MEMORANDUM 

Date: February 15, 2011 

Subject: Summary of EPA Meeting with ExxonMobil Representatives to Discuss the Polymers and 

Resins I Portion of the 2010 RTR Proposal/Supplemental Proposal 

From: Lesley Stobert, EC/R Incorporated 

To: Nick Parsons, EPA/OAQPS/SPPD/CCG

The purpose of this memorandum is to summarize the meeting held on February 14, 2011, between 

representatives of the Environmental Protection Agency (EPA) and ExxonMobil representatives. The 

topic of this call was the proposed revisions to the National Emission Standards for Hazardous Air 

Pollutants (NESHAP) for Polymers and Resins I (40 CFR 63, subpart U), specifically for the of 

Butyl Rubber, Halobutyl Rubber, and Ethylene Propylene Rubber Production source categories. 

PARTICIPANTS 

Robert Berg, ExxonMobil

Bob Morehouse, ExxonMobil

Diane Otto, ExxonMobil

David Pultz, ExxonMobil

Wayne Sadik, ExxonMobil 

Norm Morrow, Fresh Air Consulting

K.C. Hustvedt, U.S. Environmental Protection Agency 

Penny Lassiter, U.S. Environmental Protection Agency 

Nick Parsons, U.S. Environmental Protection Agency

Brenda Shine, U.S. Environmental Protection Agency

Phil Norwood, EC/R Incorporated 

Lesley Stobert, EC/R Incorporated

SUMMARY OF CONVERSATION 

The purpose of the meeting was to discuss ExxonMobil’s comments on the October 21, 2010 

proposal/supplemental proposal for several source categories, including the Butyl Rubber, Halobutyl 

Rubber, and Ethylene Propylene Rubber Production source categories of the Polymers and Resins I 

MACT (75 FR 65068). 

ExxonMobil representatives presented their concerns with the proposed requirements for the 

Butyl Rubber, Halobutyl Rubber, and Ethylene Propylene Rubber Production source categories. A 

copy of the presentation is attached in an Appendix to this memorandum. Bob Morehouse stated that 

the key issues the company was concerned with were the cost effectiveness of the proposed controls 

and allowance for process variability in the setting of numerical emission limits. Also a concern was 

the possible inability of the facilities to meet the emission limits during periods of startup and 

shutdown. The ExxonMobil representatives stated an intention to provide EPA with additional 

information regarding work practices that would limit emissions during these periods.
Appendix

ExxonMobil Presentation
Summary of ExxonMobil Comments on 

Proposed Rulemaking

NESHAP for Group I Polymers and Re

October 21, 2010 (75 FR 65068)

Butyl Rubber and Ethylene Propylene R

Source Categories

February 14, 2011
Summary of ExxonMobil Comments

• Since there is no consent decree deadline to finalize a rule for the Butyl Rubber and E

Propylene Rubber source categories, EPA should take the appropriate time to thoroug

comments submitted and reassess the cost-effectiveness determinations

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

that source emissions are at an acceptable risk level, is not sound regulatory policy

- This proposal is inconsistent with the EPA Administrator’s key principles which include obtaining 

with cost-effective controls

- This proposal is inconsistent with Executive Order 12866 of September 30, 1993, which was rece

EO 13563 of January 11, 2011, that each Agency must “propose or adopt a regulation only upon 

determination that its benefits justify its costs”

• EPA lacks authority to impose new standards under CAA § 112(d)(2) and (d)(3) for s

categories for which a (d)(2) and (d)(3) standard has already been promulgated

- EPA made the decision that beyond-the-floor controls were not cost-effective in the 1996 rulemak

has no authority or basis to perform a second CAA § 11 2(d)(2) analysis and has provided no rati

the original analysis is deficient or no longer applicable

• The proposed back-end emission limits for the Butyl Rubber source category require f

modification to reflect actual emissions performance and variability

• The proposed beyond-the-floor controls for front-end and back-end process vents are 

effective; EPA significantly underestimated the cost of controls

• EPA does not have the authority to combine source categories in order to justify contro

assumed shared control system is inconsistent with maintaining facility operating flexib

controls would be implemented

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

differences

2
Summary of ExxonMobil Comments (Cont’d)

• Regular maintenance of Regenerative Thermal Oxidizers (RTO5) is required to achiev

HAP destruction (the removal percentage assumed by the proposal)

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

controls (Administrator has authority to add the 4th year)

• The D.C. Circuit SSM decision does not require the imposition of a single emission sta

at all times; EPA should propose a separate emission limit or apply work practice stan

periods of SSM

• The proposed affirmative defense is unreasonable and impracticable

• EPAs position that it was not necessary to revisit the residual risk and technology rev

Rubber and Ethylene Propylene Rubber source categories is appropriate

- No cancer risk identified; hazard index <1

- No new developments in control technology or work practices

3
Background on Rulemaking

• Original MACT for Polymers and Resins I (P&R 1) finalized September 5, 1996

- Two source categories impact ExxonMobil: Butyl Rubber (BR) and Ethylene Propylene Rubber (

- The Butyl Rubber source category was subcategorized into Butyl Rubber and Halobutyl Rubber 

- The original rulemaking considered floor and beyond-the-floor options

+ Emission limits were established for organic hazardous air pollutants (HAPs) from BR and EP

process vents and EPR back-end vents

+ Beyond-the-floor analyses showed organic HAP limits not cost-effective for BR back-end pro

HCI from any vents controlled by combustion

• Brick MACT court decision: March 13, 2007

• Residual risk and technology review completed for four P&R 1 source categories (incl

EPR); finalized December 16, 2008

- Risk acceptable and no further controls required

- No legal challenges to final rule

• Startup/Shutdown/Malfunction (SSM) D.C. Circuit court decision: December 19,2008

• NRDC/Sierra Club petition for rulemaking on MACT standard setting: January 14, 200

• EPA finalized rulemaking schedule in consent decree: September 27, 2010

- Does not include BR and EPR source categories

• EPA P&R 1 proposal issued October 21, 2010

- Identifies some previously regulated emission points as “Significant Emission Points Not Previou

- Proposes additional emission limits and determines that some beyond-the-floor controls, previou

1996, are now cost-effective and required

4
Overview of ExxonMobil Operations

• ExxonMobil facilities subject to the proposed rule:

- Baton Rouge Chemical Plant Halobutyl and EPR units

- Baton Rouge Plastics Plant “Line G” EPR unit

- Baytown Chemical Plant Butyl unit

• Baton Rouge Halobutyl Unit

__________________

Rubber

Product

___ __

I

Front-End Vents

(Flare)

I

..-

iecoverv

Raw Material

Back-End Vents

Residual to Atmosphere

I

catalyst

EEE

[Iii’

I:TtIi

LJJ iiJ

I__ a L1I

Iii

Ive

Fove

BRCP Halobutyl Production Facility

5
Butyl Rubber Source CategorylSubcategories

• The Butyl Rubber source category subcategories have changed since subpart U was 

- The 1996 rulemaking recognized the significant differences between the ExxonMobil Baton Rou

Butyl Rubber facilities and therefore subdivided the Butyl Rubber source category into “Halobuty

subcategories, reflecting the Baton Rouge and Baytown operations, respectively

- Halobutyl elastomers incorporate chlorine or bromine into their molecular structures

- In the last 15 years there have been projects to adjust product mix, provide operating flexibility, 

process efficiency at Baytown; that unit now produces more Halobutyl elastomers than Butyl ela

• However, there remain basic process and emission differences between the two sites 

continuing segregation into two separate subcategories --see ExxonMobil CBI letter

• Revisions to 40 CFR subpart U are needed to reflect the current situation

- The subcategory descriptions should be modified to distinguish between Halobutyl-only productio

product production

- The primary product determination should only be applied to facilities at the source category leve

subcategory level

• Combining the two ExxonMobil Butyl units into the same subcategory (i.e., Halobutyl) 

outgrowth of the proposal and would require a new beyond-the-floor analysis and a n

- EPA proposed beyond-the-floor organic HAP back-end controls for Baytown and not Baton Rou

two units into one subcategory would necessitate further analysis and a new proposal

- Based on EPA estimates the combined subcategory analysis would indicate that back-end contr

justified

6
Applicability

• EPA should not finalize the proposal to require halogen controls for BR and EPR Gro

front-end process vents

- No discussion or analysis was provided to support/justify this requirement

- Halogen removal requirements are only associated with process vents that are combusted to com

organic HAP removal requirement, which by definition doesn’t apply to Group 2 vents and are no

applied

• EPA should clarify the definition of back-end process to avoid confusion and to remov

that are already regulated under subpart U (e.g., surge control vessels are already re

also appear to be covered by the back-end definition)

• The proposed BR back-end emission limits, and compliance demonstrations, should 

mass of material going to the back-end, not on finished product

7
Floor Analysis and Emission StandardsNariabi

• EPA is without authority to impose new standards under § 1 12(d)(2) and (d)(3) for th

categories since a MACT standard already has been promulgated; § 1 12(d)(6) provid

only authority to adjust existing MACT standards

• EPA must include variability in establishing back-end emission limitations

- The proposed standards were based on only one year of emission data; the D.C. Circuit acknow

from more adverse operating conditions can inform the basis of a standard

- Additional data was provided in the ExxonMobil CBI letter to support including variability; the dat

emissions per unit of production has varied by 43%

- The year reported (2006) for Baton Rouge Halobutyl was among the lowest in the time period; us

data would mean that the site could not have met the proposed limit in four of the last five years; 

would not represent the current floor or the future capability of the unit

- Factors that impact emissions include production, grade slate, operating and weather conditions, 

and control device/service factor

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

maintain maximum organic HAP destruction

- RTOs require regular maintenance, necessitating periodic bypassing (allowed under state rules/p

- The Agency should provide for up to 240 hours/year of RTO maintenance; either the potential em

associated with the bypass can be incorporated into the annual average emission limit or bypasse

excluded from the compliance demonstration

- EPA will also need to clarify that bypasses of back-end control equipment are allowed as long as 

month back-end emission limit is met

8
Butyl Rubber Back-end Floor Analysis Summary

n-hexane, Tons

Baytown Butyl Baton Rouge Halobutyl

Basis for floor 43.01 59.98

Variability adjustment 18.49 25.79

(43% minimum)

Floor emission limit 61.5 85.8

Note: Final production-based limit should be based on production data included in ExxonMobil CBI lette

• Should the Agency impose back-end emission limits, the limits should include at le

adjustment for variability and include an equivalent maintenance allowance to that 

to be needed for the existing RTOs for any additional emissions that will require ne

9
Beyond-the-Floor Decisions

• EPA already made the decision that beyond the floor halogen controls for continuou

process vents were not cost-effective in the 1996 rulemaking; EPA has no authority 

to perform a second § 112(d)(2) analysis for these emission points

- In the 1996 final rule EPA noted:

“The EPA examined the impacts of requiring halogenated vent streams at the Halobutyl and 

facilities to comply with the proposed requirements for all other elastomer subcategories (i.e

control). The EPA concluded that the costs associated with this level of control were not rea

associated emission reduction. Therefore, the proposed regulation allowed halogenated stre

and Butyl rubber facilities that were routed to a flare or boiler prior to proposal to continue to 

these combustion devices, without additional control for the resulting halides. ..“

- A comparable analysis was done in 1996 for the EPR source category

• EPA’s beyond-the-floor determination for halogenated front-end process vents at the 

Baton Rouge EPR Unit that is based on sharing controls with the co-located Halobuty

EPA’s legal authority

- EPR and the Halobutyl unit are in different source categories; CAA § 112(d) requires the develo

regulations by source category or subcategory

- Halogenated front-end process vent controls for the EPR unit are not justified even on EPA’s co

• EPA’s analysis based on sharing controls is inconsistent with maintaining business o

flexibility and how controls would be implemented

- The two distinct businesses and the need to be able to maintain the controls does not support a 

10
Beyond-the-Floor Decisions (cont’d)

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

EPR, and Baytown Butyl Rubber are not cost-effective and should not be finalized; th

effectiveness for the proposed halogenated continuous front-end process vent contro

ranges from $21,000/ton to $80,000/ton of HCI

• The proposed back-end beyond-the-floor controls for Baton Rouge Halobutyl and Bay

Rubber are not cost-effective and should not be finalized; the cost-effectiveness for th

back-end control requirements is over $70,000/ton of organic HAP

11
ExxonMobil Front-end Control Cost Analysis

Capital Annual HCI CostCost Cost Reductions effectiveness

Process $K1 $K TonslYear $ITon Comments

Baton 9,600 1,220 23.8 51,100

Rouge EPR

Baton 12,400 1,570 76.0 20,700

Rouge

H a lobutyl

Baton 13,300 1,690 99.8 16,900 Not practical/

Rouge legal case

Combined

Baytown 16,200 1,960 24.5 80,100

B utyl

1 Includes Project Services costs

Note: Annual cost includes capital cost times a capital recovery factor of 0.1098 (as proposed) 

costs

12
Annual

Cost

$K

2,450

n-hexane

Reductions

TonslYear

33.9

Costeffectiveness

$ITon

72,300

Back-end Control Cost Analysis ExxonMobil

Capital

Cost

$K1

18,100

Process

Baton

Rouge

Halo b utyl

Baytown 12,500 1,530 20.2 75,600

Butyl

1 Includes Project Services costs

Note: Annual cost includes capital cost times a capital recovery factor of 0.1098 (as proposed) plu

13
Development of Proposal Cost Estimates

• ExxonMobil utilizes a structured process to develop capital projects, including cost est

- Common framework across company

- Gate process focuses on a broad range of project elements employed with go/no go decisions

- Exxon Mobil estimating tools, methods and data in existence and continuously improved for over 

- ExxonMobil global cost databases are updated twice a year based on actual purchase orders, c

experience and contractor and subcontractor surveys

• Review of proposal and initiation of project development triggered significant resource 

- Cost estimators worked closely with site technical contacts to develop project basis, including eq

stream characterizations, structural modifications, project scope

- Cost analysis included site visits and review of support systems (e.g. wastewater, electricity) and

access/congestion issues; not normally done for initial project estimate

• Estimate development

- Major and specialty equipment budget quotes received from third party contractors for control eq

ductwork

- Other direct cost items (e.g., pumps, piping, instrumentation, foundations) estimated using Exxo

methods

- Project management costs based on ExxonMobil experience; contingency added consistent with 

projects in the development stage

14
Regenerative Thermal Oxidizer Project Costs

• ExxonMobil has experience in the cost of installation and operation of regenerative the

at many locations

• Actual project cost data supports ExxonMobil 7scurrent control cost estimates and high

EPA’s estimates are significantly understated

• Past projects reflect costs in the $7M to $14M range (excluding project services costs)

Summary of Actual Project Capital Costs

Year of Airflow VOC Capital

Project Installation (kscfm) (Iblhr) 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 / 60 287.0 12.1

2005

Note: M = million; dollars converted to 2013 Baytown, Texas location

15
Technology Selection

n-hexane emissions control

• n-hexane streams are high air volume, low VOC concentration, and high moisture con

quantities of acid forming compounds

• Control technology of choice is a regenerative thermal oxidizer; this technology has k

- High destruction and energy efficiency for dilute streams

- Low NOx emissions for ozone non-attainment compliance

- All surfaces contacting gas stream can be made corrosion resistant

Methyl Chloride/HCI emissions control

• MeCI streams are low volume, high MeCl concentration, and need air addition to ensu

• Control technology of choice is a recuperative thermal oxidizer with a quench and acid 

this technology has key advantages

- High destruction and energy efficiency for concentrated streams

- All surfaces contacting gas stream can be made corrosion resistant

16
Major Deficiencies with EPA Control Cost Estima

• EPA’s capital and operating cost estimates for the controls proposed have major defi

significantly underestimate the expected costs

• EPA costs are based on a new plant with no retrofit considerations included

• Retrofit issues at the ExxonMobil facilities include:

- Oxidizer location and associated ducting (and structural steel supports for overhead locations)

- Inefficiencies and added costs associated with working in an operating process unit and in confin

- Minimizing process outages for tying-in and constructing the new facilities

- Dismantling of some existing facilities to accommodate installation of new facilities

- Limited utilities availability

- Extensive additional detailed engineering associated with retrofits

• ExxonMobil estimate based on efficient/appropriate regenerative thermal oxidizers for 

process vents

• EPA estimate didn’t include the extensive ducting and other auxiliary equipment, inclu

storage drum and heat exchangers

• EPA used a total capital investment factor of only 1.25 to 2.20 applied to purchased eq

determine total capital investment; experience indicates a ratio of 4 to 5 is appropriate

• EPA’s indirect costs for engineering, construction supervision, scaffolding, construction 

and other field expenses are significantly underestimated

17
Compliance Time

• For this proposal, EPA should provide 4 years to comply with emission limits that requ

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

rule (pursuant to CAA § 1 12(i)(3)(B) and 40 CFR 63.6(i))

- Projects, if required in a final rule, will involve a complex retrofitting of control equipment into exis

- Boiler/Process Heater MACT and utility rules will trigger significant demand for combustion engin

and construction resources

• EPA should allow four years for compliance with the proposed BR source category ba

emission limits if variability and maintenance of the existing RTOs are not fully addres

- The proposed back-end emission limit was based on the emissions data provided for a single yea

assumption that no capital investment is required

- The proposal did not allow for variability; without the appropriate recognition of variability in most 

limit will be exceeded, necessitating capital investment

- Proposal does not currently consider the state permit conditions available to the sites to allow for 

the existing RTOs, effectively tightening the standard beyond the floor

- Loss of SSM provisions

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

proposed back-end emission limits, the first compliance demonstration is due two year

following the date of the final rule

- As proposed, compliance is required beginning one year after rule publication

- Data collection begins in the 13th month

- With annual emission limit, compliance is first determined after the 241 month

18
Compliance Time (cont’d)

• EPA should clarify that the compliance date related to removal of the Startup? Shutdow

provisions is also four years

- SSM emissions not included in 1996 standards development

- Time needed to invest capital to improve or add controls and/or to modify work practices

19
StartuplShutdownlMalfunction Provisions

• EPA has misread Sierra Club v. EPA; EPA has the authority to apply a different emiss

during SSM events than applies during normal operations

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

SSM to appropriately recognize the operating and emission differences during these p

- This could include the development and implementation of SSM plans

• The proposed affirmative defense is not an appropriate substitute for setting emission 

malfunction periods

- An affirmative defense, even if asserted and acceptable, still means that the source may be cons

of the standards with the associated legal vulnerability

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

- Many aspects of the proposed affirmative defense make it unavailable as a practical matter for m

malfunctions; for example, how will enforcement authority determine whether ‘proper design” or 

and maintenance practices” could have prevented a malfunction or whether a source took “all po

minimize the impact of the excess emissions?

• Detailed recommendations on the affirmative defense provisions are included in the c

package

20
Maintenance Provisions

• Maintenance of back-end RTO’s was discussed previously

• Front-end control device maintenance should also be addressed

- Thermal oxidizer/halogen scrubber systems have lower service factors than the process unit, fla

combustion devices because of their increased susceptibility to halogen corrosion and to pluggin

- An allowance for some thermal oxidizer/halogen scrubber maintenance is allowable as long as i

considered in the beyond-the-floor evaluation

- Recommend EPA allow up to 240 hours per year of thermal oxidizer/halogen scrubber outage, a

front-end process vents are routed to a flare or other combustion device during that outage

- Allowance would have a small impact on post control emissions while saving significant producti

and emissions by avoiding unit shutdowns while conducting maintenance on these control devic

• Maintenance of surge control vessels controlled with non-water condensers

- Condensers commonly are used to control storage vessel and surge control vessel emissions in 

operations (material recovery, cost-effective)

- Storage vessels have planned routine maintenance provisions providing for up to 240 hours of c

outage

- Loss of SSM provisions creates issue for surge control vessels when refrigeration system is shut 

maintenance; potential need for installation of alternative control (e.g. combustion) that will result 

material and increased emissions

- Recommend, similar to HON and MON rule, to allow use of the storage vessel control provisions 

vessels

21
Appendix

- Baytown Butyl Rubber Unit Back-end Emissions

- Baton Rouge Butyl Rubber Unit Back-end Emissions

- Baytown Butyl Rubber Front-end Emissions

- Baton Rouge Butyl Rubber Front-end Emissions

- Baton Rouge EPR Front-end Emissions

- Potential Back-end Emission Reductions

- EPA Analysis of Cost-Effectiveness for Proposed Front-end HCI Control

- EPA Analysis of Cost-Effectiveness for Proposed Back-end Control

- ExxonMobil Operating Costs

- EPA Policy on Residual Risk and Technology Reviews

22
Baytown Butyl Rubber Unit (Butyl Subcategory)

2009 Back-end Emissions, n-hexane

Emissions

Emission IDlDescription 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 1 1 .27 Emission limit should be

(including surge control vessel based on emissions not

emissions) in BPBFinish and already subject to subpart

RGTO U requirements

Basis for floor 43.01 Prior to including variability

Less emissions already 17.24 Emissions from existing

controlled RTO

Emissions basis for beyond- 25.77

the-floor analysis (Note 1)

Note 1: This item includes emissions not routed to the RTO and emissions associated with main

RTO as discussed in the comment package

23
Baton Rouge Butyl Rubber Unit (HaobutyI Subcategory)

2006 Back-end Emissions, n-hexane

Emissions,

Emission IDlDescription TonslYear 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 18.32 Emissions from existing RTO

controlled

Emissions basis for beyond- 41.66

the-floor analysis (Note 1)

Note 1: This item includes emissions not routed to the RTO and emissions associated with 

existing RTO as discussed in the comment package

24
Baytown Butyl Rubber Front-end

2009 Emissions, HCI

Emission Emissions

ID/Description tons/year Comments

FS12 (flare stack) 30.09 Reported to EPA in ICR

Less emissions not from 5.39 Loading rack, exchanger

continuous process depressurization, safety bypass

vents

Basis for beyond-the- 24.70

floor analysis

Potential emissions 24.5 99% control

reduction with controls

25
Baton Rouge Halobutyl Rubber Front-end

2006 Emissions, HCI

Emissions

Emission IDlDescription tons/year Comments

Emissions reported to EPA 76.80 Reported to EPA in ICR

Basis for beyond-the-floor 76.80

analysis

Potential emission 76.0 99% control

reduction with controls

26
Baton Rouge EPR Front-end

2005 Emissions, HCI

Emissions

Emission ID/Description tons/year Comments

Emissions reported to EPA 24.05 Reported to EPA in ICR

Basis for beyond-the-floor 24.05

an a iysis

Emissions reduction with 23.8 99% control

controls

27
Potential Back-end Emission Reductions

• In addition to cost, the cost-effectiveness calculation requires an estimate of the emis

that will be achieved; for the back-end processes, the potential emission reductions ar

EPA has estimated

Potential Emission Reductions

(Tons organic HAP)

Baytown Baton Rouge

Butyl Halobutyl Comments

Emissions basis for the 25.77 41.66

beyond-the-floor

analysis from Section

lV.B of comments

Less maintenance 20.77 34.91 Required to maintain 98%

bypasses around destruction during normal

existing RTOs operation of the existing

RTOs (See discussion in

Section IV)

Emissions after 20.56 34.56

allowance for capture

inefficiency (1%)

Emissions after 20.15 33.87

allowance for RTO

destruction inefficiency

(2%)

Note: For base years reported in ICR

28
EPA Analysis of Cost-Effectiveness for Proposed Front-end HCI Contr

Capital Annual HCI CostCost Cost Reductions effectiveness

Process $K $K Tons/Year $ITon

Baton 985 424 19.6 21,600

Rouge

EPR

Baton 985 445 76.0 5,900

Rouge

H a lob utyl

Baton 1,120 642 95.6 6,700

Rouge

Combined

Baytown 669 235 29.8 7,900

B utyl

29
EPA Analysis of Cost Effectiveness for Proposed Back-end Control

EPA Analysis

Capital Annual n-hexane CostCost Cost Reductions effectiveness

Process $K $K Tons/Year $ITon

Baton 951 1,607 34.0 47,300

Rouge

Halo b utyl

Baytown 235 181 25.7 7,000

Butyl

30
ExxonMobil Operating Costs, k$

Baton Rouge J

Halobutyl Baton Rouge

and EPR Baytown Halobutyl Baytown Butyl

Cost Front-End Butyl Front- Back-End Back-End

Category Controls End Controls Controls 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

31
EPA Policy on Residual Risk and Technology Revie

The comments below summarize ExxonMobil comments included in the comprehensive 

rulemaking package that solicited input on current EPA policies on residual risk and techn

Continuing implementation of the residual risk and technology reviews should be cons

HON court decision

- EPA has the discretion to determine that a maximum individual cancer risk level of approximately 

for a source category is acceptable; EPA is not obligated to revise industry standards to reduce li

cancer risk to one-in-one-million

- Cost is to be considered when determining the “ample margin of safety’, consistent with the Benz

- The technology review does not require a recalculation of the MACT floor standards

• The residual risk and technology reviews should be concurrent

• Risk assessments should be based on source category actual emissions

• Risk should be evaluated at the centroid of census blocks

• EPA should not expand the health information metrics beyond those already evaluated

planned added measures do not provide needed information on the cancer and non-c

the regulated source category

• In calculating cost-effectiveness in residual risk decisions, EPA should evaluate cost o

reduction basis

• In addition to the health risk metrics already established, EPA should include central te

most expected risk assessments to better communicate the conservative nature of EP

assessments

32
EPA Policy on Residual Risk and Technology Reviews 

• Application of CAA § I 12(d)(6) should incorporate the framework of § 1 12(f)(2)

• If EPA does undergo a review under CAA §1 12(d)(6), the review should be limited to e

significant changes in technology/work practices—not changing applicability threshold

• If a technology review is warranted, EPA’s approach to the scope of the technology re

indicated in the proposal is appropriate (focusing on control technologies work practic

prevention alternatives that were not identified and considered during MACT developm

• In the future, when EPA finalizes a residual risk rule with controls and work practices, 

not be applicable to low-risk sources

• EPA should delist the Butyl and EPR source categories due to low risk

33