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MEMORANDUM 

To: Amy Hambrick, U.S. EPA, Sector Policies and Programs Division/Natural 

Resources and Commerce Group 

From: Eastern Research Group, Inc. 

Date: January 2011

Subject: Revised Cost and Emission Reduction of the MACT Floor Level of Control 

1.0 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 and opacity from existing sewage 

sludge incineration (SSI) units. The nine pollutants are: hydrogen chloride (HCl), carbon 

monoxide (CO), lead (Pb), cadmium (Cd), mercury (Hg), particulate matter (PM), total mass 

basis dioxins/furans (TMB PCDD/PCDF) and toxic equivalency basis dioxin/furans (TEQ 

PCDD/PCDF ), nitrogen oxides (NOx), and sulfur dioxide (SO2). The CAA requires EPA to 

determine the maximum achievable control technology for each subcategory of sources. To do 

so, EPA must first determine the minimum stringency “floor” requirements. A previous 

memorandum documents the MACT floor analysis for SSI units.1 The purpose of this 

memorandum is to present the nationwide costs and nationwide emission reductions estimated 

for existing sources complying with the MACT floor level of control. This memorandum also 

discusses the costs and emission implications of an alternative sewage sludge disposal technique, 

landfilling. This memo is organized as follows: 

2.0 Selecting Controls Needed for Each Unit to Meet MACT Floor Limits 

3.0 Compliance Costs 

 3.1 Emission Control Costs 

 3.2 Stack Testing, Monitoring, and Recordkeeping Costs 

 3.3 Alternative Disposal Costs 

4.0 Emission Reductions 

 4.1 Emissions Reductions based on ‘Actual’ Baseline Estimates 

 4.2 Emissions Reductions based on ‘Potential’ Baseline Estimates 

5.0 References 

6.0 Supporting Tables 

2.0 SELECTING CONTROLS NEEDED FOR EACH UNIT TO MEET MACT 

FLOOR LIMITS 

 A significant portion of the total cost for industry compliance comes from the cost of 

installing new pollution control devices or improving existing pollution control devices for units 

not currently meeting the proposed limits. In order to determine the control costs, it was 

necessary to evaluate, for each SSI unit, how much improvement for each pollutant would be 

needed to meet the proposed emissions limits. 
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The average pollutant concentration values used to calculate baseline annual emissions2

for each unit were compared with the proposed emissions limits, and percentages were calculated 

to quantify the amount of improvement needed for the unit to meet the proposed limits. Tables 

1a and 1b contain the baseline pollutant concentration values used for each unit in each 

subcategory and the percentage improvement required to meet the proposed emissions limits for 

each unit for each pollutant. The existing SSI units are subcategorized into two main groups: 

multiple hearth (MH) units and fluidized bed (FB) units. The pollutant- and subcategory-specific 

limits are shown in each header row of these tables. 

Control methods and cost algorithms utilized in a recent rulemaking for another waste 

combustion source category, Hospital, Medical and Infectious Waste Incinerators (HMIWI) were 

updated and utilized generally for the SSI source category, since most of these algorithms can be 

tailored to the combustion units found in the SSI source category with slight modifications. 

Additional algorithms were obtained from the OAQPS Control Cost Manual. Based on these 

required improvements, pollutant-specific control methods were chosen as follows for units 

requiring more than 10 percent improvement to meet the proposed limits. It was assumed that 

units within 10 percent of the limit would be able to meet the limit by making minor adjustments 

to the unit and/or controls already in place. 

Metals (cadmium and lead) and PM: Adding venturi scrubbers where not already 

installed. If a limit is not met and a venturi scrubber is already installed, a wet electrostatic 

precipitator (WESP) is prescribed. 

Mercury and dioxins/furans (PCDD/PCDF): No further improvement was needed for 

units to meet the MACT floor limit. However, beyond-the-floor options required the addition of 

activated carbon injection (ACI) (in combination with a fabric filter) and adjusting the carbon 

addition rate to meet the amount of reduction required. The costs and emission reductions 

associated with the beyond-the-floor options are discussed in the memorandum “Revised 

Analysis of Beyond the Maximum Achievable Control Technology (MACT) Floor Controls for 

Existing SSI Units.”3 

Hydrogen chloride (HCl): Adding packed bed scrubbers. 

Carbon monoxide (CO): No further improvement was needed for units to meet the 

MACT floor limit. However, beyond-the-floor options required the use of afterburner retrofits 

for units not already having similar control. The costs and emission reductions associated with 

the proposed CO limit are discussed in the memorandum “Revised Analysis of Beyond the 

Maximum Achievable Control Technology (MACT) Floor Controls for Existing SSI Units.”3

Nitrogen oxides (NOx): Adding selective non-catalytic reduction (SNCR) systems. 

Sulfur dioxide (SO2): Adding packed bed scrubbers. 

Further descriptions of these controls and their associated costs are listed below in 

Section 3.0. 

3.0 COMPLIANCE COSTS 

This section presents the nationwide costs estimated for existing SSI for (A) the emission 

controls used to comply with the proposed limits; (B) the monitoring, testing, recordkeeping, and 

reporting activities used to demonstrate compliance; and (C) the alternatives to compliance. 
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Total capital cost for all existing SSI units to meet the proposed MACT floor emission limits is 

estimated at approximately $55.0 million. Total annual cost for controls for all units is about 

$17.8 million/yr. Tables 2a and 2b present detailed costs for emission controls, stack testing, 

monitoring, and reporting and recordkeeping for each unit within each subcategory, as well as 

costs for alternatives to compliance where applicable. Based on these estimates, Table 3 

summarizes two cost scenarios, the first in which all units comply with the proposed emission 

limits, and the second in which large entities comply and small entities shut down their SSIs and 

divert their dewatered sludge to a landfill. Large entities are defined as those for which the 

owner population is greater than or equal to 50,000 people, and small entities are those for which 

the owner population is less than 50,000. Facility owner populations are provided in the SSI 

inventory database memorandum4 and revisions in the database revisions memorandum.5

3.1 Emission Control Costs

Emission control technologies and other control measures that EPA identified that may 

be applicable to comply with the MACT floor options for existing SSI units include packed bed 

scrubbers, venturi scrubbers, wet electrostatic precipitators (WESPs), and selective non-catalytic 

reduction (SNCR). This section presents the costs that were estimated for each of these control 

measures. 

The retrofit factors for the capital costs ranged from 1.2 to 1.4 for considered controls.6

Downtime costs for the retrofits were assumed to be negligible. Most SSI are expected to have 

adequate space to install an emission control system without shutting down the incinerator for an 

extended period. It was also expected that connecting the ductwork could be performed during a 

scheduled downtime for maintenance or during periods of inactivity, thereby minimizing 

expected downtime.7 

The capital and annual costs for the emission controls were estimated in units of dollars 

($) and $/flow. The $/flow costs were calculated by dividing the capital/annual control cost 

estimate for each unit by the average gas flow rate assigned to that unit. 

Total capital cost for controls for all subcategories is estimated at approximately $43 

million, and total annual cost for controls for all subcategories is about $11.0 million/yr. Costs 

are on a 2008 basis, and annualized costs assumed an interest rate of 7 percent. Tables 4a-4e 

present a summary of the parameters and equations used in the cost algorithms for each emission 

control and alternative to compliance where applicable. Tables 5a and 5b lists of the unitspecific inputs for each subcategory used in the algorithms (e.g., incinerator charge rate, stack 

gas flow rate, incinerator operating hours, and concentrations). 

a. Adding a venturi scrubber.

The cost algorithm for installing a venturi scrubber is based on the OAQPS Control Cost 

Manual.6 The venturi scrubber algorithm output is shown in Table 4a, and default values used in 

the algorithm are presented in Table 4b. The VS capital costs range from approximately $71,000 

to $141,000, and annual costs range from approximately $90,000/yr to $169,000/yr. 

b. Adding a packed bed scrubber. 

The cost algorithm for installing a packed-bed wet scrubber is presented in Table 4c and 

is based on algorithms in the Model Plant Description and Control Cost Report for HMIWI.8 
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The packed-bed wet scrubber capital costs range from approximately $375,000 to $4.7 million, 

and annual costs range from approximately $87,000/yr to $1.0 million/yr. Sources for specific 

cost data are noted below Table 4c. 

c. Adding a selective non-catalytic reduction (SNCR) system. 

In an SNCR system, a nitrogen-based reducing agent, or reagent, such as ammonia or 

urea, is injected into the post-combustion flue gas through 3 nozzles mounted on the wall of the 

combustion unit. The cost algorithm for installing an SNCR system is presented in Table 4d and 

is based on algorithms in the OAQPS Control Cost Manual.

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 An SNCR system was costed for 

only one facility (two units), and for each unit the capital cost was approximately $1.2 million 

and the annual cost approximately $133,000/yr. Sources for specific cost data are noted below 

Table 4d. 

d. Adding a wet electrostatic precipitator (WESP). 

The cost algorithm for installing a WESP is presented in Table 4e and is based on 

algorithms in the OAQPS Control Cost Manual.

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 The WESP capital costs range from 

approximately $2.3 million to $2.8 million, and annual costs range from approximately 

$406,000/yr to $499,000/yr. Sources for specific cost data are noted in the source/notes column 

of Table 4e. 

3.2 Stack Testing, Monitoring, and Recordkeeping Costs

Monitoring Costs. Initial and continuous compliance provisions for SSI units were 

selected to be as consistent as possible with proposed commercial and industrial solid waste 

incinerator (CISWI) and current HMIWI provisions. This section presents the costs that were 

estimated for each of these requirements. 

The total capital cost for stack testing, monitoring, and recordkeeping and reporting for 

all subcategories is estimated at approximately $12.0 million, and the total annual cost is about 

$6.8 million per year. Cost estimates were based on algorithms recently utilized in the HMIWI 

regulatory development. Costs were updated to a 2008 basis, and annualized costs assumed an 

interest rate of 7 percent. Tables 6a-6f present a summary of the parameters and equations used 

in the cost algorithms for each monitoring component, where applicable. 

Inspections. Consistent with HMIWI regulations, it was assumed that annual control 

device inspections will be required for any units having control devices in place or requiring 

further controls to meet the proposed emission limits. In this context, control devices include 

fabric filters, afterburners, wet scrubbers, or ACI systems. The cost was estimated at a flat rate 

of $1000 per year. See Table 6a for further details and sources. 

Parameter monitors. Monitoring of operating parameters can be used to indicate whether 

air pollution control equipment and practices are functioning properly to minimize air pollution. 

Based on the existing CISWI regulations and HMIWI regulations, it was assumed that parameter 

monitoring will be mandatory for all units required to add fabric filters, wet scrubbers, or ACI 

systems. Costs for each monitoring system were estimated as follows: 

• For a wet scrubber monitoring system, capital cost was estimated at $24,300 and 

annual cost at $5,600/yr. 
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• For an SNCR monitoring system, capital cost was estimated at $10,300 and annual 

cost at $3,200/yr. 

For default parameters and equations used for monitoring costs, see Table 6b. Sources 

for specific cost data are noted below the table. 

 a. Testing Costs.

1. Initial Stack Testing. It was assumed that initial stack testing will be required 

for each pollutant that the ICR testing showed did not meet the proposed 

emission limit. Any unit having no test data for certain pollutants will also be 

required to perform an initial emissions test for those pollutants. Table 6c 

presents a summary of required initial stack testing for each unit. Costs for 

each required stack test were summed and multiplied by 2/3 to adjust for 

economies of scale when multiple pollutant tests were being performed on a 

unit. The annualized costs were calculated assuming a capital recovery factor 

of 0.10979 (15 years at 7 percent). The basis of these cost estimates for each 

stack test is summarized in Table 6d. 

2. Annual Stack Testing. It was assumed that all units, to some extent, will be 

required to demonstrate ongoing compliance with the emissions limits for all 

pollutants. It was assumed that all units will be required to conduct annual 

stack tests for pollutants if they could not demonstrate the following: 

Metals (Cd, Pb, Hg), PM, CO, HCl, NOX, SO2, PCCD/PCDF: performance at 

or below 75 percent of the MACT standards 

Dioxins/Furans: performance at or below 50 percent of the MACT standards 

It was assumed that units meeting these criteria would need to test only once 

every three years. Using baseline concentrations (the determination of which 

is described in the revised baseline emissions memorandum2), annual testing 

costs were estimated by dividing individual pollutant test costs by 3 where 

these criteria were met. Unit by unit costs are listed in Table 6d. The 

resulting annual average cost for this testing for each unit was estimated to be 

approximately $22,000/yr. 

3. Visible emissions testing. All SSI units will likely have ash handling 

operations. Therefore, these units would be required to demonstrate 

compliance to a 5 percent visible emissions limit for fugitive emissions 

generated during ash handling (similar to HMIWI). We are proposing that 

units will be required to conduct annual performance tests for fugitive 

emissions from ash handling using EPA Method 22. Costs for this annual test 

include a capital cost of $250 and an annual cost of $200, based on the 

Revised Compliance Costs and Economic Inputs for Existing HMIWI memo.8 

Further details regarding this cost estimate are included in Table 6e. 
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b. Recordkeeping and Reporting Costs

For all units, a flat rate of $2,989 per year was estimated as the annual cost for 

recordkeeping and reporting. Further details regarding this cost estimate, including hourly labor 

assumptions, labor rates, and associated sources, are included in Table 6f. 

3.3 Alternative Disposal Costs

Certain SSI units may have waste disposal alternatives other than combustion available to 

them, and these alternatives may prove to be less costly than the controls and monitoring 

required for compliance with the proposed SSI standards. To determine if landfilling would be 

an affordable option for facilities even in the absence of the proposed standards, both the annual 

cost to landfill and the annual unit operating cost were estimated. Then, the overall cost for the 

landfilling option was calculated using the following equation: 

Annual Cost for Landfilling Option = Annual Cost to Landfill – Annual Cost to Operate SSI 

Unit 

Unit-specific operational costs, landfilling cost, and total annual costs for the landfilling 

option are listed in Tables 2a and 2b. The methodology for determining annual landfilling costs 

and annual unit operational costs is described below. 

a. Cost to Haul to Landfill

The cost to haul waste to a landfill is the sum of additional sludge storage costs, landfill 

tipping fees, and transportation costs, which depend on the amount of waste to be hauled and the 

distance traveled per haul. 

If choosing to landfill, it was assumed that a facility would need adequate storage 

capacity to store a minimum of 2 to 4 days worth sludge, to account for occasional multi-day 

landfill closures (e.g. weekends and holidays). Based on feedback from commenters, an average 

capital cost of $30 million was assumed for a facility to construct a sewage sludge storage unit 

with odor control and a truck-loading facility for the sludge. Costs were annualized based on a 

7 percent interest rate and a 30-year lifetime, this yields an annual cost of $2.4 million for the 

storage facility. 

Tipping fees used in the analysis were specific to each state where state data were 

available9; where state data were not available, landfill tipping fees were based on regional 

tipping fees.10 Additional tipping fees provided by commenters on the proposed rules were 

inserted where applicable. All fees were in units of $/ton waste and were converted to 2008 

dollars. The annual tonnage of waste being diverted was calculated based on the wet sludge feed 

rate of each unit and the number of hours it operates per year. Operational hours and sludge feed 

rates are discussed in further detail in the SSI inventory, baseline emissions, and database 

corrections memos. 

Transportation costs were based on an estimated $0.266 per ton-mile11. It was assumed 

that a landfill could be found within 50 miles of each facility, yielding a roundtrip distance of 

100 miles. However, a review of state regulations for states where small entities are located 

revealed that Connecticut and New Jersey do not allow sewage sludge to be landfilled. To adjust 

for this, round trip distances for facilities in these states were increased to 200 miles, assuming a 

landfill could be found in another state within 100 miles from the facility. Additionally, distance 
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information provided by commenters to the proposed rules were incorporated as appropriate into 

the cost calculations. 

Annual landfilling costs varied widely, ranging from $899,000/yr to $17.1 million/yr. 

Table 7a summarizes the parameters and equations used to calculate the annual cost for each 

facility to landfill the waste it would otherwise incinerate in an SSI. 

b. Cost to Operate Incinerator

Annual incinerator operational costs were based on data provided from the ICR survey 

and known unit capacities. The survey specifically requested that respondents provide annual 

costs to operate each incinerator in 2006, 2007 and 2008. Costs were then confirmed or revised 

based on follow-up contact with the survey recipients. Several steps were taken and assumptions 

made to standardize the data: (1) total costs provided were assumed to be for operating only the 

incinerator (i.e. did not include dewatering or other aspects of plant operation); (2) total costs 

listed for multiple units were divided evenly among each unit; and (3) individual cost 

components (e.g. electricity, labor, fuel) were summed if a total cost was not explicitly provided. 

Because cost information was only available for the 9 surveyed entities, an annual cost 

factor, in $/dry ton, was developed using the available data and multiplied by the average 

capacities of all other units. Both an average factor ($179.22/dry ton for FB units and 

$368.45/dry ton for MH units) and a minimum factor ($62.52/dry ton for FB units and 

$87.91/dry ton for MH units) were calculated and applied. The minimum factor is the most 

conservative estimate (i.e. would yield the lowest unit operational cost and thus the highest net 

cost for the landfilling option) and was used for the economic analysis. 

Table 7b summarizes the information provided, assumptions made, and cost factors used 

to estimate costs for all units not having cost data. 

4.0 EMISSION REDUCTIONS 

Emissions reductions were calculated for each of the nine pollutants for two cases: (1) 

using flow rates calculated from actual sludge usage data; and (2) using flow rates calculated 

from sludge capacity. The derivation of these two sets of flow rates is discussed in further detail 

in the database revisions memo.5 Emission reductions were calculated by estimating the 

emissions resulting from each scenario and subtracting the baseline emissions previously 

calculated. The baseline memorandum indicates that emissions and flow rate information was 

collected from only 26 of the 204 SSI units. As described in the baseline memorandum, default 

factors for emissions, flow rate, and sludge capacity were developed and applied to units without 

data. Because the cost to landfill is prohibitively high for most entities, it was assumed all 

entities would choose to comply with the final rules rather than landfilling, and emission 

reductions were not calculated for the alternative disposal scenario described in Section 3.3, 

above. 

4.1 ‘Actual’ Emission Reductions (based on average feed rates) 

Table 8a presents the total expected emissions reductions by subcategory based on flow 

rates derived from actual reported feed rates (see database revisions memorandum5 for more 

information). Details by unit are provided in Tables 9a-9c. Emission reductions were calculated 

using the following equation: 
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Reduction = Baseline – MACT Floor Emission 

The calculation of baseline emissions are described in detail in a separate memo.2 The 

MACT floor emission values, resulting from all entities meeting the proposed limits, were 

calculated as follows: 

a. Units already meeting the proposed limits. 

If a unit was already meeting the MACT floor for a given pollutant, then the MACT floor 

emission value was assumed to equal the baseline value (i.e., no backsliding or emissions 

increases would occur), yielding zero reduction. 

b. Units not currently meeting the proposed limits.

For units not already meeting the MACT floor for a given pollutant, it was assumed that 

with the proposed limits in place the unit would reduce its pollutant concentration to at least that 

of the floor. Thus, the reduction would be the difference between the baseline and the proposed 

limit. 

4.2 ‘Potential’ Emission Reductions (based on maxium feed rates)

‘Potential’ emission reductions were calculated in the same way as ‘actual’ reductions, 

except that flow rates calculated from sludge capacities were used, rather than actual sludge 

usage, in calculating the baseline and MACT floor emissions. Table 8b presents the total 

expected emissions reductions by subcategory based on flow rates derived from unit design 

capacities (see baseline emissions memo for more information). Details by unit are provided in 

Tables 10a-10c. 
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5.0 REFERENCES

1. “Revised MACT Floor Analysis for the Sewage Sludge Incinerator Source Category” 

Memorandum from Eastern Research Group, Inc. to Amy Hambrick, U.S. Environmental 

Protection Agency. 2011. 

2. “Revised Analysis of Beyond the Maximum Achievable Control Technology (MACT) 

Floor Controls for Existing SSI Units” Memorandum from Eastern Research Group, Inc. 

to Amy Hambrick, U.S. Environmental Protection Agency. 2011. 

3. “Revised Estimation of Baseline Emissions From Existing Sewage Sludge Incineration 

Units” Memorandum from Eastern Research Group, Inc. to Amy Hambrick, U.S. 

Environmental Protection Agency. 2011. 

4. “Development of the Inventory Database for the Sewage Sludge Incinerator Source 

Category” Memorandum from Roy Oommen, Eastern Research Group, Inc. to Amy 

Hambrick, U.S. Environmental Protection Agency. June, 2010. 

5. Post-Proposal SSI Database Revisions and Data Gap Filling Methodology. Memorandum 

from Eastern Research Group, Inc. to Amy Hambrick, U.S. Environmental Protection 

Agency. January 2011. 

6. U.S. Environmental Protection Agency. OAQPS Control Cost Manual. Publication 

Number EPA/452/B-02-001. 

7. U.S. Environmental Protection Agency. July 1994. Medical Waste Incinerators--

Background Information for Proposed Standards and Guidelines: Model Plant 

Description and Cost Report for New and Existing Facilities. Publication Number EPA453/R-94-045a. (Docket item no. II-A-112) 

8. Memorandum from Thomas Holloway, RTI, to Ketan Patel, EPA. July 6, 2009. Revised 

Compliance Costs and Economic Inputs for Existing HMIWI. 

9. The State of Garbage in America, Table 4. BioCycle December 2008, Vol. 49, No. 12, 

p. 22. 

10. NSWMA’s 2005 Tip Fee Survey, Table 1. Edward W. Repa, Ph.D. NSWMA Research 

Bulletin, March 2005. 

11. Hauling cost: U.S. Department of Transportation, Research and Innovative Technology 

Administration, Bureau of Transportation Statistics. Table 3-17: Average Freight 

Revenue Per Ton-mile. 
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6.0 TABLES 

The tables referenced throughout the body of this memo are presented in separate MS 

Excel files. They are organized as follows: 

1. Percent Improvement Required to Meet MACT Floor: 

CostandReductionsMemo_Table1.xlsx

1a: Fluidized Bed Units 

1b: Multiple Hearth Units 

2. MACT Floor Costs and Alternative Disposal Costs by Unit: 

 CostandReductionsMemo_Table2.xlsx

2a: Fluidized Bed Units 

2b: Multiple Hearth Units 

3. Summary of MACT Compliance and Alternative Disposal Costs: 

 CostandReductionsMemo_Table3.xlsx 

4. Control Cost Algorithms: 

 CostandReductionsMemo_Table4.xlsx

4a: Venturi Scrubber Algorithm Output 

4b: Venturi Scrubber Defaults 

4c: Packed-Bed Scrubber 

4d: Selective Non-Catalytic Reduction (SNCR) 

4e: Wet Electrostatic Precipitator (WESP) 

5. Input Parameters for Control Cost Algorithms: 

 CostandReductionsMemo_Table5.xlsx

5a: Fluidized Bed Units 

5b: Multiple Hearth Units 

6. Stack Testing, Monitoring, and Recordkeeping Costs: 

 CostandReductionsMemo_Table6.xlsx

6a: Maintenance and Inspection 

6b: Monitoring 

6c: Initial Stack Testing Costs by Unit and Pollutant 

6d: Stack Testing Costs 

6e: Visible Emissions Testing 

6f: Recordkeeping and Reporting 
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7. Alternative Disposal Cost Option: 

 CostandReductionsMemo_Table7.xlsx

7a: Landfill Cost Algorithm 

7b: Reported SSI Operating Costs and Cost Factors 

8. MACT Floor Emission Reductions Summary: 

 CostandReductionsMemo_Table8.xlsx

8a: ‘Actual’ Emission Reductions 

8b: ‘Potential’ Emission Reductions 

9. Emission Reductions by Unit: ‘Actual’ Reductions: 

 CostandReductionsMemo_Table9.xlsx

9a: Emission Reductions 

9b: Baseline Emissions 

9c: MACT Floor Emissions 

10. Emission Reductions by Unit: ‘Potential’ Reductions: 

 CostandReductionsMemo_Table10.xlsx

10a: Emission Reductions 

10b: Baseline Emissions 

10c: MACT Floor Emissions