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:NickParsons, 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 proposedrevisions 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 themeetingwas to discussExxonMobil’s comments on the October 21, 2010 proposal/supplemental proposalfor 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 ofExxonMobil Comments on EPA’s Proposed Rulemaking NESHAP forGroup I Polymers and Resins: October21, 2010 (75 FR 65068) Butyl Rubberand Ethylene Propylene Rubber Source Categories February 14, 

## 2011

# Summary ofExxonMobil Comments • Since there is no consent decree deadline to finalize a rule forthe Butyl Rubber and Ethylene Propylene Rubber source categories, EPA should take the appropriatetime to thoroughly review the comments submitted and reassess the cost-effectiveness determinations • Requiring the installation ofadditional emission controls, where the Agency has already determined that source emissions are at an acceptable risk level, is not sound regulatory policy

- 

### This proposal is inconsistentwith the EPAAdministrator’s key principles which include obtaining meaningful results with cost-effective controls

- 

### This proposal is inconsistentwith Executive Order 12866 ofSeptember30, 1993, which was recently reaffirmed in EO 13563 ofJanuary 11, 2011, thateach Agency must “propose oradopt a regulation only upon a reasoned determination thatits benefitsjustify its costs” • EPA lacks authority to 

### impose new standards underCAA

# § 112(d)(2) and (d)(3) for source categories forwhich a (d)(2) and (d)(3) standard has already been promulgated

- 

### EPAmadethe decision thatbeyond-the-floorcontrolswere notcost-effective in the 1996 rulemaking; theAgency has no authority orbasis to perform a second CAA 

### § 112(d)(2) analysis and has provided no rationale as to why the original analysis is deficientorno longerapplicable • The proposed back-end emission limits forthe Butyl Rubber source category require further modification to reflect actual emissions performance and variability • The proposed beyond-the-floorcontrols for front-end and back-end process vents are not costeffective; EPA significantly underestimated the cost ofcontrols • EPA does not have the authority to combine source categories in ordertojustify controls and the assumed shared control system is inconsistent with maintaining facility operating flexibility and how controls would be implemented • The Butyl Rubber source category subcategories should be redefined to reflect current process 

### differences 2

# Summary ofExxonMobil Comments (Cont’d) • Regular maintenance ofRegenerative Thermal Oxidizers (RTO5) is required to achieve 98% organic HAP destruction (the removal percentage assumed by the proposal) • EPA should provide 4 years to comply with any emission limits that require capital investmentfor controls (Administrator has authority to add the 4th year) • The D.C. Circuit SSM decision does not requirethe imposition ofa single emission standard to apply at all times; EPA should propose a separate emission limit or apply work practice standards during periods ofSSM • The proposed affirmative defense is unreasonable and impracticable • EPAs position that itwas not necessary to revisitthe residual risk and technology review forthe Butyl Rubber and Ethylene Propylene Rubber source categories is appropriate

- No 

### cancer risk identified; hazard index <1

- No new developments in control technology orwork 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 (EPR)

- The Butyl Rubber source category was subcategorized into Butyl Rubberand Halobutyl Rubber in that rulemaking

- The original rulemaking considered floor and beyond-the-floor options + Emission limits were established fororganic hazardous airpollutants (HAPs) from BR and EPRfront-end process vents and EPR back-end vents + Beyond-the-floor analyses showed organic HAP limits not cost-effective for BR back-end process vents and for HCI from any vents controlled by combustion 

### • Brick MACT court decision: March 13, 2007 • Residual risk and technology review completed forfour P&R 1 source categories (including BR and EPR); finalized December 16, 2008

- 

### Risk acceptable and nofurthercontrols required

- 

### No legal challenges tofinal 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, 2009 • EPA finalized rulemaking schedule in consent decree: September27, 2010

- 

### Does not include BRand EPR source categories • EPA P&R 1 proposal issued October21, 2010

- 

### Identifies some previouslyregulated emission points as “Significant Emission Points Not Previously Regulated”

- 

### Proposes additional emission limits and determinesthatsome beyond-the-floorcontrols, previously assessed in 1996, are now cost-effective and required 4

# Overview ofExxonMobil Operations • ExxonMobil facilities subjectto 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 Ii i Ive 

# Fove BRCP Halobutyl Production Facility 5

# Butyl Rubber Source 

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

- The 1996 rulemaking recognized the significantdifferences between the ExxonMobil Baton Rouge and Baytown Butyl Rubberfacilities and therefore subdivided the Butyl Rubber source category into “Halobutyl” and “Butyl” subcategories, reflecting the Baton Rouge and Baytown operations, respectively

- Halobutyl elastomers incorporate chlorine orbromine into their molecular structures

- In the last 15 years there have been projects to adjust product mix, provide operating flexibility, and improve process efficiency at Baytown; that unit now produces more Halobutyl elastomers than Butyl elastomers 

### • However, there remain basic process and emission differences between the two sites thatwarrant continuing segregation into two separate subcategories

-- 

### see ExxonMobil CBI letter • Revisions to 40 CFR subpart U are needed to reflectthe current situation

- The subcategory descriptions should be modified to distinguish between Halobutyl-only production and flexible productproduction

- The primary product determination should only be applied to facilities atthe source category level, not at the subcategory level 

### • Combining the two ExxonMobil Butyl units into the same subcategory (i.e., Halobutyl) is not a logical outgrowth ofthe proposal and would require a new beyond-the-floor analysis and a new proposal

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

### 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 controls are not justified 6

# Applicability • EPA should notfinalize the proposal to require halogen controls for BR and EPR Group 2 continuous front-end process vents

- 

### No discussion oranalysiswas provided to support/justifythis requirement

- 

### Halogen removal requirements are only associatedwith process vents thatare combustedto complywith an organic HAP removal requirement, which bydefinition doesn’tapplyto Group 2 vents and are notproposed to be applied • EPA should clarify the definition ofback-end process to avoid confusion and to remove operations that are already regulated under subpart U (e.g., surge control vessels are already regulated, but also appearto be covered by the back-end definition) • The proposed BR back-end emission limits, and compliance demonstrations, should be based on the mass ofmaterial going to the back-end, not on finished product

7

# FloorAnalysis and Emission StandardsNariability • EPA is without 

### authority to impose new standards under

# § 1 12(d)(2) and (d)(3) forthe P&R 1 source categories since a MACT standard already has been promulgated; 

# § 1 12(d)(6) provides the Agency’s 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 ofemission data; the D.C. Circuit acknowledged that data from more adverse operating conditions can inform the basis ofa standard

- Additional data was provided in the ExxonMobil CBI letterto support including variability; the data indicates that emissions per unitofproduction has varied by 43%

- The year reported (2006) for Baton Rouge Halobutyl was among the lowest in the time period; using only the 2006 data would mean thatthe site could not have metthe proposed limit in fourofthe lastfive years; this limit clearly would not represent the currentfloororthe future capability ofthe unit

- Factors that impact emissions include production, grade slate, operating and weatherconditions, process reliability and control device/service factor 

### • EPA mustrecognizethat maintenance ofthe regenerativethermal oxidizers (RTOs) is required to maintain maximum organic HAP destruction

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

- The Agency should provide for up to 240 hours/yearofRTO maintenance; eitherthe potential emissions associated with the bypass can be incorporated into the annual average emission limit orbypasses can be excluded from the compliance demonstration

- EPAwill also need to clarify thatbypasses ofback-end control equipment are allowed as long as the rolling 12- month back-end emission limit is met 8

### Butyl Rubber Back-end Floor Analysis Summary n-hexane, Tons Baytown Butyl Baton Rouge Halobutyl Basis forfloor 43.01 59.98 Variability adjustment 18.49 25.79 (43% minimum) Flooremission limit 61.5 85.8 Note: Final production-based limit should be based on production data included in ExxonMobil CBI letter 

### • Should the Agency impose back-end emission limits, the limits should include at least a 43% adjustmentforvariability and include an equivalent maintenance allowance to that demonstrated to be needed forthe existing RTOs for any additional emissions thatwill require new control

9

# Beyond-the-FloorDecisions • EPA already made the decision that beyond the floor halogen controls forcontinuous 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 forthese emission points

- In the 1996 final rule EPA noted: “The EPAexamined the impacts ofrequiring halogenated vent streams atthe Halobutyl and Butyl rubber facilities to complywith the proposed requirements forall otherelastomer subcategories (i.e., the HON-level of control). The EPA concluded thatthe costs associated with this level ofcontrol were not reasonable, given the associated emission reduction. Therefore, the proposed regulation allowed halogenated streams at Halobutyl and Butyl rubberfacilities thatwere routed to a flare orboilerpriorto proposal to continue to be controlled with these combustion devices, without additional control forthe resulting halides. ..“
- A comparable analysis was done in 1996 forthe EPR source category • 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

- EPR and the Halobutyl unit are in different source categories; CAA

### § 112(d) requires the developmentof regulations by source category or subcategory

- Halogenated front-end process vent controls forthe EPR unit are notjustified even on EPA’s cost estimate basis • EPA’s analysis based on sharing controls is inconsistent with maintaining business operating flexibility and how controls would be implemented

- The 

### two distinctbusinesses and the need to be able to maintain the controls does not supporta shared system 10

# Beyond-the-Floor Decisions (cont’d) • The proposed front-end beyond-the-floorHCI controls for Baton Rouge Halobutyl, Baton Rouge EPR, and Baytown Butyl Rubber are not cost-effective and should not be finalized; the cost effectiveness forthe proposed halogenated continuous front-end process vent control requirements ranges from $21,000/ton to $80,000/ton ofHCI • The proposed back-end beyond-the-floorcontrols for Baton Rouge Halobutyl and Baytown Butyl Rubber are not cost-effective and should not be finalized; the cost-effectiveness forthe proposed back-end control requirements is over $70,000/ton oforganic HAP

11

### ExxonMobil Front-end Control CostAnalysis Capital Annual HCI CostCost Cost Reductions effectiveness Process $K 1 $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 Halobutyl Baton 13,300 1,690 99.8 16,900 Notpractical/ Rouge legal case Combined Baytown 16,200 1,960 24.5 80,100 Butyl 1 Includes Project Services costs

Note: Annual cost includes capital cost times a capital recovery factorof0.1098 (as proposed) plus operating costs
12Annual Cost

$K 2,450 n-hexane Reductions TonslYear 33.9 Costeffectiveness $ITon 72,300 Back-end Control CostAnalysis ExxonMobil Capital

Cost $K 1 18,100 Process Baton Rouge Halobutyl 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 factorof0.1098 (as proposed) plus operating costs

13

# DevelopmentofProposal Cost Estimates • ExxonMobil utilizes a structured process to develop capital projects, including cost estimates

- Common framework across company

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

- ExxonMobil estimating tools, methods and data in existence and continuously improved forover 30 years

- ExxonMobil global cost databases are updated twice a year based on actual purchase orders, contracts, project experience and contractor and subcontractor surveys 

### • Review ofproposal and initiation ofproject developmenttriggered significant resource effort

- 

### Costestimators worked closely with site technical contacts to develop project basis, including equipment location, stream characterizations, structural modifications, project scope

- Cost analysis included site visits and review ofsupport 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 equipment and ductwork

- Otherdirect cost items (e.g., pumps, piping, instrumentation, foundations) estimated using ExxonMobil estimating methods

- Project management costs based on ExxonMobil experience; contingency added consistentwith experience for projects in the development stage
14

# Regenerative Thermal Oxidizer ProjectCosts • ExxonMobil has experience in the cost ofinstallation and operation ofregenerative thermal oxidizers at many locations • Actual project cost data supports ExxonMobil 7

s current control cost estimates and highlight how EPA’s estimates are significantly understated • Past projects reflect costs in the $7M to $14M range (excluding project services costs) Summary ofActual ProjectCapital Costs Yearof Airflow VOC Capital Project Installation (kscfm) (Iblhr) Cost ($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 airvolume, lowVOC concentration, and high moisture content, with trace quantities ofacid forming compounds • Control technology ofchoice is a regenerative thermal oxidizer; this technology has key advantages

- High destruction and energy efficiency fordilute streams

- Low NOx emissions forozone 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 ensure combustion • Control technology ofchoice is a recuperative thermal oxidizerwith a quench and acid gas scrubber; this technology has key advantages

- High destruction and energyefficiency forconcentrated streams

- All 

### surfaces contacting gas stream can be made corrosion resistant

16

# Major Deficiencies with EPA Control CostEstimates • EPA’s capital and operating cost estimates forthe controls proposed have majordeficiencies and significantly underestimatethe expected costs • EPA costs are based on a new plantwith no retrofit considerations included • Retrofit issues atthe ExxonMobil facilities include:

- Oxidizerlocation and associated ducting (and structural steel supports foroverhead locations)

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

- Minimizing process outages fortying-in and constructing the new facilities

- Dismantling ofsome existing facilities to accommodate installation ofnewfacilities

- Limited utilities availability

- Extensive additional detailed engineering associated with retrofits 

### • ExxonMobil estimate based on efficient/appropriate regenerativethermal oxidizers forback-end process vents • EPA estimate didn’t includethe extensive ducting and other auxiliary equipment, including caustic storage drum and heat exchangers • EPA used a total capital investmentfactor ofonly 1.25 to 2.20 applied to purchased equipmentto determine total capital investment; experience indicates a ratio of4 to 5 is appropriate • EPA’s indirect costs forengineering, construction supervision, scaffolding, construction equipment and otherfield expenses are significantly underestimated 17

# Compliance Time • Forthis proposal, EPA should provide 4 years to comply with emission limits that require capital investmentto install controls; the automatic one yearextension should be incorporated into the final rule (pursuantto CAA

# § 1 12(i)(3)(B) and 40 CFR 63.6(i))

- Projects, ifrequired in a final rule, will involve a complex retrofitting ofcontrol equipment into existing facilities

- Boiler/Process Heater MACT and utility rules will trigger significant demand for combustion engineers, materials, and construction resources 

### • EPA should allow fouryears forcompliance with the proposed BR source category back-end emission limits ifvariability and maintenance ofthe existing RTOs are notfully addressed

- The proposed back-end emission limitwas based on the emissions data provided for a single year and an assumption that no capital investment is required

- The proposal did not allow forvariability; without the appropriate recognition ofvariability in mostyears the floor limitwill be exceeded, necessitating capital investment

- Proposal does not currently considerthe state permit conditions available to the sites to allow for maintenance on the existing RTOs, effectively tightening the standard beyond the floor

- Loss ofSSM provisions 

### • EPA should clarify that, in the absence ofallowing fouryears as recommended above forthe proposed back-end emission limits, the first compliance demonstration is due 

### two years (24 months) following the date ofthe 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 ofthe Startup? Shutdown? Malfunction provisions is also fouryears

- 

### SSM emissions notincluded in 1996 standards development

- 

### Time needed to investcapital to improve or add controls and/orto modify work practices

19

# StartuplShutdownlMalfunction Provisions • EPA has misread Sierra Club v. EPA; EPA has the authority to apply a different emissions standard during SSM events than applies during normal operations • EPA should propose a separate emission limit or apply work practice standards during periods of SSM to appropriately recognizethe operating and emission differences during these periods

- This could include the developmentand implementation ofSSM plans 

### • The proposed affirmative defense is not an appropriate substitute for setting emission standards for malfunction periods

- An affirmative defense, even ifasserted and acceptable, still means thatthe source may be considered in violation ofthe standards with the associated legal vulnerability 

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

- Many aspects ofthe proposed affirmative defense make it unavailable as a practical matterformany ifnot most malfunctions; forexample, howwill enforcement authority determine whether ‘properdesign” or “betteroperation and maintenance practices” could have prevented a malfunction orwhethera source took “all possible steps” to minimize the impact ofthe excess emissions? • Detailed recommendations on the affirmative defense provisions are included 

### in the comment package

20

# Maintenance Provisions • Maintenance ofback-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, flare orother combustion devices because oftheir increased susceptibility to halogen corrosion and to plugging problems

- An allowance for some thermal oxidizer/halogen scrubber maintenance is allowable as long as it is reasonable and considered in the beyond-the-floorevaluation

- Recommend EPA allow up to 240 hours peryear ofthermal oxidizer/halogen scrubberoutage, as long as the front-end process vents are routed to a flare orothercombustion device during that outage

- Allowance would have a small impact on post control emissions while saving significantproduction losses, costs and emissions by avoiding unit shutdowns while conducting maintenance on these control devices 

### • Maintenance ofsurge control vessels controlled with non-water condensers

- Condensers commonly are used to control storage vessel and surge control vessel emissions in elastomer operations (material recovery, cost-effective)

- Storage vessels have planned routine maintenance provisions providing for up to 240 hours ofcontrol device outage

- Loss ofSSM provisions creates issue for surge control vessels when refrigeration system is shutdown for maintenance; potential need for installation ofalternative control (e.g. combustion) thatwill result in loss ofvent material and increased emissions

- Recommend, similarto HON and MON rule, to allow use ofthe storage vessel control provisions for surge control 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

- 

### EPAAnalysis ofCost-Effectiveness for Proposed Front-end HCI Control

- 

### EPAAnalysis ofCost-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 ofexisting 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 subjectto subpart RGTO U requirements Basis forfloor 43.01 Priorto including variability Less emissions already 17.24 Emissions from existing controlled RTO Emissions basis forbeyond- 25.77 the-floor analysis (Note 1) Note 1: This item includes emissions not routed to the RTO and emissions associated with maintaining the existing 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 forfloor 59.98 Priorto 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 maintaining the existing RTO as discussed in the comment package
24Baytown 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 notfrom 5.39 Loading rack, exchanger continuous process depressurization, safety bypass vents Basis forbeyond-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 forbeyond-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 forbeyond-the-floor 24.05 anaiysis 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 ofthe emission reduction thatwill be achieved; forthe back-end processes, the potential emission reductions are lowerthan EPA has estimated Potential Emission Reductions (Tons organic HAP) Baytown Baton Rouge Butyl Halobutyl Comments Emissions basis forthe 25.77 41.66 beyond-the-floor analysis from Section lV.B ofcomments Less maintenance 20.77 34.91 Required to maintain 98% bypasses around destruction during normal existing RTOs operation ofthe 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 ofCost-Effectiveness for Proposed Front-end HCI Control 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 Halobutyl Baton 1,120 642 95.6 6,700 Rouge Combined Baytown 669 235 29.8 7,900 Butyl

29

### EPA Analysis ofCost 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 Halobutyl 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 Reviews The comments below summarize ExxonMobil comments included in the comprehensive proposed rulemaking package that solicited input on current EPA policies on residual risk and technology reviews: Continuing implementation ofthe residual risk and technology reviews should be consistentwith the HON court decision

- 

### EPA has the discretion to determine that a maximum individual cancerrisk level ofapproximately 100-in-I million fora source category is acceptable; EPA is notobligated to revise industry standards to reduce lifetime excess cancerriskto one-in-one-million

- 

### Cost is to be considered when determining the “ample margin ofsafety’, consistentwith the Benzene NESHAP

- 

### The technology review does not require a recalculation ofthe MACTfloorstandards • 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 ofcensus blocks • 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 calculating cost-effectiveness in residual risk decisions, EPA should evaluate cost on a risk reduction basis • 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 ofEPA risk assessments 32

# EPA Policy on Residual Risk and Technology Reviews (cont’d) • Application ofCAA

# § I 12(d)(6) should incorporatethe framework of

# § 1 12(f)(2) • IfEPA does undergo a review under CAA §1 12(d)(6), the review should be limited to evaluating significant changes in technology/work practices—not changing applicability thresholds • Ifa technology review is warranted, EPA’s approach to the scope ofthe technology review as indicated in the proposal is appropriate (focusing on control technologies work practices orpollution prevention alternatives thatwere not identified and considered during MACT development) • In the future, when EPAfinalizes a residual risk rule with controls and work practices, the rule should not be applicable to low-risk sources • EPA should delistthe Butyl and EPR source categories due to low risk

33