MEMORANDUM

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

FROM: Eastern Research Group, Inc.

DATE: November 26, 2012

SUBJECT: Final Reconsideration Baseline Emissions and Emissions Reductions Estimates 

for Existing CISWI Units 

BACKGROUND

The U.S. Environmental Protection Agency (EPA), under section 129 of the Clean Air Act 

(CAA), is required to regulate emissions of nine pollutants from Commercial and Industrial Solid 

Waste Incineration (CISWI) units: hydrogen chloride (HCl), carbon monoxide (CO), lead (Pb), 

cadmium (Cd), mercury (Hg), particulate matter (PM), dioxins/furans (PCDD/PCDF), nitrogen 

oxides (NOx), and sulfur dioxide (SO2).

On December 1, 2000, EPA adopted new source performance standards and emission guidelines 

for commercial and industrial solid waste incineration units established under Sections 111 and 

129 of the Clean Air Act. In 2001 EPA was granted a petition for reconsideration regarding the 

definitions of "commercial and industrial waste" and "commercial and industrial solid waste 

incineration unit." In 2001, the United States Court of Appeals for the District of Columbia 

Circuit granted EPA’s voluntary remand, without vacatur, of the 2000 rule. In 2005, EPA 

proposed and finalized the commercial and industrial solid waste incineration definition rule 

which revised the definitions of “solid waste,” “commercial and industrial waste,” and 

“commercial and industrial waste incineration unit.” In 2007, the United States Court of Appeals 

for the District of Columbia Circuit vacated and remanded the 2005 commercial and industrial 

solid waste incineration definition rule.

On March 21, 2011, the EPA promulgated revised NSPS and EG as its response to the voluntary 

remand that was granted in 2001 and the vacatur and remand of the commercial and industrial 

solid waste incineration definition rule in 2007. In addition, the standards re-development 

included the 5-year technology review of the new source performance standards and emission 

guidelines required under Section 129. Following that action, the Administrator received 

petitions for reconsideration and identified some issues that warranted further opportunity for 

public comment. In addition, data were received that enabled the EPA to revise the CISWI 

inventory of waste-burning kilns and energy recovery units to more accurately reflect the 

definition of non-hazardous secondary materials. On December 23, 2011, the EPA published 

proposed amendments that incorporated these changes and allowed public comment on specific 

issues identified for reconsideration. The development of the MACT floors used to determine 

these options is discussed in more detail in a separate memorandum.

1 The purpose of this 

memorandum is to present baseline emissions estimates for existing sources and anticipated 

emissions reductions that would result from compliance with the final standards. 

This memo is organized as follows:

I. Emissions Reductions Summary
II. Baseline Emissions

III. MACT Floor Emissions

IV. Lowest Cost Floor Emissions

V. New Sources

I. Emissions Reductions Summary

The current population of CISWI units is estimated to consist of 106 units. This population 

represents the estimate of CISWI units that would still be burning waste materials upon 

implementation of the rule. Waste-burning kilns that are considered "waste-burning” solely due 

to burning whole tires are assumed to be able to find a source of whole tires that would not be 

considered a waste (whole tires obtained from approved tire management programs and tirederived fuel from which the metal has been removed are not considered solid waste under the 

definition of solid waste) prior to implementation, and would thus be subject to the provisions of 

the Portland Cement NESHAP instead of CISWI. 

Emissions reductions for the CISWI units were calculated for each of the nine pollutants (plus 

particulate matter less than 2.5 microns (PM2.5)) for two scenarios: 1) Assuming each existing 

unit complied with the final emissions limits, and 2) Assuming that units would comply using the 

lowest cost alternative, either complying with the emission limits or ceasing to use the 

combustion device and utilizing less costly alternatives, such as landfilling solid waste materials.

Under the first scenario (MACT Floor Emission Reductions), we estimate 34,771 tons per year of 

emissions would be reduced, consisting of 772 tons of HCl, 20,093 tons of CO, 2.5 tons of Pb, 

1.8 tons of Cd, 0.34 tons of Hg, 2,397 tons of PM, 0.00006 tons of PCDD/PCDF, 5,292 tons of 

NOx, and 6,211 tons of SO2. Under the second scenario (Lowest Cost Alternative Emissions 

Reductions), we estimate 34,909 tons per year of emissions would be reduced, consisting of 784

tons of HCl, 20,058 tons of CO, 2.5 tons of Pb, 1.8 tons of Cd, 0.34 tons of Hg, 2,401 tons of PM, 

0.00006 tons of PCDD/PCDF, 5,399 tons of NOx, and 6,262 tons of SO2.

Table 1 presents the anticipated emissions reductions by subcategory assuming all units remain 

operating and comply with the final emission limits. Table 2 presents the anticipated emissions 

reductions by subcategory assuming units either comply or cease operation and use alternative 

disposal methods, depending on which option costs less. Table 2 also includes estimates of 

secondary air emissions that would result from landfilling the diverted waste materials and flaring 

the landfill gas that these wastes would generate.

II. Baseline Emissions

Baseline emissions represent the estimated annual emissions of existing units prior to retrofit of 

controls to comply with the final emission limits. 

Calculation Methodology. Annual emissions estimates are calculated using the pollutant 

concentration (mass per stack gas volume) multiplied by the flue gas flow rate (dry standard 

cubic feet per minute) and the time (hours per year) the unit is operated. Appendix A presents the

calculations needed to convert from the standard pollutant concentrations to the annual tons 

emitted.

Pollutant Concentration data. Pollutant concentration data measured from emissions tests for the 

unit were used whenever available. When there were data gaps, these were filled first by using 
the same measured data from similar units operated by the corporate entity. If these data were not 

available, then subcategory default values were assigned for the unit. These default values were 

the mean of the actual emissions test values measured for the units within a subcategory.

Flue Gas Flow Rate and Operating Hours. The flue gas flow rate and annual operating hours 

used to calculate emissions were similar to those that were used as inputs for control costing 

algorithms. Each unit’s baseline emissions are based on unit average test data for each pollutant. 

Actual emissions test data and survey data from the CISWI database were used whenever 

available. Similar unit values were used if there were any data gaps for a similar unit operated by 

the entity. Lastly, F-factor estimates or subcategory default values were applied as necessary to 

fill in the remaining gaps in flue gas flow rates. The flue gas flow rate data gap filling procedures 

are discussed in more detail in the control costing memorandum.2

 

Table 3 presents the baseline concentration, hours of operation, stack gas flow rate, and annual 

emissions estimates for each of the CISWI units.

III. MACT Floor Emissions

MACT floor emissions are the estimated annual emissions that would result from CISWI units 

complying with the MACT floor emissions limits. These were calculated using the same 

equations that were used for the baseline emissions that are listed in Appendix A. However, the 

final MACT floor emissions limit is used as the pollutant concentration if the baseline 

concentration exceeds the final limit value. If a unit’s baseline pollutant concentration is below 

the final emissions limit, then that concentration was used to calculate the MACT floor emissions 

as well (i.e., no backsliding or emissions increases would occur). Additionally, for units expected 

to require the addition of fabric filters to meet one or more pollutant limits, a reduction efficiency 

of 99% was applied to their baseline values for Cd, Pb,and PM to determine their MACT floor 

emissions for these pollutants to fully account for the co-control for all of these pollutants due to 

the addition of a high-efficiency fabric filter.

Table 4 presents the estimated MACT floor emissions for each unit as described above. Hours of 

operation and stack gas flow rates used to determine tons per year are also included. Table 5 puts 

the baseline and MACT floor emissions estimates together and presents the annual emissions 

reductions for each CISWI unit. 

Table 5 also presents the amount of PM2.5 emissions reduction anticipated for each unit. These 

emissions are calculated as a percent of the PM filterable emissions reductions. These fractions 

were based on emission factors from EPA’s AP-42 document3

, and are a function of the materials 

burned and the baseline control devices (if any) present on the unit. These PM2.5 fraction factors 

are presented in Appendix B.

IV. Lowest Cost Floor Emissions

Two of the CISWI subcategories have potential alternatives to incineration that could be more 

economical than complying with the final CISWI standards. The incinerator and small, remote 

incinerator subcategories could cease to burn solid waste and instead divert this waste to a landfill 

for disposal. The costs of complying with the rule and those associated with these disposal 

alternatives are discussed in more detail in the control costing memorandum.2

 The cost estimates 

indicate that all but three of the incinerators would cease using the combustion unit and use 

alternative disposal rather than adding controls necessary to comply with the final standards. The 
three incinerators that would likely remain operating are ILFlintHillsResources MB-1012, 

LAShellChemical F-T701, and SCEastmanColumbia 1560-0008 ID #15. For the small remote 

subcategory, we estimate that no units would shut down, but that for many units it would be less 

expensive to segregate their waste and divert the nonferrous metal and chlorinated plastic to a 

landfill, rather than install the controls necessary to comply with the limits if no waste segregation

were being practiced. This is possible for this particular subcategory since the waste these units 

are burning is primarily municipal-type waste from industrial sites, which is usually able to be 

segregated for recyclable materials. The waste segregated out is assumed to be non-digestable or 

minimally digestible materials such as ferrous and non-ferrous metals and PVC, and therefore 

would not contribute significantly to landfill gas emissions. By removing these materials from 

the waste stream, it is expected that these small remote units will be able to meet the 

PCDD/PCDF and Hg MACT floor limits. 

When incinerators cease combusting waste, the waste that is diverted to a landfill will generate 

landfill gas (methane, carbon dioxide, hydrogen sulfide, chlorine gas, and other trace 

constituents). This waste may likely be combusted by a landfill flare, which would generate 

some emissions. These landfill flare emissions would be considered a secondary air impact to the 

final CISWI rule, since the waste that generates the landfill gas was diverted to the landfill due to 

the rule. The potentially diverted waste estimates are presented in the control costing 

memorandum2

, but were estimated based on the unit’s waste combustion capacity and the annual 

operating hours. The waste diverted estimates were then assumed to be steady for 20 years (the 

expected useful life of a CISWI unit) to calculate estimates of the landfill gas generated from the 

diverted waste. These estimates were calculated using a first-order decay model (EPA’s Landfill 

Gas Emissions Model (LandGEM) Version 3.02).4

 Then, LandGEM default landfill gas sulfur 

and chlorine concentrations, along with landfill gas flare emissions factors from EPA’s AP-42 

were then used to calculate annual secondary air impact emissions from the landfilling of the 

diverted solid waste. The LandGEM model inputs, flare emission factors, and calculated 

emissions are presented in Appendix C. These emissions were then subtracted from the total 

emission reductions to get an adjusted annual emissions reduction in Table 2. 

V. New Sources

While we do not anticipate any new energy recovery units or waste-burning kilns to be 

constructed, it is conceivable that some new incinerator and small, remote incinerator units will 

be installed in the future to replace aging units or to service new facilities. It was assumed that 

one new incinerator would come into operation over the next five years. We anticipate three new 

small, remote units to come online next year and one new small, remote unit to be constructed 

each subsequent year. Please see the CISWI compliance cost memo for additional details 

regarding new source assumptions. 2

In order to determine the expected emission reductions resulting from NSPS compliance, average 

uncontrolled emissions resulting for each pollutant were calculated using default control 

efficiencies in conjunction with the average baseline concentrations for each unit and its 

corresponding controls. Calculations can be found in the CISWI compliance cost memo.2 These 

values were compared with NSPS emission limits and reductions were calculated following the 

method described above for existing units. 

Emission reductions for incinerators and small, remote incinerators are presented in Table 6. The 

reductions are presented on a per-unit basis. For each new incinerator, we estimate 122 tons per 

year of emissions would be reduced, consisting of 2.6 tons of HCl, 0.56 tons of Pb, 0.14 tons of 

Cd, 0.0026 tons of Hg, 102.7 tons of PM, 0.0000005 tons of PCDD/PCDF, 11.3 tons of NOx, and 
5.1 tons of SO2. No significant reduction for CO is anticipated because data from existing units 

suggest new units will be able to meet the CO limit without additional add-on controls. For each 

new small, remote unit, we estimate 22 tons per year of emissions would be reduced, consisting 

of 0.11 tons of Pb, 0.02 tons of Cd, 6.7 tons of CO, 0.0004 tons of Hg, 10.7 tons of PM, and 4.5 

tons of SO2. No reductions were calculated for HCl, NOx, and PCDD/PCDF because data from 

existing units suggest new units will be able to meet these limits without additional add-on 

control.

REFERENCES

1. “CISWI Emission Limit Calculations for Existing and New Sources for the Reconsideration 

Final Rule” Memorandum from Eastern Research Group, Inc. to Toni Jones, U.S. Environmental 

Protection Agency. November 16, 2012.

2. “Final Reconsideration Compliance Cost Analyses for CISWI Units” Memorandum from 

Eastern Research Group, Inc. to Toni Jones, U.S. Environmental Protection Agency. November 

26, 2012.

3. U.S. EPA. Compilation of Air Pollutant Emission Factors, Vol. 1. (AP-42) Fifth Edition. 

1995.

4. U.S. EPA Office of Research and Development. Landfill Gas Emissions Model (LandGEM) 

Version 3.02. May 2005.
APPENDIX A

CONVERSION CALCULATIONS

The following calculations were used to develop ton/year emission estimates:

PM, Pb, Cd and Hg

Concentration ”X” given in mg/dscm, flow rate ”FR” in dscf/minute (dscfm), and annual 

hours ”H” (hours/year):

[X(mg/dscm) x FR(dscf/min) x 60(min/hr) x H(hr/year)] ÷

[35.3147(dscf/dscm) x 453,592(mg/lb) x 2,000(lb/ton)] = (ton/yr)

CDD/CDF 

Concentration ”X” given in ng/dscm, flow rate ”FR” in dscf/minute (dscfm), and annual 

hours ”H” (hours/year):

[X(ng/dscm) x FR(dscf/min) x 60(min/hr) x H(hr/year)] ÷

[35.3147(dscf/dscm) x 1,000,000 (ng/mg) x 453,592(mg/lb) x 2,000(lb/ton)] = (ton/yr)

HCl, NOx, SO2, CO 

Concentration ”X” given in ppmvd, flow rate ”FR” in dscf/minute (dscfm), annual hours ”H” 

(hours/year), and molecular weight ”MW” as follows: HCl = 36.45, NOx = 46, SO2 = 64.06, 

CO = 28.01:

[X(ppmvd) x MW(lb/lbmol) x FR(dscf/min) x 60(min/hr) x H(hr/year)] ÷

[1,000,000 x 385.5(dscf/lbmol) x 2,000(lb/ton)] = (ton/yr)
APPENDIX B

PM2.5 FRACTION INFORMATION
APPENDIX C

LANDFILL GAS AND FLARE EMISSIONS ESTIMATES