E.O. 12866 Review 2060-AQ-42 email+att 4 012011 .txt

From: French.Chuck@epamail.epa.gov

Sent: Thursday, January 20, 2011 12:06 PM

To: cortney_higgins@omb.eop.gov

Cc: Guinnup.Dave@epamail.epa.gov; Talcott.Fred@epamail.epa.gov; 

tierney.jan@epamail.epa.gov; Stewart.Michael@epamail.epa.gov; Laney, 

Michael N.; Westlin.Peter@epamail.epa.gov; Fruh.Steve@epamail.epa.gov; 

Benner.Tim@epamail.epa.gov; Hanzel, Veronica; 

Nizich.Sharon@epamail.epa.gov

Subject: Part of E.O. 12866 Review: EPA Staff Response to OMB questions pertaining 

to Primary Lead RTR pertaining to comments Regarding Affirmative Defense - received 

per Bin 1 and Bin 2 RTR 

proposal, RIN 2060-AQ42

Attachments: 3XX_2010-12-06 API Marine Vessel Loading RTR Comments.pdf; EPA-HQOAR-2010-0600-0262.1.pdf; EPA-HQ-OAR-2010-0600-0264.1.pdf; EPA-HQOAR-2010-0600-0265.1.pdf; EPA-HQ-OAR-2010-0600-0273.1.pdf

Hi Cortney,

 Attached are some of the comments that we received in response

to the RTR Bin 1 and Bin 2 Proposal regarding Affirmative Defense. I

will keep looking through the comments, and depending what I find, I may

be sending you more later today. Meanwhile, let us know if you have

questions.

Thanks.

Chuck French, EPA

(See attached file: 3XX_2010-12-06 API Marine Vessel Loading RTR 

Comments.pdf)(See attached file: EPA-HQ-OAR-2010-0600-0262.1.pdf)(See

attached file: EPA-HQ-OAR-2010-0600-0264.1.pdf)(See attached file:

EPA-HQ-OAR-2010-0600-0265.1.pdf)(See attached file:

EPA-HQ-OAR-2010-0600-0273.1.pdf)

Page 1
Matthew Todd

Regulatory and Scientific Affairs

1220 L Street, NW

Washington, DC 

20005-4070 USA

Telephone: 202-682-8319

Fax: 202-682-8031

Email: ToddM@api.org

www.api.org

December 6, 2010 

Air and Radiation Docket

U.S. EPA

1301 Constitution Ave., NW

Room 3340

Washington, DC 20004

a-and-r-docket@epa.gov

Ref.: Docket ID No. EPA-HQ-OAR-2010-0600

Comments on EPA’s Proposed Rule – Residual Risk and Technology Review (RTR)

“National Emission Standards for Marine Tank Vessel Loading Operations”

75 Federal Register 65068 (October 21, 2010)

The American Petroleum Institute (API) appreciates the opportunity to comment on the Environmental 

Protection Agency’s (EPA or Agency) proposed revisions to 40 CFR Part 63 Subpart Y, ―National Emission 

Standards for Marine Tank Vessel Loading Operations‖ (MTVLO) published October 21, 2010 [75 Federal 

Register 65068], which result from EPA’s residual risk and technology review (RTR) of the MTVLO rule.

The American Petroleum Institute (API) is a national trade association with nearly 400 member companies 

that are involved with all aspects of the oil and natural gas industry. 

While we are, with certain exceptions, supportive of the outcome of EPA’s RTR review of the MTVLO rule, 

we object to proposed changes in the rulemaking process with respect to the evaluation of risk to public 

health. Our concerns are discussed below.

RESIDUAL RISK DETERMINATION

API has two general concerns with respect to the manner in which EPA evaluated residual risk. The first 

concern is that there were errors in EPA’s evaluation which resulted in certain facilities appearing to pose

greater risks to public health than would have been predicted by a more accurate analysis. The second 

concern is that EPA is proposing to change the protocol for determining residual risk in a manner that lacks 

statutory authority and which is inappropriate and unnecessary. These concerns are discussed below.

1. ERRORS IN THE DETERMINATION OF RESIDUAL RISK. While EPA correctly concluded that 

the health risk from the MTVLO source category is acceptable and that the existing rule provides an 

ample margin of safety,1the health risk determined by EPA was overstated due to errors in EPA’s 

 

1

75 Federal Register 65068-65149, October 21, 2010; page 65114, last two columns.
2

evaluation. These errors included errors or out-of-date data in the 2005 National Emission Inventory 

(NEI), errors in the latitude/longitude location of sources in EPA’s modeling (including mislocation of 

sources into offsite residential areas), and an error by one facility in the identification of a compound 

(i.e., naphtha emissions were incorrectly identified as naphthalene). As discussed in the report included 

as Attachment 1 to these comments, the actual health risk for the facilities identified by EPA as posing 

the highest risk is much lower than reported by EPA.

2. CHANGE IN THE PROTOCOL FOR DETERMINING RESIDUAL RISK. As noted in the 

Federal Register (FR) announcement, EPA is required under section 112(f) of the Clean Air Act (CAA) 

to evaluate the risk to public health that remains after implementation of the technology-based national 

emission standards for hazardous air pollutants (MACT standards). EPA proposes, in this rulemaking, to 

change the manner in which this ―residual risk‖ is evaluated. API has several concerns with respect to 

these proposed changes. 

2.1. Lack of statutory authority for the changes. As EPA notes, the process that the agency has 

followed for residual risk evaluations was established in accordance with a protocol mandated by 

the CAA, including preparation and submission to Congress of the methods to be employed. 

These methods include the two-step process described in the FR announcement. The first step in 

this process is to determine whether the maximum individual lifetime cancer risk (MIR) exceeds a 

presumptive limit of approximately 1-in-10 thousand. When the MIR is determined to be below 

this limit, the residual risk is deemed to be acceptable and the analysis moves to the second step. 

The second step, for situations in which the MIR is above 1-in-1 million, is to determine whether 

the standard provides an ―ample margin of safety‖ to protect human health. EPA has established 

certain metrics for the determination of ample margin of safety through both the agency’s report to 

Congress and an extensive history of subsequent rulemaking.

API believes that EPA lacks statutory authority to make significant and substantive changes

unilaterally to this procedure that has been established in accordance with CAA mandates, vetted 

with Congress, and ratified by precedent. There has been no indication from Congress or 

experience which indicates that the established procedure for evaluating residual risk has failed to 

be protective of human health. API objects to arbitrary changes which are unnecessary and 

unauthorized, and which needlessly add further uncertainty and complexity to a process that is 

already unduly burdensome.

2.2. Inappropriateness of the changes. The new measures which EPA proposes to apply to the 

determination of acceptable risk and ample margin of safety are inappropriate. These new 

measures include:

 - ―total facility‖ consideration; consideration of risk from the total facility, rather than from only 

the portion of the facility subject to the rule,

 - ―demographic‖ consideration; consideration of risk across selected social, demographic, and 

economic groups within the population living near the facility, and

 - ―allowable emissions‖ consideration; consideration of the hypothetical risk associated with the 

level of emissions allowed by the MACT standard (versus the actual emissions from the facility).
3

Each of these considerations is discussed below and in Attachment 1.

2.2.1. Total facility regulation is not legal. If an unacceptable health risk is posed to the 

community by a facility due to emission sources that are not part of the affected source of 

the rule in question, then those emission sources should be addressed in separate rulemaking. 

The MACT standards have defined boundaries of applicability so as to bring some measure 

of order to a highly confusing and complex regulatory framework. Consideration of 

emission sources outside of those boundaries would unravel what semblance of order 

presently exists. Furthermore, in the event that further reductions could be reasonably 

achieved for the emission sources that are subject to the MACT standard in question, such 

measures would be determined in the technology review process.

Finally, EPA does not have authority to consider the combined emissions from entire 

facilities when making § 112(f) risk assessment for a given source category, in that the CAA 

requires residual risk determinations to be conducted on a category by category basis. 

Paragraph § 112(f)(2)(A) provides that, ―If standards promulgated pursuant to subsection (d) 

of this section and applicable to a category or subcategory of sources emitting a pollutant (or 

pollutants) classified as a known, probable or possible human carcinogen do not reduce 

lifetime excess cancer risks to the individual most exposed to emissions from a source in the 

category or subcategory to less than one in one million, the Administrator shall promulgate 

standards under this subsection for such source category‖ (emphasis added). This provision 

unambiguously requires the § 112(f) risk assessment to be focused exclusively on 

―emissions from a source in the category or subcategory.‖ For this reason, EPA does not 

have authority to conduct a residual risk review for more than a single source category or 

subcategory at a time.

2.2.2. Demographic considerations should not arbitrarily trump sound risk assessments. The 

established methodology for evaluating residual risk is based on ―risks to the individual most 

exposed,‖ without regard to the ethnicity, income level, education level, or other socioeconomic factors concerning that individual. Under Section 112(f)(2) of the Clean Air Act, 

residual risk standards must be set:

“If [MACT] standards...applicable to a category or subcategory of sources...do not reduce 

lifetime excess cancer risk to the individual most exposed to emissions from a source in the 

category or subcategory to less in one in a million, the Administrator shall promulgate 

standards...”

The decision whether or not to set residual risk standards, then, is based on risk to the 

―individual most exposed,‖ not the demographic distribution of risk.

EPA’s proposal to introduce demographic analyses to the determination of acceptable risk 

suggests a protocol in which risk to some individuals is deemed more acceptable than risk to 

other individuals. EPA refers to the use of demographic analyses to inform the 
4

determination of risk acceptability as ―an evolving science.‖ In fact, it is not a science at all, 

but rather it is a political judgment, and it has no place in a scientific evaluation of risk to

public health.

The CAA mandate under § 112(f)(2)(A) is expressly to ―provide an ample margin of safety 

to protect public health.‖ It is not reasonable to construe the term ―public health‖ as used in 

§ 112(f) as allowing consideration of demographic classifications that bear no relationship to 

the potential health effects presented by the hazardous air pollutants (HAPs) at issue for the 

given source category or subcategory. 

EPA’s proposal would unreasonably inject racial, ethnic, and other policy considerations 

into a program designed to provide protection for the public at large. For example, EPA 

suggests that the population without a high school diploma should receive extra scrutiny, yet 

does not afford the same scrutiny to other reasonably definable educational groups, such as 

those with a high school diploma, those with college degrees, and those with advanced 

degrees. EPA is apparently making judgments or assumptions about the population without 

a high school diploma, distinct from the population living in poverty and the populations of 

the selected ethnic groups, but EPA fails to explain what those assumptions are or to provide 

any data to support the selection of this population for extra scrutiny.

There is simply no principled way to identify and define those groups that should receive 

extra scrutiny from those that do not. In short, EPA’s approach would inappropriately cause 

arbitrary policy and political considerations to trump objective scientific analysis. This is 

patently unreasonable and, as such, is not a supportable interpretation of § 112(f).

2.2.3. EPA’s allowable emissions approach is arbitrary and excessive. The established 

methodology for evaluating residual risk is based on estimates of actual emissions, but EPA 

proposes to further consider so-called ―MACT allowable‖ emissions. EPA created these 

MACT allowable emissions by assigning an arbitrary ratio to the estimated actual emissions, 

without consideration of process limitations or enforceable permit limits. In that these 

MACT allowable emissions are at best hypothetical and the entire risk assessment protocol 

is already based on worst-case assumptions, rather than average or central-tendency values, 

there is no need to further bias the risk assessment in an arbitrarily conservative manner. 

EPA already acknowledges that the established method of evaluating health risk is based on 

modeling in a manner that overestimates the concentrate of hazardous pollutants in the 

ambient air, so it seems rather capricious to suggest introducing a hypothetical scenario that 

would further exaggerate the modeled concentration of pollutants. 

PROPOSED CHANGES TO THE MTVLO RULE

3. SUBCATEGORIES THAT ARE PRESENTLY EXEMPT. Two subcategories are exempt from 

control under the existing rule: (i) existing facilities below the 10/25 tpy threshold, and (ii) offshore 
5

facilities. EPA is proposing submerged fill as a new MACT floor for these two subcategories, and 

collection and processing of vapors as a beyond-the-floor measure for those facilities that load at least 1 

million bbl/yr of gasoline.

3.1. Submerged fill is cost effective. EPA states in the preamble that the agency is proposing to 

require submerged fill for both of the previously exempt subcategories. In the actual rule 

language, however, submerged fill is proposed only for offshore facilities [§63.560(d)(6)]. In 

response to a query [docket: EPA-HQ-OAR-2010-0600-0253], EPA indicates that the submerged 

fill requirement would be applied to existing facilities below the 10/25 tpy threshold by a new 

paragraph §63.560(f). API supports the requirement of submerged fill for marine vessel loading 

operations that are not subject to a requirement to collect and process displaced vapors.

3.2. Lowering the applicability trigger from 10 to 1 million bbl/yr of gasoline is illegal. The 

existing rule contains a requirement to collect and process vapors at marine vessel loading 

operations that load at least 10 million bbl/yr of gasoline. EPA proposes to lower this threshold to 

1 million bbl/yr of gasoline loaded (1 M bbl/yr threshold). This lower threshold would potentially 

require collection and processing of vapors at certain facilities that were previously exempt. API 

believes that EPA’s rationale for this change is both confusing and flawed, and that a more correct 

estimate of the cost is in excess of $180,000 per ton of HAP reductions. We believe the proposed 

action to be illegal, and we request that it be rescinded. 

Specific issues are discussed in more detail below.

3.2.1. EPA confuses MACT with RACT. The discussion in the preamble is confusing, at best, 

concerning whether the proposed 1 M bbl/yr threshold is a MACT measure or a RACT 

measure.

The preamble states that the existing MACT standards require collection and control of 

vapors for MTVLO facilities that load at least 10 million (M) bbl/yr of gasoline. However, 

this provision is in the RACT provisions of the existing rule [§63.560(b) and §63.562(c)] 

rather than in the MACT provisions. Furthermore, the preamble justifies the proposed new 1 

M bbl/yr threshold on a VOC (RACT) basis rather than a HAP (MACT) basis. Yet the 

preamble describes this lower threshold as a beyond-the-floor MACT measure for the two 

previously exempt subcategories. 

The preamble also describes this proposed change in terms of lowering the threshold for 

vapor collection and control requirements from 10 M bbl/yr of gasoline loaded to 1 M

bbl/yr. The proposal, however, leaves the 10 M bbl/yr threshold unchanged in the RACT 

provisions of §63.560(b) and §63.562(c), but adds a new 1 M bbl/yr threshold in the MACT 

provisions of §63.562(b).

The discussion of the 1 M bbl/yr threshold in the preamble should be consistent with both 

the basis presented for justification of this measure and the language of the rule.
6

3.2.2. Illegal as a MACT measure. As noted above, the 1 M bbl/yr threshold is presented as a 

MACT measure in the preamble discussion and in the manner in which this requirement is 

proposed to be implemented in the rule language. The preamble describes the proposed 1 M 

bbl/yr threshold as a ―beyond-the-floor‖ MACT standard.2 This determination, however, 

would require the measure to be reasonably cost effective in reducing HAPs, in that the 

statutory authority given under CAA Section 112(d) is expressly for the reduction of HAPs. 

EPA estimated a cost for HAP reduction of $74,000 per ton, which EPA characterizes as 

―higher than our historical values,‖3 Furthermore, EPA’s cost effectiveness calculation is 

seriously flawed, as discussed below. One of the errors in EPA’s calculation was to assume 

a HAP level more than twice that which would be reasonably expected in gasoline vapors 

(see Attachment 2). Correcting to a conservative value of 3% HAP, rather than the 7.3% 

value assumed by EPA, would change EPA’s calculated cost effectiveness from $74,000 per 

ton to $180,000 per ton of HAP reductions. EPA acknowledges even the $74,000 per ton to 

be ―higher than our historical values,‖ and thus the corrected value of $180,000 per ton is 

clearly not reasonable. Given that it is not a cost-effective measure for the control of HAP, it 

is illegal to promulgate this requirement as a MACT measure.

3.2.3. Cost effectiveness calculation flawed. EPA’s evaluation of cost effectiveness 4relies on 

undocumented assertions and assumptions. The assumed cost of equipment was based on an 

unsubstantiated verbal claim from a single equipment vendor, and the installation cost was 

estimated using ―EPA standard costing procedures.‖ This methodology relies on an assumed 

ratio of installation costs to equipment cost, but EPA failed to document that this ratio is 

reasonable for the particular case of installing vapor control systems at MTVLO facilities. 

Furthermore, the type of control equipment offered by the vendor in question is lean oil 

absorption, which is not in common usage for controlling vapors from sources in the 

petroleum industry. EPA’s cost effectiveness evaluation relied on an assumption that this 

technology is 99% effective in recovering VOCs, but EPA failed to present any evidence to 

substantiate this assumption, and API members doubt lean oil systems are 99% effective in 

practice. In fact, EPA failed to establish that this technology has ever been demonstrated in 

practice to be effective for MTVLO applications. In addition, EPA assumed the HAP 

content of gasoline vapors to be 7.3%, which is more than twice the value of 3% that is 

shown in Attachment 2 to be conservative. As noted previously, this one correction would 

increase the estimated cost of HAP reductions from $74,000 to $180,000 per ton. Given the 

numerous unsupported assumptions, EPA’s determination of cost effectiveness is seriously 

flawed.

 

2

75 Federal Register 65068-65149, October 21, 2010; page 65116, first column.

3

75 Federal Register 65068-65149, October 21, 2010; page 65115, last column.

4 Memorandum from David Green and Karen Schaffner, RTI International to Stephen Shedd and Brenda 

Shine, EPA, “Cost Effectiveness and Impacts of Lean Oil Absorption for Control of Hazardous Air Pollutants 

from Gasoline Loading – Residual Risk and Technology Review for the Marine Tank Vessel Loading 

Operations Source Category,” August 19, 2010 [Docket Document ID: EPA-HQ-OAR-2010-0600-0003].
7

3.2.4. Affected MTVLO may not be major sources of HAP. The preamble concludes that the 

HAP major source criteria would be triggered by the loading of 5 M bbl/yr of gasoline at an 

MTVLO facility. If this is the case, then it would be inappropriate to impose a 1 M bbl/yr 

threshold as a MACT measure, in that MACT measures should be applicable only to major 

sources of HAP. Furthermore, EPA’s determination that the HAP major source criteria 

would be met by the loading of 5 M bbl/yr of gasoline is flawed. The discussion in 

Attachment 2 demonstrates that it would likely require the loading of at least 10 M bbl/yr of 

gasoline to trigger the HAP major source criteria, corresponding to the threshold in the 

existing rule. The arbitrary changes in EPA’s assumptions in support of the proposed rule 

are erroneous and unjustified. It is inappropriate, then, to apply a MACT measure to marine 

facilities that load less than 10 M bbl/yr of gasoline.

3.2.5. Confusing implementation. The proposed lowering of the gasoline loading threshold to 1 

M bbl/yr is not only inappropriate, it is also confusing in the manner that it is implemented 

in the proposed rule language. While proposed edits to §63.562(b)(1) would apply the vapor 

collection and vapor-tightness requirements to facilities that load at least 1 M bbl/yr of 

gasoline, the control standard (emissions limit) for these facilities is specified separately in a 

proposed new paragraph §63.562(f). The manner in which this is done results in the 

following provisions not being applicable to the new subcategory:

- §63.562(b)(5) Prevention of carbon adsorber emissions during regeneration.

- §63.562(b)(6) Maintenance allowed for loading berths. 

- §63.563(b) Compliance determination for affected sources (initial performance test).

In that this situation is not discussed in the preamble, it is not apparent whether EPA 

intended for these provisions to not apply to the new subcategory of facilities that load at 

least 1 M bbl/yr of gasoline.

3.2.6. Application to offshore facilities not justified. The proposed revisions would apply the 

requirement to collect and process vapors from MTVLO to facilities that load at least 1 

million bbl/yr of gasoline, regardless of whether the facility is located onshore or offshore. 

EPA failed, however, to demonstrate any benefit that would accrue from applying this 

requirement to offshore facilities, and EPA’s cost evaluation did not address the particular 

cost impacts associated with an offshore location. 

EPA did not assess the nature and fate of emissions from marine vessel loading operations 

located offshore in order to determine whether such emissions would be reasonably 

anticipated to endanger public health or to contribute materially to ozone non-attainment 

status. In that offshore facilities, by the definition given in §63.561, have loading operations

located at least 0.5 miles from the shore, and there are no permanent residents located 

immediately on the shoreline, there is an inherent buffer between these facilities and the 

potentially affected population that is not necessarily present for an onshore facility. The 

impact of emissions from offshore facilities, then, would be expected to be substantially less 

than from a similar onshore facility. 

Offshore facilities are typically quite different from most onshore MTVLO facilities, in that
8

most onshore facilities large enough to be subject to the proposed rule are not dependent

solely on marine loading for distribution of product. They are either located on a pipeline 

network and/or distribute product via a truck rack and distribute most of their product in this 

fashion, and thus have limited needs for docks and loading operations. Part of the reason for 

this is that the Jones Act requires US flag vessels for transfers between US ports and there 

are very few US ships capable of carrying large cargoes of petroleum products, so that 

marine shipment is disfavored for most US MTVLO facilities that have other distribution 

options. Offshore facilities are typically very large facilities that distribute most or all of 

their product/crude oil via ships, rather than barges. The result is that offshore facilities have 

many loading berths located on very long piers farther from shore, so that ships large enough 

to economically distribute the products can berth at them.

As a result, the offshore location requires much greater capital expenditure in order to install 

controls. This additional cost would include either additional offshore platform structure to 

support the vapor control equipment, or piping from the offshore facility to carry vapors to

onshore vapor control equipment. The preamble to the existing rule cited these costs as 

being ―between two and five times more expensive than comparable onshore control 

techniques.‖5 Comments from at least one company which qualifies as an offshore facility 

support the much higher cost of controls at these locations. In the new rulemaking, however, 

EPA’s cost-effectiveness evaluation uses a fixed assumption for the costs to install controls, 

without regard for the particular cost issues associated with an offshore location.6 It also 

relies on technology not in use at MTVLOs or offshore facilities. In that EPA failed to 

evaluate cost effectiveness in a manner that accounted for the particular considerations 

associated with the offshore subcategory, EPA cannot claim to have made a determination of 

reasonable cost effectiveness for this subcategory.

In the 1995 final rule for MTVLO, EPA recognized these issues pertaining to offshore 

facilities. EPA concluded that, in light of the ―significantly higher costs and poor cost 

effectiveness shown by these sources . . requirement for controls at offshore RACT terminals 

would not be consistent with the requirements for the technology to be ―reasonable.‖‖7 EPA 

has not presented any documentation in the new rulemaking that would support a change to 

this conclusion. Proposed new paragraph §63.560(d)(6)(ii) should therefore be deleted.

4. STARTUP, SHUTDOWN, AND MALFUNCTION PROVISIONS. Given that the existing rule does 

not require a startup, shutdown, and malfunction (SSM) plan, and the SSM exemption has been vacated 

by the courts, API supports EPA’s edits to render SSM references in the General Provisions not 

applicable. API also supports EPA’s proposal to address malfunctions as distinct from routine operating 

 

5

60 Federal Register 48388-48417, September 19, 1995; page 48393, middle column.

6 Memorandum from David Green and Karen Schaffner, RTI International to Stephen Shedd and Brenda 

Shine, EPA, “Cost Effectiveness and Impacts of Lean Oil Absorption for Control of Hazardous Air Pollutants 

from Gasoline Loading – Residual Risk and Technology Review for the Marine Tank Vessel Loading 

Operations Source Category,” August 19, 2010 [Docket Document ID: EPA-HQ-OAR-2010-0600-0003].

7

60 Federal Register 48388-48417, September 19, 1995; page 48393, middle column.
9

conditions, but we object to the manner in which EPA proposes to do so. API believes it is illegal to 

subject malfunction events to an emissions standard for which EPA did not consider the emissions or 

costs of control associated with malfunctions. API endorses the comments submitted separately from the 

SSM Coalition on this issue, particularly with respect to establishing an alternative emissions limitation 

for malfunctions. Specific recommendations for an alternative emissions limitation for MTVLO 

malfunctions are presented below.

4.1. Notifications and reports for malfunctions. Proposed paragraph §63.562(e)(7)(ii) would require 

a notification of a malfunction to be submitted within 2 business days after the initial occurrence of 

the malfunction in order to preserve an affirmative defense. This paragraph would additionally

require a report within 30 days after the malfunction. These deadlines are arbitrary, unrealistic, 

and unwarranted.

4.1.1. The proposed 2-day notification is unrealistic and unnecessary. The provisions of 

§63.562(e)(7)(i)(A)–(I) would specify a 9-step procedure for determining whether a given 

malfunction event qualifies for the affirmative defense. In most cases, it would not be 

realistic to complete this determination process within 2 days following the occurrence of the 

event. Facilities might therefore tend to routinely submit the 2-day notification in order to 

preserve the potential for an affirmative defense, even in cases which subsequently are 

determined to not qualify. Furthermore, there is no environmental benefit that would accrue 

from this notification, and similar provisions in refinery consent decrees do not require it. 

The result of this unrealistic and unnecessary requirement, then, would be to burden both the 

facility and the regulatory agency having jurisdiction with the processing of paperwork that 

has no associated environmental benefit.

4.1.2. Malfunction reports should be submitted with the semi-annual reports. The rule 

already requires, at §63.567(e), the submission of excess emissions and continuous 

monitoring system performance and summary reports on a semi-annual basis, and EPA has

established the semi-annual basis as being appropriate for all compliance-related reporting 

through numerous rulemakings under Part 63. In fact, EPA promulgated the Recordkeeping 

and Reporting Burden Reduction Rule for the expressed purpose of simplifying and unifying 

reporting schedules. EPA stated this intent in the preamble to that rule:

“The Agency now believes that the semiannual reporting frequencies contained in recently 

promulgated NSPS and NESHAP regulations and proposed in this rulemaking for all types of 

information are generally appropriate. . . EPA sees no reason to retain different reporting 

frequencies in the NSPS and NESHAP General Provisions compared to the reporting 

frequencies contained in recently promulgated rules.” 8

As noted by EPA, there is no reason to require a reporting frequency that differs from the 

semi-annual basis adopted by the agency. It would be contrary to the agency’s own 

assessment of an appropriate reporting frequency to arbitrarily require malfunction reports to 

be submitted within 30 days.

 

8

61 Federal Register 47840-47852, September 11, 1996; page 47844, first two columns.
10

4.2. §63.562(e)(7)(i)(A)–(I) should constitute a work practice for compliance. The steps specified 

in §63.562(e)(7)(i)(A)–(I) should be specified as a work practice for compliance in the event of a 

malfunction, rather than being specified as a basis for an affirmative defense. In the preamble to 

the proposed rule revisions, EPA presents numerous reasons for not accounting for malfunctions in 

the setting of emission standards for routine operating conditions, yet proposes to apply these 

emission standards to malfunction events.

9

 This is logically inconsistent and statutorily 

inappropriate. If the standards are to apply to malfunction events, then the emissions and costs of 

control associated with malfunction events should have been included in the evaluation of the 

standards. As explained by EPA, however, not only was this not done – it would not be feasible to 

do so.

On the one hand, then, EPA is obligated to set standards that are ―achievable‖ under Section 

112(d)(2) of the Clean Air Act. On the other hand, it is not feasible to develop an emission 

standard that governs malfunction periods. This scenario is expressly addressed in Section 112(h)

of the Clean Air Act, which allows EPA to set work practice standards for situations where ―it is 

not feasible in the judgment of the Administrator to prescribe or enforce an emission standard . . .‖ 

Malfunctions fit within the situations described in the definition of ―not feasible to prescribe or 

enforce an emission standard‖ as any situation where ―the application of measurement 

methodology to a particular class of sources is not practicable due to technological and economic 

limitations.‖ Consequently, EPA should set work practice requirements to address periods of 

malfunction. The steps set forth in §63.562(e)(7)(i)(A)–(I) would constitute an appropriate work 

practice standard for malfunctions.

4.3. Provide an allowance for reasonable periods of maintenance. EPA should provide an 

allowance for a reasonable period of routine maintenance for the control device. Proper operation

of a control device includes periodic routine maintenance, and manufacturers of control devices 

typically recommend preventive maintenance on a semi-annual basis. EPA has stipulated in other 

rulemakings10 that standards do not apply during planned routine maintenance, other than a work 

practice standard that such periods shall not exceed 240 hours per year and records must be 

maintained to document such periods.

5. CITATION ERRORS IN THE PROPOSED RULE LANGUAGE. API has identified two 

paragraphs cited by the proposed revisions which do not exist.

5.1. Proposed edits to §63.560(a)(1), (2) & (3) refer to a paragraph (f) ―of this section,‖ but there is no 

paragraph (f) of section §63.560. This would be reconciled by adding a new paragraph §63.560(f), 

as described in EPA’s response to a query [docket: EPA-HQ-OAR-2010-0600-0253].

5.2. Proposed edits to Table 1, at §63.10(c)(10) & (11), include a reference to §63.657(m)(1) for 

reporting malfunctions, but there is no paragraph §63.657(m).

 

9

75 Federal Register 65068-65149, October 21, 2010; page 65074, last two columns, and page 65075, first 

column.

10 Examples of regulatory provisions for maintenance of the control device include 60.102a(f)(3) and 

63.119(e)(3) & (4).
11

6. MISCELLANEOUS EDITORIAL COMMENTS.

6.1. Proposed edits to §63.562(b)(1)(i) should read ―1 million bbl/yr of gasoline‖ rather than ―1 M 

barrels of gasoline,‖ so as to read correctly and to be consistent with proposed edits to 

§63.562(b)(1)(ii) and (iii).

We appreciate your consideration of our comments. If you have any questions, please contact me at 202-

682-8319 or toddm@api.org.

Sincerely, 

/s/

Matthew Todd

CC: Mr. Stephen Shedd, EPA (shedd.steve@epa.gov) 
ENVIRON International Corporation • Marketplace Tower • 6001 Shellmound Street, Suite 700 • Emeryville, California 94608

Voice: 510-655-7400 • Fax: 510-655-9517

ATTACHMENT 1 – Report from Environ on EPA’s Residual Risk Determinations

November 30, 2010

MEMORANDUM

To: Matt Todd, American Petroleum Institute

From: Stan Hayes, ENVIRON 

Subject: Comments on EPA’s Residual Risk Determination of Marine Vessel Loading 

Operations Facilities

On October 21, 2010, EPA published in the Federal Register (75 FR 65068) a proposed 

rule that addresses Clean Air Act residual risk and 8-year technology review requirements for six 

National Emission Standards for Hazardous Air Pollutants (NESHAP) and sixteen source 

categories subject to those standards, including facilities conducting marine vessel loading 

operations (MVLO) and subject to the Marine Tank Vessel Loading Operations NESHAP (40 

CFR 63 Subpart Y). Comments on the proposed rule and supporting material are due to EPA on 

or before December 6, 2010. 

In its proposal and supporting material, EPA estimated the residual risk associated with 

facilities subject to each of the six NESHAP, including MTVLO facilities. To assist in its 

preparation of comments, the American Petroleum Institute (API) retained ENVIRON to review 

and evaluate EPA’s determination of residual risk for MTVLO facilities, focusing particularly on 

those facilities for which EPA calculated a cancer maximum individual risk (MIR) from 

MTVLO sources greater than 1 in a million. As a part of that review and evaluation, ENVIRON 

also examined the general methodology by which EPA’s RTR residual risk assessments were 

done.

A. ERRORS IN EPA’S DETERMINATION OF MTVLO RESIDUAL RISK 

With its proposed rule (EPA 2010a), EPA also published residual risk estimates for each 

of 152 modeled MTVLO facilities, both from MTVLO sources only and facility-wide (EPA 

2010b). As summarized in Table 1, EPA calculated that cancer maximum individual risks (MIR) 

from MTVLO sources were greater than 1 in a million for just three of the 152 facilities 

modeled. 

None of the 152 modeled facilities were estimated to have noncancer target organ 

specific hazard indexes (TOSHI) from MTVLO sources that exceeded 0.3 for actual emissions, 

well below the generally used maximum acceptable level of 1. EPA also calculated that the total 
ENVIRON memo

13

cancer incidence from actual emissions from MTVLO sources at the 152 modeled facilities was 

0.01 excess cancer cases per year, or one case in every 100 years.

Table 1. Facilities for which EPA estimated MTVLO cancer MIR 

greater than 1 in a million

EPA Estimated Risk from 

MTVLO Sources Based On

Actual Emissions

Facilities

Cancer MIR 

(in million)

Noncancer 

Chronic 

TOSHI

EPA CANCER MIR > 1 IN MILLION IN PROPOSED RULE

Texas Petrochemicals (Houston) 20 0.3

KM Galena Park Terminal (Galena Park) 20 0.2

Chevron / Unocal (Nederland) 10 0.1

ALSO IDENTIFIED IN PRELIMINARY DISCUSSIONS WITH API

TM Coastal (Ft. Lauderdale) 0.3 0.001

Total EPA modeled facilities = 152

Based on its MTVLO residual risk analyses, EPA concluded that risks from the MTVLO 

source category are acceptable:

“Based on this low cancer risk level and in consideration of other health 

measures and factors, including the low cancer incidence (one case in every 100 

years) and the low maximum noncancer risk level (TOSHI of 0.3 based on actual 

emissions and 0.5 based on MACT –allowable emissions), we propose that the 

risks from the MTVLO source category are acceptable.”

As a result, EPA proposed to re-adopt existing MACT standards:

“Therefore, we continue to propose that the current MACT-based standards 

provide an ample margin of safety to protect public health and the environment, 

and we are proposing to re-adopt the existing MACT standards to satisfy section 

112(f) of the CAA.”

Our review of EPA’s MTVLO residual risk analyses provides additional support to 

EPA’s conclusion that risks from the MTVLO source category are acceptable. We have 

identified a number of data errors that have caused EPA to overestimate risk from each of those 

facilities for which EPA calculated an MTVLO cancer MIR greater than 1 in a million. Risks for 

these facilities, when re-calculated using corrected data, demonstrate that both MTVLO source 

and facility-wide risks are lower than calculated by EPA. Data errors that were identified 

include:
ENVIRON memo

14

(a) Incorrect specification of latitude/longitude coordinates of numerous sources in the 

2005 NEI used by EPA as its baseline reference, with some sources mislocated off 

site in residential areas

(b) Incorrect calculation of emissions due to such factors as:

 Misclassification of naphtha (a major class of VOCs) as naphthalene (a specific 

HAP)

 Incorrect speciation of tank HAP emissions.

In addition, more-current 2009 emission data or other related information provided for 

several of the facilities analyzed indicate that significant emission reductions have occurred since 

the 2005 baseline year for EPA’s MTVLO residual risk assessments. These reductions have 

resulted from voluntary emission reduction measures, compliance with post-2005 regulatory 

requirements, and agreements with regulatory agencies and local governments.

In discussions with API earlier this year, EPA indicated that their preliminary residual 

risk assessments had identified four facilities for which the estimated cancer MIR for MTVLO 

sources was greater than 1 in a million. EPA identified those facilities as: (a) TransMontaigne 

(TM) in Fort Lauderdale, Florida (previously named Coastal Terminals in EPA’s risk analysis); 

(b) TX Petrochemicals (now TPC Group) in Houston, Texas; (c) KinderMorgan (KM) in Galena 

Park, Texas (previously named the Galena Park Terminal); and (d) Chevron in Nederland, Texas 

(previously named Unocal). Because their preliminary estimates of cancer MIR were greater 

than 1 in a million, EPA stated that particular effort would be focused on those four facilities, 

with EPA staff visiting each of them to observe facility operations and to confirm facility 

information.

Following these pre-proposal discussion with API, ENVIRON was retained by API to 

review and evaluate for their accuracy EPA’s preliminary residual risk estimates for these four 

facilities and the emission and source data on which they were based. Because EPA did not 

provide their preliminary risk assessment data and supporting risk modeling files, ENVIRON 

conducted independent analyses to reconstruct EPA’s residual risk results. Source and emission 

data for the four facilities were extracted from the 2005 NEI used by EPA as its primary baseline 

reference. The HEM-3/AERMOD risk model, which is the same model used by EPA for RTR 

residual risk assessments, was employed to calculate MTVLO category-specific and facilitywide inhalation cancer MIR and chronic noncancer target organ specific hazard indexes 

(TOSHI).

Results of ENVIRON’s risk analyses were used to reconstruct EPA’s preliminary 

residual risk estimates for the four facilities. In conducting these risk analyses, however, data 

errors were identified for all four facilities. These include source location errors, particularly 

involving mislocation of sources into offsite residential areas, that caused EPA’s residual risk 

estimates to be overstated. In addition, data errors involving the use of incorrect or outdated 

emission amounts or incorrect VOC speciation profiles were identified that also caused EPA to 

overestimate residual risk. 
ENVIRON memo

15

Results of our review and analysis of EPA’s residual risk estimates for the four MTVLO 

facilities are as follows:

TransMontaigne – Ft. Lauderdale, Florida. Emission sources listed in the 2005 NEI for 

the TM facility are shown in Figure 1. Of these sources, one has latitude/longitude coordinates 

that correspond to a location on site, just north of a group of tanks near the mid-part of the 

facility. The other sources have the same latitude/longitude coordinates, all corresponding to an 

incorrect, offsite location in a residential area to the west of the facility.

TM staff provided corrected location information for these sources, as shown in Figure 1, 

including the correct locations of the marine vapor recovery unit in the facility’s dock area and 

the Gasoline MACT tank/vapor recovery unit in the central portion of the facility. The HEM-3 

/AERMOD model was used to re-calculate residual risk with corrected location data. Recalculated risk was significantly lower than calculated using the incorrect 2005 NEI location 

data. With corrected data, the cancer MIR was re-calculated to be 0.27 in a million for MTVLO 

sources and 0.30 in a million for all sources facility-wide. Both of these cancer MIR values are 

well below the widely accepted cancer risk de minimis level of 1 in a million. 

In MTVLO residual risk analyses released with its proposed RTR rule, EPA calculated 

that the cancer MIR for MTVLO sources at the TM facility is 0.32 in a million, very nearly the 

value calculated by ENVIRON. This close agreement suggests that, prior to final risk analyses 

for its proposed rule, EPA corrected the marine vapor recovery unit location error present in its 

preliminary, pre-proposal residual risk assessment.

However, in proposed rule residual risk analyses, EPA calculated that TM’s facility-wide 

cancer MIR is 6 in a million. This is about twenty times higher than the value of 0.30 in a 

million calculated by ENVIRON. Reasons for this disparity are not known, but it may be that 

EPA did not correct location errors of non-MTVLO sources. If this is the case, we recommend 

that EPA make those location corrections and re-calculate facility-wide risk. Going forward, the 

corrected data should be incorporated into the 2005 NEI and subsequent versions of that 

database.

Chevron/Unocal – Nederland, Texas. As discussed previously with EPA staff (e.g., 

Chevron 2010, API 2010a, EPA 2010d), naphthalene emissions for the Chevron/Unocal facility 

are incorrectly high in the 2005 NEI due to a mistaken reporting of naphtha as ―naphthalene.‖ 

Naphtha is a product of crude oil distillation that contains a mixture of different hydrocarbons 

that boil within a particular temperature range. Naphtha is thus a broad term referring to this 

mixture of different liquid hydrocarbons, and it is not the same as naphthalene, a specific 

polycyclic aromatic hydrocarbon HAP formed through fusion of two benzene rings.

In its MTVLO residual risk assessment of this facility, EPA correctly identified as an 

MVTLO source the tank for which naphtha emissions are misclassified as naphthalene. 

However, as shown in Figure 2, the latitude/longitude coordinates of this tank in the 2005 NEI 

specify an incorrect location in the midst of a large tank farm, well away from the tank’s actual 

location near marine vessel docks.
ENVIRON memo

16

Because of these errors, EPA calculated the cancer MIR to be 10 in a million, both for 

MTVLO sources and facility-wide. ENVIRON risk modeling conducted using the same 

incorrect 2005 NEI data calculated a cancer MIR of 11 in a million for MTVLO sources and 

facility-wide, closely consistent with EPA’s risk estimate.

With the HEM-3/AERMOD model, ENVIRON re-calculated risk using corrected source 

locations and re-calculated naphthalene emissions, which were determined by facility staff (e.g., 

Chevron 2010) using a corrected VOC speciation profile. The re-calculated cancer MIR was 

0.11 in a million for MTVLO sources and 0.47 in a million facility-wide. Both of these values 

are lower than the cancer risk de minimis level of 1 in a million.
Copyrighted page/s removed. Copyrighted 

material is not available in Regulations.gov since 

it may not be reproduced without consent of the 

copyright holder. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 202-566-1744 

Fax: 202-566-9744 

Email: docket-customerservice@epa.gov
ENVIRON memo

19

Because EPA continues to list the cancer MIR for the facility as 10 in a million in its final 

residual risk analyses for the proposed RTR rule, it may be that EPA has not yet corrected the 

misreporting of naphtha as naphthalene or MTVLO tank mislocation errors in the 2005 NEI. If 

this is the case, we recommend that EPA make those corrections and re-calculate MTVLO 

source and facility-wide risk. This should result in the facility no longer being listed as having a 

cancer MIR greater than 1 in a million. Going forward, the corrected data should be 

incorporated in the 2005 NEI and subsequent versions of that database.

TX Petrochemicals – Houston, Texas. As shown in Figure 3, a number of sources at the 

TPC facility have incorrect latitude/longitude coordinates in the 2005 NEI that mislocate them 

offsite, close to or in residential neighborhoods. Such source mislocations caused EPA to 

overestimate the facility-wide cancer MIR to be 200 in a million. That this is so was confirmed 

by ENVIRON risk analyses in which the same facility-wide cancer MIR was calculated as EPA 

when the incorrect 2005 NEI source location data were modeled.

EPA calculated the cancer MIR for MTVLO sources at the TPC facility to be 20 in a 

million. ENVIRON’s risk analyses, however, did not calculate the same value as EPA. Instead, 

ENVIRON calculated the cancer MIR for MTVLO sources (as shown in Figure 4, 2005 NEI 

emission release points 70 and 218) to be 0.23 in a million, below the cancer risk de minimis

level of 1 in a million. 

We were not able to determine why the two risk estimates are so different (nearly two 

orders of magnitude). Note that Figure 4 shows the locations of MTVLO sources to be more 

than a mile and a half to the north northeast of the main portion of the TPC facility, and farther 

away from residential areas. To resolve this difference in risk estimates, we recommend that 

EPA re-examine its identification of MTVLO sources and confirm their list of those source with 

facility staff. Should the list of MTVLO sources need to be revised, we further recommend that 

EPA modify its list of MTVLO sources and re-calculate MTVLO source cancer MIR.

After consultation with facility staff and review of a facility plot plan, we determined that 

a systematic coordinate system translation error may have been responsible for source location 

errors in the 2005 NEI. That translation error was initially found by shifting the location of a 

large flare, whose location could be clearly discerned in an aerial photograph. When shifted 

about 204 meters almost due north (toward an azimuth angle of 355 degrees), the 2005 NEI 

location of that flare, shown in Figure 3 and labeled as emission release point ID 51, coincided 

with the location shown in the aerial photograph. A shift in incorrect 2005 NEI locations by the 

same amount aligned other sources with their correct locations as shown on the facility plot plan. 

In addition, a number of voluntary emission reduction measures have been taken by TPC 

that have substantially lowered facility emissions since 2005. According to TPC (2010b), in 

2005, TPC entered into a voluntary emission reduction agreement (VERA) with the Texas 

Commission on Environmental Quality (TCEQ) and a settlement agreement with the City of 

Houston. From 2004 to 2008, TPC states that 1,3-butadiene emissions have been reduced by 

over 75 percent. TPC further states that, in 2009, it entered into a second agreement with TCEQ 

providing for additional emission reductions, and in 2009 and 2010, reduced the allowable 1,3-

butadiene emissions authorized by its permit to make those emission reductions permanent.
Copyrighted page/s removed. Copyrighted 

material is not available in Regulations.gov since 

it may not be reproduced without consent of the 

copyright holder. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 202-566-1744 

Fax: 202-566-9744 

Email: docket-customerservice@epa.gov
ENVIRON memo

22

Risk was re-calculated using corrected source locations and 2009 facility emissions. The 

cancer MIR for MTVLO sources was reduced to 0.19 in a million, below the cancer risk de minimis

level of 1 in a million. Facility-wide cancer MIR, originally estimated by EPA to be 200 in a 

million, was reduced more than a factor of two below 100 in a million.

KinderMorgan – Galena Park, Texas. A large number of emission sources at the KM facility 

in Galena Park are represented in the 2005 NEI as being collocated at a single latitude/longitude 

location. Those sources are denoted in Figure 5 by lines originating from that single collocation 

point, which is located offsite, in the middle of Clinton Drive, just to the north of a group of tanks.

The facility has updated numerous errors found in the 2005 NEI. Source latitude/longitude 

coordinates were replaced with locations provided by TCEQ, and emissions data for a subset of 

sources were revised to correct anomalies regarding product speciation and tank roof landing loss 

emission estimation methodology. 

Kinder Morgan’s review has confirmed that, when the data are revised to reflect more 

accurate HAP emission rates and source locations, the facility-wide MIR estimate is reduced to 

below one hundred in a million by a wide margin. Further, the actual 2005 MIR is expected to be 

even lower, given that only the more substantive emissions estimation over reporting anomalies have 

been revised.

More importantly, since 2005 Kinder Morgan has implemented many operational work 

practices and installed engineering controls that have significantly reduced facility-wide HAP 

emissions. For example, 1,3-butadiene emissions were reduced by 97% from the revised 2005 

emission estimates to 2009, from 48.79 tpy to 1.40 tpy. In addition, 2009 benzene emissions were 

reduced by 89% compared to the revised 2005 emissions, from 77.04 tpy to 8.29 tpy. 

In summary, data errors were present in the 2005 NEI that caused EPA to overestimate 

cancer MIR for all of the facilities for which EPA calculated an MTVLO cancer MIR greater than 1 

in a million. All four of these facilities had significant source location errors. Additionally, one of 

the facilities mistakenly reported naphtha emissions as naphthalene because of incorrect VOC 

speciation, and at least two, and possibly all, may have had significant reductions in emissions since 

2005. 

After correction of these data errors, re-calculated risk is reduced significantly lower than 

calculated by EPA. Only one of the 152 facilities modeled by EPA would have a re-calculated 

cancer MIR from MTVLO sources greater than 1 in a million, instead of three, and none of the these 

facilities would have a facility-wide risk greater than 100 in a million, instead of two.
Copyrighted page/s removed. Copyrighted 

material is not available in Regulations.gov since 

it may not be reproduced without consent of the 

copyright holder. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 202-566-1744 

Fax: 202-566-9744 

Email: docket-customerservice@epa.gov
ENVIRON memo

24

B. CHANGES IN THE PROTOCOL FOR DETERMINING RESIDUAL RISK

In the residual risk analyses accompanying the proposed RTR rule, EPA has materially 

changed its previous protocol for determining residual risk. In particular, EPA has included:

Calculation of facility-wide risks, in addition to risks from sources in the specific MACT 

category under consideration

Calculation of risks associated with MACT-allowable emissions, in addition to risks 

from actual emissions

Demographic analysis of risks across different social, demographic, and economic 

groups in the populations living nearby.

These changes appear to be an effort by EPA to implement recommendations of the Risk 

and Technology Review (RTR) Methods Panel of EPA’s Science Advisory Board (SAB 2009). 

This SAB panel was asked by EPA’s Office of Air Quality Planning and Standards to review and 

provide comment on the methodologies by which EPA was conducting RTR residual risk 

assessments.

EPA states that it is ―considering all of this available health information to inform our 

determination of risk acceptability and ample margin of safety under CAA section 112(f).‖ It is not 

clear what relative weight is accorded by EPA to each of the various metrics used to characterize 

risk, and particularly how judgments about risk acceptability and ample margin of safety are 

affected by the addition of facility-wide risk, MACT-allowable risk, and environmental justicemotivated demographic analyses. EPA states its belief that ―the relative weight of the many factors 

that can be considered in selecting an ample margin of safety can only be determined for each 

specific source category.‖

 

Comments about the above new additions to EPA’s residual risk assessment protocol 

include the following:

Facility-wide risk. Section 112(f) of the Clean Air Act appears to apply a source category, 

not the entire facility: 

“...the Administrator shall...promulgate [residual risk] standards for such [source]

category or subcategory if promulgation of such standards is required in order to 

provide an ample margin of safety to protect public health...”

A plain reading of the statute, and its interpretation historically by EPA in previous residual risk 

assessments, suggests that Congress intended residual risk rulemaking to be based on categoryspecific risk, and not facility-wide. Thus, EPA’s justification for including facility-wide risk in 

RTR rulemaking seems tenuous, and likely based on a generalized notion of ―ample margin of 

safety.‖ For MTVLO sources, EPA does not appear to use facility-wide risk as an explicit criteria 

in judging risk acceptability.
ENVIRON memo

25

MACT-allowable emissions. Previously, API offered comments on the SAB panel’s review 

and recommendations (API 2010b). As noted in those comments, EPA’s continued reliance on risk 

based on actual emissions seems warranted for reasons that include the following:

1. Use of actual emissions as the basis for RTR residual risk assessments is more consistent 

with:

(a) The residual risk language of the Clean Air Act,

(b) Risk assessment practice elsewhere at EPA and other agencies, and 

(c) The actual-emission basis of such important regulatory tools as the National 

Emission Inventory (NEI), the National Air Toxics Assessment (NATA), the Toxic 

Release Inventory (TRI) program, and state and local agency air toxics emission 

inventory and risk assessment programs (such as California’s Air Toxics Hot Spots 

Program). 

2. Even though based on actual emissions, RTR residual risk assessments contain a large 

margin of high-side conservatism by assuming, for example, that exposures to the public 

occur continuously, each hour of every day for a 70-year lifetime, while outdoors and 

remaining fixed at the same residence, without moving residences or traveling during the 

day to work, school, or for other purposes.

3. Risk estimates based on actual emissions provide more realistic and reliable information 

to decision makers and the public about actual risks because they are more representative 

of physical conditions that may actually occur.

4. Reliance on actual emissions better recognizes that, in the case of large, complex, and 

integrated facilities, it is not physically possible for equipment to operate simultaneously 

at maximum allowable levels, even for short periods of time, let alone for an entire 

lifetime as assumed by EPA in calculating cancer risks.

For the MTVLO source category, EPA statements in the proposed rule and supporting 

material appear contradictory. In the summary of residual risk assessment results in the proposed 

rule, EPA states that it assumed that MACT-allowable emissions were 3 times greater than actual 

emissions:

“...the highest factor for one of these facilities [having an MTVLO cancer MIR 

greater than 1 in a million] was 3.0, based on the ability of these facilities to achieve 

98-percent control of emissions where only 97-percent emission control is required 

by the MACT standards for another facility, they could, under MACT, increase 

emissions by a factor of 3.”

The basis for this calculation is not clear. Suppose a facility achieved 98% control, while 

the MACT required only 97% control. If the facility relaxed its controls to the 97% required by the 
ENVIRON memo

26

MACT, emissions would increase by 3%/2%, or a factor of 1.5, not 3. This factor of 1.5 is used 

elsewhere in EPA’s risk summary (EPA 2010b) and forms a basis of the Risk Acceptability 

discussion in the proposed rule (p. 65114). We recommend that EPA review its calculation of the 

MACT-allowable scaleup factor for MTVLO sources, and then use a consistent value throughout 

the proposed rule and supporting material.

In any event, risk estimated using MACT-allowable emissions seems hypothetical and 

unrealistic. If a facility has already installed control equipment that exceeds control requirements 

under the MACT, it seems highly unlikely that the facility would remove that better-performing 

control equipment to install less-effective MACT-compliant equipment, even if theoretically 

allowed. Thus, risk estimates based on MACT-allowable emissions may have little practical 

relevance in RTR rulemaking.

Demographic analyses. As with facility-wide risk, demographic analyses do not have an 

explicit statutory basis as a formal criterion in setting residual risk standards. Under Section 

112(f)(2) of the Clean Air Act, residual risk standards must be set:

“If [MACT] standards...applicable to a category or subcategory of sources...do not 

reduce lifetime excess cancer risk to the individual most exposed to emissions from a 

source in the category or subcategory to less in one in a million, the Administrator 

shall promulgate standards...”

The decision whether or not to set residual risk standards, then, is based on risk to the 

―individual most exposed,‖ not the demographic distribution of risk. The statutory basis for the use 

of such demographic analysis and how they are to be interpreted needs further clarification and 

justification.

C. REFERENCES

API. 2010a. Letter to Stephen A. Shedd, EPA, from Matthew A. Todd, API, entitled ―Ongoing 

API Work to Review and Correct As Necessary Data on Four Marine Vessel Loading 

Facilities.‖ American Petroleum Institute, Washington, D.C. August 16.

API. 2010b. Letter to Dr. Sue Shallal, EPA, from Matthew A. Todd, API, entitled ―Comments on 

Draft Report of SAB’s Risk and Technology Review Methods Panel.‖ American Petroleum 

Institute, Washington, D.C. March 17.

Chevron. 2010. Email to Karen Shaffner, EPA, from Michelle Herman, Chevron Pipe Line 

Company. EPA-HQ-OAR-2010-0600-0042. July 6.

EPA. 2010a. ―National Emission Standards for Hazardous Air Pollutant Emissions: Hard and 

Decorative Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers 

and Resins; Marine Tank Vessel Loading Operations; Pharmaceuti9cals Production; The 

Printing and Publishing Industry; and Steel Pickling—HCl Process Facilities and 

Hydrochloric Acid Regeneration Plants; Proposed Rule.‖ U.S. Environmental Protection 
ENVIRON memo

27

Agency, published in Federal Register, Vol. 74, No. 203, p. 65068. EPA-HQ-OAR-0600-

0001. October 31.

EPA. 2010b. ―Table 1 – Risk Assessment Results.‖ EPA-HQ-OAR-2010-0600-0243.1. U.S. 

Environmental Protection Agency.

EPA. 2010c. ―Appendix 6, Detailed Risk Modeling Results.‖ EPA-HQ-OAR-2010-0600-0190.3. 

U.S. Environmental Protection Agency.

EPA. 2010d. Telephone Contact Summary – 0210426.004.05, Conference Call Between EPA and 

API. EPA-HQ-OAR-2010-0600-0027. August 16.

SAB. 2009. ―Draft Report of the Risk and Technology Review Methods Panel.‖ EPA Science 

Advisory Board, U.S. Environmental Protection Agency, Washington, D.C. December 3.

TPC. 2010a. Email to Karen Shaffner, EPA, from James Scroggins, TPC Group. EPA-HQ-OAR2010-0600-0037. June 3.

TPC. 2010b. Letter to Mr. Stephen Shedd, EPA, from Marise Lada Textor, TPC Group. EPAOAR-2010-0600-0063. September 3.
28

ATTACHMENT 2 – HAP Emissions per Million Gallons of Gasoline Loaded

The estimated HAP emissions per million barrels per year (M bbl/yr) of gasoline loaded depends upon the 

assumed concentration of volatile organic compound (VOC) vapors in the air/vapor mixture displaced from 

the cargo compartments, and the concentration of HAP constituents in that vapor.

VOC emission factors. Emission factors for the loading of gasoline at marine terminals are given in Table 

5.2-2 of EPA’s AP-42 document. These values range from 0.7 pounds of VOCs per thousand gallons loaded 

(lbs/103gal) to 3.9 lbs/103gal, depending upon the size of the vessel and the prior condition of the cargo 

compartment. The value that would result in the highest emissions estimate, then, would be 3.9 lbs/103gal.

HAP content. EPA recommends, in paragraph 7.1.4 of AP-42, the application of Raoult’s Law to determine

the HAP content in the vapor phase of a hydrocarbon mixture from the HAP content in the liquid phase of 

that mixture. Typical HAP concentrations in the liquid phase of normal gasoline may be obtained from 

EPA’s TANKS software program (similar concentrations are given in EPA’s EPCRA Section 313 Industry 

Guidance, Petroleum Terminals and Bulk Storage Facilities, EPA 745-B-00-002, February 2000). The use 

of MTBE in motor gasoline has been phased out in the United States, and thus the concentration of MTBE 

should be given as 0%. Using typical values for the properties of gasoline and a temperature of 60oF, the 

determination of vapor phase concentrations by Raoult’s Law is illustrated in the following table:

RVP Ml A B Pva (psia) Mv

Gasoline 10 92 11.724 5237.273 5.19 66

temp(F) 60 Yi ( Mi / Mvt )

liquid liquid phase liquid temp(C) 15.6 vapor partial vapor HAP/VOC

phase molecular wt. phase pressure pressure phase vapor phase

Wi Mi Xi Antoine's Constants (deg.C) Pi* Pi Yi Zi

Species: {wt percent} {lb/lb-mole} {mole frac.} A B C vapor pressure {psia} {mole frac.} {wt percent}

n-hexane 1.0% 86.18 0.011 6.878 1171.5 224.37 1.9126 0.0204 0.0039 0.51%

benzene 1.8% 78.11 0.021 6.906 1211 220.79 1.1709 0.0248 0.0048 0.57%

iso-octane 4.0% 114.23 0.032 6.812 1257.8 220.74 0.5962 0.0192 0.0037 0.64%

toluene 7.0% 92.14 0.070 7.017 1377.6 222.64 0.3311 0.0231 0.0045 0.62%

ethylbenzene 1.4% 106.17 0.012 6.950 1419.3 212.61 0.1037 0.0013 0.0002 0.04%

xylene (-m) 7.0% 106.17 0.061 7.009 1462.3 215.11 0.0903 0.0055 0.0011 0.17%

cumene 0.5% 120.19 0.004 6.929 1455.8 207.20 0.0479 0.0002 0.0000 0.01%

MTBE 0.0% 88.15 0 6.872 1116.8 224.74 3.2415 0.0000 0.0000 0.00%

naphthalene 0.0% 128.17 0 7.146 1831.6 211.82 0.0024 0.0000 0.0000 0.00%

22.7% = sum of HAP in the liquid sum of HAP in the vapor = 2.56%

This analysis is conservative, in that it uses a benzene concentration of 1.8%, whereas actual benzene 

concentrations in gasoline in the United States has been driven down to the range of 0.5-0.6% by EPA’s 

Fuels Specifications. Nevertheless, the HAP concentration in the vapor phase will be rounded up to 3% for 

purposes of this illustration.
29

From the conservative values given above, HAP emissions from the loading of gasoline into marine vessels 

may be estimated as follows:

(3.9 lbs VOC/103gal) x (3% HAP) = 0.12 lbs HAP / 103gal 

= 120 lbs HAP / 106gal 

= 5,040 lbs HAP / 106bbl 

= 2.5 tons HAP / M bbl

The volume of gasoline that would have to be loaded in order to emit 25 tons per year of HAP, then, is 10 M 

bbl/yr. And, again, this is based on conservative assumptions. It is, therefore, unlikely that the loading of 

less than 10 M bbl/yr of gasoline into marine vessels would trigger a HAP major source status (i.e., more 

than 25 tons per year of HAP emissions).
ExxonMobil Chemical Company 

Safety, Security , Health and Environment 

13501 Katy Freeway 

Houston, TX 77079-1398 

 

December 6, 2010 

Comments on EPA’s Proposed Rule: 

NESHAP for Group I Polymers and Resins; 

Residual Risk and Technology Reviews 

75 Fed. Reg. 65068 (October 21, 2010) 

 

Via Electronic Filing: a-and-r-docket@epa.gov

EPA Docket Center, EPA West (Air Docket) 

U.S. Environmental Protection Agency 

Mailcode: 2822T 

1200 Pennsylvania Ave., NW 

Washington, DC 20460 

Attention: Docket ID No. EPA-HQ-OAR-2010-0600

Dear Sir or Madam: 

ExxonMobil appreciates the opportunity to submit comments on the Environmental 

Protection Agency's (EPA or the Agency) October 21, 2010 proposed rule on “National 

Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative 

Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers and 

Resins; Marine Tank Vessel Loading Operations: Pharmaceuticals Production; The 

Printing and Publishing Industry; and Steel Pickling-HCl Process Facilities and 

Hydrochloric Acid Regeneration Plants”. Our comments focus on the Group I Polymers 

and Resins NESHAP (P&R1) source category requirements as well as the policy issues 

relating to residual risk and technology reviews that were included in the preamble. 

ExxonMobil is a major integrated energy company with exploration, production, refining, 

transportation, marketing and chemical operations. The proposed rule will apply to four 

ExxonMobil units at three facilities in Louisiana and Texas and will have a potentially 

substantive impact on three of the units. These facilities are in the Butyl Rubber and 

Ethylene Propylene Rubber (EPR) source categories. In addition, the policy issues 

included in the preamble will impact other ExxonMobil facilities that will be affected by 

future rulemakings related to the residual risk and technology reviews. 

ExxonMobil has also been involved in the development of comments from other trade 

organizations, including: 

• International Institute of Synthetic Rubber Producers, Inc. (IISRP) 

• Residual Risk Coalition 

• American Petroleum Institute (including comments on the Marine Tank Vessel 

Loading Operations NESHAP) 
2

We incorporate comments from these organizations into ExxonMobil comments by 

reference. 

Our key comments on the proposed rule are summarized as follows: 

Basis for rulemaking

• Requiring the installation of additional emission controls, where the Agency has 

already determined that source emissions are at an acceptable risk level, is not 

sound regulatory policy. 

• EPA is without authority to impose new standards under Clean Air Act §§ 112(d)(2) 

and (d)(3) for emission sources in source categories for which a MACT standard 

already has been promulgated – § 112(d)(6) provides the Agency’s only authority to 

adjust existing MACT standards. 

• EPA already made the decision that beyond-the-floor controls were not costeffective in the 1996 rulemaking. EPA has no authority and no grounds to perform a 

second § 112(d)(2) analysis and has provided no rationale as to why that analysis is 

deficient or no longer applicable. 

• EPA does not have the legal authority to justify beyond-the-floor controls in one 

source category by combining the source category with controls that are calculated 

to be cost-effective for another source category. Decisions are made on a source 

category by source category basis. 

• EPA’s analysis, based on combining the Butyl Rubber (Halobutyl subcategory) and 

EPR source categories to justify beyond-the- floor front-end controls, is inconsistent 

with maintaining facility operating flexibility and how controls would be implemented. 

Establishing emission standards

• EPA’s proposed emission limits for back-end Baton Rouge Halobutyl Rubber and 

Baytown Butyl Rubber process vents require further modification to reflect actual 

emissions performance and variability. 

• EPA must recognize that maintenance of regenerative thermal oxidizers (RTOs) is 

required to achieve 98% organic HAP destruction. 

• The proposed front-end beyond-the-floor controls for Baton Rouge Halobutyl 

Rubber, Baton Rouge EPR, and Baytown Butyl Rubber are not cost-effective and 

should not be finalized. EPA significantly underestimated the cost of controls. 

• The proposed back-end beyond-the-floor controls for Baytown Butyl Rubber are not 

cost-effective, and a further analysis of back-end beyond-the-floor controls for Baton 

Rouge Halobutyl Rubber confirms EPA’s decision to not require additional controls. 

EPA significantly underestimated the cost of controls. 
3

• The Butyl Rubber source category subcategories should be redefined to reflect the 

current process differences. 

• EPA needs to clarify the definition of back-end process vents to avoid confusion and 

to remove operations that are already regulated under P&R1 (40 CFR part 63 

subpart U). 

• EPA should revise the proposed rule to remove the requirement for halogen control 

for Group 2 continuous front-end process vents. 

Compliance/other

• EPA should provide 4 years to comply with emission limits that require capital 

investment to install controls; the automatic one-year extension should be 

incorporated into the final rule. EPA should also allow four years for compliance 

even when the emission limit for the floor is based on current operation and no 

beyond-the floor controls were proposed. 

• EPA should clarify, in the absence of allowing four years as recommended above, 

that for emission limits not requiring controls the first compliance demonstration is 2 

years (24 months) following the date of the final rule. 

• Since there is no consent decree deadline for finalizing any rule related to the Butyl 

Rubber and EPR source categories, EPA should take the appropriate time to 

thoroughly review the comments submitted and reassess the cost-effectiveness 

determinations. 

Startup/Shutdown/Malfunction (SSM) provisions

• EPA has misread the Sierra Club v. EPA court decision, which does not require the 

imposition of a single emission standard to all emissions; the decision merely 

requires that some standard to limit emissions applies at all times. 

• EPA should propose a separate emission limit or apply work practice standards 

during periods of SSM to appropriately recognize the operating and emission 

differences during these periods. 

• The proposed affirmative defense is not a substitute for setting emission standards 

for SSM periods. 

• The proposed affirmative defense as written is unreasonable and impracticable. 

Residual Risk and Technology Reviews

• ExxonMobil supports EPA’s conclusion that no further residual risk (§ 112(f)) or 

technology review (§ 112(d)(6)) is required for the Butyl Rubber and EPR source 

categories; the previously finalized analysis reached the appropriate conclusion. 
4

• EPA’s risk analysis for the Butyl Rubber and EPR source categories indicates that 

all facilities are low risk; EPA should delist the Butyl Rubber and EPR source 

categories under § 112(c)(9) and has the legal authority to do so. 

• On residual risk and technology review policy and future rulemaking: 

o Continuing implementation of residual risk and technology reviews should be 

consistent with the HON court decision. 

o Risk assessments should be based on source category actual emissions. 

o EPA should not expand the health information metrics beyond those already 

evaluated. 

o In addition to the health risk metrics already established, EPA should include 

central tendency or most expected risk to better communicate the conservative 

nature of EPA risk assessments. 

o Residual risk under § 112(f)(2) should inform the § 112(d)(6) technology review 

decision; a review under § 112(d)(6) is not required if the post-MACT emission 

levels result in risks that are deemed to be protective of public health with an 

ample margin of safety. 

Attached are our detailed comments. In addition, ExxonMobil is separately submitting 

additional process and cost information under a claim of Confidential Business 

Information. This information provides additional support to the attached comments and 

is referenced as the “CBI letter”. 

Respectfully submitted, 

Robert J. Morehouse 

Downstream and Chemical SH&E 

Attachment 

cc: Ms. Mary Tom Kissell 

Sector Policies and Programs Division (E143-01) 

Office of Air Quality Planning and Standards 

 U.S. Environmental Protection Agency 

 Research Triangle Park, NC 27711 

 Mr. Randy McDonald 

Sector Policies and Programs Division (E143-01) 

Office of Air Quality Planning and Standards 

Environmental Protection Agency 

Research Triangle Park, NC 27711 

Attn: Desk Officer for EPA 

Office of Information and Regulatory Affairs 

Office of Management and Budget (OMB) 

725 17th Street, NW. 

Washington, DC 20503 
5

Table of Contents 

ExxonMobil Comments on EPA’s Proposed Rule on National 

Emission Standards for Hazardous Air Pollutants - Group I Polymers 

and Resins; Residual Risk and Technology Reviews

 I. Background On ExxonMobil Businesses Impacted By The Proposed Rule.........1

 II. Source Category And Subcategory Issues...................................................................3

III. Applicability Issues .............................................................................................................5

IV. Basis for Establishing the Floor and the Proposed Emission Limitations..............8

 V. Basis for Beyond-The-Floor Decisions ........................................................................ 16

VI. Emission Control Cost ..................................................................................................... 28

VII. Compliance Time.............................................................................................................. 39

VIII. Startup/Shutdown/Malfunction and Affirmative Defense ......................................... 41

 IX. Other Comments and Edits ............................................................................................ 54

 X. Residual Risk and Technology Review: Butyl Rubber And EPR Source 

Categories .......................................................................................................................... 58

XI. EPA Policy On Residual Risk And Technology Reviews ........................................ 62
1

ExxonMobil Comments on EPA’s Proposed Rule on National 

Emission Standards for Hazardous Air Pollutants - Group I Polymers 

and Resins; Residual Risk and Technology Reviews

October 21, 2010 

75 Fed. Reg. 65068 

 

I. Background on ExxonMobil Businesses Impacted by the Proposed Rule 

ExxonMobil Chemical is a major petrochemical company with manufacturing, 

technology and marketing operations around the world. The company’s broad range 

of petrochemical and polymer products provide the building blocks for a wide range of 

products, ranging from packaging materials and plastic bottles to automobile 

bumpers, synthetic rubber, solvents and countless consumer goods. Major 

petrochemical products include: polyethylene, polypropylene, Butyl polymers, polymer 

modifiers, specialty elastomers, tackifying resins, hydrocarbon and oxygenated fluids, 

plasticizers, synthetic fluids and lubricant basestocks, chemical intermediates, and 

films. 

 ExxonMobil, like other companies, manages product lines as separate businesses. 

The individual businesses develop strategies, product plans, and investment plans, 

and each business is responsible for the financial stewardship of costs and 

profitability. A key activity is to assess cost-competitiveness as our major businesses 

have worldwide competition. Adding significant capital cost to U.S. businesses, with 

no investment return, reduces international competitiveness. 

A. Butyl Rubber 

ExxonMobil Chemical has been at the forefront of technology and innovation in the 

rubber industry since inventing and patenting Butyl rubber in 1937. The company 

markets high-quality synthetic rubber worldwide and is a global leader in Butyl 

technology, services and products for tires and other rubber products. 

Butyl rubber is a worldwide business. ExxonMobil has manufacturing facilities in 

the U.S. (Baton Rouge, Louisiana and Baytown, Texas), Europe (Fawley, England 

and Notre-Dame-de-Gravenchon, France) and recently completed an expansion at 

an affiliate in Kawasaki, Japan. Major industry competitors include: Lanxess 

(Sarnia, Canada and Antwerp, Belgium) and Yanshan, an affiliate of Sinopec. 

Butyl rubber demand is driven by growth in tire demand, which in turn is driven by 

growth in personal and commercial vehicles, primarily in the developing economies 

of the world. Growth has been, and is expected to continue, in excess of 4% per 

year, with the majority of the growth in Asia and in particular China. This has led to 

the emergence of new entrants into the Butyl business located in China, placing 

added cost competitiveness challenges to suppliers located in the U.S. and 

Europe. 
2

B. Ethylene Propylene Rubber (EPR) 

ExxonMobil is a major producer of ethylene propylene rubber products, including 

VistalonTM ethylene propylene diene (EPDM) rubber manufactured in Baton 

Rouge, Louisiana, based on proprietary Ziegler-Natta catalysis technology. Since 

2004 ExxonMobil has been producing VistalonTM EPDM rubber at an additional 

location in Baton Rouge in a flexible asset based on proprietary ExxpolTM 

metallocene technology, together with VistamaxxTM propylene-based elastomers 

(for use in compounding and polymer modification, films and non-woven 

applications), and ExactTM Plastomers (for use in compounding and polymer 

modification applications). VistalonTM EPDM rubber is used in a wide variety of 

applications including: automotive (hoses, belts, weatherseals, gaskets), 

construction (roof sheeting, glazing seals, and wire and cable insulation), and 

durable goods (hoses and gaskets). 

EPR is also a worldwide business. Product demand is driven by the growth in 

automotive, construction and durable goods, primarily in the developing economies 

of the world. Growth has been, and is expected to continue, in excess of 3% per 

year, with the majority of the growth in Asia and in particular China. This has led to 

significant new business investments, primarily in Asia (Singapore, China, Korea). 

Geographic changes in the automotive and durable goods industries have also led 

to a significant increase of inter-regional trade for EPR. 

Demand in the Americas is not projected to meet the 2007 level until 2013, and in 

Europe until 2015, requiring U.S and Europe-based producers to be costcompetitive in the fast growing markets in Asia. Recent and announced future 

cost-competitive assets in emerging regions are expected to make significant 

inroads in the more mature regions of Europe and North America, placing added 

cost competitiveness challenges to supply sources located in the U.S. and Europe, 

and particularly those based on older non-metallocene technology. Over the last 

ten years industry has faced significant restructuring resulting from the deployment 

of cost-competitive metallocene-based technology and the emergence of new 

players, particularly in Asia. 

Other U.S. producers include Dow Chemical (Louisiana), Lion Copolymer 

(Louisiana) and Lanxess (Texas). In recent years, the number of U.S. producing 

sites has declined from 7 to 5 with the closure of assets by DSM (Louisiana) and 

Dow Chemical (Texas). 

Outside the U.S., ExxonMobil has EPR facilities in France. Worldwide competitors 

include: DSM (Brazil and the Netherlands), Lanxess (Germany), Polimeri Europa 

(Italy), Mitsui Chemicals (Japan, Singapore), JSR Corporation (Japan), Kumho 

Polychem Co and SK Energy Co. (Korea), Nizhnekamskneftekhim (Russia) and 

Jilin (China). In recent years, assets were shutdown by DSM (Japan), Mitsui 

Chemicals (Japan) and Herdillia (India). 
3

II. Source Category and Subcategory Issues 

A. ExxonMobil has an EPR facility at the Baton Rouge Plastics Plant. 

 

As noted in our comments dated February 8, 2008 on the December 12, 2007 

residual risk and technology review proposed rule covering the Polymer and 

Resins 1 (P&R1) source category, and other communications to EPA, 

ExxonMobil started up an EPR facility in 2004 at the ExxonMobil Baton Rouge 

Plastics Plant. 72 Fed. Reg. 70543. This EPR unit, identified as Line G, is a new 

source under the Polymers and Resins 1 NESHAP (P&R1), 40 CFR part 63, 

subpart U. The current proposal reports that there are three existing sources in 

the EPR source category, including the ExxonMobil Chemical unit at the Baton 

Rouge Chemical Plant, but the ExxonMobil Baton Rouge Plastics Plant unit is not 

included in that count. 

As for the two non-ExxonMobil EPR processes identified as being in the EPR 

source category, Line G does not have halogenated front-end process vents that 

result in HCl emissions. Thus, the current proposal and the supporting analyses 

are not impacted by the inclusion of Line G in the EPR source category. 

B. The Butyl Rubber source category subcategories have changed since 

subpart U was promulgated. 

In the original 1996 subpart U rulemaking, EPA recognized the significant 

differences between the ExxonMobil Baton Rouge and Baytown Butyl Rubber 

facilities and therefore subdivided the Butyl Rubber source category into “Butyl” 

and “Halobutyl” subcategories. EPA explained the decision to establish separate 

subcategories as follows:

The Butyl rubber source category was divided into subcategories for 

production of Butyl rubber and production of Halobutyl rubber, because of 

variations in both the production process and the HAP emitted. While the 

initial portion of the production processes are similar, the Halobutyl rubber 

process contains two additional unique production steps. In these additional 

steps additional HAP are used and are also, therefore, emitted. [Hazardous 

Air Pollutant Emissions from Process Units in the Elastomer Manufacturing 

Industry, Basis and Purpose Document for Proposed Standards, EPA 453/R95-006a, May 1995, p. 4-1] 

In the last 15 years there have been a number of projects at the Baton Rouge 

and Baytown facilities to adjust product mix, increase capacity, provide operating 

flexibility, and improve process efficiency. As a net result of these changes, the 

Baytown Butyl Unit now produces more Halobutyl elastomers than Butyl 

elastomers. There remain, however, basic differences between the processes at 

the two sites that warrant continuing segregation into two separate 

subcategories. We discuss the process differences in our CBI letter. 
4

C. The Butyl Rubber source category subcategories should be redefined to 

reflect the current process differences. 

The proposal and the supporting analyses treat the Baytown Butyl unit as 

belonging to the “Butyl” subcategory and the Baton Rouge Butyl unit as belonging 

to the “Halobutyl” subcategory. While these were the appropriate assignments 

when the P&R1 rule was originally finalized, the Baytown unit now produces three 

major products with the primary elastomer product (as defined in subpart U) being 

Halobutyl Rubber, both on a mass of elastomer produced basis and an operating 

time basis. Thus, under the current Butyl Rubber source category subcategory 

definitions in subpart U, both units would be considered part of the Halobutyl 

subcategory and there would be no units in the Butyl subcategory. However, there 

are significant differences between the two units, making it clear that they should 

remain in separate subcategories. 

EPA should modify the subpart U criteria for determining subcategory applicability 

under the Butyl Rubber source category. Currently, subcategory assignment is 

based on the primary product of the Elastomer Unit. However, it is the process 

flexibility, even if the flexibility is applied to products that are not the primary 

product which drives process and emission differences. For instance, back-end 

hazardous air pollutant (HAP) emissions on a pounds per ton of product basis for 

our Baton Rouge Butyl Unit are significantly lower than the HAP emissions for our 

Baytown Butyl Unit because the latter unit is a flexible operations unit and its HAP 

emissions are set by the conditions associated with a product that is not the 

primary product. We would therefore recommend that the Butyl subcategory 

descriptions be modified to distinguish Halobutyl-only production and flexible 

product production and that the primary product determination only be applied to 

facilities at the source category level, not at the subcategory level. 

D. Combining the two ExxonMobil Butyl units into the same subcategory is not 

a logical outgrowth of the proposal and would require new beyond the floor 

analyses and a new proposal. 

If these two units were considered part of the same subcategory, the current 

proposal and its supporting analyses would not be applicable and new analyses 

and a new proposal would be required. On the other hand, minor revision of the 

subcategory definitions would be a logical outgrowth of the proposal and the 

comments received and thus the Agency could proceed with evaluating the 

comments and promulgating a final rule. 

Under the current proposal, halogen control of the halogenated continuous frontend process vents for both the Butyl and Halobutyl subcategories would be 

required1

. Having the two units in the same subcategory would preclude reaching 

 

1

 As EPA explains in the proposal, the floor for front-end process vents for both subcategories and, thus both Butyl 

units, was established in the 1996 rulemaking as 98% control of organic HAP. Thus, new floor analyses are not 

needed whether or not the two Butyl source category subcategories are combined. 
5

different beyond-the-floor decisions for each unit, a possibility given the costeffectiveness differences of controlling the HCl emissions from each site. 

For back-end process operations, it is proposed to require control of the currently 

uncontrolled process vents at the Baytown Butyl unit and not to require control of 

the currently uncontrolled process vents at the Baton Rouge Butyl unit, as beyondthe-floor steps, based on the calculated cost-effectiveness for these operations. 

With these units in the same subcategory, the Agency would need to consider 

cost-effectiveness on a total subcategory basis. Using the EPA emission and 

cost-effectiveness estimates for each unit provided in the proposal and combining 

them on an emissions-weighted basis yields a combined cost effectiveness of 

approximately $30,000/ton of organic HAP. The Agency has clearly indicated in 

this2 and previous rulemakings3

 that they do not consider $30,000 per ton to be 

cost-effective for beyond-the-floor HAP reduction options and we certainly concur. 

A further discussion of cost-effectiveness is included in Section V. 

 

III. Applicability Issues 

A. EPA needs to clarify the definition of back-end process to avoid confusion 

and to remove operations that are already regulated under subpart U. 

It is proposed to establish numeric emission limits for Butyl and Halobutyl back-end 

operations. Compliance is to be demonstrated by estimating emissions from those 

operations on a rolling 12-month basis. The definition of “back-end” in subpart U is 

“the unit operations in an EPPU following the stripping operations. Back-end 

process operations include, but are not limited to, filtering, coagulation, blending, 

concentration, drying, separating, and other finishing operations, as well as latex 

and crumb storage.” 40 CFR 63.482. This definition is broad and would appear to 

include operations that have no HAP emissions potential and/or which are usually 

remote from the process operation (e.g., bale warehousing and truck and rail 

loading). Since there are no HAP emissions from handling finished product (Butyl 

and Halobutyl elastomers are gas impermeable and, if there is any small amount of 

residual HAP present in the finished product, that HAP would not diffuse through 

the elastomer and would not be released during final product handling) it would be 

helpful for the Agency to clarify that such operations need not be considered when 

estimating emissions for compliance purposes. This would also make the backend definition and compliance requirements consistent with the data collected on 

these emissions during the information collection request (ICR) process. 

 

2

 At 75 Fed. Reg. 65099 (October 21, 2010), relative to controlling back-end Epichlorohydrin vents for organic HAPs 

(a parallel situation to the Halobutyl proposal), it is stated that “We estimate that an incinerator would achieve an 

emissions reduction of 98 percent, resulting in a HAP decrease of approximately 35 TPY, with a cost effectiveness of 

approximately $31,000/ton. ... We believe that the costs and other impacts of this beyond-the-floor option are not 

reasonable, given the level of emission reduction. Therefore, we are proposing an emission standard that reflects the 

MACT floor option. We are requesting comment on this analysis and these options.” 

3

 e.g., At 75 Fed. Reg. 9648 (March 3, 2010) EPA finalized its conclusion that beyond the floor controls of organic 

HAP from reciprocating internal combustion engines were not justified, based on cost effectiveness values in the 

range of $20-33,000/ton, as outlined in the proposal (74 Fed. Reg. 9698 (March 5, 2009)). 
6

The current subpart U definition of back-end would also appear to include 

operations that are already regulated under other subpart U provisions. Those 

emissions were fully evaluated in the original rulemaking, the floor was 

established, and control requirements promulgated. Thus, such emissions are not 

“Significant Emission Points Not Previously Regulated” and thus cannot be the 

subject of a new § 112(d)(2) standard. The primary types of such emissions from 

Butyl Rubber source category units are from surge control vessels, a type of 

equipment leak emission regulated by § 63.502 of subpart U, equipment leaks 

from some piping components, also regulated under § 63.502, storage vessels 

regulated by § 63.484 of subpart U, and wastewater, regulated under § 63.501 of 

subpart U. While these emission sources were reported in the ICR submissions, 

they were, rightfully, not included in EPA’s back-end emissions calculations and 

the subpart U definition needs to be made consistent with the development of the 

back-end emission limits. 

For the above reasons, we suggest the definition of back-end in § 63.481 (or at 

least as it applies to the Butyl subcategories) be revised as follows: 

Back-end refers to the unit operations in an EPPU following the stripping 

operations. Back-end process operations include, but are not limited to, 

filtering, coagulation, blending, concentration, drying, separating, and other 

finishing operations, as well as latex and crumb storage. Back-end does not 

include storage and loading of finished product or emission points that are 

regulated under §§ 63.484, 63.501 or 63.502 of this subpart.

B. EPA should revise proposed § 63.483(q)(1) to remove the requirement for 

halogen control for Group 2 continuous front-end process vents. 

Proposed § 63.483(q)(1) includes Group 2 halogenated continuous front end 

process vents from Butyl, Halobutyl and EPR sources in the halogen control 

requirements along with Group 1 vents. No discussion supporting this 

unprecedented requirement is provided in the proposal preamble or in the 

supporting documents, nor are Group 2 vents proposed to be made subject to the 

organic HAP control requirements. This proposal is illogical and, since it lacks 

supporting documentation or explanation, unlawful and should not be finalized. 

For front-end process vents, subpart U follows the typical procedure used in 

process industry rules of identifying each process vent as either Group 1 or Group 

2 on the basis of the vent’s properties. The criteria used for distinguishing between 

Group 1 and Group 2 are the criteria established as the MACT floor or beyond-thefloor level that the supporting analysis demonstrated requires control. That is, 

Group 1 process vents meet the § 112(d) requirements for control and Group 2 

vents do not. In the case of subpart U, the definitions of Group 1 and 2 front-end 

continuous process vents reflect this conclusion from the original rulemaking 

MACT analysis, which EPA has not proposed to change. Nor has the Agency 

proposed requiring control of the organic HAPs in these Group 2 streams, a critical 

step, since the halogen removal requirements are associated with process vents 

that are combusted to comply with an organic HAP removal requirement. 
7

As explained in the preamble to this proposal, the Agency is proposing requiring 

halogen control of Group 1 halogenated front-end continuous process vents where 

a facility opts to meet the existing 98% organic HAP control requirement by 

combustion. The logic for this proposal as presented in the preamble is that 1) the 

halogen emissions are “significant emissions not previously regulated,” 2) such 

control is required under other rules, and 3) this proposed requirement is costeffective as a beyond-the-floor step. Requiring halogen control of Group 2 

halogenated continuous front-end process vents is not mentioned in the preamble 

discussions and meets none of these three criteria. In fact, such a requirement 

would discourage sources from voluntarily reducing organic HAP in these Group 2 

vents and would cause sources to reroute Group 2 halogenated continuous frontend process vents currently routed to the flare to the atmosphere. The original 

MACT analyses found that the vents meeting the Group 2 criteria are not 

significant, since the top 12% of sources were not controlling vents with Group 2 

characteristics. No rule of which we are aware requires halogen or organic HAP 

control for Group 2 process vents since the purpose of the Group 2 designation is 

to distinguish those vents that do not require control. EPA’s own analysis for 

Group 1 continuous front-end process vents indicates control of these vents is only 

marginally cost-effective and thus it certainly would not be cost effective to control 

Group 2 vents. 

The Agency has provided nothing in the record to support this proposed regulatory 

language. There is no preamble discussion and no analyses that would overturn 

the original MACT floor determination. Thus, requirements of the Clean Air Act 

(CAA) and Administrative Procedures Act (APA) have not been met relative to 

requiring control of halogens generated by the combustion of Group 2 halogenated 

continuous front-end process vents. 

Finally, we point out that proposed § 63.485(q) indicates that paragraph (q)(1) 

contains exemptions to the requirements of (q), but the proposed new language for 

(q)(1), in fact, adds the halogen control requirement instead. Thus, the proposed 

language of (q)(1) and the existing language of (q) are inconsistent. As we discuss 

separately, we do not believe requiring halogen control of Group 1 halogenated 

continuous front-end process vent is justified as a beyond-the-floor step, but if the 

Agency decides to finalize that requirement it should revise proposed §§ 63.483(q) 

and (q)(1) as follows to eliminate the Group 2 requirement and to clarify the 

confusing language of the proposal: 

1. If the Agency decides not to finalize the proposed halogen control 

requirements for any of the three subcategories, as we recommend, it should 

leave the existing § 63.485(q) language unchanged. 

2. If the Agency decides to require control of only Group 1 halogenated 

continuous front-end process vents from all three subcategories it should 

simply reserve § 63.485(q)(1). 

3. If the Agency decides to require halogen control of some of the subcategories, 

but not all, it should maintain the existing §§ 63.485(q) and (q)(1) language 
8

and delete the name of the subcategory for which it is adding the halogen 

control requirement from the existing §63.485(q)(1). 

C. The proposed emission limit, and compliance demonstrations, should be 

based on the mass of material going to the back-end. 

Proposed. § 63.494(a)(4) would establish back-end HAP emission limits for the 

Butyl and Halobutyl subcategories, among others. These limits are proposed to be 

expressed in units of Mg organic HAP emissions per Mg of Butyl or Halobutyl 

rubber produced. However, the “mass of rubber produced” is an ambiguous term 

as these units produce more than one product. We recommend the divisor of this 

term be clarified by using more precise terminology. The “mass of rubber 

produced” can be the mass of rubber produced in the polymerization reactor 

(reactor product), the mass of rubber leaving the strippers, or the mass of rubber 

that is shipped to customers or storage (final product or “boxed” production). The 

mass of the latter is somewhat different than the mass of the former two, since 

some off-specification product is discarded as waste, some small amount of 

reactor product is lost through coating out on equipment or being removed when 

equipment is cleared for maintenance, and some finished rubber is reprocessed. 

The definition of back-end in § 63.481 of subpart U is clear on where the back-end 

starts. 

Back-end refers to the unit operations in an EPPU following the stripping 

operations. Back-end process operations include, but are not limited to, 

filtering, coagulation, blending, concentration, drying, separating, and other 

finishing operations, as well as latex and crumb storage. 

With clarity on where the back-end starts, we recommend that the divisor for the 

back-end limit be clearly defined as the “mass of rubber leaving the stripper 

(stripper product).” This is also consistent with the way production is reported in 

the ICR data that served as the basis for this proposal and the CBI letter.

IV. Basis for Establishing the Floor and the Proposed Emission Limitations 

A. EPA does not have legal authority in this rulemaking to establish new limits 

for process vents. 

1. EPA is without authority to impose new standards under §§ 112(d)(2) and 

(d)(3) for the P&R1 source categories since a MACT standard already has 

been promulgated – § 112(d)(6) provides the Agency’s only authority to 

adjust existing MACT standards. 

Once EPA establishes a MACT standard for a particular source category, the 

Agency has the authority under § 112(d)(6) to “review and revise as necessary 

(taking into account developments in practices, processes, and control 

technologies), emissions standards promulgated under this section no less 

often than every 8 years.” In other words, EPA does not have unfettered 
9

discretion to revisit a prior MACT determination once that determination has 

been issued. Rather, EPA may revise a prior determination only “as 

necessary” according to explicit statutory criteria. Cf. New Jersey v. EPA, 517 

F.3d 574, 582 (D.C. Cir. 2008) (“Thus, EPA can point to no persuasive 

evidence suggesting that section 112(c)(9)’s plain text is ambiguous. It is 

therefore bound by section 112(c)(9) because ‘for EPA to avoid a literal 

interpretation at Chevron step one, it must show either that, as a matter of

historical fact, Congress did not mean what it appears to have said, or that, as 

a matter of logic and statutory structure, it almost surely could not have meant 

it,’ Engine Mfrs. Ass’n v. EPA, 88 F.3d 1075, 1089 (D.C. Cir. 1996), showings 

EPA has failed to make.”). 

In this proposal, EPA explains that, “For eight source categories subject to 

three of the MACT standards, we identified significant emission sources within 

the categories for which standards were not previously developed” and that, 

“We are proposing MACT standards for these emission sources pursuant to 

CAA section 112(d)(2) and (3)." 75 Fed. Reg. at 65074. This explanation 

makes it clear that EPA is not invoking § 112(d)(6) as the authority for the new 

proposed standards – indeed, the preamble provides no analysis of 

“developments in practices, processes, and control technologies” to justify the 

proposed standards, as would be required if EPA were relying on § 112(d)(6). 

And, there is no mention of § 112(d)(6) in relation to the proposed new 

standards. Instead, the Agency is invoking §§ 112(d)(2) and (d)(3) directly, as 

if a MACT standard for these sources categories does not already exist. 

As explained above, once EPA makes a MACT determination for a particular 

category, § 112(d)(6) provides the only authority for the Agency to later review 

and possibly revise the determination. Section 112(d)(6) expressly authorizes 

EPA to review existing determinations and provides specific criteria to guide 

and constrain the review. The existence of this express authority forecloses the 

Agency’s ability to directly invoke §§ 112(d)(2) and (d)(3) for a given source 

category when a MACT determination has already been issued for the source 

category. 

Notably, even if the Agency had invoked § 112(d)(6) as authority for revising 

the existing P&R1 rule, it still would not have authority to regulate emissions 

points for which standards were not established in the original rulemaking. The 

original MACT determinations may be revised only “as necessary (taking into 

account developments in practices, processes, and control technologies)....” 

Perceived “gaps” in the original MACT determinations are not “practices, 

processes, and control technologies” that are properly within the scope of a § 

112(d)(6) review. 

2. In any event, it is not a reasonable exercise of authority to establish new 

emissions limitations under an existing NESHAP standard when there is 

no significant risk associated with emissions from sources in the given 

source category. 
10

EPA asserts in the proposed rule the proposition that standards must be 

established for “significant emissions points” not currently regulated under 

existing NESHAP standards – even in circumstances where the Agency has 

determined that the existing NESHAP standard protects health and the 

environment with an ample margin of safety. Establishing new standards under 

these circumstances is patently unreasonable and cannot be justified under § 

112(d)(6). 

In the case of the P&R1 NESHAP, EPA explains that for the Epichlorohydrin 

source category and based on a detailed assessment of risk to health and the 

environment due to HAP emissions from these source categories, “we continue 

to propose that the current MACT standard provides an ample margin of safety 

to protect public health and the environment, and we are proposing to re-adopt 

the existing MACT standard to satisfy section 112(f) of the CAA.” 75 Fed. Reg. 

at 65098. EPA previously had made this determination for both the Butyl 

Rubber and EPR source categories and yet in this rulemaking the Agency 

proposes new emission limitations/controls for Butyl Rubber and EPR front-end 

process vents and Butyl Rubber back-end process vents. 73 Fed. Reg. 76620 

(Dec. 16, 2008). 

As explained above, EPA has no direct authority under §§ 112(d)(2) and (d)(3) 

to create new limits in source categories for which a MACT standard already 

has been promulgated. But, even if EPA had invoked § 112(d)(6) as authority 

for adopting the proposed new standard for back-end process operations, such 

a standard would not be justified because EPA’s own analysis demonstrates 

that the existing MACT standard provides an ample margin of safety to health 

and the environment. In fact, EPA plainly admits for the Epichlorohydrin source 

category that “the MACT standard, prior to the implementation of the proposed 

emission limitation to the back-end process operations discussed in this 

section, provides an ample margin of safety to protect public health.” 75 Fed. 

Reg. at 65099. 

In the case of the Butyl Rubber and EPR source categories, EPA’s residual risk 

evaluation, 73 Fed. Reg. 76220, not only found that the public is protected with 

an ample margin of safety, but that the risks are so low that they would not 

meet EPA’s criteria for population risk reduction (i.e., reducing the number of 

people exposed to an above one in one million cancer risk). In fact, as EPA 

states in the residual risk no further action notice, for these source categories 

“No HAP that are known, probable, or possible human carcinogens are emitted 

from sources in the category.” Id. at 76225, Table 4, Note 6. A similar finding 

is reported relative to EPA hazard index of concern (HI 1.0). EPA concluded 

the maximum hazard index for the EPR source category is 0.5 (due to nhexane) and 0.2 for the butyl source category (due to methyl chloride). Id. at 

76225, Table 4. 

In these circumstances, it is patently unreasonable for EPA to regulate beyond 

the point that the standard has been found to already provide an ample margin 

of safety. This is regulation for the sake of regulation and, as such, contradicts 
11

Congress’s clear intent that an ample margin of safety is an appropriate 

stopping point for emissions limitations under § 112

.4 

B. Back-end Butyl and Halobutyl emissions potentially available for additional 

control. 

The following tables identify the n-hexane emissions that comprise the current floor 

for the back-end and the n-hexane emissions that are potentially available for 

control from the ExxonMobil Baytown Butyl Rubber and Baton Rouge Halobutyl 

Rubber units, based on the information provided to EPA in response to the ICR. 

 

4

 EPA also explains in the context of the proposed new limit for back-end process operations that, because the 

existing MACT standard already provides an ample margin of safety, “we do not believe it will be necessary to 

conduct another residual risk review under CAA section 112(f) for this source category 8 years following promulgation 

of new front-end process vent and back-end process limitations, merely due to the addition of these new MACT 

requirements.” 75 Fed. Reg. at 65111. Implicit in this statement is the suggestion that a residual risk review under § 

112(f) may be needed for new emissions limits that are established for existing MACT standards. As with setting 

MACT standards in the first instance, § 112(f) provides a one-time opportunity for conducting a residual risk review of 

a MACT standard. There is no basis under the law for the suggestion that a revision to an existing MACT standard 

triggers the need for another § 112(f) residual risk review. Indeed, the proposal provides no explanation whatsoever 

as to why such a subsequent review could be required under the law. 
12

Baytown Butyl Rubber Unit (Butyl Subcategory) 

2009 Back-end Emissions, n-hexane 

Emission ID/Description 

Emissions 

Tons/Year Comments 

 

RGTO 28.09 Partially controlled; reported 

to EPA in ICR; includes 

maintenance bypasses of 

existing RTO 

BPBFinish 26.19 Uncontrolled; reported to EPA 

in ICR 

 

Subtotal 54.28 

Less equipment leaks (including 

surge control vessel emissions) in 

BPBFinish and RGTO 

11.27 Emission limit should be 

based on emissions not 

already subject to subpart U 

requirements 

Basis for floor 43.01 Prior to including variability 

Less emissions already controlled 17.24 Emissions from existing RTO 

Emissions basis for beyond-thefloor analysis (Note 1)  25.77 

 

 Note 1: This item includes emissions not routed to the RTO and emissions 

associated with maintaining the existing RTO, as discussed in item E of this 

section and in our discussion of the beyond-the-floor analysis in Section V. 
13

Baton Rouge Butyl Rubber Unit (Halobutyl Subcategory) 

2006 Back-end Emissions, n-hexane 

Emission ID/Description 

Emissions, 

Tons/Year Comments 

S-88, TTU 18.32 Controlled: reported to EPA in ICR 

M-53, M-58, V-127, V-131 41.66 Uncontrolled; reported to EPA in ICR; 

continuous process vents and 

maintenance bypasses of existing 

RTO 

Basis for floor 59.98 Prior to including variability 

Less emissions already 

controlled 

18.32 Emissions from existing RTO 

Emissions basis for beyondthe-floor analysis (Note 1) 

41.66 

Note 1: This item includes emissions not routed to the RTO and emissions 

associated with maintaining the existing RTO, as discussed in item E of this 

section and in our discussion of the beyond-the-floor analysis in Section V. 

C. EPA must include variability in establishing back-end emission limitations 

for the floor or for the proposed new requirements.

In establishing the back-end emission limits for the Butyl and Halobutyl 

subcategories. EPA did not consider variability, which is appropriate in setting 

emission standards. It is acceptable and expected for EPA to consider emission 

levels associated with normally anticipated and recurring operating conditions, 

and decisions of the D.C. Circuit acknowledge that data from more adverse 

operating conditions can inform the basis of the standard. Thus, EPA should 

establish a standard that MACT floor units can meet if operating “under the most 

adverse circumstances which can reasonably be expected to recur.” Sierra Club 

v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999), quoting National Lime Ass’n v. EPA, 

627 F.2d 416, 431 n.46 (D.C. Cir. 1980). 

Indeed, in that 1999 Sierra Club decision, the court emphasized: 

"EPA would be justified in setting the floors at a level that is a reasonable 

estimate of the performance of the ‘best controlled similar unit’ under the worst 

reasonably foreseeable circumstances ...." 

167 F.3d at 665. Accord Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855, 

863 (D.C. Cir. 2001). 
14

 In the Cement Kiln case, EPA argued that it is acceptable for it to consider the 

range of emissions from the best performing sources and that test results at more 

adverse conditions “’are more helpful than normal operating data would be in 

estimating performance under a variety of conditions and thus in helping to assure 

that properly designed and operated sources can achieve the standard.’” Cement 

Kiln, 255 F.3d at 867 (quoting EPA). The court affirmed this interpretation. Id. 

Furthermore, the D.C. Circuit in its 2004 decision in Mossville Environmental 

Action Now v. EPA "held that floors may legitimately account for variability 

because "'each [source] must meet the [specified] standard every day and under 

all operating conditions.'” 370 F.3d 1232, 1242 (D.C. Cir. 2004), as quoted in 

Sierra Club v. EPA, 479 F.3d 875, 882 (D.C. Cir. 2007). 

 In this proposal, EPA only used one data point, the emissions level for one year 

for the units in the Butyl Rubber source category, and did not look at statistical 

variation over time. And if EPA revisits the Butyl Rubber subcategories then EPA 

should also consider other factors such as the variability in source design and 

operation within a subcategory.

 D. The emission limitation for the back-end process in the Butyl Rubber 

subcategories should reflect several variability factors that impact 

emissions. 

For the Butyl Rubber subcategories, there are a number of factors that contribute 

to the variability of organic HAP emissions on an emissions per unit of production 

basis. These factors include production itself, as not all emissions (e.g., surge 

control vessels) are a function of production. Other factors include grade slate 

changes, operating and weather conditions, process reliability and control device 

reliability/service factor. As an example, several pieces of equipment (primarily 

the flash drums and strippers) are used to remove hexane from the polymer 

slurry fed to the back-end. Through normal process variations in temperature, 

pressure, liquid level, and fouling rates in the flash drum/stripper equipment, the 

amount of hexane fed to the back-end can vary. Also, the current RTOs require 

maintenance on a variable frequency, oftentimes several multi-day instances per 

year. This is impacted by equipment age and service life. 

In determining annual emissions variability our focus was on the Baton Rouge 

Halobutyl unit. The significant investments and modifications at the Baytown unit 

over the last ten years results in a more difficult analysis to differentiate variability 

from the impact of process changes. The table included in the CBI letter 

summarizes annual emissions per unit of production at the Baton Rouge facility 

for the last ten years. 

As detailed in our CBI letter, over the last ten years the n-hexane back-end 

emissions per unit of production varied by 43% from 2006 at Baton Rouge, with 

2006, the year reported in the ICR, among the lowest years in the time period. In 

order to appropriately capture the variability in emissions, with 2006 as the base 

year, the floor emission limit or the post new control emission limit should be 
15

increased by at least 43%. Using only the 2006 data would mean that the site 

could not have met the limit in four of the last five years, which clearly would not 

represent the current floor or future capability under the existing subpart U. 

A variability adjustment of at least 43% is also a reasonable adjustment for the 

ExxonMobil Baytown Butyl Unit, because the factors it represents (i.e., proportion 

of emissions that vary with production, grade slate changes, operating 

conditions, process reliability and control device reliability/service factor) are 

similar to those for the ExxonMobil Baton Rouge Halobutyl Unit. 

E. EPA must recognize that maintenance of the existing regenerative thermal 

oxidizers (RTOs) is required to achieve maximum organic HAP destruction. 

As also discussed in section VI, RTOs are the preferred control devices for 

controlling back-end emissions because of their energy efficiency (and thus 

much lower energy consumption and secondary emissions) when combusting 

large streams of air containing only low concentrations of hydrocarbon. 

However, in exchange for their efficiency in handling dilute air streams with a 

reasonable energy demand, RTOs require regular maintenance. RTOs operate 

by having two packed bed reactors, one that is hot and handling the hydrocarbon 

destruction and one that is being heated up by the exhaust gas from the first bed. 

These beds switch regularly as the bed temperature of the in-service reactor 

drops to a preset point. Large, automated valves make the bed switches quickly 

and efficiently. However, this is a difficult service and valve leakage is a 

predictable problem. Such leakage allows some hydrocarbon to bypass the hot 

reactor and the desired overall 98% organic HAP removal could quickly be 

unachievable. Thus, it is critical that these valves be well-maintained, which also 

is required by the general duty requirement in proposed § 63.483(a)(1) to 

maintain control equipment. In order to do this maintenance, the RTO must 

sometimes be bypassed while the back-end continues to operate. In addition to 

valve maintenance, these systems have other moving parts and packed beds in 

demanding services that sometimes must be maintained with the RTO out-ofservice. For instance, corrosion is an ongoing problem in the collection system 

and repair of that system sometimes requires an RTO outage. The timing of 

RTO maintenance cannot always be set with back-end outages. 

It appears that EPA’s proposed emission limit did not account for the need to 

bypass the back-end control devices to allow this maintenance, though these 

emissions are reported in our ICR submissions. The existing Butyl back-end 

sources at Baytown are currently permitted to allow bypass emissions during 

maintenance work on the control device up to the permitted limit, and with the 

use of purchased Emission Reduction Credits, the bypass is allowed under the 

State 30 TAC 115 VOC rules. At Baton Rouge an allowance for bypass 

emissions is included in the unit operating permit. 

This issue can be addressed by establishing a back-end emission limit that 

recognizes the bypassing that currently occurs for the current RTO-controlled 

emissions and by allowing for it for any additional emissions that will be 
16

controlled by an RTO. We have indicated this in our tables of emissions in 

Section V. 

F. Summary of Butyl Rubber back-end floor. 

The following table summarizes the recommended emissions basis for the floor 

level of emissions for the ExxonMobil Baytown Butyl and Baton Rouge Halobutyl 

units: 

Floor Analysis Summary 

 n-hexane, Tons 

 

Baytown Butyl Baton Rouge Halobutyl 

Basis for floor 43.01 59.98 

Variability adjustment 

(43% minimum) 

18.49 25.79 

Floor emission limit 61.50 85.77 

 

Should the Agency impose back-end emission limits, those limits should include at 

least a 43% adjustment for variability and include an equivalent maintenance 

allowance to that demonstrated to be needed for the existing RTOs for any 

additional emissions that will require new control.

V. Basis for Beyond-the-Floor Decisions 

As explained above, EPA has no direct authority under §§ 112(d)(2) and (3) to 

create new limits in source categories for which a MACT standard already has been 

promulgated. Furthermore, as explained below, EPA has no authority or factual 

basis to re-visit the beyond-the-floor analyses conducted in 1996. 

A. EPA already made the decision that beyond the floor controls for 

continuous front-end process vents were not cost-effective in the 1996 

rulemaking. EPA has no authority and no grounds to perform a second § 

112(d)(2) analysis for these emission points. 

In the 1996 final rule, EPA was aware that halogenated vent streams were vented 

to a flare or boiler at Butyl Rubber, Halobutyl Rubber, and EPR facilities. While 

the flare or boiler provided control for the organic HAP, methyl chloride, it was 

well-known that hydrogen chloride would be generated by the combustion 

process. After considering this information, EPA determined that the floor for 

control of this organic HAP was combustion in a flare or boiler and that beyondthe-floor control of the HCl generated in the combustion was not cost-effective and 

not justified. EPA explained: 
17

Only one existing facility was identified in each of the Halobutyl and the Butyl 

rubber subcategories. At both of these facilities, halogenated vent streams 

were vented to a flare and/or boiler. Since both of these subcategories were 

single-facility subcategories, the MACT floor was determined to be the 

existing level of control. The EPA examined the impacts of requiring 

halogenated vent streams at the Halobutyl and Butyl rubber facilities to 

comply with the proposed requirements for all other elastomer subcategories 

(i.e., the HON-level of control). The EPA concluded that the costs associated 

with this level of control were not reasonable, given the associated emission 

reduction. Therefore, the proposed regulation allowed halogenated streams at 

Halobutyl and Butyl rubber facilities that were routed to a flare or boiler prior 

to proposal to continue to be controlled with these combustion devices, 

without additional control for the resulting halides. ...

...[T]he EPA concluded that four of the five EPR facilities have halogenated 

streams that are routed to either a boiler or flare. For this reason, the EPA 

has determined that the floor for EPR is the existing level of control for these 

halogenated vent streams. In addition, as with Halobutyl and Butyl rubber, the 

EPA does not believe that it would be cost-effective to require new 

incinerators and scrubbers to be installed at these facilities, when the only net 

emission reduction would be the reduction of the hydrochloric acid, since the 

reduction of the halogenated organic compound in the incinerator would be 

the same as was already being achieved in the boiler or flare. However, as 

noted above, sufficient stream-specific information was not available to 

conduct this analysis. Therefore, the final rule has been changed to extend 

the exemption for existing halogenated streams routed to a boiler or flare to 

EPR producers. Further, the final rule specifies that this exemption does not 

apply to new sources. 

61 Fed. Reg. at 46919. 

This passage from the 1996 rulemaking clearly demonstrates that EPA has 

conducted a complete analysis under §§ 112(d)(2) and (d)(3). Therefore, EPA 

met its obligation to set a technology-based emissions standard for these HAPs in 

these categories and subcategories. EPA’s only authority to revisit the 

rulemaking, in the absence of a timely legal challenge to this particular standard in 

the P&R1 rule, which was not lodged, are the 8-year technology review and the 

one-time residual risk review. Those reviews, too, were completed and final 

action noticed at 73 Fed. Reg. 76220, again without challenge. Even as part of a 

periodic technology review, EPA is not required, and we believe not allowed, to 

“start from scratch.” NRDC v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008). 

The 1996 rulemaking also undercuts EPA’s claimed basis for revisiting the 

standard – the “absence of a standard for a significant emissions source.” 75 Fed. 

Reg. at 65108-65109. EPA performed the required standard-setting analysis 

under § 112(d)(2) consistent with D.C. Circuit precedent. This is not a case of “no 

control floors” or source “exemptions,” which the D.C. Circuit has held to be 

unlawful under section 112. Nat’l Lime Ass’n v. EPA, 233 F.3d 625 (D.C. Cir. 

2000); Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008) cert. denied, 130 S. Ct. 
18

1735 (2010). In this case, EPA determined that the existing level of control for the 

halogenated compounds – a flare or boiler – was all that was required, and the 

reduction in HCl was not the floor and not cost-effective. The “exemption” in the 

1996 rule is from “HON-level” controls, not all control. 

We are not aware of any prior MACT rule where EPA, in the absence of a court 

decision, rule vacatur, or settlement agreement, revisited a beyond-the-floor 

analysis. EPA should not do so in this rule. 

B. EPA’s beyond-the-floor determination for halogenated front-end process 

vents at the ExxonMobil Baton Rouge EPR Unit that is based on sharing 

controls with the co-located Halobutyl Unit exceeds EPA’s legal authority 

and is technically and operationally impractical. 

1. EPA does not have the legal authority to justify beyond-the-floor controls 

in one source category by combining the source category with controls 

for another source category. Decisions must be made on a source 

category by source category basis. 

Section 112(d) directs EPA to establish emission standards for each category 

or subcategory of major sources of listed HAPs. In considering whether to 

impose a standard “beyond the MACT floor” on a category or subcategory, EPA 

must consider among other factors “the cost of achieving such emission 

reduction.” § 112(d)(2). To meet this directive, EPA performs a costeffectiveness analysis using the cost of potential beyond-the-floor controls and 

the resulting tons per year emission reduction. 

Although EPA has discretion in considering costs in setting emission standards 

under CAA programs, e.g. Husqvarna AB v. EPA, 254 F.3d 195 (D.C. Cir. 

2001), EPA’s discretion is not unlimited. Arteva Specialties v. EPA, 323 F.3d 

1088 (D.C. Cir. 2003) (remanding LDAR provisions of Group IV Polymers & 

Resins NESHAP to EPA based on fact that record did not support that EPA’s 

cost-effectiveness analysis was reasonable). EPA’s basis and methodology for 

analyzing costs must be reasonable and comport with the underlying statutory 

provisions. Section 112 is structured to impose emissions standards on 

individual source categories, and EPA is required to conduct a separate 

analysis for each category or subcategory. § 112(d)(1). While EPA grouped 

nine source categories, and several subcategories, under subpart U based on 

similarities in emission points and types of controls, EPA originally considered 

each category and subcategory on its own merits, including the cost of 

achieving emission reductions. 61 Fed. Reg. at 46908.

In the current proposed rule, EPA found that one of three EPR existing units 

(the ExxonMobil Baton Rouge EPR Unit) combusted halogenated continuous 

front-end process vents in a flare, resulting in some byproduct HCl emissions. 

75 Fed. Reg. at 65108. EPA similarly determined that the one unit in each of 

the subcategories Butyl Rubber and Halobutyl Rubber combusted halogenated 

continuous front-end process vents in a flare. Id. at 65109. As discussed, this 

was also the case during the 1996 rulemaking and was considered at that time. 
19

Hazardous Air Pollutant Emissions from Process Units in the Elastomer 

Manufacturing Industry, Basis and purpose Document for Proposed Standards, 

EPA 453/R-95-006a, May 1995, section 6. After conducting a new beyond-thefloor analysis, EPA is proposing beyond-the-floor requirements for halogenated 

continuous front-end process vents for all three source categories. Under this 

new set of requirements, these vents could not be sent to a flare and, if 

combustion is used to control the organic HAP, the HCl produced by the 

combustion would have to be removed. The most practical control alternate, 

and the one evaluated in the beyond-the-floor analysis, is installation of a new 

thermal oxidizer followed by a halogen scrubber. Id. at 65108-65110. 

For the Butyl Rubber and Halobutyl Rubber units, EPA’s cost analysis 

concluded that the additional controls would be reasonable and cost-effective. 

However, for the EPR unit, EPA found that the additional control was not costeffective. The Agency then re-evaluated controls for that EPR facility on the 

basis that it would share the additional controls with the Halobutyl Rubber unit, 

with which it is co-located. For this shared control case, EPA concluded that 

the additional controls are cost-effective. Id. at 65109-65110. More 

specifically, in the “Regulatory Alternative Impacts for Group 1 Polymers and 

Resins Source Categories”, dated July 19, 2010, EPA notes that the costeffectiveness for halogenated continuous front-end process vent beyond-thefloor controls on the ExxonMobil Baton Rouge EPR Unit is $21,600/ton, for the 

ExxonMobil Baton Rouge Halobutyl Rubber Unit it is $5,800/ton, and if you 

combine the vents from the two units the cost effectiveness is $6,700/ton. 

EPA is, however, required to perform the beyond-the-floor analysis, including 

cost consideration, separately for each source category or subcategory. EPA 

recognized as much during the original subpart U rulemaking when EPA 

determined that beyond-the-floor controls were not cost-effective for the Butyl 

Rubber and Halobutyl Rubber facilities. 61 Fed. Reg. 66919. Furthermore, in 

litigation over the Group IV P & R rule, 40 CFR Part 63, Subpart JJJ, EPA 

clearly explained that it conducted a separate cost-effectiveness analysis for 

each subcategory. EPA told the court: 

EPA then determined, with one exception, that the rule was achievable 

considering costs, based on cost effectiveness for each subcategory ....

FN5. Within the PET manufacturing category, plants use different 

feedstocks (dimethyl terephthalate (“DMT”) or terephthalic acid (“TPA”)) and 

different processes (batch or continuous), which may affect emission 

characteristics and controllability. 60 Fed. Reg. at 16,092 (March 29, 1995). 

Based on these factors, EPA created five subcategories: DMT-batch, DMTcontinuous, TPA-batch, TPA-continuous and TPA-continuous multiple end 

finisher. Id. Any one facility may have multiple process units that fall under 

different subcategories. In determining whether to adopt beyond-the-floor 

leak detection and repair standards for each subcategory, EPA conducted 

separate analyses for each subcategory.

Brief of Respondent EPA, Arteva Specialties, 323 F.3d 1088 (emphasis added). 
20

Thus, EPA understood and represented to the court that it must conduct a 

separate cost analysis for each subcategory, even when affected units could be 

co-located and potentially share control equipment.

In the instant rulemaking, EPA cannot fabricate cost-effectiveness by assuming 

units in separate source categories could share control devices. Section 112(d) 

requires category-by-category standard-setting, and we are aware of no other 

rulemaking where EPA has combined different source categories for the 

purpose of setting NESHAP standards. Moreover, it is unreasonable, arbitrary 

and capricious for EPA to take advantage of the fact that these source 

categories and subcategories are comprised of a single source (or essentially a 

single source in the case of the EPR analysis where only one facility reported 

HCl emissions). In a typical situation where a source category would consist of 

multiple facilities, EPA would never be able to make a cost-effectiveness 

determination on such a facility-specific basis. 

2. EPA’s analysis, based on combining the Butyl Rubber (Halobutyl 

subcategory) and EPR source categories to justify beyond-the-floor 

halogenated continuous front-end process vent controls for the EPR 

source category, is inappropriate and inconsistent with maintaining 

business operating flexibility and how controls would be implemented. 

While it is common practice to tie numerous operating units/ source categories 

to a flare system for control, this practice becomes problematic for control 

devices that require a higher level of preventive and ongoing maintenance. 

Flare systems are relatively low-maintenance and operate for many years 

without outages. Additionally, multiple flares are usually connected in order to 

provide continued emission control even if a particular flare is being maintained. 

Thermal oxidizers and halogen scrubbers, on the other hand, due to more 

moving parts and the severity of service, require more maintenance and 

typically are not spared (and the cost of sparing was not included in the cost or 

cost-effectiveness analyses). In this particular service, corrosion is expected to 

be a particular service factor issue. Sharing a thermal oxidizer/scrubber 

system, as EPA proposes, puts the operation of both units at unacceptable risk. 

Any significant maintenance need or outage of the control would require the 

shutdown of both units. Unplanned shutdowns of the control would result in 

dual violations (since shutdowns take time) and potentially large shutdown 

excess emissions as both units would have to make simultaneous emergency 

shutdowns. This causes many problems. Supplies of both products would be 

impacted and startup and shutdown costs and emission increases would occur 

unnecessarily. Another concern would be extended maintenance shutdowns of 

the shared control, because advantage could not be taken of the downtime to 

coincide major turnarounds on the two process units. Because of the size and 

complexity of these units, simultaneous major turnarounds are not feasible. 

Overall, then, having a shared control, will cause lost production, extra process 

unit outages and increased emissions. 

The Halobutyl Rubber and EPR businesses at Baton Rouge are distinctly 

different in terms of the customer base, supply chain for alternate sourcing, and 
21

operating flexibility. Since the proposed incinerator/scrubber requirement, in 

EPA’s analysis, ties the two units together, operating flexibility is limited as 

discussed above. Feedback from the businesses indicates that this is an 

unacceptable business basis and that separate control devices are needed to 

assure business viability. Consequently, EPA’s analysis either needs to 

consider significant lost business and other costs and emission impacts in the 

beyond-the-the floor analysis for the proposed combined control; include the 

significant cost of a spare thermal oxidizer and halogen scrubber, which would 

clearly result in a determination that the controls are not cost-effective; or justify 

the new halogen control requirement on the basis of separate controls for each 

unit. 

While we do not provide detailed cost estimates in Section VI for 

incinerator/scrubber controls separately for the Halobutyl Rubber and EPR 

source categories (primarily because we knew even on a combined basis 

controls are not cost-effective), we have scaled the estimate we developed for 

a shared control to two separate units that would handle the flow from the 

separate production units. Using that cost basis, results in the following costeffectiveness result: 

 1. Halobutyl Rubber: > $20,600/ton 

 2. EPR: > $51,000/ton 

For both of these cases, this analysis indicates that controls are not costeffective. 

C. The cost-effectiveness criteria for this proposal was not clearly defined by 

EPA, but recent experience suggests a level of approximately $10,000 per 

ton of HAP reduced. 

In the proposal, EPA does not clearly indicate what the cost-effectiveness criterion 

is for decision-making to require controls in the beyond-the-floor analysis. EPA 

determined that front-end controls for Butyl Rubber ($7,900 per ton of HAP 

reduced), front-end controls for Halobutyl and EPR combined ($6,700), and backend controls for Butyl Rubber ($7,000) were cost-effective. Back-end controls for 

Halobutyl Rubber ($47,300) and front-end controls for EPR alone ($21,600) were 

not considered cost-effective. 

In other rulemakings, factors that appear to be considered when EPA determines 

cost-effectiveness include the toxicity of the HAP (mercury, for example, would 

justify a higher cost-effectiveness criteria) and whether or not there are significant 

co-pollutant reduction benefits. As already determined by EPA’s residual risk 

analysis, the health risk and concerns associated with the HAP emissions from the 

Butyl Rubber and EPR source categories are minimal. Although ExxonMobil 

generally does not agree that EPA has authority to base NESHAP decisions on 

co-pollution reductions, co-pollutant reductions for the proposed front-end controls 

and for the Butyl Rubber subcategory are minimal and don’t factor into the 

analysis. 
22

Several other EPA decisions on cost-effectiveness were reviewed and noted as 

follows: 

1. For Epichlorohydrin Elastomer Production, which is also addressed in this 

proposal, EPA determined that the beyond-the-floor cost of $31,000/ton for 

back-end process operations, to achieve a 35 ton/year HAP reduction, was not 

justified. EPA also noted that since the reduction was due to toluene there 

would be no reduction of cancer risk, a similar situation to the n-hexane 

emissions from the Butyl Rubber source category back-end operations. It was 

also noted that there would be increases in criteria pollutants and an increase 

in energy use. 75 Fed. Reg. 65099. 

2. In another chemical industry rule EPA determined that “... the incremental 

cost-effectiveness relative to the 85 percent control option is estimated to be 

$13,500/ton. This cost is unreasonable.” NESHAP for Chemical 

Manufacturing Area Sources; October 29, 2009; 74 Fed. Reg. 56023. 

3. In the Miscellaneous Organic NESHAP (MON), another chemical industry 

rulemaking, EPA determined that various beyond-the-floor options in the 

$13,300 to $17,300 range were not cost-effective. The options related to 

lowering the control trigger level for batch process vents, lowering the control 

trigger for flow and concentration for wastewater, and lowering the HAP vapor 

pressure trigger for storage vessels. Hazardous Air Pollutant Emissions from 

Miscellaneous Organic Chemical Manufacturing and Miscellaneous Coating 

Manufacturing, able 5.1, p 5-8, September 2001. 

 

In summary, while EPA did not clearly define the cost-effectiveness criteria for this 

rulemaking, it appears that using no more than $10,000/ton would be consistent 

with other Agency decisions for a rule of this type and for the HAP emissions 

targeted. Any substantive increase in this metric for this rulemaking would be 

arbitrary as there appears to be no basis for a substantive change in policy. 
23

D. Summary of the emission sources to be included in evaluating the beyondthe-floor options. 

If, despite its lack of authority, EPA proceeds to finalize further controls, the tables 

that follow summarize, for halogenated continuous front-end process vents, the 

appropriate HCI emissions basis for a beyond-the-floor analysis for the Butyl and 

EPR facilities and the potential maximum HCI reductions. The back-end beyondthe-floor emissions basis analysis was included in Section IV of these comments. 

1. Baytown Butyl Rubber Front-End 

2009 Emissions, HCl 

Emission ID/Description 

Emissions 

tons/year Comments 

FS12 (flare stack) 30.09 Reported to EPA in ICR 

Less emissions not from 

continuous process vents 

 5.39 Loading rack, exchanger 

depressurization, safety bypass 

Basis for beyond-the-floor 

analysis 

24.70 

Potential emissions 

reduction with controls 

 24.5 99% control 

 

2. Baton Rouge Halobutyl Rubber Front-End 

2006 Emissions, HCl 

Emission ID/Description 

Emissions 

tons/year Comments 

Emissions reported to EPA 76.80 Reported to EPA in ICR 

Basis for beyond-the-floor 

analysis 

76.80 

Potential emission reduction 

with controls 

76.0 99% control 
24

3. Baton Rouge EPR Front-End 

2005 Emissions, HCl 

Emission ID/Description 

Emissions 

tons/year Comments 

Emissions reported to EPA 24.05 Reported to EPA in ICR 

Basis for beyond-the-floor 

analysis 

24.05 

Emissions reduction with 

controls 

23.8 99% control 

E. The proposed front-end beyond-the-floor controls for Baton Rouge 

Halobutyl, Baton Rouge EPR, and Baytown Butyl Rubber are not costeffective and should not be finalized. 

In the proposed rule EPA determined that halogen controls on the halogenated 

continuous front-end process vents for the EPR source category and the Butyl and 

Halobuyl subcategories of the Butyl Rubber source category, based on installation 

of an incinerator and scrubber, are justified based on cost-effectiveness. The 

ExxonMobil cost analysis, which is included in Section VI of these comments and 

is based on a significant engineering scoping and cost estimating effort, indicates 

that the controls are not justified. 

In addition to cost, the cost-effectiveness calculation requires an estimate of the 

emission reduction that will be achieved. For Group 1 halogenated front-end 

process vents, the potential emission reduction can be estimated as 99% (the 

required HCl removal) times the amount of HCl generated from combusting the 

chlorinated organic HAPs in the vents. In subsection D, above, we provided our 

estimate of the HCl emission reduction potential, which is slightly different from the 

EPA estimates due to clarifications of the data provided to EPA in our ICR 

response. 

The cost-effectiveness for the proposed halogenated continuous front-end 

process vent requirements ranges from $20,000/ton to $80,000/ton. The EPA and 

ExxonMobil analyses are summarized below. 
25

Cost-Effectiveness for Proposed Front-end HCI Control 

EPA Analysis 

Process 

Capital 

Cost 

$K 

Annual 

Cost 

$K 

HCl 

Reductions 

Tons/Year 

Costeffectiveness 

$/Ton 

Baton 

Rouge 

EPR 

985 424 19.6 21,600 

Baton 

Rouge 

Halobutyl 

985 445 76.0 5,900 

Baton 

Rouge 

Combined 

 1,120 642 95.6 6,700 

Baytown 

Butyl 

669 235 29.8 7,900 

ExxonMobil Analysis 

Process 

Capital 

Cost 

$K1

Annual 

Cost 

$K 

HCl 

Reductions 

Tons/Year 

Costeffectiveness 

$/Ton Comments

Baton Rouge 

EPR 

9,600 1,220 23.8 51,100 

Baton Rouge 

Halobutyl 

12,400 1,570 76.0 20,700 

Baton Rouge 

Combined 

13,300 1,690 99.8 16,900 Not 

practical/ 

legal case 

Baytown 

Butyl 

16,200 1,960 24.5 80,100 

1

 Includes Project Services costs 

Note: Annual cost includes capital cost times a capital recovery factor of .1098 

(as proposed) plus operating costs. 

F. The proposed back-end beyond-the-floor controls for Baton Rouge 

Halobutyl and Baytown Butyl Rubber are not cost-effective and should not 

be finalized. 
26

In the proposal beyond-the-floor analysis, EPA determined that additional controls 

on the back-end vents for the Baytown Butyl Rubber unit were justified based on 

cost-effectiveness, and that additional controls for the Baton Rouge Halobutyl 

Rubber unit were not cost-justified. The ExxonMobil analysis, on the other hand 

shows that control of the back-end process is not cost-effective for either unit. 

The cost-effectiveness for the proposed back-end control requirements ranges 

from $55,000/ton to $70,000/ton. 

Section VI provides our estimates of the cost for the controls that would be 

required to comply with the proposal, based on a significant engineering scoping 

and cost estimating effort. For the reasons discussed in Section VI, these cost 

estimates are the best available cost basis for use in the beyond-the-floor 

calculations for the proposed Butyl and Halobutyl controls and EPA should adopt 

them. 

In addition to cost, the cost-effectiveness calculation requires an estimate of the 

emission reduction that will be achieved. For the back-end processes, the 

potential emission reductions are lower than EPA has estimated. Our estimate of 

the emission reduction potential is as follows, beginning with our estimate of the 

emissions basis for the beyond-the-floor analysis, as derived in Section IV of 

these comments. 

Potential Emission Reductions 

(Tons organic HAP) 

 

Baytown 

Butyl 

Baton Rouge 

Halobutyl Comments 

Emissions basis for the 

beyond-the-floor analysis 

from Section IV.B 

25.77 41.66 

Less maintenance 

bypasses around existing 

RTOs 

20.77 34.91 Required to maintain 98% 

destruction during normal 

operation of the existing 

RTOs (See discussion in 

Section IV) 

Emissions after allowance 

for capture inefficiency 

(1%) 

20.56 34.56 

Emissions after allowance 

for RTO destruction 

inefficiency (2%) 

20.15 33.87 

Note: For base years reported in ICR 
27

The cost effectiveness for the proposed back-end process emission limitations 

are summarized as follows. 

Cost Effectiveness for Proposed Back-end Control 

EPA Analysis 

Process 

Capital 

Cost 

$K 

Annual 

Cost 

$K 

n-hexane 

Reductions 

Tons/Year 

Costeffectiveness 

$/Ton 

Baton 

Rouge 

Halobutyl 

951 1,607 34.0 47,300 

Baytown 

Butyl 

235 181 25.7 7,000 

ExxonMobil Analysis 

Process 

Capital 

Cost 

$K1

Annual 

Cost 

$K 

n-hexane 

Reductions 

Tons/Year 

Costeffectiveness 

$/Ton 

Baton 

Rouge 

Halobutyl 

18,100 2,450 33.9 72,300 

Baytown 

Butyl 

12,500 1,530 20.2 75,600 

 1 Includes Project Services costs 

G. EPA should update the Economic Impact Analysis to reflect more realistic 

industry costs and the reduced U.S. competitiveness that will result from 

the proposed added control costs. 

EPA included in the docket the “Economic Impact Analysis for National Emission 

Standards for Hazardous Air Pollutant Emissions: Group I Polymers and Resins”, 

dated July 16, 2010. In the memo EPA summarized the annualized costs for the 

P&R1 facilities and provided an estimate of the cost to sales ratio. EPA needs to 

update the Economic Impact Analysis for the following reasons: 

1. As indicated in this comment package, EPA has significantly underestimated 

the cost of controls. 

2. The analysis lacks any assessment of the impact on U.S. supply 

competitiveness as a result of increased U.S. manufacturing costs not incurred 

by other worldwide suppliers. In international markets added costs incurred by 
28

one geographic region are unlikely to be passed along to customers, thereby 

reducing incentives to supply from the U.S. 

3. The analysis lacks any assessment of the impact of the proposed shared 

Halobutyl/EPR control on operating flexibility, supply capability, or international 

competitiveness of the two businesses. 

 

VI. Emission Control Cost 

A. ExxonMobil has extensive experience and comprehensive systems for the 

development and execution of capital projects. 

 For more than 125 years, ExxonMobil has been a leader in the evolution of 

energy and energy technology. Worldwide capital and exploration expenditures 

have averaged over $20 billion for the last five years. A key to the company’s 

success has been a disciplined capital management plan coupled with the goal 

of flawless project implementation. 

 ExxonMobil’s proven project management system incorporates best practices 

developed around the world. Emphasis on the early phases of concept selection 

and effective project execution results in investments that maximize resource and 

asset value. We also complete a rigorous reappraisal of all major projects and 

incorporate the findings from these reappraisals into future project planning and 

design, further strengthening our capabilities.

B. ExxonMobil has a structured process to develop capital projects, including 

cost estimates. 

 ExxonMobil has a capital project management system that uses periodic 

management gate reviews and check points to ensure that capital investments 

are aligned with safety, environmental, and business needs. The structured 

activities included in the process are designed to assure that projects are 

conducted in a safe and environmentally responsible manner, deliver assets of 

appropriate quality, meet cost and schedule expectations, and achieve 

commercial success. The system provides a common framework for capital 

projects across the entire company. 

 The various project stages include: development planning; evaluation/selection of 

alternatives; further optimization/definition; detailed design, procurement, 

construction; and startup/operation. A project proceeds through a series of gates 

with each gate representing a milestone decision point based on an acceptable 

level of project definition. The gates typically represent go/no-go decision points 

for business ventures; for other projects (e.g. safety/environmental) they 

represent detailed reviews of project bases, critical path activities, and project 

schedule/success risks. A gate review would include various project elements, 

including, for example, technology selection, funding, staffing, planning issues, 

project cost estimates, contracting/purchasing strategies, safety and 

environmental considerations, information management, and project timeline. 
29

C. ExxonMobil prepared cost estimates for the proposed controls as the first 

step in project development. 

 During typical project development ExxonMobil prepares a number of estimates 

with each reflecting cost of the project at some defined milestone of design 

definition. As project definition is improved throughout the development process 

project estimating accuracy improves. 

 Typical project estimates include: 

1. Direct material: identified material costs for the physical components of 

permanent plant facilities; equipment (e.g. emission control devices, heat 

exchangers, pumps, distillation columns); other material items (e.g. piping, 

instrumentation, electrical, structural steel, concrete pads). 

2. Direct labor: field installation costs, including prime contractor and 

subcontractors. 

3. Indirect costs: overhead costs associated with plant construction (e.g. 

scaffolding, field supervision, construction equipment); costs for engineering 

and procurement of permanent plant facilities. 

4. Contingency: budget for future changes that are expected but are unknown at 

the time of the estimate (e.g. design changes, execution developments). 

 In developing cost estimates for the controls required to comply with this 

proposal, ExxonMobil included the following steps: 

1. Cost estimators worked closely with site technical contacts to develop a 

project basis. This information includes: 

(i) Location of each emission source and the routing of the piping/ducting to 

the oxidizer. 

(ii) Stream characteristics, such as gas flow and concentration. 

(iii) Oxidizer location and location of utilities.

(iv) Other items that will be required to install the oxidizers (e.g. demolition of 

old facilities to make room for the new equipment, structural modifications 

needed to install the back-end controls on a finishing (back-end) building’s 

roof). 

2. The cost estimators visited the sites to survey the existing plants and the 

proposed locations of the new equipment. The purpose of this visit was for 

the cost estimator to understand the project scope and to try to identify any 

complexities and complications that would affect the cost estimate. 

(i) The team reviewed potential issues with supporting systems (e.g. 

wastewater treatment facilities, availability of electrical connections, other 

utilities). 
30

(ii) The team reviewed site access and congestion items that could impact 

construction or design. 

3. Major and specialty equipment quotes were solicited from third party 

contractors based on specific flow conditions and design requirements. The 

quoted components include material costs and installation estimates for: 

(i) Thermal Oxidizers and Acid-Gas Scrubbers. 

(ii) Ductwork from emission sources to oxidizers. 

4. The other direct cost items (pumps, piping, instrumentation, foundations, etc.) 

were estimated in detail using proprietary ExxonMobil estimating methods 

(based on data and experience from previous and on-going projects). 

5. The indirect costs and contingency were then estimated by using 

ExxonMobil’s estimating methods for similar projects. Contingency is added 

based on estimate accuracy studies of previous projects at this projects 

development stage. 

Some of these activities went beyond steps normally taken at this early phase of 

project development. Site visits are not usually made at this stage of a project, 

but it was deemed necessary because of the complexities associated with the 

installation and connection of the new equipment to an operating plant with 

limited space available.

D. Exxon Mobil has experience in the cost of installation and operation of 

thermal oxidizers at other locations; actual project costs support 

ExxonMobil’s current control cost estimates and highlights how EPA’s 

estimates are significantly understated. 

 Actual cost information was collected for thermal oxidizer projects completed by 

ExxonMobil in the last 10 years. These projects were completed around the 

world, so, for comparison purposes, these costs were converted from their 

source location and source time frame to a comparable cost in 2013 in Baytown, 

Texas. This conversion was made using ExxonMobil proprietary factors based 

on regularly published cost updates. These cost updates are produced from 

ExxonMobil’s worldwide project experience and regular surveys of Engineering / 

Procurement / Construction contractors. 

 Each cost total represents the total cost of the thermal oxidizer project scope. 

This means it includes the material, labor, and engineering of the thermal 

oxidizer itself and all the associated ducting, piping, electrical and instrument 

components, and other support facilities. 
31

Summary of Actual Project Capital Costs 

Project 

Year of 

Installation 

Airflow 

(kscfm) 

VOC 

(lb/hr) 

Capital 

Cost ($M) 

Site A: U.S. 2002 57 206.0 14.2 

 

Site B: U.S. 2002 40 88.4 9.5 

Site C: U.S. 2005 20 25.8 7.3 

Site D: Europe 

 2003 / 

 2005 60 287.0 12.1 

 

Note: M = million 

 More detailed information on these projects, including location, is included in the 

CBI letter. 

 Each project is different due to such factors as different plant layouts, the 

availability of utilities, and plant specific requirements. These four projects 

represent a good mix of possible thermal oxidizer projects. In summary, the 

installed costs of thermal oxidizers at four locations shows a typical actual cost of 

$7M to $14M, which is comparable to, and supports, the cost estimates 

developed for the controls potentially required by EPA’s P&R1 proposal. Our 

actual experience also further highlights how EPA’s control cost estimates are 

deficient and significantly understated. 

E. Equipment selection for n-hexane emissions control 

 To support project development, a technology selection assessment was 

prepared to optimize control technology effectiveness and costs for the intended 

service. This section, and the following, provide background on the assessment.

 The back-end emission streams from the Butyl and Halobutyl finishing operations 

are characterized as having a high volume of ambient air with a range of 20,000 - 

80,000 acfm (actual cubic feet per minute) and with very low concentrations of 

VOCs (volatile organic compounds) with a range of 40 to 500 ppm (parts per 

million) by volume. Also, these streams approach saturation with moisture and 

contain significant quantities of sticky particulates. The particulates require 

filtration to prevent down-stream plugging of ducting and control equipment. A 

portion of the contained moisture condenses in the ducting, requiring removal, 

with the remaining portion staying in the process stream and passing through the 

control equipment. The control equipment selection requires that all these issues 

be considered so that the chosen technology can meet a high VOC destruction 

efficiency and reasonable service factor under these conditions. 

 Control of the VOCs contained in this stream requires addition of a considerable 

quantity of energy, in the form of natural gas, to achieve the desired thermal 
32

destruction of 98%. Not only is the large volume of air being heated, but the 

contained water vapor must also be raised to a temperature of 1450°F - 1550°F 

to achieve destruction of the contained VOCs. The control equipment selection 

therefore must accomplish these requirements with significant thermal efficiency 

and contribute minimum NOx emissions. Low NOx emissions are of particular 

importance in the Baton Rouge and Baytown areas where ozone attainment is an 

issue. 

 For this set of conditions, a Regenerative Thermal Oxidizer (RTO) is the 

technology of choice. A well-designed RTO has a destruction efficiency that can 

meet 98%. Also, the contained media can achieve a thermal efficiency of 95% 

which reduces the addition of natural gas by 95% as opposed to a conventional 

thermal oxidizer. The addition of natural gas is typically achieved by injection just 

upstream of the media bed. This injection point has the benefit of producing very 

low NOx emissions because the incoming process stream is preheated to a 

temperature that approaches ignition by the heat reclaimed from the destructed 

VOCs. A normal thermal oxidizer will have an ignition burner that will have a 

flame temperature that can approach 3000°F and will produce significant 

quantities of NOx even with the use of low NOx burners because the burner must 

provide all the heat required to bring the air stream to VOC destruction 

temperatures. Even a recuperative thermal oxidizer, which has some heat 

recovery, requires much more fuel combustion than an RTO, and therefore 

generates much more NOx.. 

 Another desirable feature of a RTO is its ability to minimize the service factor 

impact of the significant amount of water vapor that is contained in the process 

stream. An RTO design has a limited amount of surface area that falls below the 

dew point temperature of the trace amounts of acid gases that may be present in 

the destructed gas stream, thereby significantly reducing corrosion in the thermal 

oxidizer versus a standard design. 

 The presence of trace amounts of acid gases and moisture requires that 

significant portions of the oxidizer and collection system be fabricated from metal 

alloys that can resist corrosion attack at temperatures that range from ambient to 

those in excess of 1500°F. Therefore, the ducting that connects the individual 

collection hoods to the RTO will be made of 304 SS (Stainless Steel). The inlet 

and outlet ducting manifolds are capable of seeing temperatures up to 600°F and 

will use a combination of 316 SS to RA 2205 (Royal Alloy). The media support 

beams within the RTO experience a wide swing of temperatures and will be 

fabricated from AL 6XN alloy. All of these materials are selected specific to the 

conditions they will experience. 

F. Equipment selection for MeCl/HCl emissions control 

The front-end emission streams from the Butyl Rubber and Halobutyl Rubber 

polymerization operations are characterized as having highly variable flow rates 

and high, but very variable, concentrations of Methyl Chloride (MeCl) and very 

low concentrations of other compounds. Therefore, the control equipment 
33

selection requires that additional ambient dilution air be introduced to achieve the 

desired 98% destruction efficiency. 

 Control of the MeCl contained in these streams also requires energy addition, in 

the form of natural gas, to reliably accomplish thermal destruction as the MeCl 

content and stream flow can vary greatly (e.g., <1 to > 800 lb/hr MeCl and 19 to 

>3900 lbs/hr stream flow at the Baytown Chemical Plant). Each process stream 

must be raised to a temperature of ~1400°F to achieve destruction. Following 

thermal oxidation the produced acid gases (HCl) will require cooling and 

scrubbing with a sodium hydroxide and water solution to neutralize the 

hydrochloric acid. The control equipment selection, therefore, must accomplish 

these requirements with significant thermal efficiency and contribute minimum 

NOx emissions to the atmosphere. 

 Selection of a Recuperative Thermal Oxidizer (RCO) followed by a quench and 

acid gas scrubber are the technologies of choice for this situation. A welldesigned RCO and acid gas scrubber can achieve the specified organic HAP 

destruction (98%) and HCl removal (99%). Also, the heat exchange surfaces 

can reclaim 60 to 65% of the heat produced during oxidation for use in preheating the combustion air and process gas stream. This will reduce the need 

for additional natural gas when low concentrations of MeCl are present in the 

feed stream. The ability to preheat a combustion air stream has the added 

benefit of producing very low NOx emissions because the incoming process 

stream and air mixture is preheated to a temperature that approaches ignition by 

the heat reclaimed from the oxidized MeCl. A normal thermal oxidizer will have a 

fired burner that will have a high flame temperature and will produce significant 

quantities of NOx, even with the use of low NOx burners. 

 Because of corrosion concerns, the RCO will be fabricated from Inconel 625 and 

316 SS (Stainless Steel) the quench section will be made of Hastelloy C-276, the 

acid gas scrubber will be FRP (Fiberglass Reinforced Polyester) and the induced 

draft fan and discharge stack will be 304 SS. All of these materials are selected 

specific to the conditions they will experience.

G. Summary of capital costs for proposed control devices. 

The table below summarizes ExxonMobil’s estimates for the controls identified in 

the proposal. For comparison purposes, a combined Halobutyl Rubber and EPR 

front-end control system was estimated, since that is the basis for EPA’s beyondthe-floor decision, though as we discuss in Section V, a shared system is neither 

legally or practically viable. Where we have evaluated the cost-effectiveness of 

the realistic case of separate controls, we have scaled this cost estimate for the 

combined unit using the design flows and well-established scaling approaches. 

The total capital cost covers the capital cost of engineering, buying, and installing 

the selected control device and all auxiliary items. These numbers are based on 

installation in Baytown or Baton Rouge and a 2013 mechanical completion date. 

They exclude Project Services Costs, which are discussed in the CBI letter. The 

CBI letter also includes details on the cost estimates, including vendor quotes.
34

 Controls Equipment 

 RTO RCO Scrubber

Design Flow 

(scfm) 

Total Capital 

Cost $M 

Baytown Butyl Front-End 

Controls

 

5,700 13.0 

Baton Rouge Halobutyl and 

EPR Front-End Controls

 

2,650 10.6 

Baytown Butyl Back-End 

Controls 

 

70,000 10.0 

Baton Rouge Halobutyl 

Back-End Controls 

 

80,000 14.5 

H. Summary of operating costs for proposed control devices. 

In addition to project costs there will be ongoing operating costs associated with 

the facilities. These costs typically include: 

1. Energy-related (natural gas and electricity) 

2. Maintenance (routine and preventive maintenance; materials and labor) 

3. Operating labor 

4. Other utilities (wastewater, steam, plant air, nitrogen) 

5. Other costs such as administrative, taxes, insurance, overhead 

 The following table summarizes the major operating costs for the four sets of 

controls. Details on the cost estimate basis are included in the CBI letter. 
35

Operating Costs, k$ 

Cost 

Category 

Baton Rouge 

Halobutyl and 

EPR FrontEnd Controls 

Baytown Butyl 

Front-End 

Controls 

Baton Rouge 

Halobutyl BackEnd Controls 

Baytown Butyl 

Back-End 

Controls 

Natural Gas 52.0 11.8 

 

 71.0 23.7 

Electricity 13.2 17.6 301.9 114.3 

Maintenance 120.0 120.0 60.0 15.0 

Operations 39.5 39.5 26.3 6.6 

 

Total 224.7 188.9 459.2 159.5 

Note: k = thousand 

I. EPA’s capital and operating cost estimates for the controls proposed have 

major deficiencies and significantly underestimated the expected costs. 

 New Plant Installations versus Retrofits

 EPA’s pollution control cost manual states, 

“All costs are for new plant installations; no retrofit cost considerations are 

included.” 

EPA Air Pollution Control Cost Manual - Sixth Edition (EPA 452/B-02-001). 

Entire Document. Page 528/752. 

 The installation of a thermal oxidizer in an existing plant poses a number of 

challenges that the EPA Manual and method do not address. 

1. Oxidizer Location. Construction of a new unit allows for optimization of the 

plot plan. This means that the designer can shuffle equipment around and 

position an oxidizer very close to the emission sources. Because the 

proposed controls will be installed in existing units with limited space to place 

equipment, the oxidizers will have to be located at least 300 feet from the 

emission sources. This leads to a significant cost in ducting to bring the 

emissions to the oxidizers. 

2. Working in and around an Operating Unit. Working near an online unit 

creates a number of delays that slow down work and cost more money. 

These include such things as a more thorough work-permitting procedure, 

interruptions from the plant (events such as gas leaks), extra safety 

requirements, and long distances between the work areas and material 

staging areas. These delays can reduce productivity by up to 30%. 
36

3. Tie-ins. When collecting emissions from existing sources, connecting the 

new equipment or piping to existing equipment or piping is referred to as a 

tie-in. Tie-ins to operating units require extra planning and engineering, as 

well as extra labor to make sure the connection occurs smoothly. Many of 

the tie-ins for these projects will be hot-taps, which are especially difficult. 

Hot-taps involve connecting a new pipe to an existing one that is in operation 

without disturbing the operation of the existing pipe. 

4. Limited Utilities Available. Adding an oxidizer to an existing unit requires 

electricity, natural gas, steam, and other utilities. A unit seldom has spare 

capacity for all the utilities needed; therefore extra capacity has to be built. 

For example, if all the electrical breakers in a substation are in use, an 

additional unit may need to be added to power just a few pumps or fans. 

5. Engineering. Significant additional engineering will be required not only for 

the new facilities to be installed, but also to address the impact on existing 

equipment and operations. 

 Equipment Costs – RCO versus RTO

For the back-end controls, ExxonMobil typically uses Regenerative Thermal 

Oxidizers (RTOs) versus Recuperative Thermal Oxidizers (RCOs). RTOs 

require a higher initial investment, but make up for it in fuel savings. This is 

because RTOs can achieve up to 95% heat recovery. More details on the 

selection of RTOs can be found in the equipment selection discussion at the start 

of this section. 

The EPA estimate assumed a direct flame incinerator (0% heat recovery) for the 

back-end controls at the Baytown Butyl Plant, and a recuperative thermal 

oxidizer (70% heat recovery) for the Baton Rouge Halobutyl plant. This led to 

lower capital equipment costs than if they had used their methods to estimate 

RTOs. The table below shows what the equipment cost would be for RTOs 

based on EPA’s Cost Manual. 

 

Baytown 

Butyl 

Baton 

Rouge 

Halobutyl 

Total Gas Flow (scfm) 13,037 28,096 

0% Heat Recovery Incinerator 95,876 

70% Heat Recovery Incinerator 276,310 

Regenerative Thermal Oxidizer1371,238 545,471 

Percent Increase 387% 197% 

1

 These calculations come directly from EPA’s Air Pollution Control Cost Manual. 
37

Auxiliary Equipment

According to the EPA’s Control Cost Manual, the total Purchased Equipment 

Cost (PEC) is the sum of the Equipment Cost (EC) plus any auxiliary equipment, 

such as ducting or pumps. In the EPA’s cost estimate, no auxiliary equipment 

was added for the incinerators and only pumps and packing were added for the 

scrubbers. 

Because of limited space close to the emission sources, the incinerators will be 

located 300 ft from the emission sources for 3 of the 4 projects, and 1,200 ft 

away for the Baytown Butyl front-end controls. This results in a significant 

amount of ducting that was not included in the EPA estimate. 

In addition to pumps and packing, the scrubbers will require a storage drum to 

hold a 1 hour supply of the scrubbing liquid and a heat exchanger to keep the 

scrubbing liquid cool. The storage drum and heat exchanger add up to a 

significant cost that was not included in the EPA estimate. 

 Total Capital Investment Factor

To estimate the Total Capital Investment, the EPA’s Cost Manual first generates 

a purchased equipment cost, PEC. The PEC is then multiplied by a total capital 

investment factor to generate the Total Capital Investment. According to the 

manual, these factors are 1.61 for incinerators and 2.20 for acid gas scrubbers. 

In the EPA’s estimate, a factor of 1.25 was used for the incinerators that were 

smaller than 20,000 scfm. The table below shows the factors in use. 

EPA Cost Estimate Total Investment Factors 

 Front-End Controls Back-End Controls 

 

Baytown 

Butyl 

Baton 

Rouge 

Halobutyl 

and EPR 

Baytown 

Butyl 

Baton 

Rouge 

Halobutyl 

Incinerator 

Purchased Equipment 

Cost 138,337 385,012 187,671 590,943

Factor x 1.25 x 1.25 x 1.25 x 1.61 

Total Capital Cost 172,921 481,264 234,589 951,419

Scrubber 

Purchased Equipment 

Cost 225,636 290,516 

Factor x 2.20 x 2.20 

Total Capital Cost 496,400 639,136 

 
38

Compared to typical ExxonMobil projects, these factors are quite low. A typical 

ExxonMobil project would have a ratio of 4 or 5 rather than 1.61 or 2.20. The 

reason for this difference is the EPA method assumes small indirect costs, 

whereas ExxonMobil’s project experience indicates these costs are very 

significant. 

According to the EPA Cost Manual, indirect costs should be 31% of the 

purchased equipment cost for an incinerator, and 35% for a scrubber. Indirect 

costs consist of engineering, construction supervision, scaffolding, construction 

equipment, and other field expenses. EPA also includes the estimate 

contingency in the indirect cost category. In a typical ExxonMobil project, the 

indirect costs, engineering, and contingency is 200% to 300% of the purchased 

equipment cost. 

ExxonMobil projects require a significant amount of engineering. Engineering for 

new construction in an operating plant containing hydrocarbons is a tedious and 

complicated process. It is essential to design a system that is low risk and very 

safe. Impact on existing facilities requires additional engineering. 

The contingency for this estimate at this stage is relatively high because of 

uncertainties in scope. Small changes in design or execution strategy could have 

a very large impact on cost. At this early point in the project, numerous 

assumptions are made and changes/developments in scope are expected. For 

example, if it is determined that another emission source will have to be added to 

the control device, it will impact the RTO size, ducting, and utility requirements. 

These small changes actually have a large impact on the cost, especially as the 

project gets closer to completion. A change late in a project has a large cost 

impact because it can result in a significant amount of rework. 

In summary, the EPA estimate is inadequate for four reasons: 

1. It does not include retrofit considerations. 

2. It assumes that recuperative thermal oxidizers will be installed for back-end 

controls. ExxonMobil typically uses regenerative thermal oxidizers for these 

controls because the additional investment is justified by the operating cost 

savings and the lower NOx emissions. 

3. It does not include the significant costs for auxiliary equipment, such as 

ducting, storage drums, or heat exchangers. 

4. The total capital investment factor used is much too low for a major retrofit 

project and does not produce enough cost for indirect costs, engineering, or 

contingencies. It does not reflect the safety and other facility requirements 

necessary in an existing operating plant. 
39

VII. Compliance Time 

A. EPA should provide 4 years to comply with emission limits that require 

capital investment to install controls; the automatic one year extension 

should be incorporated into the final rule. 

EPA’s rulemakings related to the Boiler/Process Heater MACT, other air toxics 

rules, and utility air rules will trigger a significant demand for combustion 

engineers, company resources, materials, and construction resources to meet 

those compliance deadlines. This proposal provides three years for compliance 

where controls will have to be installed. As EPA has assumed in its supporting 

analyses, these will be combustion controls. While three years is oftentimes 

reasonable for installing such controls, it is inadequate in this case due to the 

widespread demand for combustion-related resources. The Agency should 

provide, in the final rule, an additional one year of compliance time for any unit 

subject to an emission limit under this regulation. This additional one-year 

extension is pursuant to CAA § 112(i)(3)(B), and 40 CFR 63.6(i). 

B. EPA should allow four years for compliance even when the back-end 

emission limit is set at the floor and no beyond-the floor controls are 

required. 

 EPA proposes that for the Halobutyl Rubber subcategory a back-end emission 

limit that would be based on the emissions data provided for a single year and no 

beyond-the floor controls would be required. Based on this, and an expectation 

that no capital investment would be required, EPA proposes a compliance date 

one year from the date of the final rule. However, the no capital investment 

assumption is potentially in error, depending on the final rule for the following 

reasons: 

1. The proposed emission limit for Halobutyl Rubber was based on one year of 

data with no allowance for variability. As we indicate in our discussion of 

variability in section IV of these comments, the emission factor derived from 

that year’s data must be increased by at least 43% to reflect the historic 

variability of emissions from that unit. Without that adjustment, in most years 

the unit will exceed the floor limit and it will take considerable time and 

potentially capital investment, to ensure the emission limit can be met for all 

12-month periods. 

2. The removal of the existing startup and shutdown provisions and the failure to 

include reasonable replacements will force the development of new work 

practices and may require added capital investment for further controls given 

the obligation of compliance at all times. 

3. In addition, the proposed rule does not currently consider the state permit 

conditions available to the sites to allow for maintenance on the existing 

RTOs. This effectively tightens the standard applicable to the Halobutyl unit 

and makes it likely that upgrades to the existing RTO or other capital 

investment will be required. 
40

C. EPA should clarify that, in the absence of allowing four years as 

recommended above, for back-end emission limits not requiring controls 

the first compliance demonstration is two years (24 months) following the 

date of the final rule. 

For back-end process provisions that EPA anticipates would not require controls, 

it is proposed that compliance with rule requirements be required no later than 

one year from the date of publication of the final rule. The compliance 

determination in § 63.495(g)(5) says: “each month, divide the total mass of 

organic HAP emitted for the 12-month period by the total mass of elastomer 

produced during the 12-month period.” Thus, as compliance is required 

beginning one year after rule publication, data collection begins in the 13th month. 

Since compliance is based on annual emissions (53 Mg/yr for Halobutyl in the 

proposal) this requires data to be collected for 12 months after the compliance 

date before a compliance determination can be made, and then the 

determination is made every month thereafter. So in effect, compliance can only 

be demonstrated after 24 months from the date of the final rule. 

There has been some indication that EPA believes that the first month’s data 

(13th month from the date of the final rule) should be used to demonstrate 

compliance, and then, after two months, the two month emissions and production 

data should be used to determine compliance, etc. Such an interpretation would 

be patently inconsistent with the proposed rule language and the emission limit, 

which is a rolling 12-month limit. Using performance from shorter time frames to 

compare against a 12-month emission limit effectively increases the stringency of 

the standard by eliminating monthly variability. For example, the first month 

could have higher than normal emissions due to grade slate. The proposed rule 

emission limit did not factor in monthly variability nor did the rule consider the 

potential added capital investment required to meet a more stringent limit. In the 

final rule EPA should clarify that, in the absence of allowing four years as 

recommended above, for emission limits that EPA believes will not require 

controls, the first compliance demonstration is two years (24 months) following 

the date of the final rule. 

D. The timing of the backend compliance calculation needs to be corrected. 

The regulatory language in § 63.495(g)(5) requires calculating the 12-month 

average emissions for Butyl and Halobutyl back-end process emissions. 

However, the proposed language requires that you do the calculation before the 

end of the 12th month. The rule language says: “each month, divide the total 

mass of organic HAP emitted for the 12-month period by the total mass of 

elastomer produced during the 12-month period.” This is impractical since there 

is additional production and emissions occurring right up until the end of the 

month. The regulatory language should be revised to provide that each month 

you calculate the 12-month average emissions and production for the previous 

calendar 12-month period. 

E. EPA should clarify that the compliance date related to removal of the 

Startup/ Shutdown/ Malfunction provisions is also four years. 
41

In the proposed rule EPA did not indicate the compliance date related to the 

removal of the Startup/ Shutdown/ Malfunction provisions. Given that potential 

emissions during startup and shutdown periods were not incorporated into the 

1996 standard, facilities may have to invest capital to improve or add controls and 

certainly will have to develop new work practices, test them and train personnel. 

As a result, they would need up to four years for project construction and 

implementation and to implement needed work practice changes. Startups and 

shutdowns occur infrequently. In fact, there is likely to be only one major unit 

turnaround in a four year period. Thus, even work practices will take an extended 

time to develop and test, since sources must wait for planned startups and 

shutdowns to determine if a particular work practice meets the newly imposed 

emission limits. This is a particular concern for the back-end emission limits, 

since those are 12-month averages. Therefore, it takes up to 12 months to 

determine if a startup or shutdown has caused the emission limit to be exceeded. 

VIII. Startup/Shutdown/Malfunction (SSM) and Affirmative Defense 

 

A. EPA has misread Sierra Club v. EPA

EPA asserts that its treatment of excess emissions during SSM events in the 

proposed rule is consistent with the D.C. Circuit’s decision in Sierra Club v. EPA, 

551 F.3d 1019, which vacated the exemption for excess emissions during SSM 

events contained in the 40 C.F.R. Part 63 General Provisions for emission 

standards for hazardous air pollutants under § 112. EPA claims that the D.C. 

Circuit’s interpretation of the definition of “emission standards” requires EPA to 

apply MACT emission standards at all times, compelling EPA to eliminate the SSM 

exemption from subpart U. 75 Fed. Reg. at 65074. While that statement may be 

literally accurate — “exempting” emissions entirely, so that they would not be 

subject to any emission standard, would not satisfy the requirement of the Sierra 

Club panel — the opinion does not preclude EPA from applying a different 

emissions standard during SSM events than applies during normal operations. In 

fact, the opinion acknowledges that CAA § 302(k)’s “inclusion of [the] broad 

phrase” “any requirement relating to the operation or maintenance of a source to 

assure continuous emission reduction” in the definition of “emission standard” 

suggests that EPA need not “necessarily continuously apply a single standard.” 

551 F.3d at 1027. See also id. at 1021 ("accepting that 'continuous' for purposes 

of the definition of 'emission standards' under CAA section 302(k) does not mean 

unchanging"); id. (referring to "the CAA's requirement that some section 112 

standard apply continuously") (emphasis added). 

Thus, EPA cannot hide behind the Sierra Club decision as a justification for 

ignoring the inability of even the “best performers” to achieve the proposed 

emission standards during SSM events. If EPA sets the emission standards based 

on the “best performing 12% of units in the category,” those limitations must on 

average be “achieved” by the best performers. An emission limitation that applies 

during SSM events has not been demonstrated to be “achieved” by the bestperforming 12% of units in the category” unless EPA can show that those best 

performers actually meet that emission limitation during SSM events. 
42

The D.C. Circuit also has recognized that standards based on what sources 

achieve must account for the limitations inherent in the technology used to reduce 

emissions. For example, in a case reviewing NSPS under § 111 of the CAA, 

Portland Cement Ass’n v. Ruckelshaus, 486 F.2d 375, 398 (D.C. Cir. 1973), the 

court acknowledged that “’startup’ and ‘upset’ conditions due to plant or emission 

device malfunction, is an inescapable aspect of industrial life and that allowance 

must be made for such factors in the standards that are promulgated.” Id. at 399; 

see National Lime Ass’n v. EPA, 627 F.2d 416, 431 n.46 (D.C. Cir. 1980) (noting 

that “a uniform standard must be capable of being met under most adverse 

conditions which can reasonably be expected to recur”). The D.C. Circuit 

acknowledged this same principle when reviewing emission standards for new 

sources in the medical waste incinerator rule under CAA § 129 in Sierra Club v. 

EPA, 167 F.3d 658 (D.C. Cir. 1999). In that case, while the court did not find the 

record sufficient to support EPA’s approach for new sources, the D.C. Circuit did 

not object to a standard-setting approach which would account for the performance 

of technology under the “worst reasonably foreseeable circumstances.” See id. at 

665. Furthermore, the D.C. Circuit reiterated the principle in National Lime that 

“where a statute requires that a standard be ‘achievable,’ it must be achievable 

‘under the most adverse circumstances which can reasonably be expected to 

recur.’” Id. at 665 (citing National Lime Ass’n v. EPA, 627 F.2d at 431 n.46). 

EPA’s MACT approach in the proposed P&R1 NESHAP ignores these 

longstanding principles by applying the same set of standards at all times, 

including SSM. 

Courts have reached a similar conclusion when considering analogous Clean 

Water Act requirements that EPA establish technology-based effluent limitations 

based on the best available control technology. Knowing that there would be 

periods where a discharger, even with “exemplary use of” the identified best 

technology, would exceed the effluent limitations because of conditions “beyond 

the control of the permit holder,” EPA violated the Clean Water Act by failing to 

provide an “upset provision” to address those periods. Marathon Oil Co. v. EPA, 

564 F.2d 1253, 1273-74 (9th Cir. 1977). See also, e.g., NRDC v. EPA, 859 F.2d at 

207 (distinguishing between technology-based effluent limitations, where some 

provision for “upsets” is required, and water-quality-based effluent limitations, 

which are tied to achieving water quality standards rather than based on available 

technology, and therefore need not include an upset provision).5

As noted above, the Sierra Club panel did not prevent EPA from adopting emission 

standards that are different for SSM periods than for normal operation. Nor did it 

conclude that EPA is barred from using a “requirement relating to the operation or 

maintenance of a source to assure continuous emission reduction” as the emission 

standard that applies during such events. See 551 F.3d at 1027. All that decision 

 

5 Weyerhaeuser Co. v. Costle, 590 F. 2d 1011 D.C. Cir. 1078), does not support EPA’s position. In that case, the 

court was discussing a “technology forcing” standard, rather than one, like MACT and NSPS, that is to be based on 

what is already being “achieved” or has been demonstrated to be achievable. Also, the decision came long before 

NRDC v. EPA, 859 F.2d 156 (D.C. Cir. 1988) which, as noted above, affirmed the need for an upset provision to

address circumstances where compliance with effluent limitations is impossible through no fault of the permittee, and 

which endorsed Marathon Oil. 
43

rejected was EPA’s assertion that it had discretion to decide not to impose any 

emission standard whatsoever during SSM periods. See id. at 1027-28, 1030 

(noting that EPA was not claiming that the General Provisions SSM exemption was 

either an emission standard under § 112(d) or a design, equipment, work practice, 

or operational standard under § 112(h)).6 

B. EPA should propose a separate emission limit or apply work practice 

standards during periods of SSM to appropriately recognize the operating 

and emission differences during these periods. 

EPA’s failure to provide specific standards applicable to SSM periods in the 

proposed P&R1 NESHAP is contrary to the statute’s requirement that the 

standards established under § 112(d) be “achievable.” Furthermore, EPA’s data 

analysis used in developing the proposed standard does not reflect the 

consideration of emissions during startup and shutdown periods. Although the 

proposed rule contains a discussion regarding EPA’s position with respect to 

considering malfunction emissions in developing § 112(d) standards, 75 Fed. Reg. 

at 65074, which these comments address below, EPA appears to presume that 

startup and shutdown emissions will comply with the existing and proposed 

standards for normal operations. While acknowledging that “[p]eriods of startup ... 

and shutdown are all predictable and routine aspects of a source’s operations,” id., 

EPA’s proposal provides no information that startup and shutdown data were 

considered in EPA’s floor-setting process. 

EPA has two choices to address startup and shutdown emissions. First, EPA 

could promulgate numerical emission standards that apply to startup and shutdown 

emissions. To promulgate such a standard, EPA needs to have data to determine 

which facilities are the best performing sources during startup and shutdown 

periods. EPA either needs to identify or collect this data and propose one or more 

standards applicable during startup and/or shutdown. 

Second, given the current lack of and difficulty in measuring and collecting data for 

startup and shutdown emissions, it would be appropriate for EPA to set work 

practices for these events. Section 112(h) allows EPA to set work practice 

standards for situations where “it is not feasible in the judgment of the 

Administrator to prescribe or enforce an emission standard,” defined as any 

situation where “the application of measurement methodology to a particular class 

of sources is not practicable due to technological and economic limitations.” §§ 

112(h)(1)-(2). Gathering data from startup and shutdown periods would be 

challenging given the often brief and variable nature of these periods, the lack of 

proven methodologies for measuring such emissions, as well as the need to define 

the exact time period for what is considered “startup” and/or “shutdown” and the 

extremely variable array of equipment that could be involved in startups and 

 

6

 The statement in the majority opinion that “Congress gave no indication that it intended the application of MACT 

standards to vary based on different time periods,” 551 F.3d at 1028: (1) is contradicted by other statements in the 

opinion, referenced above, that a MACT standard need not continuously apply a single emission limitation, (2) is 

dicta, because that was not the situation presented by the challenge regulations and argued by EPA, (3) ignores the 

extensive case law about technology-based limitations referenced above, and (4) does not in any event say that the 

CAA precludes EPA from adopting different emission limitations that apply during SSM events. 
44

shutdowns. A work practice approach for these periods would satisfy both the 

statute’s requirement that MACT standards be “achievable” and the requirement 

that there be a MACT standard applicable at all times. 

A work practice approach for these periods also would be consistent with EPA’s 

recently promulgated MACT standards for compression ignition reciprocating 

internal combustion engines (CI-RICE). See National Emission Standards for 

Hazardous Air Pollutants for Reciprocating Internal Combustion Engines, Final 

Rule, 75 Fed. Reg. 9648 (Mar. 3, 2010). EPA finalized work practice standards for 

startup of such engines because the agency determined that it was “not feasible to 

finalize numerical emission standards that would apply during startup because the 

application of measurement methodology to this operation is not practicable due to 

technological and economic limitations.” Id. at 9656. According to EPA, applicable 

test methods that would be needed to measure during these events “do not 

respond adequately to the relatively short term and highly variable exhaust gas 

characteristics occurring during these periods.” Id. at 9665. 

For similar reasons, EPA should set work practice standards to apply to 

malfunction periods. EPA argues in the preamble to the proposed rule that these 

periods should not be considered a “distinct operating mode” and uses this position 

to justify not factoring malfunction emissions into the proposed MACT standards. 

Considering that EPA’s proposed MACT standards are supposed to apply at all 

times, the implication is that periods of malfunction also are covered by the MACT 

standards that apply during normal operations. This directly conflicts with the 

statutory requirement that the MACT standard be “achievable.” 

Given that the data used to develop the P&R1 NESHAP proposal does not 

consider malfunctions despite the fact that EPA claims malfunctions are not a 

separate operating mode from normal operations and that the statute requires that 

the standard be “achievable,” EPA must either reconsider and re-propose the 

MACT standards considering malfunctions or set a separate standard, such as a 

work practice standard to address periods of malfunctions. Section 112(h) allows 

EPA to set work practice standards for situations where “it is not feasible in the 

judgment of the Administrator to prescribe or enforce an emission standard . . . .” 

Similar to startup and shutdown, malfunctions fit with the situations described in 

the definition of “not feasible to prescribe or enforce an emission standard” as any 

situation where “the application of measurement methodology to a particular class 

of sources is not practicable due to technological and economic limitations.” 

Emission testing for malfunctions would be near impossible to conduct given the 

sporadic and unpredictable nature of the events. EPA acknowledges in the 

preamble to the proposed rule that it is “impracticable” to take periods of 

malfunctions into account when setting emissions standards given the “myriad 

different types of malfunctions that can occur across all sources in each source 

category” and that “malfunctions can also vary in frequency, degree, and duration, 

further complicating standard setting” 75 Fed. Reg. at 65074. Section 112(h) work 

practice standards, therefore, are well-suited to address malfunction periods and 

the complexities and challenges surrounding collecting data and establishing 

numerical standards for those events. 
45

An example of an appropriate work practice for SSM periods is one that EPA has 

had in place for many years, development and use of SSM plans. These plans are 

carefully prepared, tied to the specific type of operation, and identify the steps 

necessary to minimize emissions during SSM periods. If warranted, root cause 

analyses could be added to further strengthen the work practice requirement. 

C. The proposed affirmative defense is not a substitute for setting emission 

standards for SSM periods. 

EPA acknowledges that regulated sources sometimes will be unable to comply 

with standards because of malfunctions, even if their equipment is properly 

designed and maintained, through no fault of the source. 75 Fed. Reg. at 65074. 

Rather than promulgate a separate emission standard that eliminates that situation 

during SSM, achievable with the identified best technology, EPA offers instead an 

“affirmative defense.” Inclusion of the affirmative defense would not cure EPA’s 

failure to meet the § 112(d) requirement to set emission standards that are 

achievable during SSM events. 

Even if the proposed affirmative defense were not unreasonably restrictive, as 

discussed below, being able to assert a defense obviously is not the same as 

complying with emission limitations in the first instance, particularly in the case of 

an emission limitation that the CAA requires be achievable. Although a source 

qualifies for the affirmative defense, it may be considered to have violated the 

standards—and may have to report violations, certify noncompliance, etc. 

Assuming a source successfully demonstrates the affirmative defense to penalties, 

the fact remains it has reported a violation of standards and is legally vulnerable. 

It is unclear how the affirmative defense would apply to enforcement actions by 

state and local governments, or to private citizen enforcement actions under CAA 

section 304. While we assume EPA intends the affirmative defense to be available 

in a citizen suit, still: (a) a lay judge, rather than environmental experts at EPA, 

would be assessing the source’s entitlement to the affirmative defense, and (b) it 

appears that the source might be subject to injunctive relief, and could be required 

to pay in the citizen-plaintiff’s attorneys fees, even if the source successfully 

demonstrated that it qualified for the affirmative defense. EPA has not addressed 

these and other apparent limitations and shortcomings of the affirmative defense, 

which make it an entirely inadequate substitute for setting standards that include 

provisions for SSM events. 

Furthermore, there is no legal basis for outright precluding application of an 

affirmative defense to injunctive relief. EPA apparently believes it will encounter 

situations where a facility can qualify for the affirmative defense to civil penalties 

but there will still be some preventive step EPA will be able to require to avoid a 

future exceedance. However, in order to qualify for the affirmative defense in the 

first place, a facility must demonstrate, at a minimum, that it could not have 

reasonably prevented the exceedance. In most if not all cases where the 

affirmative defense applies, there will be no reasonable injunctive relief available. 
46

At a minimum, EPA should state that the affirmative defense applies to civil 

penalties, administrative penalties, and injunctive relief. EPA also should reword 

the affirmative defense, so that it states a person who demonstrates entitlement to 

the affirmative defense “will not be deemed in violation of” the subpart U standards. 

Cf. 40 C.F.R. § 80.613. (stating that persons demonstrating specified defenses 

“will not be deemed in violation” and are not “deemed liable for a violation” of diesel 

fuel sulfur program regulations). 

D. The proposed affirmative defense as written is unreasonable and 

impracticable. 

If EPA refuses to set alternative emission standards that apply during SSM periods 

and continues to rely instead on the proposed affirmative defense, the affirmative 

defense must be substantially modified for it to provide any significant, practical 

value. First, as noted above, the affirmative defense needs to state clearly that a 

source that qualifies for the affirmative defense shall not be deemed to have 

violated the applicable standards during that time. 

Second, the affirmative defense should be available not only for malfunctions, but 

also for excess emissions during startup and shutdown. There is no logical reason 

why a source that experiences excess emissions during startup or shutdown that 

were not reasonably preventable (either because it experienced conditions EPA 

did not anticipate in setting the standards, or because EPA’s assumption about the 

achievability of those standards during startup and shutdown periods was wrong) 

should be excluded from the affirmative defense. 

Third, many aspects of the proposed affirmative defense make it unavailable as a 

practical matter for many if not most malfunctions. As further detailed below, 

several of the conditions for establishing an affirmative defense use phrases that 

are subject to a wide range of interpretations, and that on their face do not 

recognize any need for reasonableness or cost-effectiveness. How will the 

enforcement authority, or a judge, determine whether “proper design” or “better 

operation and maintenance practices” could have prevented a malfunction 

(§ 63.480(j)(4)(i)(A)), whether a recurring malfunction is a result of “inadequate 

design” (id.), whether repairs were made “as expeditiously as possible” (§ 

63.480(j)(4)(i)(B)), whether the source took “all possible steps” to minimize the 

impact of the excess emissions (§ 63.480(j)(4)(i)(E)), and whether emissions 

control systems were operated “if at all possible” (§ 63.480(j)(4)(i)(F))? In many if 

not most cases, it may have been possible to avoid the malfunction, or to do more 

to reduce the magnitude of the excess emissions, if the source had the benefit of 

hind-sight or if the source had spent unreasonable amounts of money or had 

imposed economically impracticable constraints on its operation. The affirmative 

defense, as proposed, leaves open the possibility that a source will be considered 

to be in violation because the enforcement authority decides that in one or more 

respects it would have been “proper” or “possible” for the source to take further 

steps to prevent or minimize the malfunction. 
47

1. The proposed affirmative defense notification and timing requirements are 

unnecessary and unreasonable and thus arbitrarily limit the potential use of 

the affirmative defense. They should be revised. 

Proposed § 63.480(j)(4)(i) says in part, “To establish the affirmative defense 

in any action to enforce such a limit, the owners or operators of facilities must 

timely meet the notification requirements of paragraph (4)(ii) of this 

subsection, ...” 

Proposed § 63.480(j)(4)(ii) provides: 

(ii) Notification. The owner or operator of the facility experiencing an 

exceedance of its emission limit(s) during a malfunction shall notify the 

Administrator by telephone or facsimile (FAX) transmission as soon as 

possible, but no later than 2 business days after the initial occurrence 

of the malfunction, if it wishes to avail itself of an affirmative defense to 

civil penalties for that malfunction. The owner or operator seeking to 

assert an affirmative defense shall also submit a written report to the 

Administrator within 30 days of the initial occurrence of the 

exceedance of the standard in this subpart to demonstrate, with all 

necessary supporting documentation, that it has met the requirements 

set forth in paragraph (4)(i) of this subsection. 

We believe the notification requirements are arbitrary and unreasonable. Sites 

are required to decide within 2 days of the start of any event whether they want 

to use the affirmative defense. There is no apparent reason why EPA needs to 

know within 2 days of an event whether a facility intends to assert an affirmative 

defense. Depending on the circumstances of the event, the first 2 days may be 

critical to responding to and resolving the event. This time period is when a 

facility will be taking actions that demonstrate the facility is entitled to the 

affirmative defense, if necessary, but the facility will not necessarily know within 

2 days whether it indeed will be able to make the required showing. 

In particular, it is unreasonable to require sources to make such a decision 

before knowing whether the event results in an exceedance. Many compliance 

requirements have long averaging times. Daily averages are typical in subpart 

U for continuously monitored parameters. Thus, a source would never have 

more than a day to react to an indicated excursion and to decide if it was due to 

a malfunction and then whether to invoke the affirmative defense provision. If 

the event occurs over an extended period and is not a large change in the 

monitored parameter, there may be no excursion during the first day of the 

event and then the use of the affirmative defense is unreasonably foreclosed. 

Monthly averages are the basis for determining compliance with the stripper 

bottoms limits for EPR units. In the extreme, the proposed back-end process 

vent emission limits for Butyl and Halobutyl are 12-month rolling averages. 

Thus, a subpart U source often will not know if a particular event will cause a 

deviation from these standards for as long as one month and almost never 

within two days. The time period for meeting the affirmative defense 
48

requirements should start with the date the site determined that there was an 

exceedance, rather than from the start of the event. 

Additionally, it may take time to investigate an event and determine if all of the 

criteria for a malfunction and the affirmative defense are met. In fact, as we 

discuss below, some of the criteria for using the affirmative defense (such as 

performing a root cause analysis) often cannot be completed in 30 days, much 

less 2 days. Investigations to determine if an event meets the malfunction 

criteria often cannot safely start until an event is over, because operating 

personnel are reacting to the event, the equipment cannot be investigated until 

the situation is stable and technical expertise must be gathered. 

There are already many mechanisms at the Federal and State level to make 

immediate notifications of excess emission events to assure the public safety 

and health are protected. Thus, the proposed notification requirements in 

P&R1 are only important in providing adequate time for use of administrative 

proceedings and additional time for reporting imposes no public health or safety 

concern or serves any enforcement purpose. Currently, excursions from 

subpart U requirements, including those due to malfunctions, are reported to 

EPA in the subpart U semi-annual report. In many cases, it would be obvious to 

the enforcement authority, based on the kind of malfunction or deviation reports 

that sources already submit under many air programs, that an exceedance of 

the proposed standards resulted from an unforeseen and unavoidable 

equipment failure or process upset. It is extremely inefficient and burdensome 

for both sources and regulators to require a complete justification of the 

affirmative defense before the enforcement authority has indicated any need for 

further investigation. The 2-day notification requirement should be deleted. 

The 30-day demonstration requirement also must be extended. Allowing only 

30 days to provide the kind of extensive documentation required by the 

affirmative defense as currently written, including a completed root cause 

analysis (RCA), is arbitrary and unreasonable and frequently impossible. For 

major events, it can take weeks and sometimes months to pull together a team 

of experts and complete a RCA. In order to provide adequate time for the more 

complicated malfunction situations and RCAs, the requirement should be to 

submit a written report demonstrating entitlement to the affirmative defense 

within 180 days of determining that there was an exceedance due to a 

malfunction. Alternatively, based on our experience, 90 days is the minimum 

time that should be required, but in that case, the rule must allow for an 

extension of up to 180 days for more complicated situations. 

Finally, related to the RCA requirement, EPA should clarify that the requirement 

to perform a RCA “to determine, correct, and eliminate the primary causes of 

the malfunction” does not require that identified corrective actions be completed 

within the demonstration period. Long- term corrective action can require 

facility modifications that can take years to design and execute or procedural 

changes that can take months to safely implement. 
49

For these reasons, we recommend EPA delete the 2-day initial notification 

requirement as unnecessary, leaving in place only a 180-day written 

demonstration requirement. We believe the initial notification of the decision to 

use the affirmative defense should be on the same schedule as providing the 

supporting information, and that time should start when the source determines 

that there was an exceedance and that that exceedance was due to a 

malfunction. 

We recommend that § 63.480(j)(4)(ii) be revised as follows. 

(ii) Notification. The owner or operator of the facility experiencing an 

exceedance of its emission limit(s) during a malfunction shall notify the 

Administrator by telephone or facsimile (FAX) transmission as soon as 

possible, but no later than 2 business days after the initial occurrence of 

the malfunction, if it wishes to avail itself of an affirmative defense to 

civil penalties for that malfunction. The owner or operator seeking to 

assert an affirmative defense shall also submit a written report to the 

Administrator within 45 180 days of the initial occurrence of the 

exceedance of the standard in this subpart determining that an 

exceedance has occurred to demonstrate, with all necessary supporting 

documentation, that it has met the requirements set forth in paragraph 

(4)(i) of this subsection. 

2. Proposed § 63.480(j)(4)(i)(A) is arbitrary and unreasonably vague and can 

potentially never be met. Limiting the use of the affirmative defense to a 

subset of malfunctions is unjustified and unexplained and should be corrected. 

Proposed § 63.480(j)(4)(i)(A) specifies what has to be proven to use the 

affirmative defense. It states: 

The excess emissions were caused by a sudden, short, infrequent, and 

unavoidable failure of air pollution control and monitoring equipment, or a 

process to operate in a normal and usual manner; and could not have been 

prevented through careful planning, proper design, or better operation and 

maintenance practices; and did not stem from any activity or event that 

could have been foreseen and avoided, or planned for; and were not part of 

a recurring pattern indicative of inadequate design, operation, or 

maintenance; 

Under subpart U, the malfunction definition from 40 CFR § 63.2 applies. That 

definition is: 

Malfunction means any 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 which causes, or has the potential to cause, the emission 

limitations in an applicable standard to be exceeded. Failures that are 

caused in part by poor maintenance or careless operation are not 

malfunctions. 
50

Thus, the proposed first sentence of § 63.480(j)(4)(i)(A) only permits 

application of the affirmative defense to a subset of malfunctions, i.e., those 

that are “short” and those that are “unavoidable” (as opposed to “not 

reasonably preventable.”) The criteria for using the affirmative defense should 

be identical to the criteria for a malfunction in the malfunction definition. Any 

differences are arbitrary and capricious and not supported by the record. 

In addition to the criteria from the malfunction definition, § 63.480(j)(4)(i)(A) 

also requires that a source demonstrate that the malfunction “could not have 

been prevented through careful planning, proper design, or better operation 

and maintenance practices; and did not stem from any activity or event that 

could have been foreseen and avoided, or planned for; ...” That is a vague, 

subjective and potentially impossible criterion. Once an event occurs, you 

may know enough that you “could” have prevented it. In fact, that is the very 

basis for the later requirement to do a root cause analysis – so a facility can 

identify the root cause and plan to prevent recurrences. Even being hit by a 

meteor would fail this test, since one theoretically could have planned for it, 

even if the chance of such an occurrence is infinitesimal. In short, these 

demonstration requirements are so vague and subjective as to make the 

affirmative defense potentially unavailable. 

We believe this paragraph must be limited to showing that the malfunction 

definition criteria were reasonably met and that no expansion beyond that 

definition should be included. Certainly, the record does not support a 

requirement to demonstrate anything more than that the malfunction definition 

was met. Thus, we recommend the following: 

The excess emissions were caused by a sudden, short, infrequent, 

and unavoidable not reasonably preventable failure of air pollution 

control and monitoring equipment, or a process to operate in a normal 

and usual manner; and that the failure was not caused in part by poor 

maintenance or careless operation could not have been prevented 

through careful planning, proper design, or better operation and 

maintenance practices; and did not stem from any activity or event 

that could have been foreseen and avoided, or planned for; and were 

not part of a recurring pattern indicative of inadequate design, 

operation, or maintenance;

3. Proposed § 63.480(j)(4)(i)(B) imposes an unreasonable requirement and 

focuses on the wrong endpoint and should be clarified. 

Proposed § 63.480(j)(4)(i)(B) requires that “Repairs were made as 

expeditiously as possible when the applicable emission limitations were being 

exceeded. Off-shift and overtime labor were used, to the extent practicable to 

make these repairs.” 

The phrase “as expeditiously as possible” is ambiguous and potentially 

impossible to meet. “Possible” is yet another subjective and ill-defined 
51

concept. Furthermore, requiring the “repairs” to be done rapidly is not the 

correct focus because excess emissions may have ceased before repairs are 

complete. The correct focus should be on reducing the excess emissions as 

rapidly as practical, which is addressed in the proposed (C) paragraph. 

Eliminating excess emissions may involve repairs, but may involve adjusting a 

control set point, bypassing a stuck control valve or other operator actions, 

shutting down the equipment or process, or routing the emissions to a an 

alternate control. 

The second sentence, regarding the use of off-shift and overtime labor, is 

based on a misperception that using additional labor somehow indicates 

expediency or efficiency. As mentioned previously, often the excess 

emissions have ceased prior to repair work occurring. Even where repairs are 

the critical path to minimizing emissions, work may be managed adequately by 

rotational shift personnel. In any given case, the enforcement authority may 

choose to question whether appropriate steps were taken to minimize 

emissions. There is no sound reason for the rule to contain a specific but illdefined criterion around overtime labor. 

We recommend § 63.480(j)(4)(i)(B) not be finalized and proposed § 

63.480(j)(4)(i)(C) remain as the basis for demonstrating an appropriate 

response to the malfunction.

4. Proposed § 63.480(j)(4)(i)(D) should be protective of personal injury and 

property damage and EPA should not be suggesting that they are only 

concerned with severe personal injury or property damage. 

Proposed § 63.480(j)(4)(i)(D) states “If the excess emissions resulted from 

a bypass of control equipment or a process, then the bypass was 

unavoidable to prevent loss of life, severe personal injury, or severe 

property damage.” 

The word “severe” should be deleted from this proposed language. This 

language presumes an operator could know the magnitude of injury or 

damage before an incident necessitating a bypass occurs. Any situation that 

presents a risk to people, property, or equipment could be more or less 

“severe” in the end but cannot be precisely foreseen. In addition, there can be 

substantial room for disagreement about what constitutes “severe” property 

damage. And what degree of injury to employees must the bypass avoid in 

order to qualify as avoiding “severe” personal injury? The use of “severe” 

renders this requirement too subjective to be practically enforceable. 

Moreover, potential “severity” is not the proper focus. Bypassing control 

equipment or the process in some cases might be an appropriate exercise of 

good air pollution control practices. For example, a bypass can be the 

appropriate response to an upset, e.g., in order to prevent fouling of pollution 

control equipment media that in turn would result in reduced pollution control 

equipment efficiency or increased pollution control equipment downtime. 
52

5. Proposed § 63.480(j)(4)(i)(E) sets an impossible requirement that invalidates 

the possibility of using the affirmative defense and so should be deleted. 

Proposed § 63.480(j)(4)(i)(E) states “All possible steps were taken to minimize 

the impact of the excess emissions on ambient air quality, the environment, 

and human health.” 

This provision is ambiguous at best and impossible to demonstrate at worst. A 

facility cannot necessarily know in real time what “impacts” or potential impacts 

emissions might have on air quality, the environment, and human health, nor 

can a facility do anything other than minimize emissions to minimize a potential 

impact. In addition, it is impossible to demonstrate that “all possible steps” 

were taken to do anything. Paragraph (C) already requires a source to 

minimize the excess emissions. We do not know what other steps the Agency 

expects or how we could demonstrate that the impacts of those already 

minimized emissions could be further minimized. This paragraph should be 

deleted. 

6. Proposed § 63.480(j)(4)(i)(G) should be revised to reflect the use of current 

recordkeeping technology. 

Proposed § 63.480(j)(4)(i)(G) requires “Your actions in response to the 

excess emissions were documented by properly signed, contemporaneous 

operating logs.” The use of signed logs has declined with the use of various 

forms of electronic recordkeeping. Operators are directed to focus on 

optimizing operations, and responding to malfunctions if necessary, not filling 

out paperwork. Generally, records are maintained of the event characteristics 

(often electronically), the amount of excess emissions and the supporting 

calculation (generally done after the event ends and kept in an engineering 

file), and the steps taken to deal with the event and the excess emissions 

(sometimes electronically, sometimes on paper). 

Thus, we recommend that this requirement be rephrased to require: 

Your actions in response to the excess emissions were documented 

by properly signed, contemporaneous operating logs. Records are 

maintained documenting the malfunction event, including actions 

taken to minimize emissions and the calculation of the amount of 

excess emissions.

7. Proposed § 63.480(j)(4)(i)(H) is duplicative of § 63.483(a)(1), applies more 

broadly than a particular malfunction event, and should be deleted. 

Proposed § 63.480(j)(4)(i)(H) requires “At all times, the facility was operated 

in a manner consistent with good practices for minimizing emissions.” This is 

a general requirement and included in proposed § 63.483(a)(1). Since the 

affirmative defense provisions address emissions during a malfunction, 

where, by definition, there are excess emissions and the affirmative defense 

already requires you to minimize emissions during the malfunction, this 
53

paragraph is redundant and confusing. Furthermore, this paragraph deals 

with the entire facility not just the EPPU or the malfunctioning equipment. It’s 

inclusion in the affirmative defense provisions would suggest that you cannot 

defend yourself for a particular malfunction event if there was some issue 

anywhere else in the facility having nothing to do with the subpart U 

operation. Such a limitation would be unreasonable. 

E. Proposed § 63.480(j)(3) should be made consistent with § 63.480(j)(4)(i)(D) 

and address the safety issues associated with malfunctioning control 

devices. 

Proposed amended § 63.480(j)(3) specifies: 

The owner or operator shall not shut down items of equipment that are 

required or utilized for compliance with this subpart during times when 

emissions (or, where applicable, wastewater streams or residuals) are being 

routed to such items of equipment if the shutdown would contravene 

requirements of this subpart applicable to such items of equipment. 

The existing § 63.480(j)(3) includes an exception to this requirement for 

malfunctions. That exception is proposed for deletion. Proposed § 

63.480(j)(4)(i)(D), on the other hand, indicates that it is excusable to shutdown 

malfunctioning equipment when “the bypass was unavoidable to prevent loss of 

life, severe personal injury, or severe property damage.” While we discuss above 

in our comments on the affirmative defense conditions that we believe any 

personal injury or property damage should qualify for the defense, we believe 

these two paragraphs should be made consistent and thus the bypass exception 

for malfunctions in the current § 63.480(j)(3) should be maintained. 

F. Front-end control device maintenance should be addressed. 

For continuous front-end process vents in Butyl, Halobutyl, and EPR units, the 

proposed halogen control requirements will require use of a thermal 

oxidizer/halogen scrubber in place of the flare and other combustion devices 

currently in use to meet the organic HAP requirements of the current rule. 

Thermal oxidizer/halogen scrubber systems are likely to have lower service factors 

than the process unit, flare or other combustion device, because of their increased 

susceptibility to halogen corrosion and to plugging problems. Since the flare would 

comply with the organic HAP removal requirement and the thermal 

oxidizer/halogen scrubber is a beyond the floor step, an allowance for some 

thermal oxidizer/halogen scrubber maintenance is allowable as long as it is 

reasonable and considered in the beyond-the-floor evaluation. We, therefore 

suggest EPA allow up to 240 hours per year of thermal oxidizer/halogen scrubber 

outage, as long as the front-end process vents are routed to a flare or other 

combustion device during that outage. This represents a maximum decrease in 

post control HCl emissions from 125.6 Tons/year to 121.8 Tons/year for the Butyl 

and Halobutyl subcategories and EPR category combined and would save 

potentially significant production losses, costs and emissions by avoiding unit 

shutdowns to allow maintenance of these devices. 
54

IX. Other Comments and Edits 

A. The proposed controls are inconsistent with the EPA Administrator’s key 

principles which include getting meaningful results with cost-effective 

controls. 

On the 40th anniversary of the Clean Air Act (September 14, 2010) Lisa Jackson 

outlined five principles to address concerns about overly expensive or burdensome 

rules. The principles included: promoting energy efficiency and new technologies; 

using a multipollutant approach to rules; setting achievable standards with 

flexibility to meet them; seeking input from all stakeholders -- the public, industry, 

states and others -- on rules; and setting cost-effective standards that get 

meaningful results. Her specific remarks included:

Finally, we will set the standards that make the most sense – focusing on 

getting the most meaningful results through the most cost-effective 

measures (emphasis added). The Clean Air Act does not compel regulations 

for all industry categories, and we want to ensure that we move forward 

without burdening small businesses, non-profits and other entities that don’t 

account for significant amounts of pollution in our skies. 

Our goal is to use the tools in Clean Air Act to provide flexibility for everyone, 

to work in sync with market principles and to encourage investment in new 

technologies that provide cost-effective and efficient methods for lowering 

pollution in the air we breathe. As Administrator and as an American 

consumer, I know we must be smart in the strategies we employ. Industry 

needs clarity and certainty to make the best investments. They are the key to 

the innovation that helps us reduce pollution, protect our health and preserve 

our environment. 

The proposed controls for the Butyl Rubber and EPR source categories are 

inconsistent with the stated principles of the Administrator as they are not costeffective, add costs that have no substantive environmental benefit, and reduce 

competitiveness of U.S. manufacturing. Furthermore, the rule would result in the 

diversion of investment capital that could be used for more productive purposes 

(e.g. energy efficiency, process improvements) thereby supporting economic 

growth and cost-competitiveness. Companies have capital budgets that 

necessitate difficult choices; capital funds are not unlimited. 

B. Since there is no deadline for finalizing any rule related to the Butyl Rubber 

and EPR source categories, EPA should take the appropriate amount of time 

to thoroughly review the comments submitted and re-assess their beyondthe-floor cost-effectiveness determination. 

There is no legal deadline to finalize the rule for four source categories within the 

Group I Polymers and Resins category of sources, including Butyl Rubber and 

Ethylene Propylene Rubber. This is recognized in the revised consent decree that 

resolves a lawsuit filed by the Sierra Club in the United States District Court for the 
55

Northern District of California (Sierra Club v. Jackson, No. 09-cv-00152 SBA). The 

revised consent decree was filed September 27, 2010 and now states: 

On December 16, 2008, EPA published a final determination under sections 

112(d)(6) and 112(f)(2) for the following four Group I Polymers and Resins 

categories: Polysulfide Rubber Production; Ethylene Propylene Rubber 

Production; Butyl Rubber Production; and Neoprene Production. See 73 Fed. 

Reg. 76,220. The allegations in plaintiff’s Complaint address only the five 

Group I Polymers and Resins categories not covered by the December 2008 

action. [Sierra Club v. Jackson, No. 09-cv-00152 SBA, page 3, footnote 2]

Before the consent decree was modified EPA had a final rule date of June 30, 

2011. Based on the revised consent decree, EPA should establish a rulemaking 

schedule for the four source categories referenced above that is more appropriate 

for a rule with such significant issues. Typically, EPA requires about one year from 

the date of a proposed rule to the date of a final rule. This time period allows for a 

thorough review of comments submitted and the revision of the proposed rule as 

appropriate. 

C. Provisions are needed to address maintenance of surge control vessels 

controlled with non-water condensers. 

Condensers are commonly used to control storage vessels and surge control 

vessel emissions in elastomer operations, because they recover the controlled 

material and are very cost-effective due to the availability of high-level refrigeration 

(e.g., propane refrigeration). However, these controls become ineffective when the 

refrigeration system must be shut down for maintenance. This has not been an 

issue under subpart U as a result of the shutdown exemption and will not be a 

significant issue for storage vessels with removal of the shutdown exemption 

because of the storage vessel planned routine maintenance provisions. 

However, the planned routine maintenance provisions in the storage vessel 

provisions do not apply to surge control vessels. Thus, sources will have to install 

combustion or other controls in place of the condenser systems for surge control 

vessels controlled in this manner. This change will be costly and is not discussed 

in the record. Changing surge control vessel controls will result in loss of the vent 

material rather than its recovery and will generate combustion emissions, including 

NOx and greenhouse gas emissions. Furthermore, it cannot be accomplished by 

the promulgation date of the rule, which is the apparent effective date for the loss 

of the shutdown exemption. The emissions involved are relatively small and are 

currently emitted and thus it would not be justified to control them even if time 

permitted. Thus, we request that, as has been done in other rules (e.g., the MON 

rule) that subpart U allow use of the storage vessel control provisions for surge 

control vessels. We suggest the following amendment to § 63.502(a) to 

accomplish this revision. 

 Equipment leak provisions. The owner or operator of each affected 

source, shall comply with the requirements of subpart H of this part, with 

the exceptions noted in paragraphs (b) through (m) of this section. Surge 
56

control vessels required to be controlled by subpart H may, alternatively,

comply with the Group 1 storage vessel provisions specified in § 63.484.

At our Baytown Butyl Rubber Unit, the refrigerated condensers are followed by a 

dual bed carbon adsorption system in order to comply with State requirements. 

However, the carbon system does not achieve 95% removal if the condenser is out 

of service and so these surge control vessels cannot meet the normal NESHAP 

requirements (40 CFR 63.172) when the refrigeration system is shutdown. The 

Agency did not consider this situation in evaluating whether to extend the normal 

subpart U emission limits to startup and shutdown periods. In this case, the 

normal limits are met for a time, but the carbon system can sometimes have 

breakthrough if the primary bed has become saturated because the secondary bed 

can become saturated before the primary bed can be changed, since it can take up 

to 24 hours to change a carbon bed. If the Agency does not address startups and 

shutdowns in general, it should address this situation in particular by allowing up to 

24 hours to change or replace a saturated carbon bed, where carbon beds are 

used as controls during startup and shutdown periods. Addressing this situation is 

appropriate because carbon adsorption is a typical temporary control that can be 

used to control startup and shutdown emissions when the primary control must be 

shutdown. 

D. The back-end emission limits and emission calculations for the Butyl and 

Halobutyl units should be based on total elastomer production. 

Proposed § 63.494(a)(4)(i) establishes an emission limit based on Butyl Rubber 

production and § 63.494(a)(4)(iii) establishes an emission limit based on Halobutyl 

Rubber production. However, the Baytown unit, for example, has flexible 

operations that produce Butyl Rubber some of the time and Halobutyl Rubber at 

other times. Thus, the divisor for the each of these subcategories should be total 

rubber production, not just production of one type of rubber. The associated 

compliance provisions in proposed § 63.495(g)(4) already handle this concern by 

specifying the divisor as “total elastomer produced.” As we discussed in Section 

III, we also believe it needs to be clarified that this is the mass of elastomer leaving 

the stripper, not finished rubber production. 

E. The first example at the end of the current § 63.480(j)(1) is useful and should 

not be deleted and the missing “the” in the proposed language should be 

added. 

§ 63.480(j)(1) is proposed to be modified as follows: 

 The emission limitations set forth in this subpart and the emission 

limitations referred to in this subpart shall apply at all times except during 

periods of non-operation of the affected source (or specific portion thereof) 

resulting in cessation of the emissions to which this subpart applies. The 

emission limitations of this subpart and the emission limitations referred to 

in this subpart shall not apply during periods of start-up, shutdown, or 

malfunction, except as provided in paragraphs (j)(3) and (j)(4) of this 

section. However, if a period of startup, shutdown, malfunction or non-
57

operation of one portion of an affected source does not affect the ability of 

a particular emission point to comply with the emission limitations to which 

it is subject, then that emission point shall still be required to comply with 

the applicable emission limitations of this subpart during the start-up, 

shutdown, malfunction, or period of non-operation. For example, if there is 

an overpressure in the reactor area, a storage vessel that is part of the 

affected source would still be required to be controlled in accordance with 

the emission limitations in § 63.484. Similarly, the degassing of a storage 

vessel would not affect the ability of a batch front-end process vent to meet 

the emission limitations of §§ 63.486 through 63.492.

 The word “the” should not be deleted in the phrase “comply with the applicable 

emission limitations of this subpart during the start-up, shutdown, malfunction, 

or period of non-operation.” Additionally, the first example in the last two 

sentences of the existing language are helpful to understanding the meaning 

of this paragraph and we suggest they be retained rather than deleted. 

Removing the startup, shutdown and malfunction exemptions has no impact 

on that example. 

F. The introductory sentence of § 63.505(g) needs to be modified to limit the 

applicability of that section to match the rest of the changes. 

Existing § 63.505(g) states: 

Parameter monitoring excursion definitions. (1) With respect to storage 

vessels (where the applicable monitoring plan specifies continuous 

monitoring), continuous front-end process vents, aggregate batch vent 

streams, back-end process operations complying through the use of 

control or recovery devices, and process wastewater streams, an 

excursion means any of the three cases listed in paragraphs (g)(1)(i) 

through (g)(1)(iii) of this section. 

However, only the back-end process operations currently regulated by subpart 

U have monitoring requirements and are subject to the excursion definitions in 

(g). Excursions for the proposed new back-end requirements for Butyl and 

Halobutyl subcategories are defined in proposed § 63.505(j) and not in this 

paragraph (g). Thus, as has been done elsewhere, the current requirement 

needs to be limited to back-end operations subject to § 63.494(a)(1) through 

(3). 

 We suggest § 63.505(g) be revised as follows: 

Parameter monitoring excursion definitions. (1) With respect to storage 

vessels (where the applicable monitoring plan specifies continuous 

monitoring), continuous front-end process vents, aggregate batch vent 

streams, back-end process operations complying with § 63.494(a)(1) 

through (3) through the use of control or recovery devices, and process 

wastewater streams, an excursion means any of the three cases listed in 

paragraphs (g)(1)(i) through (g)(1)(iii) of this section. 
58

G. EPA’s preamble claim that dioxins and furans are formed when chlorinated 

hydrocarbons are burned in a flare and, presumptively, that their combustion 

in a thermal oxidizer reduces the generation of these compounds, is 

unsupported and should be rescinded in the final rule preamble. 

In Section V.B.6.b, of the proposal preamble, the Agency claims, relative to 

combusting chlorinated hydrocarbons in a flare, that: 

When chlorinated organics are burned in a flare, there are variations in the 

combustion which likely results in the formation of combustion by-products. 

These combustion by-products could include trace chlorinated compounds 

such as dioxins and furans. [75 Fed. Reg. 65108] 

There is no data in the record to support this supposition. Furthermore, there is no 

data to suggest that, even if this were the case, less dioxin or furan would be 

formed in the thermal oxidizer/scrubber system the Agency proposed to require 

instead of the flare. The basis for the beyond-the-floor proposal to control 

halogens in Group 1 continuous front-end process vents is HCl generation and 

there is no basis for suggesting that there is any benefit relative to dioxin/furans 

that results from the proposal. This preamble statement should be withdrawn in 

the final rule preamble. 

H. Other Edits 

1. The introductory paragraph to § 63.498(a) should reference (a)(1) through 

(a)(4), not (a)(1) through (a)(3). 

2. The reference to Table 8 in the existing § 63.493 is proposed for deletion, but 

should be kept. Otherwise Table 8 should be deleted, since it is not otherwise 

referenced. 

X. Residual Risk and Technology Review: Butyl Rubber and EPR Source 

Categories 

A. ExxonMobil supports EPA’s position that it was not necessary to revisit the 

residual risk review as part of this rulemaking. 

In the proposed rule EPA notes, for the Butyl Rubber and EPR source categories, 

that these source categories were previously determined to be low-risk (maximum 

lifetime cancer risk less than 1-in-1 million). Consequently EPA does not believe it 

necessary to conduct a facility-wide or demographic risk analysis. EPA therefore 

did not address the residual risk review in this rulemaking. 

CAA § 112(f)(2) requires EPA to promulgate standards for each category or 

subcategory of sources: 

if promulgation of such standards is required in order to provide an ample 

margin of safety to protect public health... or to prevent, taking into 
59

consideration costs, energy, safety and other relevant factors, an adverse 

environmental effect... If standards promulgated pursuant to subsection (d) 

and applicable to a category or subcategory of sources emitting a pollutant (or 

pollutants) classified as a known, probable, or possible human carcinogen do 

not reduce lifetime excess cancer risks to the individual most exposed to 

emissions from a source in the category or subcategory to less than one-in-one 

million, the Administrator shall promulgate standards under this subsection for 

such source category. 

In the 2007 proposed residual risk rule for source categories that include Butyl 

Rubber and EPR EPA notes: 

... we estimate that the residual risk remaining from HAP emission from these 

eight source categories affected by today’s proposal do not pose cancer risks 

equal to or greater than 1-in-1 million to the individual most exposed, do not 

result in meaningful rates of cancer incidence, and do not result in a concern 

regarding either chronic or acute noncancer health effects for the individual 

most exposed. No chronic inhalation human health thresholds were exceeded 

at ecological receptors for any of the eight source categories; therefore, we 

believe there is low potential for adverse environmental effects due to direct 

airborne exposures. We also believe that there is no potential for an adverse 

effect on threatened or endangered species or on their critical habitat within the 

meaning of 50 CFR 402.13(a) because our screening analyses indicate no 

potential for any adverse ecological impacts. [72 Fed. Reg. 70552-3] 

As EPA noted in the proposed rule, none of the hazardous air pollutants in the 

Butyl Rubber and EPR source categories are carcinogenic hence there is no 

cancer risk. In addition, the maximum Hazard Index (HI) for any facility in the 

source categories impacting ExxonMobil is as follows: 

1. Butyl Rubber: Maximum HI = 0.2 

2. Ethylene Propylene Rubber: Maximum HI = 0.5 

Based on the risk assessment results EPA concluded that no further regulation 

was required because the existing MACT standards protect public health with an 

ample margin of safety and prevent an adverse environmental effect: 

EPA is not required to promulgate standards for a source category under 

section 112(f) if public health is protected with an ample margin of safety and 

adverse environmental effects are prevented.... In making this conclusion we 

determined that the source categories addressed in today’s proposal that emit 

one or more HAP which are known or potential carcinogens pose cancer risks 

less than or equal to 1-in-1 million to the individual most exposed. In addition, 

we also determined that emissions from these source categories result in 

chronic noncancer target organ-specific HI less than or equal to 1 for the 

individual most exposed, are unlikely to result in health effects under acute 

scenarios and are not anticipated to pose any significant and widespread 

adverse environmental effects. [72 Fed. Reg. 70555] 
60

 

In the 2008 final rule EPA stated that the HAP emissions: 

... do not pose cancer risks equal to or greater than 1-in-1 million to the 

individual most exposed, do not result in meaningful rates of cancer incidence, 

and do not result in a concern regarding either chronic or acute noncancer 

health effects for the individual most exposed. In addition, no chronic inhalation 

human health thresholds were exceeded at environmental receptors... there is 

low potential for adverse environmental effects... there is no potential for an 

adverse effect on threatened or endangered species. [73 Fed. Reg. 76225] 

ExxonMobil supports EPA’s conclusion that under the CAA no further regulation is 

required due to the very low risk associated with the ExxonMobil and other facilities 

in the Butyl Rubber and EPR source categories. The post-MACT (implementation 

of Maximum Achievable Control Technology standards) emission risks addressed 

by EPA from these sources fall well within the acceptable risk range established by 

the decision framework codified in § 112 (Benzene NESHAP). 

B. ExxonMobil supports EPA’s position that it was not necessary to revisit the 

technology review as part of this rulemaking and that no additional controls 

are required based on the technology review. 

In the 2007 proposed rule EPA concluded: 

... there have been no significant developments in practices, processes, or 

control technologies since promulgation of the MACT standards. Because 

there have been no such significant developments and because public health is 

protected with an ample margin of safety, we conclude that no further revisions 

to the standards affected by today’s proposal are needed under section 

112(d)(6) of the CAA. [72 Fed. Reg. 70555] 

In conducting the technology review EPA relied on the technology review 

conducted for the Hazardous Organic NESHAP (HON), which did not identify any 

significant developments in practices, processes, or control technologies since 

promulgation of the original HON standards in 1994. This is an appropriate 

analysis since control devices applicable to the source categories included in this 

proposed rule are similar to the ones impacting HON facilities. In addition, EPA 

indicated a “development” for purposes of the technology review would be based 

on: 

1. Any add-on control technology or other equipment, and any work practice or 

operational procedure, and any process change or pollution prevention 

alternative that could be broadly applied that was not identified and considered 

during MACT development. 

 2. Any improvements in add-on control technology or other equipment (that was 

identified and considered during MACT development) that could result in 

significant additional emission reduction. 
61

EPA also stated: 

While we agree that no further controls are required under the technology 

review, our view is that for facilities that have risks below the level that 

triggers regulation (e.g., 1-in-1-million cancer risk) a technology review is not 

needed. In these cases there is no likelihood of additional meaningful risk 

reductions. Conducting a technology review is suggesting that reducing risk 

below 1-in-1 million should continue to be a policy objective even though 

Congress established this risk level as the level for which source categories 

are eligible for delisting from the program. Continued focus on these low risk 

sources is contrary to the direct language of the Act, creates significant 

regulatory uncertainty and would simply act to waste both public and private 

sector resources. [Memo dated December 12, 2007; “Developments in 

Practices, Processes, and Control Technologies for RTR Phase II, Group 1 

Source Categories...;” in the EPA docket] 

ExxonMobil supports EPA’s conclusion that no additional controls are required 

based on the §112(d)(6) technology review. 

C. EPA should delist the Butyl and EPR source categories due to low risk. 

1. EPA has the legal authority to delist source categories. 

 Under CAA § 112(c)(9): 

(B) The Administrator may delete any source category from the list under 

this subsection, on petition of any person or on the Administrator’s own 

motion, whenever the Administrator makes the following determination or 

determinations, as applicable: 

(i) In the case of hazardous air pollutants emitted by sources in the 

category that may result in cancer in humans, a determination that no 

source in the category (or group of sources in the case of area sources) 

emits such hazardous air pollutant in quantities which may cause a lifetime 

risk of cancer greater than one in one million to the individual in the 

population who is most exposed to emissions of such pollutants from the 

source (or group of sources in the case of area sources). 

(ii) In the case of hazardous air pollutants that may result in adverse health 

effects in humans other than cancer or adverse environmental effects, a 

determination that emissions from no source in the category or subcategory 

concerned (or group of sources in the case of area sources) exceed a level 

which is adequate to protect public health with an ample margin of safety 

and no adverse environmental effect will result from emissions from any 

source (or from a group of sources in the case of area sources). 

The Administrator shall grant or deny a petition under this paragraph within 

1 year after the petition is filed. 
62

An important point to note is that the Administrator does not require a formal 

petition to delist a source category. EPA, on their own, can initiate the 

delisting based on the data available. 

2. EPA has demonstrated low risk for the Butyl Rubber and EPR source 

categories and should now take the steps to delist these source 

categories from the air toxics regulations. 

EPA ran risk models for the sources in the Butyl Rubber and EPR source 

categories for the 2007 proposed rulemaking and, based on the data provided 

in 2010, found no reason to rerun the models. As noted above: 

(i) None of the HAPs in the Butyl Rubber and EPR source categories are 

carcinogenic hence there is no cancer risk. 

(ii) For Butyl Rubber the maximum HI was = 0.2. 

(iii) For Ethylene Propylene Rubber the maximum HI was = 0.5. 

Based on the extensive analysis for the Butyl Rubber and EPR source 

categories, EPA should initiate a process to delist these two source categories. 

 

XI. EPA Policy on Residual Risk and Technology Reviews 

 A. Continuing implementation of residual risk and technology reviews should 

be consistent with the HON Court decision. 

The June 6, 2008 “HON” court decision (No. 07-1053, NRDC and LEAN v. EPA) 

supported several key EPA policy decisions. The court case related to challenges 

to the final residual risk and technology reviews for the Hazardous Organic 

National Emission Standards for Hazardous Air Pollutants (HON), finalized 

December 21, 2006. 71 Fed. Reg. 76603. 

The court decision addressed EPA decisions under both the residual risk (CAA § 

112(f)(2)) and technology review (CAA § 112 (d)(6)) programs. Key elements of 

the court decision, from a policy perspective are summarized below: 

1. EPA has the discretion to determine that a maximum individual cancer 

risk level of approximately 100-in-1 million for a source category is 

acceptable; EPA is not obligated to revise industry standards to reduce 

lifetime excess cancer risk to one-in-one-million. 

From the court decision: 

The cited item in the Federal Register is EPA’s emission standard for 

benzene, which is a carcinogenic hazardous air pollutant. In the Benzene 

rulemaking, EPA set forth its interpretation of “ample margin of safety,” as 

that term was used in the 1970 version of the Clean Air Act. It said that the 

“ample margin” was met if as many people as possible faced excess lifetime 
63

cancer risks no greater than one-in-one million, and that no person faced a 

risk greater than 100-in-one million (one-in-ten thousand). 54 Fed. Reg. at 

38,044-45. In other words, the Benzene standard established a maximum 

excess risk of 100-in-one million, while adopting the one-in-one million 

standard as an aspirational goal. This standard, incorporated into the 

amended version of the Clean Air Act, undermines petitioners’ assertion that 

EPA must reduce residual risks to one-in-one million for all sources that 

emit carcinogenic hazardous air pollutants. [NRDC v. EPA,529 F.3d 1077, 

1082 (D.C. Cir. 2008)] 

In the Benzene NESHAP, EPA stated an overall objective as follows: 

... in protecting public health with an ample margin of safety, we strive to 

provide maximum feasible protection against risks to health from hazardous 

air pollutants by (1) protecting the greatest number of persons possible to 

an individual lifetime risk level no higher than approximately 1-in-1-million; 

and (2) limiting to no higher than approximately 1-in-10 thousand (i.e., 100-

in-1 million ) the estimated risk that a person living near a facility would have 

if he or she were exposed to the maximum pollutant concentrations for 70 

years. [75 Fed. Reg. 65072] 

2. Cost is to be considered when determining the “ample margin of safety”, 

consistent with the Benzene NESHAP. 

Finally, petitioners argue that EPA unlawfully considered 

cost while setting the “ample margin of safety” in the residual 

risk standards. Petitioners are correct that the Supreme Court 

has “refused to find implicit in ambiguous sections of the [Clean 

Air Act] an authorization to consider costs that has elsewhere, 

and so often, been expressly granted.” Whitman v. Am. Trucking 

Ass’n, 531 U.S. 457, 467 (2001). In this case, however, we 

believe the clear statement rule has been satisfied. As explained 

above, subsection 112(f)(2)(B) expressly incorporates EPA’s 

interpretation of the Clean Air Act from the Benzene standard, 

complete with a citation to the Federal Register. In that 

rulemaking, EPA set its standard for benzene “at a level that 

provides ‘an ample margin of safety’ in consideration of all 

health information . . . as well as other relevant factors including 

costs and economic impacts, technological feasibility, and other 

factors relevant to each particular decision.” 54 Fed. Reg. at 

38,045 (emphasis added). EPA considered cost in Benzene, and 

subsection 112(f)(2)(B) makes clear that nothing in the amended 

version of the Clean Air Act shall “affect[]” the agency’s interpretation of the 

statute from that rulemaking. [NRDC,529 F.3d at 1083] 

3. The technology review does not require a recalculation of the MACT floor 

standards. 
64

For the technology review, EPA has adopted the position that they would 

evaluate developments in practices, processes, and control technologies and 

then revise a standard as necessary. A recalculation of the floor is not 

required. Recalculating the floor every 8 years would lead to a ratcheting down 

of the standards, a methodology not indicated in the CAA and one that would 

lead to high costs and potentially impractical standards for many manufacturers 

with little or no health benefit. 

It is argued that EPA was obliged to completely recalculate the maximum 

achievable control technology – in other words, to start from scratch. We do 

not think the words “review, and revise as necessary” can be construed 

reasonably as imposing any such obligation. Even if the statute did impose 

such an obligation, petitioners have not identified any post-1994 

technological innovations that EPA has overlooked. [Id. at 1084] 

B. The Residual Risk and Technology Reviews should be concurrent. 

The CAA requires, after promulgation of each MACT, both a residual risk (within 8 

years) analysis and a technology review (no less often than every 8 years). Since 

these assessments apply to the same sources, including individual emission 

sources, and are interrelated, it is an efficient use of Agency and industry 

resources to conduct these reviews at the same time. This also avoids the 

potential for inconsistency in separate rulemakings. In addition, the results of the 

residual risk assessment should be used to inform the technology review 

determination. We support EPA’s efforts to conduct the reviews concurrently as 

they have done for the source categories evaluated to-date, and we encourage 

the Agency, despite the pressures of time and litigation, to continue this approach. 

C. Risk assessments should be based on source category actual emissions. 

The foundation for any regulatory decision-making should be a sound database 

that reflects actual emissions and appropriate/realistic modeling inputs and 

assumptions. It is appropriate to use actual emissions data in determining risk. 

The Agency’s risk assessments are inherently conservative. To the extent real 

data is used, the risk assessment becomes more realistic. Potential emissions 

overstate emissions and risk because facilities do not operate at the level of their 

potential emissions (oftentimes the permit limit) in order to maintain a compliance 

margin. 

It is also appropriate to focus the risk assessment on the source category to be 

regulated. If there are other sources (e.g., mobile sources, area sources) that are 

contributing to or driving the risk, these sources should be evaluated under 

separate rulemaking since further controls on P&RI sources do not address any 

issues with these other sources. In addition, the CAA is quite clear in § 

112(f)(2)(A): 

[T]he Administrator shall, within 8 years after promulgation of standards for 

each category or subcategory of sources pursuant to Subsection (d), 

promulgate standards for such category or subcategory if promulgation of such 
65

standards is required in order to provide an ample margin of safety to protect 

public health in accordance with this section... 

D. Risk should be evaluated at the centroid of census blocks. 

It is also appropriate to use the centroid of census blocks in determining maximum 

individual risk. This is where people live and may potentially be impacted. 

Modeling to a fenceline is inappropriate in a risk assessment because people do 

not live on the fenceline and this approach overstates risk. This approach is 

consistent with EPA’s position stated in the final decision on the residual risk rule 

for Gasoline Distribution Facilities. 

In a national-scale assessment of lifetime inhalation exposures and health risks 

from a category of facilities, it is appropriate to identify exposure locations 

where an individual may reasonably be expected to spend a majority of his or 

her lifetime. Further, it is appropriate to use census block information on where 

people actually reside, rather than points on a fenceline, to locate the 

estimation of exposures and risks to individuals living near such facilities. [71 

Fed. Reg. 17354] 

E. EPA should not expand the health information metrics beyond those already 

evaluated; the three planned added measures do not provide needed 

information on the cancer and non-cancer risk of the regulated source 

category. 

In the proposed rule preamble EPA outlines the planned approach to future 

residual risk rule reviews. The overall approach is outlined in the Benzene 

NESHAP and is a two-step process. The first step is the determination of 

acceptable risk; the second step provides for an ample margin of safety while 

evaluating other relevant factors including costs, economic impacts and 

technological feasibility. 

In the past the Agency has looked at several human health risk metrics associated 

with emissions from the category, including: 

1. The MIR (maximum individual risk); 

2. The numbers of persons in various risk ranges; 

3. Cancer incidence; 

4. Maximum non-cancer hazard index (HI); and 

5. Maximum acute non-cancer hazard. 

As part of the analysis EPA also considered source categories under review that 

are located near each other, assessed impact of maximum emissions allowed in 

addition to actual emissions, and considered risk estimating uncertainties. 
66

In the revised future approach to residual risk rules EPA is also planning to 

consider additional measures of health information, including: 

1. Estimates of “total facility” cancer and non-cancer risk; 

2. Demographic analyses (distribution of risks across different social, 

demographic, and economic groups within the populations near the facilities 

where source categories are located); and 

3. Additional estimates of the risks from emissions allowed by the MACT 

standard (i.e. maximum allowable emissions or permit limits). 

A concern with this expansion of health measures is that they dilute the more 

important health measures already in place which more directly, although 

conservatively, assess the risk from the regulated source category. Additional 

concerns with the added measures include: 

1. It is not clear how these additional measures will actually be used to modify a 

standard. For example, what is the legal basis for these measures and what 

criteria will be applied in assessing these measures and modifying an 

emission standard? 

2. Using “allowable emissions” overstates risk, as EPA has acknowledged. Use 

of actual emissions provides a more realistic estimate of risk. Facilities always 

strive to maintain a compliance margin, which is the margin between allowable 

and actual emissions, to ensure ongoing compliance. If actual risk is 

acceptable, would EPA, in the absence of data suggesting there is a problem, 

really require additional controls just because maximum or allowable 

emissions could, theoretically, result in higher emissions? 

In summary, EPA should not expand the health information metrics beyond those 

already evaluated. The three planned added measures do not provide needed 

information on the cancer and non-cancer risk of the regulated source category. 

F. In calculating cost-effectiveness in residual risk decisions, EPA should 

evaluate cost on a risk reduction basis. 

EPA traditionally evaluates cost-effectiveness in terms of cost per ton of pollutant 

reduced. This is certainly an appropriate approach in evaluating MACT beyondthe-floor determinations. However, in a risk-driven rule EPA should evaluate cost 

on a cost per unit of risk reduction basis. This approach ties better to the objective 

of the residual risk program. For example, for a carcinogenic HAP, EPA should 

evaluate cost-effectiveness by determining the cost per cancer incidence reduced. 

G. In addition to the health risk metrics already established, EPA should include 

central tendency or most expected risk assessments to better communicate 

the conservative nature of EPA risk assessments. 

 
67

EPA’s risk assessments are inherently very conservative for a number of reasons, 

including: 

1. Unit risk estimates for cancer used by the Agency are upper bound numbers, 

hence they overstate the true risks. 

 

2. Exposure assumptions are conservative; they include the assumption that an 

individual is exposed to the highest concentration for 70 years. The reality is 

that the movements of individuals results in a typical exposure period of 

significantly less than 70 years. As EPA has noted: 

We acknowledge that the use of upper bound URE and 70-year exposure 

duration are sources of uncertainty in our analyses that tend to 

overestimate risk. [73 Fed. Reg. 76228] 

To better communicate the conservative nature, and therefore the health protective 

aspect, of residual risk rules EPA should develop most expected (i.e. 50% 

probability of occurrence) or central tendency estimates. 

H. In the future, when EPA finalizes a residual risk rule with controls and work 

practices, the rule should not be applicable to low-risk sources. 

In the March 1999 “Residual Risk Report to Congress,” EPA indicated that after 

the implementation of the MACT technology standards “EPA will then evaluate the 

remaining risk and consider ample margin of safety as discussed below. In those 

cases where it is determined to be necessary, EPA will use CAA Section 112(f)(2) 

residual risk authority to set national standards but focus the applicability of 

standards only on those portions of the source category.” 

A low-risk exclusion should be included in future rules based on a site-specific 

determination similar to applicability determinations for other rules (e.g. NSPS, 

MACT). Anything beyond this is inconsistent with the recognition that many 

sources are low-risk and don’t require additional regulation. 

I. The applicability determination approach for low-risk sources should not 

establish on-going permitting and reporting requirements when the rule is 

not applicable. 

Our recommended approach for low-risk determinations in future rules is 

consistent with the approach taken in other air rules, where a facility determines 

initial applicability and later reviews applicability through a management-of-change 

process related to capital investments and operational changes. For example, in 

NSPS rules certain site changes could trigger applicability, but the initial permit 

would only indicate that a certain NSPS rule was not applicable and would not 

include additional permit terms to demonstrate “non-applicability” such as requiring 

additional emission limits at the “modification” threshold level. 

EPA does not currently require an onerous process with significant on-going 

requirements for “non-applicability” determinations for other federal rules, and 
68

should not take this approach under a residual risk program. Any demonstration 

criteria to determine that a site is low risk should not be more onerous or costly 

than complying with the control and work practice standards. 

J. The applicability determination for low risk sources should include elements 

that streamline the process while recognizing the low-risk nature of the 

sources. 

Some of the key elements of a low-risk applicability determination, consistent with 

the low or negligible risk associated with facilities not requiring further controls, 

include: 

1. Facilities can use any scientifically accepted, peer-reviewed risk assessment 

methodology. 

2. Set the rule applicability threshold at a risk level that reflects the ample margin 

of safety that results from the proposed controls and work practice standards, 

consistent with the findings of the risk assessments for the source category. 

An alternate, very conservative approach is to base applicability on a threshold 

level that defines low-risk sources as having a cancer risk less than or equal 

to 1-in-1 million and a hazard index less than or equal to 1. Since EPA has 

already decided not to regulate source categories with risks higher than 1-in-1 

million, and the Benzene NESHAP decision framework supports evaluating 

factors that will result in acceptable risk levels above 1-in-1 million, it would be 

within the Agency’s discretion to establish an applicability threshold at a level 

above 1-in-1 million. 

3. Include a notation in a Title V application (or permit) that the residual risk 

standards are not applicable to the specific source. No other permit terms are 

appropriate (since the rule isn’t applicable). Title V provides an ongoing 

compliance certification obligation for sources and Responsible Officials. 

4. Applicability determinations should not require a regulatory approval process. 

Applicability determinations would be available for review by regulatory 

authorities. In the HON proposal, EPA requested comment on the possible 

means for “approving” such demonstrations (e.g., by EPA affirmative review, 

by the State permitting authority, by EPA audit, by third-party, or by selfcertification plus EPA audit). The suggestion that some type of approval is 

necessary for non-applicability determinations for low-risk sources would set 

up a burdensome, unwarranted process. Needless to say, States will be 

concerned about a possible ongoing obligation to approve these 

determinations. Setting up a process of this nature would discourage the lowrisk applicability approach and is inconsistent with the Agency’s past stated 

objective of not regulating low-risk sources. 

5. Facilities would continue to have the on-going obligation, similar to the 

obligation for all federal/state/local air rules, to reassess applicability when 

facility changes are judged to potentially impact rule applicability. 
69

6. Applicability reassessments should be limited to source changes (within the 

control of the company) and changes that go through a formal rulemaking 

process. This is the approach that has been taken with other air rules. Lowrisk sources should not have to review applicability due to changes outside the 

control of the facility. Changes to health benchmarks, EPA risk assessment 

procedures, improvements and changes in dispersion models, and changes in 

human population and census track data should not automatically trigger a 

source obligation to reassess applicability. Issues related to these type 

changes are broader than those of individual sources. 

 

7. The analysis and modeling should be consistent with the health concerns in 

the source category. For example, if the concern is chronic impacts then the 

modeling should be based on annual emissions and no hourly modeling for 

acute effects should be required. 

8. If EPA determines for a source category that there are no adverse 

environmental risks, then there should be no requirements on individual 

facilities to demonstrate no adverse environmental risk. 

9. The applicability determination should be completed before the first major 

compliance date of the rule. 

 

K. Application of CAA § 112(d)(6) should incorporate the framework of § 

112(f)(2). 

CAA § 112(d)(6) requires the Agency to review, and revise emission standards as 

necessary, taking into account developments in practices, processes and control 

technologies. EPA should base any review and revision under § 112(d)(6) through 

the lens and the structure of the § 112(f) rulemaking framework: 

We also believe that the periodic review should be of whatever Section 112 

standard applies to the relevant source category, regardless of whether the 

original Section 112(d) and/ or 112(h) NESHAP has, or has not, been revised 

pursuant to Section 112(f)(2). We recognize that one could read the Section 

112(f)(2) language to authorize EPA's setting a standard under Subsection 

(f)(2) separate from the NESHAP standard set under Subsections (d) and/or 

(h). Following this reading, one might argue that any review under (d)(6) 

should be only of the (d)(2), (d)(4), or (d)(5) NESHAP standard, as applicable. 

It is our position, however, that the better reading of (f)(2) allows EPA to revise 

the relevant Subsection (d) standard if the agency determines residual risk so 

justifies under (f)(2); indeed, our practice has been to follow this approach. 

[Coke Ovens; 70 Fed. Reg. 19993] 

This approach would require the Administrator to weigh the potential for future risk 

reduction under § 112(d)(6) against the cost of that reduction in the same manner 

as set forth in the second step of the 1989 Benzene NESHAP rule. Under the 

1989 Benzene NESHAP rule, the primary objective of § 112(f) is to assure that 

emissions are controlled to a level that can be considered “acceptable” or “safe.” 
70

Reviews that focus solely on cost-per-ton formulations that do not consider the risk 

reduction potential of controls could result in the imposition of technology controls 

that yield very little if any reduction in risk. Since Congress expressly rejected this 

approach in its codification of the decision framework in the 1989 Benzene 

NESHAP rule, it is difficult to believe that the EPA should adopt this approach in 

conducting reviews under § 112(d)(6). In the Benzene NESHAP rule codified by 

Congress, EPA assessed the economic cost and feasibility of requiring additional 

controls for five source categories. EPA considered and then rejected more 

expensive control options because the costs of further controls in those options 

were large in comparison to the potential risk reduction. 

CAA § 112(d)(6) reviews must be considered an extension of the main purpose of 

§ 112, to reduce the public’s risk from exposure to air toxics, not the imposition of 

new technology for technology’s sake. EPA also notes that: 

 [t]his approach results in clearer and more effective implementation because 

only one part 63 NESHAP would apply to the source category, and is supported 

by the fact that Section 112(d)(6) refers to ‘emission standards promulgated 

under this section’ (emphasis added), as opposed to ‘subsection,’ in defining 

the scope of EPA's authority to review and revise standards. [71 Fed. Reg. 

34437] 

EPA stated in the final rule affecting the Butyl Rubber and EPR source categories 

that in the technology review EPA: 

... is not precluded from considering additional relevant factors, such as costs 

and risk.... For example, when a section 112(d)(2) MACT standard alone 

obtains protection of public health with an ample margin of safety and prevents 

adverse environmental effects, it is unlikely that it would be “necessary” to 

revise the standard further... [73 Fed. Reg. 76226] 

L. EPA has the authority to limit the conditions under which EPA revises an 

emission standard under CAA § 112(d)(6) and to base that revision on the 

residual risk decision framework. 

As EPA correctly pointed out in the proposed HON rule, § 112(d)(6) provides the 

Administrator with the discretion to decide the factors to consider in determining 

whether a revision to a MACT standard is necessary. 

 

Section 112(d)(6) of the CAA requires us to review and revise MACT 

standards, as necessary, every 8 years, taking into account developments in 

practices, processes, and control technologies that have occurred during that 

time. This authority provides us with broad discretion to revise the MACT 

standards as we determine necessary, and to account for a wide range of 

relevant factors. 

We do not interpret § 112(d)(6) as requiring another analysis of MACT floors for 

existing and new sources. Rather, we interpret the provision as essentially 

requiring us to consider developments in pollution control in the industry 
71

(“taking into account developments in practices, processes, and control 

technologies''), and assessing the costs of potentially stricter standards 

reflecting those developments (69 FR 48351). As the U.S. Court of Appeals for 

the DC Circuit has found regarding similar statutory provisions directing EPA to 

reach conclusions after considering various enumerated factors, we read this 

provision as providing EPA with substantial latitude in weighing these factors 

and arriving at an appropriate balance in revising our standards. This discretion 

also provides us with substantial flexibility in choosing how to apply modified 

standards, if necessary, to the affected industry. 

71 Fed. Reg. 34436-7 

Although the language of § 112(d)(6) is nondiscretionary regarding periodic review, 

it grants EPA much discretion to revise the standards “as necessary.” Thus, 

although the specifically enumerated factors that EPA should consider all relate to 

technology (e.g., developments in practices, processes and control technologies), 

the instruction to revise “as necessary” indicates that EPA is to exercise its 

judgment in this regulatory decision, and is not precluded from considering 

additional relevant factors, such as costs and risk. EPA has substantial discretion 

in weighing all of the relevant factors in arriving at the best balance of costs and 

emissions reduction and determining what further controls, if any, are necessary. 

This interpretation is consistent with numerous rulings by the U.S. Court of Appeals 

for the DC Circuit regarding EPA's approach to weighing similar enumerated 

factors under statutory provisions directing the agency to issue technology-based 

standards. See, e.g. Husqvarna AB, v. EPA, 254 F.3d 195 (DC Cir. 2001). 71 

Fed. Reg. 34437. 

Congress gave EPA discretion in revising MACT standards “as necessary,” so long 

as EPA takes into account technology changes. As EPA notes, it has the authority 

to balance relevant factors, giving greater weight to the goal of § 112. Moreover, 

Congress expressly provided for EPA to consider health risks in establishing 

MACT standards. Section 112(d)(4) grants the Administrator the authority to 

consider health thresholds “with an ample margin of safety” when establishing 

emissions standards under § 112(d). 

Further, Congress clearly sought to have § 112(f) inform § 112(d). Nothing in § 

112 indicates that Congress sought to establish two different sets of “emissions 

standards” for hazardous air pollutants. As EPA correctly notes, § 112(f)(2) would 

require revised emission standards under (d) “if the agency determines residual 

risk so justifies under (f)(2).” 71 Fed. Reg. 34,437. As EPA indicated, this 

approach would result in clearer and more effective implementation because only 

one Part 63 NESHAP would apply to the source category.

EPA has determined that § 112(f)(2) allows the Agency to revise the relevant 

MACT standard if further controls are warranted to reduce residual risks. As a 

practical matter, if EPA concludes that there are no major changes that would 

significantly alter EPA’s original estimates of risk that were used as a basis for 

EPA’s determination of ample margin of safety, then EPA should conclude that a 
72

revision is unnecessary because the source category presents risks that are both 

acceptable and protective with an ample margin of safety. 

Congress’ overall objective in establishing § 112 was to assure that residual HAP 

emissions from MACT regulated sources are controlled to a level that is 

considered “safe” or “acceptable.” This means reducing risks to levels EPA 

determined are “acceptable” in accordance with step one of the decision 

framework included in the 1989 Benzene NESHAP rule. It does not mean 

eliminating all risk or even requiring that all sources reduce their risks to levels less 

than one-in-a million. 

The legislative history of the 1990 CAA Amendments shows that Congress 

repeatedly rejected imposing controls beyond levels considered safe and 

protective of public health because they would impose regulatory costs without 

providing any public health benefit. Under § 112(d)(4), EPA has the authority to 

consider a “health threshold, with an ample margin of safety,” when establishing 

MACT standards. See S. 101-228, Dec. 20, 1989, at 520. Congress explained 

that the purpose of the provision was to ensure that MACT standards are not more 

stringent than necessary to protect human health in order to avoid unnecessary 

expenditures: 

To avoid expenditures by regulated entities which secure no public health or 

environmental benefit, the Administrator is given discretionary authority to 

consider the evidence for a health threshold higher than MACT at the time the 

standard is under review. [Id. at 171] 

Congress recognized that once EPA determined an acceptable level of risk—i.e., a 

health threshold with an ample margin of safety (in this instance without the 

consideration of costs)—it need not reassess control technology. This can be 

compared to the determination under § 112(f) to establish first an “acceptable” or 

“safe” level of risk without consideration of costs, followed by an ample margin of 

safety determination. 

[T]he Administrator has two options to use in assuring that low priority 

regulation will not be required [under section 112(c)(5) and 112(d)(4)]. . . . 

Again, there is a means to avoid regulatory costs which would be without public 

health benefit. [S. Rep. No. 101-228, at 175-76] 

Congress also clearly rejected provisions that would have required all sources to 

meet a 1-in-1 million standard. Any proposed interpretation of § 112(d)(6) as 

requiring successive reviews unless sources achieve this risk level implies that 

sources must ultimately meet a 1-in-1 million risk standard in order to avoid further 

regulation. There is no legislative history from the 1990 CAA Amendments that 

suggests Congress expected EPA to revise MACT standards after a residual risk 

determination has been made that the risks presented are “acceptable” and protect 

the public health with an ample margin of safety (either as a result of residual risk 

determination or through promulgation of a residual risk standard). There is no 

discussion as to the factors to be considered once an “acceptable” risk level or 

level deemed protective with an “ample margin of safety” has been reached. 
73

Congress, in fact, expressed a clear concern for the opposite – the waste of 

resources to reduce risks below levels considered safe. 

If Congress had intended a separate “technology-based” ratchet, then there would 

have been no need for § 112(f). As EPA noted in the Coke Oven Rule: 

we reiterate that there is no indication that Congress intended for section 

112(d)(6) to inexorably force existing source standards progressively lower and 

lower in each successive review cycle, the likely result of requiring successive 

floor determinations. [70 Fed. Reg. 20008] 

Further controls would have the effect of requiring additional emission reductions 

from sources that EPA believes are already sufficiently controlled to protect the 

public health with an ample margin of safety. Requiring further emission 

reductions from these sources would be a waste of public and private resources, 

and have no appreciable impact on public health. 

M. A review under CAA §112(d)(6) is not required if the post-MACT emission 

levels result in risks that are deemed to be protective of public health with an 

ample margin of safety, making any revisions under § 112(d)(6) not 

necessary. 

EPA should exempt source categories for which the post-MACT emission levels 

are protective of public health with an ample margin of safety: 

For example, when a section 112(d)(2) MACT standard alone obtains 

protection of public health with an ample margin of safety and prevents adverse 

environmental effects, it is unlikely that it would be “necessary” to revise the 

standard further, regardless of possible developments in control options. Thus, 

the Section 112(d)(6) review would not need to entail a robust technology 

assessment. Note that the circumstances discussed above presume that the 

facts surrounding the ample margin of safety and environmental analyses have 

not significantly changed. If there have been significant changes to 

fundamental aspects of the risk assessment then subsequent section 112(d)(6) 

reviews with robust technology assessments (and relevant risk considerations) 

may be appropriate. [71 Fed. Reg. 34437] 

Because some source categories have already been found to be protective of 

public health with an ample margin of safety, it is proper to create a presumption 

that these sources should not be subject to further review under § 112(d)(6). To 

reduce regulatory uncertainty, however, EPA should further clarify that the nature 

of the “significant changes to fundamental aspects of the risk assessment” that 

might trigger a review under § 112(d)(6) are changes that are likely to increase the 

estimates of risk by orders of magnitude. 

N. If EPA does undergo a review under CAA § 112(d)(6), the review should be 

limited to evaluating significant changes in technology/work practices -- not 

changing applicability thresholds. 
74

CAA § 112 (d)(6) indicates the scope of the (d)(6) technology review: 

 

Review and Revision - The Administrator shall review, and revise as necessary 

(taking into account developments in practices, processes, and control 

technologies), emission standards promulgated under this section no less than 

every 8 years. 

It is our view that the scope of the § 112(d)(6) review should be to assess 

advances in work practices and control technologies to determine if there are 

fundamental technology changes that could result in a step-change reduction in 

costs relative to the currently employed technology. The Agency would then need 

to determine the appropriateness of applying new requirements to 

new/reconstructed sources, or whether retrofits on existing sources are justifiable, 

which is a higher hurdle due to the cost and complexity of retrofitting existing 

sources that are already controlled. 

With most control technologies (e.g. thermal oxidation, flares, steam strippers) 

there continue to be only incremental improvements in efficiency, design and 

reliability (e.g. via metallurgy changes), none of which represent a significant 

change in work practices or control technologies. In these cases, no further 

controls via § 112(d)(6) should be prescribed. 

We do not believe that the § 112(d)(6) review should be based on changing 

applicability thresholds. For example, expanding rule applicability by reducing 

tanks size or vapor pressure cutoffs in applicability determinations, or increasing a 

TRE cutoff independent of technology advances should not be considered. This 

approach has nothing to do with developments in practices, processes, and control 

technologies and is not indicated in the CAA as a basis for the technology review. 

EPA already made applicability determinations in the original MACT rules by 

evaluating the floor and “beyond-the-floor” options. Again, nothing in the statute 

warrants review of these determinations and EPA should not use § 112(d)(6) to 

modify the original MACT floor analysis by changing applicability thresholds. 

Changes in applicability thresholds should only be considered in the § 112(f) risk 

standards if justified to reduce risk. 

O. If a technology review is warranted, EPA’s approach to the scope of the 

technology review is appropriate 

In this proposal EPA summarizes how a technology review will be performed. The 

approach appears to be consistent with the approach used in prior § 112(d)(6) 

reviews. First, the Agency determines if there have been any “developments in 

practices, processes, and control technologies” by drawing on Agency experience, 

reviewing technology databases, and requesting information from industry. If such 

developments are available, then the Agency will conduct an analysis of the 

technical feasibility of requiring the implementation of the developments along with 

the impacts in areas such as costs, emission reductions, and risk reduction. The 

Agency has defined a “development” as: 
75

1. Any add on control technology or other equipment that was not identified and 

considered during MACT development; 

2. Any improvements in add-on control technology or other equipment (that was 

identified and considered during MACT development) that could result in 

significant additional emission reductions; 

3. Any work practice or operational procedure that was not identified and 

considered during MACT development; and 

4. Any process changes or pollution prevention alternative that could be broadly 

applied that was not identified and considered during MACT development. 
December 6, 2010

Comments Submitted Electronically 

Email: a-and-r-Docket@epa.gov

Attention Docket ID Number EPA-HQ-OAR-2010-0600

Re: Docket ID Number EPA-HQ-OAR-2010-0600; Comments on Proposed National 

Emission Standards for Marine Tank Vessel Loading Operations and Pharmaceuticals 

Production

Dear Sir/Madam:

The Dow Chemical Company (Dow) appreciates the opportunity to comment on EPA’s 

proposed rule revisions for the subject source categories. 

Dow is a diversified chemical company that harnesses the power of innovation, science 

and technology to constantly improve what is essential to human progress. Dow owns 

and operates a number of sources across the United States that could be impacted by this 

proposal. 

Dow is generally supportive of ongoing efforts to improve air quality in the United States 

and has made significant investments to reduce emissions of both criteria and hazardous 

air pollutants over the last two decades. We have reviewed EPA’s October 21, 2010 

proposal and have prepared the attached comments for EPA's consideration. Dow is 

especially concerned about EPA's proposed regulatory text that would establish criteria 

for asserting an affirmative defense for excess emissions that are caused by malfunctions. 

Our comments on these provisions are contained under the Pharmaceuticals Production 

MACT - Subpart GGG comments, but the same comments apply to the parallel 

affirmative defense language proposed under each subpart.

If you have questions concerning the attached, please contact me at (361) 553-2920 or 

email: wozniara@dow.com.

Sincerely,

Russell A. Wozniak

EH&S Global Regulatory Affairs

The Dow Chemical Company
Attachment 

cc: 

Mr. Steve Shedd, Energy Strategies Group, Sector Policies and Programs Division, 

Office of Air Quality Planning and Standards, US Environmental Protection Agency -

email: shedd.steve@epa.gov

Mr. Randy McDonald, Energy Strategies Group, Sector Policies and Programs Division, 

Office of Air Quality Planning and Standards, US Environmental Protection Agency -

email: mcdonald.randy@epa.gov
Comments on

EPA’s Proposed Rule

National Emission Standards for Hazardous Air Pollutants 

for Marine Tank Vessel Loading Operations and 

Pharmaceuticals Production

75 FR 65068, October 21, 2010

Docket EPA-HQ-OAR-2010-0600

Submitted by

The Dow Chemical Company 

December 6, 2010
Dow Chemical Comments Page 1

Docket EPA-HQ-OAR-2010-0600

Comments on Marine Tank Vessel Loading Operations -

40 CFR 63 Subpart Y

1. A correction is needed in the proposed language of Subpart Y to add §63.560(f) 

concerning the submerged loading requirement and to reference the new provisions 

in §63.562(f)(1) or (f)(2) for marine terminals that load more than 1 million 

barrels/yr of gasoline.

Before publication of the October 21, 2010 proposed rule, EPA indicated an intent to 

propose submerged fill as the floor level of control for two MTVLO subcategories (i.e.,

those facilities emitting less than 10/25 TPY of HAP and those facilities located more 

than 0.5 miles from shore), for which the current NESHAP does not include emission 

standards. However, paragraph (f) in §63.560 appears to have been inadvertently left out 

of the proposed rule

Based on correspondence with Mr. Steve Shedd of EPA, it is our understanding that 

agreed that a new proposed paragraph (f) is missing in section 63.560. EPA’s intent was 

to require not only submerged fill, but also the control of marine terminals that load more 

than one million barrels of gasoline. The proposed rule text should read as follows:

(f) A source referred to this paragraph by (a)(1) or (2) of this section, must meet 

(f)(1) and (2) of this section.

(1) The submerged fill standards of 46 CFR 153.282, and

(2) The provisions of §63.562(f)(1) or §63.562(f)(2), if the terminal loads 

more than 1 million barrels (M barrels) of gasoline.

Note: The proposed rule does include submerged fill requirement for marine tank vessel 

loading operations at existing offshore loading terminals in proposed §63.560(d)(6)(i).
Dow Chemical Comments Page 2

Docket EPA-HQ-OAR-2010-0600

2. Instead of referencing 46 CFR §153.282 in §§63.560(d)(6)(i) and 63.560(f)(1), 

EPA should directly cite the actual specification for the submerged fill line.

46 CFR §153.282 specifies that for cargo filling lines, “The discharge point of a cargo 

tank filling line must be no higher above the bottom of the cargo tank or sump than 10 cm 

(approx. 4 in.) or the radius of the filling line, whichever is greater.”

Although it is helpful to know the basis of this specification, the Marine MACT should 

directly specify the submerged filling standard within Subpart Y for the following 

reasons:

1. Based on information from Kirby Inland Marine LP, 46 CFR §153.282 is strictly 

a regulation governing tank ships and is not applicable to tank barges. 

2. Referencing the Coast Guard rules could cause issues if that particular section 

(§153.282) is later revised. EH&S personnel responsible for tracking changes to 

the EPA regulations such as the Marine MACT are usually not the same people 

that track changes to the Coast Guard rules. Including the submerged filling line 

specifications directly in the Marine MACT simplifies compliance by eliminating 

the need to reference the Coast Guard rules.

Based on the previous comment, when EPA adds paragraph (f) to section 63.560, Dow 

recommends the following language:

(f) A source referred to this paragraph by (a)(1) or (2) of this section, must meet (f)(1) 

and (2) of this section.

(1) The submerged fill standards of 46 CFR 153.282 The discharge point of a 

cargo tank filling line must be no higher above the bottom of the cargo tank 

or sump than 10 cm (approx. 4 in.) or the radius of the filling line, whichever 

is greater, and

(2) The provisions of §63.562(f)(1) or §63.562(f)(2), if the terminal loads more 

than 1 million barrels (M barrels) of gasoline.

Similar language should also be added to the proposed §63.560(d)(6)(i) instead of 

referencing 46 CFR §153.282.
Dow Chemical Comments Page 3

Docket EPA-HQ-OAR-2010-0600

3. EPA should clarify that Section 63.562(e) does not apply to existing Sources with 

emissions less than 10 and 25 tons (since the emission limits do not apply) and 

that only Sections 63.560(f)(1) [new section], 63.567(j)(4) and 63.565(l) apply as per 

§63.560(a)(3). 

As proposed, Section 63.562(a)(2) states that existing sources with emissions less than 10 

and 25 tons are not subject to the emission standards in §63.562(b) and (d), except as 

specified in paragraph (f) [submerged fill]. 

Section 63.562(a)(3) implies that only the recordkeeping requirements in §63.567(j)(4) 

and the emission estimation requirements in §63.565(l) apply to these sources, except as

specified in paragraph (f) [submerged fill].

§ 63.560 Applicability and designation of affected source.

(a) Maximum achievable control technology (MACT) standards. 

(2) Existing sources with emissions less than 10 and 25 tons are not subject to the 

emissions standards in §63.562(b) and (d), except as specified in paragraph (f) of 

this section.

(3) The recordkeeping requirements of §63.567(j)(4) and the emission estimation 

requirements of §63.565(l) apply to existing sources with emissions less than 10 

and 25 tons, except as specified in paragraph (f) of this section.

The way §63.560(a)(2) is worded, one might conclude that §63.562(e) applies to existing 

sources with emissions less than 10 and 25 tons. However, §63.560(a)(3) could again 

lead one to conclude that only those citations mentioned are applicable to sources with 

emissions less than 10 and 25 tons.

Section 63.562(e) pertains to operation and maintenance requirements for air pollution 

control equipment and monitoring equipment for affected sources. At all times, including 

periods of startup, shutdown, and malfunction, a facility is required to operate and 

maintain a source, including associated air pollution control equipment, in a manner 

consistent with safe and good air pollution control practices for minimizing emissions. 

This section requires development of a written operation and maintenance plan that 

describes in detail a program of corrective action for varying (i.e., exceeding baseline 

parameters) air pollution control equipment and monitoring equipment, based on 

monitoring requirements in §63.564, used to comply with these emissions standards. The 

plan shall also identify all routine or otherwise predictable continuous monitoring system 

(e.g., thermocouples, pressure transducers, continuous emissions monitors (CEMS)) 

variances. Because the emission standards do not apply to existing sources with 

emissions less than 10 and 25 tons, one could conclude that the operation and 
Dow Chemical Comments Page 4

Docket EPA-HQ-OAR-2010-0600

maintenance requirements for air pollution control equipment and monitoring equipment 

do not apply either. 

In addition, the proposed changes to the Marine MACT include adding paragraph (7) to 

§63.562(e) to address recordkeeping and reporting requirements during periods of 

malfunction. The rule also is proposing an affirmative defense against civil penalties for 

exceedances of emission standards caused by malfunctions, as well as the criteria for 

establishing the affirmative defense. Because §63.560(a)(2) specifically states that the 

emission standards in §63.562(b) and (d) do not apply to existing sources with emissions 

less than 10 and 25 tons, then the affirmative defense requirements proposed in 

§63.562(e)(7) for exceedances of the emission standards caused by malfunctions should 

not apply either.

Dow recommends that the language in §63.560(a)(3) be revised to state:

(a)(3) Only the recordkeeping requirements in §63.567(j)(4) and the emission 

estimation requirements of §63.565(l) apply to existing sources with emissions 

less than 10 and 25 tons, except as specified in paragraph (f) of this section. No 

other requirements in this subpart apply to existing sources with emissions 

less than 10 and 25 tons.
Dow Chemical Comments Page 5

Docket EPA-HQ-OAR-2010-0600

4. In the emission estimation procedures Under §63.565(l), Dow requests that EPA 

clarify that the exclusion for “Commodities Exempted by §63.560(d)” was intended 

to mean that annual HAP emissions do not need to be estimated from marine tank 

vessel loading operations that meet any of the exemptions provided in §63.560(d).

For existing sources with emissions less than 10 and 25 tons, Section 63.560(a)(3) 

requires complying with the recordkeeping requirements in §63.567(j)(4) and the 

emission estimation requirements in §63.565(l) (in addition to the proposed §63.560(f)).

Section 63.565 requires calculating an annual estimate of HAP emissions from marine 

tank vessel loading operations, excluding “commodities” exempted by §63.560(d).

Section 63.560(d) provides several exemptions from the MACT and RACT standards and 

only uses the term “commodity” in the §63.560(d)(1) for emissions resulting from marine 

tank vessel loading operations of “commodities” with vapor pressures less than 10.3 

kilopascals (kPa) (1.5 pounds per square inch, absolute) (psia) at standard conditions, 20 

C and 760 millimeters Hg (mm Hg).

Other exemptions provided in §63.560(d) that should be excluded from the annual 

emission estimation requirement include:

• Marine tank vessel loading operations where emissions are reduced by using a 

vapor balancing system [§63.560(d)(2)]. 

• Marine tank vessel loading operations that are contiguous with refinery operations 

at sources subject to and complying with subpart CC of this part, National 

Emissions Standards for Organic Hazardous Air Pollutants from Petroleum 

Refineries [§63.560(d)(3)]

• Benzene emissions from marine tank vessel loading operations that are subject to 

and complying with 40 CFR part 61, subpart BB, National Emissions Standards 

for Benzene Emissions from Benzene Transfer Operations [§63.560(d)(4)]

• Marine tank vessel loading operations at loading berths that only transfer liquids 

containing organic HAP as impurities [§63.560(d)(5)]

• Marine tank vessel loading operations at existing offshore loading terminals 

[§63.560(d)(6)]

• Ballasting operations [§63.560(d)(7)]

EPA could improve the language in §63.565(l) by rewording it as follows:

(l) Emission estimation procedures. For sources with emissions less than 10 or 25 tons 

and sources with emissions of 10 or 25 tons, the owner or operator shall calculate an 

annual estimate of HAP emissions, excluding commodities emissions from marine tank 

vessel loading operations exempted by §63.560(d), from marine tank vessel loading 

operations.
Dow Chemical Comments Page 6

Docket EPA-HQ-OAR-2010-0600

Regulatory Language Associated with this Comment

§ 63.565 Test methods and procedures.

(l) Emission estimation procedures. For sources with emissions less than 10 or 25 tons 

and sources with emissions of 10 or 25 tons, the owner or operator shall calculate an 

annual estimate of HAP emissions, excluding commodities exempted by §63.560(d), 

from marine tank vessel loading operations. Emission estimates and emission factors 

shall be based on test data, or if test data is not available, shall be based on measurement 

or estimating techniques generally accepted in industry practice for operating conditions 

at the source.

§ 63.567 Recordkeeping and reporting requirements.

(j) Emission estimation reporting and recordkeeping procedures. The owner or operator 

of each source complying with the emission limits specified in §63.562(b)(2), (3), and (4) 

shall comply with the following provisions:

(4) Owners or operators of marine tank vessel loading operations specified in 

§63.560(a)(3) shall retain records of the emissions estimates determined in 

§65.565(l) and records of their actual throughputs by commodity, for 5 years.

§ 63.560 Applicability and designation of affected source.

(d) Exemptions from MACT and RACT standards. 

(1) This subpart does not apply to emissions resulting from marine tank vessel 

loading operations, as that term is defined in §63.561, of commodities with vapor 

pressures less than 10.3 kilopascals (kPa) (1.5 pounds per square inch, absolute) 

(psia) at standard conditions, 20 °C and 760 millimeters Hg (mm Hg).

(2) The provisions of this subpart pertaining to the MACT standards in 

§63.562(b)(2), (3) and (4) and to the RACT standards in §63.562(c)(3) and (4) do 

not apply to marine tank vessel loading operations where emissions are reduced 

by using a vapor balancing system, as that term is defined in §63.561. The 

provisions pertaining to the vapor collection system, ship-to-shore compatibility, 

and vapor tightness of marine tank vessels in §63.562(b)(1) and (c)(2) do apply.

(3) The provisions of this subpart pertaining to the MACT standards in 

§63.562(b)(2), (3), and (4) do not apply to marine tank vessel loading operations 

that are contiguous with refinery operations at sources subject to and complying 

with subpart CC of this part, National Emissions Standards for Organic 

Hazardous Air Pollutants from Petroleum Refineries, except to the extent that any 

such provisions of this subpart are made applicable by subpart CC of this part.
Dow Chemical Comments Page 7

Docket EPA-HQ-OAR-2010-0600

(4) The provisions of this subpart pertaining to the MACT standards in 

§63.562(b) and (d) do not apply to benzene emissions from marine tank vessel 

loading operations that are subject to and complying with 40 CFR part 61, subpart 

BB, National Emissions Standards for Benzene Emissions from Benzene Transfer 

Operations, except that benzene emissions or other HAP emissions (i.e., 

nonbenzene HAP emissions) from marine tank vessel loading operations that are 

not subject to subpart BB are subject to the provisions of this subpart.

(5) The provisions of this subpart pertaining to the MACT standards in 

§63.562(b) and (d) do not apply to marine tank vessel loading operations at 

loading berths that only transfer liquids containing organic HAP as impurities, as 

that term is defined in §63.561.

(6) The provisions of this subpart do not apply to marine tank vessel loading 

operations at existing offshore loading terminals, as that term is defined in 

§63.561, except existing offshore loading terminals must meet paragraph (d)(6)(i) 

and (ii) of this section.

(i) The submerged fill standards of 46 CFR §153.282, and

(ii) The provisions of §63.562(f)(1) or §63.562(f)92), if the terminal loads 

more than 1 million barrels (M barrels) of gasoline. [Proposed 

10/21/2010]

(7) The provisions of this subpart do not apply to ballasting operations, as that 

term is defined in §63.561.
Dow Chemical Comments Page 8

Docket EPA-HQ-OAR-2010-0600

Comments on Pharmaceuticals Production - 40 CFR 63 Subpart GGG

1. The definition of a malfunction does not specify the duration of the event as being 

“short.” Therefore, the affirmative defense language should be consistent.

On page 65146 of the October 21, 2010 proposed rule, EPA proposed changes to 40 CFR

§63.1250(g)(4) to include affirmative defense language. In §63.1250(g)(4)(i)(A), EPA 

states that to establish the affirmative defense, the excess emissions were caused by a 

“sudden, short

§63.1251

, infrequent, and unavoidable...” However, the definition of malfunction in 

§63.1251 does not specify the duration of the malfunction event. Therefore, EPA should 

not add this type of restriction to this definition in the context of the proposed affirmative 

defense requirements, but should maintain consistency with the definition of malfunction 

in the Pharma MACT rule. 

Malfunction means any sudden, infrequent, and not reasonably preventable failure 

of air pollution control equipment, emissions monitoring equipment, process 

equipment, or a process to operate in a normal or usual manner which causes, or 

has the potential to cause, the emission limitations in an applicable standard to be 

exceeded. Failures that are caused all or in part by poor maintenance or careless 

operation are not malfunctions.

2. The affirmative defense requirements specified are unreasonable, difficult to 

prove, and subject to interpretation. At a minimum, EPA should make the revisions 

noted below to these provisions. 

On page 65146 of the October 21, 2010 proposed rule, EPA proposes that nine 

requirements be met (not including additional notification requirements) in order for a 

facility to claim an affirmative defense in a malfunction situation. Some of these

requirements are unreasonable, difficult to prove, and subject to varying interpretation. 

Dow suggests the following revisions to these paragraphs and others and provides

supporting rationale for these revisions on the next pages: 
Dow Chemical Comments Page 9

Docket EPA-HQ-OAR-2010-0600

Suggested Revisions to 40 CFR §63.1250(g)(4)

(4) In response to an action to enforce the standards set forth in this subpart, you 

may assert a civil defense to a claim for civil penalties for exceedances of such standards 

that are caused by a malfunction, as defined in §63.2. Appropriate penalties may be 

assessed, however, if the respondent fails to meet its burden of proving all the 

requirements in the affirmative defense. The affirmative defense shall not be available 

for claims for injunctive relief.

(i) To establish the affirmative defense in any action to enforce such a limit, the 

owners or operators of facilities must timely meet the notification requirements of 

paragraph (4)(ii) of this subsection, and must prove by a preponderance of evidence that:

Comment - See later comments on concerns with notification requirements 

especially for very small emissions associated with small malfunctions. Failure to 

notify simply should not negate the ability of the regulated entity to assert an 

affirmative defense especially for very small excess emission events. 

(A) The excess emissions were caused by a sudden, short, infrequent, and 

unavoidable failure of air pollution control and monitoring equipment, or a process to 

operate in a normal and usual manner; and could not have been prevented through careful 

planning, proper design or better operation and maintenance practices; and did not stem 

from any activity or event that could have been foreseen and avoided, or planned for; and 

were not part of a recurring pattern indicative of inadequate design, operation, or 

maintenance; and

Comment - As previously noted in these comments, the duration of an excess 

emission event should not be an element for asserting the affirmative defense. Some 

excess emission events may last for a period of seconds while others may be longer 

in duration such as a mechanical failure that results in the need to shutdown and 

purge process equipment. 
Dow Chemical Comments Page 10

Docket EPA-HQ-OAR-2010-0600

Comment - The term "infrequent" is subject to different interpretations by 

regulatory agencies and should be evaluated on a case-by-case basis and removed 

from the regulation text. 

Comment - The Affirmative Defense should also be available for a 

malfunction of required monitoring equipment or EPA should clarify in these rules 

that a malfunction of monitoring equipment that does not result in excess emissions 

does not need to be treated as a malfunction. 

(B) Repairs were made as expeditiously as possible when the applicable emission 

limitations were being exceeded. Off-shift and overtime labor were used, to the extent 

practicable to make these repairs; and

Comment - The sentence regarding the use of "off-shift and overtime labor" 

should be deleted from this paragraph and flexibility provided to allow a regulated 

entity to repair and respond to equipment malfunctions in an expeditious and 

appropriate manner. In some cases, a short period of engineering/design work 

and/or planning must be part of the effort to repair equipment and the immediate 

use of off-shift and overtime labor may not always be appropriate. Responding to 

malfunctions is many times a case-by-case situation depending on the specifics of the 

malfunction and equipment to be repaired. 

(C) The frequency, amount and duration of the excess emissions (including any 

bypass) were minimized to the maximum extent practicable during periods of such 

emissions; and 

(D) If the excess emissions resulted from a bypass of control equipment or a 

process, then the bypass was unavoidable to prevent loss of life, severe personal injury, 

or severe property damage; and 

Comment - EPA should exclude the word "severe" from paragraph (D) as 

evaluating severe vs. non-severe property damage is highly subjective and open to a 

wide range of interpretations. In addition, the term "severe" personal injury is 

also highly subjective vs. "non-severe" personal injury. 
Dow Chemical Comments Page 11

Docket EPA-HQ-OAR-2010-0600

(E) All possible steps were taken to minimize the impact of the excess emissions 

on ambient air quality, the environment, and human health; and 

(F) All emissions monitoring and control systems were kept in operation if at all 

possible; and 

(G) Your actions in response to the excess emissions were documented by 

properly signed, contemporaneous operating logs; and

Comment - A large number of Dow plants use some form of electronic media 

to document actions in response to excess emissions. Imposing a requirement to 

print and sign a record of such action is outdated if one can document the response 

to actions in an electronic format. 

(H) At all times, the facility was operated in a manner consistent with good 

practices for minimizing emissions; and

Comment - EPA needs to further define the term "facility" in this context. 

For example, does the term cover the "affected facility" as defined in the Part 63 

Rule or does the term cover the specific piece of equipment or a control device 

where the malfunction occurs? 

(I) The owner or operator has prepared a written root cause analysis to determine, 

correct and eliminate the primary causes of the malfunction and the excess emissions 

resulting from the malfunction event at issue. The analysis shall also specify, using the 

best monitoring methods and engineering judgment, the amount of excess emissions that 

were the result of the malfunction.

Comment - EPA should require a formal root cause analysis for larger excess 

emission events, but should provide some flexibility in these provisions for smaller 

malfunctions where a small amount of excess emissions occur. An example of a 

smaller event is the development of a pinhole leak in process piping that is not

covered by a LDAR provision in the rule. The cause of the smaller events should be 

determined, but perhaps a formal root cause analysis is not warranted for all 

smaller events. 
Dow Chemical Comments Page 12

Docket EPA-HQ-OAR-2010-0600

3. The affirmative defense notification requirements are unreasonable, repetitive 

and contradict other regulatory requirements. 

On page 65146 of the October 21, 2010 proposed rule, EPA proposes that notification 

requirements be met in order for a facility to claim the affirmative defense. These 

requirements include an immediate notification by telephone or FAX no later than 2 

business days after the initial occurrence of the malfunction and a written report to the 

Administrator within 30 days. The 30 day report requires the facility to demonstrate that 

the requirements specified in (g)(4)(i) be met. 

The immediate notification (within 2 business days) should be eliminated for at least the 

following reasons: 

• It is burdensome and duplicative of emergency response reporting procedures 

under SARA/CERCLA/EPCRA, as well as many State regulations for larger 

excess emission events. 

• This new requirement will contradict many existing reporting rules by requiring 

the reporting of emission quantities well below CERCLA/SARA/State Agency 

Reportable Quantities. Thus, the agency will be flooded with reports of very 

small excess emissions. 

• The rule structure encourages reporting to the agency even if the owner/operator 

is not sure if an exceedance of an emission limit has occurred for fear of not being 

able to claim the affirmative defense. Thus, agency reporting systems will 

become "clogged" with insignificant reports further complicating the ability of all 

resources to respond to a larger event. 

• The rule is not clear to whom the reports should be submitted (e.g., the EPA 

Regional Office, State or Local Agency, LEPC).

In addition, the 30 day reporting requirement requires information that is already required 

to be submitted in the semi-annual (periodic) report under the Pharma MACT as 

specified in §63.1260(g). Therefore, by imposing this redundant requirement, EPA is 

requiring that the information be submitted twice. The periodic report requires 

information be submitted for malfunction events in which excess emissions have 

occurred, including the nature and cause of any malfunctions and the corrective actions 

taken. Additionally, Title V reporting requirements include reporting of events in which 

emission limits have been exceeded. Therefore, this requirement is duplicative in nature 

and should be eliminated. 
Dow Chemical Comments Page 13

Docket EPA-HQ-OAR-2010-0600

4. The proposed changes to the performance test language in the Pharma MACT is 

too vague and should be clarified. 

The following proposed language on page 65147 of the October 21, 2010 proposed rule 

related to performance testing is too vague: “Performance testing 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. Upon 

request, the owner or operator shall make available to the Administrator such records as 

may be necessary to determine conditions of performance tests.”

Based on this language, it would seem that EPA intends to write the test plan for the 

facility rather than allow the facility to develop emission profiles and identify worst case 

conditions for testing the control device as provided for in the rule. EPA (or the delegated 

authority) is already required to approve the facilities test plan. Therefore, this language 

seems to add another layer of oversight that is redundant and not needed.
INTERNATIONAL INSTITUTE OF SYNTHETIC RUBBER PRODUCERS, INC.

December 6, 2010 

Comments on EPA’s Proposed Rule: NESHAP Emissions for Group I Polymers and Resins; 

Residual Risk and Technology Reviews, 75 Fed. Reg. 65068 (October 21, 2010) 

 

Via Electronic Filing: a-and-r-docket@epa.gov

EPA Docket Center, EPA West (Air Docket) 

U.S. Environmental Protection Agency 

Mailcode: 2822T 

1200 Pennsylvania Ave., NW 

Washington, DC 20460 

Attention: Docket ID No. EPA-HQ-OAR-2010-0600

Dear Sir or Madam: 

 The International Institute of Synthetic Rubber Producers Inc. (IISRP) welcomes the 

opportunity to provide comments on EPA’s proposed rule, “National Emission Standards for 

Hazardous Air Pollutant Emissions: Hard and Decorative Chromium Electroplating and 

Chromium Anodizing Tanks; Group I Polymers and Resins; Marine Tank Vessel Loading 

Operations: Pharmaceuticals Production; The Printing and Publishing Industry; and Steel 

Pickling-HCl Process Facilities and Hydrochloric Acid Regeneration Plants.” 75 Fed. Reg. 

65068 (October 21, 2010). 

 IISRP represents the global synthetic rubber industry including nine members located in 

the US. We have worked collaboratively with EPA for almost two decades beginning with the 

development of the initial MACT standards for our industry in the early 1990’s. IISRP has 

coordinated plant visits with the EPA and its contractor in an effort to facilitate the regulatory 

process. IISRP’s comments are in response to the proposed Group I Polymers and Resins 

(P&R1) source category requirements. 

* * * * 

The IISRP has three major concerns. Our first concern is with the proposed requirements 

modifying the startup, shutdown, and malfunction (SSM) provisions 

The proposed SSM provisions represent a major departure from prior standard setting 

proposals. Under the proposed regulations, a single numerical emission limit would apply 

regardless of the status of the facility. The only relief from a penalty would be for a limited class 

of malfunctions, and then only if the owner or operator can demonstrate by a preponderance of 

the evidence that the malfunction meets each of a series of nine (9) separate criteria. See

proposed 40 CFR §§63.480(j)(4)(i)(A)-(I). (“Appropriate penalties may be assessed, however, if 

the respondent fails to meet its burden of proving all the requirements in the affirmative 

defense.”) Further, the burden of proving that the malfunction meets all of the nine criteria rests 

on the owner or operator. Proposed 40 CFR §§63.482 (b). (“Affirmative defense means, in the 

context of an enforcement proceeding, a response or a defense put forward by a defendant, 
 2 

regarding which the defendant has the burden of proof, and the merits of which are 

independently and objectively evaluated in a judicial or administrative proceeding.”). 

* * * * 

There is no legal requirement for a single, constant numerical emission standard 

applicable under all possible conditions. 

 As an initial legal matter, EPA is not required to establish a constant and inflexible 

numerical emission standard that applies at all times to facilities regulated under the NESHAPs 

program. The proposed rule cites the D.C. Circuit’s decision in Sierra Club v. EPA, 551 F.3d 

1019 (D.C. Cir. 2008), cert. denied, 130 S. Ct. 1735 (2010), which vacated the exemption for 

excess emissions during SSM events contained in the 40 C.F.R. part 63, subpart A General 

Provisions for NESHAPs under CAA section 112. The proposal states that the D.C. Circuit’s 

interpretation of the definition of “emission standards” means that the court decision “requires 

EPA to apply MACT emission standards on a continuous basis, thereby precluding exemptions 

applied for malfunctions or other singular events.” 75 Fed. Reg. at 63,282. 

 While the court decision may be read to require an emission standard during SSM events 

(“there must be continuous section 112-compliant standards” (551 F.3d at 1027)), however, 

nowhere does the decision prohibit EPA from issuing different emissions standards during SSM 

events as compared to normal operations. To the contrary, the opinion specifically 

acknowledges that the CAA’s broad definition of “emission standard” as including “any 

requirement relating to the operation or maintenance of a source to assure continuous emission 

reduction” suggests that EPA need not “necessarily continuously apply[] a single standard.” 551 

F.3d at 1027. 

 Existing precedent also fails to support the Agency’s unilateral approach of ignoring the 

obvious and inescapable emission impacts which occur when a facility is operating under SSM 

conditions. The D.C. Circuit has recognized that standards based on what sources achieve must 

account for the limitations inherent in the technology used to reduce emissions. For example, in 

a case reviewing NSPS under section 111 of the CAA, Portland Cement Ass’n v. Ruckelshaus, 

486 F.2d 375, 398 (D.C. Cir. 1973), the court acknowledged that “’startup’ and ‘upset’ 

conditions due to plant or emission device malfunction, is an inescapable aspect of industrial life 

and that allowance must be made for such factors in the standards that are promulgated.” Id. at 

399; see National Lime Ass’n v. EPA, 627 F.2d 416, 431 n.46 (D.C. Cir. 1980) (noting that “a 

uniform standard must be capable of being met under most adverse conditions which can 

reasonably be expected to recur”). The D.C. Circuit acknowledged this same principle when 

reviewing emission standards for new sources in the medical waste incinerator rule under section 

129 in Sierra Club v. EPA, 167 F.3d 658 (D.C. Cir. 1999). In that case, while the court did not 

find the record sufficient to support EPA’s approach for new sources, the D.C. Circuit did not 

object to a standard-setting approach which would account for the performance of technology 

under the “worst reasonably foreseeable circumstances.” See id. at 665. Furthermore, the D.C. 

Circuit reiterated the principle in National Lime that “where a statute requires that a standard be 

‘achievable,’ it must be achievable ‘under the most adverse circumstances which can reasonably 

be expected to recur.’” Id. at 665 (citing National Lime Ass’n v. EPA, 627 F.2d 416, 431 n.46 
 3 

(D.C. Cir. 1980)). EPA’s approach in the proposed Polymers and Resins I MACT ignores the 

existing legal principles by applying the standards at all times, including SSM conditions, but 

making no allowance in the emission standard applicable under these adverse and substantially 

differing conditions. Further, other than citing the Sierra Club v. EPA opinion, the proposal fails 

to provide an explanation justifying the outright deletion of any malfunction provisions. 

* * * * 

The proposed criteria for determining if a malfunction will not result in penalties 

are ambiguous, technically unrealistic, and unworkable. 

 Rather than making appropriate allowance for malfunctions in the emission standards 

applicable to the source categories, EPA proposes minimal relief for a limited subset of 

malfunctions through an “affirmative defense” to civil penalties. The proposed criteria for 

determining if a malfunction qualifies for the affirmative defense consist of a series of nine (9) 

tests that an unexpected malfunction condition must meet .1

 The proposed criteria include 

provisions that are inherently unattainable for exceedances that are a result of malfunctions. 

The first criterion is flawed in several respects. The first sentence of proposed 40 CFR 

63.480(j)(4)(i)(A) only permits use of the affirmative defense to a subset of malfunctions, those 

that are “short” and those that are “unavoidable” (as opposed to “not reasonably preventable.”) 

The criteria for using the affirmative defense should be identical to the criteria for a malfunction 

in the malfunction definition. Under subpart U, the definition of “malfunction” from 40 

CFR§63.2 applies. That definition is: “Malfunction means any sudden, infrequent, and not 

 

1 See proposed 40 CFR §63.480(j)(4) (“Appropriate penalties may be assessed, however, if the respondent fails to meet its 

burden of proving all the requirements in the affirmative defense. The affirmative defense shall not be available for claims for 

injunctive relief. 

 (i) To establish the affirmative defense in any action to enforce such a limit, the owners or operators of facilities must 

timely meet the notification requirements of paragraph (j)(4)(ii) of this section, and must prove by a preponderance of evidence 

that: 

 (A) The excess emissions were caused by a sudden, short, infrequent, and unavoidable failure of air pollution 

control and monitoring equipment, or a process to operate in a normal and usual manner; and could not have been prevented 

through careful planning, proper design, or better operation and maintenance practices; and did not stem from any activity or 

event that could have been foreseen and avoided, or planned for; and were not part of a recurring pattern indicative of inadequate 

design, operation, or maintenance; and 

 (B) Repairs were made as expeditiously as possible when the applicable emission limitations were being 

exceeded. Off-shift and overtime labor were used, to the extent practicable to make these repairs; and 

 (C) The frequency, amount, and duration of the excess emissions (including any bypass) were minimized 

to the maximum extent practicable during periods of such emissions; and 

 (D) If the excess emissions resulted from a bypass of control equipment or a process, then the bypass was 

unavoidable to prevent loss of life, severe personal injury, or severe property damage; and 

 (E) All possible steps were taken to minimize the impact of the excess emissions on ambient air quality, the 

environment, and human health; and 

 (F) All emissions monitoring and control systems were kept in operation if at all possible; and 

 (G) Your actions in response to the excess emissions were documented by properly signed, contemporaneous 

operating logs; and 

 (H) At all times, the facility was operated in a manner consistent with good practices for minimizing 

emissions; and 

 (I) The owner or operator has prepared a written root cause analysis to determine, correct, and eliminate the 

primary causes of the malfunction and the excess emissions resulting from the malfunction event at issue. The analysis 

shall also specify, using the best monitoring methods and engineering judgment, the amount of excess emissions that were the 

result of the malfunction.”)
 4 

reasonably preventable failure of air pollution control and monitoring equipment, process 

equipment, or a process to operate in a normal or usual manner which causes, or has the potential 

to cause, the emission limitations in an applicable standard to be exceeded. Failures that are 

caused in part by poor maintenance or careless operation are not malfunctions.” Any differences 

between the affirmative defense and the definition of malfunction are arbitrary and capricious as 

the Agency has not cited any basis for a difference. 

 

 The first criterion also requires that the excess emissions “could not have been prevented 

through careful planning, proper design, or better operation and maintenance practices; and did 

not stem from any activity or event that could have been foreseen and avoided, or planned for, 

and were not part of a recurring pattern indicative of inadequate design, operation, or 

maintenance.” Proposed 40 CFR §63.480(j)(4)(i)(A). In hindsight, after a malfunction occurs, it 

is usually possible to identify actions that would have prevented a malfunction. After the fact, 

preventing the malfunction can appear as simple as simply replacing a particular component 

earlier, or slightly modifying a specific design to include a redundant feature, or modifying the 

manufacturing process. 

 The flaw in this approach is that an owner or operator must design, operate, and maintain 

a facility without the benefit of hindsight. Decisions regarding the facility design, the 

maintenance schedules, and the manufacturing process must be made on a daily basis without the 

knowledge that comes with the occurrence of the malfunction. Owners and operators have a 

strong financial incentive to maintain a facility’s up-time and therefore use their best engineering 

judgment to minimize facility downtime due to malfunctions. By their very nature the vast 

majority of malfunctions are sudden and unexpected. In advance of such a malfunction, an 

owner or operator cannot know which design feature, component, or process parameters should 

be modified, replaced, or adjusted to prevent an unknown malfunction that might occur in the 

future. 

 As an illustration of the flaw in the proposed approach, consider a hypothetical 

exceedance caused by a valve failure. After the malfunction, it may be tempting to cite as the 

result of the exceedence a failure to replace the valve, perhaps at a cost of $1000, and to 

therefore conclude that the malfunction was preventable. However, before the malfunction it can 

be unclear whether particular components need to be replaced (example: valves, or tanks, or 

piping, or control equipment). Further, even if it appears based on the facility’s best engineering 

judgment that valves should be replaced first, it is also unclear which valve should be replaced. 

The cost to replace every valve in a large facility, at $1000 per valve, could be prohibitive and 

not cost-effective given the minimal size of the exceedance. 

 Furthermore, as written, a facility owner and operator is subject to potential penalties 

through no fault of their own. Penalties are allowed if the malfunctions “stem from any activity 

or event that could have been foreseen and avoided, or planned for.” Proposed 40 CFR 

§63.480(j)(4)(i)(A). (emphasis added). For facilities in particular geographic regions natural 

disasters are readily foreseeable (e.g., hurricanes, earthquakes, tornadoes). Under the proposed 

regulation, emission exceedances that result from such events would not qualify for the 

affirmative defense. This is simply because with the expenditure of sufficient funds it is 

technically possible to avoid or design for these events. While the resources required to prepare 
 5 

a facility for these types of events may be exorbitant, there is no cost ceiling in the criteria. The 

criterion is whether it is technically possible to have “foreseen and avoided, or planned for” the 

event and the resulting malfunction, not whether the cost of doing so is reasonable. 

Therefore under subpart U, the definition of “malfunction” from 40 CFR §63.2 applies. 

That definition is: “Malfunction means any 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 which causes, or has the potential to cause, the emission 

limitations in an applicable standard to be exceeded. Failures that are caused in part by poor 

maintenance or careless operation are not malfunctions.” The first sentence of proposed 40 CFR 

63.480(j)(4)(i)(A) only permits use of the affirmative defense to a subset of malfunctions, those 

that are “short” and those that are “unavoidable” (as opposed to “not reasonably preventable.”) 

The criteria for using the affirmative defense should be identical to the criteria for a malfunction 

in the malfunction definition. Any differences are arbitrary and capricious as the Agency has not 

cited any basis for the change that is supported by the record. 

 

 Other proposed criteria that must be met to avoid penalties are unduly ambiguous. For 

example, an owner and operator must ensure that “[a]ll possible steps were taken to minimize the 

impact of the excess emissions on ambient air quality, the environment, and human health.” 

Proposed 40 CFR §63.480(j)(4)(i)(E). It is unclear if this proposed provision requires an owner 

or operator to undertake all technically possible mitigation, or all economically feasible 

mitigation, or some third measure that appropriately limits “all” actions to mitigate the release. 

Moreover, it is unclear what an owner or operator could do to minimize”impacts” beyond 

minimizing emissions, which is already required under other criterion. 

Similarly, the requirement that an exceedance resulting from a malfunction must be 

reported within two days to qualify is ambiguous. Proposed 40 CFR §63.480(j)(4)(ii). At the 

start of an event, particularly a malfunction, it is often not possible to know whether the 

emissions will eventually exceed the limits. This is particularly true for emission standards that 

have long averaging periods. It would also not serve the Agency nor the regulated community 

well if EPA were to receive reports for many events which were later found not to have resulted 

in an exceedance. For these same reasons, a two-day notification is arbitrary and unreasonable. 

This requirement should be modified to allow the report to be made within 180 days of the 

exceedance. 

 It is arbitrary and unreasonable to require that the root cause analysis be submitted and 

corrective actions completed, along with all other affirmative defense information, within 180 

days of the start of the event. Proposed 40 CFR §63.480(j)(4)(ii). For significant events, it can 

take weeks to pull together a team of experts and to complete a root cause analysis. Long term 

corrective actions can require significant facility modifications that can take years to design and 

execute or procedural changes that can take months to safely implement. EPA should require 

that the root cause analysis be submitted as soon as practical after determining that there was an 

exceedance due to a malfunction. 

 
 6 

The unintended effects of the proposed treatment of malfunctions can be quite serious. 

For instance, in the case of an unexpected malfunction of the emission monitoring equipment an 

owner or operator may be unable to prove that an emission exceedance did not occur. This could 

be the case even though all operational and process-related parameters are within specification 

during the outage related to the monitors. In the absence of monitoring data, an analysis of the 

emissions might have to rely on the theoretical maximum rate that could be physically emitted 

rather than the actual emission rate. Further, if the higher assumed emission rate results in an 

exceedance being alleged by a regulatory agency it will likely not be possible to qualify under 

the nine point tests outlined for an affirmative defense. This is because criteria number six, an 

operator has to demonstrate that“[a]ll emissions monitoring and control systems were kept in 

operation if at all possible.” Yet, a malfunction to the monitoring equipment is precisely the 

reason that an emissions exceedance might be alleged. EPA should modify the SSM provision 

to explicitly preclude monitoring failures from resulting in assumed emission exceedances, and 

also not subject such malfunctions to the requirement of demonstrating the facility meet the 

criteria for an affirmative defense requirement. 

* * * * 

 

The proposal inappropriately favors reducing emissions over preventing injuries or 

fatalities. 

 Particularly disturbing are the limits placed on bypassing emissions equipment to prevent 

injuries to employees or other people. Penalties can be avoided for bypassing the emissions 

equipment only when it is “unavoidable to prevent loss of life, severe personal injury, or severe 

property damage.” Proposed 40 CFR §63.480(j)(4)(i)(D). Limiting this allowance only when it 

is “unavoidable to prevent loss of life, severe personal injury” is an inappropriate tradeoff 

given the low residual risk values calculated for these facilities. As EPA notes in presenting the 

results from their analysis, the lifetime cancer risk to the people with the highest exposures to the 

facility’s emissions are in the range of 1 in a million (10-6). Allowing a temporary emissions 

exceedance will therefore not result in a significantly higher health risk. Given the low residual 

risk levels, it should be acceptable to allow a temporary bypass of the emission equipment to 

avoid or prevent a significant possibility of injuries to workers and others. If a limitation is 

needed on what constitutes an “injury,” it is possible to utilize the OSHA classification for a 

“serious” versus “severe” injury. EPA should define an appropriate (lower) level of injury and 

require that the injury be likely avoided, as opposed to requiring the injury be unavoidable, to 

qualify for the affirmative defense. 

* * * * 

 The proposed approach does not properly weigh costs as required under the CAA. 

 The preamble to the proposed MACT standards acknowledges that EPA has not 

evaluated the costs of complying with the MACT standard under malfunction conditions. “EPA 

believes that a malfunction should not be viewed as a distinct operating mode, and, therefore, 

any emissions that occur during malfunctions do not need to be factored into development of 
 7 

CAA section 112(d) standards, which, once promulgated, apply at all times.” 75 Fed. Reg. at 

65074. Indeed, EPA flatly states, “it is reasonable to interpret CAA section 112(d) as not 

requiring EPA to account for malfunctions in setting emissions standards.” Id. EPA also cites 

Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (DC Circuit 1978) as supporting EPA’s decision to 

avoid evaluating the effects of malfunctions on the proposed MACT standards.2

 

 There are several contradictions contained within the Agency’s approach. First, EPA is 

neglecting to analyze the economic feasibility of meeting the MACT standards under 

malfunction conditions, but then requiring compliance with those very same standards during 

malfunctions. This approach results in proposed standards that have not been analyzed to 

determine if the costs associated with compliance are economically feasible. Without this cost 

and technical information, EPA cannot meet the clear statutory requirement in CAA section 

112(d) that the MACT standard be set at a level that the Administrator “taking into consideration 

the cost of achieving such emission reduction . . . determines is achievable.” Without the costs 

and technical data under malfunction conditions it is not possible to determine if compliance 

with the proposed standard is achievable. 

 The reference to the Weyerhaeuser v. Costle opinion is also unavailing because the 

current SSM provisions exempt malfunction conditions from the numerical MACT emission 

standard. Thus, at the time of the decision it was not necessary to address every malfunction or 

upset condition in the regulation. Indeed, the quote cited by the Agency, which states that “no 

general limit, individual permit, or even any upset provision can anticipate all upset situations,” 

supports IISRP’s position that the proposed regulations governing emissions during malfunctions 

are unworkable. The unanticipated and unpredictable nature of malfunctions, and the Agency’s 

cite to a D.C. Circuit opinion emphasizing that no regulation can address the broad set of 

possible malfunctions, demonstrate that the courts and the Agency have long recognized the 

futility of attempting to issue such a regulation. 

 The costs associated with complying with the proposed regulation are likely to be very 

high. This results from the need to meet the emission standards during the malfunction 

condition, or alternatively to meet the restrictive affirmative defenses. Since the possible nature 

and extent of a malfunction are not known in advance, the ability to reduce and eliminate the 

possibility of an emission exceedance depends on the ability to design, maintain, and operate a 

facility with multiple redundancies and virtually no defective components. Such a condition can 

only be met through upgrades to the design and frequent tests and replacement of components, 

all of which add significant costs. Given the low residual risks associated with the Group 1 

Polymers and Resins standards after this most recent round of MACT standard reviews, these 

additional costs would be found to be economically infeasible using the criteria and cost per ton 

figures developed by EPA. 

 

 

2

 “In the nature of things, no general limit, individual permit, or even any upset provision can anticipate all upset 

situations. After a certain point, the transgression of regulatory limits caused by ‘uncontrollable acts of third 

parties,’ such as strikes, sabotage, operator intoxication, or insanity, and a variety of other eventualities, must be 

a matter for the administrative exercise of case-by-case enforcement discretion, not for specification in advance 

by regulation.” Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (DC Circuit 1978). 
 8 

 In light of the high costs associated with the malfunction provisions, it is disturbing that 

EPA would maintain a provision that allows the Agency to impose additional costs to prevent 

malfunctions even when a malfunction meets the nine (9) separate tests to qualify under the 

affirmative defense provisions. Specifically, 40 CFR §63.480(j)(4)(i) states in part, “The 

affirmative defense shall not be available for claims for injunctive relief.” Thus, the Agency can 

dictate that additional costly measures (injunctive relief) be put in place to prevent malfunctions 

and the resulting emissions, even for malfunctions that “could not have been prevented through 

careful planning, proper design, or better operation and maintenance practices; and did not stem 

from any activity or event that could have been foreseen and avoided, or planned for.” It does 

not appear that this provision has any cost ceiling that prevents the Agency from demanding that 

changes be made to a facility to prevent all malfunctions that result in an emissions exceedance. 

Without a cost ceiling, the proposed provision will nullify and override the current cost analysis 

that EPA undertakes in setting the MACT standard. This provision should be eliminated since 

under EPA’s own proposed criteria the malfunctions that are being discussed “could not have 

been prevented.” Therefore these are malfunctions that cannot not be efficiently addressed 

through injunctive relief. 

 In conclusion, the proposed approach for addressing emissions during malfunctions is 

unworkable and technically unrealistic. As owners and operators attempt to comply, the net 

result will be an increase in compliance costs far out of proportion to any environmental or 

human health benefits, costs that will be far in excess of the control costs deemed reasonable 

during this very same MACT standards review process. And should a facility suffer an 

unexpected malfunction, their regulatory status and potential exposure to civil penalties will be 

subject to a set of arbitrary criteria that are ambiguous and subject to “after-the-fact” 

interpretation. EPA should re-propose criteria for addressing emissions during malfunctions that 

meet the requirements of Clean Air Act section 112(d) that such standards be “achievable” when 

“taking into consideration the cost of achieving such emission reductions.” 

* * * * 

Our next major concern is that no further rulemaking is required for the three source 

categories that apply to our industry (Butyl Rubber, Ethylene Propylene Rubber and 

Polychloroprene Rubber and therefore the June 30, 2011 final rule deadline is not applicable to 

these source categories. We have provided comments on this issue on EPA’s proposed consent 

decree with the Sierra Club ( EPA ID No. EPA-HQ-OGC-2010-058). ExxonMobil Chemical 

has provided extensive comments on two of these elastomers (Butyl and Ethylene Propylene) 

and the IISRP is in full support of their position. 

 EPA published the proposed consent decree referenced above in the Federal Register on 

July 14, 2010 (75 Fed. Reg. 40827). We submitted comments recommending that EPA 

modify the terms of the consent decree to exclude any further rulemaking for the Butyl 

Rubber and Ethylene Propylene Rubber source categories that are included in the current 

Group I Polymers and Resins rule. The basis for the request was as follows: 

 EPA, for four sources categories within the Group I Polymers and Resins category of 

sources, including Butyl Rubber and Ethylene Propylene Rubber, has already proposed and 
 9 

finalized 112(d)(6) and 112(f) determinations. See 73 Fed. Reg. 76,220 (Dec. 16,2008). 

EPA acknowledged the merit of these comments by amending the proposed consent decree 

when it moved to enter the decree on September 27, 2010. The proposed consent decree 

states that “the Group I Polymers and Resins NESHAP addresses nine different categories . . 

. . [t]he obligations in this paragraph apply only to the following five Group I Polymers and 

Resins categories: Epicholorohydrin Elastomers Production; HypalonTM Production; Nitrile 

Butadiene Rubber Production; Polybutadiene Rubber Production; and Styrene Butadiene 

Rubber and Latex Production.” Footnote 4 of the Proposed Consent Decree, Sierra Club v. 

Jackson, No. 09-cv-00152. 

 EPA’s proposal discussing these source categories states that “[t]these four categories 

were determined to be “low-risk,” as the maximum lifetime individual cancer risks were less 

than 1-in-1-million, and there were no other health concerns of significance. Therefore, we 

determined that conducting additional risk analyses for these categories was not warranted. 

We are not re-opening the RTR [Residual Risk and Technology Review] in this notice for 

these four source categories.” 75 FR at 65075 

 Despite this recent finding less than two years ago, EPA nonetheless is embarking on yet 

another rulemaking despite acknowledging its recently completed work found no significant 

residual risk. The purported basis for yet again conducting a new emission standard setting 

process is the Agency’s identification “of significant emission sources for which MACT 

standards were not previously developed.” This seems unlikely because the facilities at issue 

have not been modified in any significant manner that would increase emissions. 

Further, as noted in the ExxonMobil comments, EPA lacks the legal authority to establish 

new limits. Specifically, EPA is without authority to impose new standards under §§ 112(d)(2) 

and (3) for the Polymers and Resins 1 source categories since a MACT standard already has been 

promulgated – § 112(d)(6) provides the Agency’s only authority to adjust existing MACT 

standards. 

Once EPA establishes a MACT standard for a particular source category, the Agency has 

the authority under §112(d)(6) to “review and revise as necessary (taking into account 

developments in practices, processes, and control technologies), emissions standards 

promulgated under this section no less often than every 8 years.” In other words, EPA does not 

have unfettered discretion to revisit a prior MACT determination once that determination has 

been issued. Rather, EPA may revise a prior determination only “as necessary” according to 

explicit statutory criteria. Cf. New Jersey v. EPA, 517 F.3d 574, 582 (D.C. Cir. 2008) (“Thus, 

EPA can point to no persuasive evidence suggesting that section 112(c)(9)’s plain text is 

ambiguous. It is therefore bound by section 112(c)(9) because “for EPA to avoid a literal 

interpretation at Chevron step one, it must show either that, as a matter of historical fact, 

Congress did not mean what it appears to have said, or that, as a matter of logic and statutory 

structure, it almost surely could not have meant it,” Engine Mfrs. Ass’n v. EPA, 88 F.3d 1075, 

1089 (D.C. Cir. 1996), showings EPA has failed to make.”). 

In this proposal, EPA explains that, “For eight source categories subject to three of the 

MACT standards, we identified significant emission sources within the categories for which 
 10 

standards were not previously developed” and that, “We are proposing MACT standards for 

these emission sources pursuant to CAA section 112(d)(2) and (3)." 75 Fed. Reg. at 65074. This 

explanation makes it clear that EPA is not invoking §112(d)(6) as the authority for the new 

proposed standards – indeed, the preamble provides no analysis of “developments in practices, 

processes, and control technologies” to justify the proposed standards, as would be required if 

EPA were relying on §112(d)(6). And, there is no mention of §112(d)(6) in relation to the 

proposed new standards. Instead, the Agency is invoking §§112(d)(2) and (3) directly, as if a 

MACT standard for these sources categories does not already exist. 

As explained above, once EPA makes a MACT determination for a particular category, 

§112(d)(6) provides the only authority for the Agency to later review and possibly revise the 

determination. Section 112(d)(6) expressly authorizes EPA to review existing determinations 

and provides specific criteria to guide and constrain the review. The existence of this express 

authority forecloses the Agency’s ability to directly invoke §§112(d)(2) and (3) for a given 

source category when a MACT determination has already been issued for the source category. 

Notably, even if the Agency had invoked §112(d)(6) as authority for revising the existing 

P&R1 rule, it still would not have authority to regulate emissions points for which standards 

were not established in the original rulemaking. The original MACT determinations may be 

revised only “as necessary (taking into account developments in practices, processes, and control 

technologies).” Perceived “gaps” in the original MACT determinations are not “practices, 

processes, and control technologies” that are properly within the scope of a §112(d)(6) review. 

In any event, it is not a reasonable exercise of authority to establish new emissions 

limitations under an existing MACT standards when there is no significant risk associated with 

emissions from sources in the given source category. 

EPA asserts in the proposed rule the proposition that standards must be established for 

“significant emissions points” not currently regulated under existing MACT standards – even in 

circumstances where the Agency has determined that the existing MACT standard protects 

health and the environment with an ample margin of safety. Establishing new standards under 

these circumstances is patently unreasonable and cannot be justified under §112(d)(6). 

In the case of the P&R1 NESHAP, EPA explains that for the Epichlorohydrin source 

category and based on a detailed assessment of risk to health and the environment due to HAP 

emissions from these source categories, “we continue to propose that the current MACT standard 

provides an ample margin of safety to protect public health and the environment, and we are 

proposing to re-adopt the existing MACT standard to satisfy section 112(f) of the CAA.” 75 

Fed. Reg. at 65098. EPA previously had made this determination for both the Butyl Rubber and 

EPR source categories and yet in this rulemaking the Agency proposes new emission 

limitations/controls for Butyl Rubber and EPR front-end process vents and Butyl Rubber backend process vents. 73 Fed. Reg. 76620. 

As explained above, EPA has no direct authority under §§112(d)(2) and (3) to create new 

limits in source categories for which a MACT standard already has been promulgated. But, even 

if EPA had invoked §112(d)(6) as authority for adopting the new standard for back end process 
 11 

operations, such a standard would not be justified because EPA’s own analysis demonstrates that 

the existing MACT standard provides an ample margin of safety to health and the environment. 

In fact, EPA plainly admits for the Epichlorohydrin source category that “the MACT standard, 

prior to the implementation of the proposed emission limitation to the back-end process 

operations discussed in this section, provides an ample margin of safety to protect public health.” 

75 Fed. Reg. 65099. 

In the case of the Butyl Rubber and EPR source categories, EPA’s residual risk evaluation, 

73 Fed. Reg 76220 (Dec. 16, 2008), not only found that the public is protected with an ample 

margin of safety, but that the risks are so low that they would not meet EPA’s criteria for risk 

reduction (i.e., reducing the number of people exposed to an above one in one million cancer 

risk). In fact, as EPA states in the residual risk no further action notice, for these source 

categories “No HAP that are known, probable, or possible human carcinogens are emitted from 

sources in the category.” Id. at 76225, Table 4, Note 6. A similar finding is reported relative to 

EPA hazard index of concern (HI 1.0). EPA concluded the maximum hazard index for the EPR 

source category is 0.5 (due to n-hexane) and 0.2 for the butyl source category (due to methyl 

chloride). Id. at 76225, Table 4. 

In these circumstances, it is patently unreasonable for EPA to regulate beyond the point 

that the standard has been found to already provide an ample margin of safety. This is regulation 

for the sake of regulation and, as such, contradicts Congress’s clear intent that an ample margin 

of safety is an appropriate stopping point for emissions limitations under §112.3 

We fully support the Exxonmobil position regarding beyond the floor controls. EPA 

already made the decision that beyond the floor controls for continuous front-end process vents 

were not cost-effective in the 1996 rulemaking. EPA has no authority and no grounds to perform 

a second section 112(d)(2) analysis for these emission points. 

In the 1996 final rule, EPA was aware that halogenated vent streams were vented to a flare 

or boiler at Butyl Rubber, Halobutyl Rubber, and EPR facilities. While the flare or boiler 

provided control for the organic HAP, methyl chloride, it was well-known that hydrogen 

chloride would be generated by the combustion process. After considering this information, 

EPA determined that the floor for control of this organic HAP was combustion in a flare or 

boiler and that beyond-the-floor control of the HCl generated in the combustion was not costeffective and not justified. EPA explained: 

Only one existing facility was identified in each of the Halobutyl and the Butyl rubber 

subcategories. At both of these facilities, halogenated vent streams were vented to a 

 

3

 EPA also explains in the context of the proposed new limit for back-end process operations that, because the 

existing MACT standard already provides an ample margin of safety, “we do not believe it will be necessary to 

conduct another residual risk review under CAA section 112(f) for this source category 8 years following 

promulgation of new back-end process limitations, merely due to the addition of this new MACT requirement.” 

Implicit in this statement is the suggestion that a residual risk review under §112(f) may be needed for new 

emissions limits that are established for existing MACT standards. As with setting MACT standards in the first 

instance, §112(f) provides a one-time opportunity for conducting a residual risk review of a MACT standard. 

There is no basis under the law for the suggestion that a revision to an existing MACT standard triggers the 

need for another §112(f) residual risk review. Indeed, the proposal provides no explanation whatsoever as to 

why such a subsequent review could be required under the law. 
 12 

flare and/or boiler. Since both of these subcategories were single-facility 

subcategories, the MACT floor was determined to be the existing level of control. 

The EPA examined the impacts of requiring halogenated vent streams at the 

Halobutyl and Butyl rubber facilities to comply with the proposed requirements for 

all other elastomer subcategories (i.e, the HON-level of control). The EPA concluded 

that the costs associated with this level of control were not reasonable, given the 

associated emission reduction. Therefore, the proposed regulation allowed 

halogenated streams at Halobutyl and Butyl rubber facilities that were routed to a 

flare or boiler prior to proposal to continue to be controlled with these combustion 

devices, without additional control for the resulting halides. ... 

...[T]he EPA concluded that four of the five EPR facilities have halogenated streams 

that are routed to either a boiler or flare. For this reason, the EPA has determined that 

the floor for EPR is the existing level of control for these halogenated vent streams. In 

addition, as with Halobutyl and Butyl rubber, the EPA does not believe that it would 

be cost-effective to require new incinerators and scrubbers to be installed at these 

facilities, when the only net emission reduction would be the reduction of the 

hydrochloric acid, since the reduction of the halogenated organic compound in the 

incinerator would be the same as was already being achieved in the boiler or flare. 

However, as noted above, sufficient stream-specific information was not available to 

conduct this analysis. Therefore, the final rule has been changed to extend the 

exemption for existing halogenated streams routed to a boiler or flare to EPR 

producers. Further, the final rule specifies that this exemption does not apply to new 

sources. 61 Fed. Reg. at 46919. 

 This passage from the 1996 rulemaking clearly demonstrates that EPA has conducted a 

complete analysis under sections 112(d)(2) and (d)(3). Therefore, EPA met its obligation to set 

an emissions standard for these HAPs in these categories and subcategories. EPA’s only 

remaining authority to revisit the rulemaking, in the absence of a timely legal challenge to this 

particular standard in the P&R1 rule, which was not lodged, are the 8-year technology review 

and the one-time residual risk review. Those reviews, too, were completed and final action 

noticed at 73 Fed. Reg. 76220, again without challenge. Even as part of a periodic technology 

review, EPA is not required, and we believe not allowed, to “start from scratch.” NRDC v. EPA, 

529 F.3d 1077, 1084 (D.C. Cir. 2008). 

 The 1996 rulemaking also undercuts EPA’s claimed basis for revisiting the standard – the 

“absence of a standard for a significant emissions source.” 75 Fed. Reg. at 65108-65109. EPA 

performed the required standard-setting analysis under section 112(d)(2) consistent with D.C. 

Circuit precedent. This is not a case of “no control floors” or source “exemptions,” which the 

D.C. Circuit has held to be unlawful under section 112. Nat’l Lime Ass’n v. EPA, 233 F.3d 625 

(D.C. Cir. 2000); Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008). In this case, EPA 

determined that the existing level of control for the halogenated compounds – a flare or boiler – 

was all that was required, and the further reduction in HCl was not cost-effective. The 

“exemption” in the 1996 rule is from “HON-level” controls, not all control. 
 13 

 We are not aware of any prior MACT rule where EPA, in the absence of a court decision, 

rule vacatur, or settlement agreement, revisited a beyond-the-floor analysis. EPA should not do 

so in this rule. 

* * * * 

Our final concern is that. EPA must include variability in the floor calculation In

establishing the emission limits EPA did not consider variability, which is appropriate in setting 

emission standards. It is acceptable and expected for EPA to consider emission levels associated 

with normally anticipated and recurring operating conditions, and decisions of the D.C. Circuit 

acknowledge that data from more adverse operating conditions can inform the basis of the 

standard. Thus, EPA should establish a standard that MACT floor units can meet if operating 

“under the most adverse circumstances which can reasonably be expected to recur.” [Sierra 

Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999), quoting National Lime Ass’n v. EPA, 627 F.2d 

416, 431 n.46 (D.C. Cir. 1980)] 

Indeed, in that 1999 Sierra Club decision, the court emphasized: 

EPA would be justified in setting the floors at a level that is a reasonable estimate of the 

performance of the ‘best controlled similar unit’ under the worst reasonably foreseeable 

circumstances ....” [Sierra Club v. EPA, 167 F.3d at 665. Accord Cement Kiln 

Recycling Coalition v. EPA, 255 F.3d 855, 863 (D.C. Cir. 2001)] 

In the Cement Kiln case, EPA argued that it is acceptable for it to consider the range of 

emissions from the best performing sources and that test results at more adverse conditions “’are 

more helpful than normal operating data would be in estimating performance under a variety of 

conditions and thus in helping to assure that properly designed and operated sources can achieve 

the standard.’” [Cement Kiln, 255 F.3d at 867 (quoting EPA)] The court affirmed this 

interpretation. [Id] Further, the D.C. Circuit in its 2004 decision in Mossville Environmental 

Action Now v. EPA held that floors may legitimately account for variability because “each 

[source] must meet the [specified] standard every day and under all operating conditions.” [F.3d 

1232, 1242, as quoted in Sierra Club v. EPA, 479 F.3d 875, 882 (D.C. Cir. 2007) (Brick 

MACT)] 

In this proposal, EPA only used one data point, the annual emissions level and from one 

calendar year (2009) for units in the Butyl, Nitrile and Epichlorohydrin subcategories, and did 

not look at statistical variation over time. And if EPA revisits the subcategories then EPA should 

also consider other factors such as the variability in source design and operation within a 

subcategory. 

 

There are a number of factors that contribute to the variability of emissions on an annual 

emissions per unit of production basis. These factors include production itself as not all 

emissions (e.g. fugitives) are a function of production. Other factors include grade slate changes, 

operating conditions, process reliability and control device reliability/service factor. 

 
 14 

 Respectfully submitted, 

sent via email 

James L. McGraw 

Managing Director and CEO 

International Institute of Synthetic Rubber Manufacturers (IISRP) 

cc: Mr. Scott Throwe 

 Compliance Assessment and Media Programs Division (Mail Code: 2223A) 

 Office of Compliance 

 U.S. Environmental Protection Agency 

 1200 Pennsylvania Avenue, N.W. 

 Washington, DC 20460 

 Mr. Randy McDonald 

 Sector Policies and Programs Division (E143-01) 

 Office of Air Quality Planning and Standards 

 U.S. Environmental Protection Agency 

 Research Triangle Park, NC 27711 

 Attn: Desk Officer for EPA 

 Office of Information and Regulatory Affairs 

 Office of Management and Budget (OMB) 

 725 17th Street, NW. 

 Washington, DC 20503