Technical Memorandum

Date: March 31, 2011

Subject: Summary of U.S. EPA MACT Floor and Beyond-the-Floor Options for the Group I 

Polymers and Resins Portion of the 2010 RTR Proposal/Supplemental Proposal

From: Nick Parsons, EPA/OAR/OAQPS/SPPD/RCG

The purpose of this memorandum is to summarize EPA’s calculations of the MACT floor 

and the beyond-the-floor options for control of emissions from facilities in the National Emission 

Standards for Hazard Air Pollutants (NESHAP) for Polymers and Resins I (40 CFR part 63, 

subpart U), specifically for the Neoprene Rubber, Nitrile Butadiene Rubber, Epichlorohydrin 

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

1. Neoprene Rubber Production.

We identified in the provisions of the Group I Polymers and Resins MACT standard that 

apply to the Neoprene Rubber Production source category the absence of a standard for a 

significant emissions source in the category. Specifically, there are no back-end process 

operation emission limits for this source category. As these processes are major sources of 

emissions for the one facility in the source category, we are setting standards for back-end 

process operations under CAA sections 112(d)(2) and (3).

As there is only one facility in the source category, the emissions level currently being 

achieved by this facility represents the MACT floor. The annual emissions from the back-end 

process operations at this facility are approximately 33 TPY. There are 11 separate dryer vents 

collectively emitting around 33 TPY of toluene. None of the vents are controlled. Therefore, we 

have determined that the MACT floor for the back-end process is 33 TPY based on stripping and 

HAP recovery, given current production levels, but which would fluctuate proportionally with an 

increase or decrease in production levels. 

As part of our beyond-the-floor analysis, we considered alternatives more stringent than 

the MACT floor option. We identified one option using add-on emission controls that would 

require the ducting of emissions from the back-end process operations to a control device, such 

as an incinerator. This option would also require an initial performance test of the incinerator 

and continuous parameter monitoring averaged daily. The capital costs of this option are 

estimated to be approximately $1,300,000 and the total annual costs are estimated approximately 

$4,800,000 per year. We estimate that an incinerator would achieve an emissions reduction of 

98 percent, resulting in a HAP decrease of approximately 32.3 TPY, with a cost-effectiveness of 

approximately $149,000 per ton. Table 1.1 summarizes the impacts of these options.

In addition to the cost and emission reduction impacts shown in Table 1.1, we estimate 

that the beyond-the-floor option will result in increases in criteria pollutant and carbon dioxide 

emissions (PM – 0.8, SO2 – 0.2 TPY, NOx – 55 TPY, CO – 10 TPY, and CO2 – 33,000 TPY) 

and an increase in energy use of approximately 560,000 million BTU/year at a cost of 

approximately $159,000/year.

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 setting an emission standard 

that reflects the MACT floor option.
Table 1.1. Neoprene Rubber Production Facility Back-End Option Impacts

Regulatory Alternatives HAP emissions

(TPY)

Capital

Cost

(million$)

Annual

Cost 

(million$/yr)

Cost- Effectiveness as 

Compared to Baseline

($/ton HAP removed)

Baseline 33 -- -- --

1 (MACT floor) 33 0 0 --

2 (Beyond-the-floor) 0.7 1.3 4.8 149,000

2. Nitrile Butadiene Rubber Production.

We identified the absence of a standard for a significant emissions source in the category 

in the provisions of the Group I Polymers and Resins MACT standard that apply to the Nitrile 

Butadiene Rubber Production source category. Specifically, there are no back-end process 

operation emission limits for this source category. As these processes are major sources of 

emissions for the one facility in the source category, we are setting standards for back-end 

process operations under CAA section 112(d)(2) and (d)(3).

As there is only one facility in the source category, the emissions limitation achieved by 

this facility is the MACT floor. The annual emissions from the back-end process operations at 

this 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. Therefore, we have determined that the MACT floor for these processes is 2 TPY 

based on the current level of HAP stripping and recovery, given current production levels, but 

which would fluctuate proportionally with an increase or decrease in production levels. 

As part of our beyond-the-floor analysis, we considered alternatives more stringent than 

the MACT floor option. We identified one option using add-on emission controls that would 

require the ducting of emissions from the currently uncontrolled back-end process operations 

emission source to a control device, such as an incinerator. This option would also require an 

initial performance test of the incinerator and continuous parameter monitoring averaged daily. 

The capital costs of this option are estimated to be approximately $1,600,000 and the total annual 

costs are estimated to be approximately $11,400,000/year. We estimate that an incinerator 

would achieve an emissions reduction of 98 percent, resulting in a HAP decrease of 

approximately 1.7 TPY, with a cost-effectiveness of approximately $6,700,000/ton. Table 2.1 

summarizes the cost and emission reduction impacts of these options.

In addition to the cost and emission reduction impacts shown in Table 2.1, we estimate 

that the beyond-the-floor option will result in increases in criteria pollutant and carbon dioxide 

emissions (PM – 2 TPY, SO2 – 0.4 TPY, NOx – 133 TPY, CO – 23 TPY, and CO2 – 80,000 

TPY) and an increase in energy use of approximately 1,400,000 million BTU/year at a cost of 

approximately $385,000/year.

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 setting an emission standard 

that reflects the MACT floor option. However, in order to incorporate process emissions 

variability (e.g., the emissions rate may vary with product mix, in addition to production level) 

we are applying a variability factor to the MACT floor level. The facility in this source category 

submitted several years of additional emissions data, suggesting that the emissions rate in 2008 
would be more representative of expected future production rates. We found that the emissions 

rate from 2008 was 42 percent higher than that in 2009. In order to incorporate this emissions 

rate variability, we have applied a 42 percent variability factor to the facility’s baseline 

emissions, which results in a MACT floor of 2.4 TPY.

Table 2.1. Nitrile Butadiene Rubber Production Facility Back-End Option Impacts

Regulatory 

Alternatives

HAP 

Emissions

(TPY)

Capital

Cost

(million $)

Annual

Cost 

(million $/yr)

Cost- Effectiveness as 

Compared to Baseline 

(million $/ton HAP removed)

Baseline 1.7 -- -- --

1 (MACT floor) 2.4 0 0 --

2 (Beyond-the-floor) 0.04 1.6 11.4 6.7

3. Epichlorohydrin Elastomers Production.

We identified the absence of a limit for a significant emissions source within the 

provisions of the Group I Polymers and Resins MACT standard that apply to the 

Epichlorohydrin Elastomers Production source category. Specifically, there are no back-end 

process operation emission limits for this source category. As these processes are major sources 

of emissions for the one facility in the source category, we are setting standards for back-end 

process operations under CAA section 112(d)(2) and (d)(3). 

As there is only one facility in the source category, the emissions level currently being 

achieved by this facility represents the MACT floor. The annual HAP emissions from the backend process operations at this facility are approximately 36 TPY of toluene. There are two 

separate dryer vents, one emitting around 24 TPY of toluene, and the other emitting around 12 

TPY of toluene. Neither of these vents is controlled. Therefore, we have determined that the 

MACT floor for these processes is 36 TPY based on the current level of HAP stripping and 

recovery, given current production levels, but which would fluctuate proportionally with an 

increase or decrease in production levels. 

As part of our beyond-the-floor analysis, we considered alternatives more stringent than 

the MACT floor option. We identified one option using add-on emission controls that would 

require the ducting of emissions from the back-end process operations to a control device, such 

as an incinerator. This option would also require an initial performance test of the incinerator 

and continuous parameter monitoring averaged daily. The capital costs of this option are 

estimated to be approximately $600,000 and the total annual costs are estimated to be 

approximately $1,100,000. We estimate that an incinerator would achieve an emissions

reduction of 98 percent, resulting in a HAP decrease of approximately 35 TPY, with a costeffectiveness of approximately $31,000/ton. Table 3.1 summarizes the cost and emission 

reduction impacts of these options.

In addition to the cost and emission reduction impacts shown in Table 3.1, we estimate 

that the beyond-the-floor option would result in increases in criteria pollutant and carbon dioxide 

emissions (PM – 0.2 TPY, SO2 – 0.03 TPY, NOx – 12 TPY, CO – 2 TPY, and CO2 – 7,000 

TPY), and an increase in energy use of approximately 117,000 million British thermal units 

(BTU)/year at a cost of approximately $33,000/year.

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 setting an emission standard 

that reflects the MACT floor option. However, in order to incorporate process emissions 
variability (e.g., the emissions rate may vary with product mix, in addition to production level) 

we are applying a variability factor to the MACT floor level. While historical emissions data for 

the facility in this source category submitted were not available, the owner of the facility (which 

also owned the one facility in the NBR source category) noted that the back-end processes for 

this facility were very similar to those of the NBR facility. We agreed with the owner that the 

expected variability in emissions from the Epichlorohydrin Elastomers facility would be similar 

to that of the NBR facility. In order to incorporate this emissions rate variability, we have 

applied a 42 percent variability factor to the facility’s baseline emissions, which results in a 

MACT floor of 51 TPY.

Table 3.1. Epichlorohydrin Elastomer Production Facility Back-End Options Impacts

Regulatory Alternatives

HAP 

Emissions

(TPY HAP)

Capital

Cost

($million)

Annual

Cost 

($million/yr)

Cost- Effectiveness as 

Compared to Baseline

($/ton HAP removed)

Baseline 36 -- -- --

1 (MACT floor) 51 0 0 --

2 (Beyond-the-floor) 1 0.6 1.1 31,000

4. Ethylene Propylene Rubber Production.

We identified in the provisions of the Group I Polymers and Resins MACT standard that 

apply to the Ethylene Propylene Rubber Production source category the absence of a standard for 

a significant emissions source in the category. Specifically, the rule requires that emissions from 

Group 1 front-end process vents be routed to a control device that achieves 98 percent reduction 

in organic HAP emissions but does not require the control of hydrogen halides and halogens 

from the outlet of combustion devices. All four currently-operating facilities in this source 

category control the organic HAP emissions in accordance with the requirements in the rule (i.e., 

reduce organic HAP emissions by 98 percent). This represents the MACT floor for this source 

category. However, one facility routes a chlorinated organic compound to a flare, which results 

in emissions of HCl that were not regulated by the original MACT requirements. Due to the 

level of HCl emissions resulting from the combustion of chlorinated organic compounds in 

Group 1 streams, we proposed to require control of these HCl emissions for the Ethylene 

Propylene Rubber Production source category. 

As each facility in this source category currently complies with the existing MACT 

standard for organic HAP emissions, this represents the MACT floor. As part of our beyond-thefloor analysis, we considered alternatives to reduce these HCl emissions, which are more 

stringent than the MACT floor option. We identified the option of eliminating the exemption 

from the requirement to control hydrogen halides and halogens from the outlet of combustion 

devices. The one facility reports 24.1 TPY of HCl emissions in 2005 resulting from the 

combustion of chlorinated organic compounds in a flare. The other three facilities indicated that 

they do not emit any HCl emissions resulting from the combustion of chlorinated organic 

compounds. We estimated that the capital costs for the facility to replace the flare with an 

incinerator followed by a scrubber to reduce the HCl would be approximately $1,900,000 and the 

total annual costs are estimated to be approximately $441,000 per year. While there would be no 

additional reduction in organic HAP from this requirement, the HCl emissions would be reduced 

by 99 percent, or 19.2 TPY. The cost-effectiveness of this option would be approximately 

$19,000 per ton. Table 4.1 summarizes the impacts of the proposed options.
In addition to the cost and emission reduction impacts shown in Table 4.1, we estimate 

that the beyond-the-floor option will result in increases in criteria pollutant and carbon dioxide 

emissions (PM – 0.003 TPY, SO2 – 0.001 TPY, NOx – 0.4 TPY, CO – 0.04 TPY, and CO2 – 136

TPY), the generation of approximately 9 million gallons/year of wastewater, and an increase in 

energy use of approximately 140,000 million BTU/year at a cost of approximately $2,800/year.

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 setting an emission standard 

that reflects the MACT floor option. However, in order to incorporate process emissions 

variability (e.g., the emissions rate may vary with product mix, in addition to production level) 

we are applying a variability factor to the MACT floor level. The facility in this source category 

submitted several years of emissions data for our consideration. We found that the emissions 

rate varied up to 26 percent higher than that in 2005 (39 percent higher than that in 2010). This 

variability was based on the difference between the facility’s average emissions rate and the 

average emissions rate plus two standard deviations. In order to incorporate this emissions rate 

variability, we have applied a 26 percent variability factor to the facility’s baseline emissions in 

2005 (39 percent variability factor to the facility’s baseline emissions in 2010), which results in a 

MACT floor of 30.5 TPY in 2005.

Table 4.1. Ethylene Propylene Rubber Production Facility Front-End Options Impacts

Regulatory 

Alternatives

HAP Emissions

(TPY HAP)

Capital

Cost

($million)

Annual

Cost 

($million/yr)

Cost- Effectiveness as 

Compared to Baseline 

($/ton HAP removed)

Baseline 24.1 -- -- --

1 (MACT floor) 30.5 0 0 --

2 (Beyond-the-floor) 0.2 1.9 0.4 19,000

5. Butyl Rubber Production.

We identified in the provisions of the Group I Polymers and Resins MACT standard that 

apply to the Butyl Rubber Production source category the absence of standards for two 

significant emissions sources in this source category. Specifically, these situations are HCl 

emissions from front-end process vents and emissions from back-end process operations.

The rule requires that emissions from Group 1 front-end process vents be routed to a 

control device that achieves 98 percent reduction in organic HAP emissions but does not require 

the control of hydrogen halides and halogens from the outlet of combustion devices. Both 

facilities in this source category control the organic HAP emissions in accordance with the 

requirements in the rule (i.e., reduce organic HAP emissions by 98 percent). This represents the 

MACT floor for these subcategories. However, these facilities route a chlorinated organic 

compound to a flare, which results in emissions of HCl that were exempted from the original

MACT requirements. Due to the level of HCl emissions resulting from the combustion of 

chlorinated organic compounds in Group 1 streams, we proposed to require control of these HCl 

emissions. 

As each facility in this source category is currently subject to the same standard and 

complying the same way, the existing level of control for organic HAP emissions represents the 

MACT floor. The two facilities in this source category reported combined HCl emissions of 

101.6 TPY in 2006. Therefore, we have determined that the MACT floor for these processes is
each facility’s individual HCl emissions, given current production levels, but which would 

fluctuate proportionally with an increase or decrease in production levels. 

As part of our beyond-the-floor analysis, we considered alternatives to reduce the HCl 

emissions, which are more stringent than the MACT floor option. For front-end process vents, 

we identified the option of eliminating the exemption from the requirement to control hydrogen 

halides and halogens from the outlet of combustion devices. Since scrubbers could not be 

installed on the outlet of these combustion devices to reduce the HCl emissions by 99 percent, 

the facilities would need to install new recuperative thermal oxidizers followed by scrubbers to 

comply with this beyond-the-floor requirement. We estimate that the capital costs for this would 

be $4,500,000 for both facilities. The total annual costs would be around $1,200,000 per year for 

both facilities. Since there would be no additional reduction in organic HAP emissions from 

what is being achieved by the current controls, the only emission reduction would a 99 percent 

reduction in HCl emissions, or 100.5 TPY. Thus, the cost-effectiveness of these beyond-thefloor options would be approximately $12,000 per ton. Table 5.1 summarizes the impacts of 

these options.

In addition to the cost and emission reduction impacts shown in Table 5.1, we estimate 

that the beyond-the-floor option will result in increases in criteria pollutant and carbon dioxide 

emissions (PM – 0.05 TPY, SO2 – 0.01 TPY, NOx – 5.2 TPY, CO – 0.53 TPY, and CO2 – 1,823

TPY), the generation of approximately 90 million gallons/year of wastewater, and an increase in 

energy use of around 2,800 million BTU/year at a cost of approximately $56,000/year.

We believe that the costs and other impacts of these beyond-the-floor options are not 

reasonable, given the level of emission reduction. Therefore, we are setting an emission standard 

that reflects the MACT floor option. However, in order to incorporate process emissions 

variability (e.g., the emissions rate may vary with product mix, in addition to production level) 

we are applying a variability factor to the MACT floor level. The facilities in this source 

category submitted several years of additional emissions data for our consideration. We found 

that the emissions rate varied up to 190 percent higher than that in 2006 (74 percent higher than 

that in 2010). This variability was based on the difference between the facility’s average 

emissions rate and the average emissions rate plus two standard deviations. In order to 

incorporate this emissions rate variability, we have applied a 190 percent variability factor to 

each facility’s baseline emissions in 2006 (a 74 percent variability factor to each facility’s 

baseline emissions in 2010), which results in a MACT floor of 294.6 TPY in 2005.

Table 5.1. Butyl Rubber Production Facility Front-End Options Impacts

Regulatory 

Alternatives

HAP 

Emissions

(TPY HAP)

Capital

Cost

($million)

Annual

Cost ($million/yr)

Cost- Effectiveness as 

Compared to Baseline 

($/ton HAP removed)

Baseline 101.6 -- -- --

1 (MACT floor) 294.6 0 0 --

2 (Beyond-the-floor) 1.0 4.5 1.2 12,000

We also noted that there are no back-end process operation emission limits for the Butyl 

Rubber Production source category. As each facility in this source category is currently subject 

to the same standard and complying the same way, the existing level of control for organic HAP 

emissions represents the MACT floor. The annual emissions from the uncontrolled back-end 

process operations from the Butyl Rubber source category are 67.5 TPY in 2006. Therefore, we 
have determined that the MACT floor for these processes is each facility’s individual organic 

HAP emissions, given current production levels, but which would fluctuate proportionally with 

an increase or decrease in production levels. 

As part of our beyond-the-floor analysis, we considered alternatives more stringent than 

the MACT floor option. We identified one option using add-on emission controls that would 

require the ducting of emissions from the uncontrolled back-end process operations to a control 

device, such as a regenerative thermal oxidizer. This option would also require an initial 

performance test of the thermal oxidizer and continuous parameter monitoring averaged daily. 

We estimated that the capital costs of this option to be approximately $3,500,000 and the total 

annual costs are estimated to be approximately $1,500,000. We estimate that a thermal oxidizer 

would achieve an emissions reduction of 98 percent, resulting in a HAP decrease of 

approximately 66.2 TPY. The associated cost-effectiveness values would be approximately 

$23,000 per ton for Butyl Rubber source category. Table 5.2 summarizes the impacts of the 

proposed options.

In addition to the cost and emission reduction impacts shown in Table 5.2, we estimate 

that the beyond-the-floor option will result in increases in criteria pollutant and carbon dioxide 

emissions (PM – 0.18, SO2 – 0.04 TPY, NOx – 63 TPY, CO – 2 TPY, and CO2 – 7,111 TPY) 

and an increase in energy use of approximately 11,000 million BTU/year at a cost of 

approximately $223,000/year.

We believe that the costs and other impacts of these beyond-the-floor options are not 

reasonable, given the level of emission reduction. Therefore, we are setting an emission standard 

that reflects the MACT floor option. However, in order to incorporate process emissions 

variability (e.g., the emissions rate may vary with product mix, in addition to production level) 

we are applying a variability factor to the MACT floor level. The facilities in this source 

category submitted several years of additional emissions data for our consideration. We found 

that the emissions rate varied up to 45 percent higher than that in 2006 (35 percent higher than 

that in 2009). This variability was based on the difference between the facility’s average 

emissions rate and the average emissions rate plus two standard deviations. In order to 

incorporate this emissions rate variability, we have applied a 45 percent variability factor to each 

facility’s baseline emissions in 2006 (35 percent variability factor to each facility’s baseline 

emissions in 2009), which results in a MACT floor of 164.6 TPY in 2006.

Table 5.2. Butyl Rubber Production Subcategory Facility Back-End Option Impacts

Regulatory Alternatives HAP Emissions

(TPY HAP)

Capital

Cost

($million)

Annual

Cost 

($million/yr)

Cost- Effectiveness as 

Compared to Baseline

($/ton HAP removed)

Baseline 113.5 -- -- --

1 (MACT floor) 164.6 0 0 --

2 (Beyond-the-floor) 47.3 3.5 1.5 23,000

6. Shutdown Standards.

We received a comment from facilities in the Ethylene Propylene Rubber and Butyl 

Rubber source categories that organic HAP emissions that are required to be sent to emissions 

control equipment (i.e., flares) may not be able to comply with the MACT standards during 

periods of shutdown. The commenter stated that they may not always be able to route some of 

their continuous front-end process vents to a flare during periods of shutdown due to the low 
pressure or low heating value in the process vent. EPA agreed with the commenter that it is not 

possible to comply with the applicable standard during periods of shutdown, and developed an 

alternative standard applicable during these times. As part of our analysis of this alternative 

standard, EPA found that the facilities in this source category currently route their emissions to a 

flare until either the concentration of organic HAP in the process vent falls below 50 ppmv (at 

which point it no longer has enough heat content to be burned in the flare) or the pressure in the 

process vent falls below 15 psig (at which point it no longer has enough pressure to be pumped 

into the flare). As these events occur infrequently (estimated to be 1-3 times per year), emissions 

were estimated assuming a 50 ppmv HAP content stream emitting for 48 hours annually. We 

found that sources in the Butyl Rubber source category are estimated to emit 0.15 TPY and in the 

Ethylene Propylene Rubber source category to emit 0.09 TPY. Therefore, we have determined 

that these values represent the MACT floor for these process vents during periods of shutdown.

As part of our beyond-the-floor analysis, we considered alternatives more stringent than 

the MACT floor option. We identified one option using additional pumps to send the waning 

process vent stream to the flare once the organic HAP content fell below 50 ppmv or the pressure 

fell below 15 psig. For the Butyl Rubber source category, we estimated that the capital costs of 

this option to be approximately $4,300 and the total annual costs are estimated to be 

approximately $19,000. We estimate that the flare would achieve an emissions reduction of 

98 percent, resulting in a HAP decrease of approximately 0.14 TPY. The associated costeffectiveness values would be approximately $130,000 per ton for Butyl Rubber source category. 

For the Ethylene Propylene Rubber source category, we estimated that the capital costs of this 

option to be approximately $2,100 and the total annual costs are estimated to be approximately 

$4,800. We estimate that the flare would achieve an emissions reduction of 98 percent, resulting 

in a HAP decrease of approximately 0.09 TPY. The associated cost-effectiveness values would 

be approximately $53,000 per ton for Ethylene Propylene Rubber source category. Tables 6.1

and 6.2 summarize the impacts of the proposed options.

We believe that the costs and other impacts of these beyond-the-floor options are not 

reasonable, given the level of emission reduction. Therefore, we are setting an emission standard 

that reflects the MACT floor option.

Table 6.1. Butyl Rubber Production Subcategory Facility Front-End Shutdown Option 

Impacts

Regulatory Alternatives HAP Emissions

(TPY HAP)

Capital

Cost

($thousand)

Annual

Cost 

($thousand/yr)

Cost- Effectiveness as 

Compared to Baseline

($/ton HAP removed)

Baseline 0.15 -- -- --

1 (MACT floor) 0.15 0 0 --

2 (Beyond-the-floor) 0.003 4.3 19 130,000
Table 6.2. Ethylene Propylene Rubber Production Subcategory Facility Front-End 

Shutdown Option Impacts

Regulatory Alternatives HAP Emissions

(TPY HAP)

Capital

Cost

($thousand)

Annual

Cost 

($thousand/yr)

Cost- Effectiveness as 

Compared to Baseline

($/ton HAP removed)

Baseline 0.09 -- -- --

1 (MACT floor) 0.09 0 0 --

2 (Beyond-the-floor) 0.002 2.1 4.8 53,000