1

MEMORANDUM 

DATE: July 19, 2010

SUBJECT: Regulatory Alternative Impacts for Group 1 Polymers and Resins Source 

Categories

FROM: Karen Marsh, EC/R Incorporated

Phil Norwood, EC/R Incorporated

TO: Randy McDonald, EPA/OAQPS/SPPD/CCG 

Paula Hirtz, EPA/OAQPS/SPPD/CCG

The purpose of this memorandum is to present the estimated impacts of regulatory 

alternatives identified to reduce hazardous air pollutant (HAP) emissions from five source 

categories that are subject to the Group 1 Polymers and Resins National Emission Standards for 

HAP (NESHAP) – 40 CFR 63, subpart U. These source categories are Butyl Rubber Production, 

Epichlorohydrin Elastomers Production, Ethylene Propylene Rubber Production, Neoprene 

Production, and Nitrile Butadiene Rubber Production. The Butyl Rubber source category is 

separated into two subcategories, Butyl Rubber Production and Halobutyl Rubber Production, 

and regulatory alternatives were evaluated independently for these two subcategories. These 

regulatory alternatives are being evaluated under EPA’s Risk and Technology Review program, 

which is addressing statutory requirements under section 112(d)(2), 112(d)(6) and 112(f)(3) of 

the Clean Air Act. Section 1 provides background information, followed by an identification of 

the regulatory alternatives in Section 2. Section 3 summarizes the estimated costs and HAP 

emission reductions of the alternatives, and Section 4 summarizes the secondary impacts.

1.0 BACKGROUND

Section 112 of the Clean Air Act (CAA) establishes a comprehensive regulatory process 

to address emissions of hazardous air pollutants (HAP) from stationary sources. In accordance 

with CAA section 112(c), EPA identifies categories and subcategories of major sources that emit 

one or more of the HAP listed in CAA section 112(b). CAA section 112(d)(2) then calls for 

EPA to promulgate national technology-based emission standards for each listed category or 

subcategory of sources. For “major sources” that emit or have the potential to emit any single 

HAP at a rate of 10 tons or more per year or any combination of HAP at a rate of 25 tons or more 

per year, these technology-based standards must reflect the maximum reductions of HAP 

achievable (after considering cost, energy requirements, and non-air health and environmental 

impacts) and are commonly referred to as maximum achievable control technology (MACT) 

standards. Section 112(d)(6) then requires EPA to review the CAA section 112(d) technologybased standards and to revise them “as necessary, taking into account developments in practices, 

processes, and control technologies,” no less frequently than every 8 years. The residual risk 

review is described in section 112(f) of the CAA. CAA section 112(f)(2) requires EPA to 

promulgate standards for each category or subcategory of CAA section 112(d) 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 consideration costs, energy, safety, and other 
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relevant factors, an adverse environmental effect. The Group 1 Polymers and Resins NESHAP 

(40 CFR 63, subpart U) regulates HAP emissions from nine source categories. In the current 

action, EPA is addressing five of the nine source categories – Butyl Rubber Production, 

Epichlorohydrin Production, Ethylene Propylene Rubber Production, Neoprene Production, and 

Nitrile Butadiene Rubber Production. Sources of HAP emissions from these processes include 

raw material storage vessels, front-end process vents, back-end process operations, wastewater 

operations, and equipment leaks. The process “front-end” includes pre-polymerization, reaction, 

stripping, and material recovery operations; and the process “back-end” includes all operations 

after stripping (predominately drying and finishing). The emission sources regulated by the 

NESHAP for these source categories are storage tanks, front-end process vents, equipment leaks, 

and wastewater operations. 

2.0 REGULATORY ALTERNATIVES

Regulatory alternatives were evaluated for the process “front-end” for Butyl Rubber 

Production, Halobutyl Rubber Production, and Ethylene Propylene Rubber Production to reduce 

hydrochloric acide (HCl) emissions. Two “front-end” process regulatory alternatives were 

identified. The first alternative was to establish an emissions limit based on the current level of 

HCl emissions. This option did not require the installation of any additional controls, only that 

HCl emissions be maintained at the current level. The second alternative was to require a 99 

percent reduction of the HCl created from the combustion of chlorinated organic compounds. In 

each case, the HCl is generated by the combustion of chlorinated organic compounds in a flare. 

Since it is not possible to install an add-on device to reduce these HCl emissions following the 

flare, the impacts are based on the replacement of the flares currently in use with incinerators 

followed by scrubbers that will achieve 99 percent reduction in the HCl emissions.

Regulatory alternatives were also identified for the process “back-end” for: Butyl Rubber 

Production, Epichlorohydrin Production, Halobutyl Rubber Production, Neoprene Production, 

and Nitrile Butadiene Rubber Production. Two alternatives were considered for each source 

category/subcategory. The alternative was to establish an emission limit based on the current 

HAP emissions levels considering existing levels of HAP stripping and recovery plus any 

existing controls. This option did not require the installation of any additional controls, only that 

emissions be maintained at the current level. The second regulatory alternative identified was to 

reduce the organic HAP emissions by requiring a 98 percent reduction in organic HAP 

emissions.

3.0 RELEVANT EMISSION POINTS AND BASELINE EMISSIONS

Information about emission points and emissions were provided by the industry in 

response to a questionnaire distributed by the EPA using their authority under section 114 of the 

CAA. 

3.1 Front-End Emissions

There are two facilities that reported emissions of HCl from the flaring of chlorinated 

organic compounds present in front-end process vent emissions, one producing Butyl Rubber 

and one producing Halobutyl Rubber and Ethylene Propylene Rubber. There are two other 
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operating facilities in the Ethylene Propylene Rubber source category, but neither reported any 

HCl emissions due to the combustion of chlorinated organic compounds. 

The two facilities are in compliance with the current MACT standards, which requires 

that organic HAP emissions from continuous group 1 front-end process vents be reduced by 

98 percent, or by using a flare. The relevant “front-end” emission points and emissions are 

provided in Table 1, along with the flow rates at the flare exits.

Table 1: “Front-End” Process Vents and Baseline Emissions

Source Category

Emission 

Point ID Pollutant Emissions (tpy) Flow Rate (ft3/sec)

Butyl Rubber FS12 Hydrochloric Acid 30.09 205.98

Methyl Chloride 0.779

Hexane 6.53

1,3 Butadiene 0.001

Xylenes 0.0002

Total Organic HAP 7.31

Ethylene 

Propylene Rubber

M-07B Hydrochloric Acid 19.77 459.4

Hexane 0.188

Total Organic HAP 0.188

Halobutyl Rubber M-07 Hydrochloric Acid 76.8 459.43

Methyl Chloride 0.53

M-07A Hexane 0.06 459.43

Total Organic HAP 0.59

3.2 Back-End Process Emissions

Following are summaries of the back-end process emissions from each of the source 

categories/subcategories. There is only one facility in each source category/subcategory.

The emissions from the back-end process operations at the butyl rubber facility are 

approximately 54 TPY. There are two separate dryer vent streams at the butyl rubber facility, 

with one stream controlled. The controlled stream emits around 28 TPY of hexane, while the 

uncontrolled stream emits around 26 TPY of hexane. The regenerative thermal oxidizer used to 

control emissions achieves approximately 98 percent control. 

The emissions from the back-end process operations at the halobutyl rubber facility are 

approximately 53 TPY. There are four separate dryer vents at the halobutyl facility and only one 

vent is controlled. The controlled vent emits around 18 TPY of hexane and 0.04 TPY of 

hydrochloric acid. The regenerative thermal oxidizer used to control emissions achieves 

approximately 97 percent control of the hexane emissions. The three uncontrolled vents 

collectively emit around 35 TPY of hexane.

The annual emissions from the back-end process operations at the Epichlorohydrin 

Elastomers facility are approximately 36 TPY. There are two separate dryer vents, one emitting 
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around 25 TPY of toluene and the other emitting around 11 TPY. Neither of these vents is 

controlled.

The annual emissions from the back-end process operations at the Nitrile-Butadiene 

Rubber facility are approximately 2 TPY. There are 11 separate dryer vents; one is controlled, 

while the others are uncontrolled. The controlled vent emits around 0.003 TPY of 1,3-butadiene 

and 0.002 TPY of acrylonitrile. The regenerative thermal oxidizer used on this vent achieves 

approximately 96 percent control of the acrylonitrile emissions, but no control of 1,3-butadiene. 

The collection of 10 uncontrolled vents emit around 0.8 TPY of 1,3-butadiene and 0.9 TPY of 

acrylonitrile. 

The annual emissions from the back-end process operations at the Neoprene Rubber 

facility are approximately 23 TPY. There are 11 separate dryer vents collectively emitting 

around 6.5 TPY of chloroprene and 16.5 TPY of toluene. None of the vents are controlled.

The baseline uncontrolled “back-end” emission points and emissions are listed in 

Table 2. The shaded emissions points are small contributors to the total HAP emissions and 

were not included in the impacts analyses discussed in the following sections. 

Table 2: Uncontrolled “Back-End” Process Vents and Baseline Emissions

Source Category

Emission 

Point ID Pollutant Emissions (tpy) Flow Rate (ft3/sec)

Butyl Rubber BPBFINISH Hexane 26.19 213

Total 26.2 213

Halobutyl Rubber M-58 Hexane 0.24 441

V-127 Hexane 23.76 253

V-131 Hexane 10.91 201

Total 34.7 454

Epichlorohydrin 

Elastomers ABKEND Toluene 24.77 154.5

BBKEND Toluene 11.2 154.5

Total 36.0 309

Neoprene EWBDRY

Chloroprene 2.325 256.5 Toluene 0.382

WWBDRY

Toluene 2.325 256.5 Chloroprene 0.382

EHDRY Toluene 11.894 476

Chloroprene 1.955

WHDRY Chloroprene 1.894 476

Toluene 1.955

EDRYC1 Toluene 0.001 343

Chloroprene 0.001

WDRYC1 Toluene 0.001 343

Chloroprene 0.001

EDRYC2 Toluene 0.001 343

Chloroprene 0.001

WDRYC2 Toluene 0.001 343
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Table 2: Uncontrolled “Back-End” Process Vents and Baseline Emissions

Source Category

Emission 

Point ID Pollutant Emissions (tpy) Flow Rate (ft3/sec)

Chloroprene 0.001

EMTNK1 Toluene 0.001 199

Chloroprene 0.001

EMTNK2 Toluene 0.001 199

Chloroprene 0.001

EMTNK3 Toluene 0.001 199

Chloroprene 0.001

Total 23.1 1466

Nitrile Butadiene 

Rubber DRYNCW 1,3-Butadiene 0.00587 184

Acrylonitrile 0.0435

PBL1 1,3-Butadiene 0.0587 193

PBL2 Acrylonitrile 0.176 193

PBL3 1,3-Butadiene 0 275

PBL4 Acrylonitrile 0 275

PBL5 1,3-Butadiene 0.119 550

PBL6 Acrylonitrile 0.357 550

SD1BLT Acrylonitrile 0.000215 9

SDN1 1,3-Butadiene 0 275

SDN2 Acrylonitrile 0 275

SDNDR2 1,3-Butadiene 0.0119 550 Acrylonitrile 0.0885

SDR1SD 1,3-Butadiene 0.615 646

Acrylonitrile 0.247

SDR2SD Acrylonitrile 0.0165 610

T45678 1,3-Butadiene 0.000177 75

Acrylonitrile 0.0000887

Total 1.74 3561

4.0 COSTS AND EMISSION REDUCTIONS OF REGULATORY ALTERNATIVES

4.1 Front-End Process Vents

As noted in Section 2, there were two regulatory alternatives identified to address HCl 

emissions from front-end process vents from the Butyl Rubber, Ethylene Propylene Rubber, and 

Halobutyl Rubber source categories/subcategories. The first alternative would ensure that the

current level of HCl emissions are maintained. The only impact of this alternative would be 

costs due to the labor costs associated with the calculations, records, and reports to demonstrate 

compliance. These costs are summarized in Table 3.
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Table 3. Estimated Impacts for Front-End Regulatory Alternative 1

Source Category

Baseline 

Emissions

(tpy)

Emission 

Reduction 

(tpy)

Capital Costs 

($)

Annual Costs 

($/yr)

Cost 

Effectiveness 

($/ton)

Butyl Rubber 7.31 0 $0 $1,000 N/A

Ethylene Propylene Rubber 0.188 0 $0 $1,000 N/A

Halobutyl Rubber 0.59 0 $0 $1,000 N/A

As noted in section 2, the organic HAP emissions from these front-end vents are already 

controlled by the flare. The costs estimated are to replace the flare with an incinerator followed 

by a scrubber. The costs were estimated using the standard OAQPS algorithms for thermal 

incinerators and acid-gas absorbers (scrubbers). In order to estimate the input organic HAP 

loading to the incinerator, the organic HAP emissions shown in Table 1 were divided by 0.02 to 

obtain the uncontrolled emissions. This assumes the flare is achieving a 98 percent reduction in 

organic HAP emissions. For example, there would be 365.5 TPY of organic HAP from the 

Butyl Rubber front-end process that would routed to the incinerator (7.31 ÷ 0.02 = 365.5). 

Because the flow rates shown in Table 1 are the flow rates for the flare, it would not be 

appropriate to assume those represent the flows that would be entering the incinerator. Based on 

information submitted by these facilities during the development of the original MACT standard, 

a flow rate of 3,500 scfm was used for all three processes.

Table 4 presents the costs based on the second regulatory alternative requiring 99 percent 

reduction in HCl emissions. Since both the Ethylene Propylene Rubber and Halobutyl Rubber 

source facilities are located at the same plant site, costs were estimated assuming a shared 

incinerator/scrubber. This is shown in the last column of Table 4. Details of these costs 

estimates are provided in Attachment 1.

Table 4. Estimated Impacts for Front-End Regulatory Alternative 2

Butyl Rubber Halobutyl Rubber

Ethylene 

Propylene Rubber

Halobuty and 

Ethylene 

Propylene 

Combined

HCl Emissions at Baseline 

(tpy) 30.1 76.8 19.8 96.6

Incinerator

 Capital $172,921 $404,703 $404,690 $481,264

 Annual $109,533 $291,598 $289,700 $471,049

Scrubber

 Capital $496,400 $580,177 $580,194 $639,136

 Annual $125,779 $153,882 $133,912 $170,451

Total Capital $669,321 $984,881 $984,883 $1,120,400

Total Annual $235,312 $445,480 $423,612 $641,500

HCl Emission Reduction 

(tpy) 29.8 76.0 19.6 95.6

Cost Effectivenesss $7,899 $5,859 $21,643 $6,710

HCl after control (tpy) 0.3 0.8 0.2 1.0
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4.2 Back-End Process Operations

As noted in Section 2, there were two regulatory alternatives identified to address backend emissions from the Butyl Rubber, Epichlorohydrin Elastomers, Halobutyl Rubber, 

Neoprene, and Nitrile Butadiene Rubber source categories/subcategories. The first alternative 

would ensure that the current level of emissions are maintained. The only impact of this 

alternative would be costs due to the labor costs associated with the calculations, records, and 

reports to demonstrate compliance. These costs are summarized in Table 5.

Table 5. Estimated Impacts for Back-End Regulatory Alternative 1

Source Category

Baseline 

Emissions

(tpy)

Emission 

Reduction 

(tpy)

Capital Costs 

($)

Annual Costs 

($/yr)

Cost 

Effectiveness 

($/ton)

Butyl Rubber 54 0 $0 $981.84 N/A

Epichlorohydrin 36 0 $0 $981.84 N/A

Halobutyl Rubber 53 0 $0 $981.84 N/A

Neoprene 23 0 $0 $981.84 N/A

Nitrile Butadiene Rubber 2 0 $0 $981.84 N/A

Table 6 presents the costs based on the second option of requiring a 98 percent reduction 

in organic HAP emissions. The costs were estimated using the standard OAQPS algorithm for 

thermal incinerators. Some of the back-end streams are already controlled. Further emission 

reductions for the controlled streams were not considered. Instead, the cost impacts were 

calculated based on the control of the uncontrolled streams that were not shaded in Table 2. 

Since the flow rates shown in Table 2 represent the flow rates of the uncontrolled streams, they 

were used as the inlet flow rates for the incinerators. Details of these costs estimates are 

provided in Attachment 2.

Table 6. Estimated Cost and Emission Reductions for Back-End Regulatory Alternative 2

Source Category

Baseline 

Uncontrolled 

Emissions

(tpy)

Emission 

Reduction 

(tpy)

Capital Costs 

($)

Annual Costs 

($/yr)

Cost 

Effectiveness 

($/ton)

Butyl Rubber 26.2 25.7 $234,589 $180,628 $7,038

Epichlorohydrin 36.0 35.3 $614,071 $1,104,543 $31,334

Halobutyl Rubber 34.7 34.0 $951,419 $1,606,579 $47,285

Neoprene 23.1 22.6 $1,275,414 $4,816,013 $212,630

Nitrile Butadiene Rubber 1.7 1.7 $1,592,255 $11,403,862 $6,687,697

5.0 SECONDARY ENVIRONMENTAL IMPACTS

While the primary impact of the regulatory alternatives is to address HCl emissions on 

the front-end and organic HAP emissions on the back-end, the application of the control 

technologies that would be required under the second regulatory alternatives can also have other 

environmental effects. These impacts can be positive, such as a reduction in non-HAP volatile 

organic compound air emissions; or negative, such as the generation of additional wastewater or 

energy consumption. In this section the secondary impacts on air pollution, water pollution, and 
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energy are discussed. The methodologies used to calculate secondary impacts can be found in 

documentation for the MACT standard.1

Air Pollution

For the sources included in this project, the secondary air pollution impacts are the 

increased criteria pollutant emissions caused by the on-site combustion of organic HAPs and 

fuels. This combustion results in the emission of nitrogenous oxides (NOx), carbon monoxide 

(CO), particulate matter (PM), and sulfur dioxide (SO2). In addition to these five criteria 

pollutants, emissions of carbon dioxide (CO2) are also expected. Table 7 presents the estimated 

secondary air impacts for regulatory alternative 2 for the front-end process vents, and Table 8 

presents those for back-end process vents. The total criteria pollutant emissions for the front-end 

are estimated to be around 7 tpy, with NOx emissions from incinerators accounting for 6 tpy. 

The total criteria pollutant emissions for the back-end are estimated to be around 267 tpy, with 

NOx emissions from incinerators accounting for 225 tpy. The CO2 emissions are estimated to be 

around 2,607 tpy and 131,086 tpy for front-end and back-end, respectively. 

Table 7. Secondary Air Impacts for Front-End Regulatory Alternative 2

Source Category

Emissions (tpy)

PM SO2 NOx CO CO2

Butyl Rubber 0.004 0.001 2 0.05 162

Halobutyl Rubber 0.03 0.006 2 0.40 1,233

Ethylene Propylene 

Rubber 0.03 0.006 2 0.40 1,219

Combined HBR 

AND EPR 0.06 0.012 4 0.70 2,445

Table 8. Secondary Air Impacts for Back-End Regulatory Alternative 2

Source Category

Emissions (tpy)

PM SO2 NOx CO CO2

Butyl 0.01 0.003 8 0.2 593

Halobutyl 0.25 0.05 17 3 10,160

Epichlorohydrin 0.17 0.03 12 2 6,891

Neoprene 0.83 0.20 55 10 33,045

Nitrile Butadiene 

Rubber 2.01 0.40 133 23 80,397

 1 Memorandum. Estimated Regulatory Alternative Impacts for Elastomer Production Facilities (Polymers and 

Resins I). Norwood, P., EC/R, to Evans, L., EPA/OAQPS/ESD/OCG. May 10, 1995. Contained in Hazardous Air 

Pollutant Emissions from Process Units in the Elastomer Manufacturing Industry--Supplementary Information 

Document for Proposed Standards. EPA-453/R-95-005a. May 1995.
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Water Pollution

The only impact on water pollution for the second regulatory alternatives identified in 

Section 2.0 is associated with the incinerator/scrubber system for control of HCl from the frontend process vents. Control of organic HAP emissions using combustion only does not result in 

any significant increase in wastewater discharge, since no water effluents are generated by the 

thermal incinerator. 

In the scrubber control system, water is used to remove the acid gas contained in the 

thermal oxidizer outlet stream. The amount of wastewater generated is equal to the amount of 

water needed by the scrubber to absorb the acid gas leaving the incinerator. It is estimated that 

about 90 million gallons of wastewater will be generated annually from acid scrubbers at Butyl 

Rubber, Halobutyl Rubber, and Ethylene Propylene Rubber facilities. Almost 60 million of this 

total is from the Halobutyl and Ethylene Propylene Rubber facility. The same assumptions were 

used for this analysis as those used in the MACT.2

 Table 9 presents the water pollution impacts 

from front-end regulatory alternative 2.

Table 9. Water Pollution Impacts from Front-End Regulatory Alternative 2

Source Category

Flow Rate to 

Scrubber (scfm)

Operating 

Hours (hr/yr)

Water Flow Rate 

(1000 gal/yr)

Butyl Rubber 3,750 8,000 30,600

Halobutyl Rubber 3,608 8,000 29,441

Ethylene Propylene Rubber 3,607 8,000 29,433

Combined HBR AND EPR 7,214 8,000 58,866

Energy Impacts

The energy demands associated with the control technologies for the second regulatory 

alternatives include the need for additional electricity and natural gas. The total nationwide 

energy demands that would result from implementing regulatory alternative 2 for front-end and 

back-end process vents are presented in Tables 10 and 11, respectively. Overall, the controls 

would require approximately 1.0 x 109 Btu electricity and 4.4 x 1010 Btu natural gas annually for 

front-end process vent control. Back-end process vents would require approximately 3.7 x 1010

Btu electricity and 2.2 x 1012 Btu natural gas annually. More details about the methodologies 

used can be found in the MACT documentation.3 

 2 See footnote 1

3 See footnote 1
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Table 10. Energy Requirements for Front-End Regulatory Alternative 2

Incinerator Scrubber

Source 

Category

Annual 

Electricity 

Cost

Electricity 

(106

BTU/yr)

Natural Gas 

Use (1000 

ft3/yr)

Natural 

Gas (106

BTU/yr)

Annual 

Electricity 

Cost

Electricity 

(106

BTU/yr)

Natural 

Gas Use 

(1000 

ft3/yr)

Natural 

Gas (106

BTU/yr)

Butyl Rubber $1,665 96 2,708 2,708 $1,283 74 0 0

Halobutyl 

Rubber $6,309 365 20,546 20,546 $477 28 0 0

Ethylene 

Propylene 

Rubber

$6,308 365 20,309 20,309 $478 28 0 0

Combined 

HBR AND 

EPR

$12,617 730 40,755 40,755 $1,290 75 0 0

Table 11. Energy Requirements for Back-End Regulatory Alternative 2

Source Category

Annual 

Electricity 

Cost

Electricity 

(106

BTU/yr)

Natural Gas 

Use (1000 

ft3/yr)

Natural 

Gas (106

BTU/yr)

Butyl $6,080 352 9,889 9,889

Halobutyl $49,137 2,844 169,328 169,328

Epichlorohydrin $33,442 1,936 114,852 114,852

Neoprene $158,683 9,185 550,748 550,748

NBR $385,458 22,311 1,339,949 1,339,949