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MEMORANDUM 

TO: Toni Jones, U.S. Environmental Protection Agency

FROM: Eastern Research Group, Inc. 

DATE: December 12, 2014

SUBJECT: Potential Emission Limits Calculation Analyses for Waste-burning Kilns and 

Coal ERUs 

BACKGROUND

On February 7, 2013, the Environmental Protection Agency (EPA) promulgated its final response 

to petitions for reconsideration of the final new source performance standards and emission 

guidelines for commercial and industrial solid waste incineration units that were promulgated on 

March 21, 2011. Following promulgation of the February 2013 final action, the Administrator 

received petitions for reconsideration that identified issues that petitioners maintain require 

additional reconsideration and/or warrant further opportunity for public comment. 

EPA granted reconsideration of, and requested comment on, the following issues raised: 1) 

Definition of “CEMS data during startup and shutdown periods;” 2) particulate matter (PM) limit 

for the waste-burning kiln subcategory; 3) fuel variability factor for coal-burning energy recovery 

units (ERUs); and 4) the definition of kiln. 

The purpose of this memorandum is to summarize additional data received since the 2013 final 

rule and to present the emission limits that would result if EPA employed the Petitioners’ 

suggested approaches for resolving issues (2) and (3). This memo is organized as follows: 

I. PM Emission Limits for Waste-Burning Kilns 

II. Coal-burning ERU Fuel Variability Incorporation 

a. Incorporating Coal-Only Data 

b. Determining Fuel Variability Factors 

c. Potential Limits for Coal-Burning ERUs 

III. List of Appendices 

I. PM EMISSION LIMITS FOR WASTE-BURNING KILNS

Between the March 2011 final rule and the February 2013 final rule, the inventory of cement 

kilns burning solid waste (i.e. subject to CISWI) fluctuated based on revisions made to the 

NHSM rule. EPA used the same calculation methodology (i.e., the upper prediction limit (UPL) 

calculated from a population of individual test runs) with each iteration of the corresponding 

emissions data. One petitioner argued, however, that the final data set is large enough to warrant 

using 3-run emission test averages as the data population, rather than individual test runs. 

According to the commenter, using this approach to calculate emission limits would result in PM 

emission limits that are different than those of the February 2013 CISWI final rule. 

The PM limit for existing kilns in the 2013 final rule is based on 62 data points – individual runs 

from emissions tests conducted on the three best performing units. The raw data upon which the 
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MACT analysis was based is included here as Appendix A. To develop the potential new PM 

limit for existing units, averages for each of these tests were calculated, yielding a total of 24 data 

points. The 99 percent UPL was calculated using the same equation used previously: 

×
 = ̅ + 
,


 

1



+

1





Where: 

α = the level of significance expressed as a decimal (0.01), note that 100-(α×100) = the 

confidence level (0.99, or 99%); 

 = average or mean of test run data; 

 = t score, the one-tailed t value of the Student’s t distribution for a specific degree of 

freedom and level of significance; 

n = the number of data points; 





 = variance of test run data; and 

 = number of test run values used to calculate the test average. 

In this case, though, n represents the number of averages (24) rather than the number of test runs. 

For the 2013 final limit UPL calculations, m represented the number of observations that would 

be considered in the future for demonstrating compliance; because stack tests generally consist of 

three individual test runs, m was set to equal 3. However, because test run averages are used as 

data points in this potential new approach, m is set equal to 1 in the UPL equation (i.e., there will 

be a single observation, the three-run test average, used in future demonstrations of compliance). 

The UPL calculations are presented in the PM EG tab of Appendix B. The same method was 

applied to develop the potential PM limit for new units, using 10 averages rather than 27 

individual run values for the top performing unit. These calculations are presented in the PM 

NSPS tab of Appendix B. In both cases, the 99% UPL was rounded up to two significant figures. 

The resulting potential test average-based PM emission limits are shown below and compared to 

previous proposed and promulgated limits. 

New or Existing PM 

Limit (units) 

March 

2011 

Final 

Rule 

December 

2011 

Proposed 

Rule 

February 

2013 

Final 

Rule 

Test averagebased 

calculated 

limits 

New Sources PM limit 

(mg/dscm)a

2.5 8.9 2.2 4.9 

Existing Sources PM limit 

(mg/dscm)a

6.2 9.2 4.6 13.5 

a

 Emission limits are expressed as concentrations corrected to 7 percent oxygen. 

II. COAL-BURNING ERU FUEL VARIABILITY INCORPORATION

One petitioner advised EPA of concerns that the derivation of the CISWI limits should take into 

account the variable constituent levels in coal, urging the EPA to incorporate fuel variability into 

the emission limit calculations for coal-fired ERUs as was done in the Boiler MACT. The 

petitioner contended that EPA’s emissions dataset for coal ERUs is very limited for the fueldependent pollutants HCl, Pb, Cd, Hg, and SO2, and that emission standards based on stack test 

and CEMS data alone are too stringent to be met reliably because of the inherent variability of the 

coal. Specifically, they noted that emission standards were based solely on one stack test for Cd, 
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Pb, and HCl, two stack tests for Hg, and seven days of CEMS data for SO2, emphasizing the 

short-term nature of these data. They argued that coal has variable levels of each of these 

contaminants, referencing historical fuel data previously submitted to the Agency during the 

public comment period. 

The petitioner also contended that the data EPA has used to establish the final rule NOx emission 

limit for the best-performing unit in the coal-fired ERU subcategory does not reflect this unit’s 

actual performance accurately, since it reflects only periods of waste combustion in the analysis. 

The petitioner noted that this unit, as well as the other coal-fired ERUs at this facility, operates 

for extended periods of time in a non-waste burning mode. As a remedy, the petitioner suggested 

that EPA use data from both waste-burning and non-waste burning periods for the bestperforming unit to establish MACT floor emission limits, stating that this will more accurately 

reflect actual operating conditions for this unit. 

In response to these concerns, we have conducted analyses to determine what the coal-burning 

emission limits would be if (1) emissions data for both waste and coal-only periods were 

incorporated into the UPL calculations, and (2) if fuel data were used to determine pollutantspecific fuel variability factors (FVFs) to incorporate into the final emission limits. A summary of 

the resulting emission limits is presented in the table below: 

Pollutant 

99% UPL Fuel 

Variability 

Factora

(FVF)

Emission Limitb

Feb 2013 

(Coal-Only Emissions 

data excluded)

Potential 

(Coal-Only Emissions 

data incorporated)

Feb 2013 

Final 

(No FVF) 

Potential 

(UPL*FVF)

Cadmium (Cd) 

(mg/dscm) 0.00946 0.00166 N/A 0.0095 0.0017 

Hydrogen Chloride 

(HCl) (ppmv) 12.49 8.23 7 13 58 

Mercury (Hg) 

(mg/dscm) 0.0160 0.0127 N/A 0.016 0.013 

Lead (Pb) (mg/dscm) 0.1360 0.0394 1.43 0.14 0.057 

Particulate Matter 

(filterable) (mg/dscm) 154 122 N/A 160 130 

Nitrogen Oxides 

(NOx) (ppmv) 331 450.46 N/A 340 460 

a

 Unable to calculate FVF for Cd, Hg, PM, and NOx. FVFs for HCl and Pb are based on maximum ratio in 

data set for coal-only mode of operation. See discussion below for details. 

b

 All emission limits are expressed as concentrations corrected to 7 percent oxygen. 

A. Incorporating Coal-Only Data 

NOx Emissions Data 

The NOx limit in the 2013 final rule is based on NOx CEMS data for Eastman Chemical 

Company’s Boiler 18. The data was from the company’s 2009 ICR response. At the time of 

promulgation, it was the only NOx data in the CISWI database for coal-burning ERUs. Therefore, 

by default, Boiler 18 was ranked as the best-performing unit for NOx.

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Eastman explained in their petitions that their Boilers 18, 19, and 20 only burn solid waste during 

a small percentage of their operating hours. In order to more accurately represent operating 

 

1

 See November 2012 memorandum “CISWI Emission Limit Calculations for Existing and New Sources for the Reconsideration Final 

Rule”(DCN: EPA-HQ-OAR-2003-0119-2662) 
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conditions for these units, they provided EPA with additional NOx CEMS data which 

characterized periods when only coal was combusted as well as periods when both coal and waste 

were being combusted. However, the data was for their Boiler 20, and when the NOx data 

averages were compared, Boiler 18 was still the best performer (i.e. the NSPS and EG limits 

would still be based on the individual run data for Boiler 18). 

Eastman indicated Boiler 20 data should be used in the UPL calculation because the unit is 

identical to Boiler 18 and the two units share the same stack. EPA determined this was not 

appropriate, however, because the emissions were measured at the ductwork from the individual 

units before the combined stack, and therefore the data reflects the performance of the individual 

unit in particular. Eastman therefore submitted additional NOx data for Boiler 18 that includes 

periods of burning coal only from April 17-May 15, 2014. 

The submitted supplemental petitions and NOx data for Boilers 20 and 18 are included as 

Appendices C and D, respectively. 

Coal-Only Emissions Data for Other Pollutants 

The MACT floor calculations used at promulgation excluded emissions data collected during 

periods when no waste was being combusted. For the current effort, we revisited test reports for 

coal-burning ERUs to extract data that reflects periods when only coal was burned. The data 

include emissions concentrations for Cd, HCl, Hg, Pb, and PM for Eastman’s Boilers 19 and 20. 

The additional data are presented in the Data Revisions tab of Appendix E. 

Ranking and Calculating 99% UPL 

Using the same methodology employed at promulgation and incorporating the additional data 

described above, EPA calculated the 99% UPL for Cd, HCl, Hg, Pb, PM, and NOx for coalburning ERUs. Averages for each pollutant for each boiler were calculated in the Data Revisions 

tab of Appendix E, and the units were ranked in the Rankings - ERU - Coal tab of Appendix E. In 

some cases, the best performing units changed. Corresponding UPL calculations are presented in 

Appendix F. Calculations are identical for new and existing units because only one unit 

represents the top 12% of existing units. 

B. Determining Fuel Variability Factors 

FVFs were calculated using a methodology similar to that used for the Boiler MACT. For a given 

pollutant, the following data is needed in order to determine a FVF: 

1. Historical fuel data and fuel data corresponding to the emissions tests of the best 

performer(s) 

2. Fuel data that corresponds to the best performers’ emissions test data 

During the comment period following the 2011 reconsideration proposal, Eastman provided EPA 

with historical fuel analysis data for sulfur, lead, mercury, and chlorine, urging EPA to use the 

data to develop FVFs for SO2, lead, mercury, and hydrogen chloride.2 Eastman acknowledged 

that no cadmium was detected in Eastman’s fuel analyses, therefore no FVF could be determined 

for this pollutant fuel data. 

In additional to the historical fuel data, fuel data specific to the emissions tests of the best 

performer for each pollutant (“paired data”) were identified and extracted from test reports.3 

 

2

 Eastman Chemical Company February 14, 2012 comment letter (DCN: EPA-HQ-OAR-2003-0119-2569) 

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 Blr 19 B-83 Stationary Source Sampling 12-14-05.pdf , Blr 19 B-83 Stationary Source Sampling 3-8 and 9-05.pdf, Blr 20 B-83 
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Because these are multiple-fuel boilers, data corresponding to the predominant fuel (with respect 

to pollutant loading) for each pollutant was selected, and the single highest concentration value 

for a given pollutant was compared to each historical data point using a ratio (the maximum value 

during the emissions testing being the denominator and each historical data point the numerator). 

The next step in the analysis is to identify the historical data points for which this ratio is greater 

than one (i.e. instances where the pollutant concentration in the fuel was higher than the pollutant 

concentration in the fuel during the emissions tests). Any of these ratios greater than or equal to 

the averages of all the ratios plus three standard deviations of all the ratios were removed as 

outliers. The FVF could be calculated based either on the maximum of the remaining ratios or the 

mean of the remaining ratios. For the purposes of this analysis, the maximum ratio was selected 

to develop a potential FVF. 

FVF calculations and data sources are presented the individual pollutant tabs of Appendix G. 

Based on available data, FVFs were calculated for two pollutants, HCl and Pb. No FVFs were 

determined for Hg, Cd, PM, NOx, or SO2 for the following reasons: 

Mercury. There were only two instances where the ratio of historical data to paired data 

was greater than one, and these two data points were outliers. Therefore, no FVF could be 

determined for mercury. 

Cadmium. As noted above, fuel data was all non-detect for this pollutant. 

Particulate Matter. No paired or historical fuel data available. 

Nitrogen Oxides. No paired or historical fuel data available. 

Sulfur Dioxide. Although percent sulfur was included in the historical fuel data provided 

by Eastman, only one fuel data point was available to be paired with SO2 emissions data. 

Eastman claimed they supplied 4 values for percent sulfur that could be paired with 30 

days of SO2 data they’d also submitted. However, that CEMS data corresponded to their 

coal-fired boilers, not the three CISWI units (Boilers 18, 19, and 20).Therefore, no FVF 

was determined. 

C. Potential Limits for Coal-Burning ERUs 

The potential new limits for coal-burning ERUs were calculated by multiplying the revised UPL 

values (discussed in II.A above) by the calculated FVFs (discussed in II. B, above), where 

applicable. If no FVF was determined, the potential limit is simply the UPL rounded up to the 

nearest two significant figures. Where FVFs were calculated, the product of the UPL and FVF is 

rounded up to the nearest two significant figures. 

Revised 99% UPL values, FVFs, and all potential limits (including those if the FVF is based on 

an average ratio) are presented in the Summary tab of Appendix G. 

III. LIST OF APPENDICES

Appendix A KilnEmissionsData.xlsx 

Appendix B Existing Kilns PM Variability With Run Averages.xlsx 

Appendix C Eastman Boiler 20 NOx Data May-June 2013.xlsx 

Appendix D Eastman Boiler 18 NOx Data April-May 2014.xlsx 

Appendix E Rankings_IncludingCoal-OnlyData.xls 

Appendix F VariabilityAnalysis - ERU - Coal - IncludingCoal-OnlyData.xls 

 

Stationary Source Sampling Report 11-30 and 12-1-04.pdf available within DCN EPA-HQ-OAR-2003-0119-0047. 
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Appendix G FVFCalcs.xlsx