National Emission Standards for Hazardous Air 

Pollutant Emissions: Off-Site Waste and Recovery 

Operations

Summary of Public Comments and Responses on Proposed Rule 

(79 FR 37850, July 2, 2014)

U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Sector Policies and Programs Division

Research Triangle Park, NC 27711
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TABLE OF CONTENTS

1.0 Introduction..........................................................................................................................1

2.0 Risk-Related Assessment and Standards.............................................................................3

2.1 Risk Assessment Data and Methodology ......................................................................3

2.2 Consideration of Risks from Entire Facilities, Industrial Clusters, and Other Sources 

in Risk Assessment ......................................................................................................12

2.3 Consideration of Demographics in Risk Assessment ..................................................14

2.4 Additional Standards to Address Risks........................................................................15

3.0 Startup, Shutdown, and Malfunction Exemption...............................................................18

4.0 Electronic Reporting Requirements...................................................................................24

5.0 Equipment Leak Provisions...............................................................................................26

5.1 Open Ended Line Provisions .......................................................................................26

5.2 Pressure Relief Device Provisions...............................................................................27

5.3 Compliance with 40 CFR Part 63 Subpart H, Including Connector Monitoring 

Provisions.....................................................................................................................29

6.0 Tank Provisions .................................................................................................................30

7.0 Control Device, Performance Testing, and Monitoring Provisions...................................30

8.0 Other Comments................................................................................................................33
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ACRONYMS AND ABBREVIATIONS

Acronym/

Abbreviation Definition

Act or CAA Clean Air Act

ACA American Coatings Association

ACC American Chemistry Council

AEGL Acute Exposure Guideline Level

AMOS Ample Margin of Safety

BDT Best Demonstrated Technology

Cal OEHHA California Office of Environmental Health Hazard Assessment

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CFR Code of Federal Regulations

CHIEF Clearinghouse for Emission Inventories and Emissions Factors

CRWI Coalition for Responsible Waste Incineration

CWA Clean Water Act

EJ Environmental Justice

EO Executive Order

EPA U.S. Environmental Protection Agency

EPCRA Emergency Planning and Community Right-to-Know Act

ERPG Emergency Response Planning Guideline

ERT Electronic Reporting Tool

FR Federal Register

HAP Hazardous Air Pollutants

HEM Human Exposure Model

HON National Emission Standards for Organic Hazardous Air Pollutants From the

Synthetic Organic Chemical Manufacturing Industry

HQ Hazard Quotient

IRIS Integrated Risk Information System

LDAR Leak Detection and Repair

MACT Maximum Achievable Control Technology

MOA Mode of Action

NACAA National Association of Clean Air Agencies

NAS National Academy of Sciences

NATA National Air Toxics Assessment

NEI National Emissions Inventory

NESHAP National Emission Standards for Hazardous Air Pollutants

OECA Office of Enforcement and Compliance Assurance

OEL Open-Ended Line

OSWRO Off-Site Waste and Recovery Operations

PAH Polycyclic Aromatic Hydrocarbon

PB Persistent and Bioaccumulative
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PHA Process Hazards Analysis

POM Polycyclic Organic Matter

ppm Parts Per Million

PRD Pressure Relief Device

QA Quality Assurance

REL Reference Exposure Level

RfC Reference Concentration

RfD Reference Dose

RQ Reportable Quantity

RTR Risk and Technology Review

SAB Science Advisory Board

SCAQMD South Coast Air Quality Management District

SOCMA Society of Chemical Manufacturers and Affiliates

SOCMI Synthetic Organic Chemical Manufacturing Industry

SSM Startup, Shutdown, and Malfunction

TOSHI Target Organ-Specific Hazard Index

VOC Volatile Organic Compound

VOHAP Volatile Organic Hazardous Air Pollutant
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1.0 Introduction

On July 2, 2014 (79 FR 37850), the U.S. Environmental Protection Agency (EPA) 

proposed to revise the National Emission Standards for Hazardous Air Pollutants (NESHAP) for 

Off-site Waste and Recovery Operations (OSWRO) under the authority of section 112 of the 

Clean Air Act (CAA). This document presents summaries of the comments that were submitted 

in response to this action and our responses to those comments for all comments not discussed in 

the preamble to the final rule. Within each comment summary, the EPA provides one or more 

Docket ID numbers for commenters who raised particular issues. However, the list of commenter 

ID numbers is not meant to be exhaustive. The EPA does not individually identify each and 

every commenter who made a certain point in all instances, particularly in cases where multiple 

commenters express essentially identical arguments. Although portions of the preamble to the 

final rule are paraphrased in this document, to the extent any ambiguity is introduced by

paraphrasing, the preamble itself remains the definitive statement of the rationale for the final 

rule.

Thirteen comment letters were received from industry representatives, governmental 

entities, and environmental advocacy groups during the public comment period. In addition, the 

EPA received one comment letter following the close of the comment period. Although the EPA 

is not required to consider late comments, to the extent practicable, the EPA often attempts to 

consider late comments and our responses to the late comment letter are also presented in this 

document.

A list of the commenters, their affiliations, and the EPA docket number assigned to their 

correspondence is presented in Table 1-1. The EPA Docket contains all comment letters 

submitted and the comments are available for viewing at the EPA Docket Center Reading Room, 

or electronically through http://www.regulations.gov by searching Docket ID No. EPA-HQOAR-2012-0360 by docket number.
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TABLE 1-1. LIST OF COMMENTERS ON PROPOSED NATIONAL EMISSION 

STANDARDS FOR HAZARDOUS AIR POLLUTANTS

Document 

IDa,b Commenter Affiliation

57 Donald R. Schregardus U.S. Department of the Navy (Navy)

58 Russell A. Wozniak The Dow Chemical Company (Dow)

59 G. Vinson Hellwig and 

Robert Colby

The National Association of Clean Air Agencies 

(NACAA)

60 David Darling and 

Javaneh Nekoomaram

American Coatings Association (ACA)

61 Lorraine Krupa Gershman American Chemistry Council (ACC)

62 Richard Krock The Vinyl Institute (VI)

63 Emma Cheuse and Jim

Pew

Sierra Club and California Communities Against 

Toxics (Sierra)

64 Kevin D. McGrath Veolia ES Technical Solutions, L.L.C. (Veolia)

65 Melvin E. Keener Coalition for Responsible Waste Incineration 

(CRWI)

66 Michel R. Benoit Cement Kiln Recycling Coalition (CKRC)

67 Scott Kuhn Clean Harbors

68 John Dege E. I. DuPont de Nemours (DuPont)

69 Chris L. Manley Eastman Chemical Company (Eastman)

70 Repeat submission of comment 0063

71 Melvin E. Keener (late 

comment)

Coalition for Responsible Waste Incineration 

(CRWI)

72 25 attachments to comment 0063

a Document ID identifies comments found in Docket No. EPA-HQ-OAR-2012-0360 by document number.

b

Individual comments from the public (and attachments submitted with comments) submitted to the docket 

are assigned a unique 4-digit docket number that follows the base docket number (i.e., EPA-HQ-OAR-2012-

0360-XXXX, where “XXXX” represents the unique 4-digit document docket number). The unique document 

docket numbers presented in this table and document represent that unique docket number without the 

preceding 0s. For example, docket number EPA-HQ-OAR-2012-0360-0057 is presented as 57 in this table and 

within the text of this document. 

The following sections of this document summarize comments received on the proposed 

standards for the OSWRO source category, for all comments not discussed in the preamble to the 

final rule, as well as the EPA’s responses to these comments. For the purpose of orderly

presentation, the comments have been categorized under the following topics:

Section 2: Risk-Related Assessment and Standards

Section 3: Startup, Shutdown, and Malfunction Exemption

Section 4: Electronic Reporting Requirements

Section 5: Equipment Leak Provisions

Section 6: Tank Provisions

Section 7: Control Device, Performance Testing, and Monitoring Provisions

Section 8: Other Comments
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2.0 Risk-Related Assessment and Standards

2.1 Risk Assessment Data and Methodology

Comment 2.1.1: Commenter 59 recommends that the EPA consider risk based on 

potential or allowable emissions because emissions and associated impacts could increase over 

time, and analyses based on actual emissions may underestimate residual risk. The commenter 

notes that the thresholds for major source status were based on maximum potential-to-emit, and 

permits are issued based on potential emissions. Further, the commenter argues that limiting the 

scope of risk assessments to actual emissions would be inconsistent with the applicability

sections of Part 63 rules. While acknowledging that the EPA used allowable emissions in parts of 

the rulemaking, the commenter encourages the EPA to use allowable emissions also for acute 

health risks.

Response 2.1.1: Consistent with previous risk assessments, the EPA considers both

allowable and actual emissions in assessing chronic risks under section 112(f)(2). (See, e.g., 

National Emission Standards for Coke Oven Batteries (70 FR 19998-19999, April 15, 2005); 

proposed and final National Emission Standards for Organic Hazardous Air Pollutants from the 

Synthetic Organic Chemical Manufacturing Industry (71 FR 34428, June 14, 2006, and 71 FR 

76603, December 21, 2006). This approach is both reasonable and consistent with the flexibility 

inherent in the Benzene NESHAP framework for assessing acceptable risk and ample margin of 

safety. As a general matter, modeling allowable emission levels is inherently reasonable since 

this reflects the maximum level sources could emit and still comply with national emission 

standards. But it is also reasonable to consider actual emissions, where such data are available, 

in the acceptable risk and ample margin of safety analyses. See National Emission Standards for 

Coke Oven Batteries, 70 FR 19992, 19998 (April 15, 2005). The commenter claims that limiting 

our review to actual emissions would be inconsistent with the applicability section of Part 63 

rules. As explained, however, we did not limit our review to actual emissions. 

The commenter also urges the Agency to rely on allowable emissions for the purpose of 

our acute assessment. The use of allowable emissions was not considered due to the conservative 

assumptions used to gauge worst-case potential acute health effects. The conservative 

assumptions built into the acute health risk screening analysis include: (1) use of peak 1-hour 

emissions that are on average ten times the annual average 1-hour emission rates; (2) that all 

emission points experience peak emissions concurrently; (3) worst-case meteorology (from 1 

year of local meteorology); and (4) that a person is located downwind at the point of maximum 

impact during this same 1-hour period. Thus, performing an acute screen based on allowable 

emissions would be overly conservative and at best, of questionable utility to decision makers.

Comment 2.1.2: Commenter 59 states that the use of the census block centroid dilutes 

the effect of sources’ emissions, as the maximum point of impact can be far from the centroid 

and may be at or near a facility’s property line, and suggested that the risks for a source category 

be based on the risks to the maximally exposed individual.

Response 2.1.2: As we have noted in the development of previous RTRs, such as the 

Hazardous Organic NESHAP (HON) RTR (71 FR 76603, December 21, 2006), in a nationalscale assessment of lifetime inhalation exposures and health risks from facilities in a source 

category, it is appropriate to identify exposure locations where it may be reasonably expected 
4

that an individual will spend a majority of his or her lifetime. Further, in determining chronic 

risks, it is appropriate to use census block information on where people actually reside to locate 

the estimation of exposures and risks to individuals living near such facilities.

Census blocks are the finest resolution available as part of the nationwide population 

data (as developed by the US Census Bureau); each is typically comprised of approximately 40 

people of about 10 households. In the EPA risk assessments, the geographic centroid of each 

census block containing at least one person is used to represent the location where all the people 

in that census block live. The census block centroid with the highest estimated exposure then 

becomes the location of maximum exposure, and the entire population of that census block is 

assumed to experience the maximum individual risk. In some cases, because actual residence 

locations may be closer to or farther from facility emission points, this may result in an 

overestimate or underestimate of the actual annual concentrations (although there is no 

systematic bias for average levels). Given the relatively small dimensions of census block in 

densely-populated areas, there is little uncertainty introduced by using the census block 

centroids in lieu of actual residence locations. There is the potential for more uncertainty when 

the census block are larger, although there is still no systematic bias. The EPA concludes that 

the most appropriate locations at which to estimate chronic exposures and risks are the census 

block centroids because: 1) census blocks are the finest resolution available in the national 

census data; 2) facility fence lines do not typically represent locations where chronic exposures 

are likely (i.e., people do not typically live at the fence line of facilities); and 3) there is no bias 

introduced into the estimate of the maximum individual risk (MIR) by using census block 

centroid locations.

This has been the EPA’s approach for estimating chronic maximum individual exposures 

and risks throughout the RTR program. In addition, in its peer review of the methodologies used 

to estimate risks as part of the RTR rulemaking efforts, the EPA’s Science Advisory Board (SAB) 

endorsed this approach.1

In addition to the approach described above, the EPA recognizes that where a census 

block centroid is located on industrial property or is large and the centroid is less likely to be 

representative of the block’s residential locations, the block centroid may not be the appropriate 

surrogate. For this source category, as described in the risk assessment document available in 

the docket, in cases where a census block centroid was within 300 meters of any emission source 

(and therefore possibly on facility property), we viewed aerial images of the facility to determine 

whether the block centroid was likely located on facility property. Likewise, we examined aerial 

image of all large census blocks within one kilometer of any emission source. If the block 

centroid did not represent the residential locations within that block, we relocated it to better 

represent them and/or we added receptors for residences nearer to the facility than the centroid. 

For this source category, we added several receptors for census blocks where the centroid 

location was not representative of the residential locations. Appendix 7 of the risk assessment, 

entitled “Residual Risk Assessment for the Off-Site Waste and Recovery Operations Source 

 

1 U.S. Environmental Protection Agency, Office of the Administrator Science Advisory Board. 

Review of EPA’s draft entitled, “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-SAB-10-007. May 7, 2010. 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf.
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Category” provide additional information on these changes.

Comment 2.1.3: Commenter 63 states that the EPA cannot assume that hazardous air 

pollutants (HAP) with no peer-reviewed reference values for cancer or non-cancer effects have 

zero risk. The commenter states that the EPA must select health protective values based on the 

information it has or, at a minimum, add an uncertainty factor to the risk estimates. The 

commenter also requests that the EPA clearly state which HAP emitted by this source category

have no health reference values. 

Response 2.1.3: This issue was addressed by the EPA’s SAB in its May 7, 2010 response 

to the EPA Administrator.2In that response, the SAB Panel recommended that, for HAP that do 

not have dose-response values from the EPA’s hierarchy list, the EPA should consider and 

utilize, as appropriate, additional sources for such values that have undergone adequate and 

rigorous scientific peer review. The SAB panel further recommended that the inclusion of 

additional sources of dose-response values into the EPA’s hierarchy should be adequately 

documented in a transparent manner in any residual risk assessment case study. We agree with 

this approach and have considered other sources of dose-response data when conducting our 

risk determinations under RTR. However, in some instances no sources of information beyond 

the EPA’s hierarchy are available.

The EPA notes that we did state which HAP currently have no reference value. In the risk 

assessment document, Table 3.1-1 lists all the HAP emitted by the source category, and indicates 

whether there is an available cancer, chronic noncancer and/or acute dose-response value. 

Comment 2.1.4: Commenter 59 states that the use of Acute Exposure Guideline Levels 

(AEGLs) or Emergency Response Planning Guidelines (ERPGs) in residual risk assessments is 

not appropriate and does not ensure that public health is adequately protected from the acute 

impacts of HAP exposure. These limits were developed for accidental release emergency

planning and are not appropriate for assessing daily human exposure scenarios. In the December 

2002 EPA document, "A Review of the Reference Dose and Reference Concentration 

Processes," EPA stated that the primary purpose of the Acute Exposure Guideline Level (AEGL) 

program is to develop guidelines for once-in-a-lifetime, short-term exposures to airborne 

concentrations of acutely toxic chemicals. They are not meant to evaluate the acute impacts from 

routine emissions that occur over the life of a facility. Unlike the reference concentrations (RfCs) 

for chronic exposures, the AEGLs and ERPGs do not include adequate safety and uncertainty 

factors and cannot be relied upon to protect the public from the adverse effects of exposure to 

toxic air pollutants. The commenter supports the EPA’s increased reliance on the California 

Reference Exposure Levels (RELs) to address acute exposures in the residual risk assessments, 

and the commenter continued to urge EPA to use RELs for these assessments. 

Response 2.1.4: The EPA does not rely exclusively upon AEGL or ERPG values for 

assessment of acute exposures. Rather, the EPA’s approach is to consider various acute health 

effect reference values (see 79 FR 37857), including the California REL, in assessing the 

potential for risks from acute exposures. To better characterize the potential health risks 

associated with estimated acute exposures to HAP, and in response to a key recommendation

 

2 The SAB peer review of RTR Risk Assessment Methodologies is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf.
6

from the SAB’s peer review of the EPA’s RTR risk assessment methodologies,3 we generally 

examine a wider range of available acute health metrics (e.g., RELs, AEGLs) than we do for our 

chronic risk assessments. This is in response to the SAB’s acknowledgement that there are 

generally more data gaps and inconsistencies in acute reference values than there are in chronic 

reference values. In some cases, when Reference Value Arrays4for HAP have been developed, 

we consider additional acute values (i.e., occupational and international values) to provide a 

more complete risk characterization. As discussed in the preamble to the proposed rule (79 FR 

37857), the exposure guidelines EPA considers depends on which exposure guidelines are 

available for the various hazardous air pollutants emitted. The EPA uses AEGL and ERPG 

values (when available) in conjunction with REL values (again, when available) to characterize 

potential acute health risks. However, it is often the case that HAP do not have all of these acute 

reference benchmark values. In these instances, the EPA describes the potential acute health risk 

in relation to the acute health values that are available. Importantly, when interpreting the 

results, we are careful to identify the benchmark being used and the health implications 

associated with any specific benchmark being exceeded. 

Comment 2.1.5: Commenter 63 states that the EPA must account for the health risk from 

flares, especially badly performing flares, in its assessment of risk. Where the EPA does not have 

enough information to assess the actual performance and emissions from flares, default values 

should be used.

Response 2.1.5: The EPA disagrees with the commenter that it has failed to adequately 

assess the risk from the one known flare in this source category. We incorporated reported 

emissions from all emission points, including this flare in our risk assessment. The commenter 

has failed to provide the EPA with evidence that the one known flare in this source category is

underperforming, that any reported emissions from this flare is not accurate, or data on how 

such a default factor should be developed. Lacking that information, we do not believe it is 

appropriate to apply a default factor to this flare. The commenter also has not identified any 

other flares in this source category.

Comment 2.1.6: Commenter 63 states that all emissions data the EPA currently has are 

primarily estimates subject to significant error in the estimation calculations. To improve the 

available data, the commenter states that the EPA needs to require remote sensing and 

continuous monitoring to track and measure emissions, with technologies such as differential 

absorption light detection and ranging, solar occultation flux, CEREX UV Hound, and 

Accusense. The commenter also states that in addition or as an alternative, the EPA should 

require continuous emissions monitoring and/or performance tests every year, at a minimum, as 

it has done for other source categories. 

 

3

Id.

4 U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference Values for Formaldehyde in Graphical Arrays of 

Chemical-Specific Health Effect Reference Values for Inhalation Exposures (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R–09/061, and available on-line at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
7

Response 2.1.6: The emissions data for the risk assessment in the proposed rule were 

derived from a combination of industry responses to an EPA questionnaire sent under the 

authority of CAA section 114, the toxics release inventory (TRI) and the National Emissions 

Inventory (NEI). The sources of the data are documented in the docket. We have worked 

diligently with state and local agencies and tribes to improve emission inventories over the 

years, and we have instituted a number of quality assurance (QA) measures to improve data 

received from state and local agencies for the NEI. Additionally, the online data reporting 

system for the TRI contains extensive data quality checks and additional QA analyses are 

performed by EPA staff once the submissions are received. In addition to the broad QA analysis 

the EPA performed on the questionnaire response data for the dataset as a whole, the EPA also 

reviewed the facilities contained in the source category, the emissions units expected to be 

included for the processes in the source category, coordinates and stack parameters, and the 

HAP compounds and emission levels typically seen. A preliminary data set, containing NEI data, 

was also reviewed by an industry trade group, individual companies and several state air 

agencies, and the EPA revised the NEI data where we concluded comments from this review 

supported such adjustment. The memorandum, Development of the RTR Emissions Dataset for 

the Off-Site Waste and Recovery Operations Source Category, available in the docket for this 

action, sets forth a detailed explanation of the emissions data compilation and review that the 

EPA performed for the OSWRO source category. As part of the proposal, we also made the data 

set available for review using a RTR data review tool in the docket and solicited comments on 

the data set. The RTR review of the proposal data sets act as an external third party review 

mechanism of the RTR data set, and we note that no comments regarding the RTR data set were 

received during the public comment period for the proposed rulemaking. Several opportunities 

have been provided to review the data used in the current rulemaking. Through the NEI and TRI 

QA procedures, QA of industry submitted data, industry, state, and NACAA review, public 

comment on proposal files, source category-specific engineering reviews, and modeling, 

improvements to the data files have been made. We believe the data set used in this rulemaking is

sufficiently accurate and complete and constitutes the best information the EPA has for 

conducting the RTR for this source category.

Comment 2.1.7: Commenter 63 claims the EPA lags behind the best available science to 

address the real-world health risk for the individual most exposed to OSWRO emissions and 

must apply this science in the rulemaking under CAA section 112(f)(2). In particular, the 

commenter believes the EPA should follow the recommendations of the National Academy of 

Sciences (NAS) and the SAB on the key issues that affect the most-exposed and most vulnerable 

populations, especially children and environmental justice (EJ) communities. The commenter 

states the EPA must consider the science and update its risk assessment in, at least, each of the 

following ways before finalizing the rule:

 Account for individual-level vulnerability in this risk assessment by better 

incorporating the vulnerability of children, early-life exposures, and the developing 

fetus into risk assessment methods.

 Account for increased susceptibility by using California Office of Environmental 

Health Hazard Assessment (Cal OEHHA) Cancer Guidelines (Age-Dependent 

Adjustment Factors) for all carcinogens, not just known mutagens and include prenatal susceptibility.

 For chronic non-cancer risk, consult and apply child-specific reference values (such 
8

as the Cal OEHHA values), where available.

 If child-specific reference values are unavailable, consult science on early exposure 

impacts, and use an additional default factor of at least 10X.

Response 2.1.7: We disagree with the general comment that the EPA should adopt the

Cal OEHHA child-protective scientific approach on cancer. The EPA has an approach for 

selecting appropriate health benchmark values and in general, this approach places greater 

weight on the EPA derived health benchmarks than those from other agencies (see

http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf). Notably, this approach

favoring EPA benchmarks (when they exist) over all others has been endorsed by the SAB. 

Further, the EPA is currently evaluating whether it is appropriate to use the Cal OEHHA childspecific reference doses, and we note that because there are currently no such values for HAP

inhalation, their current utility would be limited to persistent and bioaccumulative (PB)-HAP, 

which may be associated with non-negligible ingestion exposures. That is, before using these 

child-specific reference doses (RfDs), the EPA would need to evaluate whether they have been 

appropriately derived.

We also disagree with the comment that the risk assessment for this source category does 

not consider the groups that may be most at-risk (e.g., pregnant women). When the EPA derives 

exposure reference concentrations and unit risk estimates for metal HAP, it also considers the 

most sensitive populations identified in the available literature, and importantly, these are the 

values used in our risk assessments (see US EPA. (2002). A review of the reference dose and 

reference concentration processes. EPA/630/P-02/002F. Risk Assessment Forum, Washington, 

DC. Available online at http://www.epa.gov/raf/publications/pdfs/rfd-final.pdf. With respect to 

maternal exposure in utero specifically, we are unaware of literature that would allow for a 

robust characterization of risk during this stage of development.

We acknowledge that population subgroups, including children, may have a potential for 

risk that is greater than the general population due to greater relative exposure and/or greater 

susceptibility to the toxicant. As explained in previous actions, including the final HON RTR (71 

FR 76610-76611), the assessments we undertake to estimate risk account for this potential 

vulnerability. With respect to exposure, the risk assessments we perform implicitly account for 

this greater potential for exposure by assuming lifetime exposure, in which populations are 

conservatively presumed to be exposed to airborne concentrations at their residence 

continuously, 24 hours per day for a full lifetime, including childhood. With regard to children’s 

potentially greater susceptibility to non-cancer toxicants, the assessments rely on EPA (or 

comparable) hazard identification and dose-response values which have been developed to be 

protective for all subgroups of the general population, including children.

For example, a review5of the chronic reference value process concluded that the EPA’s 

reference concentration (RfC) derivation processes adequately considered potential 

susceptibility of different subgroups with specific consideration of children, such that the 

resultant RfC values pertain to the full human population “including sensitive subgroups,” a 

phrase which is inclusive of childhood. With respect to cancer, the EPA uses the age-dependent 

adjustment factor approach referred to by the commenter, but limits the use of those factors only 

to carcinogenic pollutants that are known to act via mutagenic mode of action, in contrast to the 

OEHHA approach, which uses them across the board for all carcinogens regardless of mode of 

 

5 U.S. EPA. A Review of the Reference Dose and Reference Concentration Processes. U.S. Environmental 

Protection Agency, Risk Assessment Forum, Washington, DC, EPA/630/P-02/002F, 2002. 
9

action (MOA). In lieu of chemical-specific data on which age or life-stage specific risk estimates 

or potencies can be determined, default age dependent adjustment factors can be applied when 

assessing cancer risk for early-life exposures to chemicals which cause cancer through a 

mutagenic MOA. The estimated risks must also be considered in the context of the full set of 

assumptions used for this risk assessment. For example, we used a health-protective assumption 

of a 70-year exposure duration in our risk estimates; however, using the national average 

residency time of 12 years would reduce the estimate of risk by roughly a factor of 6. Our unit 

risk estimates for HAP are considered a plausible upper-bound estimate; actual potency is likely 

to be lower and some of which could be as low as zero. After considering these and other factors, 

we continue to consider the risks from emissions after application of the revisions to the 

NESHAP for this source category to provide an ample margin of safety (consistent with the 

Benzene NESHAP framework).

Comment 2.1.8: Commenter 63 states that the EPA failed to perform an adequate 

multipathway risk assessment. One reason the commenter states the assessment is inadequate is 

that it does not account for all the PB-HAP pollutants. The commenter asserts that the EPA’s 

choice to restrict the multipathway screening assessment to only HAP that bioaccumulate is not 

supported by the 2003 Risk Assessment Guidance because it ignores other HAP that persist and 

accumulate in soils. In addition, the commenter states that the EPA should include all metals in 

the multipathway risk assessment, as recommended by California’s OEHHA and also 

recommends that naphthalene, a polycyclic aromatic hydrocarbon (PAH), be considered a 

polycyclic organic matter (POM), which is listed as a PB-HAP. In addition, the commenter notes 

that the EPA did not assess all exposure routes, did not use the information from the 

multipathway analysis in the overall risk analysis, and did not add the multipathway risk found to 

the inhalation risk. The commenter asserts that the EPA may not assume that emissions under the 

multipathway screening levels are not significant enough to require a full analysis. The 

commenter opines that the EPA should update the incidental soil ingestion factors it uses in its 

multipathway risk assessments to fully account for the greater multipathway exposure and risk 

for children.

Response 2.1.8: We believe our multipathway assessment is a reasonable technical 

analysis of risk to human health from OSWRO emissions of HAP via non-inhalation pathways 

based on the information and analytical tools currently available to the EPA. In the Air Toxics 

Risk Assessment Reference Library, we developed the current PB-HAP list considering all of the 

available information on persistence and bioaccumulation (see http://www2.epa.gov/fera/airtoxics-risk-assessment-reference-library-volumes-1-3), specifically Volume 1 Appendix D). (The 

Air Toxics Risk Assessment Reference Library provides information on the fundamental 

principles of risk-based assessment for air toxics and how to apply those principles in different 

settings (e.g., facility-specific) as well as strategies for reducing risk at the local level.) This list 

considered HAP identified as PB-HAP by other EPA Program Offices (e.g., the Great Waters 

Program), as well as information from the persistent, bioaccumulative and toxic (PBT) profiler 

(see http://www.pbtprofiler.net). This list was peer-reviewed by the SAB and found to be 

acceptable, and therefore we consider it to be reasonable for use in the RTR program. Based on 

these sources and the limited available information on the persistence and bioaccumulation of 

other HAP, we do not believe that the potential for multipathway risk from other HAP rises to 

the level of the PB-HAP currently on the list.

Naphthalene is not treated as a POM chemical in the multipathway analyses. 
10

Naphthalene is listed individually as a HAP under Section 112(b) of the Clean Air Act. POM 

also is listed as a HAP under Section 112(b) and is defined as organic compounds with more

than one benzene ring and a boiling point greater than or equal to 100 degrees Celsius. This 

definition potentially could include naphthalene. However, naphthalene is short-lived in 

environmental media due to its tendency to volatilize and biodegrade and, consequently, will not 

build up in environmental media over time.6It has a moderate affinity for lipids and will undergo 

short-term bioaccumulation is tissues; however, biochemical processes lead to its 

biodegradation and elimination. Because it is neither persistent nor bioaccumulative, we do not 

consider it a PB-HAP in our multipathway risk analyses and believe that its inclusion as a PBHAP would result in less accurate and less meaningful estimates of media concentrations and 

multipathway risk. 

We did not combine the inhalation and multipathway risk assessment results for each 

pollutant because it is inappropriate to do so. The multipathway risk assessment conducted for 

proposal was a screening-level assessment (i.e., Tier 1). It used highly conservative assumptions 

designed to ensure that facilities with results below the screening threshold values did not have 

the potential for multipathway impacts of concern. The screening scenario is a hypothetical 

scenario. It is inappropriate to combine the results of a refined inhalation assessment, which 

produces a quantitative result, with a screening-level multipathway assessment, which produces 

a “yes/no” result. In situations where we have previously summed the inhalation and 

multipathway assessment results (e.g., secondary lead smelters), it was for two refined 

assessments, and still serves as an overestimate of potential risks given that it is highly unlikely 

that the same receptor has the maximum results in both assessments.

We further note that we generally draw no bright lines of acceptability regarding cancer 

or noncancer risks from source category HAP emissions, and that it is always important to 

consider the specific uncertainties of the emissions and health effects information regarding the 

source category in question when deciding exactly what level of cancer and noncancer risk 

should be considered acceptable. In addition, the source category-specific decision of what 

constitutes an acceptable level of risk should be a holistic one; that is, it should simultaneously 

consider all potential health impacts -- chronic and acute, cancer and noncancer, and 

multipathway -- along with their uncertainties, when determining the acceptable level of source 

category risk. In other words, we look at the risk numbers within the context of uncertainty 

associated with emissions and health benchmark values. The Benzene NESHAP decision 

framework of 1989 acknowledged this; in today’s world, such flexibility is even more imperative, 

because new information relevant to the question of risk acceptability is being developed all the 

time, and the accuracy and uncertainty of each piece of information must be considered in a 

weight-of- evidence approach for each decision. This relevant body of information is growing 

fast (and will continue to grow even faster), necessitating a flexible weight-of-evidence approach 

that acknowledges both complexity and uncertainty in the simplest and most transparent way 

possible. While this challenge is formidable, it is nonetheless the goal of the EPA’s RTR 

decision-making, and it is the goal of the risk assessment to provide the information to support 

the decision-making process.

Regarding incidental soil contamination, the EPA has estimated risks from both direct 

 

6 US Agency for Toxic Substances and Disease Registry. 2005. Toxicological Profile for Naphthalene, 1-

Methylnaphthalene, and 2-Methylnaphthalene. 

http://www.atsdr.cdc.gov/ToxProfiles/tp.asp?id=240&tid=43#bookmark08.
11

and indirect pathways. Direct routes of exposure include direct ingestion of soil and exposure 

through dermal contact. However, because it has been demonstrated in past analyses that 

exposure levels associated with dermal contact are but a small fraction of exposure levels 

associated with ingestion and inhalation pathways, dermal exposures were not assessed for this 

source category.

Comment 2.1.9: Commenter 63 states that the EPA has not used a high enough 

emissions factor to account for acute risks. The commenter states the EPA used an emissions 

factor of 1 that fails to adequately account for additional health risk from malfunctions, 

considering that a facility could emit 100 times more than its usual emissions during a control 

equipment failure if it usually controls 99% of emissions. 

Response 2.1.9: The acute risk assessment methodology uses a tiered, iterative approach 

that begins with an assessment of an approximation of a worst-case exposure. To this end, we 

assumed that peak 1-hour emissions are equal to 10 times the average 1-hour emissions rate 

(rather than a factor of 1 as stated by the commenter), which is only one of the worst-case 

assumptions that we made in our acute health risk screening analysis. Other worst-case 

assumptions included:

 For facilities with multiple emission points, peak 1-hour emissions were assumed to 

occur at all emission points at the same time.

 For facilities with multiple emission points, 1-hour concentrations at each receptor were 

assumed to be the sum of the maximum concentrations due to each emission point, 

regardless of whether those maximum concentrations occurred during the same hour.

 Worst-case meteorology (from one year of local meteorology) was assumed to occur at 

the same time the peak emission rates occur. The recommended EPA local-scale 

dispersion model, AERMOD, is used for simulating atmospheric dispersion.

 A person was assumed to be located downwind at the point of maximum impact during 

this same 1-hour period, but no nearer to the source than 100 meters.

 The maximum impact was compared to multiple short-term health benchmarks for the 

chemical being assessed to determine if a possible acute health risk might exist.

With regards to the failure of a control device, this would constitute a violation of the 

emission standard. The acute risk emissions factor is designed to account for fluctuations in 

emissions for facilities complying with the standards, not for facilities in non-compliance. 

Therefore, it would be inappropriate to use the emissions factor suggested by the commenter for 

purposes of determining whether the NESHAP’s current requirements are in need of revision 

under section 112(f)(2).

Comment 2.1.10: Commenter 63 states that the EPA should analyze risk including 

emissions that may occur above the existing MACT standards, considering malfunctions and 

violations. The commenter states that the EPA must assess public health risk based on the 

likelihood of such events and suggests that the EPA develop and apply a factor to the risk results 

based on available malfunction and violation data.

Response 2.1.10: We disagree with the commenter that emissions that exceed standards 

and are violations, whether or not they are caused by malfunction events, should be considered 

as part of the risk analysis for purposes of determining the sufficiency of pre-existing standards, 

particularly when we are revising the standards to eliminate any excused periods of non-
12

compliance during upset periods. The purpose of the risk review is to evaluate whether the 

emission limits -- the “standards promulgated pursuant to subsection (d),” not the noncompliance with those standards (section 112(f)(2)(A)) -- should be made more stringent to 

reduce the risk posed after compliance with the underlying MACT standard. To the extent that a 

source is violating the underlying MACT standard, no tightening of the emission standard under 

the residual risk rule will avoid or militate against such violations. In other words, a source that 

is violating the emission standard promulgated under section 112(d) would not be any more 

likely to be able to avoid such violations and comply with a different presumably more stringent 

standard promulgated under section 112(f). Such events are violations and subject to 

enforcement by the EPA, the states or citizens, and an action for injunctive relief is the most 

effective means to address violations, whether or not they are caused by malfunctions, if an 

emissions event poses a significant health or environmental risk.

Furthermore, the conservative estimates built into the acute risk assessment are sufficient 

to gauge worst-case potential acute health effects. The conservative estimates built into the 

assessment include worst-case meteorology, emissions at ten times the maximum peak emission 

rate from all point sources simultaneously, and the sum of the maximum impact of each emission 

source, regardless of receptor location. Thus, even if we were to consider emissions that are in 

violation of the standard, we do not believe that they would result in any different level of control 

than we are promulgating here.

Comment 2.1.11: Commenter 67 questions why the EPA used NEI data from 2005 

instead of the newer 2011 NEI data for the risk analysis. 

Response 2.1.11: As noted in the preamble to the proposed rule and the emissions data 

documentation available in the docket for this action, Development of the RTR Emissions 

Dataset for the Off-Site Waste and Recovery Operations Source Category, we used the best data 

available to us in the risk assessment. Of the 38 facilities modeled in the risk assessment, data 

from industry gathered under CAA section 114 was used for 19 facilities. For the remaining 

facilities where this data was not available, we used a combination of NEI, toxics release 

inventory (TRI) and emissions inventory system (EIS) data. In an effort to ensure emissions were 

assigned to the OSWRO source category wherever possible, an emissions summary was 

developed by HAP category name at the facility level for side by side comparison of emissions 

data from the 2005 NEI, 2008 EIS, and 2008, 2009, and 2010 TRI. When this data was compiled 

and modeled in the summer of 2013, the 2011 NEI data was not yet available and was not 

considered. As the 2010 TRI contained the most recent data available, these data were generally 

used to fill gaps in or replace the 2005 NEI data, which represented the most complete data 

available, including data for specific emissions points, emissions point type identifiers, HAP 

emitted, and emissions release parameters.

2.2 Consideration of Risks from Entire Facilities, Industrial Clusters, and

Other Sources in Risk Assessment

Comment 2.2.1: Commenter 63 states that the EPA should assess the cumulative burden 

of exposures to multiple pollutants and sources via multiple pathways. To do this, the commenter 

suggests that the EPA aggregate inhalation and non-inhalation-based cancer risks; include the 

interaction of multiple pollutants; and account for exposure to multiple emissions sources 

including other emissions sources at the facilities and from other sources of toxic air pollutants in 
13

the area. The commenter states that until the EPA has a specific mechanism for estimating total 

exposures, use of a default factor of at least 10X should be incorporated in the risk assessments.

Response 2.2.1: We have combined risk assessment results to the extent that it is 

appropriate to do so. We consider the effect of mixtures of carcinogens and use a target organspecific hazard index (TOSHI) approach for our chronic noncancer assessments. We do not use 

a TOSHI approach for our acute analyses nor do we combine the results of our inhalation and 

multipathway assessments.

For the OSWRO source category, the EPA conducted an assessment of the cumulative 

cancer risks from emitted carcinogens and the cumulative noncancer hazard indices from all 

emitted non-carcinogens affecting the same target organ system for both the source category 

emissions and the facility-wide emissions. While the incorporation of additional background 

concentrations from the environment in our risk assessments (including those from mobile 

sources and other industrial and area sources) could be technically challenging, they are neither 

mandated nor barred from our analysis. In developing the decision framework in the Benzene 

NESHAP currently used for making residual risk decisions, the EPA rejected approaches that 

would have mandated consideration of background levels of pollution in assessing the 

acceptability of risk, concluding that comparison of acceptable risk should not be associated 

with levels in polluted urban air (54 FR 38044, 38061, September 14, 1989). Background levels 

(including natural background) are not barred from the EPA’s ample margin of safety (AMOS) 

analysis, and the EPA may consider them, as appropriate and as available, along with other 

factors, such as cost and technical feasibility, in the second step of its section 112(f) analysis.

This assessment excludes background contributions because the available data are of insufficient 

quality upon which to base a meaningful analysis.

We disagree with the comment that we failed to consider or account for cumulative risk. 

The EPA modeled whole-facility risks for both chronic cancer and non-cancer impacts to 

understand the risk contribution of the sources within the OSWRO source category. The 

individual cancer risks for the source category were aggregated for all carcinogens. In assessing 

noncancer hazard from chronic exposures for pollutants that have similar modes of action or 

(where this information is absent) that affect the same target organ, we aggregated the hazard 

quotients (HQ). This process creates, for each target organ, a TOSHI, defined as the sum of 

hazard quotients for individual HAP that affect the same organ or organ system. All TOSHI 

calculations presented here were based exclusively on effects occurring at the “critical dose” 

(i.e., the lowest dose that produces adverse health effects). Whole facility risks were estimated 

utilizing the 2005 NEI, with updated facility-wide and source category data files developed by 

the EPA through emission data updates from industry, states, and NACAA. We also disagree 

with the commenter’s assertion that additional quantitative assessment of risks from sources 

outside the source category is required under the statute. The statute requires the EPA to provide 

the quantitative risk information necessary to inform RTR regulatory decisions, and to this end, 

the EPA conducts a comprehensive assessment of the risks associated with exposure to the HAP 

emitted by the source category and supplements that with additional information that is 

available about other possible concurrent and relevant risks.

As described in the risk assessment report (available in the docket for this action), we do 

not sum results of the acute noncancer inhalation assessment to create a combined acute risk 

number that would represent the total acute risk for all pollutants that act in a similar way on the 

same organ system or systems (similar to the chronic TOSHI). As noted in previous responses, 

the worst-case acute screen is already a conservative scenario. That is, the acute screening 
14

scenario assumes worst-case meteorology, peak emissions for all emission points occurring 

concurrently and an individual being located at the site of maximum concentration for an hour. 

Thus, as noted in section 2.7.2 of the Draft Residual Risk Assessment for the Off-Site Waste and 

Recovery Operations Source Category (Docket Item No. EPA-HQ-OAR-2012-0360-0003), 

“because of the conservative nature of the acute inhalation screening and the variable nature of 

emissions and potential exposures, acute impacts were screened on an individual pollutant basis, 

not using the TOSHI approach.”

We did not combine the inhalation and multipathway risk assessment results for each 

pollutant because it is inappropriate to do so. The multipathway risk assessment conducted for 

proposal was a screening-level assessment (i.e., Tier 1). It used highly conservative assumptions 

designed to ensure that facilities with results below the screening threshold values did not have 

the potential for multipathway impacts of concern. The screening scenario is a hypothetical 

scenario, and due to the theoretical construct of the screening model, exceedances of the 

thresholds are not directly translatable into estimates of risk or hazard quotients for these 

facilities. In situations where we have previously summed the inhalation and multipathway 

assessment results (e.g., secondary lead smelters), it was for two refined assessments, and still 

serves as a conservative overestimate of potential risks given that it is highly unlikely that the 

same receptor has the maximum results in both assessments.

2.3 Consideration of Demographics in Risk Assessment

Comment 2.3.1: Commenter 59 commends the EPA for considering EJ issues in this 

proposal. However, the commenter suggests the EPA rule writers work with the EPA’s Office of 

Environmental Justice to develop specific criteria and guidance on how to interpret and apply the 

outcomes of EJ analyses in the rulemaking process. The commenter also specifically suggests 

that the EPA use a 5-kilometer radius rather than 3-mile radius in its demographic analyses; that 

the EPA conduct the demographic analysis for all people projected to experience risk greater 

than 1-in-1 million for cancer or an HQ above one, consistent with the approach used for the 

Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks source 

category; and that the analysis be conducted using maximum allowable emissions..

Response 2.3.1: The commenter is correct that we performed the demographic analyses 

for the OSWRO source category differently than we did for the October 2010 proposed RTR for 

the chrome source categories. We performed the demographic analyses for the chrome source 

categories using two approaches as examples of how such analyses might be developed, and 

invited public comment on the approaches used and the interpretations made from the results. In 

the first approach, we focused the analysis on the total populations residing within 5 km of each 

facility, regardless of their estimated risks, and examined the distributions across various 

demographic groups within those 5 km circles. That analysis was a “proximity” analysis in that 

it considered only the distance from the emission sources to surrounding populations, and not 

the estimated risks to those populations

In the second approach, we focused the analysis on the populations within 5 km of any 

facility estimated to have exposures to HAP which result in cancer risks of 1-in-1 million or 

greater or non-cancer hazard indices of 1 or greater. We examined the distributions of those 

risks across various demographic groups. In each approach, we compared the percentages of 

particular demographic groups to the total number of people in those demographic groups 

nationwide. We stated in the proposed rule for the chrome source categories that in future rules 
15

we planned to extend the analyses to cover the entire modeled domain for a facility (50 km 

radius) to capture all individuals with risks above 1-in-1 million or greater or non-cancer 

hazard indices of 1 or greater. We also stated that generally we have found that using a 5 km 

radius in the analysis will capture more than 90 percent of the individuals with cancer risks 

above 1-in-1 million.

In the February 2012 supplemental proposal for the RTR for the chrome source 

categories, our demographic analyses included populations within 50 km of each source 

(including those very near the sources) with risks of 1-in-1 million or greater or non-cancer 

hazard indices of 1 or greater (77 FR 6628, Feb. 8, 2012). We did not include analyses using a 5 

km radius in that supplemental proposal nor in the RTR proposal for the OSWRO source 

category. We believe that, where a risk assessment has been performed, it is more informative to 

consider the demographics of all populations (including those beyond 5 km) with elevated risks 

than to limit the demographics analysis to populations located within 5 km of a facility. Where a

risk assessment has been performed, these populations are identified, and the source parameters 

(like the low release height mentioned by the commenter) are taken into account. As discussed 

above, we have found that most exposure locations with the highest estimated risks are within 5 

km of a facility, so extending the radius to 50 km has little impact on an analysis based on risks, 

but makes more sense because 50 km corresponds to the risk modeling radius and includes all 

populations with elevated risk estimates. We also note that we are working with the Office of 

Environmental Justice in an ongoing effort to develop new tools for considering environmental 

justice in rulemakings. 

Comment 2.3.2: Commenter 63 states that the EPA should assess and account for 

increased vulnerability due to socioeconomic status and baseline overall health status in its risk 

assessment, which could be accomplished by adding a default factor to account for 

socioeconomic and other community-based stressors. 

Response 2.3.2: We are not able to determine the baseline health status of individuals or 

communities in a national rulemaking. Individual privacy issues as they relate to health records 

and the costs that would be associated with such an analysis make the analysis infeasible. 

Through the EPA’s interim guidance on EJ and the Action Development Process, the agency is 

encouraging rule writers and policy makers to look at the whole range of factors that impact 

communities and population groups when crafting rules. The EPA is continuing to discuss and 

pilot approaches that are consistent with the agency’s responsibilities regarding EJ as outlined 

in EO 12898. In determining the need for tighter residual risk standards, the EPA strives to limit 

to no higher than 100-in-1 million the estimated cancer risk for persons living near a plant if 

exposed to the maximum pollutant concentration for 70 years and to protect the greatest number 

of persons to an individual lifetime risk of no higher than 1-in-1 million. Considerations are 

made for all people regardless of racial or socioeconomic status, and the EPA does not believe it 

is necessary to establish a default factor to account for socioeconomic and other communitybased stressors.

2.4 Additional Standards to Address Risks

Comment 2.4.1: Commenter 64 states that the EPA’s risk analysis demonstrates that 

current regulations adequately address HAP emissions from OSWRO facilities, and the proposed

emissions controls would not significantly decrease the health risk to the public and would be 
16

costly. The commenter notes the EPA’s assessment of the acceptability of risks and argues that a 

margin of safety analysis and associated emission controls are not warranted.

Response 2.4.1: For the OSWRO NESHAP, we are revising emissions controls for 

equipment leaks and certain tanks concurrently under both the CAA section 112(d)(6) 

technology review and the CAA section 112(f)(2) risk review. As noted in the preamble to the 

proposed rule (79 FR 37853-37854), in keeping with the Benzene NESHAP two-step process for 

developing residual risk standards, in the risk review the EPA first examines risk acceptability 

and then considers whether the existing standards provide for an “ample margin of safety.” The 

two-step process does not conclude with a decision of acceptability. In the second step, the EPA 

determines whether the emissions standards provide an ample margin of safety, considering all 

of the health risks and other health information considered in the acceptability determination, as 

well as other relevant factors. While we proposed that the risks from the OSWRO source 

category are acceptable, we also found that the cancer risk estimates for 210,000 individuals in 

the exposed population were above 1-in-1 million, with an MIR of up to 9-in-1 million, based on 

actual emissions. We then proceeded to the ample margin of safety analysis. For this source 

category, several options for tanks, equipment leaks and process vents were identified. Finding 

that the revised requirements would reduce cancer and non-cancer risks and considering the 

associated costs, economic impacts, and technological feasibility among other information, we 

proposed to revise the standards for these emissions sources under CAA section 112(f). The 

commenter has identified no flaw in our reasons or analysis under either section 112(d)(6) or 

112(f)(2) for adopting the revised requirements.

Comment 2.4.2: Commenter 63 supports the proposed strengthening of emission 

standards in certain ways for leaks and tanks but states that the EPA also refused to strengthen 

the existing standards for parts of the source category, including tanks and process vents, based 

purely on its cost-benefit analysis. The commenter states that EPA used cost as a metric to 

develop revised standards, but that CAA section 112(d)(6) does not mention cost. The 

commenter states that if the EPA is going to use a “cost-effectiveness” metric, it should at least 

assess the cost-per-pound of emission reductions, rather than cost-per-ton, consistent with the 

EPA’s chrome plating rule. 

The commenter also states that the EPA failed to explain the rationale for determining 

why some costs were too high and why other costs were acceptable in the determination of 

additional standards. In addition, the commenter states that the EPA’s approach considered only 

the cost per ton of HAP emission reduction, without assessing relevant factors such as: the 

individual HAPs emitted and the impact those HAPs can have at a level below 1 ton; how many 

people would be affected by the potential emission reductions; where they live and if they are in 

a community containing multiple HAP sources, or whether they face a longstanding 

environmental justice impact. The commenter states that the EPA also did not consider or 

address whether the standards would provide any “margin of safety” to protect public health, 

much less whether the margin is “ample.” Thus, the commenter claims the EPA ignored and 

violated CAA section 112(f)(2).

Response 2.4.2: The EPA disagrees with the commenter’s assertion that the decision not 

to propose more stringent standards other than those for leaks and tanks was based entirely on a 

cost-benefit analysis. To address the requirements of CAA section 112(f)(2) for the OSWRO 

source category, we performed a risk assessment, and based on the results of that assessment, 

made a determination that emissions remaining from the OSWRO source category after 
17

implementation of the existing standards result in risks that are acceptable. We did not consider 

costs as part of that analysis. For purposes of determining whether the existing standards 

provide an ample margin of safety to protect public health, we assessed the additional risk 

reductions that would result from tightening the standards (see 79 FR 37868–37870). 

Specifically, we investigated the possibility of requiring additional emissions controls for leaks, 

tanks and process vents. We proposed revised requirements for leaks and certain tanks, as noted 

in the comment. In our analysis of the control options for process vents and one of the options 

for tanks, we estimated reductions in levels of emissions and maximum individual cancer risks

and other risk metrics, as well as costs (see 79 FR 37869–37870). Based on this analysis, we 

proposed (and are determining in the final rule) that revisions to the existing standards, beyond 

those proposed and finalized for leaks and certain tanks, are unnecessary to provide an ample 

margin of safety.

We note that when assessing the cost-effectiveness of more stringent standards under 

consideration, we have discretion to express emission reductions that would result from such 

standards in any reasonable format, such as costs-per-ton of emissions reduced. We also note 

that changing units used to express emissions reductions makes no substantive difference, e.g., 

$4,000 per ton reduced is equivalent to $2 per lb reduced. Presenting costs in terms of costs-perpound of emissions reduction was appropriate for the chromium electroplating rulemaking, 

where total emissions and emissions reductions of chromium compounds were below one ton.

Further, the EPA disagrees with the commenter that we did not assess the individual 

HAP emitted or the impact those HAP can have at a level below 1 tpy. As noted at proposal (see 

79 FR 37855-37856) and in the risk assessment documentation, we assessed the risks 

considering all individual HAP emissions, regardless of emission level, from the OSWRO source 

category. We also assessed the impact that the potential emission control options would have on 

the level of emissions of the individual HAP and on the risks associated with those emissions, as 

documented in the memorandum, Estimated Risks and Risk Reductions Associated with the 

Emissions Controls Options Considered in the Ample Margin of Safety Analysis for the Off-Site 

Waste and Recovery Operations Source Category, available in the docket for this action. 

Regarding the comment that the EPA should consider whether people live in a 

community containing multiple HAP sources, we note that background risks and contributions to 

risk from sources outside the facilities under review were not considered in the ample margin of 

safety determination for this source category, mainly because of the significant uncertainties 

associated with emissions estimates for such sources (see 79 FR 37866). Our approach here is 

consistent with the approach we took regarding this issue in the Hazardous Organic NESHAP 

(HON) RTR, which the court upheld in the face of claims that the EPA had not adequately 

considered background (NRDC v. EPA, 529 F.3d 1077 (D.C. Cir. 2008)). With regard to the 

comment concerning longstanding environmental justice impacts, we refer to the preamble of the 

proposed rule regarding how we examine environmental justice concerns generally, as well as in 

this specific rulemaking.

Comment 2.4.3: Commenter 63 states that the EPA should revisit or update its presumed 

acceptable level of cancer risk considering information learned about children’s and 

overburdened community’s vulnerability and considering new information on ways to analyze 

and control the impacts of pollutants on human health. The commenter believes that 100-in-1 

million lifetime cancer risk cannot be considered safe or “acceptable.” The commenter also states 

that the EPA should factor in uncertainties and vulnerability factors to adjust the level of non-
18

cancer risk considered acceptable for both chronic and acute exposure.

Response 2.4.3: In 1990, Congress codified in section 112(f) of the CAA the approach we 

use for our residual risk analyses (i.e., the Benzene NESHAP, 54 FR 38044). Under that 

approach, there is no single bright line (e.g., a 100-in-1 million cancer risk) that indicates that 

risk is “acceptable.” Rather, multiple health metrics, including the cancer risk, are considered 

to determine whether the risk is acceptable. Costs cannot be considered at this stage of the 

analysis. However, the analysis of whether risk is acceptable is not the endpoint. Once we 

determine that the existing MACT standards or identify what additional controls are sufficient to 

ensure risk is acceptable, we again review the health metrics in conjunction with considering the 

costs of controls to determine whether further additional controls should be required to provide 

an ample margin of safety to protect public health. The commenter does not explain how science 

has evolved in a way that would undermine the codified framework for determining 

acceptability.

3.0 Startup, Shutdown, and Malfunction Exemption

Comment 3.1: Commenter 58 requests that the EPA provide a six month transition 

period to comply with the revised start-up, shutdown, and malfunction provisions. The 

commenter notes that additional time is needed to review the final amendments and implement 

changes, including physical or operations changes, update internal guidance and perform 

personnel training. 

Response 3.1: We disagree that additional time should be provided to comply with the 

revised SSM provisions. The court decision which vacated the SSM exemptions in the General 

Provisions was decided in 2008 (Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008)). In 

addition, OSWRO facilities have been on notice of EPA’s amendments at least since the 

proposed rule was published on July 2, 2014.Regarding the malfunction reporting and 

recordkeeping requirements, facilities should be able to immediately implement these upon the 

next occurrence of a malfunction.

Comment 3.2: Commenters 65 and 61 argue that standards developed using data 

generated during steady-state conditions should not apply during malfunctions. Specifically, the 

commenters do not agree that the EPA is not required to take malfunctions into account when 

developing emissions standards. The commenters assert that under the proposed amendments, 

the OSWRO standards are not achievable at all times and do not reflect what is achieved by the 

best performing sources because emission limits were developed under steady-state (i.e., normal) 

conditions, and the EPA is now requiring that they also apply during non-steady-state operations 

(i.e., malfunctions). Commenter 65 asserts that standards developed under steady-state 

conditions cannot incorporate the variability that occurs during malfunctions, and the EPA 

cannot predict what emission limits a facility can meet “every day under all operating 

conditions” if those operating conditions now include malfunctions. In reference to CAA section 

112(d)(2) and (3), the commenter states that emission limitations must be “achieved in practice,” 

which means that the EPA must show that at least one facility can meet the emissions limitations 

being promulgated (for new sources) and that a similar showing is required for existing sources. 

The commenter asserts that the EPA has failed to develop standards that are “achieved in 

practice” if even the best performing existing sources are expected to have malfunctions, and 

those malfunctions result in emissions that exceed the standard. In response to EPA’s statement 
19

that the goal of a best controlled source is to operate in such a way as to avoid malfunctions and 

accounting for malfunctions could lead to less stringent standards than levels achieved by a nonmalfunctioning source, the commenter states that congress did not authorize the EPA to set goals 

but to set emission limitations based on what is achievable.

Commenter 65 asserts that the EPA inappropriately relies on the Clean Water Act (CWA)

case Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) in its justification that the 

EPA is not required to factor malfunctions into its standards, because that decision addressed a 

CWA requirement that, unlike the MACT Floor, was intended to require the development of new 

control technology. In response to the EPA’s claim that accounting for malfunctions in setting 

emission standards would be difficult, if not impossible, both commenters state that this does not 

relieve the EPA from complying with the law, and cite Cement Kiln Recycling Coalition v. EPA, 

255 F.3d 855, 865 (D.C. Cir. 2001); “Even accepting the proposition that factors affecting source 

performance ... are difficult to quantify....If EPA cannot meet this requirement using the MACT 

methodology, it must devise a different approach capable of producing floors that satisfy the 

Clean Air Act.”

Response 3.2: Commenters assert that the EPA must account for malfunctions when 

determining the emissions level achieved by the best performing sources, but this view is neither 

reasonable nor supported by the text of the CAA. A 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 interprets CAA section 112 as not requiring emissions that occur during 

periods of malfunction to 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 section 112 that directs the Agency to consider 

malfunctions in determining the level “achieved” by the best performing sources when setting 

emission standards. As the D.C. Circuit 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). As discussed above, nothing in section 112 requires the 

Agency to consider malfunctions as part of that analysis, accounting for malfunctions in setting 

emission standards would be difficult, if not impossible, and could lead to standards that are not 

reflective of levels achieved by a well-performing non-malfunctioning source. Accordingly, the 

EPA’s approach to malfunctions is a reasonable interpretation of the statute. And in the event 

that a source fails to comply with the applicable CAA section 112 standards as a result of a 

malfunction event, as discussed above, the EPA would determine an appropriate response, and 

the source can raise any and all defenses in any enforcement action that may be filed.

The CAA also requires those standards to apply on a continuous basis, which the D.C. 

Circuit has interpreted to include periods of start-up, shut-down, and malfunction. See Sierra 

Club v. EPA, 551 F.3d at 1027-28 (striking down a general provision that exempted start-up, 

shut-down, and malfunction periods). The EPA’s approach both accounts for variability 

associated with a reasonably foreseeable range of operating conditions and recognizes that 

enforcement mechanisms can address emission exceedances due to unpreventable equipment or 

process failures. While commenters seek greater accommodation for malfunctions, such 

accommodation is not compelled by the statutory text and the EPA believes our approach is 
20

reasonable.

Unlike start-up and shut-down, which are foreseeable operations, no one can predict the 

nature, scope, severity, timing, length, number or likely recurrences of malfunctions a source 

may – or may not – experience. Although EPA bases emission standards on different manners of 

operations and circumstances, EPA only takes into account conditions that are “foreseeable” 

and “which can reasonably be expected to recur.” Sierra Club, 167 F.3d at 665; see also Nat. 

Lime, 627 F.2d. at 431, n.46. Virtually no malfunction is foreseeable in terms of its nature, 

timing or effect on emission levels and no operator knows if or when a malfunction could recur. 

Commenters identify no language in the statute that even implies that EPA must factor 

into MACT emission standards the emission levels that occur during malfunctions. Yet, they 

assert that CAA section 112 mandates that EPA account for malfunctions in establishing every 

single MACT floor standard or set a separate MACT floor standard for malfunctions, so that 

they reflect higher emission levels that might occur during undefined, unidentified malfunction 

events. Commenters appear to rely on the silence of section 112, which does not speak directly to 

how malfunctions are to be treated to support their view, filling the void with their own 

judgments of how EPA must address such uncertain and undefined events.

Where a statute is ambiguous or leaves a gap as to its application, the Court must defer 

to the agency's interpretation so long as it is “based on a permissible construction of the 

statute,” Chevron, 467 U.S. at 842-43, and in making this determination under the regulatory 

HAPs program administered by EPA, the Agency is accorded substantial deference. Although 

EPA may have authority to address malfunctions through different mechanisms – albeit limited 

by the Court in Sierra Club v. EPA (striking down exemptions for malfunctions) and NRDC v. 

EPA (striking down an affirmative defense for malfunctions) – EPA’s interpretation that it is not 

required by section 112 to address malfunction emissions by resetting MACT numeric standards 

is a rational application of section 112.

EPA has accounted for variability among the best performing sources’ emissions over the 

range of foreseeable operating conditions. But, as EPA determined, it would be impracticable 

for EPA to factor unforeseeable, random malfunction incidents into emission standards, and 

commenters offer no roadmap for doing so. 

In any event, there is no statutory basis for requiring EPA to take such action. 

Commenters assert that section 112 mandates that EPA establish MACT floor standards so that 

they reflect higher emission levels that might occur during unidentified, unmeasured malfunction 

events. To support their argument, the commenter states that emission limitations must be 

“achieved in practice,” which means that the EPA must show that at least one facility can meet 

the emissions limitations being promulgated (for new sources) and that a similar showing is 

required for existing sources. The commenter asserts that the EPA has failed to develop 

standards that are “achieved in practice” if even the best performing existing sources are 

expected to have malfunctions, and those malfunctions result in emissions that exceed the 

standard. But a source that suffers worker malfeasance or experiences a hurricane or a terrorist 

event, may also exceed emission standards at certain times. These events, like malfunctions, do 

not transform standards based on emission levels that actually have been achieved into 

unachievable standards. Indeed, under commenter’s reasoning, every MACT floor is forever 

invalid because it does not reflect emission levels that will occur during the next malfunction, act 

of God, strike, malfeasance or other unpredictable event.

Hurricanes and malfeasance can also occur at well-maintained and well-managed 

sources, but this does not warrant factoring such unpredictable events into emission standards. 
21

Even if malfunctions were inevitable for all sources, including the best-performing sources, that 

does not make it possible to take them into account when establishing MACT emission standards, 

because they are still unknown in frequency, length, magnitude and, most importantly, effect on 

emission levels.

The commenter (65) asserts that the EPA inappropriately relies on the CWA case 

Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) because the Weyerhaeuser 

court based its holding on the fact that the standards at issue there were technology-forcing. 

While the Court did address this point, it went on to uphold EPA’s case-by-case enforcement 

discretion approach to addressing malfunctions because interjecting factors dependent on 

“murky determinations concerning the sequence of events in the plant, whether those events 

would have been avoidable” and similar factors, is inconsistent with the intent of Congress to 

require numeric emission standards that are measurable and easily enforceable. 590 F.2d at 

1057-58. 

The commenters also offer the decision in Cement Kiln Recycling Coalition v. EPA as 

further proof that malfunctions must be considered in developing emissions standards. However, 

nothing in Cement Kiln even implies that EPA has a duty to reflect in its emission standards 

emission levels that might occur during unpredictable malfunction events. To the contrary, 

Cement Kiln cuts to the heart of commenters’ argument. The fundamental principle of 

commenters’ argument is that due to malfunctions, the MACT emission standards, which 

undeniably have been achieved by OSWRO facilities, may be “unachievable” if specific sources 

experience a malfunction. The Court in Cement Kiln, however, rejected the notion that because a 

MACT standard may not be achievable by some sources, it is invalid. Cement Kiln, 255 F.3d at 

861 (“EPA may not deviate from section 7412(d)(3)’s requirement that floors reflect what the 

best performers actually achieve by claiming that floors must be achievable by all sources using 

MACT technology.”). See also Sierra Club v. EPA, 479 F.3d at 878; NACWA, 734 F.3d at 1150 

(explaining that the argument that a MACT standard is invalid because it is not achievable by all 

sources at all times has been “roundly rejected” by the Court).

Comment 3.3: Commenter 65 urges the EPA to establish work practice standards for 

malfunctions as allowed in CAA section 112(h), in part because it is infeasible to gather data 

during malfunctions due to the lack of EPA approved test methods for non-steady-state 

conditions. The commenter notes that in the 2008 SSM decision, the court stated that the 

inclusion of “continuous” in the CAA definition of emission standard means that some standards 

apply at all times but does not mean that the same standard must apply at all times, and 

specifically noted the potential for the EPA to address malfunctions through work practice 

standards. As an example, the commenter suggests a requirement to implement a malfunction 

plan that would detail a facility’s response to malfunctions and that would outline a method to 

expeditiously return to allowable operating conditions. Commenter 61 suggests an approach where 

the EPA would gather data from the best performing sources on best practices used to mitigate 

excess emissions during malfunctions. The commenter also suggests that the EPA could create an 

emission standard that combines emission limits with work practice standards. 

Response 3.3: The EPA’s rationale for its approach to malfunctions is discussed in the 

preambles to the proposed rule and this final action. 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. CAA section 112 uses the concept of “best 

controlled” or “best performing” unit in defining the level of stringency that CAA section 112 

standards must meet. Applying the concept of “best controlled” or “best performing” to a unit 
22

that is malfunctioning presents significant difficulties, as malfunctions are sudden and 

unexpected events. Accounting for malfunctions would be difficult, if not impossible, given the 

myriad different types of malfunctions that can occur across all sources in the source category 

and given the difficulties associated with predicting or accounting for the frequency, degree, and 

duration of various malfunctions that might occur. Setting work practice standards under CAA 

section 112(h) for malfunctions – as opposed to startup or shutdown periods – presents the same 

issues as setting numerical emission limits given the varied nature of malfunctions.

The decision to use a work practice standard is wholly within the discretion of EPA. CAA 

section 112(h) (“[T]he Administrator may, in lieu [of a numeric standard], promulgate a design, 

equipment, work practice, or operational standard, or combination thereof.”). In exercising the 

option to establish a work practice standard, that standard must “in the Administrator’s 

judgment [be] consistent with the provisions of subsection (d) or (f).” CAA section 112(h)(1) 

(emphasis added). These subsections make clear that EPA is to base emission standards on the 

emission levels already achieved by the best performing sources and to ensure that public health 

is protected, as applicable. This means that work practice standards, although written in nonnumeric form, must still satisfy statutory requirements such as those applicable to MACT 

standards, including the requirement to be no less stringent than the MACT floor.

It is just as difficult to establish a work practice standard for malfunctions that can 

approximate the level of emission reduction achieved by the best performing sources during 

malfunctions as it would be to factor emission levels that occur during malfunctions into the 

numeric standards, as discussed above. EPA would have to design a single work practice 

standard that applies equally to a tank explosion as it does to innumerable types of operator 

error, computer glitches or a myriad of other unknown events, or alternatively create 

innumerable work practice standards.

The commenter’s generic suggestion to create a work practice standard that merely 

directs sources to have plans to respond to malfunctions and expeditiously return to compliant 

operating conditions does not present a viable solution. The commenter has not provided any 

evidence that a mere requirement to have such a plan is consistent with EPA’s obligation under 

section 112(h) to establish a work practice standard only if, in the Administrator’s judgment, it is 

consistent with section 112(d) including the MACT floor requirement. In sum, EPA believes that 

based on this rulemaking record it would be clearly inappropriate to set a work practice 

standard for malfunctions in lieu of the otherwise applicable numerical emission limit. We also 

note that we would consider any response to violations caused by a malfunction on a case-bycase basis through the exercise of enforcement discretion.

Comment 3.4: Commenter 63 states that the past history of the SSM exemption and 

compliance problems for the source category demonstrates a need for strong and more frequent 

monitoring, testing, and reporting requirements and enforcement provisions. The commenter 

declares that the EPA must implement enforcement provisions that prevent and remedy emission 

spikes, malfunctions, and other violations in a way that will be enforceable by citizens in the 

Title V permits for this source category. The commenter further states that the EPA should 

review the proposed monitoring requirements and ensure they are stringent enough to enable 

easy assessment of whether a facility is in full compliance with the standards within a short 

period of time of any violation.

Response 3.4: We believe that the removal of the SSM exemption will reduce compliance 

problems that may have been associated with the exemption and excess emission spikes, as 
23

facilities have an incentive to avoid the related violations and penalties, without the need to 

institute more frequent monitoring, testing, and reporting requirements. We further believe that 

the monitoring requirements included in these rules are sufficient to ensure compliance with the 

standards regardless of whether or when a violation occurs. Under the provisions of 40 CFR 

63.15, the public can request access to reports submitted to the regulatory agency whenever they 

choose, with the exception of information protected through 40 CFR part 2 (e.g., confidential 

business information). In addition, as discussed in section 4.0 below, we are promulgating 

requirements for electronic reporting of emissions test data that will improve public access to 

emissions information.

Comment 3.5: Commenter 63 states that additional requirements are needed for times of 

malfunctions, including requirements for automatic shut-off of malfunctioning equipment, 

requirements to assign responsibility to the plant manager or high-up staff member which allows 

only that person to restart the equipment, and requirements that corrective actions be taken 

immediately. The commenter also states that for a facility that has had one or more malfunction, 

exceedance, or other violation in the prior month, the facility must obtain written authorization 

from the EPA to restart the equipment, and the EPA should only authorize the restart after 

making a public determination that the facility has instituted the corrective measures the EPA 

requires. The commenter further asserts that for a facility with more than 4 exceedances or 

malfunctions in the same quarter, the EPA must require automatic shutdown of the operation for 

a period of time to conduct and publish a full investigation and ensure correction of the 

problem(s).

Response 3.5: We disagree with the commenter that the suggested additional 

requirements regarding malfunctions or violations are necessary. The EPA believes that the 

monitoring requirements of the final rule are sufficient to ensure compliance with the emission 

standards, and that it is not necessary to prescribe when or who may restart equipment that has 

malfunctioned. 

Comment 3.6: Commenter 63 supports EPA’s proposal to require specific public 

reporting of malfunctions, but expresses concern that EPA proposes to require malfunction 

reporting as part of a periodic compliance report. The commenter states that the EPA should 

require safety-related reports and notification much sooner to protect populations living near the 

facility. Specifically, the commenter declares that the EPA must require telephone reporting by 

the facility 24 hours of a malfunction or exceedance and make a notice available publicly

through the EPA’s website and through ECHO within 24 hours. The commenter also asserts that 

within 24 hours of receiving this notification, the EPA should provide this information to the 

appropriate EPA Regional Office and direct the Regional Office to notify the local community of 

the event on the Internet, direct communication, and through all available means. The commenter 

states that the EPA should further require the facility to provide notification to the community

through an appropriate public forum, including the company website, written notice to the local 

municipality and local school district, and press release to the local newspaper, radio and TV 

news station, within 24 hours, that contains any information community members may need to 

try to protect themselves and their families from the additional air pollution. The commenter 

further declares a written report should be required within 7 days and distributed to the public 

using the same distribution method as the earlier notification and that this report should include 

the nature of the event, the duration of the event, estimate of emissions released during the event, 
24

and a description and time of corrective actions taken and planned to be taken.

Response 3.6: As noted by the commenter, the final rule requires malfunction 

recordkeeping and reporting, including for each failure to meet a standard, the date, time, and 

duration, a list of the affected sources or equipment, an estimate of the volume of each regulated 

pollutant emitted over the standard, a description of the method used to estimate such emissions, 

and actions taken to minimize emissions and any corrective actions taken. Any reports submitted 

to the EPA are publicly available subject to the requirements of CAA section 114(c). We do not 

agree with the commenter that the suggested additional notification and reporting requirements are 

necessary, as they would be duplicative of the immediate notification requirements of 

SARA/CERCLA/EPCRA, would be burdensome for both facilities and agencies to review, and would 

not enhance compliance beyond that of the requirements in the rule for reporting violations of 

emission limits. 

Comment 3.7: Commenter 63 states that the EPA is legally required to remove all 

unlawful exemptions from the emission standards that have previously existed for startup, 

shutdown, and malfunction (SSM) periods, and not to set any new such exemptions. The 

commenter claims that equipment leaks are a kind of equipment malfunction and that EPA may

not authorize any such leaks, because to do so would be in violation of CAA section 302(k) and 

D.C. Circuit precedent in the Sierra Club v. EPA decision. The commenter also stated that EPA’s 

proposal to not update the leak detection and repair (LDAR) requirements is an unlawful 

authorization of a malfunction exemption.

Response 3.7: We disagree with the commenter’s claim that the types of equipment leaks 

addressed in the OSWRO NESHAP are “malfunctions.” Equipment leaks typically occur from 

equipment such as pumps, compressors, agitators, pressure relief devices, sampling collection 

systems, open-ended valves or lines, valves, and connectors. 40 CFR 63.691; See also 61 FR 

34147 (July 1, 1996). At the time we developed the MACT standards for this source category, we 

recognized that these emission points regularly emit small quantities of HAP, and we 

promulgated standards regulating equipment leaks from these components at 40 CFR 63.691. 

These provisions require OSWRO facilities to monitor for leaks and to repair any detected leaks. 

These requirements do not establish any exemption, and the commenter’s suggestion that leaks 

are “exempt” from regulation or that they are “authorized” is not supported. While any specific 

equipment leak is not predictable, the types of equipment leaks addressed by the regulations at 

40 CFR 63.691 are fairly routine emissions from sources and are not the type of unpredictable 

or infrequent event for which we cannot anticipate when, where or how they may occur and that 

we generally consider to be malfunctions.

4.0 Electronic Reporting Requirements

Comment 4.1: Commenter 58 states that the EPA should address technical issues with 

the Electronic Reporting Tool (ERT) before requiring submittal of performance test information 

using the ERT. Based on their experience, the commenter provided examples of technical issues 

with the ERT primarily related to the need to submit “default/fake” data in order to make the 

system work.

Response 4.1: We thank the commenter for the input about situations in which the ERT 

may require some revisions and the commenter’s experience working with EPA contacts 

regarding data submission. We believe the benefits of the system articulated in the proposal 

preamble outweigh the minor technical issues that may arise during its use, and that a delay in 
25

the implementation of the system for these issues is not warranted. We note that we are working 

to continually update and improve the system to address technical issues such as those noted by 

the commenter.

Comment 4.2: Commenter 61 comments that the proposal to require the use of the ERT 

is not appropriate as the costs and burdens imposed cannot yet be determined. Also, the regulated 

community cannot fully comment on the cost of duplicating reports using the ERT for Method 

18 and other methods not currently supported by the ERT. The commenter states that the EPA 

should ensure the ERT includes the ability to accommodate all of the required test data, 

including Method 18, which can be quite voluminous.

Response 4.2: The rule only requires that test methods supported by the ERT be reported 

using the ERT. The EPA believes that the costs and burdens of using the ERT are not significant 

for several reasons. The electronic reporting requirement does not add any additional testing 

and it does not change the timing of when test reports are due: the requirement only states that 

reports be submitted electronically. The ERT is fully functional, has been used successfully by 

industry for several years, was designed to capture all of the information which is submitted in a 

typical test report, and was also designed with input from States and the stack testing industry.

Comment 4.3: Commenter 61 notes that without a formal notice that changes are being 

made to the ERT, facilities are at risk of noncompliance with the ERT requirements because they 

have no way to know which test methods must be submitted to ERT unless they actively monitor 

the EPA’s web site. 

Response 4.3: The ERT website is kept up-to-date with the list of methods that are 

supported by the ERT. The ERT versions after September 17, 2012 automatically check for 

updated versions and notify the user of the need to replace the ERT application. Additionally, if 

the facilities wish, the EPA recommends joining the CHIEF listserv, which one can do by 

emailing join-chief@lists.epa.gov, to be notified of enhancements made to the ERT. Additionally, 

the test method dropdown box in the ERT contains a finite list of methods supported by the ERT. 

By using the latest version of the ERT, the facility will know from the dropdown box which 

methods are supported.

Comment 4.4: Commenter 61 comments that under the proposed rule 40 CFR 

63.697(a)(3)(i), all performance test reports must be submitted to the ERT within 60 days, but 

because the rule does not reference the general provisions 40 CFR 63.10(d)(2), there is no 

allowance for obtaining additional time to complete this due to unforeseen circumstances or for 

the difficulties involved with completing particularly complex reports.

Response 4.4: The commenter is incorrect that 40 CFR 63.10(d)(2) is not currently 

applicable to Part 63 Subpart DD. Table 2 to Subpart DD clearly indicates that 63.10(d)(2) 

applies to Subpart DD. The Administrator may approve additional time for a facility to submit 

the results of its performance tests as allowed under 40 CFR 63.10(d)(2); however, the EPA does 

not anticipate that additional time will be needed for facilities to submit performance tests due to 

the requirement to use the ERT, as the ERT is fully functional and has been used successfully by 

industry for several years. 
26

5.0 Equipment Leak Provisions

5.1 Open Ended Line Provisions

Comment 5.1.1: Commenter 58 commented that although the proposed language 

requires “no instrument reading of 500 parts per million or greater,” there is not a proposed 

requirement to monitor the cap, blind flange, plug or second valve. The commenter adds that 

these components are not usually in regulated material service if there is a closed valve upstream, 

and therefore regulated sources would not typically monitor these components. 

Response 5.1.1: Open-ended lines and valves are equipment which require the proper 

installation and use of caps, blind flanges, plugs and second valves to seal the OEL to prevent 

leaks. However, the EPA does agree with the commenter that monitoring of OELs is not 

currently required by the LDAR provisions of the OSWRO NESHAP.

Comment 5.1.2: Commenters (60 and 61) state that while there are no proposed 

monitoring requirements in the rule, facilities will need to establish their own monitoring 

program and schedule for OELs without any assurance that their individual program or schedule 

would be considered to be in compliance by an EPA inspector. Commenter 58 adds that if the 

intent is to require routine monitoring of these components, rule changes are needed to add time 

periods for completion of repairs. Commenters (58 and 61) contend that if the EPA does intend 

to require periodic monitoring, such monitoring rules must be clearly proposed in a second 

rulemaking with a public comment period. Commenter 61 states that the EPA did not develop 

any cost estimates or impacts on the regulated community resulting from the proposed definition 

of “seal.” However, the commenter states that facilities will need to develop monitoring plans 

and regularly monitor OEL seals to ensure they have instrument readings below 500 ppm, which 

will require capital costs including identifying, tagging and updating software systems for OEL 

seals. 

Response 5.1.2: The EPA is not imposing monitoring requirements for OELs. There are 

no additional costs associated with the clarification concerning “sealed” OEL. We also disagree 

with the commenters that the EPA is requiring facilities to regularly monitor their OELs, and 

thus incur capital and annual costs. The requirement that OELs be sealed is not a new standard 

and there is no requirement in any of the LDAR requirements for this source category that 

requires facilities to monitor their OELs on a regular basis. 

Comment 5.1.3: Commenter 61 notes that if the EPA revises the definition of “seal” for 

the OSWRO NESHAP, then it will also need to propose changes to subpart H at 40 CFR 63.167 

to include the proposed emission limit of 500 ppm for OELs. The commenter adds that the EPA 

must update Method 21 to account for accurate OEL monitoring.

Response 5.1.3: It was the EPA’s intent that the clarification of the term “seal” would 

apply to all OELs in off-site material service, regardless of whether the facility complies with the 

LDAR requirements in 40 CFR part 63, subpart H or 40 CFR part 61, subpart V. As such, we 

have revised the equipment leak requirements in 40 CFR 63.691(b)(1)(iii) and (iv) to clarify that 

the term “seal” applies to OSWRO facilities complying with either subpart H or subpart V. 
27

With regard to the commenter’s suggestion to update Method 21, we note that Method 21 

states that it is “applicable for the determination of VOC leaks from process equipment” and 

lists several examples of equipment comparable to OELs, in terms of potential sources of 

equipment leaks, which can be monitored with the method. In fact, sections 8.3.1 and 8.3.1.6 of 

the method describe how to take a sample from an open-ended line or valve. The final OSWRO 

rule does not impose monitoring requirements for OELs; however, if a facility chooses to 

monitor OELs, Method 21 is an appropriate monitoring method for those devices, and there is 

no need to amend it for this purpose. 40 CFR 63.8(f) is also available for a facility owner or 

operator seeking approval of a modification to a monitoring method

5.2 Pressure Relief Device Provisions

Comment 5.2.1: Commenter 58 states that the proposed monitoring requirements for 

PRDs should not be applied to containers because they would not be practical to implement, 

considering that containers are portable, are moved frequently, and are received from a number 

of off-site locations. 

Response 5.2.1: We believe the PRD monitoring requirements are necessary for all 

PRDs to enable operators to identify and minimize emissions from pressure release events. We 

note that many OSWRO containers do not have PRDs and that, by definition, devices that are 

actuated either by a pressure of less than or equal to 2.5 pounds per square inch gauge (psig) or 

by a vacuum are not PRDs.

Comment 5.2.2: Commenter 58 states that the EPA should continue to include parameter 

monitoring systems as options for PRD monitoring systems, but should add specific examples of 

parameter monitoring systems in the rule language, such as a flow monitor or pressure monitor, 

to the examples of applicable PRD monitoring systems in 40 CFR 63.691(c)(3)(i). 

Response 5.2.2: We agree with the commenter that examples of parameter monitoring 

systems could be provided in addition to the direct monitoring device examples listed in the 

proposed language, and we have revised the final rule accordingly to improve the clarity of the 

PRD monitoring requirements.

Comment 5.2.3: Commenters (61, 64, 67) dispute the EPA’s analysis of the costs to 

comply with PRD monitoring requirements. Commenter 61 asserts that a legally required 

parametric monitoring system imposes burdens that the industry does not incur for a parametric 

monitoring system that is installed for process control, such as data quality evaluation and 

reporting efforts. Commenter 67 states that the EPA underestimated the costs of installing 

monitoring devices on PRDs. The commenter disagrees with the use of the “six-tenths rule” to 

account for economies of scale, and states that any actual economies of scale would depend on 

regional cost factors and overall demand for the product. The commenter states that the EPA 

justifies the use of the six-tenths rule based on a reference to the 2007 South Coast Air Quality

Management District (SCAQMD) Final report; however, the SCAQMD does not mention the 

six-tenths rule and only makes a general reference to economies of scale. Commenter 64 states 

that the costs of implementing the proposed amendments are significantly greater than the EPA’s 

estimate and that the EPA’s cost analysis did not include costs for purchasing, installing, and 

maintaining PRD monitoring devices or the costs associated with designing, constructing and 

maintaining a closed vent system and control device..
28

Further, the commenter states that based on a web search they have been unsuccessful in 

finding any currently available monitoring devices for PRDs that would satisfy the requirements 

of the proposed amendments, and expresses concern that there is an unknown cost for obtaining, 

operating, and maintaining PRD indicator devices. The commenter states that PRD monitoring 

devices are not currently used at OSWRO facilities and the availability, reliability and accuracy

of these devices is unknown.

Response 5.2.3: The EPA disagrees that PRD monitoring costs have been 

underestimated. The estimated costs to purchase and install PRD monitors were based on the 

best information available, which was data from the SCAQMD, and the costs considered 

included the cost to purchase the device, and installation and maintenance costs. We also 

accounted for the costs associated with recordkeeping and reporting of PRD data in the analyses 

for the information collection request for this rulemaking. As the rule does not require PRDs to 

be vented to a control device, no costs associated with doing so were included. In addition, we 

note that costs were adjusted to account for economies of scale using the six-tenths rule, which is 

a general cost estimating technique that has long been used by engineers in industries with 

processes similar to those regulated by the OSWRO NESHAP, such as the chemical and 

petroleum industries. More information about the six-tenths rule can be found in engineering 

and industrial cost estimation literature. Furthermore, as an owner or operator may be able to

use parameter monitoring systems already in place, we believe our cost estimate, which assumed

the installation of electronic indicators on each relief device that vents to the atmosphere, likely 

overstates actual costs to the industry. Several types of electronic monitoring devices that could 

be used for PRDs were discussed in the 2007 SCAQMD Final Report referenced and made 

available with the proposed rule in the memorandum entitled Cost Impacts of Pressure Relief 

Device Monitoring for the Off-site Waste and Recovery Operations Source Category, available 

in the docket for this action. Also, these devices have been required for refineries in the 

SCAQMD since 2009, and we are not aware of any issues with availability, reliability or 

accuracy of the devices used.

Comment 5.2.4: Commenter 61 cites the EPA’s statements that PRD releases are caused 

by malfunctions and that the EPA is not required to establish separate standards for malfunctions 

and it is too difficult to do so. The commenter asserts that a PRD release is unique in that the 

“release” is an inherent function of the device, and therefore a work practice standard or a 

numerical emissions limit could be established. The commenter believes the EPA could have 

considered data submitted by the commenter along with available data to determine whether it 

may be feasible to group PRDs with process vents and propose a numerical emission standard 

under CAA section 112(d)(3). Alternatively, the commenter states the EPA could have 

established a work practice standard for PRD releases pursuant to its authority under CAA 

section 112(h). The commenter urges the EPA to consider either of these approaches. Similarly, 

commenter 69 advises the EPA to set work practice standards under the authority of CAA 

section 112(h), instead of establishing a numeric standard under CAA section 112(d).

Response 5.2.4: We disagree with the commenters. The releases are related to process 

upsets or other malfunctions that require the release of pressure to avoid damage to equipment 

and to prevent harm to personnel at the facility. Such releases at OSWRO facilities are not 

routine, are unpredictable in nature, and are considered to be caused by malfunctions (e.g., poor 

design, improper maintenance, or operational error) or other occurrences that do not justify an 

exemption from standards that, under the CAA, apply continuously. The commenter has also 
29

failed to establish that the criteria for setting a work practice had been met, and as we explained 

in the preamble, it is impracticable to establish work practices or other alternative standards to 

manage these events in this source category, and CAA section 112 does not require that we do 

so.

Comment 5.2.5: Commenter 58 suggests that the EPA clarify throughout the final rule 

that opening of a safety device is acceptable to prevent physical damage or permanent 

deformation of equipment. The commenter states that the EPA should not remove the option to 

comply with the provisions that allow for opening of a safety device to avoid an unsafe condition 

from the requirements for tanks, containers and transfer systems. The commenter suggests 

revisions to the requirements for tanks, containers, transfer systems, and PRD to clarify that a 

release from a safety device to prevent unsafe conditions is acceptable, and to record such 

releases and identify them as a deviation in the next Title V report. The commenter argues that 

ASME Section 8 Division 1 and 2 and API #620 and 650 vessel construction codes, DOT 

regulations such as in 49 CFR 178 and 179, and ASME/ANSI piping codes require that PRD 

operate when the maximum allowable working pressure is reached for tanks, containers and 

transfer systems, respectively. The commenter further states that the definition of “safety device” 

should not be deleted from 40 CFR 63.681. 

Response 5.2.5: We disagree with the commenter that the definition of “safety device” 

should not be deleted from the OSWRO NESHAP and that releases from such devices to the 

atmosphere should be allowed. As stated in the preamble to the proposed rule, “To our 

knowledge, pressure relief devices or valves are the only safety devices used in OSWRO 

processes.” The commenter has not provided any information to suggest there are safety devices 

at OSWRO facilities that are not PRDs. Further, as explained in the preamble to the proposed 

and final rule, we are finalizing the proposed prohibition of HAP emission releases to the 

atmosphere from PRDs in off-site material gas or vapor service in order for our treatment of 

malfunction-caused pressure releases to the atmosphere to conform with the reasoning of the 

Court’s 2008 Sierra Club v. EPA ruling.

Comment 5.2.6: Commenter 64 states that the installation of monitoring devices on 

PRDs and the venting of PRDs to a control device would require a modification to their 

Hazardous Waste and Title V operating permits, and requests a transition period to allow a 

currently operating facility to obtain a permit modification prior to the effective date of the new 

standard.

Response 5.2.6: The final rule requires that PRDs be monitored, unless they are vented 

to a control device, within three years of the publication date of the rule. We believe this amount 

of time is adequate to allow facilities to research equipment and vendors, and to purchase, 

install, test and properly operate any necessary equipment. We also believe that three years is an 

ample amount of time to accomplish any necessary permit revisions. In addition, we note that 

facilities must be in compliance with the new requirements by the compliance date, regardless of 

whether the operating permit has been updated by that date.

5.3 Compliance with 40 CFR Part 63 Subpart H, Including Connector 

Monitoring Provisions

Comment 5.3.1: Commenter 61 notes that contrary to the preamble, which states that the 
30

EPA is proposing to eliminate the option of complying with 40 CFR part 61 subpart V and 

require facilities to comply with 40 CFR part 63 subpart H, the actual proposed revisions to the 

rule text in 40 CFR 63.691(b) continue to allow compliance with subpart V. 

Response 5.3.1: The EPA agrees with the commenter and we have corrected this 

inadvertent error by revising the regulatory text to eliminate the option to comply with 40 CFR 

part 61 subpart V. 

6.0 Tank Provisions

Comment 6.1: Commenter 66 supports the EPA’s conclusion that tank control 

requirements under Option 2 (98 percent control) are not cost effective and that the existing HAP 

control Option 1 (95 percent control) should remain in place for the tanks already subject to this 

control level. 

Response 6.1: We acknowledge the commenter’s support for the existing 95 percent 

control requirement for level 2 tanks, and agree that 98 percent control was not determined to be 

cost effective. 

Comment 6.2: Commenter 66 states that the EPA underestimated the number of

facilities that would be affected by the proposed amendments to the vapor pressure thresholds for 

tank control level. The commenter states that based on its member facilities, there are at least 34 

tanks at six facilities that would be impacted by the proposed amendments, and a significant 

number of facilities that are not associated with the commenter that would also be affected. The 

commenter also believes there are a significant number of facilities that are near the major source 

threshold that may become subject to the OSWRO MACT if they expand or change the types of 

materials they manage, and the EPA should consider these facilities in its impacts analysis.

Response 6.2: The commenter did not provide sufficient information to support the claim 

that we underestimated the number of tanks or facilities in our analysis. In addition, we note that 

CAA section 114 questionnaires were sent to several of the commenter's member companies in 

2013, and the responses received from them documented each OSWRO tank at each facility, with 

its size and the average vapor pressure of the tank contents. These data showed that none of the

commenter's member responding companies had uncontrolled tanks of the size and vapor 

pressure range that would be impacted by the tank standards. The commenter also did not 

provide documentation to support the claim that there are tanks at other facilities that would be 

affected by the tank standards nor the claim that there is a planned or impending change in 

status at any facility that would result in that facility becoming a major source subject to the 

OSWRO NESHAP. Therefore, we have not revised our analysis to include additional tanks or 

facilities. 

7.0 Control Device, Performance Testing, and Monitoring 

Provisions

Comment 7.1: Commenter 63 states that the EPA has not adequately supported the 

conclusion that bypass of control devices during maintenance for up to 240 hours per year should 

be allowed. The commenter notes the EPA’s statement that degassing the tank would release 

nearly all of the pollution coming from the tank. 
31

Response 7.1: As noted in the preamble to the proposed rule at 79 FR 37877, the existing 

OSWRO NESHAP at 63.693(b)(3)(i) allowed control devices to be bypassed for routine 

maintenance for up to 240 hours per year, under certain conditions. This existing provision was 

not limited to control devices for tank emissions. In this rulemaking, we proposed to limit the 

applicability of the provision to tanks routing emissions to a control device, consistent with the

rationale provided in the Hazardous Organic NESHAP (HON). We did not reopen the existing 

provision for comment, other than to propose limiting it to tanks. The commenter did not state 

any opposition to our limiting the provision to tanks, and we are finalizing it as proposed. We 

note that without this provision, facilities would instead need to degas the tank to conduct 

routine maintenance. The HAP emissions that would result from degassing the tank would be 

greater than the emissions that would result from the tank with its emissions bypassing a control 

device for a short period of time during routine maintenance. Other than paraphrasing a 

statement from the preamble, the commenter did not make any objections to EPA’s analysis. 

Therefore, we are finalizing the limitation on the routine maintenance provision in the OSWRO 

NESHAP to apply only to tanks routing emissions to a control device, consistent with the 

rationale provided in the HON.

Comment 7.2: Commenter 65 requests that EPA include container repackaging 

emissions in the 240 hour routine maintenance exemption to bypass a control device in 40 CFR 

693(b)(3)(i). The commenter asserts that emissions from these operations are not significant (less 

than 200 pounds VOC per year at one member facility) and operational/revenue losses would be 

greater than any environmental benefit. 

Response 7.2: The EPA disagrees that container repackaging operations should be 

included in the 240 hour routine maintenance provision. As noted in the preamble to the 

proposed rule in 79 FR 37811, we have not identified a basis for applying the routine 

maintenance provision in the OSWRO NESHAP to emission points other than tanks. We did not 

conclude that emissions during routine maintenance are “not significant.” Rather, we stated that 

HAP emissions that would result from degassing the tank would be greater than the emissions 

that would result from the tank with its emissions bypassing a control device for a short period of 

time during routine maintenance. Note that for storage tanks, it is impossible to “not operate” 

(i.e., “shutdown” as provided in 63.693(b)(3)(i) so as not to have breathing losses) during a 

period of time in which a control device would be undergoing routine maintenance, unless the 

tank is emptied and degassed. In contrast, container repackaging operations can be scheduled or 

delayed until such time as the routine maintenance is completed and the control device is again 

operating.

Comment 7.3: Commenter 64 requests clarification on the OSWRO applicability of 

hazardous waste incineration units that are already subject to the Hazardous Waste Combustor 

NESHAP (40 CFR part 63 subpart EEE). The commenter references the EPA’s discussion in the 

preamble related to distinguishing OSWRO from other source categories (79 FR 37852), and 

suggests that the OSWRO NESHAP does not apply to hazardous waste incinerators as these 

units are already regulated by a separate NESHAP.

Commenter 58 states that the EPA should add to the proposed OSWRO requirements in 

40 CFR 63.684(b)(5)(v) and 40 CFR 63.693(g)(1)(v) the option to comply with 40 CFR 63 

Subpart DDDDD (Boilers and Process Heaters NESHAP) when burning natural gas and/or nonhazardous waste.
32

Response 7.3: The EPA notes that the off-site material treatment standards for 

incinerators in 40 CFR 63.684(b)(5) do not include additional requirements pertaining to the 

operation of incinerators, but rather requires that if an incinerator will be used to comply with 

the OSWRO NESHAP, it must meet the requirements of one of the regulations listed in that 

paragraph. As part of this rulemaking, we have updated the list of regulations to include 

incinerators, boilers or industrial furnaces for which the owner or operator complies with the 

requirements of 40 CFR part 63 subpart EEE.

The EPA disagrees that the Subpart DDDDD Boilers and Process Heaters NESHAP 

should be a compliance option in the control device provisions for boilers and process heaters or 

the offsite material treatment provisions for incinerators in the OSWRO NESHAP. These 

OSWRO provisions require compliance with the RCRA requirements for incinerators in 40 CFR 

part 264, part 265 or part 266 or with the option we are adding in this action to comply with 40 

CFR part 63, subpart EEE. The subpart EEE and RCRA standards specify requirements for units 

that combust hazardous waste as defined in 40 CFR 261.3, and are therefore appropriate for the 

OSWRO NESHAP, which regulates the management and treatment of certain types of waste that 

contain HAP, including many types of waste classified as hazardous. The Boilers and Process 

Heaters NESHAP does not apply to a unit that burns hazardous waste (unless the unit is exempt 

from subpart EEE). We believe this standard would also be insufficient for units that burn nonhazardous off-site materials, as such materials are likely to be more toxic than the types of 

materials burned in incinerators regulated by the Boiler and Process Heaters NESHAP. In 

addition, a provision allowing for the use of separate requirements for units that only burn nonhazardous offsite materials or allowing for separate requirements only at times when the unit is 

burning non-off-site or non-hazardous materials (e.g., natural gas), would make the 

requirements of the OSWRO NESHAP difficult to implement and impractical to enforce,

especially considering the myriad types of wastes regulated by the NESHAP. 

Comment 7.4: Commenters (58 and 61) state that the EPA should include “high point 

bleeds” in the list of equipment in 40 CFR 63.693(c)(2)(iii) that is exempt from the requirement 

to install flow indicators or seals or locking devices on control device bypass lines. The 

commenters assert that high point bleeds may be necessary on an intermittent basis to alleviate a 

potential flow restriction and safety concern. Further, both commenters state that open-ended 

valves and lines in emergency shutdown systems should be exempt from the flow indicator or 

seal or locking device requirements because the valve must quickly change position if an 

unexpected shutdown occurs, and a seal or locking device would prevent this movement. 

Response 7.4: As stated in the preamble to the proposed rule in 79 FR 37878, we are 

prohibiting bypasses that divert a process vent or closed vent system stream to the atmosphere to 

ensure the OSWRO NESHAP is consistent with the 2008 Sierra Club v. EPA ruling., A discharge 

of HAP to the atmosphere from a high point bleed is considered a bypass that is a deviation, as 

provided in 40 CFR 63.683(f)(4)(ii). Bypass devices are required to be equipped with either a 

flow indicator or a seal or locking device, and are subject to the recordkeeping and reporting 

requirements in 40 CFR 63.696(j)(2) and 40 CFR 63.697(b)(6). 

We are also requiring that open-ended valves and lines in emergency shutdown systems 

follow the requirements for bypass devices that could be used to divert a vent stream from the 

closed-vent system to the atmosphere. If a seal or locking device cannot be installed on such 

bypass devices, as suggested by the commenter, the owner or operator can alternatively install a 

flow indicator, which does not restrict the valve from quickly changing position, and must keep 
33

records of each release and report any deviations as specified in the proposed standard. 

Comment 7.5: Commenter 58 states that the proposed requirement for control device 

performance tests in 40 CFR 63.694(l) to “include in such record an explanation to support that 

such conditions represent normal operation” is redundant to the requirement that performance 

tests “shall be conducted under such conditions as the Administrator specifies to the owner or 

operator based on representative performance of the affected source for the period being tested”

and will require additional agency action in approving a performance test plan. The commenter 

suggests that the EPA delete the phrase that states the Administrator will specify performance 

test conditions. 

Response 7.5: The EPA agrees with the commenter, and the final rule has been revised to 

more simply indicate that performance tests must be conducted under conditions of normal 

operation. 

Comment 7.6: Commenter 58 requests that the EPA allow for unusual circumstances 

during performance tests where limitations of the equipment or plant operation prevent the test 

from being completed. The commenter suggests adding the sentence “Exceptions to this may be 

approved on a case by case basis and should be approved during a pretest meeting or prior to the 

actual compliance testing” after each paragraph that specifies minimum testing requirements, 

including 40 CFR 63.694(f)(1), (i)(1), (l)(3)(i), (l)(4)(i) and (m)(4)(ii)(A). 

Response 7.6: The EPA disagrees that the language suggested by the commenter should 

be included in the OSWRO NESHAP test method requirements. The performance test notification 

requirements of 40 CFR 63.7 provide a notification and approval process for the instances 

mentioned by the commenter. In addition to the reference to 40 CFR 63.7 contained in 40 CFR 

63.697(b)(1), we have corrected an error in the General Provisions applicability table, Table 2 

to subpart DD, to indicate clearly that the provisions of 40 CFR 63.7(b) and (c) and 40 CFR 

63.9(e), which are the performance test notification requirements, apply for subpart DD. The 

performance test notification requirements in 40 CFR 63.7, require that the source notify the 

Administrator 60 days before the date of the performance test to allow the Administrator, upon 

request, to review and approve a site-specific test plan, and the Administrator has 30 days to 

approve or deny this site-specific test plan. In the event that there are unusual circumstances that 

prevent the specified performance test methods and procedures required by the OSWRO 

NESHAP from being undertaken, as suggested by the commenter, any such differences should be 

submitted in the site specific test plan for approval by the Administrator. 

Comment 7.7: Commenter 57 states that in the semiannual reporting requirements for 

control device monitoring deviations in 40 CFR 63.697(b)(4), the EPA mistakenly omitted a 

reference to 40 CFR 63.683(f), which identifies additional proposed deviations.

Response 7.7: The EPA has corrected the identified error in the final rule.

8.0 Other Comments

Comment 8.1: Commenters (59, 63) support the EPA’s proposal of additional measures, 

including more stringent provisions for certain tanks and more stringent LDAR requirements. 

Commenter 59 encourages EPA to include these additional provisions in the final rule.
34

Commenter 63 further supports the EPA’s actions to collect additional emissions and pollution 

control data for the OSWRO source category, remove SSM emissions exemptions, prohibit 

releases of emissions from PRD, clarify the definition of seal, and add PRD monitoring 

requirements.

Response 8.1: We acknowledge the commenters’ support for the EPA’s proposed rule 

requirements.

Comment 8.2: Commenter 58 requests that the EPA allow OSWRO facilities that in the 

past accepted but are not currently accepting off-site waste a one year period to implement the 

provisions of the final rule from the date that they again accept off-site waste. The commenter 

states that the one year extension should apply to facilities (the commenter has one such facility) 

that begin accepting off-site waste again after the compliance dates for the new requirements 

(i.e., 2016 for LDAR requirements, 2017 for tanks, and 2018 for PRD monitoring). The 

commenter argues that this provision would allow the facility to incorporate the new compliance 

requirements into their planning to again receive off-site waste and would align with the 

flexibility provided in the MACT rules that allow for a one year compliance extension.

Response 8.2: The EPA disagrees with the commenter that a one year compliance 

extension should be provided in the rule for OSWRO facilities that currently are not but will 

begin receiving offsite waste again after the compliance dates for the new requirements. We are 

uncertain what the commenter means in alluding to unspecified MACT rules that supposedly 

provide for such flexibility. The General Provisions, as referenced by the OSWRO NESHAP in 

Table 2 to subpart DD of part 63, allow a facility owner or operator to apply for a one year 

compliance extension for the installation of controls under 40 CFR 63.6(i)(4)(i)(A). We note that

the commenter’s submission does not demonstrate that an additional year beyond the 

compliance dates provided in the rule is necessary for any OSWRO facility to comply with the 

revised standards in these situations. 

Comment 8.3: Commenter 58 recommends that the EPA clarify the applicability

language in 40 CFR 63.680(g)(1) to exclude facilities from complying with OSWRO 

requirements when the facility is not in off-site material service. The commenter also requests 

that the EPA revise the applicability of the language that identifies control device deviations as a 

violation in §63.695(e)(5) to exclude facilities that are not in OSWRO off-site material service. 

The commenter states that it has a facility that receives off-site waste infrequently and is used as 

a backup facility in case the primary facilities that receive off-site waste experience an unplanned 

shutdown. The commenter states that the facility would be subject to RCRA Subpart BB and CC 

regulations and would continue to comply with RCRA air permit conditions during these 

operating scenarios. 

Response 8.3: The EPA disagrees with the commenter that affected sources or portions 

of sources should be excluded from OSWRO emission limitations during periods that they are 

not managing off-site waste. We believe that such a provision would make the requirements of 

the NESHAP difficult for facility personnel to implement and would limit the ability of 

enforcement and compliance personnel to ensure that the maximum achievable emission 

reductions required by the standards are achieved and maintained. Such a provision would make 

the standard especially difficult to implement and enforce in instances where the source receives 

and manages both on-site and off-site material. In such cases, compliance and facility personnel 

would have difficulty in the determination of when the OSWRO NESHAP would and would not 
35

apply and which equipment would be subject to its requirements. 

Comment 8.4: Commenter 58 states that there is an incorrect reference in 40 CFR 

63.685(c)(2)(iii)(B); the reference to 40 CFR part 67 subpart OO should be 40 CFR part 63

subpart OO. The commenter also states that in 40 CFR 63.683 (c)(1)(ii), the VOHAP 

concentration is missing and 500 ppmw should be inserted. 

Response 8.4: The EPA has corrected the identified errors in the final rule. 

Comment 8.5: Commenter 64 states that the wording in 40 CFR 63.685(g)(2) is 

confusing and should be revised for clarification.

Response 8.5: The EPA agrees with the commenter, and the final rule has been revised to 

clarify the requirements of 40 CFR 63.685(g)(2).

Comment 8.6: Commenter 63 asserts the EPA must prohibit routine flaring, set a cap to 

limit special flaring, ensure its efficiency and monitor flaring. The commenter states that the 

EPA must update the standards to assure that flares follow the practices recommended by EPA’s 

2012 peer-reviewed study – Parameters for Properly Designed and Operated Flares – and which

the EPA is proposing to do for other source categories, since such flares can be used and the 

EPA is aware of at least one such use. The commenter claims that the changes in flaring use and 

knowledge about flaring are developments that must be considered under CAA section 112(d)(6) 

and that flares without proper limits violates National Lime Association. The commenter argues 

that EPA must at least investigate whether there are uncontrolled HAP emissions from OSWRO 

flares and set limits for them. The commenter further states that the EPA has provided no valid 

basis to distinguish between flares at facilities like refineries and chemical plants and the sources 

under review here, and the EPA must take action to apply the new data on flaring in this 

rulemaking. Considering the new information the EPA now has that flares are less efficient than 

previously understood, the EPA should consider prohibiting the use of flaring, ensure less 

reliance on flaring, requiring flare gas recovery systems, requiring improved flare monitoring 

and ensuring the proper operating parameters are set. The commenter also notes that there is 

evidence that reduced flaring saves money by capturing and rerouting hydrocarbons for 

reprocessing and use. 

Response 8.6: Based on information currently available to the EPA, we do not agree with 

the commenter that flaring must be limited as a control option or that the EPA must update the 

OSWRO NESHAP to assure that flares follow the practices recommended by EPA’s 2012 peerreviewed study – Parameters for Properly Designed and Operated Flares (the "Flare Study"). 

Responses to the CAA section 114 questionnaire from OSWRO sources indicate that 

flares are not commonly used as control devices for this source category, and we know of only 

one facility in this source category that uses a single flare as a primary control device in order to 

comply with the OSWRO NESHAP. This single flare is a non-assisted flare, and the combustion 

takes place in a partial enclosure at ground level. This is not typical of the elevated flare designs 

in the Flare Study. As indicated in the Flare Study, one of the primary factors that affects flare 

performance is over-assisting flares with too much steam or air, and while this can potentially 

occur in steam-assisted and air-assisted flare designs, non-assisted flare types do not have a 

potential to over-assist. We have no information to suggest that the non-assisted flares at 

OSWRO sources are achieving poor destruction efficiency. In addition, none of the flare 

performance data used in the study comes from OSWRO sources. While the commenter asserts 
36

that the EPA must apply the “new data” on flaring in this rulemaking, the commenter did not 

identify any specific new data that should be applied or demonstrate that any such data are 

relevant to the OSWRO source category. The EPA also requested information regarding flares in 

the preamble to the proposed rule including: “Frequency of flaring; number and types of flares 

used; waste gas characteristics such as flow rate, composition and heat content; assist gas 

characteristics such as target assist gas to waste gas ratios and minimum assist gas flow rates; 

use of flare gas recovery and other flare minimization practices; and existing flare monitoring 

systems.” We did not receive any comments with additional information responsive to this 

request.

Regarding the issue of banning routine flaring, we note that flare minimization has been 

required in NSPS Ja for Petroleum Refinery flares, but even in this standard, we did not find it 

practicable to ban routine flaring or to set a hard cap. Instead, we required owners and 

operators to assess measures to minimize waste gas flaring, monitor flare gas flows, and conduct 

root cause analyses for events exceeding baseline flows. We recognized that owners and 

operators must have the ability to account for site specific factors regarding the amount of waste 

gas flared, the ability to recover waste gas and offset natural gas purchases, and other 

considerations that precluded setting a hard one-size-fits-all limit for all refinery flares. We 

would similarly not consider setting a hard limit for OSWRO flares, and because of the very 

limited use of flaring in the OSWRO source category, we would not consider requiring similar 

flare gas minimization measures.

We also disagree with the commenter’s allegation that the OSWRO NESHAP fails to 

establish HAP limits for flares and that the EPA must investigate whether there are uncontrolled 

HAP emissions from OSWRO flares and set limits for them. We believe the commenter does not 

understand the emission sources for which we established MACT standards in the NESHAP. The 

HAP emission limits apply to the OSWRO emission points, such as tanks, process vents, etc., and 

the flare is one type of control technology that may be used to meet those limits. As discussed in 

the preamble to the proposed rule, the existing OSWRO MACT rule provides that OSWRO 

sources may choose from a variety of control techniques with a 95-percent HAP destruction 

efficiency or a flare to control emissions from this source category. Flares are expected to 

achieve 98 percent HAP destruction efficiency when designed and operated according to the 

requirements in the General Provisions to 40 CFR part 63. The OSWRO MACT at 40 CFR 

63.693(h)(1) requires compliance with the General Provisions flare requirements in 40 CFR 

63.11(b) which provides that flares used for compliance be: (1) steam-assisted, air-assisted, or 

non-assisted; (2) operated at all times when emissions may be vented to them; (3) designed for 

and operated with no visible emissions (except for periods not to exceed a total of 5 minutes 

during any 2 consecutive hours); and (4) operated with the presence of a pilot flame at all times 

(using a thermocouple or other heat sensing device and record for each 1-hour period as 

required by the OSWRO MACT at 63.683(h) that the pilot flame is continuously present). The 

General Provisions also specify requirements for both the minimum heat content of gas 

combusted in the flare and maximum exit velocity at the flare tip. The OSWRO MACT then 

requires that a compliance demonstration be conducted by the owner/operator to demonstrate 

all flare requirements are met. The single flare at the one facility in the OSWRO source category 

is currently subject to the flare requirements in the General Provisions summarized above. The 

facility reported a 98 percent HAP destruction efficiency for the flare in its CAA section 114 

response, which is included in the docket for this rulemaking. 

We also disagree with the statement that there is no valid basis to distinguish between 
37

flares at facilities like refineries and chemical plants and OSWRO sources. For flares in the 

OSWRO source category, the EPA has made no determination of insufficient regulatory 

requirements or poor operational performance. The EPA has proposed to update flare 

requirements for one source category, petroleum refineries, pursuant to CAA section 112(d)(2) 

and (3), to ensure compliance with the 98 percent HAP reduction requirement in the refinery 

MACT standards. As discussed in the refineries proposal preamble, the potential for reduced 

flare performance is attributable to flare minimization efforts at refineries (79 FR 36905, June 

30, 2014), which have led to an increasing number of flares operating at well below their design 

capacities. This minimization effort has resulted in reduced flaring of gases at refineries, and 

thus, has also resulted in over assisting the flare with steam or air at some refinery flares, 

leading to the degradation of flare combustion efficiency. As discussed in the refineries proposal 

preamble, for the 510 flares in the refinery source category, 90 percent are steam-assisted or 

air-assisted flares. 

We disagree with the commenter that we should amend the operating requirements for 

flares in the OSWRO source category, and we are not at this time promulgating any changes to 

the currently applicable regulations pertaining to the performance of flares for this source 

category. 

Comment 8.7: Commenter 63 states that the EPA should create a community complaint 

mechanism that ensures citizen complaints concerning air pollution receive an immediate 

response, in which the EPA commits to initiate an investigation and provide a publicly available 

report of the investigation results, including whether it leads to an enforcement action, within 7 

days.

Response 8.7: The EPA takes citizen pollution complaints seriously and is committed to 

responding to complaints. We invite the public to help us protect our nation's environment by 

identifying and reporting environmental violations. The EPA's Report an Environmental 

Violation website provides a way for the public to report suspected environmental violations. 

(http://www.epa.gov/compliance/complaints/moreinfor.html)

Assuring compliance with our nation's environmental laws is one of EPA's primary

commitments. In carrying out this responsibility, we use many different approaches. One 

approach is to seek help from the public by asking it to provide EPA with information about 

potentially harmful environmental activities in communities and workplaces. Reports from the 

public have led to state and federal enforcement cases and ultimately served environmental 

protection well.