MEMORANDUM

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

FROM: Eastern Research Group, Inc.

DATE: November 20, 2011

SUBJECT: Reconsideration Proposal Baseline Emissions and Emissions Reductions 

Estimates for Existing CISWI Units 

BACKGROUND

The U.S. Environmental Protection Agency, 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, the EPA adopted new source performance standards (NSPS) and emission 

guidelines (EG) for CISWI units under Sections 111 and 129 of the Clean Air Act. In 2001 the 

EPA 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 the EPA’s voluntary remand, 

without vacatur, of the 2000 rule. In 2005, the EPA proposed and finalized the commercial and 

industrial solid waste incineration definition rule which, among other things, revised the 

definitions of "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 

petition[s] 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. 

The development of the MACT floors used to determine proposed emission limits under this 

reconsideration of the final CISWI rules 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 proposed 

standards. 

This memo is organized as follows:
I. Emissions Reductions Summary

II. Baseline Emissions

III. MACT Floor Emissions

IV. Lowest Cost Floor Emissions

I. Emissions Reductions Summary

The current population of CISWI units is estimated to consist of 95 units. This population 

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

implementation of the rule. 

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 proposed 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 34,406 tons per year of 

emissions would be reduced, consisting of 578 tons of HCl, 22,104 tons of CO, 3.09 tons of Pb, 

1.62 tons of Cd, 0.14 tons of Hg, 1,439 tons of PM, 0.0001 tons of PCDD/PCDF, 5,299 tons of 

NOx, and 4,983 tons of SO2. Under the second scenario (Lowest Cost Alternative Emissions 

Reductions), we estimate 34,544 tons per year of emissions would be reduced, consisting of 590 

tons of HCl, 22,069 tons of CO, 3.09 tons of Pb, 1.62 tons of Cd, 0.15 tons of Hg, 1,442 tons of 

PM, 0.0001 tons of PCDD/PCDF, 5,405 tons of NOx, and 5,033 tons of SO2.

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

operating and comply with the proposed 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 proposed 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 proposed MACT floor emissions limits. These were calculated by using the 

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

the proposed 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 proposed 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 proposed 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 proposed 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 proposed 

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 nondigestable 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. 

REFERENCES

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

Reconsideration Proposal” Memorandum from Eastern Research Group, Inc. to Toni Jones, 

U.S. Environmental Protection Agency. November 3, 2011.

2. “Reconsideration Proposal Revised CISWI Control Costs” Memorandum from Eastern 

Research Group, Inc. to Toni Jones, U.S. Environmental Protection Agency. November 20, 

2011.

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)

PCDD/PCDF 

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