0223.04.020 1

Date: November, 2011 

To: Brian Shrager, US EPA 

From: Eastern Research Group, Inc. 

Subject: Revised MACT Floor Analysis (November 2011) for the Industrial, Commercial, and Institutional 

Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants – Major Source 

The purpose of this memorandum is to present the results of the maximum achievable control 

technology (MACT) floor determinations for boilers and process heaters at major sources of hazardous 

air pollutants (HAP). We determined the MACT floors using data obtained from two recently 

implemented Information Collection Requests (ICRs) approved under OMB Control No. 2060-0616: ICR 

numbers 2286.01 and 2286.03, as well as new data and data corrections received before, during and 

after the public comment period on the proposal.1,2,3 Data from both phases—the 2008 Combustion 

Survey and the 2009 Test Plan for boilers and process heaters—were analyzed for currently operating 

boilers and process heaters. We ranked emission test averages for each boiler and process heater, 

calculated MACT floor averages, and conducted emission data variability analyses. We determined the 

MACT floor emission limits based on the results of these analyses. This memo is a follow-up to the 

memorandum prepared to document the MACT floor methodology in the March 2011 proposal and this 

feature highlights changes to the methodology and results since the previous analysis.4 The following 

sections address the methodology used to calculate pollutant limits for existing and new sources. The 

memorandum is organized as follows: 

1.0 Floors for Existing Sources 

1.1 Methodology for MACT Floors for Existing Sources 

1.2 Incorporating Data Variability 

1.3 Calculating Emission Limits

1.4 Data Not Considered in the MACT Floor Analysis for Existing Units

2.0 Floors for New Sources 

2.1 Methodology for MACT Floors for New Sources 

3.0 References 

Appendix A: Hg, HCl, and TSM Variability as a Function of Fuel Variability 

Appendix B: Ranked Emission Data for MACT Floor Analysis 

Appendix C: Upper Prediction Limit (UPL) Calculations for Existing Sources 

Appendix D: Summary of Statistical, Fuel, and RDL Variability for Existing Sources 

Appendix E: UPL Calculations for New Sources 

Appendix F: Summary of Statistical, Fuel, and RDL Variability for New Sources 
0223.04.020 2

1.0 Floors for Existing Sources 

1.1 Methodology for MACT Floors for Existing Units 

For existing sources, MACT cannot be less stringent than the average emission limitation 

achieved by the best performing 12 percent of existing sources (for which emission information is 

available) for categories and subcategories with 30 or more sources or the best performing five sources 

for subcategories with less than 30 sources. The size of the subcategory was determined according to 

the number of units in the boiler and process heater inventory, not the number of units within each 

subcategory that had emission data available. 

The revised MACT floor analysis has the following differences from the analysis conducted for 

the 2010 proposal for the Industrial, Commercial, and Institutional Boilers and Process Heaters National 

Emission Standards for Hazardous Air Pollutants: 

1) New floors were developed for eight total selected metals (TSM8) based on the reported 

emissions for arsenic, beryllium, cadmium, chromium, lead, manganese, nickel, and 

selenium. In order for the TSM8 data to be considered in the floor analysis all eight metals 

needed to be reported in a numeric format that could be standardized for each test run. 

This qualifier was included to avoid basing a TSM8 standard on data that represented less 

than the sum of all eight metals. 

2) Variability factors for TSM8 were assessed using fuel variability from units in the top 12 

percent. The same approach that was used in the March 2011 fuel variability analysis for Hg 

and Chlorine was adopted here. In order for fuel variability to be included in the analysis, all 

eight metals needed to be reported in a numeric format that could be standardized for each 

fuel sample. 

3) Statistical variability was incorporated using the 99% Upper Prediction Limit (UPL) for CO (a 

change from the 99.9% UPL that was used for CO in the final rule), in order to be consistent 

with the UPL statistic selected for the other regulated pollutants. 

4) The computed UPLs in each subcategory were compared to a value three times the 

representative detection limit (3xRDL), as discussed in another memorandum.5 The 

methods for computing the 3xRDL value have changed since the March 2011 final rule. 

However, consistent with the final rule, if the computed UPL was less than the 3xRDL value, 

the emission standard was set to the 3xRDL value. 
0223.04.020 3

5) New subcategories were added based on comments received during the public comment 

period and reconsideration periods. New subcategories since the March 2011 final rule 

include: separate subcategories for light and heavy liquids based on the design differences 

of these units; separate subcategories for dutch ovens and suspension burner biomass units 

given the large differences in the design of these two combustors; Inclusion of pile burners 

in the dutch oven subcategory because dutch ovens are defined as a type of pile burner; 

removal of pile burners from the stoker/sloped grate/other subcategory (some of these 

units had previously been considered ‘other’ units and were evaluated as part of the 

stoker/sloped grate/other subcategory); and splitting the stoker/sloped grate/other 

subcategory according to the type of fuel combusted, which influences the design of the 

units (stokers designed to burn kiln-dried biomass are separated from stokers designed to 

burn wet biomass as a result of fuel handling and design differences between these units). 

6) The MACT floor analysis for filterable particulate matter (PM) and the alternative TSM8 limit 

were analyzed on a combustor-specific approach given the design differences in certain 

combustors that affect particle size. Now CO, PM, and TSM8 emissions are all analyzed on a 

specific combustor basis. 

7) Instrument calibration and measurement error were incorporated into the CO analysis 

before computing a floor. The revised CO instrument calibration and error measurement 

calculations are discussed in another memorandum.6

8) After further review of certain best performer test reports to assess data quality, some tests 

were removed from the analysis because they did not pass a quality review. Efforts were 

made to correct erroneous data when laboratory appendices were available to re-compute 

the numbers, but this was not possible in all cases. A discussion of the approaches used and 

findings from the data quality review process are available in another memorandum.7 

9) The alternative MACT floor analysis option was to consider PM emissions as a fuel-based 

pollutant instead of a combustor-based pollutant. 

Based on the 2008 Combustion Survey and additional new data submitted during the public comment 

and reconsideration period, there are 14,411 boilers/process heaters currently in operation at major 

sources in the United States and United States territories. Emission test data and additional Hg, TSM8, 

and Cl fuel analysis data from uncontrolled liquid units were ranked and analyzed. These data were 

obtained from the public comment period, Boiler Survey, when available, or when requested under the 
0223.04.020 4

ICR phase II testing plan, and compiled into an emissions database.1,2,3 We used data and information 

contained in these databases to develop the MACT floors.8,9 

We ranked the minimum stack test means for each pollutant in each subcategory. We 

conducted this ranking according to the fuels the unit was burning during the test for Hg and HCl. 

Because emissions of fuel-based HAP (e.g., Hg, acid gases) depend on the fuel used rather than the 

design of the combustion chamber, MACT floors for fuel-based HAP were based on data from all boilers 

and process heaters firing the minimum threshold (90%) of each fuel group. Emissions of organic HAP, 

CO, PM, TSM8, fluctuated according to the design of the combustion chamber. Combustor design 

subcategories considered in this analysis were Pulverized Coal (PC), Fluidized Bed (FB), and Stoker/Other 

for units designed to burn coal and other fossil solids; FB, Dutch Oven/Pile Burner, Suspension Burners, 

Fuel Cells, hybrid grate/suspension, Stoker/Sloped Grate/Other burning kiln-dried biomass, and 

Stoker/Sloped Grate/Other burning wet biomass for units designed to burn biomass/bio-based solids; 

and light, heavy, and non-continental liquid for units designed to burn liquid fuels. Because of these 

differences, MACT floors for PM, TSM8, and CO were based on unique combustor design characteristics 

in addition to the type of fuel the boiler is designed to burn. We ranked the data according to the 

combustor design categories and according to the fuel the unit was burning during the test. If the unit 

was fired with at least 90 percent biomass during the test, the test data were assigned and ranked in 

one of the seven combustor design subcategories for biomass and bio-based solids. If the unit was fired 

with at least 90 percent coal or other fossil solids during the test, the test was classified and ranked in 

one of the three combustor design groups for coal and other fossil solids. If a unit was fired with at least 

90 percent heavy liquid fuels during the test, the test was classified and ranked in either the liquid or 

non-continental liquid subcategories, depending on the location of the unit. If a unit was fired with at 

least 90 percent light liquid fuels during the test, the test was classified and ranked in either the liquid or 

non-continental liquid subcategories, depending on the location of the unit. However, none of the 

available test data from non-continental liquid units were conducted while firing light liquid fuels. If a 

unit was fired with any amount of heat input from coke oven gas in combination with other gaseous 

fuels during the test (with the exception of co-fired with blast furnace gas due to the exemption of this 

fuel type from the rule), the test was classified and ranked in the MACT floor units designed to burn 

other process gases (gas 2). We did not assume that coke oven gas would be able to meet the fuel 

specification that is in the proposed rule, although some coke oven gas may meet the specification. 

Some units reported test burns on more than one material or blend of materials in different 

tests. For example, units burning oil during process interruptions might have submitted test results 
0223.04.020 5

when firing coke oven gas and when firing fuel oil. The emission test data based on fuel oil would have 

been characterized and ranked in the “boilers designed to burn liquids” subcategory, but the emission 

test data based on coke oven gas would have been ranked and analyzed in the “boilers designed to burn 

other gas” subcategory. Given the ability for units to switch subcategories based on their actual annual 

heat input, we remain consistent with the approach in the March 2011 final rule that it is appropriate to 

rank and analyze tests separately, based on what materials were fired during the test. It is important to 

note that not all units are designed to fire or are capable of firing different fuels, and the standards were 

developed in recognition of this fact. 

Emissions of CO were ranked according to either their reported measured values, or the 

adjusted values that incorporate measurement calibration error under the revised analysis of 

instrument error. The methodologies used to adjust CO measurements to incorporate instrument 

measurement error are discussed in another memorandum.6

Consistent with the March 2011 final rule, we then identified minimum emission test averages 

in the best performing 12 percent (or top 5 units) for each subcategory. To determine the number of 

boilers/process heaters in the best-performing 12 percent, we multiplied the number of sources with 

emission data in each subcategory by 12 percent and rounded up to the nearest whole integer. For 

example, 12 percent of a category with 103 emission test averages is 12.36, so we would have averaged 

the emission test data from the top 13 boilers/process heaters. This roundup approach is consistent 

with the approach used by statisticians in survey sampling.11 However, in this revised analysis units that 

were tied as top performers were further evaluated in order to determine if their data would be 

incorporated into the statistical variability analysis discussed below. We included the number of tests 

available at each boiler in the ranking in order to assess any ties among top performing boilers. Taking 

the above example, if the boilers ranked #13 and #14 both had the same minimum test average (after 

rounding to two decimal places for PM, Hg, HCl, or TSM8 or rounding to the nearest ppm for CO), and 

boiler #14 had more tests available than boiler #13, we would use the data from boiler #14 instead of 

boiler #13 in order to better assess variability in emissions among best performers. If both boilers #13 

and #14 had the same amount of tests, the tests were ordered alphabetically by Facility ID in order to 

avoid pulling too many units into the floor analysis. Appendix B notes where ties occurred in each 

dataset. 

For stokers/sloped grate/other units designed to burn wet biomass, a large number of units 

were assigned to the default CO span values discussed in another memorandum.15 As a result there 
0223.04.020 6

were multiple units tied for the best performing 12 percent. However, including all of the units that 

were tied for best performers in this case would reduce the variability of the dataset and would not 

represent the variation in CO that is typical at wet biomass boilers. In this case, the units that were tied 

were sorted alphabetically by facility ID and unit ID, and the top 10 units were selected as inputs into the 

UPL equations. 

1.2 Incorporating Data Variability 

Three types of data variability were evaluated to determine the emission levels achieved by the 

best performing sources over the long term. The previous MACT floor memorandum discusses statistical 

variability and our statistical methods have not changed since the March 2011 final rule analysis with 

the exception of selecting a 99% confidence level for CO in order to be consistent with the other 

regulated pollutants. A revised 3xRDL methodology and results are discussed in detail in another 

memorandum.5Small changes to fuel variability are discussed below to accommodate the new TSM 

standard and comments received during the reconsideration process. Boiler operating load variability 

was not assessed under the stack-test based MACT floor methodology since the rule requires units to 

conduct stack tests at representative operating loads and does not mandate continuous emissions 

monitoring over varying loads. Another memorandum discusses an alternate CO CEMS-based 

methodology that better incorporates boiler load variability. 

12 

Fuel Analysis Variability 

Fuel analysis data for Hg, TSM8, and HCl (converted from Cl) were standardized to a lb/million 

Btu (lb/mmBtu) basis, using data standardization techniques discussed in other memoranda.13, 14 Next, 

the units that reported fuel analysis data paired with stack tests were identified by using the database 

field in the Data: Fuel Analysis table, “FM_analysiswithEmissionTest”. Since the Phase II test plan 

requested paired fuel analysis data for each stack test run, the fuel analysis “Sample ID” associated with 

each fuel analysis were matched up with the individual test run “Test ID.” Since fuel sampling IDs 

reported in the spreadsheet and test IDs reported in the Electronic Reporting tool sometimes had 

different naming conventions, the IDs of the units in the top 12 percent were reviewed and a secondary 

test ID column was created in order to allow these two data tables to be linked and compared. 

After these identifiers were added to the database, the same approach as discussed in the fuel 

variability section of the previous MACT floor memo was taken for single and multi fuel units as well as 

removing outliers in each of the factors for each subcategory. 
0223.04.020 7

Appendix A-1 shows the calculated FVF analysis for Hg, HCl, and TSM8 for each subcategory 

where data was available. 

Appendix A-2 shows the calculated fuel variability factors used in the MACT floor analyses for 

coal/fossil-solid, biomass/bio-based solid, all solid fuels, all liquids, heavy liquid, and light liquid 

subcategories. 

For existing solid fuel units, EPA reviewed the fuel variability in the UPL calculations prior to 

multiplying the results by the FVF. In the case of the solid fuel subcategory the fuels used in the top 

performing boilers for Hg and HCl varied widely, including coal, petroleum coke, tire-derived fuel, as well 

as several types of biomass fuel. Based on the heterogeneous make up of the best performing units and 

the large number of test runs in the best performing dataset, we determined that the UPL calculation 

alone considered sufficient variability in fuel types from best performing units and it was unnecessary to 

incorporate additional fuel variability through the use of a FVF. For new solid fuel units, the top 

performing boiler for Hg does not have paired fuel sampling data with emission stack data and a fuel 

variability factor could not be developed. Also, for new solid fuel units the new source floor for HCl is 

defaulted to the existing source floor so the FVF does not apply. For TSM8, since each subcategory is 

specific to a unique combustor design and include a smaller pool of test runs in each UPL analysis, the 

statistical analysis does not sufficiently address fuel variability and a FVF was applied to each 

subcategory where data were available. 

For existing and new liquid fuel units, the fuels making up the best performing units 

demonstrated less variability in their composition and type, and there were a smaller pool of available 

tests runs. EPA determined that an additional fuel variability factor was necessary in these cases. There 

were no fuel variability data available for the process gas best performing units. 

1.3 Calculating Emission Limits 

The emission limits are summarized for each subcategory in Tables 1 and 2. The data ranked and 

analyzed for the MACT floor at existing units is shown in Appendix B, and the UPL floor calculations for 

each subcategory and each pollutant are shown in Appendix C. 
0223.04.020 8

Table 1: Summary of Calculated MACT Floor Limits for Existing Boilers and Process Heaters at Major Sources of HAP under 

Recommended Approach 

Subcategory 

Filterable 

Particulate 

Matter 

(lb/MMBtu) 

Hydrogen 

Chloride 

(lb/MMBtu) 

Mercury 

(lb/MMBtu) 

CO 

(ppm @ 3% O2) 

TSM 8 

(lb/MMBtu) 

All Solid Fuels 0.022 3.1E-06

Coal/Fossil Solid

FB 0.088 56A1.7E-05

PC 0.044 41A5.9E-05

Stoker/Other 0.028 220A8.3E-05

Biomass/Bio-based 

Solid 

Dutch Oven/Pile 

Burner 

0.036 810A2.5E-04 

FB 0.11 370A1.2E-03

Fuel Cell 0.033 1,500 4.9E-05B

Suspension Burner 0.051 58A1.1E-03

Suspension/Grate 0.44 3,900A4.9E-04

Wet Biomass 

Stoker/Other 

0.029 790A5.7E-05 

Dry Biomass 

Stoker/Other 

0.32 250A4.0E-03 

Liquid 0.0012 2.6E-05

Heavy Liquid 0.062 10A2.5E-04

Light Liquid 0.0034 7

A

4.1E-04

Non-Continental 

Liquid 0.008 18A

6.2E-04 

Process Gas 0.0067 0.0017 7.9E-06 4

A

2.4E-04

Notes: 

• Red text indicates at least one test run used to calculate the UPL limit was reported as non-detect data. 

• Blue shaded cells indicate limits that incorporate fuel analysis variability. The Hg, HCl floors for liquid units incorporate both the 

3*RDL value and fuel analysis variability. These values represent the 3*RDL multiplied by the FVF. 

• Green cells indicate limits that are based on the 3*RDL approach. 

• Although default maximum calibration errors were used for CO, if data was flagged as non-detect when initially reported it was still 

considered to be non-detect data even if the value defaulted to the calibration error. 

A CO MACT floor is based on adjusted data that consider measurement error for measurements obtained with an instrument test 

method. 

B This represents the beyond the floor limit, as identified in another memorandum.16 Appendix B shows what the 99% 

UPL calculation would be for this subcategory. 

Table 2: Summary of Calculated MACT Floor Limits for Existing Boilers and Process Heaters at Major Sources of HAP under 

Alternative Approach 

Subcategory 

Filterable Particulate 

Matter 

(lb/MMBtu) 

All Solid Fuels 0.035

All Liquid Fuels 0.008
0223.04.020 9

Notes: 

• All other limits are the same under the alternative approach except for the PM limits in each of the liquid and solid fuel combustorbased subcategories. Under the alternative approach there is no alternative TSM8 emission limit. 

• Red text indicates at least one test run used to calculate the 99% UPL limit was reported as non-detect data. 

1.4 Filling Data Gaps 

For subcategories with no applicable test data for a given pollutant, floor limits from other 

subcategories were assigned in order to fill the gaps in data. In both of these instances the subcategories 

were created in response to compelling public comments and data provided to create a new 

subcategory. Since these subcategories were not envisioned at proposal the 2009 ICR test plan was not 

targeted to fill data gaps for these subcategories and data from the most similar subcategories were 

used as a proxy to fill data gaps and establish emission limits for these subcategories. The appropriate 

action taken to fill these data gaps are described below. 

• Non-continental liquid: No test data from units located in non-continental states or territories 

were available for HCl or TSM8. For these pollutants, a separate floor was calculating using the 

top performing tests firing #6 fuel oil since this is the type of liquid fuel reportedly fired at the 

non-continental refineries. 

1.5 Data Not Considered in the MACT Floor Analysis for Existing Units

For HCl, Hg, TSM8, and PM, data upstream of the control device were not considered in the 

MACT floor analysis because the control device is expected to achieve emission reductions. The location 

of the test is denoted in the “Location” field of the Data: EmissionsTest Table. If the test location was not 

reported, it was assumed to be downstream of the control device since this data represented the vast 

majority of data in the database. The upstream/downstream location was not a limiting factor when 

identifying suitable data for CO unless the control device reported was a CO catalyst. 

Some facilities submitted emission test data based on previous control configurations that are 

no longer installed on the unit. Emission data reported while using these previous control configurations 

were not used to establish the MACT floor. Table 3 shows which control configurations were not 

considered in the MACT floor analysis. Any emissions associated with the control configurations at these 

units were not considered in the analysis, except the emissions for CO, as CO is not expected to be 

affected by the control devices currently installed on the unit. 

Table 3: Deleted Control Configurations for MACT Floor Analysis 

FacilityID UnitID Previous Control 

Configuration Description

Reason for Removing

ALWeyerhaeuserMillport Boiler No. 1 No HAP APCD Control Wet scrubber installed in 2006 

after emissions testing 

ARGeorgiaPacificCrossett93 SN-WB1 Wood 

Boiler

Wet Scrubber Wet scrubber no longer 

installed at unit

IDRileyCreekLumber HFB1 Electrostatic Precipitator FF now installed on unit (no 

installation date known) 
0223.04.020 10

FacilityID UnitID Previous Control 

Configuration Description

Reason for Removing

IDRileyCreekLumber HFB2 Electrostatic Precipitator FF now installed on unit (no 

installation date known) 

ILBungeDanville CFB Boiler Fabric Filter Dry injection added to FF 

(unknown installation date) 

INNotreDame B-2 Cyclone or Multiclone Multiclone replaced by FF in 

1952 

INNotreDame B-3 Cyclone or Multiclone Multiclone replaced by FF in 

2008 

INNotreDame B-4 Electrostatic Precipitator Multiclone replaced by FF in 

2008 

MIDecorativePanels Boiler #3 Cyclone or Multiclone FF added to multiclone in 2008

MIMichiganSugarCaro Boilers #1 & #2 No HAP APCD Control Venturi installed in 2007

MSMasoniteLaurel BB-003 Wet Scrubber Wet scrubber removed in 2007

NCNC_DukeUniversity_Durham 7754-01 Fabric Filter Dry injection added to FF in 

2007

NCNC_DukeUniversity_Durham 7754-01 Fabric Filter Dry injection added to FF in 

2007

NCNC_DukeUniversity_Durham 7754-03 Fabric Filter Dry injection added to FF in 

2007

OHMedicalCenterCo1915 B003 & B004 Fabric Filter Dry injection added to FF in 

2007

ORRoseburgCoquille Boiler 1 Cyclone or Multiclone ESP added to multiclone in 2006

SCNewSouthCamden WWB1 Cyclone or Multiclone ESP installed in 2007

SCNewSouthCoConway WWB1 Cyclone or Multiclone ESP installed in 2007

VAGPJarrattFiberboard EP-15 No. 3 

Keeler Boiler 

Cyclone or Multiclone ESP added to multiclone in 2007

VASmurfitStoneWestpt PB08 Electrostatic Precipitator Wet scrubber installed in 2007

WIDomtarNekoosa B22 - Boiler No. 

7 

Electrostatic Precipitator Unit does not actually employ 

any controls 

WVDuPontWashingtonWorks P03 Cyclone or Multiclone Multiclones in process of 

removal 

For uncontrolled light liquid units with fuel analysis data for Hg, HCl, or TSM8, the fuel analysis 

data were only used if there was not an emission test available for that unit for Hg, HCl, or TSM8. Using 

both fuel analysis and emission test data associated with the same unit would be double-counting 

emission data and would be inconsistent with the approach to use the minimum available emission data 

for each unit to identify the units in the top 12 percent. 

Some emission data for CO, PM, and TSM8 were based on common stacks that are fed from 

units in more than one subcategory. Because these floors are based on combustor design, only those 

emissions are based on units with the same combustor were considered. If the combustor design 
0223.04.020 11

classification in the Data: EmissionsTest table listed “Multiple Combustor Designs,” this data was not 

used in the MACT floor calculations for CO, PM, or TSM8. 

Finally, there were some specific data reported that were excluded from the MACT floor analysis 

for site specific reasons. The data table “Data: EmissionsTest” in version 7 of the emission test database 

contains two fields, “Ignore for Floor?” and “Note” which flag data that were disregarded from the 

analysis and provides a reason why the data were not considered in the analysis based on further review 

of the data and comments received as part of the reconsideration process. 

Appendix D summarizes all of the variability analysis for new source floor calculations by 

subcategory. 

2.0 Floors for New Sources 

2.1 Methodology for MACT Floor at New Units 

The same methodology used to calculate the MACT floors for existing sources, as discussed in 

Section 2.0, was used to calculate the floor for new sources, with four exceptions. Additional exceptions 

needed to be considered for new source limits to ensure that the floor computations are representative 

of the best controlled similar source for an entire subcategory. First, if the calculated floor for new 

sources was less stringent than the calculated floor for existing sources, the floor corresponding to the 

same subcategory for existing sources was used as the basis for the floor for new sources. Although the 

minimum average test run for the best performing source resulted in the lowest three-run average test, 

the 99% UPL-based limit incorporated variability between test runs. As the sample size—in this case the 

number of test runs—gets smaller, the t-statistic increases. When the sample size of test runs is small, 

and there is a large variability between test runs, the calculated limit using the UPL approach can be 

larger than the variability among a larger set of test runs from units in the best performing 12 percent, 

especially if the performance of the best performing units is comparable. 

Second, if the lowest emitting unit had less than three test runs, the unit with the next lowest 

emissions based on at least a three-run test average was used as the basis for the MACT floor from new 

units. Using the lowest emitting unit with three test runs ensures that adequate variability can be 

incorporated into the limit to guarantee that future sources can repeatedly meet the limit during their 
0223.04.020 12

compliance tests. There were no instances where the top ranked unit was disregarded due to not having 

three test runs. 

Third, if the top ranked unit was represented by an emission test based on co-firing of fuels that 

are not in the same subcategory, this test was not considered to be representative of the best similar 

source for the subcategory. The unit with the next lowest emissions that is based on a test firing 100 

percent of the fuel category was used in the basis of the floor. 

1) The PM MACT floor for new and existing suspension burners designed to burn biomass 

fuels are based on a single unit given the number of units in the subcategory with 

available test data. The top two ranked units are co-firing biomass with natural gas so 

the floor is based on the #3 ranked unit (OHSauderWoodArchbold B009). 

2) The new source TSM8 MACT floor for stoker/sloped grate/other units designed to burn 

wet biomass is based on the second ranked unit, IDPotlatch PB-2 Riley. The top ranked 

unit is co-firing natural gas during its compliance test. 

3) The new source CO floor for heavy liquid units is based on the third ranked unit 

(VANewportNewsShipbuildingDryDock 78-E1) since the lowest test is based on a unit cofiring #6 fuel oil with natural gas the second ranked unit only had 2 test runs. 

Fourth, if the top ranked unit was based on a process-specific fuel that could not be reasonably 

purchased or obtained by other sources in the subcategory, we selected the unit with the next lowest 

emissions as the basis of the floor calculations. 

1) For the CO and PM MACT floor for new fluidized bed units burning biomass/bio-based 

solids, the lowest ranked unit includes tests burning process fuels (deinking residuals). 

The next unit burns a mixture of hog fuel and sludges. The third ranked unit, 

GATempleInlandRome WF was used as the basis of the new source floor. 

2) The TSM8 MACT floor for new fluidized bed units designed to burn biomass fuels is 

based on the third-ranked unit, NDCargillWestFargo Foster Wheeler Boiler (EU43). The 

lowest ranked unit is co-firing natural gas and the second ranked unit fires processspecific fuels. 

3) For the new source HCl floor at liquid fuel boilers, the top ranked unit is firing 

anhydrides waste, a process specific fuel. The floor is based on the second-ranked unit. 
0223.04.020 13

4) The PM and TSM8 MACT floor for new heavy liquid units is based on the second ranked 

unit since the top-ranked unit fires anhydrides waste. 

In addition to these exceptions, the unit with the lowest CO stack test in the coal/fossil solid 

stoker/sloped grate/other subcategory was identified to be a cyclone boiler. This is an old boiler design 

that is no longer being built. As such, it is not representative of the best similar source for this 

subcategory given that this is an ‘other’ type unit and this category is predominantly comprised of stoker 

boilers. The second ranked unit WVDuPontWashingtonWorks, P05, was used as the basis for the new 

source coal/fossil solid stoker/sloped grate/other floor. A cyclone unit design was not identified as a top 

performer for any of the other new source floor analysis. 

Similar to the existing source MACT floor analysis, some subcategories did not have any data available to 

establish a MACT floor and the computed floors from the most similar subcategories were used as a 

proxy to fill these data gaps. 

1) Non-continental liquid: No test data for HCl or TSM8. In these cases the best 

performing unit firing #6 fuel oil was used as a proxy calculation for the non-continental 

liquid subcategory. 

Tables 4 and 5 summarize the MACT floor emission limits for new sources, and the bright yellow 

highlighted cells represent the limits where the corresponding limit for existing sources in the same 

subcategory were used as a basis for the limit at new sources. The UPL floor calculations for each 

subcategory and each pollutant for new sources are shown in Appendix E. 

To assess fuel variability, the same procedures were used; however, only fuel analysis variability 

from the top-performing unit in each subcategory was considered in the analysis. 

Table 4: Summary of MACT Floor Limits for New Boilers and Process Heaters at Major Sources of HAP under Recommended 

Approach 

Subcategory 

Filterable 

Particulate 

Matter 

(lb/MMBtu) 

Hydrogen 

Chloride 

(lb/MMBtu) 

Mercury 

(lb/MMBtu) 

CO 

(ppm @ 3% O2) 

TSM 8 

(lb/MMBtu) 

All Solid Fuels 0.022 8.6E-07

Coal/Fossil Solid

FB 0.0011 17A1.7E-05

PC 0.0013 9

A

2.8E-05

Stoker/Other 0.028 19 2.2E-05

Biomass/Bio-based 
0223.04.020 14

Solid

Dutch Oven/Pile 

Burner 

0.036 810A4.1E-05 

FB 0.0098 230 4.2E-05

Fuel Cell 0.011 210 4.9E-05

Suspension Burner 0.051 58A1.1E-03

Suspension/Grate 0.026 1,500A4.9E-04

Wet Biomass 

Stoker/Other 

0.029 590A2.6E-05 

Dry Biomass 

Stoker/Other 

0.32 250A4.0E-03 

Liquid 0.0012 4.9E-07

Heavy Liquid 0.013 10A9.6E-05

Light Liquid 0.0011 3

A

2.9E-05

Non-Continental 

Liquid 0.008 18A

7.4E-05 

Process Gas 0.0067 0.0017 7.9E-06 4

A

2.4E-04

Notes: 

• Red text indicates at least one test run used to calculate the 99% UPL limit was reported as non-detect data. 

• Blue shaded cells indicate limits that incorporate fuel analysis variability. 

• Yellow shaded cells indicate limits where the calculated limit for new sources was less stringent than the calculated limit for existing 

sources, so the limit for existing sources was used as the basis for the limit at new sources. 

• Green cells indicate limits that are based on the 3*RDL approach. 

• Although default maximum calibration errors were used for CO, if data was flagged as non-detect when initially reported it was still 

considered to be non-detect data even if the value defaulted to the calibration error. 

A CO MACT floor is based on adjusted data that consider measurement error for measurements obtained with an instrument test 

method. 

Table 5: Summary of MACT Floor Limits for New Boilers and Process Heaters at Major Sources of HAP under Alternative 

Approach 

Subcategory 

Filterable Particulate 

Matter 

(lb/MMBtu) 

All Solid Fuels 0.0011

Liquid 0.0013

Notes: 

• All other limits are the same under the alternative approach except for the PM limits in each of the liquid and solid fuel combustorbased subcategories. Under the alternative approach there is no alternative TSM8 emission limit. 

• Red text indicates at least one test run used to calculate the 99% UPL limit was reported as non-detect data. 

Appendix F summarizes all of the variability analysis for new source floor calculations by subcategory. 

3.0 References 

1. Phase I ICR 2008 Combustion Survey. [ICR No. 2286.01]. OMB Control No. 2060-0616 - 

Information Collection Effort for Facilities with Combustion Units. Approved by OMB on August 

1, 2008.
0223.04.020 15

2. Phase II ICR Test Plan Requesting Emission Testing from Boilers, Process Heaters, and CISWI. [ICR 

No. 2286.03]. OMB Control No. 2060-0616 - Information Collection Effort for Facilities with 

Combustion Units. Approved by OMB on May 21, 2009. 

3. Eastern Research Group, Inc. Handling and Processing of Corrections and New Data in the EPA 

ICR Databases-Revised November 2011. 

4. Singleton, A. ERG. Revised MACT Floor Analysis for the Industrial, Commercial, and Institutional 

Boilers and Process Heaters National Emission Standards for Hazardous Air Pollutants – Major 

Source. January 2011. 

5. Eastern Research Group, Inc. Analysis of Dioxin/Furan Data and Minimum Detection Levels from 

Industrial, Commercial, and Institutional Boilers and Process Heaters National Emission 

Standards for Hazardous Air Pollutants – Major Source. November 2011. 

6. Eastern Research Group, Inc. Incorporating Measurement Error in Reported Carbon Monoxide 

(CO) and Total Hydrocarbon (THC) Data (Revised November 2011). 

7. Eastern Research Group, Inc. Summary of Test Report Data Review from Best Performing Units 

at Industrial, Commercial, and Institutional Boilers and Process Heaters National Emission 

Standards for Hazardous Air Pollutants – Major Source. 

8. Emissions Database for Boilers and Process Heaters Containing Stack Test, CEM, & Fuel Analysis 

Data Reported under ICR No. 2286.01 & ICR No. 2286.03 (version 7). November 2011. 

9. Survey Database Containing Results of the 2008 Questionnaire for Boilers, Process Heaters, & 

Other Combustion Units and Supplementary Data Corrections (ICR No. 2286.01 and ICR No. 

2286.03) (version 3). November 2011. 

10. Gibson, G. and A. Singleton, ERG. Revised Standardization of Reported Data from the 

Questionnaire for Boilers, Process Heaters, Incinerators and Other Combustion Units. January 

2011. 

11. Cochran, William G. 1977. Sampling Techniques. Third Edition, John Wiley & Sons. Pages 72-87. 

12. Eastern Research Group, Inc. CO CEMS MACT Floor Analysis (November 2011) for the Industrial, 

Commercial, and Institutional Boilers and Process Heaters National Emission Standards for 

Hazardous Air Pollutants – Major Source. November 2011. 

13. Gibson, G., and A. Singleton, ERG. Revised Standardization of Reported Data from the Public 

Comment Period and Questionnaire for Boilers, Process Heaters, Incinerators and Other 

Combustion Units. January 2011. 

14. Eastern Research Group, Inc. Revised (November 2011) Standardization of Reported Data from 

the Public Comment Period and Questionnaire for Boilers, Process Heaters, Incinerators and 

Other Combustion Units. November 2011. 
0223.04.020 16

15. Eastern Research Group, Inc. Incorporating Measurement Error in Reported Carbon Monoxide 

(CO) Data (Revised November 2011). 

16. Eastern Research Group, Inc. Beyond the Floor Technology Analysis for Major Source Boilers and 

Process Heaters (Revised-November 2011). 
0223.04.020 17

APPENDIX A 

Hg, HCl, and TSM Variability as a Function of Fuel Variability 

(See Excel spreadsheet) 
0223.04.020 18

APPENDIX B 

Ranked Emission Data for MACT Floor Analysis 

(See Excel spreadsheet) 
0223.04.020 19

APPENDIX C 

Upper Prediction Limit (UPL) Calculations for Existing Sources 

(See Excel spreadsheet) 
0223.04.020 20

APPENDIX D 

Summary of Statistical, Fuel, and RDL Variability for Existing Sources 

(See Excel spreadsheet) 
0223.04.020 21

APPENDIX E 

UPL Calculations for New Sources 

(See Excel spreadsheet) 
0223.04.020 22

APPENDIX F 

Summary of Statistical, Fuel, and RDL Variability for New Sources 

(See Excel spreadsheet)