as 
provided in CAA section 112(h), the EPA may set work practice standards 
where it is not feasible to prescribe or enforce a numerical emission 
standard. For area sources, CAA section 112(d)(5) gives the EPA 
discretion to set standards based on generally available control 
technologies or management practices (GACT standards) in lieu of MACT 
standards.
    The second stage in standard-setting focuses on identifying and 
addressing any remaining (i.e., ``residual'') risk according to CAA 
section 112(f). For source categories subject to MACT standards, 
section 112(f)(2) of the CAA requires the EPA to determine whether 
promulgation of additional standards is needed to provide an ample 
margin of safety to protect public health or to prevent an adverse 
environmental effect. Section 112(d)(5) of the CAA provides that this 
residual risk review is not required for categories of area sources 
subject to GACT standards. Section 112(f)(2)(B) of the CAA further 
expressly preserves the EPA's use of the two-step approach for 
developing standards to address any residual risk and the Agency's 
interpretation of ``ample margin of safety'' developed in the National 
Emissions Standards for Hazardous Air Pollutants: Benzene Emissions 
from Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene 
Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery 
Plants (Benzene NESHAP) (54 FR 38044, September 14, 1989). The EPA 
notified Congress in the Risk Report that the Agency intended to use 
the Benzene NESHAP approach in making CAA section 112(f) residual risk 
determinations (EPA-453/R-99-001, p. ES-11). The EPA subsequently 
adopted this approach in its residual risk determinations and the 
United States Court of Appeals for the District of Columbia Circuit 
(the Court) upheld the EPA's interpretation that CAA section 112(f)(2) 
incorporates the approach established in the Benzene NESHAP. See 
Natural Resources Defense Council (NRDC) v. EPA, 529 F.3d 1077, 1083 
(D.C. Cir. 2008).
    The approach incorporated into the CAA and used by the EPA to 
evaluate residual risk and to develop standards under CAA section 
112(f)(2) is a two-step approach. In the first step, the EPA determines 
whether risks are acceptable. This determination ``considers all health 
information, including risk estimation uncertainty, and includes a 
presumptive limit on maximum individual lifetime [cancer] risk (MIR) 
\1\ of approximately 1 in 10 thousand.'' 54 FR 38045, September 14, 
1989. If risks are unacceptable, the EPA must determine the emissions 
standards necessary to reduce risk to an acceptable level without 
considering costs. In the second step of the approach, the EPA 
considers whether the emissions standards provide an ample margin of 
safety to protect public health ``in consideration of all health 
information, including the number of persons at risk levels higher than 
approximately 1 in 1 million, as well as other relevant factors, 
including costs and economic impacts, technological feasibility, and 
other factors relevant to each particular decision.'' Id. The EPA must 
promulgate emission standards necessary to provide an ample margin of 
safety to protect public health. After conducting the ample margin of 
safety analysis, we consider whether a more stringent standard is 
necessary to prevent, taking into consideration costs, energy, safety, 
and other relevant factors, an adverse environmental effect.
---------------------------------------------------------------------------

    \1\ Although defined as ``maximum individual risk,'' MIR refers 
only to cancer risk. MIR, one metric for assessing cancer risk, is 
the estimated risk if an individual were exposed to the maximum 
level of a pollutant for a lifetime.
---------------------------------------------------------------------------

    CAA section 112(d)(6) separately requires the EPA to review 
standards promulgated under CAA section 112 and revise them ``as 
necessary (taking into account developments in practices, processes, 
and control technologies)'' no less often than every 8 years. In 
conducting this review, which we call the ``technology review,'' the 
EPA is not required to recalculate the MACT floor. NRDC v. EPA, 529 
F.3d 1077, 1084 (D.C. Cir. 2008). Association of Battery Recyclers, 
Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 2013). The EPA may consider cost 
in deciding whether to revise the standards pursuant to CAA section 
112(d)(6).

B. What is this source category?

    The EPA promulgated the final Site Remediation NESHAP at 40 CFR 
part 63, subpart GGGGG on October 8, 2003. The NESHAP applies to 
``remediation material.'' Site remediation means one or more activities 
or processes used to remove, destroy, degrade, transform, immobilize, 
or otherwise manage remediation material. Monitoring or measuring of 
contamination levels in media, whether by using wells, sampling, or 
other means, is not considered to be a site remediation. The rule 
applies only to active remedial operations at sites that are major 
sources with affected facilities subject to another MACT standard. The 
Site Remediation NESHAP applies to various types of affected sources 
including process vents, remediation material management units, and 
equipment leaks. The affected source for process vents is the entire 
group of process vents associated with the in-situ and ex-situ 
remediation processes used at the site to remove, destroy, degrade, 
transform, or immobilize hazardous substances in the remediation 
material. Examples of process vents for in-situ remediation processes 
include the discharge vents to the atmosphere used for SVE and 
underground bioremediation processes. Examples of process vents for ex-
situ remediation processes include vents for thermal desorption, 
bioremediation, and stripping processes (air or steam stripping). The 
affected source for remediation material management units is the entire 
group of tanks, surface

[[Page 46142]]

impoundments, containers, oil-water separators, and transfer systems 
used for the site remediation activities involving clean-up of 
remediation material. The affected source for equipment leaks is the 
entire group of remediation equipment components (pumps, valves, etc.) 
that is intended to operate for 300 hours or more during a calendar 
year in remediation material service and that contains or contacts 
remediation material having a concentration of regulated HAP equal to 
or greater than 10 percent by weight.
    The Site Remediation MACT standards include a combination of 
equipment standards, work practice standards, operational standards, 
and performance standards for each of the affected emission sources 
noted above.

C. What data collection activities were conducted to support this 
action?

    The primary sources of data for the risk assessment are EPA 
databases. These include the EPA's Enforcement and Compliance History 
Online (ECHO) database, which was queried to identify facilities 
potentially subject to the Site Remediation NESHAP. Information from 
this search was then used in a query of the EPA's National Emissions 
Inventory (NEI) to identify site remediation emission sources, 
quantities of emissions, and emissions release characteristics. The EPA 
also reviewed the Toxic Release Inventory to determine whether that 
data would be useful in supplementing the information extracted from 
the NEI.
    We reviewed a variety of data sources in our investigation of 
potential practices, processes, or controls to consider in the 
technology review and to provide further information for the risk 
assessment. These included the Reasonably Available Control Technology 
(RACT)/Best Available Control Technology (BACT)/Lowest Achievable 
Emission Rate (LAER) Clearinghouse (RBLC), NESHAP for various 
industries that were promulgated since the Site Remediation NESHAP was 
promulgated, major source operating permits, minor and synthetic minor 
source operating permits, and academic and trade literature.
    The RBLC provides a central database of air pollution control 
technology information and can help identify appropriate technologies 
to mitigate most air pollutant emission streams: https://www.epa.gov/catc/ractbactlaer-clearinghouse-rblc-basic-information. As site 
remediation may include sources from any industrial activity, we 
searched the RBLC with a focus on control of off-gasses in disparate 
applications, including processes in three broad categories: 
Miscellaneous Combustion, Waste Combustion and Waste Disposal, and 
Other Waste Processing and Disposal. Each of these three categories was 
further searched more specifically. For Miscellaneous Combustion, the 
EPA searched emission control afterburners and incinerators, digester 
and landfill gas flares, and other miscellaneous combustion. For Waste 
Combustion and Waste Disposal categories, the search included mixed/
other waste combustion/incineration. Finally, the search under Other 
Waste Processing and Disposal included contaminated soil treatment, 
hazardous waste treatment, storage, and disposal facilities, and other 
waste processing and disposal facilities.
    The EPA also reviewed the NESHAP for various industries that were 
promulgated since the Site Remediation NESHAP was promulgated. We 
reviewed the regulatory requirements and/or technical analyses 
associated with these regulatory actions to identify any practices, 
processes, and control technologies considered in these efforts that 
could be applied to emission sources in the Site Remediation source 
category, as well as the costs, non-air impacts, and energy 
implications associated with the use of these technologies.
    The EPA searched available state databases for minor source permits 
and synthetic minor source permits of facilities performing 
remediation. The Technology Review memorandum in the docket lists the 
permits reviewed and summarizes key findings about the remediation 
projects and emissions controls in use. Other scientific literature was 
reviewed for new and novel control technologies in use at site 
remediation sources and similar sources to control volatile organic 
compounds (VOC) and HAP air emissions. Literature for controls in use 
for land farming applications and material extraction activities was 
also reviewed. For a list of material reviewed, see the memorandum, CAA 
section 112(d)(6) Technology Review for the Site Remediation Source 
Category, which is available in the docket for this action.

D. What other relevant background information and data are available?

    Documents from previous rulemakings for the Site Remediation source 
category can be found in the docket under Docket ID No. EPA-HQ-OAR-
2002-0021.

III. Analytical Procedures and Decision-Making

    In this section, we describe the analyses performed to support the 
proposed decisions for the RTR and other issues addressed in this 
proposal.

A. How do we consider risk in our decision-making?

    As discussed in section II.A of this preamble and in the Benzene 
NESHAP, in evaluating and developing standards under CAA section 
112(f)(2), we apply a two-step approach to determine whether or not 
risks are acceptable and to determine if the standards provide an ample 
margin of safety to protect public health. As explained in the Benzene 
NESHAP, ``the first step judgment on acceptability cannot be reduced to 
any single factor'' and, thus, ``[t]he Administrator believes that the 
acceptability of risk under section 112 is best judged on the basis of 
a broad set of health risk measures and information.'' 54 FR 38046, 
September 14, 1989. Similarly, with regard to the ample margin of 
safety determination, ``the Agency again considers all of the health 
risk and other health information considered in the first step. Beyond 
that information, additional factors relating to the appropriate level 
of control will also be considered, including cost and economic impacts 
of controls, technological feasibility, uncertainties, and any other 
relevant factors.'' Id.
    The Benzene NESHAP approach provides flexibility regarding factors 
the EPA may consider in making determinations and how the EPA may weigh 
those factors for each source category. The EPA conducts a risk 
assessment that provides estimates of the MIR posed by the HAP 
emissions from each source in the source category, the hazard index 
(HI) for chronic exposures to HAP with the potential to cause noncancer 
health effects, and the hazard quotient (HQ) for acute exposures to HAP 
with the potential to cause noncancer health effects.\2\ The assessment 
also provides estimates of the distribution of cancer risk within the 
exposed populations, cancer incidence, and an evaluation of the 
potential for an adverse environmental effect. The scope of the EPA's 
risk analysis is consistent with the EPA's response to comments on our 
policy under the Benzene NESHAP where the EPA explained that:
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    \2\ The MIR is defined as the cancer risk associated with a 
lifetime of exposure at the highest concentration of HAP where 
people are likely to live. The HQ is the ratio of the potential 
exposure concentration to the noncancer dose-response value; the HI 
is the sum of HQs for HAP that affect the same target organ or organ 
system.

[[Page 46143]]

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[t]he policy chosen by the Administrator permits consideration of 
multiple measures of health risk. Not only can the MIR figure be 
considered, but also incidence, the presence of noncancer health 
effects, and the uncertainties of the risk estimates. In this way, 
the effect on the most exposed individuals can be reviewed as well 
as the impact on the general public. These factors can then be 
weighed in each individual case. This approach complies with the 
Vinyl Chloride mandate that the Administrator ascertain an 
acceptable level of risk to the public by employing his expertise to 
assess available data. It also complies with the Congressional 
intent behind the CAA, which did not exclude the use of any 
particular measure of public health risk from the EPA's 
consideration with respect to CAA section 112 regulations, and 
thereby implicitly permits consideration of any and all measures of 
health risk which the Administrator, in his judgment, believes are 
appropriate to determining what will `protect the public health'.

See 54 FR 38057, September 14, 1989. Thus, the level of the MIR is only 
one factor to be weighed in determining acceptability of risk. The 
Benzene NESHAP explained that ``an MIR of approximately one in 10 
thousand should ordinarily be the upper end of the range of 
acceptability. As risks increase above this benchmark, they become 
presumptively less acceptable under CAA section 112, and would be 
weighed with the other health risk measures and information in making 
an overall judgment on acceptability. Or, the Agency may find, in a 
particular case, that a risk that includes an MIR less than the 
presumptively acceptable level is unacceptable in the light of other 
health risk factors.'' Id. at 38045. Similarly, with regard to the 
ample margin of safety analysis, the EPA stated in the Benzene NESHAP 
that: ``EPA believes the relative weight of the many factors that can 
be considered in selecting an ample margin of safety can only be 
determined for each specific source category. This occurs mainly 
because technological and economic factors (along with the health-
related factors) vary from source category to source category.'' Id. at 
38061. We also consider the uncertainties associated with the various 
risk analyses, as discussed earlier in this preamble, in our 
determinations of acceptability and ample margin of safety.
    The EPA notes that it has not considered certain health information 
to date in making residual risk determinations. At this time, we do not 
attempt to quantify the HAP risk that may be associated with emissions 
from other facilities that do not include the source category under 
review, mobile source emissions, natural source emissions, persistent 
environmental pollution, or atmospheric transformation in the vicinity 
of the sources in the category.
    The EPA understands the potential importance of considering an 
individual's total exposure to HAP in addition to considering exposure 
to HAP emissions from the source category and facility. We recognize 
that such consideration may be particularly important when assessing 
noncancer risk, where pollutant-specific exposure health reference 
levels (e.g., reference concentrations (RfCs)) are based on the 
assumption that thresholds exist for adverse health effects. For 
example, the EPA recognizes that, although exposures attributable to 
emissions from a source category or facility alone may not indicate the 
potential for increased risk of adverse noncancer health effects in a 
population, the exposures resulting from emissions from the facility in 
combination with emissions from all of the other sources (e.g., other 
facilities) to which an individual is exposed may be sufficient to 
result in an increased risk of adverse noncancer health effects. In May 
2010, the Science Advisory Board (SAB) advised the EPA ``that RTR 
assessments will be most useful to decision makers and communities if 
results are presented in the broader context of aggregate and 
cumulative risks, including background concentrations and contributions 
from other sources in the area.'' \3\
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    \3\ Recommendations of the SAB Risk and Technology Review Panel 
are provided in their report, which is available at: https://
yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
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    In response to the SAB recommendations, the EPA incorporates 
cumulative risk analyses into its RTR risk assessments, including those 
reflected in this proposal. The Agency (1) conducts facility-wide 
assessments, which include source category emission points, as well as 
other emission points within the facilities; (2) combines exposures 
from multiple sources in the same category that could affect the same 
individuals; and (3) for some persistent and bioaccumulative 
pollutants, analyzes the ingestion route of exposure. In addition, the 
RTR risk assessments consider aggregate cancer risk from all 
carcinogens and aggregated noncancer HQs for all noncarcinogens 
affecting the same target organ or target organ system.
    Although we are interested in placing source category and facility-
wide HAP risk in the context of total HAP risk from all sources 
combined in the vicinity of each source, we are concerned about the 
uncertainties of doing so. Estimates of total HAP risk from emission 
sources other than those that we have studied in depth during this RTR 
review would have significantly greater associated uncertainties than 
the source category or facility-wide estimates. Such aggregate or 
cumulative assessments would compound those uncertainties, making the 
assessments too unreliable.

B. How do we perform the technology review?

    Our technology review focuses on the identification and evaluation 
of developments in practices, processes, and control technologies that 
have occurred since the MACT standards were promulgated. Where we 
identify such developments, we analyze their technical feasibility, 
estimated costs, energy implications, and non-air environmental 
impacts. We also consider the emission reductions associated with 
applying each development. This analysis informs our decision of 
whether it is ``necessary'' to revise the emissions standards. In 
addition, we consider the appropriateness of applying controls to new 
sources versus retrofitting existing sources. For this exercise, we 
consider any of the following to be a ``development'':
     Any add-on control technology or other equipment that was 
not identified and considered during development of the original MACT 
standards;
     Any improvements in add-on control technology or other 
equipment (that were identified and considered during development of 
the original MACT standards) that could result in additional emissions 
reduction;
     Any work practice or operational procedure that was not 
identified or considered during development of the original MACT 
standards;
     Any process change or pollution prevention alternative 
that could be broadly applied to the industry and that was not 
identified or considered during development of the original MACT 
standards; and
     Any significant changes in the cost (including cost 
effectiveness) of applying controls (including controls the EPA 
considered during the development of the original MACT standards).
    In addition to reviewing the practices, processes, and control 
technologies that were considered at the time we last updated the 
NESHAP, we review a variety of data sources in our investigation of 
potential practices, processes, or controls to consider. See sections 
II.C and II.D of this preamble for information on the specific data

[[Page 46144]]

sources that were reviewed as part of the technology review.

C. How do we estimate post-MACT risk posed by the source category?

    In this section, we provide a complete description of the types of 
analyses that we generally perform during the risk assessment process. 
In some cases, we do not perform a specific analysis because it is not 
relevant. For example, in the absence of emissions of HAP known to be 
persistent and bioaccumulative in the environment (PB-HAP), we would 
not perform a multipathway exposure assessment. Where we do not perform 
an analysis, we state that we do not and provide the reason. While we 
present all of our risk assessment methods, we only present risk 
assessment results for the analyses actually conducted (see section 
IV.B of this preamble).
    The EPA conducts a risk assessment that provides estimates of the 
MIR for cancer posed by the HAP emissions from each source in the 
source category, the HI for chronic exposures to HAP with the potential 
to cause noncancer health effects, and the HQ for acute exposures to 
HAP with the potential to cause noncancer health effects. The 
assessment also provides estimates of the distribution of cancer risk 
within the exposed populations, cancer incidence, and an evaluation of 
the potential for an adverse environmental effect. The eight sections 
that follow this paragraph describe how we estimated emissions and 
conducted the risk assessment. The docket for this rulemaking contains 
the following document which provides more information on the risk 
assessment inputs and models: Residual Risk Assessment for the Site 
Remediation Source Category in Support of the 2019 Risk and Technology 
Review Proposed Rule. The methods used to assess risk (as described in 
the eight primary steps below) are consistent with those described by 
the EPA in the document reviewed by a panel of the EPA's SAB in 2009; 
\4\ and described in the SAB review report issued in 2010. They are 
also consistent with the key recommendations contained in that report.
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    \4\ U.S. EPA. Risk and Technology Review (RTR) Risk Assessment 
Methodologies: For Review by the EPA's Science Advisory Board with 
Case Studies--MACT I Petroleum Refining Sources and Portland Cement 
Manufacturing. (EPA-452/R-09-006; June 2009.) https://www3.epa.gov/airtoxics/rrisk/rtrpg.html.
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1. How did we estimate actual emissions and identify the emissions 
release characteristics?
a. Sources Subject to the Site Remediation NESHAP
    The EPA began compiling the list of facilities for the risk review 
by searching for facilities identified as being subject to the Site 
Remediation NESHAP in the EPA's ECHO database. There are currently 102 
facilities identified as ``subject to NESHAP GGGGG'' in ECHO. This list 
of facilities was used as the basis for a query into the NEI to obtain 
facility and emissions data for the 2014 reporting year.
    Of the 102 facilities with data retrieved from the 2014 NEI, six 
facilities reported emissions under the Source Classification Code 
(SCC) for site remediation, and 96 reported emissions only from their 
primary activity and did not report any emissions for remediation 
activities. We attribute the absence of site remediation data for these 
96 facilities to either the facilities' completion of site remediation 
activities or reporting of site remediation emissions data under other 
SCCs in the NEI. The EPA chose to model all 102 facilities rather than 
only the six for which remediation data was reported, in order to take 
the broadest possible approach to the risk assessment. For example, 
while a remediation may not have been occuring in 2014 that would be 
reported in the 2014 inventory, the EPA assumed that a remediation 
would have taken place at some point at all 102 facilities since 
adoption of the Site Remediation NESHAP. By including all 102 
facilities, the EPA attempted to estimate the risk of anyone who may 
have been exposed to risk from a remediation at an affected source, 
regardless of the current (as of 2014) status of a specific remediation 
action.
    To address the lack of apparent site remediation emissions data for 
these 96 facilities, the EPA developed a profile of site remediation 
emissions for each facility based on the facility's primary processes. 
Since site remediation projects occur at many different types of 
industrial facilities, ranging from petroleum refineries to federal 
facilities, and the emissions from the site remediation are likely a 
subset of HAP emitted by the facility, this emissions profile approach 
was used to account for the disparate nature of sources with site 
remediation activities. To develop the emission profiles for each 
facility, the EPA used the six facilities that reported HAP emissions 
both from their remediation activities and from their whole facility in 
the NEI and determined the proportion of remediation HAP emissions to 
facility-wide HAP emissions for each facility. Of the six facilities, 
the highest proportion of remediation to whole-facility HAP emissions 
was 0.79 percent. For the other 96 facilities, the EPA used this 
proportion to assign 0.79 percent of the total amount of each HAP 
reported in the NEI for the whole facility to the Site Remediation 
source category for each facility, arriving at a unique profile of site 
remediation emissions for each facility.
    With respect to the risk analysis, the EPA considers this to be a 
conservative approach to addressing the lack of remediation emissions 
reported in the NEI. First, the data show that remediation emissions 
are generally small compared to major source emissions at affected 
facilities, and the highest proportion of remediation emissions from 
the six facilities was chosen for the remediation emissions profiles. 
Second, all process pollutants emitted by a facility were included as 
the universe of potential pollutants emitted during remediation. While 
site remediation projects likely emit only a subset of the HAP emitted 
by the facility, this assumption was made to ensure no specific 
pollutant was excluded that could represent risk from that facility. 
For several facilities, we found that the emissions profile approach 
had resulted in estimated site remediation emissions that included 
ethylene oxide. These ethylene oxide emissions were removed from the 
source category risk analysis because the EPA considered that ethylene 
oxide would be unlikely to persist in contaminated media long enough to 
be emitted during a site remediation. Additional details on this 
determination can be found in the Residual Risk Assessment for the Site 
Remediation Source Category in Support of the 2019 Risk and Technology 
Proposed Rule, which is available in the docket for this action. The 
EPA requests comment on this model plant approach to address data gaps 
in the RTR, and HAP emissions from the Site Remediation source 
category. (C-1)
b. Sources Exempt From the Site Remediation NESHAP
    The Site Remediation NESHAP currently exempts site remediation 
activities conducted under federal oversight authority under the 
Comprehensive Environmental Response, Compensation, and Liability Act 
(CERCLA) or Resource Conservation and Recovery Act (RCRA) corrective 
action or other required RCRA order (see 40 CFR 63.7881(b)(3)). In 
2016, in response to a petition for

[[Page 46145]]

reconsideration regarding this exemption and other aspects of the 
NESHAP, the EPA proposed to revise the NESHAP to remove the exemption 
for site remediation activities conducted under the authority of CERCLA 
or RCRA (81 FR 29821, May 13, 2016). At proposal, the EPA developed a 
list of 125 facilities that could potentially become subject to the 
rule upon promulgation if the exemption for remediation projects 
subject to RCRA or CERCLA standards was removed.\5\ Although exempt 
from the regulatory requirements of the Site Remediation NESHAP, these 
facilities are part of the Site Remediation source category. To 
understand both the risks from the facilities already subject to the 
Site Remediation NESHAP requirements and the risks from the facilities 
exempt from the Site Remediation NESHAP requirements, these groups of 
facilities were kept separate for the purposes of the risk assessment.
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    \5\ Stobert, L. EC/R Inc. to Hirtz, J., EPA/OAQPS. National 
Impacts Associated with the Proposed Amendments to Remove the 
Exemption for Facilities Performing Site Remediations under CERCLA 
or RCRA in the NESHAP for Site Remediation. February 4, 2016. EPA 
Docket Item No. EPA-HQ-OAR-2002-0021-0055. The EPA estimated in 2016 
that of the 125 facilities listed, only 69 would likely become 
subject to the rule. For the purpose of the risk review, the EPA 
modeled the 118 facilities that could be identified in the NEI.
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    A process similar to that used to estimate emissions from affected 
facilities was used for the exempt facilities. The EPA began with the 
list of 125 facilities previously developed and queried the NEI to 
obtain facility and emissions data for the 2014 reporting-year. 
Information was available in the NEI for 118 of these facilities.\6\ Of 
the 118 facilities with data retrieved from the NEI, 10 facilities 
reported emissions under the SCC for site remediation, and 108 reported 
emissions only from their production activity and did not report any 
emissions for remediation activities. For these 108 facilities, the EPA 
applied the same site remediation emissions ratio as that used for 
affected sources to the whole-facility HAP emissions to arrive at a 
unique site remediation emission profile for each facility. For these 
facilities, we used the same assumptions with respect to ethylene oxide 
emissions as were made in the affected facility modeling.
---------------------------------------------------------------------------

    \6\ Seven of the 125 facilities were unable to be clearly 
identified in the NEI and were not modeled.
---------------------------------------------------------------------------

2. How did we estimate MACT-allowable emissions?
    The available emissions data in the RTR emissions dataset include 
estimates of the mass of HAP emitted during a specified annual time 
period. These ``actual'' emission levels are often lower than the 
emission levels allowed under the requirements of the current MACT 
standards. The emissions allowed under the MACT standards are referred 
to as the ``MACT-allowable'' emissions. We discussed the consideration 
of both MACT-allowable and actual emissions in the final Coke Oven 
Batteries RTR (70 FR 19998-19999, April 15, 2005) and in the proposed 
and final Hazardous Organic NESHAP RTR (71 FR 34428, June 14, 2006, and 
71 FR 76609, December 21, 2006, respectively). In those actions, we 
noted that assessing the risk at the MACT-allowable level is inherently 
reasonable since that risk reflects the maximum level facilities could 
emit and still comply with national emission standards. We also 
explained that it is reasonable to consider actual emissions, where 
such data are available, in both steps of the risk analysis, in 
accordance with the Benzene NESHAP approach. (54 FR 38044, September 
14, 1989.)
    For the Site Remediation source category, the EPA treated actual 
emissions as allowable emissions. Allowable emissions under typical 
MACT standards are the emissions that would occur under full-capacity 
potential operating conditions and as allowed under the applicable MACT 
standards. These are the conditions included in the title V permit for 
the facility. In the case of site remediation, most remediation 
projects do not appear in the title V permit or appear there for 
approximately the duration of the remediation and are then removed. 
Since most facilities performing remediation have the incentive to 
conclude remediation expeditiously, the EPA assumed that actual 
emissions would equal allowed emissions under a facility permit. Where 
no permit condition was available, the EPA assumed the remediation was 
being conducted at full capacity to complete the remediation as soon as 
possible. Based on the NEI data available and the relatively little 
information found in title V permits for remediation projects, the EPA 
modeled actual emissions as allowable emissions.
3. How do we conduct dispersion modeling, determine inhalation 
exposures, and estimate individual and population inhalation risk?
    Both long-term and short-term inhalation exposure concentrations 
and health risk from the source category addressed in this proposal 
were estimated using the Human Exposure Model (HEM-3).\7\ The HEM-3 
performs three primary risk assessment activities: (1) Conducting 
dispersion modeling to estimate the concentrations of HAP in ambient 
air, (2) estimating long-term and short-term inhalation exposures to 
individuals residing within 50 kilometers (km) of the modeled sources, 
and (3) estimating individual and population-level inhalation risk 
using the exposure estimates and quantitative dose-response 
information.
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    \7\ For more information about HEM-3, go to https://www.epa.gov/fera/risk-assessment-and-modeling-human-exposure-model-hem.
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a. Dispersion Modeling
    The air dispersion model AERMOD, used by the HEM-3 model, is one of 
the EPA's preferred models for assessing air pollutant concentrations 
from industrial facilities.\8\ To perform the dispersion modeling and 
to develop the preliminary risk estimates, HEM-3 draws on three data 
libraries. The first is a library of meteorological data, which is used 
for dispersion calculations. This library includes 1 year (2016) of 
hourly surface and upper air observations from 824 meteorological 
stations, selected to provide coverage of the United States and Puerto 
Rico. A second library of United States Census Bureau census block \9\ 
internal point locations and populations provides the basis of human 
exposure calculations (U.S. Census, 2010). In addition, for each census 
block, the census library includes the elevation and controlling hill 
height, which are also used in dispersion calculations. A third library 
of pollutant-specific dose-response values is used to estimate health 
risk. These are discussed below.
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    \8\ U.S. EPA. Revision to the Guideline on Air Quality Models: 
Adoption of a Preferred General Purpose (Flat and Complex Terrain) 
Dispersion Model and Other Revisions (70 FR 68218, November 9, 
2005).
    \9\ A census block is the smallest geographic area for which 
census statistics are tabulated.
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b. Risk From Chronic Exposure to HAP
    In developing the risk assessment for chronic exposures, we use the 
estimated annual average ambient air concentrations of each HAP emitted 
by each source in the source category. The HAP air concentrations at 
each nearby census block centroid located within 50 km of the facility 
are a surrogate for the chronic inhalation exposure concentration for 
all the people who reside in that census block. A distance of 50 km is 
consistent with both the analysis supporting the 1989 Benzene NESHAP 
(54 FR 38044, September 14, 1989) and the limitations of Gaussian 
dispersion models, including AERMOD.

[[Page 46146]]

    For each facility, we calculate the MIR as the cancer risk 
associated with a continuous lifetime (24 hours per day, 7 days per 
week, 52 weeks per year, 70 years) exposure to the maximum 
concentration at the centroid of each inhabited census block. We 
calculate individual cancer risk by multiplying the estimated lifetime 
exposure to the ambient concentration of each HAP (in micrograms per 
cubic meter ([mu]g/m \3\)) by its unit risk estimate (URE). The URE is 
an upper-bound estimate of an individual's incremental risk of 
contracting cancer over a lifetime of exposure to a concentration of 1 
microgram of the pollutant per cubic meter of air. For residual risk 
assessments, we generally use UREs from the EPA's Integrated Risk 
Information System (IRIS). For carcinogenic pollutants without IRIS 
values, we look to other reputable sources of cancer dose-response 
values, often using California EPA (CalEPA) UREs, where available. In 
cases where new, scientifically credible dose-response values have been 
developed in a manner consistent with EPA guidelines and have undergone 
a peer review process similar to that used by the EPA, we may use such 
dose-response values in place of, or in addition to, other values, if 
appropriate. The pollutant-specific dose-response values used to 
estimate health risk are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
    To estimate individual lifetime cancer risks associated with 
exposure to HAP emissions from each facility in the source category, we 
sum the risks for each of the carcinogenic HAP \10\ emitted by the 
modeled facility. We estimate cancer risk at every census block within 
50 km of every facility in the source category. The MIR is the highest 
individual lifetime cancer risk estimated for any of those census 
blocks. In addition to calculating the MIR, we estimate the 
distribution of individual cancer risks for the source category by 
summing the number of individuals within 50 km of the sources whose 
estimated risk falls within a specified risk range. We also estimate 
annual cancer incidence by multiplying the estimated lifetime cancer 
risk at each census block by the number of people residing in that 
block, summing results for all of the census blocks, and then dividing 
this result by a 70-year lifetime.
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    \10\ The EPA's 2005 Guidelines for Carcinogen Risk Assessment 
classifies carcinogens as: ``carcinogenic to humans,'' ``likely to 
be carcinogenic to humans,'' and ``suggestive evidence of 
carcinogenic potential.'' These classifications also coincide with 
the terms ``known carcinogen, probable carcinogen, and possible 
carcinogen,'' respectively, which are the terms advocated in the 
EPA's Guidelines for Carcinogen Risk Assessment, published in 1986 
(51 FR 33992, September 24, 1986). In August 2000, the document, 
Supplemental Guidance for Conducting Health Risk Assessment of 
Chemical Mixtures (EPA/630/R-00/002), was published as a supplement 
to the 1986 document. Copies of both documents can be obtained from 
https://cfpub.epa.gov/ncea/risk/recorddisplay.cfm?deid=20533&CFID=70315376&CFTOKEN=71597944. Summing 
the risk of these individual compounds to obtain the cumulative 
cancer risk is an approach that was recommended by the EPA's SAB in 
their 2002 peer review of the EPA's National Air Toxics Assessment 
(NATA) titled, NATA--Evaluating the National-scale Air Toxics 
Assessment 1996 Data--an SAB Advisory, available at https://
yosemite.epa.gov/sab/sabproduct.nsf/
214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.
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    To assess the risk of noncancer health effects from chronic 
exposure to HAP, we calculate either an HQ or a target organ-specific 
hazard index (TOSHI). We calculate an HQ when a single noncancer HAP is 
emitted. Where more than one noncancer HAP is emitted, we sum the HQ 
for each of the HAP that affects a common target organ or target organ 
system to obtain a TOSHI. The HQ is the estimated exposure divided by 
the chronic noncancer dose-response value, which is a value selected 
from one of several sources. The preferred chronic noncancer dose-
response value is the EPA RfC, defined as ``an estimate (with 
uncertainty spanning perhaps an order of magnitude) of a continuous 
inhalation exposure to the human population (including sensitive 
subgroups) that is likely to be without an appreciable risk of 
deleterious effects during a lifetime'' (https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary). In cases where an RfC 
from the EPA's IRIS is not available or where the EPA determines that 
using a value other than the RfC is appropriate, the chronic noncancer 
dose-response value can be a value from the following prioritized 
sources, which define their dose-response values similarly to the EPA: 
(1) The Agency for Toxic Substances and Disease Registry (ATSDR) 
Minimum Risk Level (https://www.atsdr.cdc.gov/mrls/index.asp); (2) the 
CalEPA Chronic Reference Exposure Level (REL) (https://oehha.ca.gov/air/crnr/notice-adoption-air-toxics-hot-spots-program-guidance-manual-preparation-health-risk-0); or (3), as noted above, a scientifically 
credible dose-response value that has been developed in a manner 
consistent with the EPA guidelines and has undergone a peer review 
process similar to that used by the EPA. The pollutant-specific dose-
response values used to estimate health risks are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
c. Risk From Acute Exposure to HAP That May Cause Health Effects Other 
Than Cancer
    For each HAP for which appropriate acute inhalation dose-response 
values are available, the EPA also assesses the potential health risks 
due to acute exposure. For these assessments, the EPA makes 
conservative assumptions about emission rates, meteorology, and 
exposure location. In this proposed rulemaking, as part of our efforts 
to continually improve our methodologies to evaluate the risks that HAP 
emitted from categories of industrial sources pose to human health and 
the environment,\11\ we are revising our treatment of meteorological 
data to use reasonable worst-case air dispersion conditions in our 
acute risk screening assessments instead of worst-case air dispersion 
conditions. This revised treatment of meteorological data and the 
supporting rationale are described in more detail in Residual Risk 
Assessment for the Site Remediation Source Category in Support of the 
2019 Risk and Technology Review Proposed Rule and in Appendix 5 of the 
report: Technical Support Document for Acute Risk Screening Assessment. 
We will be applying this revision in RTR rulemakings proposed on or 
after June 3, 2019.
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    \11\ U.S. EPA. Screening Methodologies to Support Risk and 
Technology Reviews (RTR): A Case Study Analysis (Draft Report, May 
2017. https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html).
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    To assess the potential acute risk to the maximally exposed 
individual, we use the peak hourly emission rate for each emission 
point,\12\ reasonable worst-case air dispersion conditions (i.e., 99th 
percentile), and the point of highest off-site exposure. Specifically, 
we assume that peak emissions from the source category and reasonable 
worst-case air dispersion conditions co-occur and that a person is 
present at the point of maximum exposure.
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    \12\ In the absence of hourly emission data, we develop 
estimates of maximum hourly emission rates by multiplying the 
average actual annual emissions rates by a factor (either a 
category-specific factor or a default factor of 10) to account for 
variability. This is documented in Residual Risk Assessment for Site 
Remediation Source Category in Support of the 2019 Risk and 
Technology Review Proposed Rule and in Appendix 5 of the report: 
Technical Support Document for Acute Risk Screening Assessment. Both 
are available in the docket for this rulemaking.
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    To characterize the potential health risks associated with 
estimated acute

[[Page 46147]]

inhalation exposures to a HAP, we generally use multiple acute dose-
response values, including acute RELs, acute exposure guideline levels 
(AEGLs), and emergency response planning guidelines (ERPG) for 1-hour 
exposure durations), if available, to calculate acute HQs. The acute HQ 
is calculated by dividing the estimated acute exposure concentration by 
the acute dose-response value. For each HAP for which acute dose-
response values are available, the EPA calculates acute HQs.
    An acute REL is defined as ``the concentration level at or below 
which no adverse health effects are anticipated for a specified 
exposure duration.'' \13\ Acute RELs are based on the most sensitive, 
relevant, adverse health effect reported in the peer-reviewed medical 
and toxicological literature. They are designed to protect the most 
sensitive individuals in the population through the inclusion of 
margins of safety. Because margins of safety are incorporated to 
address data gaps and uncertainties, exceeding the REL does not 
automatically indicate an adverse health impact. AEGLs represent 
threshold exposure limits for the general public and are applicable to 
emergency exposures ranging from 10 minutes to 8 hours.\14\ They are 
guideline levels for ``once-in-a-lifetime, short-term exposures to 
airborne concentrations of acutely toxic, high-priority chemicals.'' 
Id. at 21. The AEGL-1 is specifically defined as ``the airborne 
concentration (expressed as ppm (parts per million) or mg/m\3\ 
(milligrams per cubic meter)) of a substance above which it is 
predicted that the general population, including susceptible 
individuals, could experience notable discomfort, irritation, or 
certain asymptomatic nonsensory effects. However, the effects are not 
disabling and are transient and reversible upon cessation of 
exposure.'' The document also notes that ``Airborne concentrations 
below AEGL-1 represent exposure levels that can produce mild and 
progressively increasing but transient and nondisabling odor, taste, 
and sensory irritation or certain asymptomatic, nonsensory effects.'' 
Id. AEGL-2 are defined as ``the airborne concentration (expressed as 
parts per million or milligrams per cubic meter) of a substance above 
which it is predicted that the general population, including 
susceptible individuals, could experience irreversible or other 
serious, long-lasting adverse health effects or an impaired ability to 
escape.'' Id.
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    \13\ CalEPA issues acute RELs as part of its Air Toxics Hot 
Spots Program, and the 1-hour and 8-hour values are documented in 
Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The 
Determination of Acute Reference Exposure Levels for Airborne 
Toxicants, which is available at https://oehha.ca.gov/air/general-info/oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary.
    \14\ National Academy of Sciences, 2001. Standing Operating 
Procedures for Developing Acute Exposure Levels for Hazardous 
Chemicals, page 2. Available at https://www.epa.gov/sites/production/files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. Note that the 
National Advisory Committee for Acute Exposure Guideline Levels for 
Hazardous Substances ended in October 2011, but the AEGL program 
continues to operate at the EPA and works with the National 
Academies to publish final AEGLs, (https://www.epa.gov/aegl).
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    ERPGs are ``developed for emergency planning and are intended as 
health-based guideline concentrations for single exposures to 
chemicals.'' \15\ Id. at 1. The ERPG-1 is defined as ``the maximum 
airborne concentration below which it is believed that nearly all 
individuals could be exposed for up to 1 hour without experiencing 
other than mild transient adverse health effects or without perceiving 
a clearly defined, objectionable odor.'' Id. at 2. Similarly, the ERPG-
2 is defined as ``the maximum airborne concentration below which it is 
believed that nearly all individuals could be exposed for up to one 
hour without experiencing or developing irreversible or other serious 
health effects or symptoms which could impair an individual's ability 
to take protective action.'' Id. at 1.
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    \15\ American Industrial Hygiene Association. ERPGS Procedures 
and Responsibilities. March 2014. Available at: https://www.aiha.org/get-involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPG%20Committee%20Standard%20Operating%20Procedures%20%20-%20March%202014%20Revision%20%28Updated%2010-2-2014%29.pdf.
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    An acute REL for 1-hour exposure durations is typically lower than 
its corresponding AEGL-1 and ERPG-1. Even though their definitions are 
slightly different, AEGL-1s are often the same as the corresponding 
ERPG-1s, and AEGL-2s are often equal to ERPG-2s. The maximum HQs from 
our acute inhalation screening risk assessment typically result when we 
use the acute REL for a HAP. In cases where the maximum acute HQ 
exceeds 1, we also report the HQ based on the next highest acute dose-
response value (usually the AEGL-1 and/or the ERPG-1).
    For this source category, we used a default acute emissions 
multiplier of 10 as hourly emissions data from site remediation 
activities were generally not available.
    In our acute inhalation screening risk assessment, acute impacts 
are deemed negligible for HAP for which acute HQs are less than or 
equal to 1, and no further analysis is performed for these HAP. In 
cases where an acute HQ from the screening step is greater than 1, we 
assess the site-specific data to ensure the acute HQ is an off-site 
location.
4. How do we conduct the multipathway exposure and risk screening 
assessment?
    The EPA conducts a tiered screening assessment examining the 
potential for significant human health risks due to exposures via 
routes other than inhalation (i.e., ingestion). We first determine 
whether any sources in the source category emit any PB-HAP, as 
identified in the EPA's Air Toxics Risk Assessment Library (see Volume 
1, Appendix D, at https://www.epa.gov/sites/production/files/2013-08/documents/volume_1_reflibrary.pdf).
    For the Site Remediation source category, we identified PB-HAP 
emissions of arsenic compounds, cadmium compounds, mercury compounds, 
polycyclic organic matter (POM), and lead compounds, so we proceeded to 
the next step of the evaluation. In this step, we determine whether the 
facility-specific emission rates of the emitted PB-HAP are large enough 
to create the potential for significant human health risk through 
ingestion exposure under reasonable worst-case conditions. To 
facilitate this step, we use previously developed screening threshold 
emission rates for several PB-HAP that are based on a hypothetical 
upper-end screening exposure scenario developed for use in conjunction 
with the EPA's Total Risk Integrated Methodology.Fate, Transport, and 
Ecological Exposure (TRIM.FaTE) model. The PB-HAP with screening 
threshold emission rates are arsenic compounds, cadmium compounds, 
chlorinated dibenzodioxins and furans, mercury compounds, and POM. 
Based on the EPA estimates of toxicity and bioaccumulation potential, 
the pollutants above represent a conservative list for inclusion in 
multipathway risk assessments for RTR rules. (See Volume 1, Appendix D 
at https://www.epa.gov/sites/production/files/201308/documents/volume_1_reflibrary.pdf.) In this assessment, we compare the facility-
specific emission rates of these PB-HAP to the screening threshold 
emission rates for each PB-HAP to assess the potential for significant 
human health risks via the ingestion pathway (combined ingestion rates 
for a fisher and farmer scenario). We call this application of the 
TRIM.FaTE model the Tier 1 screening assessment. The ratio of a 
facility's actual emission rate to the Tier 1 screening threshold 
emission rate is a ``screening value.''

[[Page 46148]]

    We derive the Tier 1 screening threshold emission rates for these 
PB-HAP (other than lead compounds) to correspond to a maximum excess 
lifetime cancer risk of 1-in-1 million (i.e., for arsenic compounds, 
polychlorinated dibenzodioxins and furans and POM) or, for HAP that 
cause noncancer health effects (i.e., cadmium compounds and mercury 
compounds), a maximum HQ of 1. If the emission rate of any one PB-HAP 
or combination of carcinogenic PB-HAP in the Tier 1 screening 
assessment exceeds the Tier 1 screening threshold emission rate for any 
facility (i.e., the screening value is greater than 1), we conduct a 
second screening assessment, which we call the Tier 2 screening 
assessment (ingestion rates are decoupled into separate upper-bound 
ingestion rates for the fisher, farmer, and gardener scenarios).
    In the Tier 2 screening assessment, the location of each facility 
that exceeds a Tier 1 screening threshold emission rate is used to 
refine the assumptions associated with the Tier 1 fisher and farmer 
exposure scenarios at that facility. A key assumption in the Tier 1 
screening assessment is that a lake and/or farm is located near the 
facility. As part of the Tier 2 screening assessment for the fisher 
scenario, we use a U.S. Geological Survey (USGS) database to identify 
actual waterbodies within 50 km of each facility and assume the fisher 
only consumes fish from lakes within that 50 km zone. For the Tier 2 
farmer scenario, we assume the farmer consumes meat, eggs, vegetables, 
and fruit grown near the facility. If further Tier 2 screening is 
necessary for the farmer scenario, we may also assess the gardener 
scenario. For the gardener scenario, we assume the gardener only grows 
and consumes eggs, vegetables, and fruit at the same ingestion rate as 
the farmer. For Tier 2, we replace the meteorology used in the Tier 1 
screening assessment with the local meteorology near each facility. We 
then adjust the previously-developed Tier 1 screening threshold 
emission rates for each PB-HAP for each facility based on an 
understanding of how exposure concentrations estimated for the 
screening scenario change with the use of local meteorology and USGS 
waterbody data. If the PB-HAP emission rates for a facility exceed the 
Tier 2 screening threshold emission rates and data are available, we 
may conduct a Tier 3 screening assessment, or if the screening values 
are excessively high, go straight to a site-specific assessment 
utilizing TRIM FaTE. If PB-HAP emission rates do not exceed a Tier 2 
screening value of 1, we consider those PB-HAP emissions to pose risks 
below a level of concern.
    There are several analyses that can be included in a Tier 3 
screening assessment, depending upon the extent of refinement 
warranted, including validating that the lakes are fishable, 
considering plume-rise to estimate emissions lost above the mixing 
layer, and considering hourly effects of meteorology and plume rise on 
chemical fate and transport. If the Tier 3 screening assessment 
indicates that risks above levels of concern cannot be ruled out, the 
EPA may further refine the screening assessment through a site-specific 
assessment.
    For further information on the multipathway assessment approach, 
see the Residual Risk Assessment for the Site Remediation Source 
Category in Support of the Risk and Technology Review 2019 Proposed 
Rule, which is available in the docket for this action.
5. How do we assess risks considering emissions control options?
    In addition to assessing baseline inhalation risks and screening 
for potential multipathway risks, we also estimate risks considering 
the potential emission reductions that would be achieved by the control 
options under consideration. In these cases, the expected emission 
reductions are applied to the specific HAP and emission points in the 
RTR emissions dataset to develop corresponding estimates of risk and 
incremental risk reductions.
6. How do we conduct the environmental risk screening assessment?
a. Adverse Environmental Effect, Environmental HAP, and Ecological 
Benchmarks
    The EPA conducts a screening assessment to examine the potential 
for an adverse environmental effect as required under section 
112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA defines ``adverse 
environmental effect'' as ``any significant and widespread adverse 
effect, which may reasonably be anticipated, to wildlife, aquatic life, 
or other natural resources, including adverse impacts on populations of 
endangered or threatened species or significant degradation of 
environmental quality over broad areas.''
    The EPA focuses on eight HAP, which are referred to as 
``environmental HAP,'' in its screening assessment: Six PB-HAP and two 
acid gases. The PB-HAP included in the screening assessment are arsenic 
compounds, cadmium compounds, dioxins/furans, POM, mercury (both 
inorganic mercury and methyl mercury), and lead compounds. The acid 
gases included in the screening assessment are hydrochloric acid (HCl) 
and hydrogen fluoride (HF).
    HAP that persist and bioaccumulate are of particular environmental 
concern because they accumulate in the soil, sediment, and water. The 
acid gases, HCl and HF, are included due to their well-documented 
potential to cause direct damage to terrestrial plants. In the 
environmental risk screening assessment, we evaluate the following four 
exposure media: Terrestrial soils, surface water bodies (includes 
water-column and benthic sediments), fish consumed by wildlife, and 
air. Within these four exposure media, we evaluate nine ecological 
assessment endpoints, which are defined by the ecological entity and 
its attributes. For PB-HAP (other than lead), both community-level and 
population-level endpoints are included. For acid gases, the ecological 
assessment evaluated is terrestrial plant communities.
    An ecological benchmark represents a concentration of HAP that has 
been linked to a particular environmental effect level. For each 
environmental HAP, we identified the available ecological benchmarks 
for each assessment endpoint. We identified, where possible, ecological 
benchmarks at the following effect levels: Probable effect levels, 
lowest-observed-adverse-effect level, and no-observed-adverse-effect 
level. In cases where multiple effect levels were available for a 
particular PB-HAP and assessment endpoint, we use all of the available 
effect levels to help us to determine whether ecological risks exist 
and, if so, whether the risks could be considered significant and 
widespread.
    For further information on how the environmental risk screening 
assessment was conducted, including a discussion of the risk metrics 
used, how the environmental HAP were identified, and how the ecological 
benchmarks were selected, see Appendix 9 of the Residual Risk 
Assessment for the Site Remediation Source Category in Support of the 
Risk and Technology Review 2019 Proposed Rule, which is available in 
the docket for this action.
b. Environmental Risk Screening Methodology
    For the environmental risk screening assessment, the EPA first 
determined whether any facilities in the Site Remediation source 
category emitted any of the environmental HAP. For the Site Remediation 
source category, we identified emissions of arsenic

[[Page 46149]]

compounds, cadmium compounds, mercury compounds, POM, HCl, and 
hydrofluoric acid. Because one or more of the environmental HAP 
evaluated (arsenic compounds, cadmium compounds, mercury compounds, 
POM, lead compounds, and HCl, and hydrofluoric acid) are emitted by at 
least one facility in the source category, we proceeded to the second 
step of the evaluation.\16\
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    \16\ The environmental HAP emitted by facilities modeled were 
not attributed to Site Remediation source category emissions, but 
rather were emitted from other emission points at the facility. 
These pollutants were profiled as part of model plant emissions 
because the facility otherwise emits environmental HAP.
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c. PB-HAP Methodology
    The environmental screening assessment includes six PB-HAP, arsenic 
compounds, cadmium compounds, dioxins/furans, POM, mercury (both 
inorganic mercury and methyl mercury), and lead compounds. With the 
exception of lead, the environmental risk screening assessment for PB-
HAP consists of three tiers. The first tier of the environmental risk 
screening assessment uses the same health-protective conceptual model 
that is used for the Tier 1 human health screening assessment. 
TRIM.FaTE model simulations were used to back-calculate Tier 1 
screening threshold emission rates. The screening threshold emission 
rates represent the emission rate in tons of pollutant per year that 
results in media concentrations at the facility that equal the relevant 
ecological benchmark. To assess emissions from each facility in the 
category, the reported emission rate for each PB-HAP was compared to 
the Tier 1 screening threshold emission rate for that PB-HAP for each 
assessment endpoint and effect level. If emissions from a facility do 
not exceed the Tier 1 screening threshold emission rate, the facility 
``passes'' the screening assessment, and, therefore, is not evaluated 
further under the screening approach. If emissions from a facility 
exceed the Tier 1 screening threshold emission rate, we evaluate the 
facility further in Tier 2.
    In Tier 2 of the environmental screening assessment, the screening 
threshold emission rates are adjusted to account for local meteorology 
and the actual location of lakes in the vicinity of facilities that did 
not pass the Tier 1 screening assessment. For soils, we evaluate the 
average soil concentration for all soil parcels within a 7.5-km radius 
for each facility and PB-HAP. For the water, sediment, and fish tissue 
concentrations, the highest value for each facility for each pollutant 
is used. If emission concentrations from a facility do not exceed the 
Tier 2 screening threshold emission rate, the facility ``passes'' the 
screening assessment and typically is not evaluated further. If 
emissions from a facility exceed the Tier 2 screening threshold 
emission rate, we evaluate the facility further in Tier 3.
    As in the multipathway human health risk assessment, in Tier 3 of 
the environmental screening assessment, we examine the suitability of 
the lakes around the facilities to support life and remove those that 
are not suitable (e.g., lakes that have been filled in or are 
industrial ponds), adjust emissions for plume-rise, and conduct hour-
by-hour time-series assessments. If these Tier 3 adjustments to the 
screening threshold emission rates still indicate the potential for an 
adverse environmental effect (i.e., facility emission rate exceeds the 
screening threshold emission rate), we may elect to conduct a more 
refined assessment using more site-specific information. If, after 
additional refinement, the facility emission rate still exceeds the 
screening threshold emission rate, the facility may have the potential 
to cause an adverse environmental effect.
    To evaluate the potential for an adverse environmental effect from 
lead, we compared the average modeled air concentrations (from HEM-3) 
of lead around each facility in the source category to the level of the 
secondary National Ambient Air Quality Standards (NAAQS) for lead. The 
secondary lead NAAQS is a reasonable means of evaluating environmental 
risk because it is set to provide substantial protection against 
adverse welfare effects which can include ``effects on soils, water, 
crops, vegetation, man-made materials, animals, wildlife, weather, 
visibility and climate, damage to and deterioration of property, and 
hazards to transportation, as well as effects on economic values and on 
personal comfort and well-being.''
d. Acid Gas Environmental Risk Methodology
    The environmental screening assessment for acid gases evaluates the 
potential phytotoxicity and reduced productivity of plants due to 
chronic exposure to HF and HCl. The environmental risk screening 
methodology for acid gases is a single-tier screening assessment that 
compares modeled ambient air concentrations (from AERMOD) to the 
ecological benchmarks for each acid gas. To identify a potential 
adverse environmental effect (as defined in section 112(a)(7) of the 
CAA) from emissions of HF and HCl, we evaluate the following metrics: 
the size of the modeled area around each facility that exceeds the 
ecological benchmark for each acid gas, in acres and km\2\; the 
percentage of the modeled area around each facility that exceeds the 
ecological benchmark for each acid gas; and the area-weighted average 
screening value around each facility (Calculated by dividing the area-
weighted average concentration over the 50-km modeling domain by the 
ecological benchmark for each acid gas). For further information on the 
environmental screening assessment approach, see Appendix 9 of the 
Residual Risk Assessment for the Site Remediation Source Category in 
Support of the Risk and Technology Review 2019 Proposed Rule, which is 
available in the docket for this action.
7. How do we conduct facility-wide assessments?
    To put the source category risks in context, we typically examine 
the risks from the entire ``facility,'' where the facility includes all 
HAP-emitting operations within a contiguous area and under common 
control. In other words, we examine the HAP emissions not only from the 
source category emission points of interest, but also emissions of HAP 
from all other emission sources at the facility for which we have data.
    For this source category, we conducted the facility-wide assessment 
using a dataset that the EPA compiled from the 2014 NEI. We used the 
NEI data for the facility and did not adjust any category or ``non-
category'' data. Therefore, there could be differences in the dataset 
from that used for the source category assessments described in this 
preamble. We analyzed risks due to the inhalation of HAP that are 
emitted ``facility-wide'' for the populations residing within 50 km of 
each facility, consistent with the methods used for the source category 
analysis described above. For these facility-wide risk analyses, we 
made a reasonable attempt to identify the source category risks, and 
these risks were compared to the facility-wide risks to determine the 
portion of facility-wide risks that could be attributed to the source 
category addressed in this proposal. We also specifically examined the 
facility that was associated with the highest estimate of risk and 
determined the percentage of that risk attributable to the source 
category of interest. The Residual Risk Assessment for the Site 
Remediation Source Category in Support of the Risk and Technology 
Review 2019 Proposed Rule, available through the docket for this 
action, provides the methodology and results of the facility-wide 
analyses,

[[Page 46150]]

including all facility-wide risks and the percentage of source category 
contribution to facility-wide risks.
8. How do we consider uncertainties in risk assessment?
    Uncertainty and the potential for bias are inherent in all risk 
assessments, including those performed for this proposal. Although 
uncertainty exists, we believe that our approach, which used 
conservative tools and assumptions, ensures that our decisions are 
health and environmentally protective. A brief discussion of the 
uncertainties in the RTR emissions dataset, dispersion modeling, 
inhalation exposure estimates, and dose-response relationships follows 
below. Also included are those uncertainties specific to our acute 
screening assessments, multipathway screening assessments, and our 
environmental risk screening assessments. A more thorough discussion of 
these uncertainties is included in the Residual Risk Assessment for the 
Site Remediation Source Category in Support of the Risk and Technology 
Review 2019 Proposed Rule, which is available in the docket for this 
action. If a multipathway site-specific assessment was performed for 
this source category, a full discussion of the uncertainties associated 
with that assessment can be found in Appendix 11 of that document, 
Site-Specific Human Health Multipathway Residual Risk Assessment 
Report.
a. Uncertainties in the RTR Emissions Dataset
    Although the development of the RTR emissions dataset involved 
quality assurance/quality control processes, the accuracy of emissions 
values will vary depending on the source of the data, the degree to 
which data are incomplete or missing, the degree to which assumptions 
made to complete the datasets are accurate, errors in emission 
estimates, and other factors. The emission estimates considered in this 
analysis generally are annual totals for certain years, and they do not 
reflect short-term fluctuations during the course of a year or 
variations from year to year. The estimates of peak hourly emission 
rates for the acute effects screening assessment were based on an 
emission adjustment factor applied to the average annual hourly 
emission rates, which are intended to account for emission fluctuations 
due to normal facility operations.
b. Uncertainties in Dispersion Modeling
    We recognize there is uncertainty in ambient concentration 
estimates associated with any model, including the EPA's recommended 
regulatory dispersion model, AERMOD. In using a model to estimate 
ambient pollutant concentrations, the user chooses certain options to 
apply. For RTR assessments, we select some model options that have the 
potential to overestimate ambient air concentrations (e.g., not 
including plume depletion or pollutant transformation). We select other 
model options that have the potential to underestimate ambient impacts 
(e.g., not including building downwash). Other options that we select 
have the potential to either under- or overestimate ambient levels 
(e.g., meteorology and receptor locations). On balance, considering the 
directional nature of the uncertainties commonly present in ambient 
concentrations estimated by dispersion models, the approach we apply in 
the RTR assessments should yield unbiased estimates of ambient HAP 
concentrations. We also note that the selection of meteorology dataset 
location could have an impact on the risk estimates. As we continue to 
update and expand our library of meteorological station data used in 
our risk assessments, we expect to reduce this variability.
c. Uncertainties in Inhalation Exposure Assessment
    Although every effort is made to identify all of the relevant 
facilities and emission points, as well as to develop accurate 
estimates of the annual emission rates for all relevant HAP, the 
uncertainties in our emission inventory likely dominate the 
uncertainties in the exposure assessment. Some uncertainties in our 
exposure assessment include human mobility, using the centroid of each 
census block, assuming lifetime exposure, and assuming only outdoor 
exposures. For most of these factors, there is neither an under nor 
overestimate when looking at the maximum individual risk or the 
incidence, but the shape of the distribution of risks may be affected. 
With respect to outdoor exposures, actual exposures may not be as high 
if people spend time indoors, especially for very reactive pollutants 
or larger particles. For all factors, we reduce uncertainty when 
possible. For example, with respect to census-block centroids, we 
analyze large blocks using aerial imagery and adjust locations of the 
block centroids to better represent the population in the blocks. We 
also add additional receptor locations where the population of a block 
is not well represented by a single location.
d. Uncertainties in Dose-Response Relationships
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from 
chronic exposures and noncancer effects from both chronic and acute 
exposures. Some uncertainties are generally expressed quantitatively, 
and others are generally expressed in qualitative terms. We note, as a 
preface to this discussion, a point on dose-response uncertainty that 
is stated in the EPA's 2005 Guidelines for Carcinogen Risk Assessment; 
namely, that ``the primary goal of EPA actions is protection of human 
health; accordingly, as an Agency policy, risk assessment procedures, 
including default options that are used in the absence of scientific 
data to the contrary, should be health protective'' (the EPA's 2005 
Guidelines for Carcinogen Risk Assessment, page 1-7). This is the 
approach followed here as summarized in the next paragraphs.
    Cancer UREs used in our risk assessments are those that have been 
developed to generally provide an upper bound estimate of risk.\17\ 
That is, they represent a ``plausible upper limit to the true value of 
a quantity'' (although this is usually not a true statistical 
confidence limit). In some circumstances, the true risk could be as low 
as zero; however, in other circumstances the risk could be greater.\18\ 
Chronic noncancer RfC and reference dose (RfD) values represent chronic 
exposure levels that are intended to be health-protective levels. To 
derive dose-response values that are intended to be ``without 
appreciable risk,'' the methodology relies upon an uncertainty factor 
(UF) approach,\19\ which considers uncertainty, variability, and gaps 
in the available data. The UFs are applied to derive dose-response 
values that are intended to protect against appreciable risk of 
deleterious effects.
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    \17\ IRIS glossary (https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary).
    \18\ An exception to this is the URE for benzene, which is 
considered to cover a range of values, each end of which is 
considered to be equally plausible, and which is based on maximum 
likelihood estimates.
    \19\ See A Review of the Reference Dose and Reference 
Concentration Processes, U.S. EPA, December 2002, and Methods for 
Derivation of Inhalation Reference Concentrations and Application of 
Inhalation Dosimetry, U.S. EPA, 1994.
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    Many of the UFs used to account for variability and uncertainty in 
the development of acute dose-response values are quite similar to 
those

[[Page 46151]]

developed for chronic durations. Additional adjustments are often 
applied to account for uncertainty in extrapolation from observations 
at one exposure duration (e.g., 4 hours) to derive an acute dose-
response value at another exposure duration (e.g., 1 hour). Not all 
acute dose-response values are developed for the same purpose, and care 
must be taken when interpreting the results of an acute assessment of 
human health effects relative to the dose-response value or values 
being exceeded. Where relevant to the estimated exposures, the lack of 
acute dose-response values at different levels of severity should be 
factored into the risk characterization as potential uncertainties.
    Uncertainty also exists in the selection of ecological benchmarks 
for the environmental risk screening assessment. We established a 
hierarchy of preferred benchmark sources to allow selection of 
benchmarks for each environmental HAP at each ecological assessment 
endpoint. We searched for benchmarks for three effect levels (i.e., no-
effects level, threshold-effect level, and probable effect level), but 
not all combinations of ecological assessment/environmental HAP had 
benchmarks for all three effect levels. Where multiple effect levels 
were available for a particular HAP and assessment endpoint, we used 
all of the available effect levels to help us determine whether risk 
exists and whether the risk could be considered significant and 
widespread.
    Although we make every effort to identify appropriate human health 
effect dose-response values for all pollutants emitted by the sources 
in this risk assessment, some HAP emitted by this source category are 
lacking dose-response assessments. Accordingly, these pollutants cannot 
be included in the quantitative risk assessment, which could result in 
quantitative estimates understating HAP risk. To help to alleviate this 
potential underestimate, where we conclude similarity with a HAP for 
which a dose-response value is available, we use that value as a 
surrogate for the assessment of the HAP for which no value is 
available. To the extent use of surrogates indicates appreciable risk, 
we may identify a need to increase priority for an IRIS assessment for 
that substance. We additionally note that, generally speaking, HAP of 
greatest concern due to environmental exposures and hazard are those 
for which dose-response assessments have been performed, reducing the 
likelihood of understating risk. Further, HAP not included in the 
quantitative assessment are assessed qualitatively and considered in 
the risk characterization that informs the risk management decisions, 
including consideration of HAP reductions achieved by various control 
options.
    For a group of compounds that are unspeciated (e.g., glycol 
ethers), we conservatively use the most protective dose-response value 
of an individual compound in that group to estimate risk. Similarly, 
for an individual compound in a group (e.g., ethylene glycol diethyl 
ether) that does not have a specified dose-response value, we also 
apply the most protective dose-response value from the other compounds 
in the group to estimate risk.
e. Uncertainties in Acute Inhalation Screening Assessments
    In addition to the uncertainties highlighted above, there are 
several factors specific to the acute exposure assessment that the EPA 
conducts as part of the risk review under section 112 of the CAA. The 
accuracy of an acute inhalation exposure assessment depends on the 
simultaneous occurrence of independent factors that may vary greatly, 
such as hourly emissions rates, meteorology, and the presence of a 
person. In the acute screening assessment that we conduct under the RTR 
program, we assume that peak emissions from the source category and 
reasonable worst-case air dispersion conditions (i.e., 99th percentile) 
co-occur. We then include the additional assumption that a person is 
located at this point at the same time. For this source category, 
together, these assumptions represent a reasonable worst-case exposure 
scenario. In most cases, it is unlikely that a person would be located 
at the point of maximum exposure during the time when peak emissions 
and reasonable worst-case air dispersion conditions occur 
simultaneously.
f. Uncertainties in the Multipathway and Environmental Risk Screening 
Assessments
    For each source category, we generally rely on site-specific levels 
of PB-HAP or environmental HAP emissions to determine whether a refined 
assessment of the impacts from multipathway exposures is necessary or 
whether it is necessary to perform an environmental screening 
assessment. This determination is based on the results of a three-
tiered screening assessment that relies on the outputs from models--
TRIM.FaTE and AERMOD--that estimate environmental pollutant 
concentrations and human exposures for five PB-HAP (dioxins, POM, 
mercury, cadmium, and arsenic) and two acid gases (HF and hydrogen 
chloride). For lead, we use AERMOD to determine ambient air 
concentrations, which are then compared to the secondary NAAQS standard 
for lead. Two important types of uncertainty associated with the use of 
these models in RTR risk assessments and inherent to any assessment 
that relies on environmental modeling are model uncertainty and input 
uncertainty.\20\
---------------------------------------------------------------------------

    \20\ In the context of this discussion, the term ``uncertainty'' 
as it pertains to exposure and risk encompasses both variability in 
the range of expected inputs and screening results due to existing 
spatial, temporal, and other factors, as well as uncertainty in 
being able to accurately estimate the true result.
---------------------------------------------------------------------------

    Model uncertainty concerns whether the model adequately represents 
the actual processes (e.g., movement and accumulation) that might occur 
in the environment. For example, does the model adequately describe the 
movement of a pollutant through the soil? This type of uncertainty is 
difficult to quantify. However, based on feedback received from 
previous EPA SAB reviews and other reviews, we are confident that the 
models used in the screening assessments are appropriate and state-of-
the-art for the multipathway and environmental screening risk 
assessments conducted in support of RTR.
    Input uncertainty is concerned with how accurately the models have 
been configured and parameterized for the assessment at hand. For Tier 
1 of the multipathway and environmental screening assessments, we 
configured the models to avoid underestimating exposure and risk. This 
was accomplished by selecting upper-end values from nationally 
representative datasets for the more influential parameters in the 
environmental model, including selection and spatial configuration of 
the area of interest, lake location and size, meteorology, surface 
water, soil characteristics, and structure of the aquatic food web. We 
also assume an ingestion exposure scenario and values for human 
exposure factors that represent reasonable maximum exposures.
    In Tier 2 of the multipathway and environmental screening 
assessments, we refine the model inputs to account for meteorological 
patterns in the vicinity of the facility versus using upper-end 
national values, and we identify the actual location of lakes near the 
facility rather than the default lake location that we apply in Tier 1. 
By refining the screening approach in Tier 2 to account for local 
geographical and meteorological data, we decrease the likelihood that 
concentrations in

[[Page 46152]]

environmental media are overestimated, thereby increasing the 
usefulness of the screening assessment. In Tier 3 of the screening 
assessments, we refine the model inputs again to account for hour-by-
hour plume rise and the height of the mixing layer. We can also use 
those hour-by-hour meteorological data in a TRIM.FaTE run using the 
screening configuration corresponding to the lake location. These 
refinements produce a more accurate estimate of chemical concentrations 
in the media of interest, thereby reducing the uncertainty with those 
estimates. The assumptions and the associated uncertainties regarding 
the selected ingestion exposure scenario are the same for all three 
tiers.
    For the environmental screening assessment for acid gases, we 
employ a single-tiered approach. We use the modeled air concentrations 
and compare those with ecological benchmarks.
    For all tiers of the multipathway and environmental screening 
assessments, our approach to addressing model input uncertainty is 
generally cautious. We choose model inputs from the upper end of the 
range of possible values for the influential parameters used in the 
models, and we assume that the exposed individual exhibits ingestion 
behavior that would lead to a high total exposure. This approach 
reduces the likelihood of not identifying high risks for adverse 
impacts.
    Despite the uncertainties, when individual pollutants or facilities 
do not exceed screening threshold emission rates (i.e., screen out), we 
are confident that the potential for adverse multipathway impacts on 
human health is very low. On the other hand, when individual pollutants 
or facilities do exceed screening threshold emission rates, it does not 
mean that impacts are significant, only that we cannot rule out that 
possibility and that a refined assessment for the site might be 
necessary to obtain a more accurate risk characterization for the 
source category.
    The EPA evaluates the following HAP in the multipathway and/or 
environmental risk screening assessments, where applicable: Arsenic, 
cadmium, dioxins/furans, lead, mercury (both inorganic and methyl 
mercury), POM, HCl, and HF. These HAP represent pollutants that can 
cause adverse impacts either through direct exposure to HAP in the air 
or through exposure to HAP that are deposited from the air onto soils 
and surface waters and then through the environment into the food web. 
These HAP represent those HAP for which we can conduct a meaningful 
multipathway or environmental screening risk assessment. For other HAP 
not included in our screening assessments, the model has not been 
parameterized such that it can be used for that purpose. In some cases, 
depending on the HAP, we may not have appropriate multipathway models 
that allow us to predict the concentration of that pollutant. The EPA 
acknowledges that other HAP beyond these that we are evaluating may 
have the potential to cause adverse effects and, therefore, the EPA may 
evaluate other relevant HAP in the future, as modeling science and 
resources allow.

IV. Analytical Results and Proposed Decisions

A. What actions are we taking pursuant to CAA sections 112(d)(2) and 
112(d)(3)?

    To ensure that CAA section 112 standards apply at all times, the 
EPA is proposing to add provisions for pressure relief device (PRD) 
releases and for bypass lines on closed vent systems. The results and 
proposed decisions based on the analyses performed pursuant to CAA 
section 112(d)(2) and (3) are presented below.
    The acronym ``PRD'' means pressure relief device and is common 
vernacular to describe the variety of devices regulated as PRDs or 
valves (see the end of this section for our proposed addition of the 
definition for ``pressure relief device'' or ``valve,'' to provide 
clarity). PRDs are designed to remain closed during normal operation, 
but they may ``actuate'' (e.g., the valve seat opens or a rupture disk 
ruptures) in the event of an overpressure in the system caused by 
operator error, a malfunction such as a power failure or equipment 
failure, or other unexpected cause that results in immediate venting of 
gas from process equipment in order to avoid safety hazards or 
equipment damage. For the Site Remediation source category, emissions 
vented directly to the atmosphere from a PRD actuation in remediation 
material service may contain HAP that would have been subject to 
control under the Site Remediation NESHAP, if the PRD actuation had not 
occurred (e.g., through a process vent standard). However, the EPA 
recognizes that the characteristics of a release from a PRD may be 
different from HAP emission generated from remediation processes under 
typical operating conditions (i.e., non malfunction) and which are 
routed through a process vent.
    The Site Remediation NESHAP currently regulates fugitive emissions 
from PRDs, when they are seated, through the equipment leak provisions. 
The equipment leak provisions also require that the PRD be returned to 
a condition of no detectable emissions, after a pressure release; 
however, these equipment leak provisions do not establish a standard 
for emissions releases from a PRD when the PRD actuates. In addition, 
the current Site Remediation NESHAP follows the EPA's previous practice 
of exempting SSM events from otherwise applicable emission standards. 
Consequently, with emissions releases from a PRD release actuation 
event treated as a type of malfunction, the Site Remediation NESHAP did 
not restrict emissions releases from a PRD actuation event to the 
atmosphere (i.e., they were exempt from the otherwise applicable 
emission standards). In Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 
2008), the Court determined SSM exemptions in section 112 standards 
violate the CAA. Section IV.E.2 of this preamble contains additional 
discussions on the removal of the SSM exemptions for this source 
category.
    We evaluated the Site Remediation NESHAP provisions for PRDs to 
ensure a standard continuously applies during malfunctions that result 
in an emissions release from a PRD actuation event, consistent with the 
Sierra Club v. EPA decision. First, we determined that emissions 
releases from PRD actuation events that vent to a closed vent system 
and control device are appropriately regulated. We are proposing at 40 
CFR 63.7923 that emissions releases from a PRD actuation event routed 
through a closed vent system to a control device or to a process, fuel 
gas system, or drain system must meet the requirements at 40 CFR 
63.7925 to 40 CFR 63.7928 for the applicable control system.
    Second, the EPA determined that emissions from PRD actuation events 
that vent directly to the atmosphere as the result of a malfunction may 
not meet an applicable emission standard for this source category. 
Therefore, we examined whether it would be feasible to establish a 
numeric emission standard for emissions releases from PRD actuation 
events that vent directly to the atmosphere.
    As detailed here, we determined it is not feasible to regulate 
emissions from PRD actuation events through a numeric emission 
standard, and, therefore, it is more appropriate to regulate emissions 
releases from PRD events that vent to the atmosphere through work 
practice standards under CAA section 112(h), established consistent 
with CAA section 112(d)(2) and (3). The EPA is proposing work practice 
standards at 40 CFR 63.7923 that are intended to reduce the number of 
emissions releases from PRD actuation events and will incentivize

[[Page 46153]]

owners or operators to eliminate the causes of emissions releases from 
PRD actuation events that vent directly to the atmosphere.
    When the EPA initially promulgated the Site Remediation NESHAP, it 
did not consider malfunction events when establishing emissions 
standards for the various emissions sources at site remediation 
facilities. In undertaking that consideration now, we propose that it 
is not feasible to regulate emissions releases from PRD actuation 
events that vent to the atmosphere using numeric emission limits due to 
technological and economic limitations that make it impracticable to 
measure emissions from PRDs which have actuated. CAA section 112(h)(1) 
states that the EPA may prescribe a work practice standard or other 
requirement, consistent with the provisions of CAA sections 112(d) or 
(f), in those cases where, in the judgment of the Administrator, it is 
not feasible to enforce an emission standard. CAA section 112(h)(2)(B) 
further defines the term ``not feasible'' in this context as meaning 
that ``the application of measurement technology to a particular class 
of sources is not practicable due to technological and economic 
limitations.'' We consider it appropriate to establish a work practice 
standard for emissions releases from PRD actuation events that vent to 
the atmosphere as provided in CAA section 112(h), because the 
application of a measurement methodology for emissions releases from 
PRD actuation events that vent directly to the atmosphere is not 
practicable due to technological and economic limitations. As discussed 
previously, PRDs are designed to remain closed during normal operations 
and release emissions only during nonroutine and unplanned events, and 
the venting time can be very short and may vary widely in emissions 
composition and flow rate.
    Additionally, it would be economically prohibitive to construct an 
appropriate conveyance and install and operate continuous monitoring 
systems for each individual PRD that vents directly to the atmosphere 
in order to attempt to quantitatively measure an actuation release 
event that may occur infrequently. See U.S. v. Sugar Corp., 830 F.3d 
579, 664-67 (D.C. Cir. 2016). Further, we have not identified any 
available, technically feasible continuous emission monitoring system 
that can accurately determine a mass release quantity of HAP given the 
flow, composition, and compositional variability of potential PRD 
releases that vent directly to the atmosphere from remediation units. 
Rather, we have identified only monitoring systems capable of alerting 
an owner or operator when an emissions release from a PRD actuation 
event occurs. Consequently, we propose that it is appropriate to 
establish a work practice standard for emissions releases from PRD 
actuation event that vent directly to the atmosphere as provided in CAA 
section 112(h).
    We next reviewed information about site remediation facilities to 
determine how the best performers are minimizing emissions releases 
from PRD actuation events that vent directly to the atmosphere. A 
review of the title V operating permits for facilities subject to the 
Site Remediation NESHAP indicated that many facilities are subject to 
the Chemical Accident Prevention Provisions (CAP) rule (40 CFR 68.215 
requires permits to list 40 CFR part 68 as an applicable requirement, 
if subject) for at least some portion of the facility. As a result, we 
further reviewed this rule for consideration in developing a PRD work 
practice standard.
    The CAP rule requires facilities to develop a Risk Management Plan 
that includes a hazard assessment, an accident prevention program and 
an emergency response program. The CAP rule includes three program 
levels which dictate the requirements for the hazard assessment, 
accident prevention program and emergency response program based on the 
types of chemicals and processes used at a facility. If the 
applicability of the CAP rule extends to site remediation affected 
facilities, the facilities would fall under either prevention program 
level 1 or 3 (depending on a facility's NAICS code). We evaluated 
program 3, which is more stringent, because based on a review of the 
rule's applicability requirements and preamble rationale, it is our 
understanding that site remediation facilities may not be subject to 
the program 1 criteria. We also chose to evaluate program 3 because if 
any facility is subject to program 3 and the Site Remediation NESHAP, 
those sources would be the best performers in the source category, 
requisite for a MACT determination. The program 3 prevention program 
includes: Documentation of process safety information, conducting a 
hazard analysis, documentation of operating procedures, employee 
training, on-going maintenance, and incident investigations. The 
process safety information documented must include information 
pertaining to the hazards of the regulated substances in the process, 
the technology of the process, and the process equipment (including 
relief valves). When conducting the hazard analysis, facilities must 
identify, evaluate, and control the hazards in the process. Facilities 
that use controls may consider the application of detection 
methodologies (e.g., process monitoring and control instrumentation) to 
provide early warning of releases. The operating procedures must 
address multiple operating scenarios (e.g., normal operations, startup, 
emergency shutdown) and provide instructions for safely conducting 
process activities. The acts of conducting the hazard analysis and 
documenting operating procedures are similar to prevention measures, 
discussed below, though we note a specific number of measures or 
controls is not specified for the program 3 prevention program. 
Incident investigations must document the factors that contributed to 
an incident and any resolutions and corrective actions (incident 
investigations are consistent with analysis of the cause of the release 
and corrective measures, discussed below). Facilities are also required 
to document this information in a Risk Management Plan that must be 
updated at least every 5 years.
    Next, we considered that some companies operating site remediation 
facilities also own and operate petroleum refineries or chemical 
production facilities and may have established company-wide best 
practices as a result of specific state and Federal requirements. For 
example, petroleum refineries located in certain counties in California 
are subject to and complying with specific requirements for PRDs such 
as the Bay Area Air Quality Management District (BAAQMD) Rule 8-28-304 
and South Coast Air Quality Management District (SCAQMD) Rule 1173. 
These rules also formed the basis of the work practice standards 
promulgated for emissions releases from PRD actuation events at 
petroleum refineries in the recent Petroleum Refinery Sector RTR 
performed by the EPA (80 FR 75178, December 1, 2015).
    Considering our review of the EPA's Chemical Accident Prevention 
Provisions and company-wide best practices that site remediation 
facilities may have implemented, we expect that the best performing 
site remediation facilities have implemented a program for emissions 
releases from PRD actuation events that vent directly to the atmosphere 
that consists of conducting an analysis of the cause of the PRD 
actuation event and the implementation of corrective measures. We used 
this information as the basis of the work practice standards that we 
are proposing at 40 CFR 63.7923.
    Specifically, we are proposing a limit on the number of emissions 
releases

[[Page 46154]]

from PRD actuation events that if exceeded, would result in a violation 
to the work practice standard for emissions releases for PRD actuation 
events that vent directly to the atmosphere. We believe setting 
criteria to determine a deviation is necessary for the work practice to 
be effective. We considered limits on the number of emissions releases 
from PRD actuation events over a 3-year period. Based on a Monte Carlo 
analysis of random rare events (conducted for the Petroleum Refinery 
Sector MACT), we note that a facility is likely to have two or three 
events in an average 5-year period when a long time-horizon (e.g., 20 
years) is considered. Therefore, we are proposing to limit the number 
of emissions releases from a PRD actuation event from a single PRD to 
either two or three (depending on the PRD release actuation event 
cause) in a 3-year period as the basis of a deviation of the work 
practice standard. We considered it reasonable to use a 3-year period 
rather than a 5-year period given that company-wide best practices 
forming the basis of the work practice standards promulgated for 
emissions releases from PRD actuation events at petroleum refineries 
are also our underlying basis for the proposed work practice standards 
at site remediation facilities. We are proposing that it is a deviation 
of the work practice standard if a single PRD that vents emissions from 
an actuation event directly to the atmosphere has two releases within a 
3-year period due to the same cause. We believe this provision will 
help ensure that analyses and corrective actions are conducted 
effectively. Otherwise, we are proposing that it is a deviation of the 
work practice standard if a single PRD that vents emissions from an 
actuation event directly to the atmosphere has three releases within a 
3-year period for any reason. In addition, we are proposing that any 
emissions release directly to the atmosphere from a PRD actuation event 
for which the cause was determined to be operator error or poor 
maintenance is a violation of the work practice standard. We are 
proposing that ``force majeure'' events would not be included when 
counting the number of releases. We are proposing to define ``Force 
majeure'' as including events resulting from natural disasters, acts of 
war or terrorism, or external power curtailment beyond the facility's 
control. These types of events are beyond the control of the owner or 
operator. We are providing that these events should not be included in 
the event count, but that they would be subject to the PRD actuation 
event cause analysis in order to confirm or determine whether the 
release was due to a force majeure event.
    In addition, consistent with our treatment of site remediation 
process vents (in general, an open PRD is essentially the same as a 
site remediation process vent that is vented directly to the 
atmosphere), we believe it is appropriate to exclude certain types of 
PRDs that have very low potential to emit based on their type of 
service, size, and/or pressure from the proposed work practice standard 
for PRD releases that vent directly to the atmosphere. Both the CAP and 
the California petroleum refinery PRD rules also exempt or impose 
simpler requirements for certain PRDs. We are proposing at 40 CFR 
63.7923 that the following types of PRDs would not be subject to the 
work practice standard for PRDs that vent directly to the atmosphere: 
(1) PRDs in heavy liquid service; (2) PRDs that are designed solely to 
release due to liquid thermal expansion; and (3) pilot-operated and 
balanced bellows PRDs if the primary release valve associated with the 
PRD is vented through a control system. With regard to PRDs in heavy 
liquid service and thermal relief valves, any release of HAP to the 
atmosphere from a PRD in heavy liquid service would be expected to be 
small. We are also proposing that pilot-operated PRDs (where emissions 
from actuation events can be released to the atmosphere through a pilot 
discharge vent) and balanced bellow PRDs (where emissions can be 
released to the atmosphere through a bonnet vent) are not subject to 
the work practice standard, if the primary release valve associated 
with the PRD is vented through a control system. Due to its design, 
which includes a bellows to shield the pressure relief stem and top 
portion of the valve seat from the discharge vent pressure, a balanced 
bellows PRD will not discharge gas to the atmosphere during a pressure 
release actuation event, except for potential leaks through the bonnet 
vent due to bellows failure or fatigue which are not considered PRD 
actuation. Pilot-operated PRDs use a small pilot safety valve that 
discharges to the atmosphere to actuate the primary valve or piston, 
which then discharges to a control system. The EPA considers balanced 
bellows and pilot operated PRDs to be equipment that safely controls 
the primary PRD release and reduces HAP emissions to the atmosphere.
    The PRDs subject to the Site Remediation NESHAP that vent to a 
control device are exempt from LDAR. The PRDs that vent to the 
atmosphere are subject to the LDAR provisions of either 40 CFR part 63, 
subpart TT or UU. Similar to the current provisions, the proposed LDAR 
provisions for PRDs require all PRDs that vent to the atmosphere be 
tested using EPA Method 21 to ensure the PRD is not leaking above the 
detection threshold during normal operation and to ensure it properly 
reseats if a release does occur. Those PRDs that vent to control 
systems would still be exempt from LDAR requirements given that if a 
release were to occur from this specific class of PRDs, it would vent 
to a closed vent system and control device.
    Finally, to ensure compliance with the proposed work practice 
standard for emissions released from PRD actuation events that vent 
directly to the atmosphere, we are also proposing to require that 
sources monitor these PRDs using a system that is capable of 
identifying and recording the time and duration of each pressure 
release and of notifying operators that a pressure release is 
occurring. Pressure release actuation events from PRDs that vent 
directly to the atmosphere have the potential to emit large quantities 
of HAP. When a pressure release occurs, it is important to identify and 
mitigate it as quickly as possible. We are proposing to allow owners 
and operators to use a range of methods to satisfy the PRD actuation 
detection requirements, including the use of a parameter monitoring 
system (that may already be in place) on the process that is sufficient 
to indicate that a pressure release has occurred as well as record the 
time and duration of that pressure release. For the purposes of 
estimating the costs of this requirement, we assume that all PRDs that 
would become subject to the proposed standards already have a process 
or parameter monitoring system that will indicate the time that a 
pressure release has occurred and the duration of the release.
    As part of these proposed provisions, we are proposing to add 
definitions for ``pressure release actuation event'' and ``pressure 
relief device or valve,'' to 40 CFR part 63, subpart GGGGG. We are also 
proposing to remove the definition of ``safety device'' and the 
provisions related to safety devices from 40 CFR part 63, subpart 
GGGGG, which would overlap and be redundant with parts of the proposed 
definition of ``pressure relief device or valve'' and the provisions 
related to these devices. To our knowledge, pressure relief devices or 
valves are the only relevant safety devices used in site remediation 
processes.
    The Agency recognizes that the treatment of PRDs should be 
appropriate to the characteristics of the relevant source category and 
need not be

[[Page 46155]]

uniform across all source categories. In developing this proposal, the 
EPA was mindful of the limited information it has with respect to PRDs 
in site remediation and the diversity of site characteristics. The EPA 
seeks comment on whether there are PRDs associated with affected 
facility process vents, tanks, containers, separators, or closed vent 
systems, and whether PRDs associated with those affected facilities are 
routed to a control device through a closed vent system or vent to the 
atmosphere. The EPA seeks comment on whether facilities that are 
subject to the Site Remediation NESHAP are also subject to EPA's CAP at 
40 CFR part 68, OSHA's Process Safety Management rule at 29 CFR 
1910.119, BAAQMD Rule 8-28-304, or SCAQMD Rule 1173, and if the latter 
set of rules extend to cover PRDs associated with site remediation. The 
EPA has proposed MACT work practice standards for PRDs that vent to the 
atmosphere based on the best performing sources that are subject to the 
other similar NESHAP (40 CFR part 63, subpart CC-Petroleum Refineries, 
and 40 CFR part 63, subpart DD--Offsite Waste and Recovery Operations). 
The EPA seeks comment on whether these MACT work practice standards for 
PRDs are appropriate for site remediation.
    For the purposes of estimating the costs of this requirement, we 
have assumed that operators have existing systems that are capable of 
identifying a pressure release to the atmosphere and recording the time 
and duration of the event. The EPA has further assumed there is one PRD 
per site remediation facility, and one pressure event every 3 years 
that would cause the PRD to actuate, triggering an analysis of the 
cause of the pressure release actuation event and the need for 
corrective measures. The EPA seeks comment on these assumptions. 
(Comment C-2) Whether or not data and comments substantiate that there 
are currently PRDs at site remediation facilities, the EPA may adopt 
provisions addressing PRDs if we conclude that future site-remediation 
affected facilities may use these devices.
    For further details on the assumptions and methodologies used in 
this analysis, see the technical memorandum titled Review of Regulatory 
Alternatives for Certain Vent Streams in the Site Remediation Source 
Category, which is in Docket ID No. EPA-HQ-OAR-2018-0833.

B. What are the results of the risk assessment and analyses for 
affected sources?

    As described above, for the Site Remediation source category, we 
conducted an inhalation risk assessment for all HAP emitted, a 
multipathway screening assessment for the PB-HAP emitted, and an 
environmental risk screening assessment for the PB-HAP and acid gases 
(e.g., HCl) emitted from affected sources. We present results of the 
risk assessment briefly below and in more detail in the Residual Risk 
Assessment for the Site Remediation Source Category in Support of the 
2019 Risk and Technology Review Proposed Rule, which is available in 
the docket for this action.
1. Chronic Inhalation Risk Assessment Results
    The results of the chronic baseline inhalation cancer risk 
assessment indicate that, based on estimates of current actual and 
allowable emissions, the MIR posed by the Site Remediation source 
category is 1-in-1 million driven by site remediation model plant 
emissions of arsenic compounds and chromium (VI) compounds. The total 
estimated cancer incidence based on actual and allowable emission 
levels is 0.001 excess cancer cases per year, or 1 case every 1,000 
years. The population exposed to cancer risks greater than or equal to 
1-in-1 million considering actual and allowable emissions is 400 (see 
Table 2 of this preamble). In addition, the maximum chronic noncancer 
HI (TOSHI) is less than 1.

                                    Table 2--Site Remediation Inhalation Risk Assessment Results for Affected Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Estimated
                                                   Maximum         population at     Estimated annual
          Number of facilities \1\                individual       increased risk    cancer incidence   Maximum chronic      Maximum  screening acute
                                               cancer risk  (in  of cancer  >=1-in-  (cases per year)   noncancer TOSHI            noncancer HQ
                                                  1 million)         1 million
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Based on Actual Emissions Level \2\ \3\
                                             -----------------------------------------------------------------------------------------------------------
102.........................................                  1                400              0.001                0.1  HQREL = 1
                                                                                                                          (arsenic compounds).
                                             -----------------------------------------------------------------------------------------------------------
                                                                                   Based on Whole Facility Emissions
                                             -----------------------------------------------------------------------------------------------------------
                                                          1,000          2,300,000                0.5                  5  ..............................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\3\ Actual emissions equal allowable emissions; therefore, actual risks equal allowable risks.

2. Screening Level Acute Risk Assessment Results
    As presented in Table 2 of this preamble, acute exposure to 
emissions from affected sources in the Site Remediation source category 
result in a maximum HQ of 1 based on the REL for arsenic compounds. For 
more detailed acute risk results refer to the Residual Risk Assessment 
for the Site Remediation Source Category in Support of the 2019 Risk 
and Technology Review Proposed Rule, which is available in the docket 
for this action.
3. Multipathway Risk Screening Results
    The results of the multipathway risk screening assessment indicate 
all Tier 2 screening values for PB-HAP emitted from the source category 
(arsenic compounds, cadmium compounds, mercury compounds, and POM) are 
less than 1. Based on these results, we are confident that the cancer 
risks due to multipathway exposures to these chemicals are lower than 
1-in-1 million and the noncancer HIs are less than 1.
    In the case of lead, the multipathway risks were assessed by 
comparing modeled ambient lead concentrations against the primary NAAQS 
for lead. The results of this analysis indicate that, based on actual 
and allowable emissions, the maximum annual off-site ambient lead 
concentration is 0.0001 [micro]g/m\3\, well below the primary NAAQS of 
0.15 [micro]g/m\3\.

[[Page 46156]]

4. Environmental Risk Screening Results
    The ecological risk screening assessment indicated all modeled 
points were below the Tier 1 screening thresholds based on actual and 
allowable emissions of PB-HAP (arsenic compounds, cadmium compounds, 
mercury compounds, and POM) and acid gases (HCl and HF) emitted by the 
source category.
    In the case of lead, the environmental risks were assessed by 
comparing modeled ambient lead concentrations against the secondary 
NAAQS for lead. The results of this analysis indicate that, based on 
actual and allowable emissions, the maximum annual off-site ambient 
lead concentrations were below the secondary NAAQS.
    Based on the results of the environmental risk screening 
assessment, we would not expect environmental risks due to emissions 
from this source category.
5. Facility-Wide Risk Results
    An assessment of whole-facility (or ``facility-wide) risks was 
performed as described above to characterize the source category risk 
in the context of facility-wide risks.\21\ Facility-wide risks were 
estimated using the NEI-based data. The maximum lifetime individual 
cancer risk posed by the 102 facilities, based on facility-wide 
emissions, is 1,000-in-1 million, with ethylene oxide emissions from 
facility-wide flares, transfer racks, vents, and fugitive emissions 
driving the risk. The total estimated cancer incidence based on whole 
facility emissions is 0.5 excess cancer cases per year, or one excess 
case in every 2 years. Approximately 2,300,000 people are estimated to 
have cancer risks above 1-in-1 million from facility-wide HAP 
emissions. Facility-wide lifetime individual cancer risks are estimated 
to be greater than or equal to 100-in-1 million at three facilities and 
55,000 people would be exposed at or above this risk level. Additional 
details on this determination can be found in the Residual Risk 
Assessment for the Site Remediation Source Category in Support of the 
2019 Risk and Technology Proposed Rule, which is available in the 
docket for this action.
---------------------------------------------------------------------------

    \21\ The facility-wide risk assessment includes all emission 
points within the Site Remediation source category (including those 
for which there are no standards) as well as other emission points 
covered by other NESHAP.
---------------------------------------------------------------------------

    Regarding the facility-wide risks due to ethylene oxide (described 
above), which are due to emission sources that are not part of the Site 
Remediation source category, we intend to evaluate those facility-wide 
estimated emissions and risks further and may address these in a 
separate future action, as appropriate. In particular, the EPA is 
addressing ethylene oxide based on the results of the latest NATA 
released in August 2018, which identified the chemical as a potential 
concern in several areas across the country. (NATA is the Agency's 
nationwide air toxics screening tool, designed to help the EPA and 
state, local, and tribal air agencies identify areas, pollutants, or 
types of sources for further examination.) The latest NATA estimates 
that ethylene oxide significantly contributes to potential elevated 
cancer risks in some census tracts across the U.S. (less than 1 percent 
of the total number of tracts). These elevated risks are largely driven 
by an EPA risk value that was updated in late 2016. The EPA will work 
with industry and state, local, and tribal air agencies as the EPA 
takes a two-pronged approach to address ethylene oxide emissions: (1) 
Reviewing and, as appropriate, revising CAA regulations for facilities 
that emit ethylene oxide--starting with air toxics emissions standards 
for miscellaneous organic chemical manufacturing facilities and 
commercial sterilizers; and (2) conducting site-specific risk 
assessments and, as necessary, implementing emission control strategies 
for targeted high-risk facilities. The EPA will post updates on its 
work to address ethylene oxide on its website at: https://www.epa.gov/ethylene-oxide. Regarding the noncancer risk assessment, the maximum 
chronic noncancer HI associated with facility-wide emissions is 
estimated to be 5 due to natural gas external combustion boiler 
emissions of chlorine. A total of three facilities had a facility-wide 
chronic noncancer HI greater than 1; two due to emissions of chlorine 
and one due to emissions of trichloroethylene.
6. What demographic groups might benefit from this regulation?
    To examine the potential for any environmental justice issues that 
might be associated with the source category, we performed a 
demographic analysis, which is an assessment of risk to individual 
demographic groups of the populations living within 5 km and within 50 
km of the facilities. In the analysis, we evaluated the distribution of 
HAP-related cancer and noncancer risk from the Site Remediation source 
category across different demographic groups within the populations 
living near facilities.\22\
---------------------------------------------------------------------------

    \22\ Demographic groups included in the analysis are: White, 
African American, Native American, Hispanic or Latino, other races 
and multiracial, people living below the poverty level, people 
living above the poverty level, adults without a high school 
diploma, adults with a high school diploma, and linguistically 
isolated people.
---------------------------------------------------------------------------

    The results of the demographic analysis are summarized in Table 3 
below. These results, for various demographic groups, are based on the 
estimated risk from actual emissions levels for the population living 
within 50 km of the facilities.

               Table 3--Site Remediation: Demographic Assessment Results--50 km Study Area Radius
----------------------------------------------------------------------------------------------------------------
                                                                             Population with
                                                                              cancer risk at    Population with
                                                             Nationwide      or above 1-in-1    chronic hi above
                                                                              million due to     1 due to site
                                                                             site remediation     remediation
----------------------------------------------------------------------------------------------------------------
Total Population.......................................        317,746,049                374                  0
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White..................................................                 62                 83                  0
Minority...............................................                 38                 17                  0
----------------------------------------------------------------------------------------------------------------
                                               Minority by Percent
----------------------------------------------------------------------------------------------------------------
African American.......................................                 12                 14                  0
Native American........................................                0.8                0.4                  0

[[Page 46157]]

 
Hispanic or Latino (includes white and nonwhite).......                 18                  0                  0
Other and Multiracial..................................                  7                  2                  0
----------------------------------------------------------------------------------------------------------------
                                                Income by Percent
----------------------------------------------------------------------------------------------------------------
Below Poverty Level....................................                 14                 13                  0
Above Poverty Level....................................                 86                 87                  0
----------------------------------------------------------------------------------------------------------------
                                              Education by Percent
----------------------------------------------------------------------------------------------------------------
Over 25 and without High School Diploma................                 14                 11                  0
Over 25 and with a High School Diploma.................                 86                 89                  0
----------------------------------------------------------------------------------------------------------------
                                       Linguistically Isolated by Percent
----------------------------------------------------------------------------------------------------------------
Linguistically Isolated................................                  6                  0                  0
----------------------------------------------------------------------------------------------------------------

    The results of the Site Remediation source category demographic 
analysis indicate that emissions from the source category expose 
approximately 400 people to a cancer risk at or above 1-in-1 million 
and no people to a chronic noncancer TOSHI greater than 1. The 
percentages of the at-risk population in each demographic group (except 
for White) are similar to or lower than their respective nationwide 
percentages with the exception of the African American, Above Poverty 
Level, and Over 25 and with a High School Diploma demographic groups, 
which are slightly higher than their respective nationwide percentages.
    The methodology and the results of the demographic analysis are 
presented in a technical report, Risk and Technology Review--Analysis 
of Demographic Factors for Populations Living Near Site Remediation 
Source Category Operations, available in the docket for this action.

C. What are our proposed decisions regarding risk acceptability, ample 
margin of safety, and adverse environmental effect?

1. Risk Acceptability
    We weigh all health risk factors in our risk acceptability 
determination, including the cancer MIR, the number of persons in 
various cancer and noncancer risk ranges, cancer incidence, the maximum 
noncancer TOSHI, the maximum acute noncancer HQ, the extent of 
noncancer risk, the distribution of cancer and noncancer risks in the 
exposed population, and risk estimation uncertainties (54 FR 38044, 
September 14, 1989).
    For the Site Remediation source category, the risk analysis 
indicates that for affected sources, the cancer risk to the individual 
most exposed is 1-in-1 million from both actual and allowable 
emissions. These risks are considerably less than 100-in-1 million, 
which is the presumptive upper limit of acceptable risk. The risk 
analysis for affected sources also estimated a cancer incidence of 
0.001 excess cancer cases per year, or 1 case every 1,000 years. 
Exposures to HAP with noncancer health effects are estimated to result 
in a maximum chronic noncancer TOSHI below 1 (0.1), as well as a 
maximum acute HQ value of 1. Multipathway screening values for affected 
sources are below a level of concern for both carcinogenic and non-
carcinogenic PB-HAP as well as emissions of lead compounds. Considering 
all the health risk information and factors discussed above, including 
the uncertainties, we propose to find that risk from the affected 
facilities in the Site Remediation source category subject to the Site 
Remediation NESHAP is acceptable.
2. Ample Margin of Safety Analysis
    Under the ample margin of safety analysis, we evaluated the cost 
and feasibility of available control technologies and other measures 
(including the controls, measures, and costs reviewed under the 
technology review) that could be applied in this source category to 
further reduce the risks (or potential risks) due to emissions of HAP.
    As discussed above, we are proposing that the risks from this 
source category are acceptable. For affected sources, the maximum 
cancer risk to the individual most exposed is 1-in-1 million from both 
actual and allowable emissions from site remediation processes and 
activities. Of the affected sources, two facilities had cancer risks 
equal to 1-in-1 million. Neither of these facilities had site 
remediation emissions reported to the NEI, and instead risks for both 
were based on estimated emissions.
    In our ample margin of safety analysis, we identified three control 
options that could further reduce HAP emissions from the source 
category. We evaluated those options to determine whether any of the 
three options is required to provide an ample margin of safety to 
protect public health. For process vents at affected sources, as 
discussed in section IV.D of this preamble, we identified an emissions 
control option requiring compliance with a 98-percent reduction rather 
than a 95-percent reduction in HAP emissions. To assess the maximum 
potential for risk reduction that could result from this process vent 
control option, we assumed that the maximum risks for the site 
remediation source category are due to emissions from a process vent 
with emissions controlled at 95-percent. In this scenario, we estimate 
that compliance with a requirement that process vents be 98-percent 
controlled could result in reducing source category HAP emissions by 
between 0.09 and 0.18 tpy from current emissions levels, with an 
incremental cost effectiveness ranging between $1 million to $2 
million/ton HAP reduction (section IV.D of this preamble provides 
further discussion of the EPA's cost analysis). We estimate this option 
would reduce the MIR at the MACT-allowable emissions level for the 
source category from 1-in-1 million to 0.4-in-1 million, thus, would 
reduce the number of people with cancer risks

[[Page 46158]]

greater than or equal to 1-in-1 million from 400 to 0. Although the 
maximum chronic noncancer TOSHI was less than 1, this option would 
further reduce it from 0.1 to 0.04. We are proposing that the 
considerable cost of this option is not reasonable in light of the 
minimal risk reduction achieved. Considering all of the health risks 
and other health information considered in our determination of risk 
acceptability, the minimal risk reductions associated with this option, 
the uncertainty associated with the estimated potential risk 
reductions, and the costs associated with this option, we are proposing 
that additional HAP emissions controls for site remediation process 
vents are not necessary to provide an ample margin of safety to protect 
public health.
    For equipment leaks at affected sources, as discussed in section 
IV.D of this preamble, we identified two emission control options: 
Option 1 would require the use of the leak detection thresholds of 40 
CFR part 63, subpart UU for valves and pumps, rather than the 
thresholds of 40 CFR part 63, subpart TT; Option 2 would require the 
same as Option 1 but would also include the connector LDAR requirements 
of 40 CFR part 63, subpart UU. Since actual and MACT-allowable 
emissions from equipment leaks are estimated to be the same, the risk 
due to equipment leaks at the MACT-allowable level are estimated to be 
the same as risk due to equipment leaks at actual emissions levels. In 
addition, based on our analysis of estimated baseline equipment leak 
emissions,\23\ we assumed that half of the equipment leak emissions are 
from non-connector components (i.e., pumps and valves), and the other 
half are from connectors. Under Option 1, we estimate the HAP reduction 
would be 4.7 tpy from the baseline actual emissions level, with a cost 
effectiveness of $2,000/ton HAP reduction. However, baseline risks 
associated with equipment leaks are low, and there would be little 
change in any of the risk metrics under Option 1. This option would 
reduce the MIR from 1-in-1 million to 0.8-in-1 million, and reduce the 
maximum chronic noncancer TOSHI from 0.1 to 0.08. In the context of our 
ample margin of safety analysis, we are proposing that imposing this 
option is not reasonable in light of the minimal risk reduction 
achieved. Although this option is not required to provide an ample 
margin of safety to protect public health, we are proposing this option 
as a cost-effective development under our technology review. Under 
Option 2 for equipment leaks, we estimate the incremental HAP reduction 
would be 5 tpy more than Option 1, with an overall cost effectiveness 
of $19,000/ton HAP reduction and a cost effectiveness incremental to 
Option 1 of $35,000/ton HAP reduction. Similar to option 1, we found 
that the control measure would provide little change to the estimated 
risks, but at even higher cost. Therefore, we are proposing that the 
cost of the Option 2 standards is not reasonable when weighed against 
the minimal risk reduction achieved.
---------------------------------------------------------------------------

    \23\ See Technology Review and Cost Impacts for the Proposed 
Amendments to the Off-Site Waste and Recovery Operations Source 
Category, which is available in the docket for this action.
---------------------------------------------------------------------------

    In accordance with the approach established in the Benzene NESHAP, 
the EPA weighed all health risk measures and information considered in 
the risk acceptability determination, along with the costs of emissions 
controls and technological feasibility, in making our ample margin of 
safety determination. Considering the health risk information and the 
little potential for risk reduction from control options identified for 
this source category, as well as the high relative cost of that risk 
reduction, we propose that the standards for the Site Remediation 
source category provide an ample margin of safety to protect public 
health. We request comments on the ample margin of safety analysis for 
this source category.
3. Adverse Environmental Effect
    Considering the results of our environmental risk screening, we do 
not expect an adverse environmental effect as a result of HAP emissions 
from this source category, and we are proposing that it is not 
necessary to set a more stringent standard to prevent, taking into 
consideration costs, energy, safety, and other relevant factors, an 
adverse environmental effect.

D. Additional Modeling for Site Remediation

    In addition to assessing risk from affected facilities, we also 
conducted an inhalation risk assessment for all HAP emitted, a 
multipathway screening assessment for the PB-HAP emitted, and an 
environmental risk screening assessment for the PB-HAP and acid gases 
(e.g., HCl) emitted from the CERCLA/RCRA exempt sources. Although 
exempt from the regulatory requirements of the Site Remediation NESHAP, 
these facilities are part of the Site Remediation source category. To 
understand the risks from the facilities exempt from the Site 
Remediation NESHAP requirements, these facilities were analyzed 
separately for the purposes of the risk assessment. We present results 
of the risk assessment briefly below and in more detail in the Residual 
Risk Assessment for Exempt Sources in the Site Remediation Source 
Category in Support of the 2019 Risk and Technology Review Proposed 
Rule, which is available in the docket for this action.
1. Chronic Inhalation Risk Assessment Results
    The results of the chronic baseline inhalation cancer risk 
assessment indicate that, based on estimates of current actual and 
allowable emissions, the MIR posed by exempt sources in the Site 
Remediation source category is 4-in-1 million driven by site 
remediation model plant emissions of chromium (VI) compounds. The total 
estimated cancer incidence based on actual and allowable emission 
levels is 0.001 excess cancer cases per year, or 1 case every 1,000 
years. The population exposed to cancer risks greater than or equal to 
1-in-1 million considering actual and allowable emissions is 1,100 (see 
Table 4 of this preamble). In addition, the maximum chronic noncancer 
HI (TOSHI) is less than 1.

[[Page 46159]]

                                 Table 4--Site Remediation Sources Inhalation Risk Assessment Results for Exempt Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                  Estimated
                                                                Maximum         population at     Estimated annual                     Maximum screening
                 Number of facilities \1\                  individual cancer  increased risk of   cancer incidence   Maximum chronic    acute noncancer
                                                               risk (in 1      cancer >=1-in-1    (cases per year)   noncancer TOSHI           HQ
                                                                million)           million
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        Based on Actual Emissions Level 2 3
                                                          ----------------------------------------------------------------------------------------------
118......................................................                  4              1,100              0.001                0.3                 <1
                                                          ----------------------------------------------------------------------------------------------
                                                                                         Based on Whole Facility Emissions
                                                          ----------------------------------------------------------------------------------------------
                                                                       2,000          9,000,000                  1                  7  .................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk due to HAP emissions from exempt sources in the source category.
\3\ Actual emissions equal allowable emissions; therefore, actual risks equal allowable risks.

2. Screening Level Acute Risk Assessment Results
    As presented in Table 4 of this preamble, acute exposure to 
emissions from exempt sources in the Site Remediation source category 
result in a maximum HQ less than 1. For more detailed acute risk 
results refer to the Residual Risk Assessment for Exempt Sources in the 
Site Remediation Source Category in Support of the 2019 Risk and 
Technology Review Proposed Rule, which is available in the docket for 
this action.
3. Multipathway Risk Screening Results
    The results of the multipathway risk screening assessment indicate 
all Tier 2 screening values for PB-HAP emitted from exempt sources in 
the source category (arsenic compounds, cadmium compounds, mercury 
compounds, and POM) are less than 1. Based on these results, we are 
confident that the cancer risks due to multipathway exposures to these 
chemicals are lower than 1-in-1 million and the noncancer HIs are less 
than 1.
    In the case of lead, the multipathway risks were assessed by 
comparing modeled ambient lead concentrations against the primary NAAQS 
for lead. The results of this analysis indicate that, based on actual 
and allowable emissions, the maximum annual off-site ambient lead 
concentration is 0.004 [micro]g/m\3\, well below the primary NAAQS of 
0.15 [micro]g/m\3\.
4. Environmental Risk Screening Results
    The ecological risk screening assessment indicated all modeled 
points were below the Tier 1 screening thresholds based on actual and 
allowable emissions of PB-HAP (arsenic compounds, cadmium compounds, 
mercury compounds, and POM) and acid gases (HCl and HF) emitted by 
exempt sources in the source category.
    In the case of lead, the environmental risks were assessed by 
comparing modeled ambient lead concentrations against the secondary 
NAAQS for lead. The results of this analysis indicate that, based on 
actual and allowable emissions, the maximum annual off-site ambient 
lead concentrations were below the secondary NAAQS.
    Based on the results of the environmental risk screening 
assessment, we would not expect environmental risks due to emissions 
from these sources.
5. Facility-Wide Risk Results
    An assessment of whole-facility (or ``facility-wide'') risks was 
performed as described above to characterize the exempt source risk in 
the context of facility-wide risks.\24\ Facility-wide risks were 
estimated using the NEI-based data. The maximum lifetime individual 
cancer risk posed by the 118 facilities, based on facility-wide 
emissions, is 2,000-in-1 million with ethylene oxide from facility-wide 
flare emissions driving the risk. The total estimated cancer incidence 
from the whole facility is one excess cancer case per year. 
Approximately 9,000,000 people are estimated to have cancer risks above 
1-in-1 million from facility-wide HAP emissions. Eleven facilities and 
98,000 people have facility-wide lifetime individual cancer risk 
greater than or equal to 100-in-1 million. Additional details on this 
determination can be found in the Residual Risk Assessment for 
Facilities Exempt from the Site Remediation Source Category in Support 
of the 2019 Risk and Technology Proposed Rule, which is available in 
the docket for this action.
---------------------------------------------------------------------------

    \24\ The facility-wide risk assessment includes all emission 
points from exempt facilities within the Site Remediation source 
category (including those for which there are no standards) as well 
as other emission points covered by other NESHAP.
---------------------------------------------------------------------------

    Regarding the facility-wide risks from exempt facilities due to 
ethylene oxide (described above), which are due to emission sources 
that are not part of the Site Remediation source category, we intend to 
evaluate those facility-wide estimated emissions and risks further and 
may address these in a separate future action, as appropriate. In 
particular, the EPA is addressing ethylene oxide based on the results 
of the latest NATA released in August 2018, which identified the 
chemical as a potential concern in several areas across the country. 
(NATA is the Agency's nationwide air toxics screening tool, designed to 
help the EPA and state, local, and tribal air agencies identify areas, 
pollutants, or types of sources for further examination.) The latest 
NATA estimates that ethylene oxide significantly contributes to 
potential elevated cancer risks in some census tracts across the U.S. 
(less than 1 percent of the total number of tracts). These elevated 
risks are largely driven by an EPA risk value that was updated in late 
2016. The EPA will work with industry and state, local, and tribal air 
agencies as the EPA takes a two-pronged approach to address ethylene 
oxide emissions: (1) Reviewing and, as appropriate, revising CAA 
regulations for facilities that emit ethylene oxide--starting with air 
toxics emissions standards for miscellaneous organic chemical 
manufacturing facilities and commercial sterilizers; and (2) conducting 
site-specific risk assessments and, as necessary, implementing emission 
control strategies for targeted high-risk facilities. The EPA will post 
updates on its work to address ethylene oxide on its website at: 
https://www.epa.gov/ethylene-oxide.
    Regarding the noncancer risk assessment, the maximum chronic 
noncancer HI associated with facility-wide emissions is estimated to be 
7 due to chemical manufacturing wastewater treatment emissions of 
chlorine. A total of eight facilities had a facility-wide

[[Page 46160]]

chronic noncancer HI greater than 1 due to emissions of one or more of 
the following HAP: chlorine; 2,4-toluene diisocyanate; hexamethylene-
1,6-diisocyanate; acrolein; propionaldehyde; acetaldehyde; and 
benzo[a]pyrene.
    As discussed in section VI.A.1 of this preamble, we are not 
proposing requirements for facilities exempt from the emissions control 
requirements of the Site Remediation NESHAP in this action.

E. What are the results and proposed decisions based on our technology 
review?

    As described in section III.B of this preamble, our technology 
review focused on identifying developments in practices, processes, and 
control technologies for the emission sources in the Site Remediation 
source category. To identify such developments since the MACT standards 
were promulgated, we consulted the EPA's RBLC, reviewed subsequent 
regulatory development efforts, reviewed major source operating permits 
and minor and synthetic minor source operating permits, and reviewed 
academic and trade literature for control technologies used in the 
industry.
    For the Site Remediation source category, we did not identify any 
developments in practices, processes, or control technologies for 
storage tanks, containers, surface impoundments, oil-water separators, 
organic-water separators, transfer systems, land treatment, or material 
extraction activities beyond what is currently required in the rule. 
For process vents and equipment leaks, we identified additional control 
options, and the following sections summarize the results of our 
technology review for these emissions sources.
    To perform the technology review, we needed information that was 
not included in the RTR emissions dataset used for modeling site 
remediation risks. Specifically, to evaluate the costs and cost 
effectiveness of various control options, we used a model plant 
approach for development of estimates for leaking components. This 
model plant analysis is not comparable to the model plant approach used 
in the risk analysis. The model plant for the technology review created 
the basis for evaluating the options of revising the LDAR standards. We 
model the number of potential leaking components, the leak rates 
applicable to such plants, and the level of emissions from leaking 
components under different standards. The component count and leak 
rates are the basis for evaluating the relative costs and benefits of 
changes that were considered for the LDAR program. Therefore, the model 
plant approach we used resulted in baseline emission estimates 
different from those included in the risk modeling dataset, which 
included its own inventory of emissions due to leaks. Additional 
information about our technology review and model plant approach can be 
found in the memorandum titled CAA section 112(d)(6) Technology Review 
for the Site Remediation Source Category, which is available in the 
docket for this action.
1. Process Vents
    The current Site Remediation MACT standards at 40 CFR 63.7890 
require emissions from process vents at existing and new affected 
sources to be routed through a closed vent system to a control device 
achieving at least 95-percent control. While some control devices, such 
as carbon adsorption, are assumed to have a control efficiency of 95-
percent, other technologies are capable of achieving greater emissions 
control, such as thermal oxidizers. Several of these devices have been 
demonstrated to achieve a control efficiency of 98-percent or greater. 
Based on the combination of reported control efficiencies for these 
devices and known application to low concentration organic vapor gas 
streams, we investigated the use of a catalytic thermal oxidizer with a 
control efficiency of 98-percent as a potential control option.
    Table 5 presents the emission reductions and costs of the 98-
percent control option considered for process vents at existing 
affected sources in the Site Remediation source category under the 
technology review. Data collected through our search of title V permits 
indicate that only some facilities have process vents, and based on 
these data, we estimate that approximately six site remediation 
facilities have process vents that would require additional control to 
reduce emissions by 98 percent. As site remediations vary in the amount 
and type of contamination that is being abated, we used two example 
remediations to estimate the amount of HAP that could be removed 
through the emissions controls. We estimated the capital and annual 
costs of complying with an increase from 95- to 98-percent HAP control 
for process vents to be the same for either example, with total capital 
costs estimated at approximately $400,000 and the total annualized 
costs estimated to be approximately $185,000. Based on the two example 
facilities, the HAP emissions reduction beyond the current control 
requirements could range between 0.09 and 0.18 tpy for the source 
category, and the cost effectiveness could range from approximately 
$31,000 to $66,000. The incremental cost effectiveness in going to 98-
percent control from 95-percent control could range from approximately 
$1 million to $2 million per ton HAP removed.

                                       Table 5--Site Remediation Process Vent Option Emission Reductions and Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                            Incremental
                                                                          HAP  emissions                                       Cost            cost
                 Regulatory alternative                       Example        reduction     Capital cost     Annual cost    effectiveness   effectiveness
                                                             facility          (tpy)            ($)           ($/yr)        ($/ton HAP      ($/ton HAP
                                                                                                                             removed)        removed)
--------------------------------------------------------------------------------------------------------------------------------------------------------
98-percent control......................................               1            0.09         400,000         185,000          65,000       2,145,000
                                                                       2            0.18         400,000         185,000          30,000       1,000,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on our estimate of costs and HAP reduction, we do not 
consider increasing the emission reduction to 98-percent to be 
reasonable, and we are not proposing to revise the Site Remediation 
MACT standards for process vents pursuant to CAA section 112(d)(6) to 
require this level of emissions control. We solicit comment on our 
analysis and conclusion regarding all aspects of this control option 
(Comment C-3).
2. Equipment Leaks
    The Site Remediation MACT standards at 40 CFR 63.7920 currently 
require compliance with either 40 CFR part 63, subpart TT, or 40 CFR 
part 63, subpart UU, to control emissions from equipment leaks at 
existing and new affected sources. While many provisions of these two 
standards are the same or similar, 40 CFR part 63, subpart UU, requires 
the use of a more stringent leak definition for valves in gas and vapor

[[Page 46161]]

service and in light liquid service, pumps in light liquid service, and 
connectors. Specifically, 40 CFR part 63, subpart UU, lowers the leak 
definition for valves from 10,000 ppm (in 40 CFR part 63, subpart TT) 
to 500 ppm, lowers the leak definition for pump seals from 10,000 ppm 
(in 40 CFR part 63, subpart TT) to 1,000 ppm, and requires periodic 
instrument monitoring of connectors with a leak definition of 500 ppm, 
as opposed to instrument monitoring only being required if a potential 
leak is detected by visual, audible, olfactory, or other detection 
method (in 40 CFR part 63, subpart TT). We identified the more 
stringent leak definitions of 40 CFR part 63, subpart UU as a 
development in practices, processes, or control technologies. The more 
stringent definitions have, in the years since original promulgation of 
the Site Remediation NESHAP in 2003, become widely adopted and are 
frequently already required for sources in the Site Remediation source 
category under the other applicable NESHAP requirements at these 
sources. Making the more stringent level of leak detection more uniform 
across a facility will also enhance regulatory consistency, clarity, 
and certainty and enhance compliance.
    Assuming conservatively that each of the site remediation 
facilities currently complies with 40 CFR part 63, subpart TT and does 
not already comply with 40 CFR part 63, subpart UU, we analyzed the 
costs and emission reductions of two options: Option 1--requiring the 
use of the leak detection thresholds of 40 CFR part 63, subpart UU for 
valves and pumps; Option 2--requiring the use of the leak detection 
thresholds of 40 CFR part 63, subpart UU for valves and pumps and, in 
addition, requiring connector monitoring under 40 CFR part 63, subpart 
UU. The estimated costs and emissions reductions associated with these 
two options for the site remediation source category are shown in Table 
6. For Option 1 (40 CFR part 63, subpart UU valve and pump leak 
detection thresholds), we estimated the capital costs to be 
approximately $26,000 and the total annualized costs to be 
approximately $10,000. The estimated HAP emissions reduction is 
approximately 4.7 tpy, and the cost effectiveness is approximately 
$2,000/ton. For Option 2 (40 CFR part 63, subpart UU valve and pump 
leak detection thresholds and connector monitoring), we estimated the 
capital costs to be approximately $95,000 and the total annualized 
costs to be approximately $188,000. The estimated HAP emissions 
reduction is approximately 9.7 tpy, and the cost effectiveness is 
approximately $19,000/ton. The incremental cost effectiveness between 
Option 1 and Option 2 is approximately $35,000.

                 Table 6--Site Remediation Equipment Leak Options Emission Reductions and Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                    Incremental
                                  HAP  emissions                                       Cost            cost
     Regulatory alternatives         reduction     Capital cost     Annual cost    effectiveness   effectiveness
                                       (tpy)            ($)           ($/yr)        ($/ton HAP      ($/ton HAP
                                                                                     removed)        removed)
----------------------------------------------------------------------------------------------------------------
Option 1: 40 CFR part 63,                    4.7          26,000          10,000           2,000  ..............
 subpart UU valve and pump leak
 thresholds only................
Option 2: 40 CFR part 63,                    9.7          95,000         188,000          19,000          35,000
 subpart UU valve and pump leak
 detection thresholds and
 connector monitoring...........
----------------------------------------------------------------------------------------------------------------

    Based on our analysis, the costs of Option 1 are reasonable, given 
the level of HAP emissions reduction that would be achieved with this 
control option. We do not believe the costs of Option 2 are reasonable, 
given the level of HAP emissions reduction it would achieve relative to 
a much higher incremental cost per ton above Option 1. Therefore, we 
are proposing to revise the Site Remediation MACT standards in 
accordance with Option 1 for equipment leaks. We solicit comment on our 
assessment and conclusions regarding all aspects of both options 
(Comment C-4).

F. What other actions are we proposing?

    In addition to the proposed actions described above, we are 
proposing additional revisions to the NESHAP, and requesting 
information on two issues for which the EPA has been petitioned for 
reconsideration. We are proposing revisions to the SSM provisions of 
the MACT rule in order to ensure that they are consistent with the 
Court decision in Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008), 
which vacated two provisions that exempted sources from the requirement 
to comply with otherwise applicable CAA section 112(d) emission 
standards during periods of SSM. We also are proposing various other 
changes to require electronic reporting of emissions test results and 
to make several minor technical corrections to the regulation text of 
40 CFR part 63, subpart GGGGG. Our analyses and proposed changes 
related to these issues are discussed below.
1. Standards for Inorganic HAP and Metal Emissions
    In the May 13, 2016, proposal on reconsideration, the EPA stated 
that it would consider the issue of regulating metals and inorganic HAP 
emissions during the risk review. 81 FR 29824. The EPA is proposing to 
not set standards for metals and inorganic HAP from site remediation 
sources subject to the Site Remediation NESHAP because we do not have 
data indicating that remediation sources subject to the rule emit these 
pollutants. In the EPA's development of the risk modeling emissions 
data, we found six facilities with emissions data in the NEI that were 
labeled under the SCC as being from a site remediation. None of these 
facilities reported inorganic HAP emissions or metal emissions. The EPA 
is, therefore, proposing no action at this time to set standards for 
inorganic HAP and metals in the absence of data indicating such 
emissions occur at affected facilities. The EPA is requesting data 
demonstrating whether or not any affected site remediation sources emit 
inorganic HAP or metals (Comment C-5).
2. SSM
a. Background
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. 
Cir. 2008), the Court vacated portions of two provisions in the EPA's 
CAA section 112 regulations governing the emissions of HAP during 
periods of SSM. Specifically, the Court vacated the SSM exemption 
contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1) holding that under 
section 302(k) of the CAA, emissions standards or limitations must be 
continuous in nature and that the SSM exemption violates the CAA's 
requirement that a section 112 standard apply at all times.

[[Page 46162]]

    We are proposing to eliminate the SSM exemption in the Site 
Remediation NESHAP. Consistent with Sierra Club v. EPA, we are 
proposing standards in this rule that apply at all times. We are also 
proposing several revisions to Table 3 (the General Provisions 
Applicability Table) as is explained in more detail below. For example, 
we are proposing to eliminate the incorporation of the General 
Provisions' requirement that the source develop an SSM plan. We also 
are proposing to eliminate and revise certain recordkeeping and 
reporting requirements related to the SSM exemption as further 
described below.
    The EPA has attempted to eliminate provisions that are 
inappropriate, unnecessary, or redundant in the absence of the SSM 
exemption in this proposal. We are specifically seeking comment on 
whether we have successfully done so (Comment C-6).
    In proposing the standards in this rule, the EPA has taken into 
account startup and shutdown periods and, for the reasons explained 
below, has not proposed alternate standards for those periods.
    Based on the types of site remediation processes and equipment for 
this source category, the EPA has assumed that emissions during periods 
of startup and shutdown are the same as or lower than during normal 
operations. As it is possible to stop processing remediation material 
until any control devices are fully operating and able to effectively 
control emissions, the EPA has determined that separate standards for 
periods of startup and shutdown are not necessary and are not being 
proposed. We solicit comment on this conclusion regarding periods of 
startup and shutdown at site remediation facilities (Comment C-7).
    Periods of startup, normal operations, and shutdown are all 
predictable and routine aspects of a source's operations. However, by 
contrast, malfunction is defined as a ``sudden, infrequent, and not 
reasonably preventable failure of air pollution control and monitoring 
equipment, process equipment or a process to operate in a normal or 
usual manner. . .'' (40 CFR 63.2). The EPA has determined that CAA 
section 112 does not require that emissions that occur during periods 
of malfunction be factored into development of CAA section 112 
standards. Under CAA section 112, emissions standards for new sources 
must be no less stringent than the level ``achieved'' by the best 
controlled similar source and for existing sources generally must be no 
less stringent than the average emission limitation ``achieved'' by the 
best performing 12 percent of sources in the category. There is nothing 
in CAA section 112 that directs the EPA to consider malfunctions in 
determining the level ``achieved'' by the best performing sources when 
setting emission standards. As the Court has recognized, the phrase 
``average emissions limitation achieved by the best performing 12 
percent of sources'' says nothing about how the performance of the best 
units is to be calculated. Nat'l Ass'n of Clean Water Agencies v. EPA, 
734 F.3d 1115, 1141 (D.C. Cir. 2013). While the EPA accounts for 
variability in setting emissions standards, nothing in CAA section 112 
requires the EPA to consider malfunctions as part of that analysis. A 
malfunction should not be treated in the same manner as the type of 
variation in performance that occurs during routine operations of a 
source. A malfunction is a failure of the source to perform in a 
``normal or usual manner'' and no statutory language compels the EPA to 
consider such events in setting standards based on ``best performers.''
    Further, accounting for malfunctions in setting emissions standards 
would be difficult, if not impossible, given the myriad different types 
of malfunctions that can occur across all sources in the category and 
given the difficulties associated with predicting or accounting for the 
frequency, degree, and duration of various malfunctions that might 
occur. As such, the performance of units that are malfunctioning is not 
``reasonably'' foreseeable. See, e.g., Sierra Club v. EPA, 167 F.3d 
658, 662 (D.C. Cir. 1999) (``EPA typically has wide latitude in 
determining the extent of data-gathering necessary to solve a problem. 
We 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.'' '') (internal quotation omitted). See 
also Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) (``In 
the nature of things, no general limit, individual permit, or even any 
upset provision can anticipate all upset situations. After a certain 
point, the transgression of regulatory limits caused by `uncontrollable 
acts of third parties,' such as strikes, sabotage, operator 
intoxication or insanity, and a variety of other eventualities, must be 
a matter for the administrative exercise of case-by-case enforcement 
discretion, not for specification in advance by regulation.''). In 
addition, the goal of a ``best controlled or best performing source'' 
is to operate in such a way as to avoid malfunctions of the source and 
accounting for malfunctions could lead to standards that are 
significantly less stringent than levels that are achieved by a well-
performing non-malfunctioning source. It is reasonable to interpret CAA 
section 112 to avoid such a result. The EPA's approach to malfunctions 
is consistent with CAA section 112 and is a reasonable interpretation 
of the statute.
    In the event that a source fails to comply with the applicable CAA 
section 112(d) standards as a result of a malfunction event, the EPA 
would determine an appropriate response based on, among other things, 
the good faith efforts of the source to minimize emissions during 
malfunction periods, including preventative and corrective actions, as 
well as root cause analyses to ascertain and rectify excess emissions. 
The EPA would also consider whether the source's failure to comply with 
the CAA section 112(d) standard was, in fact, ``sudden, infrequent, not 
reasonably preventable'' and was not instead ``caused in part by poor 
maintenance or careless operation.'' 40 CFR 63.2 (definition of 
malfunction). Further, to the extent the EPA files an enforcement 
action against a source for violation of an emission standard, the 
source can raise any and all defenses in that enforcement action, and 
the federal district court will determine what, if any, relief is 
appropriate. The same is true for citizen enforcement actions. 
Similarly, the presiding officer in an administrative proceeding can 
consider any defense raised and determine whether administrative 
penalties are appropriate.
    In several prior rules, the EPA had included an affirmative defense 
to civil penalties for violations caused by malfunctions in an effort 
to create a system that incorporates some flexibility, recognizing that 
there is a tension, inherent in many types of air regulations, to 
ensure adequate compliance, while simultaneously recognizing that 
despite the most diligent of efforts, emission standards may be 
violated under circumstances entirely beyond the control of the source. 
Although the EPA recognized that its case-by-case enforcement 
discretion provides sufficient flexibility in these circumstances, it 
included the affirmative defense to provide a more formalized approach 
and more regulatory clarity. Compare Weyerhaeuser Co. v. Costle, 590 
F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an informal case-by-
case enforcement discretion approach is adequate) with Marathon Oil Co. 
v. EPA, 564 F.2d 1253, 1272-73 (9th Cir. 1977) (requiring a more 
formalized approach to consideration of ``upsets beyond the control of 
the permit holder.''). Under

[[Page 46163]]

the EPA's regulatory affirmative defense provisions, if a source could 
demonstrate in a judicial or administrative proceeding that it had met 
the requirements of the affirmative defense in the regulation, civil 
penalties would not be assessed. In 2014, the Court vacated such an 
affirmative defense in one of the EPA's CAA section 112(d) regulations. 
NRDC v. EPA, 749 F.3d 1055 (D.C. Cir. 2014) (vacating affirmative 
defense provisions in a CAA section 112(d) rule establishing emission 
standards for Portland cement kilns). The Court found that the EPA 
lacked authority to establish an affirmative defense for private civil 
suits and held that under the CAA, the authority to determine civil 
penalty amounts lies exclusively with the courts, not the EPA. 
Specifically, the Court found, ``As the language of the statute makes 
clear, the courts determine, on a case-by-case basis, whether civil 
penalties are `appropriate.' '' 749 F.3d at 1063; see also Id. 
(``[U]nder this statute, deciding whether penalties are `appropriate' 
in a given private civil suit is a job for the courts, not EPA.''). In 
light of NRDC, the EPA is not including a regulatory affirmative 
defense provision in this proposed rule. As explained above, if a 
source is unable to comply with emissions standards as a result of a 
malfunction, the EPA may use its case-by-case enforcement discretion to 
provide flexibility, as appropriate. Further, as the Court recognized, 
in an EPA or citizen enforcement action, the court has the discretion 
to consider any defense raised and determine whether penalties are 
appropriate. See Id. at 1064 (noting arguments that violation were 
caused by unavoidable technology failure can be made to the courts in 
future civil cases when the issue arises). The same logic applies to 
EPA administrative enforcement actions.
b. Specific SSM-Related Proposed Changes
    To address the United States Court of Appeals for the District of 
Columbia Circuit vacatur of portions of the EPA's CAA section 112 
regulations governing the emissions of HAP during periods of SSM, we 
are proposing revisions and additions to certain provisions of the Site 
Remediation NESHAP. As described in detail below, we are proposing to 
revise the General Provisions applicability table (Table 3 to 40 CFR 
part 63, subpart GGGGG) in several of the references related to 
requirements that apply during periods of SSM. We are also proposing 
revisions related to the following provisions of the Site Remediation 
NESHAP: (1) The general duty to minimize emissions at all times; (2) 
the requirement for sources to comply with the emission limits in the 
rule at all times; (3) performance testing conditions requirements; (4) 
excused monitoring excursions provisions; and (5) malfunction 
recordkeeping and reporting requirements.
(1.) General Duty
    We are proposing to revise the General Provisions table (Table 3) 
entry for 40 CFR 63.6(e) by adding rows specifically for 40 CFR 
63.6(e)(1)(i), 63.6(e)(1)(ii), and 63.6(e)(1)(iii), and to include a 
``no'' in the applicability column for the 40 CFR 63.6(e)(1)(i) entry. 
Section 63.6(e)(1)(i) describes the general duty to minimize emissions. 
Some of the language in that section is no longer necessary or 
appropriate in light of the elimination of the SSM exemption. We are 
proposing instead to add general duty regulatory text at 40 CFR 
63.7935(b) that reflects the general duty to minimize emissions while 
eliminating the reference to periods covered by an SSM exemption. The 
current language in 40 CFR 63.6(e)(1)(i) characterizes what the general 
duty entails during periods of SSM. With the elimination of the SSM 
exemption, there is no need to differentiate between normal operations, 
startup and shutdown, and malfunction events in describing the general 
duty. Therefore, the language the EPA is proposing for 40 CFR 
63.7935(b) does not include that language from 40 CFR 63.6(e)(1).
    We are also proposing to include a ``no'' in the applicability 
column for the newly added entry for 40 CFR 63.6(e)(1)(ii). Section 
63.6(e)(1)(ii) imposes requirements that are not necessary with the 
elimination of the SSM exemption or are redundant with the general duty 
requirement being added at 40 CFR 63.7935(b).
    The provisions of 40 CFR 63.6(e)(1)(iii) still apply, and we are 
keeping the ``yes'' in the applicability column for that section. For 
40 CFR 63.6(e)(2), we are proposing to include a ``no'' in the 
applicability column for that section because it is a reserved section 
in the General Provisions.
(2.) SSM Plan
    We are proposing to revise the General Provisions table (Table 3) 
entry for 40 CFR 63.6(e)(3) by changing the ``yes'' to ``no'' in the 
applicability column. Generally, this paragraph requires development of 
an SSM plan and specifies SSM recordkeeping and reporting requirements 
related to the SSM plan. As previously noted, the EPA is proposing to 
remove the SSM exemptions. Therefore, affected units will be subject to 
an emission standard during such events. The applicability of a 
standard during such events will ensure that sources have ample 
incentive to plan for and achieve compliance and, thus, the SSM plan 
requirements are no longer necessary.
(3.) Compliance With Standards
    We are proposing to revise the General Provisions table (Table 3) 
entry for 40 CFR 63.6(f)(1) by changing the ``yes'' in the 
applicability column to a ``no.'' The current language of 40 CFR 
63.6(f)(1) exempts sources from non-opacity standards during periods of 
SSM. As discussed above, the Court in Sierra Club vacated the 
exemptions contained in this provision and held that the CAA requires 
that some CAA section 112 standard apply at all times. Consistent with 
Sierra Club, the EPA is proposing to revise standards in this rule to 
apply at all times.
(4.) Performance Testing
    We are proposing to revise the General Provisions table (Table 3) 
entry for 40 CFR 63.7(e)(1) by changing the ``yes'' in the 
applicability column to a ``no.'' Section 63.7(e)(1) describes 
performance testing requirements. The EPA is instead proposing to add a 
performance testing requirement at 40 CFR 63.7941(b)(2). The 
performance testing requirements we are proposing to add differ from 
the General Provisions performance testing provisions in several 
respects. The regulatory text does not include the language in 40 CFR 
63.7(e)(1) that restated the SSM exemption. However, consistent with 40 
CFR 63.7(e)(1), performance tests conducted under this subpart should 
be based on representative performance (i.e., performance based on 
normal operating conditions) of the affected source. The EPA is 
proposing to add language that requires the owner or operator to record 
the process information that is necessary to document operating 
conditions during the test and include in such record an explanation to 
support that such conditions represent normal operation. Section 
63.7(e) requires that the owner or operator make available to the 
Administrator such records ``as may be necessary to determine the 
condition of the performance test'' upon request but does not 
specifically require the information to be recorded. The regulatory 
text the EPA is proposing to add to this provision builds on that 
requirement and makes explicit the requirement to record and report the 
information.

[[Page 46164]]

(5.) Monitoring
    We are proposing to revise the General Provisions table (Table 3) 
entries for 40 CFR 63.8(c)(1)(i) and (iii) by changing the ``yes'' in 
the applicability column to a ``no.'' The cross-references to the 
general duty and SSM plan requirements in those subparagraphs are not 
necessary in light of other requirements of 40 CFR 63.8 that require 
good air pollution control practices (40 CFR 63.8(c)(1)) and that set 
out the requirements of a quality control program for monitoring 
equipment (40 CFR 63.8(d)).
(6.) Recordkeeping
    We are proposing to revise the General Provisions table (Table 3) 
entry for 40 CFR 63.10(b)(2)(i)-(iv) by adding separate entries for 40 
CFR 63.10(b)(2)(i)-(ii), 63.10(b)(2)(iii) and 63.10(b)(2)(iv)-(v) and 
changing the ``yes'' in the applicability column to a ``no'' for 40 CFR 
63.10(b)(2)(i)-(ii) and 63.10(b)(2)(iv)-(v). Section 63.10(b)(2)(i) 
describes the recordkeeping requirements during startup and shutdown. 
These recording provisions are no longer necessary because the EPA is 
proposing that recordkeeping and reporting applicable to normal 
operations will apply to startup and shutdown. In the absence of 
special provisions applicable to startup and shutdown, such as a 
startup and shutdown plan, there is no reason to retain additional 
recordkeeping for startup and shutdown periods. Section 63.10(b)(2)(ii) 
describes the recordkeeping requirements during a malfunction. The EPA 
is proposing to add such requirements to 40 CFR 63.7952(a)(2). The 
regulatory text we are proposing to add differs from the General 
Provisions it is replacing in that the General Provisions require the 
creation and retention of a record of the occurrence and duration of 
each malfunction of process, air pollution control, and monitoring 
equipment. The EPA is proposing that this requirement apply to any 
failure to meet an applicable standard and is requiring that the source 
record the date, time, and duration of the failure rather than the 
``occurrence.'' The EPA is also proposing to add to 40 CFR 
63.7952(a)(2) a requirement that sources keep records that include a 
list of the affected source or equipment and actions taken to minimize 
emissions, an estimate of the volume of each regulated pollutant 
emitted over the standard for which the source failed to meet the 
standard, and a description of the method used to estimate the 
emissions. Examples of such methods would include mass balance 
calculations, measurements when available, or engineering judgment 
based on known process parameters. The EPA is proposing to require that 
sources keep records of this information to ensure that there is 
adequate information to allow the EPA to determine the severity of any 
failure to meet a standard, and to provide data that may document how 
the source met the general duty to minimize emissions when the source 
has failed to meet an applicable standard. Section 63.10(b)(2)(iv) 
requires sources to record actions taken during SSM events when actions 
were inconsistent with their SSM plan. The requirement is no longer 
appropriate because SSM plans will no longer be required. The 
requirement previously applicable under 40 CFR 63.10(b)(2)(iv)(B) to 
record actions to minimize emissions and record corrective actions is 
now applicable by reference to 40 CFR 63.7952(a)(2). Section 
63.10(b)(2)(v) requires sources to record actions taken during SSM 
events to show that actions taken were consistent with their SSM plan. 
The requirement is no longer appropriate because SSM plans will no 
longer be required.
(7.) Reporting
    We are proposing to revise the General Provisions table (Table 3) 
entry for 40 CFR 63.10(d)(5) by changing the ``yes'' in the 
applicability column to ``no.'' Section 63.10(d)(5)(i) describes the 
reporting requirements for startups, shutdowns, and malfunctions. To 
replace the General Provisions reporting requirements, the EPA is 
proposing to add electronic reporting requirements to 40 CFR 
63.7951(c). The replacement language differs from the General 
Provisions requirement in that it eliminates periodic SSM reports as a 
stand-alone report. We are proposing language that requires sources 
that fail to meet an applicable standard at any time to report the 
information concerning such events in the semi-annual summary report 
already required under this rule. We are proposing that the report must 
contain the number, date, time, duration, and the cause of such events 
(including unknown cause, if applicable), a list of the affected source 
or equipment, an estimate of the quantity of each regulated pollutant 
emitted over any emission limit, and a description of the method used 
to estimate the emissions.
    Examples of such methods would include mass balance calculations, 
measurements when available, or engineering judgment based on known 
process parameters. The EPA is proposing this requirement to ensure 
that there is adequate information to determine compliance, to allow 
the EPA to determine the severity of the failure to meet an applicable 
standard, and to provide data that may document how the source met the 
general duty to minimize emissions during a failure to meet an 
applicable standard.
    We will no longer require owners or operators to determine whether 
actions taken to correct a malfunction are consistent with an SSM plan, 
because plans would no longer be required. The proposed amendments, 
therefore, eliminate the cross-reference to 40 CFR 63.10(d)(5)(i) that 
contains the description of the previously required SSM report format 
and submittal schedule from this section. These specifications are no 
longer necessary because the events will be reported in otherwise 
required reports with similar format and submittal requirements.
    Section 63.10(d)(5)(ii) describes an immediate report for startups, 
shutdowns, and malfunctions when a source failed to meet an applicable 
standard but did not follow the SSM plan. We will no longer require 
owners and operators to report when actions taken during a startup, 
shutdown, or malfunction were not consistent with an SSM plan, because 
plans would no longer be required.
3. Electronic Reporting
    Through this proposal, the EPA is proposing that owners and 
operators of site remediation facilities submit electronic copies of 
required performance test reports, performance evaluation reports, and 
semi-annual compliance reports through the EPA's Central Data Exchange 
(CDX) using the Compliance and Emissions Data Reporting Interface 
(CEDRI). A description of the electronic data submission process is 
provided in the memorandum, Electronic Reporting Requirements for New 
Source Performance Standards (NSPS) and National Emission Standards for 
Hazardous Air Pollutants (NESHAP) Rules, available in Docket ID No. 
EPA-HQ-OAR-2018-0833. The proposed rule requires that performance test 
results collected using test methods that are supported by the EPA's 
Electronic Reporting Tool (ERT) as listed on the ERT website \25\ at 
the time of the test be submitted in the format generated through the 
use of the ERT and that other performance test results be submitted in 
portable document format (PDF) using the attachment module of

[[Page 46165]]

the ERT. Similarly, performance evaluation results of CMS measuring 
relative accuracy test audit pollutants that are supported by the ERT 
at the time of the test must be submitted in the format generated 
through the use of the ERT and other performance evaluation results be 
submitted in PDF using the attachment module of the ERT.
---------------------------------------------------------------------------

    \25\ https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert.
---------------------------------------------------------------------------

    For semi-annual summary compliance reports, the proposed rule 
requires that owners and operators use the appropriate spreadsheet 
template to submit information to CEDRI. A draft version of the 
proposed template for this report is included in the docket for this 
rulemaking.\26\ The EPA specifically requests comment on the content, 
layout, and overall design of the template.
---------------------------------------------------------------------------

    \26\ See 
40_CFR_Part_63_Subpart_GGGGG_Site_Remediation_Spreadsheet_Template_Dr
aft.xlsm, available at Docket ID No. EPA-HQ-OAR-2018-0833.
---------------------------------------------------------------------------

    Additionally, the EPA has identified two broad circumstances in 
which electronic reporting extensions may be provided. In both 
circumstances, the decision to accept the claim of needing additional 
time to report is within the discretion of the Administrator, and 
reporting should occur as soon as possible. The EPA is providing these 
potential extensions to protect owners and operators from noncompliance 
in cases where they cannot successfully submit a report by the 
reporting deadline for reasons outside of their control. The situation 
where an extension may be warranted due to outages of the EPA's CDX or 
CEDRI which precludes an owner or operator from accessing the system 
and submitting required reports is addressed in 40 CFR 63.7951(e). The 
situation where an extension may be warranted due to a force majeure 
event, which is defined as an event that will be or has been caused by 
circumstances beyond the control of the affected facility, its 
contractors, or any entity controlled by the affected facility that 
prevents an owner or operator from complying with the requirement to 
submit a report electronically as required by this rule is addressed in 
40 CFR63.7951(e). Examples of such events are acts of nature, acts of 
war or terrorism, or equipment failure or safety hazards beyond the 
control of the facility.
    The electronic submittal of the reports addressed in this proposed 
rulemaking will increase the usefulness of the data contained in those 
reports, is in keeping with current trends in data availability and 
transparency, will further assist in the protection of public health 
and the environment, will improve compliance by facilitating the 
ability of regulated facilities to demonstrate compliance with 
requirements, and by facilitating the ability of delegated state, 
local, tribal, and territorial air agencies and the EPA to assess and 
determine compliance, and will ultimately reduce burden on regulated 
facilities, delegated air agencies, and the EPA. Electronic reporting 
also eliminates paper-based, manual processes, thereby saving time and 
resources, simplifying data entry, eliminating redundancies, minimizing 
data reporting errors, and providing data quickly and accurately to the 
affected facilities, air agencies, the EPA, and the public. Moreover, 
electronic reporting is consistent with the EPA's plan \27\ to 
implement Executive Order 13563 and is in keeping with the EPA's 
Agency-wide policy \28\ developed in response to the White House's 
Digital Government Strategy.\29\ For more information on the benefits 
of electronic reporting, see the memorandum, Electronic Reporting 
Requirements for New Source Performance Standards (NSPS) and National 
Emission Standards for Hazardous Air Pollutants (NESHAP) Rules, 
available in Docket ID No. EPA-HQ-OAR-2018-0833.
---------------------------------------------------------------------------

    \27\ EPA's Final Plan for Periodic Retrospective Reviews, August 
2011. Available at: https://www.regulations.gov/document?D=EPA-HQ-OA-2011-0156-0154.
    \28\ E-Reporting Policy Statement for EPA Regulations, September 
2013. Available at: https://www.epa.gov/sites/production/files/2016-03/documents/epa-ereporting-policy-statement-2013-09-30.pdf.
    \29\ Digital Government: Building a 21st Century Platform to 
Better Serve the American People, May 2012. Available at: https://obamawhitehouse.archives.gov/sites/default/files/omb/egov/digital-government/digital-government.html.
---------------------------------------------------------------------------

4. Open-Ended Valves and Lines
    The Site Remediation NESHAP in 40 CFR 63.7920(b) requires an owner 
or operator to control emissions from equipment leaks according to the 
requirements of either 40 CFR part 63, subpart TT, or 40 CFR part 63, 
subpart UU. For open-ended valves and lines, both subpart TT in 40 CFR 
63.1014(b)(1) and subpart UU in 40 CFR 63.1033(b)(1) require that the 
open end be equipped with a cap, blind flange, plug, or second valve 
that shall ``seal the open end.'' However, ``seal'' is not defined in 
either subpart, leading to uncertainty for the owner or operator as to 
whether compliance is being achieved. Inspections under the EPA's Air 
Toxics LDAR initiative have provided evidence that while certain open-
ended lines may be equipped with a cap, blind flange, plug, or second 
valve, these are not providing a ``seal'' as the EPA interprets the 
term.\30\ In response to this uncertainty, we are proposing to amend 40 
CFR 63.7920(b) to clarify what ``seal the open end'' means for open-
ended valves and lines. This proposed clarification explains that for 
the purpose of complying with the requirements of 40 CFR 63.1014(b)(1) 
(subpart TT), and 40 CFR 63.1033(b)(1) (subpart UU), open-ended valves 
and lines are ``sealed'' by the cap, blind flange, plug, or second 
valve if instrument monitoring of the open-ended valve or line 
conducted according to EPA Method 21 of 40 CFR part 60, appendix A 
indicates no readings of 500 ppm or greater.
---------------------------------------------------------------------------

    \30\ See Region V OEL Data for VV Rulemaking, available in the 
docket for this action, available at Docket ID No. EPA-HQ-OAR-2018-
0833.
---------------------------------------------------------------------------

    In addition, 40 CFR 63.1014(c) of subpart TT and 40 CFR 63.1033(c) 
of subpart UU exempt open-ended valves and lines that are in an 
emergency shutdown system, and which are designed to open 
automatically, from the requirements to be equipped with a cap, blind 
flange, plug, or second valve that seals the open end. We are proposing 
that these open-ended valves and lines follow the requirements of 40 
CFR 63.7920(b)(3)(ii) for bypass devices that could be used to divert a 
vent stream from the closed-vent system to the atmosphere, which would 
require that each such open-ended line be equipped with either a flow 
indicator or a seal or locking device. We are also proposing 
recordkeeping and reporting requirements in 40 CFR 63.7951(g)(3) and 40 
CFR 63.7952(a)(2)(v)(B) for these open-ended values and lines.
    We solicit comments on our proposed approach to reducing the 
compliance uncertainty associated with ``sealed'' open-ended valves and 
lines and our proposed requirements for open-ended valves and lines 
that are in an emergency shutdown system and are designed to open 
automatically (Comment C-8).
5. Technical Corrections
    In this rulemaking, we are proposing four technical corrections to 
improve the clarity of the Site Remediation NESHAP requirements.
    First, the original Site Remediation NESHAP, promulgated in October 
2003 (68 FR 58172), incorporated two voluntary consensus standards 
(VCS) by reference, as specified in 40 CFR 63.14. However, while the 
paragraphs in 40 CFR 63.14 for these three VCS include references to 
the NESHAP for which they are approved to be used, these references 
omit citations to 40 CFR 63, subpart GGGGG. In 40 CFR 63.14, we

[[Page 46166]]

are adding citations to 40 CFR 63.7944 for the two following consensus 
standards: American Petroleum Institute (API) Publication 2517, 
Evaporative Loss From External Floating-Roof Tanks, and American 
Society for Testing and Materials (ASTM) Method D2879-83.
    Second, we are correcting a citation reference to 40 CFR 63.7(3) in 
40 CFR 63.7942. The correct citation is to 40 CFR 63.7(a)(3).
    Third, we are correcting a citation reference to 40 CFR 
63.7890(a)(1)(i) in 40 CFR 63.7941. The correct citation is to 40 CFR 
63.7890(b).
    Fourth, we are correcting several citation references to 40 CFR 
63.7990 in 40 CFR 63.7901(a), 40 CFR 63.7901(b)(1), and 40 CFR 
63.7903(a) and (b). The correct citations are to 40 CFR 63.7900.

G. What compliance dates are we proposing?

    Under CAA section 112(d), the proposed compliance date for new and 
existing affected sources for the revised SSM requirements, electronic 
reporting requirements, the operating and pressure release management 
requirements for PRDs, and the revised requirements regarding bypasses 
and closure devices on pressure tanks is the effective date of the 
final amendments. We are proposing this compliance date because 
available information indicates these new and revised requirements 
should be immediately implementable by the facilities.
    We are proposing that for existing affected sources subject to the 
Site Remediation MACT standards, the compliance date for the PRD 
pressure release actuation event reporting requirements is 1 year from 
the effective date of the final amendments. This time is needed 
regardless of whether an owner or operator of a facility chooses to 
comply with the PRD pressure release actuation event reporting 
provisions by installing PRD release indicator systems, employing 
parameter monitoring, routing releases to a control device, or choosing 
another compliance option as permitted under the proposed provisions. 
This time period will allow site remediation facility owners and 
operators to research equipment and vendors, and to purchase, install, 
test, and properly operate any necessary equipment by the compliance 
date. For new affected sources, the proposed compliance date for PRD 
pressure release actuation event reporting requirements is the 
effective date of the final amendments.
    Finally, we are proposing revised requirements for equipment leaks 
under CAA section 112(d)(6). The EPA generally understands the steps 
needed for site remediation facilities to comply with the proposed 
standards for equipment leaks, and believes 1 year represents a 
reasonable amount of time it will take these facilities to take these 
steps. Therefore, we are proposing that a one-year compliance period 
from the date of promulgation is necessary for the revised equipment 
leak requirements to allow existing affected sources that are currently 
complying with 40 CFR part 63, subpart TT, adequate time to modify 
their existing LDAR programs to comply with the revised standards for 
pumps and valves. For new affected sources, the proposed compliance 
date for the equipment leak standards is the effective date of the 
final amendments.

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

    We estimate that there are approximately 63 major source site 
remediation facilities. Based on available permit information, 33 
facilities are expected to be subject to a limited set of the rule 
requirements under 40 CFR 63.7881(c)(1) due to the low annual quantity 
of HAP contained in the remediation material excavated, extracted, 
pumped, or otherwise removed during the site remediations conducted at 
the facilities. These facilities are only required to prepare and 
maintain written documentation to support the determination that the 
total annual quantity of the HAP contained in the remediation material 
excavated, extracted, pumped, or otherwise removed at the facility is 
less than 1 megagram per year. They are not subject to any other 
emissions limits, work practices, monitoring, reporting, or 
recordkeeping requirements. While new site remediations are likely to 
be conducted in the future, we are currently not aware of any specific 
new site remediation facilities that are expected to be constructed.

B. What are the air quality impacts?

    For equipment leaks, we are proposing to revise the equipment leak 
thresholds for pumps and valves for facilities complying with 40 CFR 
part 63, subpart TT. We estimate the HAP emission reduction for this 
change to be approximately 4.7 tpy. We do not anticipate any HAP 
emission reduction from our proposed clarification of the rule 
provision ``seal the open end'' (in the context of open-ended valves 
and lines) or the requirement to electronically report the results of 
emissions testing. For the proposed revisions to the MACT standards 
regarding SSM, including monitoring of PRDs in remediation material 
service, we were not able to quantify the possible emission reductions, 
so none are included in our assessment of air quality impacts.
    Therefore, the estimated total HAP emission reductions for the 
proposed rule revisions for the Site Remediation source category are 
estimated to be 4.7 tpy.

C. What are the cost impacts?

    For equipment leaks, we are proposing to revise the equipment leak 
thresholds for pumps and valves for facilities complying with 40 CFR 
part 63, subpart TT. We estimate the nationwide capital costs to be 
$26,000 and the annual costs to be $10,000.
    We do not anticipate any quantifiable capital or annual costs for 
our proposed requirements to electronically report the results of 
emissions testing, or the requirements to monitor PRDs. For PRDs, we 
are also proposing to require facilities to conduct analyses of the 
causes of PRD pressure release actuation events and to implement of 
corrective measures. We estimate the nationwide annualized costs for 
the analysis of actuation events to be $13,000. This cost represents 
the estimated labor hours we anticipate would be required to determine 
the cause of a typical actuation event and to implement any corrective 
measure suggested by the analysis of the cause. We estimate an increase 
in reporting and recordkeeping associated with the proposed 
requirements for equipment leaks and PRDs of approximately $7,000 per 
year nationwide. Therefore, the total capital costs for the proposed 
standards for the Site Remediation source category are approximately 
$26,000, and the total annualized costs are approximately $30,000.

D. What are the economic impacts?

    Economic impact analyses focus on changes in market prices and 
output levels. If changes in market prices and output levels in the 
primary markets are significant enough, impacts on other markets may 
also be examined. Both the magnitude of costs needed to comply with a 
proposed rule and the distribution of these costs among affected 
facilities can have a role in determining how the market will change in 
response to a proposed rule. The total capital costs associated with 
this proposed rule are estimated to be approximately $26,000, and the 
estimated annualized cost is approximately $30,000. We expect these 
costs to be borne by 30 facilities, with

[[Page 46167]]

an estimated annualized cost of approximately $1,000 per facility per 
year. These costs are not expected to result in a significant market 
impact, regardless of whether they are passed on to the purchaser or 
absorbed by the firms.

E. What are the benefits?

    We have estimated that this action will achieve HAP emissions 
reductions of 4.7 tpy. The proposed standards will result in reductions 
in the actual and MACT-allowable emissions of HAP and may reduce the 
actual and potential cancer risks and noncancer health effects due to 
emissions of HAP from this source category, as discussed in section 
IV.B.2 of this preamble. We have not quantified the monetary benefits 
associated with these reductions; however, these avoided emissions will 
result in improvements in air quality and reduced negative health 
effects associated with exposure to air pollution of these emissions.

VI. Request for Comment

A. Request for Comment Regarding CERCLA/RCRA Exempt Sources

1. Introduction
    The EPA is using this RTR proposal separately to solicit comment on 
ways in which the Site Remediation NESHAP could be amended with respect 
to facilities currently exempt under 40 CFR 63.7881(b)(2) and (3), 
under a scenario where the EPA removes the exemption. The exemption 
applies to facilities subject to federally-enforceable oversight under 
the CERCLA or the RCRA. In particular, in light of comments received on 
our 2016 proposal to remove the exemption, the Agency seeks additional 
comment regarding subcategorization or other methods of distinguishing 
among appropriate requirements for such sources, as well as whether the 
issues raised by commenters may be applicable more generally for all 
affected facilities in this source category. The EPA is seeking comment 
on how, if the exemption was removed, these formerly exempt sources 
would be able to implement the Site Remediation NESHAP effectively and 
efficiently while meeting the requirements of RCRA, CERCLA, and the 
CAA. We seek comment on how this could be reflected in the 
applicability, monitoring, recordkeeping, reporting, and compliance 
demonstration requirements. The EPA seeks comment on how to efficiently 
implement the rule for cleanups conducted under CERCLA or RCRA 
authority. For example, this could include look-up tables for commonly 
used remediation alternatives and associated BACT and LAER compliant 
technologies that would minimize emissions to be consistent with the 
rule. We are seeking ideas on what tools or metrics could be developed 
that would aid to streamline the implementation of the regulation on a 
site-specific basis.
    It is not the EPA's intention to take final action with respect to 
the exemption in this action, but to use this opportunity to gather 
additional information in anticipation of addressing these issues 
through a separate action (Comment C-9).
2. Background
    Section 112(c)(1) of the CAA requires EPA to publish and regularly 
update (at least every 8 years) ``a list of all categories and 
subcategories of major sources and area sources (listed under paragraph 
(3)) of the air pollutants listed pursuant to subsection (b).'' In 
1992, the EPA included site remediation on the initial CAA 112(c)(1) 
source category list and defined the source category to include the 
cleanup of sites that possess contaminated media, including National 
Priorities List sites and Corrective Action sites. See the EPA, July 
1992 Final Report. The listing assumed that remediation cleanups 
conducted under specific cleanup authorities could be major sources. 
Section 112(c)(2) of the CAA states that the EPA ``shall establish 
emissions standards under [section 112(d)]'' for the categories and 
subcategories the Administrator lists. The D.C. Circuit has described 
this as a mandatory obligation. See, e.g., NRDC v. EPA, 489 F.3d. 1364, 
1368 (2007).
3. Promulgation of Rule and Petition for Reconsideration
    In 2003, the EPA promulgated a final rule under CAA section 112 
which established MACT standards for HAP emissions at major sources 
where remediation technologies and practices are used to clean up 
contaminated media (e.g., soils, groundwater, or surface water) or 
certain stored or disposed materials (68 FR 58172, October 8, 2003). 
The rule exempted from the MACT standard remediations performed under 
federal oversight pursuant to CERCLA or the RCRA corrective action 
program, on the basis that such regulated cleanups provided the 
``functional equivalent'' of the MACT standards. Id. at 58176.
    The EPA stated that CERCLA Superfund and RCRA corrective action 
programs provide an ``appropriate and effective regulatory approach'' 
to address air emissions, because these statutes require consideration 
of the same HAP emissions and include a public input process. Id. at 
58183. EPA noted the RCRA corrective action and CERCLA Superfund 
assessment and clean-up processes are already subject to federal 
regulatory oversight; further, remediation actions are designed and 
managed based on site-specific conditions; and, they include public 
participation mechanisms. Id. Note that the EPA did not extend the RCRA 
and CERCLA exemption to sites handled under state and voluntary cleanup 
programs, brownfields cleanups, and other types of site remediation 
that are not subject to the oversight provided for RCRA corrective 
action or CERCLA Superfund actions, see Id. at 58183-84. The EPA 
concluded that imposing the NESHAP requirements on remediations already 
overseen pursuant to CERCLA or RCRA would have limited impact and could 
add administrative burden to the remediation process under those 
programs for little or no environmental benefit. Id.
    The Sierra Club filed a petition for judicial review of the rule in 
the Court as well as an administrative petition for reconsideration 
under the CAA on two issues in the final rule, one of which was the 
exemption for CERCLA and RCRA sites. The other issue raised by 
petitioners concerned control of heavy metals and other inorganic HAP 
from this source category. This issue is addressed in section IV.E.1 of 
this preamble. The petition for reconsideration stated that the public 
did not have an opportunity to comment specifically on the EPA's 
``functional equivalent'' argument because the EPA raised it for the 
first time in the final rule preamble. Petitioners further stated that 
there is no CAA authority to exempt these sources, and CAA section 
112(c) and (d) require that the EPA establish MACT standards for them. 
Petitioners asserted that CERCLA and RCRA applicable requirements are 
not the functional equivalent of the MACT standards for this source 
category, and that the EPA had not demonstrated that they are.
    In January 2004, the Court granted a joint motion to hold the case 
in abeyance so the parties could discuss possible settlement. 
Settlement discussions were ultimately unsuccessful. In October 2014, 
the Court ordered the parties to show cause why the case should not be 
administratively terminated. The EPA and Sierra Club filed a joint 
response stating that the parties were exploring a new approach to 
settlement. In March 2015, the EPA granted reconsideration on the 
issues raised in the petition via letter.

[[Page 46168]]

    In May 2016, the EPA proposed to remove the exemption from the Site 
Remediation MACT rule for CERCLA Superfund and RCRA corrective action 
sites (81 FR 29821 May 13, 2016). The EPA has not taken final action on 
the proposed rule, and the EPA now is seeking further comment and 
information relating to this issue.
4. 2016 Proposal on Reconsideration
    On May 13, 2016, the EPA proposed to amend the Site Remediation 
NESHAP by removing exemptions from the rule for site remediation 
activities performed under federally-enforceable oversight authority of 
CERCLA or RCRA. 81 FR 29821.The EPA also proposed removing the 
applicability requirement that site remediations be co-located with at 
least one other stationary source regulated by another NESHAP. The EPA 
has not taken final action on that proposal and is not proposing to do 
so in this notice. However, in conjunction with this proposal for the 
RTR, the EPA is seeking additional comment and information related to 
the EPA's previous proposal to remove the exemptions for remediations 
under RCRA and CERCLA programs. The EPA is not seeking further comment 
on the proposal to remove the applicability requirement that site 
remediations be co-located with at least one other stationary source 
regulated by another NESHAP.
    In response to our 2016 proposal, the EPA received comments both in 
support of and in opposition to our proposal to remove the exemption 
provisions. The EPA has reviewed the comments received in response to 
our 2016 proposal and does not believe it has sufficient information to 
proceed with a final rule at this time. The comments received in 
opposition to the proposal to remove the exemptions suggested that the 
proposal to remove the RCRA and CERCLA exemptions alone, without 
further consideration of modification of other provisions, may apply 
the NESHAP to sources that we did not intend to regulate, or apply the 
NESHAP in a way that compliance is impractical given the nature of the 
remediation effort facing the source.
    These comments, briefly summarized below (and available in the 
proposal docket at EPA-HQ-OAR-2002-0021), have led the EPA to determine 
that additional information and comment are appropriate before taking 
further action. The EPA is not proposing any regulatory action on 
removing the RCRA and CERCLA exemptions in this RTR proposal. Rather, 
the EPA is using this proposal as an opportune time to solicit further 
information and data in response to the comments on our prior proposal. 
The comments and information we receive with respect to the exemptions 
will be added to the information available for a subsequent rulemaking 
after the EPA has finalized the RTR.
5. Discussion and Request for Comment
    The 2016 proposal to eliminate the exemption included no other 
changes to the rule, although the proposal would have the effect of 
applying the rule to approximately 125 facilities at which a site 
remediation is conducted, an inclusion that would, in turn, cover an 
even greater number of operable units. The EPA received comments from 
facilities from across the spectrum of exempt sources likely to be 
subject to the rule after removing the exemptions. This broad range of 
sources and their diversity indicate that the EPA should consider sub-
categorization or other methods of differentiating among sources under 
the Site Remediation NESHAP.
    Under CAA section 112(c), the EPA may establish subcategories based 
on size, type, or class of affected source, such that standards 
applicable to each subcategory achieve reductions required by the CAA, 
but in a manner appropriate to that subgroup of sources. In general, 
the EPA has established subcategories based on the material inputs or 
the nature of the products being produced which in turn inform the 
nature of the requirements that apply. In other cases, the EPA created 
subcategories for different process equipment that required air 
pollution control of fundamentally different operating parameters and 
mechanisms, and which, in turn, required monitoring or testing of 
different types to demonstrate compliance.
    The EPA understands the comments on the May 2016 proposal to 
indicate that the EPA should consider subcategorizing or 
differentiating among remediations in some way. While the Site 
Remediation NESHAP already reflects certain differences in remedial 
actions, in commenters' view, there are other considerations that 
warrant further consideration of how the rule is structured.
    Commenters described the site remediation in ways that suggested 
that applying the Site Remediation NESHAP is unlike applying other 
NESHAP. For example, when a typical major source is constructed, the 
owner-operator is fully aware of the processes they will perform, the 
equipment that will be needed, and the techniques and practices that 
will be employed to comply with applicable standards. If a source is 
not able to determine applicability based on their own comparison of 
potentially applicable standards and their industrial processes, the 
facility can request an applicability determination from the EPA.
    In contrast, an entity that is initiating a site remediation must 
contend with a level of uncertainty and incomplete information about 
the remediation that eventually will occur. These differences have a 
material impact on the way sources determine applicability and 
implement specific provisions of the Site Remediation NESHAP. For 
example, 40 CFR 63.7886(c)(1) has provisions that require that a source 
conduct a site investigation to substantiate specific subsurface 
quantities of pollutants to be remediated, to determine whether a given 
remediation will be subject to the rule.
    To make this determination, the extent of contamination must be 
estimated, but these quantities may not be known until a future (and 
often extended) period for a single operable unit. This is further 
complicated when a facility consists of many individual operable units 
dispersed over hundreds of acres. A facility with a series of operable 
units that will be in remediation in sequence is not required to know 
the pollutant quantities at all operable units at the outset of the 
first remediation, unless the facility is compelled to make an 
applicability determination under the Site Remediation NESHAP. When 
remediating a series of operable units, the remediation activity across 
units may not be active at the same time or may be intermittent or 
discontinued after a couple of months or years. This makes an 
applicability determination for a potentially affected source a greater 
hurdle than the EPA may have considered.
    The EPA recognizes that the diversity of sites already subject to 
the NESHAP is a characteristic of the Site Remediation source category 
as a whole. However, we understand commenters' view to be that the size 
of the cleanup, and the typically greater scale, complexity, and 
diversity of remediation issues at sites that fall under the current 
RCRA and CERCLA exemption render the considerations discussed above 
particularly significant in establishing appropriate NESHAP 
requirements for such sites.
    Another consideration highlighted by commenters for these typically 
large and complex remediation sites is that remediation is driven by 
the requirements of the RCRA and CERCLA programs, not by compliance 
with a NESHAP. For some affected sources, according to commenters, 
compliance

[[Page 46169]]

with certain requirements of the rule may have a negative impact on the 
execution of remediation conducted in compliance with RCRA and CERCLA. 
For example, RCRA and CERCLA cleanups may be ongoing at the time that 
the remediation becomes subject to the Site Remediation NESHAP. While 
the EPA has some flexibility in the applicability date of the NESHAP, 
commenters pointed out that the EPA provided no regulatory language to 
guide a facility to show whether or how the facility's adherence to 
corrective action requirements and approved remediation plans under 
RCRA and CERCLA demonstrate initial or continuing compliance with the 
Site Remediation NESHAP standards to allow a remediation to proceed.
    The EPA will take these comments under advisement, to be acted upon 
at a later date. The EPA will proceed with the RTR notice and comment 
rulemaking to complete this requirement under CAA section 112 by the 
deadline. Please see sections IV.B and IV.D of this preamble, and 
technical support documents supplied in the docket, for how the EPA has 
evaluated exempt sources with respect to both the risk and technology 
reviews.

B. Request for Comment on All Aspects of the Risk and Technology Review

    We solicit comments on all aspects of this proposed action. In 
addition to general comments on this proposed action, we are also 
interested in additional data that may improve the risk assessments and 
other analyses. We are specifically interested in receiving any 
improvements to the data used in the site-specific emissions profiles 
used for risk modeling. Such data should include supporting 
documentation in sufficient detail to allow characterization of the 
quality and representativeness of the data or information. Section VII 
of this preamble provides more information on submitting data.

VII. Submitting Data Corrections

    The site-specific emissions profiles used in the source category 
risk and demographic analyses and instructions are available for 
download on the RTR website at https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html. The data files include detailed information for each HAP 
emissions release point for the facilities in the source category.
    If you believe that the data are not representative or are 
inaccurate, please identify the data in question, provide your reason 
for concern, and provide any ``improved'' data that you have, if 
available. When you submit data, we request that you provide 
documentation of the basis for the revised values to support your 
suggested changes. To submit comments on the data downloaded from the 
RTR website, complete the following steps:
    1. Within this downloaded file, enter suggested revisions to the 
data fields appropriate for that information.
    2. Fill in the commenter information fields for each suggested 
revision (i.e., commenter name, commenter organization, commenter email 
address, commenter phone number, and revision comments).
    3. Gather documentation for any suggested emissions revisions 
(e.g., performance test reports, material balance calculations).
    4. Send the entire downloaded file with suggested revisions in 
Microsoft[supreg] Access format and all accompanying documentation to 
Docket ID No. EPA-HQ-OAR-2018-0833 (through the method described in the 
ADDRESSES section of this preamble).
    5. If you are providing comments on a single facility or multiple 
facilities, you need only submit one file for all facilities. The file 
should contain all suggested changes for all sources at that facility 
(or facilities). We request that all data revision comments be 
submitted in the form of updated Microsoft[supreg] Excel files that are 
generated by the Microsoft[supreg] Access file. These files are 
provided on the RTR website at https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html.

VIII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was, 
therefore, not submitted to OMB for review.

B. Executive Order 13771: Reducing Regulation and Controlling 
Regulatory Costs

    This action is not expected to be an Executive Order 13771 
regulatory action because this action is not significant under 
Executive Order 12866.

C. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have 
been submitted for approval to OMB under the PRA. The Information 
Collection Request (ICR) document that the EPA prepared has been 
assigned EPA ICR number 2062.07. You can find a copy of the ICR in the 
docket for this rule, and it is briefly summarized here.
    The information requirements in this rulemaking are based on the 
notification, recordkeeping, and reporting requirements in the NESHAP 
General Provisions (40 CFR part 63, subpart A), which are mandatory for 
all operators subject to national emission standards. These 
notifications, reports, and records are essential in determining 
compliance, and are specifically authorized by CAA section 114 (42 
U.S.C. 7414). All information submitted to the EPA pursuant to the 
recordkeeping and reporting requirements for which a claim of 
confidentiality is made is safeguarded according to agency policies set 
forth in 40 CFR part 2, subpart B.
    Respondents/affected entities: Unlike a specific industry sector or 
type of business, the respondents potentially affected by this ICR 
cannot be easily or definitively identified. Potentially, the Site 
Remediation rule may be applicable to any type of business or facility 
at which a site remediation is conducted to clean up media contaminated 
with organic HAP when the remediation activities are performed, the 
authority under which the remediation activities are performed, and the 
magnitude of the HAP in the remediation material meets the 
applicability criteria specified in the rule. A site remediation that 
is subject to this rule potentially may be conducted at any type of 
privately-owned or government-owned facility at which contamination has 
occurred due to past events or current activities at the facility. For 
site remediation performed at sites where the facility has been 
abandoned and there is no owner, a government agency takes 
responsibility for the cleanup.
    Respondent's obligation to respond: Mandatory (42 U.S.C. 7414).
    Estimated number of respondents: 30 total for the source category. 
These facilities are already respondents and no facilities are expected 
to become respondents as a result of this proposed action.
    Frequency of response: Semiannual.
    Total estimated burden: 19,700 total hours (per year) for the 
source category, of which 310 hours are estimated as a result of this 
proposed action. Burden is defined at 5 CFR 1320.3(b).
    Total estimated cost: The total estimated cost of the rule is $1.39 
million (per year) for the source category. This includes $126,000 
total annualized capital or operation and maintenance costs. We 
estimate that $36,000 of the $126,000 in total annualized capital or 
operation and

[[Page 46170]]

maintenance costs is a result of this proposed action. Recordkeeping 
and reporting costs of approximately $7,000 estimated as a result of 
this action are included in the $1.39 million in total costs.
    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 the 
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
    Submit your comments on the Agency's need for this information, the 
accuracy of the provided burden estimates, and any suggested methods 
for minimizing respondent burden to the EPA using the docket identified 
at the beginning of this rule. You may also send your ICR-related 
comments to OMB's Office of Information and Regulatory Affairs via 
email to OIRA_submissions@omb.eop.gov, Attention: Desk Officer for the 
EPA. Since OMB is required to make a decision concerning the ICR 
between 30 and 60 days after receipt, OMB must receive comments no 
later than October 3, 2019. The EPA will respond to any ICR-related 
comments in the final rule.

D. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. The 
small entities subject to the requirements of this action are chemical 
and refining companies. The Agency has determined that two small 
entities, representing approximately 7 percent of the total number of 
entities subject to the proposal, may experience an impact of less than 
0.1 percent of revenues. Details of this analysis are presented in the 
docket for this action (Docket ID No. EPA-HQ-OAR-2018-0833).

E. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. This proposed rule 
imposes no enforceable duty on any state, local, or tribal governments, 
or the private sector.

F. Executive Oder 13132: Federalism

    This 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.

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

    This action does not have tribal implications, as specified in 
Executive Order 13175 (65 FR 67249, November 9, 2000). There are no 
site remediation facilities that are owned or operated by tribal 
governments. Thus, Executive Order 13175 does not apply to this action. 
The EPA specifically solicits comment on this proposed action from 
tribal officials.

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

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because the EPA does not believe the environmental health or safety 
risks addressed by this action present a disproportionate risk to 
children. Because the proposed rule amendments would result in reduced 
emissions of HAP and reduced risk to anyone exposed, the EPA believes 
that the proposed rule amendments would provide additional protection 
to children. More information on the source category's risk can be 
found in section IV of this preamble. The complete risk analysis 
results and the details concerning its development are presented in the 
memorandum entitled Residual Risk Assessment for the Site Remediation 
Source Category in Support of the 2019 Risk and Technology Review 
Proposed Rule, available in the docket for this action (Docket ID No. 
EPA-HQ-OAR-2018-0833).
    The public is invited to submit comments or identify peer-reviewed 
studies and data that assess effects of early life exposure to HAP 
emitted by site remediation facilities.

I. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211, because it is 
not a significant regulatory action under Executive Order 12866.

J. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR 
Part 51

    This action involves technical standards. The EPA is formalizing 
the incorporation of two technical standards that were included in the 
October 2003 rule for which the EPA had previously not formally 
requested the Office of the Federal Register to include in 40 CFR 63.14 
with a reference back to the sections in 40 CFR 63, subpart GGGGG. 
These two standards were already incorporated in 40 CFR 63.14 and were 
formally requested for other rules. These standards are API Publication 
2517, ``Evaporative Loss from External Floating-Roof Tanks,'' Third 
Edition, February 1989, and ASTM D2879-83, ``Standard Method for Vapor 
Pressure- Temperature Relationship and Initial Decomposition 
Temperature of Liquids by Isoteniscope.'' The API Publication 2517 is 
used to determine the maximum true vapor pressure of HAP in liquids 
stored at ambient temperature and is available to the public for free 
viewing online in the Read Online Documents section on API's website at 
https://publications.api.org. In addition to this free online viewing 
availability on API's website, hard copies and printable versions are 
available for purchase from API. The ASTM D2879-83 method is also used 
to determine the maximum true vapor pressure of HAP in liquids stored 
at ambient temperature, and it is available to the public for free 
viewing online in the Reading Room section on ASTM's website at https://www.astm.org/READINGLIBRARY/. Hardcopies and printable versions are 
also available for purchase from ASTM. Additional information can be 
found at http://www.api.org/and https://www.astm.org/Standard/standards-andpublications.html.

K. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action does not have disproportionately 
high and adverse human health or environmental effects on minority 
populations, low-income populations and/or indigenous peoples, as 
specified in Executive Order 12898 (59 FR 7629, February 16, 1994) 
because it increases the level of environmental protection for all 
affected populations without having any disproportionately high and 
adverse human health or environmental effects on any population, 
including any minority, low income, or indigenous populations.
    To gain a better understanding of the source category and near 
source populations, the EPA conducted a demographic analysis for site 
remediation facilities to identify any overrepresentation of minority, 
low income, or indigenous populations with cancer risks above 1-in-1 
million. This analysis only gives some indication of the prevalence of 
sub-populations that may be exposed to air pollution from the sources; 
it does not identify the demographic characteristics of the most

[[Page 46171]]

highly affected individuals or communities, nor does it quantify the 
level of risk faced by those individuals or communities. More 
information on the source category's risk can be found in section IV of 
this preamble. The complete demographic analysis results and the 
details concerning its development are presented in the memorandum 
titled Risk and Technology Review--Analysis of Demographic Factors for 
Populations Living Near Site Remediation Source Category Operations, 
available in the docket for this action (Docket ID No. EPA-HQ-OAR-2018-
0833).
    For the Site Remediation source category, the demographic analysis 
revealed that for some demographic categories, the percentage of people 
with cancer risks greater than or equal to 1-in-1 million is above 
their corresponding national averages of the amount of people in that 
demographic category. These demographic categories are ``African 
American,'' ``Above Poverty Level,'' and ``Over 25 and With a High 
School Diploma.'' The ratio of African Americans with a cancer risk 
greater than or equal to 1-in-1 million due to site remediation is 17 
percent higher than the national average percentage of people in that 
demographic category (14 percent versus 12 percent); the ratio of 
people living above the poverty line with a cancer risk greater than or 
equal to 1-in-1 million due to site remediation is 1 percent higher 
than the national average percentage of people in that demographic 
category (87 percent versus 86 percent); and the ratio of people over 
age 25 with a high school diploma with a cancer risk greater than or 
equal to 1-in-1 million due to site remediation is 3 percent higher 
than the national average percentage of people in that demographic 
category (89 percent versus 86 percent). However, as noted previously, 
risks from this source category were found to be acceptable for all 
populations.

List of Subjects in 40 CFR Part 63

    Environmental protection, Air pollution control, Hazardous 
substances, Incorporation by reference, Reporting and recordkeeping 
requirements.

     Dated: August 5, 2019.
Andrew R. Wheeler,
Administrator.

    For the reasons set forth in the preamble, the EPA proposes to 
amend 40 CFR part 63 as follows:

PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS 
FOR SOURCE CATEGORIES

0
1. The authority citation for part 63continues to read as follows:

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

0
2. Section 63.14 is amended by revising paragraphs (c)(1) and (h)(31) 
to read as follows:

Sec.  63.14  Incorporations by reference.

* * * * *
    (c) * * *
    (1) API Publication 2517, Evaporative Loss from External Floating-
Roof Tanks, Third Edition, February 1989, IBR approved for Sec. Sec.  
63.111, 63.1402, 63.2406 and 63.7944.
* * * * *
    (h) * * *
    (31) ASTM D2879-83, Standard Method for Vapor Pressure-Temperature 
Relationship and Initial Decomposition Temperature of Liquids by 
Isoteniscope, IBR approved for Sec. Sec.  63.111, 63.1402, 63.2406, 
63.7944, and 63.12005.
* * * * *

Subpart GGGGG--National Emission Standards for Hazardous Air 
Pollutants: Site Remediation

0
3. Section 63.7883 is amended by revising paragraphs (a), (b) 
introductory text, (c) introductory text, and (d) introductory text, 
and adding paragraph (f) to read as follows:

Sec.  63.7883   When do I have to comply with this subpart?

    (a) If you have an existing affected source, you must comply with 
each emission limitation, work practice standard, and operation and 
maintenance requirement in this subpart that applies to you no later 
than October 9, 2006, except as provided in paragraph (f) of this 
section.
    (b) If you have a new affected source that manages remediation 
material other than a radioactive mixed waste as defined in Sec.  
63.7957, then you must meet the compliance date specified in paragraph 
(b)(1) or (2) of this section, as applicable to your affected source, 
except as provided in paragraph (f) of this section.
* * * * *
    (c) If you have a new affected source that manages remediation 
material that is a radioactive mixed waste as defined in Sec.  63.7957, 
then you must meet the compliance date specified in paragraph (c)(1) or 
(2) of this section, as applicable to your affected source, except as 
provided in paragraph (f) of this section.
* * * * *
    (d) If your facility is an area source that increases its emissions 
or its potential to emit such that it becomes a major source of HAP as 
defined in Sec.  63.2, then you must meet the compliance dates 
specified in paragraphs (d)(1) and (2) of this section, except as 
provided in paragraph (f) of this section.
* * * * *
    (f) Sources must comply with the equipment leak requirements of 
Sec.  63.7920(b)(3) and (4) and the pressure relief device requirements 
of Sec.  63.7920(d) and (e) as specified in paragraphs (f)(1) and (2) 
of this section.
    (1) If the affected source's initial startup date is before [DATE 
OF PUBLICATION OF THE FINAL RULE IN THE Federal Register], you must 
comply with the equipment leak requirements of Sec.  63.7920(b)(3) and 
(4) and the pressure relief device requirements of Sec.  63.7920(d) and 
(e) of this subpart on or before [DATE ONE YEAR AFTER DATE OF 
PUBLICATION OF THE FINAL RULE IN THE Federal Register].
    (2) If the affected source's initial startup date is on or after 
[DATE OF PUBLICATION OF THE FINAL RULE IN THE Federal Register], you 
must comply with the equipment leak requirements of Sec.  63.7920(b)(3) 
and (4) and the pressure relief device requirements of Sec.  63.7920(d) 
and (e) of this subpart upon initial startup.
0
4. Section 63.7895 is amended by revising paragraph (c) to read as 
follows:

Sec.  63.7895   What emissions limitations and work practice standards 
must I meet for tanks?

* * * * *
    (c) If you use Tank Level 1 controls, you must install and operate 
a fixed roof according to the requirements in Sec.  63.902, with the 
exceptions specified in paragraphs (c)(1) and (2) of this section. As 
an alternative to using this fixed roof, you may choose to use one of 
Tank Level 2 controls in paragraph (d) of this section.
    (1) Where Sec.  63.902(c)(2) provides an exception for a spring-
loaded pressure-vacuum relief valve, conservation vent, or similar type 
of pressure relief device which vents to the atmosphere, only a 
conservation vent is eligible for the exception for the purposes of 
this subpart.
    (2) The provisions of Sec.  63.902(c)(3) do not apply for the 
purposes of this subpart.
* * * * *
0
5. Section 63.7896 is amended by revising paragraphs (c)(1) and (3) and 
(f)(1) to read as follows:

[[Page 46172]]

Sec.  63.7896   How do I demonstrate initial compliance with the 
emissions limitations and work practice standards for tanks?

* * * * *
    (c) * * *
    (1) Each tank using Tank Level 1 controls is equipped with a fixed 
roof and closure devices according to the requirements in Sec.  
63.902(b) and (c), with the exceptions specified in Sec.  63.7895(c)(1) 
and (2), and you have records documenting the design.
* * * * *
    (3) You will operate the fixed roof and closure devices according 
to the requirements in Sec.  63.902, with the exceptions specified in 
Sec.  63.7895(c)(1) and (2).
* * * * *
    (f) * * *
    (1) Each tank is equipped with a fixed roof and closure devices 
according to the requirements in Sec.  63.685(g), with the exceptions 
specified in Sec.  63.7895(c)(1) and (2), and you have records 
documenting the design.
* * * * *
0
6. Section 63.7898 is amended by revising paragraph (c)(1) to read as 
follows:

Sec.  63.7898   How do I demonstrate continuous compliance with the 
emissions limitations and work practice standards for tanks?

* * * * *
    (c) * * *
    (1) Operating and maintaining the fixed roof and closure devices 
according to the requirements in Sec.  63.902(c), with the exceptions 
specified in Sec.  63.7895(c)(1) and (2).
* * * * *
0
7. Section 63.7900 is amended by revising paragraphs (b)(1) through (3) 
introductory text, (c), and (d) to read as follows:

Sec.  63.7900   What emissions limitations and work practice standards 
must I meet for containers?

* * * * *
    (b) * * *
    (1) If the design capacity of your container is less than or equal 
to 0.46 m\3\, then you must use controls according to the standards for 
Container Level 1 controls as specified in Sec.  63.922, except that 
Sec.  63.922(d)(4) and (5) do not apply for the purposes of this 
subpart. As an alternative, you may choose to use controls according to 
either of the standards for Container Level 2 controls as specified in 
Sec.  63.923.
    (2) If the design capacity of your container is greater than 0.46 
m\3\, then you must use controls according to the standards for 
Container Level 2 controls as specified in Sec.  63.923, except that 
Sec.  63.923(d)(4) and (5) do not apply for the purposes of this 
subpart and except as provided for in paragraph (b)(3) of this section.
    (3) As an alternative to meeting the standards in paragraph (b)(2) 
of this section for containers with a capacity greater than 0.46 m\3\, 
if you determine that either of the conditions in paragraphs (b)(3)(i) 
or (ii) apply to the remediation material placed in your container, 
then you may use controls according to the standards for Container 
Level 1 controls as specified in Sec.  63.922, except that Sec.  
63.922(d)(4) and (5) do not apply for the purposes of this subpart.
* * * * *
    (c) At times when a container having a design capacity greater than 
0.1 m\3\ is used for treatment of a remediation material by a waste 
stabilization process as defined in Sec.  63.7957, you must control air 
emissions from the container during the process whenever the 
remediation material in the container is exposed to the atmosphere 
according to the standards for Container Level 3 controls as specified 
in Sec.  63.924, except that Sec.  63.924(d) does not apply for the 
purposes of this subpart. You must meet the emissions limitations and 
work practice standards in Sec.  63.7925 that apply to your closed vent 
system and control device.
    (d) As an alternative to meeting the requirements in paragraph (b) 
of this section, you may choose to use controls on your container 
according to the standards for Container Level 3 controls as specified 
in Sec.  63.924, except that Sec.  63.924(d) does not apply for the 
purposes of this subpart. You must meet the emissions limitations and 
work practice standards in Sec.  63.7925 that apply to your closed vent 
system and control device.
* * * * *
0
8. Section 63.7901 is amended by revising paragraphs (a), (b)(1), 
(c)(2), and (d)(3) to read as follows:

Sec.  63.7901   How do I demonstrate initial compliance with the 
emissions limitations and work practice standards for containers?

    (a) You must demonstrate initial compliance with the emissions 
limitations and work practice standards in Sec.  63.7900 that apply to 
your affected containers by meeting the requirements in paragraphs (b) 
through (e) of this section, as applicable to your containers.
    (b) * * *
    (1) You have determined the applicable container control levels 
specified in Sec.  63.7900 for the containers to be used for your site 
remediation.
* * * * *
    (c) * * *
    (2) You will operate each container cover and closure device 
according to the requirements in Sec.  63.922(d), except that Sec.  
63.922(d)(4) and (5) do not apply for the purposes of this subpart.
    (d) * * *
    (3) You will operate and maintain the container covers and closure 
devices according to the requirements in Sec.  63.923(d), except that 
Sec.  63.923(d)(4) and (5) do not apply for the purposes of this 
subpart.
* * * * *
0
9. Section 63.7903 is amended by revising paragraphs (a), (b) 
introductory text, (c)(1), and (d)(2) to read as follows:

Sec.  63.7903   How do I demonstrate continuous compliance with the 
emissions limitations and work practice standards for containers?

    (a) You must demonstrate continuous compliance with the emissions 
limitations and work practice standards in Sec.  63.7900 applicable to 
your affected containers by meeting the requirements in paragraphs (b) 
through (e) of this section.
    (b) You must demonstrate continuous compliance with the requirement 
to determine the applicable container control level specified in Sec.  
63.7900(b) for each affected tank by meeting the requirements in 
paragraphs (b)(1) through (3) of this section.
* * * * *
    (c) * * *
    (1) Operating and maintaining covers for each container according 
to the requirements in Sec.  63.922(d), except that Sec.  63.922(d)(4) 
and (5) do not apply for the purposes of this subpart.
* * * * *
    (d) * * *
    (2) Operating and maintaining container covers according to the 
requirements in Sec.  63.923(d), except that Sec.  63.923(d)(4) and (5) 
do not apply for the purposes of this subpart.
* * * * *
0
10. Section 63.7905 is amended by revising paragraphs (b)(1) and (2) to 
read as follows:

Sec.  63.7905   What emissions limitations or work practice standards 
must I meet for surface impoundments?

* * * * *
    (b) * * *
    (1) Install and operate a floating membrane cover according to the 
requirements in Sec.  63.942, except that Sec.  63.942(c)(2) and (3) do 
not apply for the purposes of this subpart; or
    (2) Install and operate a cover vented through a closed vent system 
to a control device according to the requirements in Sec.  63.943, 
except that

[[Page 46173]]

Sec.  63.943(c)(2) does not apply for the purposes of this subpart. You 
must meet the emissions limitations and work practice standards in 
Sec.  63.7925 that apply to your closed vent system and control device.
* * * * *
0
11. Section 63.7906 is amended by revising paragraphs (b)(2) and (c)(2) 
to read as follows:

Sec.  63.7906   How do I demonstrate initial compliance with the 
emissions limitations or work practice standards for surface 
impoundments?

* * * * *
    (b) * * *
    (2) You will operate the cover and closure devices according to the 
requirements in Sec.  63.942(c), except that Sec.  63.942(c)(2) and (3) 
do not apply for the purposes of this subpart.
* * * * *
    (c) * * *
    (2) You will operate the cover and closure devices according to the 
requirements in Sec.  63.943(c), except that Sec.  63.943(c)(2) does 
not apply for the purposes of this subpart.
* * * * *
0
12. Section 63.7908 is amended by revising paragraphs (b)(1) and (c)(1) 
to read as follows:

Sec.  63.7908   How do I demonstrate continuous compliance with the 
emissions limitations and work practice standards for surface 
impoundments?

* * * * *
    (b) * * *
    (1) Operating and maintaining the floating membrane cover and 
closure devices according to the requirements in Sec.  63.942(c), 
except that Sec.  63.942(c)(2) and (3) do not apply for the purposes of 
this subpart.
* * * * *
    (c) * * *
    (1) Operating and maintaining the cover and its closure devices 
according to the requirements in Sec.  63.943(c), except that Sec.  
63.943(c)(2) does not apply for the purposes of this subpart.
* * * * *
0
13. Section 63.7910 is amended by revising paragraphs (b)(1) through 
(3) to read as follows:

Sec.  63.7910   What emissions limitations and work practice standards 
must I meet for separators?

* * * * *
    (b) * * *
    (1) Install and operate a floating roof according to the 
requirements in Sec.  63.1043, except that Sec.  63.1043(c)(2) does not 
apply for the purposes of this subpart. For portions of the separator 
where it is infeasible to install and operate a floating roof, such as 
over a weir mechanism, you must comply with the requirements specified 
in paragraph (b)(2) of this section.
    (2) Install and operate a fixed roof vented through a closed vent 
system to a control device according to the requirements in Sec.  
63.1044, except that Sec.  63.1044(c)(2) does not apply for the 
purposes of this subpart. You must meet the emissions limitations and 
work practice standards in Sec.  63.7925 that apply to your closed vent 
system and control device.
    (3) Install and operate a pressurized separator according to the 
requirements in Sec.  63.1045 except that Sec.  63.1045(b)(3)(i) does 
not apply for the purposes of this subpart.
* * * * *
0
14. Section 63.7911 is amended by revising paragraphs (b)(2), (c)(2), 
and (d)(2) to read as follows:

Sec.  63.7911   How do I demonstrate initial compliance with the 
emissions limitations and work practice standards for separators?

* * * * *
    (b) * * *
    (2) You will operate the floating roof and closure devices 
according to the requirements in Sec.  63.1043(c), except that Sec.  
63.1043(c)(2) does not apply for the purposes of this subpart.
* * * * *
    (c) * * *
    (2) You will operate the fixed roof and its closure devices 
according to the requirements in Sec.  63.1042(c), except that Sec.  
63.1042(c)(2) does not apply for the purposes of this subpart.
* * * * *
    (d) * * *
    (2) You will operate the pressurized separator as a closed system 
according to the requirements in Sec.  63.1045(b)(3), except that Sec.  
63.1045(b)(3)(i) does not apply for the purposes of this subpart.
0
15. Section 63.7912 is amended by revising paragraph (c) to read as 
follows:

Sec.  63.7912   What are my inspection and monitoring requirements for 
separators?

* * * * *
    (c) If you use a pressurized separator that operates as a closed 
system according to Sec.  63.7910(b)(3), you must visually inspect each 
pressurized separator and closure devices for defects at least annually 
to ensure they are operating according to the design requirements in 
Sec.  63.1045(b), except that Sec.  63.1045(b)(3)(i) does not apply for 
the purposes of this subpart.
0
16. Section 63.7913 is amended by revising paragraphs (c)(1) and (d)(1) 
to read as follows:

Sec.  63.7913   How do I demonstrate continuous compliance with the 
emissions limitations and work practice standards for separators?

* * * * *
    (c) * * *
    (1) Operating and maintaining the fixed roof and its closure 
devices according to the requirements in Sec.  63.1042, except that 
Sec.  63.1042(c)(2) does not apply for the purposes of this subpart.
* * * * *
    (d) * * *
    (1) Operating the pressurized separator at all times according to 
the requirements in Sec.  63.1045, except that Sec.  63.1045(b)(3)(i) 
does not apply for the purposes of this subpart.
* * * * *
0
17. Revise the undesignated center heading for Sec. Sec.  63.7920 
through 63.7922 to read as follows:

Equipment Leaks and Pressure Relief Devices

0
18. Section 63.7920 is amended by:
0
a. Revising paragraphs (b)(1) and (2);
0
b. Adding paragraphs (b)(3) and (4);
0
c. Redesignating paragraph (d) as paragraph (f); and
0
d. Adding new paragraph (d) and paragraph (e) to read as follows:

Sec.  63.7920   What emissions limitations and work practice standards 
must I meet for equipment leaks?

* * * * *
    (b) * * *
    (1) Control equipment leaks according to all applicable 
requirements under 40 CFR part 63, subpart TT--National Emission 
Standards for Equipment Leaks--Control Level 1, with the differences 
noted in paragraphs (b)(3) and (4) of this section for the purposes of 
this subpart; or
    (2) Control equipment leaks according to all applicable 
requirements under 40 CFR part 63, subpart UU--National Emission 
Standards for Equipment Leaks--Control Level 2, with the differences 
noted in paragraphs (b)(3) of this section for the purposes of this 
subpart
    (3)(i) For the purpose of complying with the requirements of Sec.  
63.1014(b)(1) or Sec.  63.1033(b)(1), the open end is sealed when 
instrument monitoring of the open-ended valve or line conducted 
according to Method 21 of 40 CFR part 60, appendix A indicates no 
readings of 500 ppm or greater.
    (ii) For the purpose of complying with the requirements of Sec.  
63.1014(c) or Sec.  63.1033(c), open-ended valves or lines in an 
emergency shutdown system which are designed to open automatically in 
the event of a process

[[Page 46174]]

upset and that are exempt from the requirements in Sec.  63.1014(b) or 
Sec.  63.1033(b) must comply with the requirements in Sec.  
63.693(c)(2).
    (4)(i) For the purpose of complying with the requirements of Sec.  
63.1006(b)(2), the instrument reading that defines a leak is 500 parts 
per million or greater.
    (ii) For the purpose of complying with the requirements of Sec.  
63.1007(b)(2), the instrument reading that defines a leak is 5,000 
parts per million or greater for pumps handling polymerizing monomers; 
2,000 parts per million or greater for pumps in food/medical service; 
and 1,000 parts per million or greater for all other pumps.
* * * * *
    (d) For the purposes of this subpart, the requirements of Sec.  
63.7920(e) of this subpart apply rather than those of Sec.  63.1030 or 
of Sec.  63.1011, as applicable, for pressure relief devices in gas and 
vapor service. The requirements of Sec.  63.7920(e) of this subpart 
apply rather than those of Sec.  63.1029 or of Sec.  63.1010, as 
applicable, for pressure relief devices in liquid service.
    (e) Operate each pressure relief device under normal operating 
conditions, as indicated by an instrument reading of less than 500 ppm 
above the background level as detected by the method specified in Sec.  
63.1004(b) or Sec.  63.1023(b), as applicable.
* * * * *
0
19. Section 63.7923 is added before the center heading ``Closed Vent 
Systems and Control Devices'' to read as follows:

Sec.  63.7923   What emissions limitations must I meet for pressure 
relief devices?

    (a) For each pressure relief device in remediation material 
service, you must comply with either paragraph (a)(1) or (2) of this 
section following a pressure release actuation event, as applicable.
    (1) If the pressure relief device does not consist of or include a 
rupture disk, return the pressure relief device to the normal operating 
conditions specified in Sec.  63.7920(e) as soon as practicable and 
conduct instrument monitoring by the method specified in Sec.  
63.1004(b) or Sec.  63.1023(b), as applicable, no later than 5 calendar 
days after the pressure release device returns to remediation material 
service following a pressure release actuation event, except as 
provided in Sec.  63.1024(d) or of Sec.  63.1005(c), as applicable.
    (2) If the pressure relief device consists of or includes a rupture 
disk, except as provided in Sec.  63.1024(d) or of Sec.  63.1005(c), as 
applicable, install a replacement disk as soon as practicable but no 
later than 5 calendar days after the pressure release actuation event.
    (b) You must equip each pressure relief device in remediation 
material service with a device(s) or use a monitoring system sufficient 
to indicate a pressure release to the atmosphere. The device or 
monitoring system may be either specific to the pressure release device 
itself or may be associated with the process system or piping. Examples 
of these types of devices or monitoring systems include, but are not 
limited to, a rupture disk indicator, magnetic sensor, motion detector 
on the pressure relief valve stem, flow monitor, pressure monitor, or 
parametric monitoring system. The device(s) or monitoring systems must 
be capable of meeting the requirements specified in paragraphs (b)(1) 
through (3) of this section.
    (1) Identifying the pressure release;
    (2) Recording the time and duration of each pressure release; and
    (3) Notifying operators immediately that a pressure release is 
occurring.
    (c) If any pressure relief device in remediation material service 
releases directly to the atmosphere as a result of a pressure release 
actuation event, follow the requirements of paragraphs (c)(1) through 
(6) of this section.
    (1) You must calculate the quantity of HAP listed in Table 1 of 
this subpart released during each pressure release actuation event. 
Calculations may be based on data from the pressure relief device 
monitoring alone or in combination with process parameter monitoring 
data and process knowledge.
    (2) You must determine the total number of pressure release 
actuation events that occurred during the calendar year for each 
pressure relief device.
    (3) You must determine the total number of pressure release 
actuation events for each pressure relief device for which the analysis 
conducted as required by paragraph (c)(4) of this section concluded 
that the pressure release was due to a force majeure event, as defined 
in Sec.  63.7957.
    (4) You must complete an analysis to determine the source, nature 
and cause of each pressure release actuation event as soon as 
practicable, but no later than 45 days after a pressure release 
actuation event.
    (5) You must identify corrective measures to prevent future such 
pressure release actuation event s as soon as practicable, but no later 
than 45 days after a pressure release actuation event.
    (6) You must implement the corrective measure(s) identified as 
required by paragraph (c)(5) of this section within 45 days of the 
pressure release actuation event or as soon thereafter as practicable. 
For corrective measures that cannot be fully implemented within 45 days 
following the pressure release actuation event, you must record the 
corrective measure(s) completed to date, and, for measure(s) not 
already completed, a schedule for implementation, including proposed 
commencement and completion dates, no later than 45 days following the 
pressure release actuation event.
    (d) The pressure relief devices listed in paragraphs (d)(1) through 
(5) are not subject to the requirements in paragraphs (a) through (c) 
of this section.
    (1) Pressure relief devices designed and operated to route all 
pressure releases through a closed vent system to a drain system 
meeting the requirements of Sec. Sec.  63.7915-63.7918, or to a fuel 
gas system, process or control device meeting the requirements of 
Sec. Sec.  63.7925-63.7928.
    (2) Pressure relief devices in heavy liquid service, as defined in 
Sec.  63.1001 or Sec.  63.1020, as applicable.
    (3) Thermal expansion relief valves.
    (4) Pilot-operated pressure relief devices where the primary 
release valve is routed through a closed vent system to a control 
device or back into the process, to the fuel gas system, or to a drain 
system.
    (5) Balanced bellows pressure relief devices where the primary 
release valve is routed through a closed vent system to a control 
device or back into the process, to the fuel gas system, or to a drain 
system.
    (e) Except for the pressure relief devices described in paragraph 
(d) of this section, it is a violation of the requirements of 
paragraphs (b) and (c) of this section for any pressure relief device 
in remediation material service to release directly to the atmosphere 
as a result of a pressure release actuation event(s) described in 
paragraphs (e)(1) through (3) of this section.
    (1) Any pressure release actuation event for which the cause of the 
event determined as required by paragraph (c)(4) of this section was 
determined to be operator error or poor maintenance.
    (2) A second pressure release actuation event, not including force 
majeure events, from a single pressure relief device in a 3 calendar-
year period for the same cause for the same equipment.
    (3) A third pressure release actuation event, not including force 
majeure events, from a single pressure relief device in a 3 calendar-
year period for any reason.
0
20. Section 63.7925 is amended by revising paragraph (b) to read as 
follows:

[[Page 46175]]

Sec.  63.7925   What emissions limitations and work practice standards 
must I meet for closed vent systems and control devices?

* * * * *
    (b) Whenever gases or vapors containing HAP are vented through the 
closed-vent system to the control device, the control device must be 
operating.
* * * * *
0
21. Section 63.7935 is amended by:
0
a. Revising paragraphs (a) and (b);
0
b. Removing and reserving paragraph (c);
0
c. Revising paragraph (e);
0
d. Removing and reserving paragraph (f); and
0
e. Adding paragraphs (g)(4) and (5) to read as follows:

Sec.  63.7935   What are my general requirements for complying with 
this subpart?

    (a) You must be in compliance with the emissions limitations 
(including operating limits) and the work practice standards in this 
subpart at all times. The owner or operator must operate and maintain 
any affected source, including associated air pollution control 
equipment and monitoring equipment, in a manner consistent with safety 
and good air pollution control practices for minimizing emissions.
    (b) At all times, the owner or operator must operate and maintain 
any affected source, including associated air pollution control 
equipment and monitoring equipment, in a manner consistent with safety 
and good air pollution control practices for minimizing emissions. The 
general duty to minimize emissions does not require the owner or 
operator to make any further efforts to reduce emissions if levels 
required by the applicable standard have been achieved. Determination 
of whether a source is operating in compliance with operation and 
maintenance requirements will be based on information available to the 
Administrator which may include, but is not limited to, monitoring 
results, review of operation and maintenance procedures, review of 
operation and maintenance records, and inspection of the source.
* * * * *
    (e) You must report each instance in which you did not meet each 
emissions limitation and each operating limit that applies to you. You 
must also report each instance in which you did not meet the 
requirements for work practice standards that apply to you. These 
instances are deviations from the emissions limitations and work 
practice standards in this subpart. These deviations must be reported 
according to the requirements in Sec.  63.7951.
* * * * *
    (g) * * *
    (4) Continuous monitoring system (CMS) operation and maintenance 
requirements in accordance with Sec.  63.7945.
    (5) CMS data collection in accordance with Sec.  63.7946.
* * * * *
0
22. Section 63.7941 is amended by revising paragraph (b)(2) and 
paragraph (b)(4) introductory text to read as follows:

Sec.  63.7941   How do I conduct a performance test, design evaluation, 
or other type of initial compliance demonstration?

* * * * *
    (b) * * *
    (2) You must conduct performance tests under such conditions as the 
Administrator specifies based on representative performance of the 
affected source for the period being tested. Representative conditions 
exclude periods of startup and shutdown unless specified by the General 
Provisions. You may not conduct performance tests during periods of 
malfunction. You must record the process information that is necessary 
to document operating conditions during the test and include in such 
record an explanation to support that such conditions represent normal 
operation. Upon request, you must make available to the Administrator 
such records as may be necessary to determine the conditions of 
performance tests.''
* * * * *
    (4) Follow the procedures in paragraphs (b)(4)(i) through (iii) of 
this section to determine compliance with the facility-wide total 
organic mass emissions rate in Sec.  63.7890(b).
* * * * *
0
23. Section 63.7942 is revised to read as follows:

Sec.  63.7942   When must I conduct subsequent performance tests?

    For non-flare control devices, you must conduct performance tests 
at any time the EPA requires you to according to Sec.  63.7(a)(3).
0
24. Section 63.7943 is amended by revising paragraph (d) to read as 
follows:

Sec.  63.7943   How do I determine the average VOHAP concentration of 
my remediation material?

* * * * *
    (d) In the event that you and we disagree on a determination using 
knowledge of the average total VOHAP concentration for a remediation 
material, then the results from a determination of VOHAP concentration 
using direct measurement by Method 305 in 40 CFR part 60 appendix A, as 
specified in paragraph (b) of this section, will be used to determine 
compliance with the applicable requirements of this subpart. We may 
perform or require that you perform this determination using direct 
measurement.
0
25. Section 63.7944 is amended by revising paragraph (d) to read as 
follows:

Sec.  63.7944   How do I determine the maximum HAP vapor pressure of my 
remediation material?

* * * * *
    (d) In the event that you and us disagree on a determination using 
knowledge of the maximum HAP vapor pressure of the remediation 
material, then the results from a determination of maximum HAP vapor 
pressure using direct measurement by Method 25E in 40 CFR part 60 
appendix A, as specified in paragraph (b) of this section, will be used 
to determine compliance with the applicable requirements of this 
subpart. We may perform or require that you perform this determination 
using direct measurement.
0
26. Section 63.7945 is amended by adding paragraph (d) to read as 
follows:
* * * * *
    (d) Failure to meet the requirements of (a)(1) through (4) of this 
section is a deviation and must be reported according to the 
requirements in Sec.  63.7951(b)(7).
0
27. Section 63.7951 is amended by:
0
a. Adding paragraphs (a)(2)(i) and (ii);
0
b. Removing and reserving paragraph (b)(4);
0
c. Revising paragraphs (b)(7) introductory text, (b)(7)(ii), (b)(8) 
introductory text, and (b)(8)(i), (iv), and (vi),
0
d. Adding paragraphs (b)(10) and (11);
0
e. Removing and reserving paragraph (c); and
0
f. Adding paragraphs (e) through (h) to read as follows:

Sec.  63.7951   What reports must I submit and when?

    (a) * * *
    (2) * * *
    (i) For pressure relief devices in remediation material service 
subject to the requirements of Sec.  63.7923 of this subpart, you must 
submit the information listed in paragraph (a)(1)(ii) and (iii) of this 
section in the notification of compliance status required under Sec.  
63.9(h) of this part within 150 days after the first applicable

[[Page 46176]]

compliance date for pressure relief device monitoring.
    (ii) A description of the device or monitoring system to be 
implemented, including the pressure relief devices and process 
parameters to be monitored, and a description of the alarms or other 
methods by which operators will be notified of a pressure release.
* * * * *
    (b) * * *
* * * * *
    (7) For each deviation from an emissions limitation (including an 
operating limit) that occurs at an affected source for which you are 
not using a continuous monitoring system (including a CPMS or CEMS) to 
comply with an emissions limitation or work practice standard required 
in this subpart, the compliance report must contain the information 
specified in paragraphs (b)(1) through (4) and (b)(7)(i) and (ii) of 
this section..
* * * * *
    (ii) Information on the number of deviations. For each deviation, 
include the date, time, and duration, a list of the affected sources or 
equipment, an estimate of the volume of each regulated pollutant 
emitted over any emission limit, a description of the method used to 
estimate the emissions, the actions taken to minimize emissions, the 
cause of the deviation (including unknown cause), as applicable, and 
the corrective actions taken to return the affected unit to its normal 
or usual manner of operation.
    (8) For each deviation from an emissions limitation (including an 
operating limit) or work practice standard occurring at an affected 
source where you are using a continuous monitoring system (including a 
CPMS or CEMS) to comply with the emissions limitations or work practice 
standard in this subpart, you must include the information specified in 
paragraphs (b)(1) through (4) and (b)(8)(i) through (xi) of this 
section.
    (i) Information on the number of deviations. For each deviation, 
include the date, time, and duration, a list of the affected sources or 
equipment, an estimate of the volume of each regulated pollutant 
emitted over any emission limit, a description of the method used to 
estimate the emissions, the actions taken to minimize emissions, the 
cause of the deviation (including unknown cause), as applicable, and 
the corrective actions taken to return the affected unit to its normal 
or usual manner of operation.
* * * * *
    (iv) For each deviation caused when the daily average value of a 
monitored operating parameter is less than the minimum operating 
parameter limit (or, if applicable, greater than the maximum operating 
parameter limit), the report must include the daily average values of 
the monitored parameter, the applicable operating parameter limit, and 
the date and duration of the period that the deviation occurred. For 
each deviation caused by lack of monitoring data, the report must 
include the date and duration of period when the monitoring data were 
not collected and the reason why the data were not collected.
* * * * *
    (vi) A breakdown of the total duration of the deviations during the 
reporting period into those that are due to control equipment problems, 
process problems, other known causes, and unknown causes.
* * * * *
    (10) For pressure relief devices in remediation material service, 
compliance reports must include the information specified in paragraphs 
(b)(10)(i) through (iii) of this section.
    (i) For pressure relief devices in remediation material service 
subject to Sec.  63.7920(e) of this subpart, report any instrument 
reading of 500 ppm above the background level or greater, if detected 
more than 5 days after a pressure release.
    (ii) For pressure relief devices in remediation service subject to 
Sec.  63.7923(a), report confirmation that any monitoring required to 
be done during the reporting period to show compliance was conducted.
    (iii) For pressure relief devices in remediation material service 
subject to Sec.  63.7923(c) of this subpart, report each pressure 
release to the atmosphere, including the following information:
    (A) The date, time, and duration of the pressure release actuation 
event.
    (B) An estimate of the mass quantity of each HAP listed in Table 1 
of this subpart emitted during the pressure release actuation event and 
the method used for determining this quantity.
    (C) The source, nature and cause of the pressure release actuation 
event.
    (D) The actions taken to prevent this pressure release actuation 
event.
    (E) The measures implemented during the reporting period to prevent 
future such pressure release actuation events, and, if applicable, the 
implementation schedule for planned corrective actions to be 
implemented subsequent to the reporting period.
    (11) Pressure tank closure device or bypass deviation information. 
Compliance reports must include the information specified in paragraph 
(b)(11)(iv) of this section when any of the conditions in paragraphs 
(b)(11)(i) through (iii) of this section are met.
    (i) Any pressure tank closure device, as specified in specified in 
Sec.  63.7895(d)(4) of this subpart and Sec.  63.685(h)(2) of this 
subpart, has released to the atmosphere.
    (ii) Any closed vent system that includes bypass devices that could 
divert a vent a stream away from the control device and into the 
atmosphere, as specified in Sec.  63.7927(a)(2) of this subpart, has 
released directly to the atmosphere.
    (iii) Any open-ended valve or line in an emergency shutdown system 
which is designed to open automatically in the event of a process 
upset, as specified in Sec.  63.1014(c) or Sec.  63.1033(c), has 
released directly to the atmosphere.
    (iv) The compliance report must include the information specified 
in paragraphs (b)(11)(iv)(A) through (E) of this section.
    (A) The source, nature and cause of the release.
    (B) The date, time and duration of the discharge.
    (C) An estimate of the quantity of HAP listed in Table 1 of this 
subpart emitted during the release and the method used for determining 
this quantity.
    (D) The actions taken to prevent this release.
    (E) The measures adopted to prevent future such releases.
* * * * *
    (e) Performance test and CMS performance evaluation reports. Within 
60 days after the date of completing each performance test or 
continuous monitoring system (CMS) performance evaluation (as defined 
in Sec.  63.2) required by this subpart, the owner or operator must 
submit the results of the performance test or performance evaluation 
according to the manner specified by either paragraph (e)(1) or (2) of 
this section.
    (1) Data collected using test methods supported by the EPA's 
Electronic Reporting Tool (ERT) as listed on the EPA's ERT website 
(https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert) at the time of the test. Submit the results of the 
performance test or the performance evaluation of CMS measuring 
relative accuracy test audit (RATA) pollutants to the EPA via the 
Compliance and Emissions Data Reporting Interface (CEDRI), which can be 
accessed through the EPA's Central Data Exchange (CDX) (https://cdx.epa.gov/). The data must be submitted in a file format generated 
through the use of the EPA's ERT.

[[Page 46177]]

Alternatively, you may submit an electronic file consistent with the 
extensible markup language (XML) schema listed on the EPA's ERT 
website.
    (2) Data collected using test methods that are not supported by the 
EPA's ERT as listed on the EPA's ERT website at the time of the test. 
The results of the performance test or the performance evaluation of 
CMS measuring relative accuracy test audit (RATA) pollutants by methods 
that are not supported by the ERT must be included as an attachment in 
the ERT or an alternate electronic file consistent with the XML schema 
listed on the EPA's ERT website. Submit the ERT generated package or 
alternative file to the EPA via CEDRI.
    (f) Submitting reports electronically. If you are required to 
submit reports following the procedure specified in this paragraph, you 
must submit reports to the EPA via CEDRI, which can be accessed through 
the EPA's Central Data Exchange (CDX) (https://cdx.epa.gov/). You must 
use the appropriate electronic report template on the CEDRI website 
(https://www.epa.gov/electronic-reporting-air-emissions/compliance-and-emissions-data-reporting-interface-cedri) for this subpart. The report 
must be submitted by the deadline specified in this subpart, regardless 
of the method in which the report is submitted. If you claim some of 
the information required to be submitted via CEDRI is confidential 
business information (CBI), submit a complete report, including 
information claimed to be CBI, to the EPA. The report must be generated 
using the appropriate form on the CEDRI website. Submit the file on a 
compact disc, flash drive, or other commonly used electronic storage 
medium and clearly mark the medium as CBI. Mail the electronic medium 
to U.S. EPA/OAQPS/CORE CBI Office, Attention: Group Leader, Measurement 
Policy Group, MD C404-02, 4930 Old Page Rd., Durham, NC 27703. The same 
file with the CBI omitted must be submitted to the EPA via the EPA's 
CDX as described earlier in this paragraph.
    (g) Claims of EPA system outage. If you are required to 
electronically submit a report through CEDRI in the EPA's CDX, you may 
assert a claim of EPA system outage for failure to timely comply with 
the reporting requirement. To assert a claim of EPA system outage, you 
must meet the requirements outlined in paragraphs (g)(1) through (7) of 
this section.
    (1) You must have been or will be precluded from accessing CEDRI 
and submitting a required report within the time prescribed due to an 
outage of either the EPA's CEDRI or CDX systems.
    (2) The outage must have occurred within the period of time 
beginning five business days prior to the date that the submission is 
due.
    (3) The outage may be planned or unplanned.
    (4) You must submit notification to the Administrator in writing as 
soon as possible following the date you first knew, or through due 
diligence should have known, that the event may cause or has caused a 
delay in reporting.
    (5) You must provide to the Administrator a written description 
identifying:
    (i) The date(s) and time(s) when CDX or CEDRI was accessed and the 
system was unavailable;
    (ii) A rationale for attributing the delay in reporting beyond the 
regulatory deadline to EPA system outage;
    (iii) Measures taken or to be taken to minimize the delay in 
reporting; and
    (iv) The date by which you propose to report, or if you have 
already met the reporting requirement at the time of the notification, 
the date you reported.
    (6) The decision to accept the claim of EPA system outage and allow 
an extension to the reporting deadline is solely within the discretion 
of the Administrator.
    (7) In any circumstance, the report must be submitted 
electronically as soon as possible after the outage is resolved.
    (h) Claims of force majeure. If you are required to electronically 
submit a report through CEDRI in the EPA's CDX, you may assert a claim 
of force majeure for failure to timely comply with the reporting 
requirement. To assert a claim of force majeure, you must meet the 
requirements outlined in paragraphs (h)(1) through (5) of this section.
    (1) You may submit a claim if a force majeure event is about to 
occur, occurs, or has occurred or there are lingering effects from such 
an event within the period of time beginning five business days prior 
to the date the submission is due. For the purposes of this section, a 
force majeure event is defined as an event that will be or has been 
caused by circumstances beyond the control of the affected facility, 
its contractors, or any entity controlled by the affected facility that 
prevents you from complying with the requirement to submit a report 
electronically within the time period prescribed. Examples of such 
events are acts of nature (e.g., hurricanes, earthquakes, or floods), 
acts of war or terrorism, or equipment failure or safety hazard beyond 
the control of the affected facility (e.g., large scale power outage).
    (2) You must submit notification to the Administrator in writing as 
soon as possible following the date you first knew, or through due 
diligence should have known, that the event may cause or has caused a 
delay in reporting.
    (3) You must provide to the Administrator:
    (i) A written description of the force majeure event;
    (ii) A rationale for attributing the delay in reporting beyond the 
regulatory deadline to the force majeure event;
    (iii) Measures taken or to be taken to minimize the delay in 
reporting; and
    (iv) The date by which you propose to report, or if you have 
already met the reporting requirement at the time of the notification, 
the date you reported.
    (4) The decision to accept the claim of force majeure and allow an 
extension to the reporting deadline is solely within the discretion of 
the Administrator.
    (5) In any circumstance, the reporting must occur as soon as 
possible after the force majeure event occurs.
0
28. Section 63.7952 is amended by revising paragraph (a)(2) and adding 
paragraph (e) to read as follows:

Sec.  63.7952   What records must I keep?

    (a) * * *
    (2) The records in Sec.  63.6(e)(3)(iii) through (v) related to 
startups, shutdowns, and malfunctions.
    (i) For each deviation from an emissions limitation (including an 
operating limit) or work practice standard occurring at an affected 
source, you must record information on the number of deviations. For 
each deviation, include the date, time, and duration, a list of the 
affected sources or equipment, an estimate of the volume of each 
regulated pollutant emitted over any emission limit, a description of 
the method used to estimate the emissions, the actions taken to 
minimize emissions, the cause of the deviation (including unknown 
cause), as applicable, and the corrective actions taken to return the 
affected unit to its normal or usual manner of operation.
    (ii) For pressure relief devices in remediation material service, 
keep records of the information specified in paragraphs (a)(2)(ii)(A) 
through (C) of this section, as applicable.
    (A) A list of identification numbers for pressure relief devices 
that are not subject to the requirements of Sec.  63.7923(a) through 
(c) under the provisions of Sec.  63.7923(d).
    (B) A list of identification numbers for pressure relief devices 
subject to the requirements of Sec.  63.7923(a) through (c) that do not 
consist of or include a rupture disk.

[[Page 46178]]

    (C) A list of identification numbers for pressure relief devices 
subject to the requirements of Sec.  63.7923(a) through (c) equipped 
with rupture disks.
    (iii) For pressure relief devices in remediation material service 
subject to Sec.  63.7923(c) of this subpart, keep records of each 
pressure release event to the atmosphere as specified in paragraphs 
(a)(2)(iii)(A) through (I) of this section.
    (A) The date, time, and duration of the pressure release event.
    (B) The dates and results of the EPA Method 21 of 40 CFR part 60, 
appendix A, monitoring following a pressure release event, if 
applicable. The results of each monitoring event shall include the 
measured background level and the maximum instrument reading measured 
at each pressure relief device.
    (C) The dates replacement rupture disks were installed following a 
pressure release event, if applicable.
    (D) An estimate of the mass quantity of each HAP listed in Table 1 
of this subpart emitted during the pressure release event and the 
method used for determining this quantity.
    (E) The source, nature and cause of the pressure release event, 
including an identification of the affected pressure relief device(s) 
and a statement noting whether the event resulted from the same 
cause(s) identified following a previous pressure release event.
    (F) The corrective measures identified to prevent future such 
pressure release events, or an explanation of why corrective measures 
are not necessary.
    (G) The actions taken to prevent this pressure release event.
    (H) Records of the corrective measures implemented, including a 
description of the corrective measure(s) completed within the first 45 
days following a pressure release event, and, if applicable, the 
implementation schedule for planned corrective measures to be 
implemented subsequent to the first 45 days following the pressure 
release event, including proposed commencement and completion dates.
    (I) Records of the number of pressure release events during each 
calendar year and the number of those events for which the cause was 
determined to be a force majeure event. Keep these records for the 
current calendar year and the past five calendar years.
    (iv)(A) For pressure tank closure devices, as specified in Sec.  
63.7895(d)(4) and Sec.  63.685(h)(2), keep records of each release to 
the atmosphere, including the information specified in paragraphs 
(C)(1) though (7) of this section.
    (B) For each closed vent system that includes bypass devices that 
could divert a stream away from the control device and into the 
atmosphere, as specified in Sec.  63.7927(a)(2), and each open-ended 
valve or line in an emergency shutdown system which is designed to open 
automatically in the event of a process upset, as specified in Sec.  
63.1014(c) or Sec.  63.1033(c), keep records of each release to the 
atmosphere, including the information specified in paragraphs (C)(1) 
though (7) of this section.
    (C)(1) The source, nature, and cause of the release.
    (2) The date, time, and duration of the release.
    (3) An estimate of the quantity of HAP listed in Table 1 of this 
subpart emitted during the release and the calculations used for 
determining this quantity.
    (4) The actions taken to prevent this release.
    (5) The measures adopted to prevent future such release.
    (6) Hourly records of whether the bypass flow indicator specified 
under Sec.  63.7927(a)(2)(i) was operating and whether a diversion was 
detected at any time during the hour, as well as records of the times 
of all periods when the vent stream is diverted from the control device 
or the flow indicator is not operating.
    (7) Where a seal mechanism is used to comply with Sec.  
63.7927(a)(2)(ii), hourly records of flow are not required. In such 
cases, you must record that the monthly visual inspection of the seals 
or closure mechanism has been done and record the duration of all 
periods when the seal mechanism is broken, the bypass line valve 
position has changed, or the key for a lock-and-key type lock has been 
checked out, and records of any car-seal that has broken.
* * * * *
    (e) Any records required to be maintained by this part that are 
submitted electronically via the EPA's CEDRI may be maintained in 
electronic format. This ability to maintain electronic copies does not 
affect the requirement for facilities to make records, data, and 
reports available upon request to a delegated air agency or the EPA as 
part of an on-site compliance evaluation.
0
29. Section 63.7957 is amended by:
0
a. Adding, in alphabetical order, a definition for ``Bypass;''
0
b. Revising the definition of ``Deviation;''
0
c. Adding, in alphabetical order, definitions for ``Force majeure,'' 
``Pressure release,'' and ``Pressure relief device or valve;''
0
d. Revising the definition of ``Process vent;'' and
0
e. Removing the definition of ``Safety device.''
    The additions and revisions read as follows:

Sec.  63.7957   What definitions apply to this subpart?

* * * * *
    Bypass means diverting a process vent or closed vent system stream 
to the atmosphere such that it does not first pass through an emission 
control device.
* * * * *
    Deviation means any instance in which an affected source subject to 
this subpart, or an owner or operator of such a source:
    (1) Fails to meet any requirement or obligation established by this 
subpart, including but not limited to any emissions limitation 
(including any operating limit), or work practice standard;
    (2) Fails to meet any term or condition that is adopted to 
implement an applicable requirement in this subpart and that is 
included in the operating permit for any affected source required to 
obtain such a permit; or
    (3) Fails to meet any emissions limitation, (including any 
operating limit), or work practice standard in this subpart regardless 
of whether or not such failure is permitted by this subpart.
* * * * *
    Force majeure event means a release of HAP directly to the 
atmosphere from a pressure relief device that is demonstrated to the 
satisfaction of the Administrator to result from an event beyond the 
owner or operator's control, such as natural disasters; acts of war or 
terrorism; loss of a utility external to the ethylene production unit 
(e.g., external power curtailment), excluding power curtailment due to 
an interruptible service agreement; and fire or explosion originating 
at a near or adjoining facility outside of the site remediation 
affected source that impacts the site remediation affected source's 
ability to operate.
* * * * *
    Pressure release means the emission of materials resulting from the 
system pressure being greater than the set pressure of the pressure 
relief device. This release can be one release or a series of releases 
over a short time period.
    Pressure relief device or valve means a safety device used to 
prevent operating pressures from exceeding the maximum allowable 
working pressure of the process equipment. A common pressure relief 
device is a spring-loaded pressure relief valve. Devices that are 
actuated either by a pressure of less than

[[Page 46179]]

or equal to 2.5 pounds per square inch gauge or by a vacuum are not 
pressure relief devices.
* * * * *
    Process vent means any open-ended pipe, stack, duct, or other 
opening intended to allow the passage of gases, vapors, or fumes to the 
atmosphere and this passage is caused by mechanical means (such as 
compressors, vacuum-producing systems or fans) or by process-related 
means (such as volatilization produced by heating). For the purposes of 
this subpart, a process vent is neither a pressure relief device (as 
defined in this section) nor a stack, duct or other opening used to 
exhaust combustion products from a boiler, furnace, heater, 
incinerator, or other combustion device.
* * * * *
0
30. Table 3 to subpart GGGGG of part 63 is revised to read as follows:
    As stated in Sec.  63.7940, you must comply with the applicable 
General Provisions requirements according to the following table:

            Table 3 to Subpart GGGGG of Part 63--Applicability of General Provisions to Subpart GGGGG
----------------------------------------------------------------------------------------------------------------
             Citation                     Subject              Brief description       Applies to subpart GGGGG
----------------------------------------------------------------------------------------------------------------
Sec.   63.1......................  Applicability........  Initial Applicability       Yes.
                                                           Determination;
                                                           Applicability After
                                                           Standard Established;
                                                           Permit Requirements;
                                                           Extensions, Notifications.
Sec.   63.2......................  Definitions..........  Definitions for part 63     Yes.
                                                           standards.
Sec.   63.3......................  Units and              Units and abbreviations     Yes.
                                    Abbreviations.         for part 63 standards.
Sec.   63.4......................  Prohibited Activities  Prohibited Activities;      Yes.
                                                           Compliance date;
                                                           Circumvention,
                                                           Severability.
Sec.   63.5......................  Construction/          Applicability;              Yes.
                                    Reconstruction.        applications; approvals.
Sec.   63.6(a)...................  Applicability........  General Provisions (GP)     Yes.
                                                           apply unless compliance
                                                           extension GP apply to
                                                           area sources that become
                                                           major.
Sec.   63.6(b)(1)-(4)............  Compliance Dates for   Standards apply at          Yes.
                                    New and                effective date; 3 years
                                    Reconstructed          after effective date;
                                    sources.               upon startup; 10 years
                                                           after construction or
                                                           reconstruction commences
                                                           for 112(f).
Sec.   63.6(b)(5)................  Notification.........  Must notify if commenced    Yes.
                                                           construction or
                                                           reconstruction after
                                                           proposal.
Sec.   63.6(b)(6)................  [Reserved]...........
Sec.   63.6(b)(7)................  Compliance Dates for   Area sources that become    Yes.
                                    New and                major must comply with
                                    Reconstructed Area     major source standards
                                    Sources That Become    immediately upon becoming
                                    Major.                 major, regardless of
                                                           whether required to
                                                           comply when they were an
                                                           area source.
Sec.   63.6(c)(1)-(2)............  Compliance Dates for   Comply according to date    Yes.
                                    Existing Sources.      in subpart, which must be
                                                           no later than 3 years
                                                           after effective date. For
                                                           112(f) standards, comply
                                                           within 90 days of
                                                           effective date unless
                                                           compliance extension.
Sec.   63.6(c)(3)-(4)............  [Reserved]...........
Sec.   63.6(c)(5)................  Compliance Dates for   Area sources that become    Yes.
                                    Existing Area          major must comply with
                                    Sources That Become    major source standards by
                                    Major.                 date indicated in subpart
                                                           or by equivalent time
                                                           period (for example, 3
                                                           years).
Sec.   63.6(d)...................  [Reserved]...........
Sec.   63.6(e)(1)-(2)............  Operation &            ..........................  No, see Sec.   63.7935(b).
                                    Maintenance.
Sec.   63.6(e)(3)................  Startup, Shutdown,     ..........................  No.
                                    and Malfunction Plan
                                    (SSMP).
Sec.   63.6(f)(1)................  Compliance Except      ..........................  No, see Sec.   63.7935(b).
                                    During SSM.
Sec.   63.6(f)(2)-(3)............  Methods for            Compliance based on         Yes.
                                    Determining            performance test,
                                    Compliance.            operation and maintenance
                                                           plans, records,
                                                           inspection.
Sec.   63.6(g)(1)-(3)............  Alternative Standard.  Procedures for getting an   Yes.
                                                           alternative standard.
Sec.   63.6(h)...................  Opacity/Visible        Requirements for opacity    No. No opacity standards.
                                    Emissions (VE)         and visible emissions
                                    Standards.             limits.
Sec.   63.6(i)(1)-(14)...........  Compliance Extension.  Procedures and criteria     Yes.
                                                           for Administrator to
                                                           grant compliance
                                                           extension.
Sec.   63.6(j)...................  Presidential           President may exempt        Yes.
                                    Compliance Exemption.  source category from
                                                           requirement to comply
                                                           with final rule.
Sec.   63.7(a)(1)-(2)............  Performance Test       Dates for Conducting        Yes.
                                    Dates.                 Initial Performance
                                                           Testing and Other
                                                           Compliance
                                                           Demonstrations. Must
                                                           conduct 180 days after
                                                           first subject to final
                                                           rule.
Sec.   63.7(a)(3)................  CAA Section 114        Administrator may require   Yes.
                                    Authority.             a performance test under
                                                           CAA section 114 at any
                                                           time.
Sec.   63.7(b)(1)................  Notification of        Must notify Administrator   Yes.
                                    Performance Test.      60 days before the test.
Sec.   63.7(b)(2)................  Notification of        If rescheduling a           Yes.
                                    Rescheduling.          performance test is
                                                           necessary, must notify
                                                           Administrator 5 days
                                                           before scheduled date of
                                                           rescheduled date.
Sec.   63.7(c)...................  Quality Assurance/     Requirement to submit site- Yes.
                                    Test Plan.             specific test plan 60
                                                           days before the test or
                                                           on date Administrator
                                                           agrees with: Test plan
                                                           approval procedures;
                                                           performance audit
                                                           requirements; internal
                                                           and external QA
                                                           procedures for testing.
Sec.   63.7(d)...................  Testing Facilities...  Requirements for testing    Yes.
                                                           facilities.

[[Page 46180]]

 
Sec.   63.7(e)(1)................  Conditions for         Performance tests must be   No. You may not conduct
                                    Conducting             conducted under             performance tests during
                                    Performance Tests.     representative              periods of malfunction.
                                                           conditions. Cannot          You must record the
                                                           conduct performance tests   process information that
                                                           during SSM. Not a           is necessary to document
                                                           violation to exceed         operating conditions
                                                           standard during SSM.        during the test and
                                                                                       include in such record an
                                                                                       explanation to support
                                                                                       that such conditions
                                                                                       represent normal
                                                                                       operation. Upon request,
                                                                                       you must make available
                                                                                       to the Administrator such
                                                                                       records as may be
                                                                                       necessary to determine
                                                                                       the conditions of
                                                                                       performance tests.
Sec.   63.7(e)(2)................  Conditions for         Must conduct according to   Yes.
                                    Conducting             rule and EPA test methods
                                    Performance Tests.     unless Administrator
                                                           approves alternative.
Sec.   63.7(e)(3)................  Test Run Duration....  Must have three test runs   Yes.
                                                           of at least one hour
                                                           each. Compliance is based
                                                           on arithmetic mean of
                                                           three runs. Conditions
                                                           when data from an
                                                           additional test run can
                                                           be used.
Sec.   63.7(f)...................  Alternative Test       Procedures by which         Yes.
                                    Method.                Administrator can grant
                                                           approval to use an
                                                           alternative test method.
Sec.   63.7(g)...................  Performance Test Data  Must include raw data in    Yes.
                                    Analysis.              performance test report.
                                                           Must submit performance
                                                           test data 60 days after
                                                           end of test with the
                                                           Notification of
                                                           Compliance Status. Keep
                                                           data for 5 years.
Sec.   63.7(h)...................  Waiver of Tests......  Procedures for              Yes.
                                                           Administrator to waive
                                                           performance test.
Sec.   63.8(a)(1)................  Applicability of       Subject to all monitoring   Yes.
                                    Monitoring             requirements in standard.
                                    Requirements.
Sec.   63.8(a)(2)................  Performance            Performance Specifications  Yes.
                                    Specifications.        in appendix B of part 60
                                                           apply.
Sec.   63.8(a)(3)................  [Reserved]...........
Sec.   63.8(a)(4)................  Monitoring with        Unless your rule says       Yes.
                                    Flares.                otherwise, the
                                                           requirements for flares
                                                           in 63.11 apply.
Sec.   63.8(b)(1)................  Monitoring...........  Must conduct monitoring     Yes.
                                                           according to standard
                                                           unless Administrator
                                                           approves alternative.
Sec.   63.8(b)(2)-(3)............  Multiple Effluents     Specific requirements for   Yes.
                                    and Multiple           installing monitoring
                                    Monitoring Systems.    systems. Must install on
                                                           each effluent before it
                                                           is combined and before it
                                                           is released to the
                                                           atmosphere unless
                                                           Administrator approves
                                                           otherwise. If more than
                                                           one monitoring system on
                                                           an emissions point, must
                                                           report all monitoring
                                                           system results, unless
                                                           one monitoring system is
                                                           a backup.
Sec.   63.8(c)(1)................  Monitoring System      Maintain monitoring system  Yes.
                                    Operation and          in a manner consistent
                                    Maintenance.           with good air pollution
                                                           control practices.
Sec.   63.8(c)(1)(i).............  Monitoring System      Operate and maintain        No.
                                    Operation.             system as specified in
                                                           Sec.   63.6(e)(1).
Sec.   63.8(c)(1)(ii)............  Monitoring System      Keep part for routine       Yes.
                                    Repair.                repairs available.
Sec.   63.8(c)(1)(iii)...........  Monitoring System SSM  Develop an SSM Plan for     No.
                                    Plan.                  the monitoring system.
Sec.   63.8(c)(2)-(3)............  Monitoring System      Must install to get         Yes.
                                    Installation.          representative emissions
                                                           and parameter
                                                           measurements. Must verify
                                                           operational status before
                                                           or at performance test.
Sec.   63.8(c)(4)................  Continuous Monitoring  CMS must be operating       No.
                                    System (CMS)           except during breakdown,
                                    Requirements.          out-of-control, repair,
                                                           maintenance, and high-
                                                           level calibration drifts.
Sec.   63.8(c)(4)(i)-(ii)........  Continuous Monitoring  COMS must have a minimum    Yes. However, COMS are not
                                    System (CMS)           of one cycle of sampling    applicable. Requirements
                                    Requirements.          and analysis for each       for CPMS are listed in
                                                           successive 10-second        Sec.  Sec.   63.7900 and
                                                           period and one cycle of     63.7913.
                                                           data recording for each
                                                           successive 6-minute
                                                           period. CEMS must have a
                                                           minimum of one cycle of
                                                           operation for each
                                                           successive 15-minute
                                                           period.
Sec.   63.8(c)(5)................  COMS Minimum           COMS minimum procedures...  No.
                                    Procedures.
Sec.   63.8(c)(6)................  CMS Requirements.....  Zero and High level         Yes. However requirements
                                                           calibration check           for CPMS are addressed in
                                                           requirements.               Sec.   63.7927.
Sec.   63.8(c)(7)-(8)............  CMS Requirements.....  Out-of-control periods,     Yes.
                                                           including reporting.
Sec.   63.8(d)...................  CMS Quality Control..  Requirements for CMS        Yes.
                                                           quality control,
                                                           including calibration,
                                                           etc. Must keep quality
                                                           control plan on record
                                                           for 5 years. Keep old
                                                           versions for 5 years
                                                           after revisions.
Sec.   63.8(e)...................  CMS Performance        Notification, performance   Yes.
                                    Evaluation.            evaluation test plan,
                                                           reports.
Sec.   63.8(f)(1)-(5)............  Alternative            Procedures for              Yes.
                                    Monitoring Method.     Administrator to approve
                                                           alternative monitoring.
Sec.   63.8(f)(6)................  Alternative to         Procedures for              No.
                                    Relative Accuracy      Administrator to approve
                                    Test.                  alternative relative
                                                           accuracy tests for CEMS.
Sec.   63.8(g)(1)-(4)............  Data Reduction.......  COMS 6-minute averages      Yes. However, COMS are not
                                                           calculated over at least    applicable. Requirements
                                                           36 evenly spaced data       for CPMS are addressed in
                                                           points. CEMS 1-hour         Sec.  Sec.   63.7900 and
                                                           averages computed over at   63.7913.
                                                           least four equally spaced
                                                           data points.
Sec.   63.8(g)(5)................  Data Reduction.......  Data that cannot be used    No.
                                                           in computing averages for
                                                           CEMS and COMS.
Sec.   63.9(a)...................  Notification           Applicability and State     Yes.
                                    Requirements.          Delegation.

[[Page 46181]]

 
Sec.   63.9(b)(1)-(5)............  Initial Notifications  Submit notification 120     Yes.
                                                           days after effective
                                                           date. Notification of
                                                           intent to construct/
                                                           reconstruct; Notification
                                                           of commencement of
                                                           construct/reconstruct;
                                                           Notification of startup.
                                                           Contents of each.
Sec.   63.9(c)...................  Request for            Can request if cannot       Yes.
                                    Compliance Extension.  comply by date or if
                                                           installed BACT/LAER.
Sec.   63.9(d)...................  Notification of        For sources that commence   Yes.
                                    Special Compliance     construction between
                                    Requirements for New   proposal and promulgation
                                    Source.                and want to comply 3
                                                           years after effective
                                                           date.
Sec.   63.9(e)...................  Notification of        Notify Administrator 60     Yes.
                                    Performance Test.      days prior.
Sec.   63.9(f)...................  Notification of VE/    Notify Administrator 30     No.
                                    Opacity Test.          days prior.
Sec.   63.9(g)...................  Additional             Notification of             Yes. However, there are no
                                    Notifications When     performance evaluation.     opacity standards.
                                    Using CMS.             Notification using COMS
                                                           data. Notification that
                                                           exceeded criterion for
                                                           relative accuracy.
Sec.   63.9(h)(1)-(6)............  Notification of        Contents. Due 60 days       Yes.
                                    Compliance Status.     after end of performance
                                                           test or other compliance
                                                           demonstration, except for
                                                           opacity/VE, which are due
                                                           30 days after. When to
                                                           submit to Federal vs.
                                                           State authority.
Sec.   63.9(i)...................  Adjustment of          Procedures for              Yes.
                                    Submittal Deadlines.   Administrator to approve
                                                           change in when
                                                           notifications must be
                                                           submitted.
Sec.   63.9(j)...................  Change in Previous     Must submit within 15 days  Yes.
                                    Information.           after the change.
Sec.   63.10(a)..................  Recordkeeping/         Applies to all, unless      Yes.
                                    Reporting.             compliance extension.
                                                           When to submit to Federal
                                                           vs. State authority.
                                                           Procedures for owners of
                                                           more than 1 source.
Sec.   63.10(b)(1)...............  Recordkeeping/         General Requirements. Keep  Yes.
                                    Reporting.             all records readily
                                                           available. Keep for 5
                                                           years.
Sec.   63.10(b)(2)(i) and (ii)...  Records related to     Exceedance of emission      No.
                                    SSM.                   limit during startup,
                                                           shutdown or malfunction.
Sec.   63.10(b)(2)(iii)..........  Maintenance Records..  Maintenance on air          Yes.
                                                           pollution control
                                                           equipment..
Sec.   63.10(b)(2)(iv) and (v)...  Records related to     Actions during SSM........  No.
                                    SSM.
Sec.   63.10(b)(2)(vi) and (x-xi)  CMS Records..........  Malfunctions, inoperative,  Yes.
                                                           out-of-control.
                                                           Calibration checks.
                                                           Adjustments, maintenance.
Sec.   63.10(b)(2)(vii)-(ix).....  Records..............  Measurements to             Yes.
                                                           demonstrate compliance
                                                           with emissions
                                                           limitations. Performance
                                                           test, performance
                                                           evaluation, and visible
                                                           emissions observation
                                                           results. Measurements to
                                                           determine conditions of
                                                           performance tests and
                                                           performance evaluations.
Sec.   63.10(b)(2)(xii)..........  Records..............  Records when under waiver.  Yes.
Sec.   63.10(b)(2)(xiii).........  Records..............  Records when using          No.
                                                           alternative to relative
                                                           accuracy test.
Sec.   63.10(b)(2)(xiv)..........  Records..............  All documentation           Yes.
                                                           supporting Initial
                                                           Notification and
                                                           Notification of
                                                           Compliance Status.
Sec.   63.10(b)(3)...............  Records..............  Applicability               Yes.
                                                           Determinations.
Sec.   63.10(c)..................  Records..............  Additional Records for CMS  No.
Sec.   63.10(d)(1)...............  General Reporting      Requirement to report.....  Yes.
                                    Requirements.
Sec.   63.10(d)(2)...............  Report of Performance  When to submit to Federal   Yes.
                                    Test Results.          or State authority.
Sec.   63.10(d)(3)...............  Reporting Opacity or   What to report and when...  No.
                                    VE Observations.
Sec.   63.10(d)(4)...............  Progress Reports.....  Must submit progress        Yes.
                                                           reports on schedule if
                                                           under compliance
                                                           extension.
Sec.   63.10(d)(5)...............  Startup, Shutdown,     Contents and submission...  No.
                                    and Malfunction
                                    Reports.
Sec.   63.10(e)(1)-(2)...........  Additional CMS         Must report results for     Yes. However, COMS are not
                                    Reports.               each CEM on a unit          applicable.
                                                           Written copy of
                                                           performance evaluation
                                                           Three copies of COMS
                                                           performance evaluation.
Sec.   63.10(e)(3)...............  Reports..............  Excess Emissions Reports..  No.
Sec.   63.10(e)(3)(i-iii)........  Reports..............  Schedule for reporting      No.
                                                           excess emissions and
                                                           parameter monitor
                                                           exceedance (now defined
                                                           as deviations).
Sec.   63.10(e)(3)(iv-v).........  Excess Emissions       Requirement to revert to    No.
                                    Reports.               quarterly submission if
                                                           there is an excess
                                                           emissions and parameter
                                                           monitor exceedance (now
                                                           defined as deviations).
                                                           Provision to request
                                                           semiannual reporting
                                                           after compliance for one
                                                           year. Submit report by
                                                           30th day following end of
                                                           quarter or calendar half.
                                                           If there has not been an
                                                           exceedance or excess
                                                           emissions (now defined as
                                                           deviations), report
                                                           contents is a statement
                                                           that there have been no
                                                           deviations.
Sec.   63.10(e)(3)(iv-v).........  Excess Emissions       Must submit report          No.
                                    Reports.               containing all of the
                                                           information in Sec.  Sec.
                                                             63.10(c)(5-13) and
                                                           63.8(c)(7-8).
Sec.   63.10(e)(3)(vi-viii)......  Excess Emissions       Requirements for reporting  No.
                                    Report and Summary     excess emissions for CMSs
                                    Report.                (now called deviations).
                                                           Requires all of the
                                                           information in Sec.  Sec.
                                                             63.10(c)(5-13) and
                                                           63.8(c)(7-8).
Sec.   63.10(e)(4)...............  Reporting COMS data..  Must submit COMS data with  No.
                                                           performance test data.

[[Page 46182]]

 
Sec.   63.10(f)..................  Waiver for             Procedures for              Yes.
                                    Recordkeeping/         Administrator to waive.
                                    Reporting.
Sec.   63.11.....................  Control and work       Requirements for flares     Yes.
                                    practice               and alternative work
                                    requirements.          practice for equipment
                                                           leaks.
Sec.   63.12.....................  Delegation...........  State authority to enforce  Yes.
                                                           standards.
Sec.   63.13.....................  Addresses............  Addresses where reports,    Yes.
                                                           notifications, and
                                                           requests are sent.
Sec.   63.14.....................  Incorporation by       Test methods incorporated   Yes.
                                    Reference.             by reference.
Sec.   63.15.....................  Availability of        Public and confidential     Yes.
                                    Information.           information.
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[FR Doc. 2019-17223 Filed 8-30-19; 8:45 am]
 BILLING CODE 6560-50-P