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MEMORANDUM

Date: August 7, 2014

Subject: MACT Floor and Beyond-the-Floor for Existing Unregulated Emission Sources in the 

Amino and Phenolic Resins Production Source Category

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

To: EPA Docket File (EPA-HQ-OAR-2012–0133)

______________________________________________________________________________

The purpose of this memorandum is to present analyses related to the maximum achievable 

control technology (MACT) “floor” and beyond-the-floor (BTF) for existing unregulated 

emission sources identified in the Amino and Phenolic Resins (APR) Production source 

category. The EPA proposed amendments to the source category on January 9, 2014, based on 

residual risk and technology reviews.

1.0 Background

1.1 Introduction

On January 20, 2000, the EPA finalized National Emissions Standards for Hazardous Air 

Pollutants (NESHAP) for the APR source category based on the requirements of section 112(d) 

of the Clean Air Act (CAA) to control hazardous air pollutants (HAP) emissions from existing 

sources. Clean Air Act section 112(d)(2) calls for the EPA to promulgate national technologybased emission standards for each category or subcategory of sources that is listed in accordance 

with 112(c) of the CAA. For “major sources” that emit or have the potential to emit any single 

hazardous air pollutant 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 MACT standards.

The MACT “floor” is the minimum control level allowed for MACT standards promulgated 

under CAA section 112(d)(3) and may not be based on cost considerations. The MACT floors 

for existing sources cannot be less stringent than the average emissions limitation achieved by 

the best performing five sources for categories or subcategories with fewer than 30 sources (APR 

has fewer than 30 sources). In developing MACT standards, the EPA must also consider control 

options that are more stringent than the floor, commonly referred to as beyond-the-floor (BTF)

options. The EPA may establish standards more stringent than the floor based on considerations 

of the cost of achieving the emissions reductions, any non-air quality health and environmental 

impacts and energy requirements. Where the EPA identifies emission points that were 

erroneously not previously regulated under a MACT rule, the EPA may identify MACT floor 

and BTF control options for existing sources, and set standards for these sources under CAA 

section 112(d)(2) and (3). The APR NESHAP, as originally promulgated, did not contain MACT 

standards for certain HAP emissions points.
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1.2 Proposed Amendments

On January 9, 2014 (79 FR 1676), the EPA proposed amendments to the APR source category 

following the results of a review required by section 112(d)(6) of the CAA, which directs the 

EPA to review previously issued NESHAP regulations and to revise them as necessary (taking 

into account developments in practices, processes and control technologies) no less frequently 

than every 8 years. Section 112(f)(2) of the CAA requires the EPA to assess, within 8 years of 

promulgation of the original NESHAP for major sources and area sources subject to MACT, the 

remaining risks due to emissions of HAP from these source categories and determine whether the

emissions standards provide an ample margin of safety to protect public health. These reviews 

are collectively referred to as residual risk and technology reviews (RTRs).

At the time of the 2014 proposal, the presence of uncontrolled continuous process vents at two 

facilities in the APR source category (Georgia Pacific in Crossett, AR, and Tembec in Toledo, 

OH) had been identified. Under CAA section 112(d)(2) and (3), the EPA proposed the following 

for the MACT floor: 

 Reduce organic HAP by 85 percent or more, or 

 Limit the concentration of organic HAP to 20 parts per million by volume (ppmv), when 

using a combustion control device, or

 Limit the concentration of organic HAP to 50 ppmv when using a non-combustion 

control device. 

2.0 MACT Floor

2.1 Continuous Process Vents – Spray Dryers 

Determination of the MACT floor

Following the January 2014 proposal, the EPA received information that there are additional 

existing facilities with uncontrolled process vents in the APR source category. According to 

industry, there are currently four facilities that operate continuous process vents in the APR 

source category, and these facilities are shown in Table 1.

Table 1. Existing APR Facilities with Continuous Process Vents – Spray Dryers 

Facility Location Control Device

Georgia Pacific Crossett, Arkansas No HAP Control

Georgia Pacific Conway, North Carolina No HAP Control

Georgia Pacific Taylorsville, Mississippi No HAP Control

Tembec Toledo, Ohio No HAP Control

These four facilities have spray dryers (Tembec has three process vents with three separate spray 

dryers at its facility and each Georgia Pacific facility has one spray dryer process vent), which is 
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a continuous process used by industry to dry different types of resins that are in liquid form into 

a powder form. Currently, these existing continuous process vents do not have emissions control 

requirements and represent a potentially significant source of HAP emissions.

As stated above, the MACT “floor” is the minimum control level allowed for MACT standards 

promulgated under CAA section 112(d)(3) and may not be based on cost considerations. Also, 

the emission standard cannot be less stringent than, but can be more stringent than, the average 

emission limitation achieved by the best performing 5 sources (for which the Administrator has 

or could reasonably obtain emissions information) in the category or subcategory for categories 

or subcategories with fewer than 30 sources. Since there are six unregulated continuous spray 

dryer process vents in the APR source category (i.e., less than 30), the MACT floor for existing 

sources is the 3

rd best source (or median) of the top five sources. 

In order to calculate the existing MACT floor, the EPA looked at HAP emissions data and 

production information provided by the two companies (Georgia Pacific and Tembec). In order 

to account for variability associated with the manufacturing process, including fluctuations in the 

amount of product produced and different types of product produced (i.e., various resin types), as 

well as to consider possible future process modifications to alter other production variables, it 

was determined appropriate to establish a production-based MACT floor. Emissions are highly 

dependent on these factors and a production-based limit takes these factors into account. The 

estimated uncontrolled production-based emission rates from spray dryer process vents are 

presented in Table 2.

Table 2. Existing Uncontrolled Continuous Spray Dryer Process Vent 

HAP Emission Rates (lb of HAP/ton of resin produced)

Process Vent

HAP Emission Rate 

(lb of HAP/ton of 

resin produced)

Rank 

(Lowest to Highest Emitter)

Spray Dryer A 0.1 1

Spray Dryer B 0.2 2

Spray Dryer C 0.7 3

Spray Dryer D 8.7 4

Spray Dryer E 10.4 5

Spray Dryer F* 13.4 6

MACT Floor Analysis

Median 0.7 lb/ton

Average 4.0 lb/ton

Standard Deviation 5.1 lb/ton

% Standard Deviation 127%

*Spray Dryer F was not included in the MACT floor analysis since it is ranked 6th. 

In order to determine the level of the MACT floor, the emission rates of the top five best 

performing spray dryers (A-E) were ranked and the median emission rate was chosen as the 
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MACT floor. Process vent C represents the median performer with a HAP emission rate of 0.7 lb 

of HAP/ton of resin produced and is therefore the MACT floor level.

The EPA looked at how the HAP emission rates from the top five process vents in Table 2 

varied, and as the table illustrates, there is a notable difference between the five process vent 

emission rates. As shown in Table 2, the percent standard deviation based on the average lb of 

HAP/ton of resin produced of the top 5 process vents is 127 percent. In order to incorporate 

variability into the final standard, the EPA applied a variability factor to the MACT floor level. It 

was determined appropriate to apply a variability factor of two standard deviations to 

accommodate for differences between facility emission rates and to allow facilities that are at or 

close to the MACT floor level some flexibility to remain in compliance as they currently operate. 

As a result, to incorporate emissions rate variability, the final MACT floor is 1.9 lb of HAP/ton 

of resin produced. This method of incorporating variability into the final standard is similar to

the approach followed for the NESHAP for Group I Polymers and Resins, which was finalized in 

April 2011 (77 FR 22566). Spray Dryers A-C will be able to meet the existing MACT floor 

without any additional controls. Spray Dryers D-F will need to have HAP controls installed in 

order to meet the MACT floor emissions rate limit. Carbon adsorbers are highly effective at 

reducing HAP emissions, and it is expected that this technology will be used to reduce HAP 

emissions from uncontrolled spray dryer process vents in order to meet the MACT floor

emissions rate limit. Based on uncontrolled levels, HAP emissions reductions of 78, 82, and 86 

percent will be needed for Spray Dryers D-F, respectively, to meet the standard.

2.2 Continuous Process Vents – Urea-Formaldehyde Concentrate (UFC) Production

Following the January 2014 proposal, the EPA was made aware of a different type of continuous 

process vent (a non-dryer type) located at Georgia Pacific’s Crossett facility. Georgia Pacific 

indicated that it has a continuous process vent that is significantly different than the six spray 

dryer process vents listed in Table 2 that would also be subject to the APR NESHAP. At the 

Crossett facility, there is a formaldehyde/urea formaldehyde concentrate (UFC) process that 

operates continuously to manufacture this product. This type of production (UFC manufacture) is 

present only at the Crossett, AR facility. The formaldehyde/UFC manufacturing production can 

switch from formaldehyde production to UFC production with few adjustments and minor 

process modifications. While this unit can produce either formaldehyde or UFC resins, the 

primary product of the unit was previously formaldehyde resins, and the unit was subject to the 

hazardous organic NESHAP (HON). However, the primary product has since switched to UFC 

resins, which are regulated by the APR NESHAP and not the HON. The Crossett facility has a

separate unit dedicated to formaldehyde production, and for approximately 6 years, the

formaldehyde/UFC unit has been producing 100 percent UFC, although it is permitted to 

produce both UFC and formaldehyde. Due to the previous requirement to control the 

formaldehyde/UFC processes according to the HON regulation, the facility routed emissions 

from the process to a regenerative thermal oxidizer (RTO) to achieve the required emissions 

reduction. However, while the primary product has switched, and the facility is no longer 

required to comply with the HON but is required to comply with the APR NESHAP for this unit, 

which does not have a HAP emissions reduction requirement, the facility has continued to 

control the emissions from this unit with the RTO. According to Georgia Pacific, the UFC 
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process operates continuously, with occasional breaks for maintenance. The process is permitted 

to run 8,760 hours per year, and generally comes close to that.

Information provided by Georgia Pacific indicates that, in addition to the formaldehyde/UFC 

production unit, several other process vents are simultaneously controlled by the same RTO. 

Thus, Georgia Pacific is unable to provide reliable RTO inlet and outlet exhaust stream data for 

just the formaldehyde/UFC production line. Although Georgia Pacific has made a good faith 

effort to provide engineering estimates of what the emission rate for the formaldehyde/UFC 

production line may be, the EPA does not believe these estimates are reliable and accurate 

enough to be used in a MACT floor analysis.

While the EPA considered including this process vent in the MACT floor analysis for continuous 

process vents associated with spray dryers described above, it was decided to not include the 

UFC process at the Crossett facility in the continuous process vents MACT floor analysis based 

primarily on the lack of reliable emissions data. The fact that the UFC process is a significantly 

different process, which exhausts to an RTO due to prior regulation by another NESHAP, also 

played a part in this decision.

The EPA notes that the emission estimates and production data provided by Georgia Pacific for 

the UFC process line results in an emission rate of approximately 0.5 lb HAP/ton of resin 

produced. If the UFC process line emission rate would have been included in the continuous 

process vent MACT floor analysis, the resulting MACT floor would have been 0.5 lb HAP/ton 

of resin produced rather than 0.7 lb HAP/ton of resin produced. Given the uncertainty believed to 

be inherent in the Georgia Pacific emission estimate, the EPA believes that the UFC process is 

operating at essentially the MACT floor level of control, and excluding this process line from the 

MACT floor analysis did not significantly affect the final result. Further, given the close 

proximity of the Georgia Pacific emission estimate to the MACT floor, subcategorization of the 

UFC process does not appear warranted.

3.0 Beyond-the Floor

For those facilities that have to control their APR process vents to meet the MACT floor level of 

control, installation of a carbon adsorber is believed to be the most logical choice. A scrubber is 

also a viable option, although facilities without existing wastewater treatment capabilities would 

incur significant additional expense to dispose of the resulting wastewater from the scrubber. The 

BTF control option identified for spray dryers in the APR source category that may achieve a 

higher level of control than a carbon adsorber or scrubber is an RTO. This BTF option would 

require a significant capital investment as well as substantial annual operation and maintenance 

costs. 

Spray Dryers A-C are located at one facility, and it is assumed that one RTO would be used to 

control all three dryers. The capital cost associated with an RTO for Spray Dryers A-C is 

estimated to be $2.2 million with an annual cost of $773,000 per year. The cost per ton of HAP 

removed is approximately $40,000 for these spray dryers. The capital cost for Spray Dryers D-F 

is more than $2 million per facility with annual costs between $700,000 and $800,000 per year

per facility. The cost per ton of HAP removed varies from $11,000 to $30,000 per ton of HAP 
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removed for Spray Dryers D-F. The costs and cost effectiveness of an RTO are shown in Table 

3. More information on how the costs and cost effectiveness were calculated are available in the 

memorandum entitled “National Impacts Associated with the Final NESHAP for Existing Amino 

and Phenolic Resins Continuous Process Vents,” available from the rulemaking docket (EPAHQ-OAR-2012-0133). 

Table 3. Cost Effectiveness of BTF Option for APR Spray Dryers1

Process Vent

Baseline 

Emissions 

(tpy)

Emissions 

Reductions 

(tpy)

Capital

Cost 

Annual 

Cost

Cost 

Effectiveness 

($/ton HAP)

Spray Dryers A-C 19.8 19.4 $2.2 million $773,000/yr $40,000

Spray Dryer D 63.9 62.7 $2.2 million $784,000/yr $12,500

Spray Dryer E 24.3 23.8 $2.1 million $723,000/yr $30,000

Spray Dryer F 76 74.5 $2.3 million $822,000/yr $11,000

Total 184.0 180.5 $8.8 million $3.1 million/yr $17,000

1Some discrepancies are due to rounding. 

The incremental cost effectiveness associated with requiring an RTO instead of a carbon 

adsorber on the spray dryers is presented in Table 4. As the table shows, the incremental cost 

effectiveness of requiring an RTO instead of a carbon adsorber on Spray Dryers A-C is 

800,000/ton HAP. For Spray Dryers D-F the incremental cost effectiveness associated with using 

an RTO instead of a carbon adsorber ranges from approximately $40,000 to $115,000.

Table 4. Incremental Cost Effectiveness of BTF Option for APR Spray Dryers1

Process Vent

Emissions 

Reductions 

(tpy)

Annual 

Cost

Incremental 

Cost 

Effectiveness

($/ton HAP) Carbon 2

Adsorber RTO Carbon Adsorber RTO

Spray Dryers A-C 18.8 19.4 $294,000/yr $773,000/yr $800,000

Spray Dryer D 49.9 62.7 $286,000/yr $784,000/yr $39,000

Spray Dryer E 19.9 23.8 $282,000/yr $723,000/yr $114,000

Spray Dryer F 65.4 74.5 $294,000/yr $822,000/yr $58,000

Total 154.0 180.5 $1.2 million/yr $3.1 million/yr $74,000

1Some discrepancies are due to rounding. 

2For Spray Dryers A-C the incremental cost effectiveness is the $/ton of HAP reduced associated 

with increasing the control efficiency from 95 to 98%. For Spray Dryers D-F it is the difference 

between 78/82/86% to 98%.