EPA

Office of Air Quality

Pla nnin g a nd S ta nd a rds

C Air

lean

United States Office of Air Quality EPA-453/R-00-001

Environmental Protection Planning and Standards June 2000

Agency Research Triangle Park, NC 27711

Small Municipal Waste Combustors:

Background Information Document for 

New Source Performance Standards and

Emission Guidelines 

Public Comments and Responses
0085-00-046-003

SMALL MUNICIPAL WASTE COMBUSTORS:

BACKGROUND INFORMATION DOCUMENT 

FOR NEW SOURCE PERFORMANCE STANDARDS 

AND EMISSION GUIDELINES

PUBLIC COMMENTS AND RESPONSES

U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Emission Standards Division

Research Triangle Park, North Carolina 27711

June 2000
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ii
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TABLE OF CONTENTS

Section Page

1.0 INTRODUCTION ....................................................... 1

2.0 PUBLIC COMMENTS AND 

ORGANIZATION OF THIS DOCUMENT .................................... 3

2.1 LIST OF ACRONYMS AND ABBREVIATIONS ....................... 10

3.0 COMMENTS ON NEW SOURCE PERFORMANCE STANDARDS (NSPS) ....... 13

3.1 SELECTION OF SOURCE CATEGORY .............................. 13

3.2 SELECTION OF AFFECTED FACILITIES ............................ 14

3.3 SELECTION OF THE MAXIMUM ACHIEVABLE CONTROL TECHNOLOGY

(MACT) ........................................................ 15

3.3.1 General Comments on Emission Levels ............................ 15

3.3.2 Municipal Waste Combustor Organics ............................ 15

3.3.3 Municipal Waste Combustor Metals (Mercury) ..................... 16

3.3.4 Nitrogen Oxides ............................................. 16

3.3.5 Good Combustion Practices .................................... 17

3.3.6 Size Categories of New Municipal Waste Combustor Units ............ 18

3.4 PERFORMANCE TEST METHODS AND MONITORING ............... 19

3.4.1 Continuous Monitoring ........................................ 19

3.4.2 Test Methods ............................................... 21

3.5 STARTUP, SHUTDOWN, AND MALFUNCTION ...................... 25

3.6 LEGAL CONSIDERATIONS ....................................... 26

4.0 COMMENTS ON THE EMISSION GUIDELINES ............................ 33

4.1 SELECTION OF SOURCE CATEGORY .............................. 33

4.2 SELECTION OF DESIGNATED FACILITIES .......................... 34

4.3 SELECTION OF MAXIMUM ACHIEVABLE CONTROL TECHNOLOGY . . 37

4.3.1 General Comments on Emission Levels ............................ 37

4.3.2 Municipal Waste Combustor Organics ............................ 41

4.3.3 Municipal Waste Combustor Metals (other than Mercury) 

and Particulate Matter ........................................ 42

4.3.4 Nitrogen Oxides Emission Limit ................................. 42

4.3.5 Good Combustion Practices .................................... 44

4.3.6 Size Categories of Existing MWC Units ........................... 48

4.3.7 Classes of Existing MWC Units ................................. 49

4.4 IMPACTS OF MUNICIPAL WASTE COMBUSTOR EMISSION 

GUIDELINES ................................................... 51
iv

TABLE OF CONTENTS (Continued)

Section Page

4.5 PERFORMANCE TEST METHODS AND MONITORING PROVISIONS 

FOR MUNICIPAL WASTE COMBUSTOR EMISSIONS ................. 53

4.5.1 Continuous Monitoring ........................................ 53

4.5.2 Comments on Test Methods .................................... 60

4.6 ENFORCEMENT, REPORTING, AND RECORDKEEPING PROVISIONS . . 67

4.6.1 Enforcement ................................................ 67

4.6.2 Recordkeeping and Requirements ................................ 69

4.7 LEGAL CONSIDERATIONS ....................................... 69

4.8 COMPLIANCE SCHEDULES ....................................... 78

5.0 MISCELLANEOUS COMMENTS ON MUNICIPAL WASTE COMBUSTOR

EMISSIONS GUIDELINES ............................................... 81

5.1 DETERMINING MWC UNIT CAPACITY ............................. 81

5.2 STATE PLANS .................................................. 81

5.3 FEDERAL REGISTER PRINTING ERROR............................. 82

5.4 PUBLIC HEARING REQUIREMENT ................................ 82

5.5 IMPLEMENTATION .............................................. 83

5.6 TITLE V PERMITS ............................................... 83

5.7 DELEGATION ................................................... 84

6.0 ADMINISTRATIVE REQUIREMENTS ..................................... 85

6.1 EXECUTIVE ORDER 12866 ........................................ 85
1

1.0 INTRODUCTION

On August 30, 1999, the U.S. Environmental Protection Agency (EPA) proposed regulations

to: (1) reestablish new source performance standards (NSPS) for new small municipal waste

combustion (MWC) units, and (2) reestablish emission guidelines for existing small MWC units. These

proposals were made under authority of Sections 129 and 111 of the Clean Air Act (CAA). The

NSPS and emission guidelines for small municipal waste combustors were originally adopted in

December 1995, but were vacated (canceled) by the U.S. Court of Appeals for the District of

Columbia Circuit in March 1997. The vacature was based on the court’s opinion that the CAA of

1990 requires EPA to establish separate regulations for large and small MWC units and that EPA had

inappropriately placed small MWC units located at MWC plants larger than 250 tons per day (tpd) in

the large MWC category. The court’s opinion did not identify other errors in the 1995 MWC rules. 

Additionally, the court indicated they expected EPA to reestablish the regulation for small MWC units

in an inspired fashion. On August 30, 1999, EPA proposed to reestablish NSPS and emission

guidelines for small MWC units. The NSPS and emission guidelines proposed on August 30, 1999

were functionally equivalent to the 1995 NSPS and emission guidelines for small MWC units. 

This document contains summaries of the public comments that EPA received on the August

30, 1999 proposal to reestablish NSPS and emission guidelines, and EPA’s responses to those

comments. This summary of comments and responses serves as the basis for revisions made to the

NSPS and emission guidelines between proposal and promulgation. 
2

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1

 Municipal Waste Combustion: Background Information Document for Promulgated

Standards and Guidelines - Public Comments and Responses (EPA-453/R-95-0136, Docket No. A90-45) (1995 BID).

3

2.0 PUBLIC COMMENTS AND 

ORGANIZATION OF THIS DOCUMENT

In the 1995 rulemaking for MWC units, EPA received 153 letters (approximately 2,000 pages)

commenting on the NSPS and emission guidelines. Those comments are summarized in the

1995 background information document.1 In the current rulemaking, EPA received 48 letters

(approximately 350 pages) and heard seven speakers at the public hearing on the proposal (the public

hearing occurred October 5, 1999). The commenters, speakers, and their affiliations are listed in Table

2-1.

Many of the comments received on the standards and guidelines are similar to comments

received on the 1994 proposal to establish standards and guidelines. Therefore, this document is

organized similarly to the 1995 BID. Comments and responses on the NSPS appear first

(Section 3.0), followed by comments and responses to the emission guidelines (Section 4.0). Section 5

includes miscellaneous comments on the emission guidelines. Where similar comments are discussed in

the 1995 BID, the 1995 BID is referenced at the end of the comment response (e.g., See Section 3.1

of 1995 BID). 
4

TABLE 2-1. DOCKET A-98-18 (See Note A)

CATEGORIES: IV-D, IV-F and IV-G

Item Number Commenter and Affiliation

IV-D-01 H. G. Rigo, President

Rigo & Rigo Associates, Inc., 

Berea, OH

IV-D-02 L.S. Jenkins, Counsel 

Wood Crapo

Comments of the Davis County Solid Waste Management and Energy Recovery

Special Service District

Salt Lake City, UT

IV-D-03 D.A. Lue, Environmental Coordinator

Montenay International Corp., 

Miami FL

IV-D-04 D. R. Lispi

Assistant to the Mayor for Special Projects

City of Harrisburg

Harrisburg, PA

IV-D-05 M. Graham, Private Citizen 

Layton, UT

IV-D-06 D. K. Mount, Director

Division of Environmental Engineering 

North Dakota Department of Health

Bismarck, ND

IV-D-07 J. Rossman, Chairperson, Olmsted County Board of Commissioners, and R.

Dunnette, Plant Manager 

Olmsted Waste to Energy Facility 

Olmsted County 

Rochester, MN

IV-D-08 R. D. Randolph, Director 

Air Pollution Control Program

Missouri Department of Natural Resources

Jefferson City, MO

Note A: Docket A-98-18 for this rulemaking is located at EPA’s Air and Radiation Docket and

Information Center (MC-6102), 401 M Street SW., Washington, DC 20460, Room M-1500, Waterside

Mall (ground floor, central mall). The docket is available for public inspection and copying between

8:00 a.m. and 5:00 p.m., Monday through Friday. A reasonable fee may be charged for copying.
TABLE 2-1. DOCKET A-98-18 (CONTINUED)

CATEGORIES: IV-D, IV-F and IV-G

Item Number Commenter and Affiliation

5

IV-D-09 M. Graham, Private Citizen

Layton, UT 

IV-D-10 J. S. Austin, Steam Plant, Manager

Hampton/NASA Refuse-Fired Steam Plant

Hampton, VA

IV-D-11 T. J. Porter, Director Air Quality

Wheelabrator Technologies, Inc., 

Hampton, NH

IV-D-12 E. Eckels, Private Citizen

IV-D-13 J. M. Daniel, Director

Division of Air Program Coordination 

Virginia Department of Environmental Quality

 Richmond, VA

IV-D-14 J. Veranth, Research Assistant

Professor of Chemical Engineering

University of Utah 

Salt Lake City, UT

IV-D-15 M. Graham, Private Citizen

Layton, UT 

IV-D-16 U. Kramer, Executive Secretary

Utah Air Quality Board

Utah Department of Environmental Quality 

Salt Lake City, UT

IV-D-17 J. Skinner, Executive Director & CEO

Solid Waste Association of North America 

Silver Spring, MD

IV-D-18 J. Freeland, Counsel

Matthews & Freeland 

Comments of City of Cleburne

Austin, TX

IV-D-19 M. Graham, Private Citizen

Layton, UT
TABLE 2-1. DOCKET A-98-18 (CONTINUED)

CATEGORIES: IV-D, IV-F and IV-G

Item Number Commenter and Affiliation

6

IV-D-20 J. L. Barlow, President 

The Barlow Group, Inc., 

Fort Collins, CO

IV-D-21 R. S. Broom and S.R. Johnson, Counsel

Dutchess County Resource Recovery Agency 

Verner Liipfert Bernhard McPherson and Hand

Washington, DC

IV-D-22 E.J. Campobenedetto, Deputy Director 

Institute of Clean Air Companies 

Washington, DC 

IV-D-23 D. Kaplan, Counsel

Earthjustice Legal Defense Fund 

Washington, DC

IV-D-24 D. Kaplan, Counsel

Earthjustice Legal Defense Fund 

Washington, DC

IV-D-25 E.J. Campobenedetto, Deputy Director

Institute of Clean Air Companies

Washington, DC

IV-D-26 K. Van Dame 

Wasatch Clean Air Coalition

Salt Lake City, UT

IV-D-27 J. A. Musso, General Manager

Environmental Affairs and Lands

Northern States Power Company 

Eau Claire, WI

IV-D-28 T.M. Cantrell, Private Citizen 

IV-F-1a William R. Steinhaus 

County Executive of Dutchess County New York

Poughkeepsie, NY (presented by Scott Daniels)

IV-F-1b Scott Daniels, Executive Director

Dutchess County Resource Recovery Agency, and Commissioner Dutchess

County Department of Solid Waste Management Poughkeepsie, NY
TABLE 2-1. DOCKET A-98-18 (CONTINUED)

CATEGORIES: IV-D, IV-F and IV-G

Item Number Commenter and Affiliation

7

IV-F-1c Eric Hofmeister, President

Islip Resource Recovery Agency 

Islip, NY

IV-F-1d John L. Rose, Consulting Engineer 

Dutchess County Resource Recovery Agency and Islip Resource Recovery

Agency

IV-F-1e Mark L. Wollschlager, Senior Vice President

HDR Engineering

IV-F-1f H. Gregor Rigo, President, 

Rigo & Rigo Associates, Inc., 

Berea, OH

IV-F-1g Maria Zannes, President

Integrated Waste Services Association

Washington, DC 

IV-G-01 T. J. Richter, Executive Director

Minnesota Resource

Recovery Association 

St. Paul, MN

IV-G-02 R. E. Brown, General Manager

Resource Authority

Gallatin, TN

IV-G-03 B. Mathur, Chief

Illinois Environmental Protection Agency

Springfield, IL

IV-G-04 J. J. Poulton, General Manager

Waste Energy Partners, LP

Joppa, MD

IV-G-05 D. A. Lue, P.E. 

Environmental Coordinator Monetary International Corp

Miami, FL

IV-G-06 H. G. Rigo, President

Rigo & Rigo, Associates, Inc. 

Berea, OH
TABLE 2-1. DOCKET A-98-18 (CONTINUED)

CATEGORIES: IV-D, IV-F and IV-G

Item Number Commenter and Affiliation

8

IV-G-07 W. Strandell, Chairperson,

Polk County Board of Commissioners, & B. Wilson

Facilities Manager 

Polk County Resource Recovery Plant

Crookston, MN

IV-G-08 D. Kaplan

Earthjustice Legal Defense Fund 

Washington, DC

(letter not included in original comment)

IV-G-09 D.Kaplan

Earthjustice Legal Defense Fund

Washington, DC

IV-G-10 T. J. Porter

Director Air Quality

Wheelabrator Technologies (fax)

IV-G-11 H. G. Rigo, President

Rigo & Rigo, Associates, Inc. 

Berea, OH

IV-G-12 K. Solbert, Advisory Board, Chair

R. Andring, Commissioner

J. Dahl, Commissioner 

J. Heltzer, Commissioner 

Clearwater County Environmental Services 

Bagley, MN (letter in support of IV-G-07)

IV-G-13 Shirley Holman, Chair

LaCrosse County Solid Waste Committee

LaCrosse County, WI 

IV-G-14 Frank J. Visser, Deputy Superintendent

Energy Recovery Facility

County of Oswego

Fulton, NY

IV-G-15 James A. Musso, General Manager

Environmental Affairs and Lands

Northern States Power Co.

Eau Claire, WI
TABLE 2-1. DOCKET A-98-18 (CONTINUED)

CATEGORIES: IV-D, IV-F and IV-G

Item Number Commenter and Affiliation

9

IV-G-16 Mark Graham, Private Citizen

Layton, UT

IV-G-17 D. A. Lue, P.E., Environmental Coordinator

Montenay International Corp.

Miami, FL
10

2.1 LIST OF ACRONYMS AND ABBREVIATIONS

Acronyms

1995 BID Municipal Waste Combustion: Background Information Document for

Promulgated Standards and Guidelines - Public Comments and Responses,

EPA-453/R-95-0136

Administrator EPA Administrator

APCD air pollution control device

ASME American Society of Mechanical Engineers

BACT best available control technology

BDT best demonstrated technology

BID background information document (see also 1995 BID)

CAA Clean Air Act

CAM compliance assurance monitoring

Cd cadmium

CEMS continuous emissions monitoring system(s)

CFR Code of Federal Regulations

CO carbon monoxide

COMS continuous opacity monitoring system(s)

dioxins polychlorinated dibenzo-p-dioxins

DSI dry sorbent injection 

EPA U.S. Environmental Protection Agency

ESP electrostatic precipitator

EU European Union

FBC fluidized bed combustor

FF fabric filter (baghouse)

FR Federal Register

furans polychlorinated dibenzofurans

GCP good combustion practice

HCl hydrogen chloride

Hg mercury
11

HMIWI hospital/medical/infectious waste incinerator

HWC hazardous waste combustor

MACT maximum available control technology

MB mass burn

MB/WW mass burn/waterwall combustor

MOD/EA modular/excess air combustor

MOD/SA modular/starved air combustor

MSW municipal solid waste

MWC municipal waste combustion

NOx nitrogen oxides

NSPS new source performance standards

O2 oxygen

OMB Office of Management and Budget

Pb lead

PCBs polychlorinated biphenyls

PM particulate matter

PTC power test code (see ASME)

QA quality assurance

QC quality control

RDF refuse-derived fuel

REF refractory

SD spray dryer

SD/FF/CI spray dryer/fabric filter/carbon injection

SNCR selective non-catalytic reduction 

SO2 sulfur dioxide

USC United States Code

VOC volatile organic compound
12

Abbreviations for Units of Measure

Btu = British thermal unit

°C = degrees Celsius

dscf = dry standard cubic foot (@ 14.7 psia, 68 °F)

dscm = dry standard cubic meter (@ 14 psia, 68 °F)

°F = degrees Fahrenheit

kg = kilogram (10+3 grams)

lb = pound

m3 = cubic meter

mg = milligrams (10-3 grams)

Mg = megagram (10+6 grams)

MMBtu = million Btu

ng = nanogram (10-9 grams)

ppm = parts per million

ppmv = parts per million by volume

tpd = tons per day

tons/yr = tons per year

μg = microgram (10-6 grams)

yr = year
13

3.0 COMMENTS ON NEW SOURCE PERFORMANCE STANDARDS (NSPS)

3.1 SELECTION OF SOURCE CATEGORY 

Comment: One commenter (IV-G-03) recommended that EPA include a definition of medical

waste in the NSPS. The commenter (IV-G-03) noted that medical waste is excluded from the

definition of “municipal solid waste,” but the NSPS does not include a definition of medical waste.

Response: The EPA added a reference to the Hospital/Medical/Infectious Waste Incinerators

(HMIWI) definition of medical/infectious waste to the NSPS (§60.1465).

Comment: One commenter (IV-G-03) requested that EPA clarify, as it did in the rules for

HMIWI (62 FR 48347, September 15, 1997), that emissions from crematoriums and disposal of

pathological waste, or waste from agricultural operations will be covered in a future rulemaking. 

Response: The NSPS promulgated for MWC units apply only to units combusting municipal

solid waste (MSW) and the EPA believes the applicability of the MWC rules is clear as written. Other

rules will address or have addressed combustion of waste that are not MSW, including emissions from

crematoriums and disposal of pathological waste and agricultural waste.

Comment: One commenter (IV-G-03) recommended that EPA include a definition of “clean

wood” in the rules for small MWC units. The commenter (IV-G-03) noted that the requirements that

apply to air curtain incinerators are unclear because the definition of “clean wood” has not been

included in the regulation. The commenter (IV-G-03) provided a definition consistent with the

definition of “clean wood” in the large MWC unit NSPS (40 CFR 60.51b).

Response: As proposed, §60.1465 of the NSPS for small MWC units already contains a

definition of “clean wood.” This definition is the same definition of “clean wood” that is used in the

NSPS for large MWC units and no change is necessary (see Section 3.1 of 1995 BID; the 1995 BID

is discussed on Section 2.0 of this document). 
14

3.2 SELECTION OF AFFECTED FACILITIES 

Comment: One commenter (IV-G-03) requested that EPA clarify whether NSPS would apply

to units that commenced construction between NSPS proposal (August 30, 1999), and NSPS

promulgation. The commenter (IV-G-03) noted that the proposed emission guidelines apply to units

that commenced construction before August 30, 1999 and the NSPS applies to units that commenced

construction after the final rule is published. 

Response: Section 60.1015(a)(1) of the NSPS is corrected in the final rule. The NSPS

applies to MWC units that commenced construction after August 30, 1999 or commenced

reconstruction or modification at least 6 months after the date the final rule was published.

Comment: One commenter (IV-D-06) recommended that bushes, shrubs, and clippings from

bushes and shrubs should be included in the definition of clean wood and should not be subject to the

requirements under the proposed NSPS. The commenter (IV-D-06) noted that there seems to be a

very fine distinction between clean wood and certain yard waste. In the proposed rules (§60.1465 of

Subpart AAAA and §60.1940 of Subpart BBBB), clean wood includes tree stumps (whole or

chipped), and tree limbs (whole or chipped); yard waste includes bushes, shrubs and clippings from

bushes and shrubs. The commenter (IV-D-06) believes that it would be very difficult to distinguish

between this type of yard waste (bushes, shrubs, and clippings from bushes and shrubs) and clean

wood, especially if the material is chipped. The commenter (IV-D-06) stated that the difficulty in

enforcing this regulation necessitates a change. 

Response: The proposed definitions of yard waste and clean wood waste are the same as the

NSPS promulgated for large MWC units in 1995 and reflect the comments taken on the definitions at

that time. The final NSPS for small MWC units reinstate the 1995 standards and use the same

definitions to be consistent with the NSPS for large MWC units. 

Comment: One commenter (IV-D-06) believes that it is unnecessary to develop a federal

regulation that covers air curtain incinerators. The commenter (IV-D-06) noted that in North Dakota

and in many other States, air curtain incinerators are already subject to opacity limitations when burning

yard wastes. The commenter (IV-D-06) believes that the proposed rule would only discourage use of

air curtain incinerators for burning certain types of yard waste and clean wood and may cause more

pollution by encouraging open burning. The commenter (IV-D-06) stated that air curtain incinerators
15

that are used to burn clean wood and certain yard waste provide a cleaner method of disposal than

open burning and help eliminate this material from solid waste landfills. 

Response: The EPA is required by Section 129 of the CAA to regulate emissions from air

curtain incinerators. The EPA believes it is unlikely that regulating air curtain incinerators will lead to

more open burning. 

Comment: One commenter (IV-G-03) recommended that EPA reorganize the air curtain

incinerator requirements so that the exemption from particular requirements of the NSPS are more

clear.

Response: The EPA agrees with the commenter and has reorganized the exemptions for air

curtain incinerators. The section of the final NSPS (§60.1445) applying to air curtain incinerators

reiterates the exemptions contained in §60.1020(k) of the NSPS. The EPA believes that these changes

will help clarify which exemptions and emission limits apply to air curtain incinerators.

3.3 SELECTION OF THE MAXIMUM ACHIEVABLE CONTROL TECHNOLOGY

(MACT)

3.3.1 General Comments on Emission Levels

Comment: One commenter (IV-D-25, IV-D-22) recommended that the subcategories should

be consolidated into one class of small MWC units with one set of limits for new and existing facilities. 

The commenter (IV-D-25, IV-D-22) stated that the technology currently exists to easily achieve the

most stringent of the proposed levels for all pollutants. The commenter (IV-D-25, IV-D-22) stated

that combining classes would greatly simplify the rule and place it more in line with emission limits

currently in place in other heavily industrialized countries. 

Response: Section 129 requires that separate regulations must be developed for new MWC

units and existing MWC units and specifies different criteria for determining the MACT floors for new

versus existing units. Section 129 allows different emissions limits for new versus existing sources. The

EPA believes the subcategorization and emission limits in the final regulations for new and existing

MWC units have been determined appropriately. 

3.3.2 Municipal Waste Combustor Organics

Comment: One commenter (IV-D-07) stated that the NSPS emission limit for dioxins is overly

stringent and could be set closer to the MACT floor and still provide good environmental protection.
16

Response: The limit for dioxins/furans emissions in the NSPS is set at the performance level

achieved by the best controlled similar source and includes a margin for variability in emissions. This is

required by Section 129 of the CAA (see Section 3.4 of 1995 BID).

3.3.3 Municipal Waste Combustor Metals (Mercury)

Comment: One commenter (IV-D-07) stated that the emission limit for mercury is overly

stringent and could be set closer to the MACT floor and still provide good environmental protection.

Response: The EPA analyzed of available test data, including pilot studies of carbon injection

(CI) systems and commercial applications of CI in the U.S., and has concluded the mercury emission

limits can be continuously achieved. The EPA chose CI as the basis for achieving MACT because of

its demonstrated performance and reasonable cost (see Section 3.5.4 of 1995 BID).

3.3.4 Nitrogen Oxides

Comment: One commenter (IV-D-25) stated that by not requiring Class II units to control

NOX, EPA has created a loophole that will encourage new small facilities to avoid NOX control by

limiting plant capacity to 250 tons per day or less. The commenter (IV-D-25) stated that not requiring

NOX control for Class II units could significantly increase facility NOX emissions. In addition, the

commenter (IV-D-25) stated that, based on current technology, all units, regardless of size or design,

should be required to control oxides of nitrogen. The commenter (IV-D-25) stated that, at a minimum,

NOX limits should be established at a level based on the equivalent of a 50 percent reduction for all

MWC units. The commenter (IV-D-25) asserted that this level of control is easily achievable with

currently available technology and is being demonstrated on small MWC units in Europe and Japan as

well as on many types of small combustion processes in the U.S.

Response: The EPA has added a “no control” NOx emission limit of 500 ppmv for all new

Class II units. The 500 ppmv emission limit is consistent with the NSPS as proposed on

September 20, 1994 (59 FR 48225). This final limit is not intended to result in NOx emissions control,

and the final NSPS does not include any monitoring, testing, recordkeeping, or reporting requirements

associated with the final NOx limit for Class II units. As analyzed in 1995 (59 FR 48225), EPA

continues to conclude NOx emission control is not appropriate to Class II MWC units and control is

not required. 
17

Comment: One commenter (IV-D-20) requested that the requirement for nitrogen oxides

control of Class I small MWC units for the NSPS be eliminated for refractory lined combustion

chambers. The commenter (IV-D-20) believes that all of the MACT facilities used to establish the

emissions limits for Class I are based upon waterwall furnace designs. The commenter’s (IV-D-20)

design does not employ a waterwall furnace and is based upon refractory lined combustion chambers

with horizontal heat recovery steam generators. The commenter (IV-D-20) stated that refractorybased designs in Class I with post combustion recovery in waste heat type steam generation equipment

do not provide an optimal temperature range for selective non-catalytic reduction (SNCR) employment

with sufficient time for reaction to occur.

Response: The EPA is limiting NOx emissions from all new Class I small MWC units to the

same level to assure new MWC units are environmentally competitive. The NSPS applies to future

MWC units; therefore, operators can select an MWC type that can most easily comply with the

emission standards. Section 111 of the CAA allows the EPA to set a high performance standard for

new units, encouraging the use of lower-emitting or more easily controlled technology.

3.3.5 Good Combustion Practices

Comment: One commenter (IV-F-1g) requested that EPA clarify that a 12-hour shift is typical

for operators versus the 8-hour shift that seems to be referenced in the control room operator stand-in

provision in §60.1195. 

Response: The EPA agrees with the commenter that a 12-hour shift is more typical for MWC

operators. The EPA revised §60.1195(a) and (b) of Subpart AAAA and §60.1685(a) and (b) of

Subpart BBBB to reflect a 12-hour shift, rather than an 8-hour shift. The EPA revised the

recordkeeping requirements in §60.1410(l) of Subpart AAAA and §60.1885(l) of Subpart BBBB so

that they apply when all chief facility operators and certified shift supervisors are offsite for more than

12 hours. In addition, EPA revised the regulation to clarify the boundary limits in §60.1685 of

Subpart BBBB and §60.1195 of Subpart AAAA as "12 hours or less" and "2 weeks or less". 

Comment: Two commenters (IV-D-27, IV-G-02) suggested that EPA revise the NSPS and

footnote b of Table 5 of Subpart BBBB to be consistent with the long term CO analysis memorandum

in Docket No. A-98-18. The proposed footnote b to table 5 states that all averages are block

averages, however, according to the memorandum in the docket (item II-B-8), EPA established the
18

200 ppm limit as a 24-hour geometric mean average concentration (rather than an arithmetic average). 

One commenter (IV-G-02) requested that EPA add a footnote to the NSPS (Table 2 of Subpart

AAAA) that applies to “Fluidized bed, mixed fuel, (wood/refuse-derived fuel)” and “Mass burn rotary

waterwall,” and reads: “c. 24-hour daily block geometric average concentration.”

Response: The EPA revised Table 2 of Subpart AAAA to add the combustor type, fluidized

bed, mixed fuel (wood/refuse-derived fuel), with a CO emission limit of 200 ppm and a 24-hour

geometric mean averaging time. This revision is consistent with the CO analysis memo in Docket

No. A-98-18. The averaging time and method for mass burn rotary waterwall is correct as published

and is consistent with the final 1995 NSPS, which are being reinstated.

3.3.6 Size Categories of New Municipal Waste Combustor Units

Comment: One commenter (IV-D-25, IV-D-22) stated that there is no health or technological

basis for EPA’s decision to subcategorize the new MWC units based on overall facility size. The

commenter (IV-D-25, IV-D-22) recommended that EPA reconsider the proposed subcategories and

emission limits based on actual operating data. The commenter (IV-D-25, IV-D-22) provided data to

support its recommendation. The commenter (IV-D-25, IV-D-22) stated that the technology currently

exists for all sizes of small MWC units to easily achieve the most stringent of the proposed levels for all

pollutants. 

Response: The EPA agrees that the subcategorization could be done in different ways. 

However, in the 1995 NSPS (40 CFR part 60, Subpart Eb), the EPA elected to use an aggregate

plant capacity of 250 tons per day to subcategorize small MWC units. The EPA believes that

approach is a valid way to subcategorize, and notes that Section 129 allows such subcategorization. In

the litigation of the 1995 MWC rule, the court indicated subcategorization by unit location was a valid

approach. Because the purpose of this rulemaking is to reestablish the 1995 NSPS for new small

MWC units with combustion capacities of 35 to 250 tons per day of MSW, EPA is retaining the

subcategorization used in the 1995 NSPS. 
19

3.4 PERFORMANCE TEST METHODS AND MONITORING 

3.4.1 Continuous Monitoring

Comment: Four commenters (IV-G-01, IV-G-02, IV-G-07, IV-F-1f) requested that EPA

consider removing or revising the SO2 monitoring requirements for all small MWC facilities because the

costs for SO2 CEMS are not reasonable relative to the amount of SO2 emitted from small MWC units. 

Two commenters (IV-G-01, IV-G-07) claimed that municipal solid waste is a low sulfur fuel and

removing the SO2 monitoring would be consistent with EPA policy for other low-sulfur fuels. One

commenter (IV-G-02) requested that EPA allow Class C facilities to use a work-practice monitoring

requirement similar to that for activated carbon, but applied to acid gas control reagent utilization, in

place of a requirement to use an SO2 CEM. A fourth commenter (IV-F-1f) stated that the CEMS

QA/QC and recordkeeping and reporting requirements for both SO2 and CO are onerous for Class C

facilities relative to the CO and SO2 emissions from these facilities.

Response: The EPA believes that the SO2 and CO monitoring contained in the proposed rule

is reasonable for known applications and the final rules retain those requirements. However, the

general provisions to part 60 (40 CFR part 60, Subpart A) allow the Administrator to approve

alternative or equivalent monitoring proposals, such as parameter monitoring for a control device, on a

case-by-case basis. 

Comment: One commenter (IV-D-07) recommended that EPA allow for measuring unit load

using alternative technologies that exhibit equivalent accuracy. The commenter (IV-D-07) believes that

load level control through steam flow measurement is appropriate, but the ASME Power Test Code

referenced in the proposal is specific to only one method of flow measurement: an orifice or nozzle used

in conjunction with a differential pressure measuring device. The commenter (IV-D-07) noted that

ASME PTCs do not address other technologies for flow measurement. The commenter (IV-D-07)

requested that flexibility be provided for those MWC units that use other methods of measurement

(e.g., annubar, vortex shedder, mag meters). 

Response: The general provisions to part 60 (40 CFR part 60, Subpart A) allow the

Administrator to approve alternative or equivalent monitoring proposals on a case-by-case basis. The

owner or operator may apply for a site-specific alternative monitoring requirement.

Comment: One commenter (IV-D-07) recommended that the requirement for visual opacity

determination be waived if a properly certified and maintained continuous opacity monitoring system
20

(COMS) is in service. The commenter (IV-D-07) stated that EPA Reference Method 9 is a poor

substitute for a calibrated COMS. The commenter (IV-D-07) believes the requirement to measure

opacity by both performance testing using Method 9 as well as COMS will result in additional testing

expense without any corresponding benefit.

Response: Opacity measurement by EPA Reference Method 9 is the means for enforcement of

the opacity standards. However, the general provisions to part 60 (40 CFR part 60, Subpart A) allow

the Administrator to approve alternative test methods or waive testing on a case-by-case basis. 

Comment: One commenter (IV-D-20) claimed that at their MWC plant, two MWC units

discharge flue gases to the same heat recovery steam generator (boiler) and the plant is unable to

comply with the requirement for steam flow monitoring on an individual MWC unit basis as required in

§60.1320 of Subpart AAAA because of the use of common heat recovery equipment. For this plant,

the steam flow is indicative of total facility steam flow rather than individual combustion unit steam flow. 

In addition, the commenter (IV-D-20) stated that another MWC plant is unable to comply with the

requirement for continuous monitoring of the regulated emission parameters, on a per unit basis, as

required in §§60.1225 and 60.1230 of Subpart AAAA and §§60.1715 and 60.1720 of Subpart

BBBB or routine performance testing of regulated emission parameters, due to the lack of separate

heat recovery equipment for each combustion unit. The commenter (IV-D-20) requested that the

requirements for individual steam flow monitoring, continuous emissions monitoring and performance

testing on individual combustion units be revised to include provisions for common steam generation

and air pollution control systems with multiple combustion units. The commenter (IV-D-20) requested

that these proposed revisions be made for both existing and new waste combustion facilities. The

revisions are necessary for new facilities because the commenter (IV-D-20) has developed new facility

designs that employ common steam generation equipment with multiple combustion units to aid in

dampening fluctuations in heat release. According to the commenter (IV-D-20), common air pollution

control equipment is usually used when common heat recovery equipment is used. 

Response: The general provisions to part 60 (40 CFR part 60, Subpart A) allow the

Administrator to approve alternative or equivalent monitoring proposals on a case-by-case basis. 
21

3.4.2 Test Methods

Comment: Several commenters (IV-D-14, IV-D-05, IV-D-09, IV-G-06, IV-F-1g) requested

that EPA clarify the accuracy of the EPA test methods used to demonstrate compliance with the

emission limits. Some commenters (IV-D-14, IV-D-09, IV-F-1g) were concerned that uncertainty in

the test methods could lead to a higher risk of noncompliance for facilities, especially if States adopt

more stringent standards than the NSPS. Another commenter (IV-D-09) suggested that uncertainty in

the test methods could lead to a lack of enforcement of the standards.

Response: The test methods are adequate to use in application of the MWC regulations. The

development of the test methods is not part of this rulemaking. The adequacy of the test methods was

addressed in establishment of the test methods and was done as a separate rulemaking. The EPA

proposed and accepted comments on the test methods in that rulemaking. Questions submitted about

the accuracy of the test methods have been forwarded to the EPA emission measurement laboratory

for evaluation outside this rulemaking (see Section 3.8.3 of 1995 BID).

Comment: Three commenters (IV-G-06, IV-D-01, IV-F-1f) stated that the standards must

better address uncertainty in the emission measurement methods. One commenter (IV-G-06)

suggested a way to revise the equations in §60.1460 of the NSPS and §60.1935 of the emission

guidelines for determining percent reductions for Hg and HCl to better account for measurement

uncertainty. Two commenters (IV-D-01, IV-F-1f) also stated that the test methods for Pb, Cd, Hg

and dioxins/furans emissions have too much uncertainty and cannot be used for determining compliance

with the emission limits. One commenter (IV-F-1f) also stated that EPA must account for both process

variability and measurement uncertainty in setting emission limits. Finally, two commenters

(IV-D-01, IV-F-1f) stated that Section 129(c) of the CAA requires that emission standards must be

based on test methods validated on solid waste combustion units.

Response: The EPA believes that all methods specified in the NSPS are valid for use on

MWC units. The docket contains several reports that identify method validation studies conducted on

these methods on MWC units and similar sources. In addition, the emissions data on which the

standards are based are the same measurement methods that will be used to determine compliance. 

Process variations and emission variations result in emission data variation and all emission

measurement methods have some uncertainty. The proposed emission limits account for all of these

factors (process variation, emission variation, and measurement uncertainty). Additionally, these test
22

methods and calculation procedures are the same as those included in the 1995 standards (see

Section 3.8.3 of 1995 BID).

Comment: Two commenters (IV-G-06, IV-F-1f) noted that the likelihood of a violation

increases as the number of limits in the standard increases and as the number of units at a plant

increases. The commenters were concerned that the emission limits are based on individual

achievement of the limits and not simultaneous achievement of all the limits. The commenters suggested

that the language of §60.1215 of the NSPS be revised so that small exceedances of the limits are not

considered violations if subsequent testing indicates compliance or if the exceedance is within the

measurement uncertainty of the test methods. One commenter (IV-F-1f) also asked EPA to solicit

comments on determining measurement uncertainty using EPA Method 301 and at the proposed

regulatory limits, and on demonstrating compliance with multiple limits that were set based on data from

individual emission tests.

Response: The proposed limits include a consideration for measurement uncertainty and

process variability and are simultaneously achievable. Allowances for small exceedances, as suggested

by the commenters, are not needed. The EPA has already accepted comments on the test methods

and the achievability of the emission limits. The EPA sees no need to solicit additional comments.

Comment: One commenter (IV-D-07) asked EPA to clarify the compliance testing schedule. 

The commenter (IV-D-07) stated that §60.1795(b) appears to require dioxin testing on an annual basis

whereas §60.1795(a) states that stack testing can occur each 36 months if all stack tests for a given

pollutant show emission levels that are less than the limit for the unit in question. The commenter

(IV-D-07) supports stack testing at a reasonable frequency and considers annual stack testing, without

some relief provision recognizing proper operation or superior performance, is unreasonable. The

commenter (IV-D-07) supports the proposed frequency for stack testing if §60.1795(a) applies to all

of the tests required under §60.1785, including dioxins/furans testing.

Response: All Class I and II units must do stack tests for dioxins/furans annually (§60.1285);

however, the regulation does allow for reduced testing for Class I and II units (§60.1305). For Class I,

reduced testing of dioxins/furans is allowed for MWC units that have demonstrated levels of

dioxins/furans less than or equal to 7 nanograms per dry standard cubic meter for 2 consecutive years

(§60.1305 (b)) . For Class II units, two reduced testing options are available. (1) Similar to the

reduced testing described above, reduced testing of dioxins/furans is allowed for MWC units that have
23

demonstrated levels of dioxins/furans less than or equal to 7 nanograms per dry standard cubic meter

for 2 consecutive years. (2) Reduced testing of all pollutants is allowed for Class II MWC units that

have demonstrated compliance with all pollutants, including dioxins/furans, over 3 consecutive years

(§60.1305(b)). These sections of the NSPS have been edited to make these provisions more clear. 

Comment: One commenter (IV-F-1f) stated that the annual retest language (§60.1295 of

NSPS) should be changed to require annual retesting, either within 13 months or within 54 weeks. The

commenter (IV-F-1f) pointed out that the current retest language can create a rollback or ratchet

effect, where you actually have less than twelve months to retest. The commenter (IV-F-1f) stated that

the language could be interpreted as meaning within 12 months from the day the last test was finished,

not 12 months from the month it was finished.

Response: The EPA agrees with the commenter that the current requirement to test within 12

months of the last test could imply that annual stack tests must be no later than 12 months apart. 

Because it may be difficult to schedule tests exactly 12 months apart, the testing schedule would be

compressed so it was more frequent than annual testing. The NSPS has been revised to require annual

stack tests to be no later than 13 months apart to allow some flexibility in the annual scheduling tests.

Comment: Three commenters (IV-G-01, IV-G-07, IV-F-1f) support maintaining a 3-hour

minimum sampling time for dioxin and furan test runs. The commenters (IV-G-01, IV-G-07) believe a

4-hour minimum sampling time will not add significantly to the accuracy of the test results and will add

extra costs for testing and impose an additional burden on the stack test team. The commenters

(IV-G-01, IV-G-07) stated that the extra sampling hours easily add an additional day to a

dioxins/furans stack test. One commenter (IV-G-01) noted that 3 runs of 4 hours each takes well over

12 hours to complete without errors. The other commenter (IV-G-07) stated that adding an additional

day to a dioxins/furans stack test could skew the test results and create another potential for error to the

test.

Response: The EPA is keeping the requirement for a 4-hour sampling time for the

dioxins/furans test method in the NSPS. However, facility operators have the option of applying to the

Administrator for approval to use a shorter sampling time on a case-by-case basis, under the general

provisions (40 CFR part 60, Subpart A). The test method sections of the NSPS has been revised to

clarify that facility operators may apply to the Administrator for approval of alternative or equivalent test

methods or modifications of the final test methods.
24

Comment: One commenter (IV-G-06) recommended modifying §60.1935(a) of the MWC

rule to eliminate the problem of public misperception of adverse environmental consequences

associated with inappropriately inflated emitted concentrations during startup and shutdown due to the

mathematical effects of the oxygen correction factor. The commenter (IV-G-06) acknowledges the

EPA’s recognition in the hazardous waste combustor (HWC) proposal that the concentration

correction to 7 percent oxygen becomes very large and essentially meaningless during start-up and

shutdown. However, the commenter (IV-G-06) disagrees with the approach in the HWC MACT

standard that requires the facility to identify (in their startup, shutdown, malfunction plan) an oxygen

correction factor to use during periods of start up and shut down. 

Response: The commenter refers to sections of the emission guidelines, however, there are

parallel provisions in the NSPS. The EPA sees no need to modify the oxygen correction factor for

startup and shutdown periods. The NSPS do not regulate emissions during these periods and do not

require recording or reporting emissions during these events. 

Comment: One commenter (IV-F-1f) presented an alternative dry sorbent injection test

procedure that uses Method 19 to determine removal efficiency along with CEMS. The commenter

(IV-F-1f) stated that the proposed rule has some undefined terms that are defined in Method 19. The

commenter (IV-F-1f) presented a test procedure that gives two baselines and a control, which allows

you to determine control efficiency as one measures the concentration when the sorbent is injected

versus when it is not injected, and make an uncertainty correction based on the dual train results. The

commenter (IV-F-1f) stated that the unit should be considered in compliance if both data sets meet the

standard.

Response: The EPA is not modifying the current test procedures for determining removal

efficiency for HCl and SO2. However, owners and operators have the option of applying to the

Administrator for approval to use alternative test methods on a case-by-case basis, under the general

provisions (40 CFR part 60, Subpart A). 

Comment: One commenter (IV-F-1f) stated that they have not found a way of flue gas

sampling at the point before their dry sorbent injection system. The commenter (IV-F-1f) stated that

the injection location is at the bottom of a u-bend and the temperature is too high (650°F) to keep any

extractive or in situ system working. Therefore, they must determine the uncontrolled state by turning

off the dry sorbent injection system. The commenter (IV-F-1f) stated that in order to get accurate
25

measurements of uncontrolled emissions, the dry sorbent injection system needs to be turned off for at

least 12 hours prior to the test. The commenter (IV-F-1f) stated that the HWC MACT rule stipulates

that work practice limits are waived during testing. The commenter (IV-F-1f) requested that a similar

requirement be added to this rule. The commenter (IV-F-1f) stated that this would avoid the situation

where a State will not allow the pollution control equipment to be turned off to determine if the

efficiency limits are being met. 

Response: Facility owners can comply with either the HCl and SO2 reduction requirements or

the HCl and SO2 concentration limits. If they must turn off the acid gas control system (e.g., the dry

sorbent injection system) to measure HCl or SO2 removal efficiency, the operator can complete testing

before the compliance date for their facility without violating the emission standards. After the

compliance date, facility operators can use a parametric method for determining removal efficiency. In

addition, the docket for the large MWC rulemaking contains a paper (Docket A-89-08, IV-B-22)

describing this procedure. Facility operators already have the option of applying to the Administrator

for approval to use parametric monitoring or alternative test methods on a case-by-case basis, under

the general provisions (40 CFR part 60, Subpart A). 

3.5 STARTUP, SHUTDOWN, AND MALFUNCTION

Comment: One commenter (IV-D-13) stated that there is no rationale for limiting the startup,

shutdown, and malfunction period to 3 hours. The commenter (IV-D-13) requested that EPA clarify

what is meant in §60.1710(b). The commenter (IV-D-13) questioned whether the section means that

the unit can never shut down for over 3 hours, or whether the shutdown process cannot last longer than

3 hours. Another commenter (IV-D-18) believes that the startup period should be expanded to 8

hours (or to at least 5 hours) to reflect actual startup times. Another commenter (IV-D-10) suggested

that EPA change the startup time to 4 hours because 3 hours may not always be enough time. The

commenter (IV-D-10) noted that most small MWC units do not have auxiliary burners for quick

startup. The commenter (IV-D-10) noted that startup of a MWC unit after installation of refractory

and stoker failure are just two events when a startup or shutdown could go beyond 3 hours. 

Response: The commenter refers to sections of the emission guidelines, however, there are

parallel provisions in the NSPS. The regulatory text has been edited to make the intent of §60.1710

clear. A maximum of 3 hours of test data can be dismissed from calculations during periods of startup,
26

shutdown or malfunction. For startup, shutdown or malfunction periods longer than 3 hours, emissions

data cannot be discarded from calculations and all provisions under §60.11(d) to minimize emissions

are in full force. The EPA believes that the 3-hour period included in the proposal is appropriate for

startup, shutdown, or malfunction and it is maintained in the final regulations. The 3-hour period does

not begin until waste is fed to the grate and stops when waste is no longer fed to the grate. 

3.6 LEGAL CONSIDERATIONS 

Comment: One commenter (IV-D-23) stated that EPA’s failure to include standards for

MWC units with capacities of less than 35 megagrams per day would be unlawful. The commenter

(IV-D-23) cited the CAA, which requires EPA to promulgate emission standards for all units

combusting municipal waste (42 U.S.C. 7429(a)(1)). The commenter (IV-D-23) stated that there is

no basis for EPA’s decision not to include standards for units with capacities of less than 35 Mg per

day (64 FR 47236) in this rulemaking. The commenter (IV-D-23) states that, accordingly, the

regulations for small MWC will violate the CAA if they do not include standards for such units. 

Response: The EPA is reestablishing the 1995 regulations for small MWC units. Those

regulations included a lower size cutoff. This does not mean that EPA will not develop regulations for

units smaller than 35 tons per day. The EPA considers MWC units smaller than 35 tons per day to be

a separate subcategory of small MWC units. Section 129(a)(2) of the CAA specifically authorizes

EPA to distinguish among sizes of units within a category in establishing standards. The EPA is not

addressing requirements for MWC units smaller than 35 tons per day in this rulemaking.

Comment: One commenter (IV-D-23) stated that EPA’s failure to establish numerical emission

limits for NOX for Class II MWC units violates the CAA. The commenter (IV-D-23) cited

Section 129(a)(4) of the CAA that says performance standards applicable to solid waste incineration

units “shall specify numerical emission limitations for the following substances or mixtures: particulate

matter (total and fine), opacity (as appropriate), sulfur dioxide, hydrogen chloride, oxides of nitrogen,

carbon monoxide, lead, cadmium, mercury, and dioxins and dibenzofurans.” Because the proposed

rule does not specify numerical emission limitations for oxides of nitrogen for Class II units, it would

violate the CAA. The commenter (IV-D-23) noted that EPA did not explain why the proposed

standards do not specify numerical emission limitations for NOX, but merely cited the preamble to the

1995 regulations (59 FR 48228). The commenter (IV-D-23) stated that EPA’s failure to comply with
27

the CAA in promulgating standards for large MWC units does not excuse its failure to comply with the

CAA in promulgating standards for small MWC units. The commenter (IV-D-23) stated that the CAA

requires the EPA to promulgate these standards and no EPA explanation can alter this requirement. 

Response: The commenter correctly points out that Section 129 of the CAA requires NOX

limits. This means that emission limits for these pollutants must be specified even if the best controlled

similar source (MACT performance level) does not control NOX. None of the Class II units has NOX

controls and MACT does not require NOX control. However, in the final rule, EPA has added a “no

control” NOX emission limit of 500 ppmv for all new Class II units. The 500 ppmv emission limit is

consistent with the "no control" NOX limit as proposed for the NSPS on September 20, 1994 (59 FR

48225).

This final limit is not intended to result in NOX emissions control, and the final NSPS for

Class II MWC units does not include any associated NOX monitoring, testing, recordkeeping, or

reporting requirements. The 500 ppmv limit represents an emission level with adequate margin to

accommodate the variability in NOX emission levels from an uncontrolled MWC unit. Test data in the

docket indicate that this level is achievable for all combustor types. 

Comment: One commenter (IV-D-23) stated that the omission of CO limits (and an

explanation) constitute a violation of the CAA. The commenter (IV-D-23) noted that the proposed

rule does not specify numerical emission standards for CO, except for a limited subcategory of fluidized

bed combustion units the co-fire wood and RDF. The commenter stated that the failure to specify

numerical CO emission limits constitutes a missed opportunity to reduce dioxins/furans emissions since

CO levels are indicative of good combustion and good combustion reduces dioxins/furans levels. 

Response: The commenter is mistaken and has missed part of the regulations. Table 2 of

Subpart AAAA (64 FR 47304) and Table 5 of Subpart BBBB (64 FR 47271) list the proposed CO

emission limits for new and existing small MWC units, respectively. All small MWC units are subject to

CO limits in the proposed and final regulations. The CO limits are listed in Table 2 of Subpart AAAA.

Comment: One commenter (IV-D-23) stated that EPA’s failure to establish numerical emission

limits for polychlorinated biphenyls (PCBs) violates the CAA. The commenter (IV-D-23) cited

Section 112(c)(6) of the CAA, which requires EPA to assure that source categories accounting for

90 percent of all PCB emissions are subject to MACT standards “with respect to” PCBs. The

commenter (IV-D-23) cited EPA as stating that MWC units account for more than half of the
28

aggregate emissions of PCBs (63 FR 17838 and 17849, April 10, 1998). The commenter (IV-D-23)

argues that EPA cannot possibly meet the requirements of Section 112(c)(6) without subjecting MWC

units, including the small MWC subcategory, to MACT standards for PCBs. The commenter also

pointed out that EPA has acknowledged in its final Great Waters determination under

Section 112(m)(6) of the CAA, that “Section 112(c)(6) requires that EPA identify and list for

regulation sources to assure that at least 90 percent of the aggregate emissions of each of seven

pollutants are subject to Section 112(d) standards” (63 FR 14090, March 24, 1998). The commenter

(IV-D-23) stated that therefore, the small MWC regulations will violate the CAA if they do not include

PCB standards.

Response: The commenter cited Section 112(c)(6) of the CAA. However, the small MWC

regulations were developed under Section 129 of the CAA. Section 129 does not require regulation of

PCB from small MWC. The EPA does not believe that Congress intended that the solid waste

incineration units required to be regulated under section 129 of the CAA be subject to section

112(c)(6) of the CAA. Section 129(a)(4) of the CAA requires EPA to establish numerical emission

limitations for a specified list of pollutants. Had Congress intended to require that PCB emissions from

solid waste incineration units be specifically controlled, EPA believes Congress would have included

PCB in the list of pollutants for which numerical emission limitations are required. Congress did not do

so. The control technologies used to comply with the small MWC regulations will, nevertheless, result

in reductions in PCB. Adding specific emission limits for PCB is not required and would not result in

further reduction in PCB emissions from small MWC. PCB emission limits are, therefore, not included

in the final regulations.

Comment: One commenter (IV-D-23) stated that EPA’s failure to establish final emission

standards that reflect the reductions achievable through pollution prevention measures violates the

CAA. The commenter (IV-D-23) cited Section 129(a)(2) and (a)(3) of the CAA and believes that

these requirements must be read together and that if any measure, including a pre-combustion measure,

is necessary to obtain the maximum reduction that is achievable, EPA must require it. The commenter

(IV-D-23) believes that failing to evaluate the effectiveness and achievability of measures identified by

EPA or advocated by commenters is arbitrary and capricious (AT&T corp. V. FCC, 86 F.2d 242,

247 (D.C. Cir. 1996)).
29

The commenter (IV-D-23) advocates eliminating or reducing metals and chlorinated plastics in

the waste stream at small MWC facilities. The commenter (IV-D-23) believes that this is an achievable

beyond-the-floor measure that would reduce metals emissions beyond the floor requirements, and

reduction of chlorinated plastics would reduce dioxin and hydrogen chloride emissions. The commenter

(IV-D-23) states that it is feasible both technically and economically for MWC owners or operators to

separate metals or require their customers to do so. The commenter (IV-D-23) states that feed limits

are particularly appropriate for mercury, lead, and cadmium, which are known to be significant adverse

“non-air quality health and environmental impacts.” Another commenter (IV-D-07) recommended that

EPA take a lead role in pollution prevention through product formulation controls, which is an initiative

that is fundamental to the protection of our soil, air, and water. The commenter (IV-D-07) believes

that it would be most prudent to control toxic metals at the source where control is highly efficient and

cost effective. The commenter (IV-D-07) stated that there has been no comprehensive national effort

to control toxic metals at the true source, the mines and markets that produce and distribute them.

Response: Commenter IV-D-23 raised the same issue in its litigation of the regulations for

Hospital/Medical/Infectious Waste Incinerators (HMIWI). In the Sierra Club decision (Sierra Club v.

EPA, 167 F.3d 658, 663 (D.C. Cir. 1999)) for the HMIWI rule, the court rejected the commenter’s

claim. In that litigation, the court said that “[i]n the absence of any type of quantification of benefits or

costs, the Administrator had no basis for finding that, ‘taking into account the cost,’ emissions

reductions from pollution prevention programs were ‘achievable’ as the statute uses the word.” As in

the HMIWI rule, EPA does not have evidence that allows quantification of the relevant reduction

achievable through pollution prevention measures (e.g., including control of consumer products). 

However, EPA has included the following pollution prevention measures in the regulations. New small

MWC units subject to the NSPS must prepare a materials separation plan, which identifies a goal and

an approach for separating certain components of municipal solid waste prior to combustion and

making them available for recycling. In addition, new and existing small MWC units must maintain a

specified load level and maintain a specified temperature at the inlet of the PM control device. These

operating requirements help assure good combustion, which prevents pollution (see Section 4.2 of

1995 BID).

Comment: One commenter (IV-D-23) stated that EPA’s failure to consider non-air quality

health and environmental impacts in setting final emission standards would violate the CAA. The
30

commenter (IV-D-23) cited Section 129(a)(2) of the CAA, which requires EPA to set standards that

“reflect the maximum degree of reduction in emissions of air pollutants... that the Administrator, taking

into consideration the cost of achieving such emission reduction, and any non-air quality health and

environmental impacts and energy requirements, determines is achievable...” The commenter

(IV-D-23) stated that although EPA stated that it considered non-air quality health and environmental

impacts in setting final emission standards (64 FR 47237), there is no evidence that it did so for the

proposed Class A and Class B small MWC units. The commenter (IV-D-23) believes that, for both

Class A and B MWC units, EPA neither discussed nor considered non-air quality health and

environmental impacts in deciding whether to establish more stringent emission standards.

Response: Commenter IV-D-23 raised the same issue in its litigation of the regulations for

Hospital/Medical/Infectious Waste Incinerators (HMIWI). In the Sierra Club decision (Sierra Club v.

EPA, 167 F.3d 658, 663 (D.C. Cir. 1999)) for the HMIWI rule, the court rejected the commenter’s

claim, finding that they had failed to demonstrate that the factors they present are “non-air quality health

and environmental impacts” within the meaning of Section 129. The commenter has provided no

additional information in support of their claim. EPA has fully considered what it deems to be the

potential non-air quality health and environmental impacts resulting from implementation of the

regulations. For example, EPA evaluated the increase in solid waste and wastewater resulting from

implementation of the regulations. 

Comment: One commenter (IV-D-23) stated that EPA’s failure to comply with the MACT

floor requirements of Section 129 of the CAA would violate the CAA. The commenter (IV-D-23)

cited Section 129 of the CAA, which states “the degree of reduction in emissions that is deemed

achievable for new units in a category shall not be less stringent than the emissions control that is

achieved in practice by the best controlled similar unit, as determined by the Administrator.” The

commenter (IV-D-23) stated that EPA must first identify the best controlled similar unit for each

pollutant and then must determine the emissions control that unit has achieved. The commenter

(IV-D-23) believes that EPA did not comply with this approach, but instead EPA stated that

technologies represent the MACT floor. The commenter (IV-D-23) stated that EPA may not use

technologies as the basis for MACT floors without a demonstration that the performance of these

technologies accurately reflects the actual performance of the best controlled similar unit (Sierra Club v.

EPA, 167 F.3d 658, 665 (D.C. cir. 1999)) (Sierra Club). The commenter (IV-D-23) stated that even
31

if EPA could use the performance of technologies as the basis of the MACT floors, it did not do so in a

permissible way. 

Response: The court stated in its Sierra Club HMIWI decision, “...EPA would be justified in

setting the floors at a level that is a reasonable estimate of the performance of the ‘best controlled

similar unit’ under the worst reasonably foreseeable circumstances.” The court also (correctly)

speculated that “[p]erhaps considering all units with the same technology is justifiable because the best

way to predict the worst reasonably foreseeable performance of the best unit with the available data is

to look at other units’ performance.” This is precisely why EPA used the “best technology” approach

to determine the MACT floors for new units. 

Because MACT must be achievable and there is inherent variation in emissions over time and

among MWC units, even when the MWC units and control devices are well designed, operated, and

maintained, the floor emission levels are set at levels that are demonstrated to be achievable by the

population of MWC units with the best technology (see Sections 3.4.1 and 3.11 of the 1995 BID).
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4.0 COMMENTS ON THE EMISSION GUIDELINES

4.1 SELECTION OF SOURCE CATEGORY 

Comment: One commenter (IV-G-03) recommended that EPA include a definition of medical

waste in the emission guidelines. The commenter (IV-G-03) noted that medical waste is excluded from

the definition of “municipal solid waste,” but the emission guidelines does not include a definition of

medical waste.

Response: The EPA added a reference to the HMIWI definition of medical/infectious waste to

the emission guidelines (§60.1940). 

Comment: One commenter (IV-G-03) requested that EPA clarify, as it did in the rules for

HMIWI (62 FR 48347, September 15, 1997), that emissions from crematoriums and disposal of

pathological waste, or waste from agricultural operations will be covered in a future rulemaking. 

Response: The emission guidelines apply only to units combusting municipal solid waste

(MSW) and the EPA believes the applicability of the MWC rules is clear as written. Other rules will

address the combustion of other wastes and no other clarification is needed in this rulemaking. 

Comment: One commenter (IV-G-03) recommended that EPA include a definition of “clean

wood” in the rules for small MWC units. The commenter (IV-G-03) noted that the requirements that

apply to air curtain incinerators are unclear because the definition of “clean wood” has not been

included in the regulation. The commenter (IV-G-03) provided a definition consistent with the

definition of “clean wood” in the large MWC unit NSPS (40 CFR 60.51b).

Response: Section 60.1940 of the emission guidelines already contains a definition of “clean

wood.” This definition is the same definition of “clean wood” that is used in the emission guidelines for

large MWC units and no change is necessary (see Section 3.1 of 1995 BID). 
34

4.2 SELECTION OF DESIGNATED FACILITIES

Comment: One commenter (IV-G-03) requested that EPA clarify whether the emission

guidelines apply to units that commenced construction after August 30, 1999, but before the final rule is

published. The commenter (IV-G-03) noted that the proposed emission guidelines apply to units that

commenced construction before August 30, 1999 and the NSPS applies to units that commenced

construction after the final rule is published. 

Response: No change is necessary for the emission guidelines; however, §60.1015(a)(1) of the

NSPS has been corrected in the final rule. The NSPS applies to MWC units that commenced

construction after August 30, 1999 or commenced reconstruction or modification at least 6 months

after the date the final rule is published. The emission guidelines apply to small MWC units that

commenced construction on or before August 30, 1999.

Comment: One commenter (IV-D-06) recommended that bushes, shrubs, and clippings from

bushes and shrubs should be included in the definition of clean wood and should not be subject to the

requirements under the proposed NSPS or emission guidelines. The commenter (IV-D-06) noted that

there seems to be a very fine distinction between clean wood and certain yard waste. In the proposed

rules (§60.1465 of Subpart AAAA and §60.1940 of Subpart BBBB), clean wood includes tree

stumps (whole or chipped), and tree limbs (whole or chipped); yard waste includes bushes, shrubs and

clippings from bushes and shrubs. The commenter (IV-D-06) believes that it would be very difficult to

distinguish between this type of yard waste (bushes, shrubs, and clippings from bushes and shrubs) and

clean wood, especially if the material is chipped. The commenter (IV-D-06) stated that the difficulty in

enforcing this regulation necessitates a change. 

Response: The proposed definitions of yard waste and clean wood waste are the same as the

emission guidelines promulgated for large MWC units in 1995 and reflect the comments taken on those

definitions at that time. The final emission guidelines for small MWC units reinstate the 1995 standards

and use the same definitions to be consistent with the 1995 emission guidelines for large MWC units. 

Comment: One commenter (IV-D-06) believes that it is unnecessary to develop a federal

regulation that covers air curtain incinerators. The commenter (IV-D-06) noted that in North Dakota

and in many other States, air curtain incinerators are already subject to opacity limitations when burning

yard wastes. The commenter (IV-D-06) believes that the proposed rule would only discourage use of

air curtain incinerators for burning certain types of yard waste and clean wood and may cause more
35

pollution by encouraging open burning. The commenter (IV-D-06) stated that air curtain incinerators

that are used to burn clean wood and certain yard waste provide a cleaner method of disposal than

open burning and help eliminate this material from solid waste landfills. 

Response: The EPA is required by Section 129 of the CAA to regulate emissions from air

curtain incinerators. The EPA believes it is unlikely that regulating air curtain incinerators will lead to

more open burning. 

Comment: One commenter (IV-G-03) recommended that EPA reorganize the air curtain

incinerator requirements so that the exemption from particular requirements of the MWC emission

guidelines are more clear. 

Response: The EPA agrees with the commenter and has reorganized the exemptions for air

curtain incinerators. The sections of the final emission guidelines (§60.1920) applying to air curtain

incinerators reiterate the exemptions contained in §60.1555(k) of the emission guidelines. The EPA

believes that these changes will help clarify which exemptions and emission limits apply to air curtain

incinerators.

Comment: One commenter (IV-D-08) requested clarification of the applicability of the

emission guidelines (§60.1550). The commenter (IV-D-08) noted that sections I and II of the

preamble describe the emission guidelines defining small MWC units as having capacities of 35 to 250

tons per day. The commenter (IV-D-08) notes that, however, the emission guidelines require State

plans to address Class A and B units that have plant combustion capacity greater than 250 tons per

day. The commenter (IV-D-08) states that since Class A and B units appear to have no upper

capacity limit, they seem to be large MWC units.

Response: The EPA believes the commenter misread the applicability section of

Subpart BBBB (§60.1550). The proposed emission guidelines (40 CFR part 60, Subpart BBBB) and

associated State plans apply to each small MWC unit, which is defined as an MWC unit with a

combustion design capacity of 35 to 250 tons per day. MWC units greater than 250 tons per day are

covered by the large MWC unit emission guidelines (40 CFR part 60, Subpart Cb), associated State

plans, and the large MWC unit Federal plan (40 CFR part 62, Subpart FFF). MWC plants with

multiple small units could have an aggregate plant capacity larger than 250 tons per day, but because all

units are less than 250 tons per day, the units would be subject to Subpart BBBB.
36

Comment: Two commenters (IV-G-02, IV-F-1f) requested that EPA clarify the definition of

“modification or modified municipal waste combustion unit” (§60.1940) to specifically exclude

expenditures made to comply with the rule. Additionally, one commenter (IV-G-02) believes that a

facility owner should not be penalized if modifications intended to comply with the rule are undertaken

more than 6 months prior to promulgation. One commenter (IV-G-02) suggested that EPA expand the

parenthetical expression in the definition of “modification or modified municipal waste combustion unit”

to read “(not including the cost of land and air pollution control and monitoring equipment and

systems).”

Response: Section 1550(c) of the emission guidelines (40 CFR part 60, Subpart BBBB) states

that if you make a physical or operational change to an existing municipal waste combustion unit

primarily to comply with your State plan, then the NSPS (40 CFR part 60, Subpart AAAA) does not

apply to that affected facility. This is consistent with the definition of MWC unit in §60.1940 of

Subpart BBBB, which states that the MWC unit does not include air pollution control equipment. 

Therefore, modification to equipment that falls outside the definition of a combustion unit would not

need to be apportioned to the MWC unit when considering modification/reconstruction (see

Section 3.3 of 1995 BID). 

Comment: One commenter (IV-D-18) suggested that EPA modify the rule to clarify that

multiple MWC units will not be treated as a single MWC unit merely because multiple MWC units

share some components (§60.1940). Based on EPA’s distinction in the proposed rule between MWC

units and plants, the commenter (IV-D-18) believes that EPA did not intend for multiple units with

shared components to be classified as a single MWC unit for the purpose of determining applicability

under this rule.

Response: The EPA agrees that it does not intend for multiple units with shared components to

be classified as a single MWC unit for the purpose of determining applicability under this rule. The

emission guidelines (40 CFR part 60, Subpart BBBB) and associated State plans apply to each small

MWC unit as it is defined in §60.1940 of Subpart BBBB and no regulation change is necessary (see

Section 3.3 of 1995 BID).

Comment: One commenter (IV-D-18) requested that EPA clarify whether its MWC units

would be classified as modular excess-air units or mass burn refractory units. The commenter

(IV-D-18) suggested that EPA define “field-erected.” The commenter (IV-D-18) noted that its MWC
37

units were purchased and assembled as modular units and have since been significantly rebuilt. The

commenter provided a list of significant changes made to the units. 

Response: This is a very site-specific question and the commenter should contact its EPA

Regional Office for a final applicability determination. The commenter operates three Class II MWC

units and with the exception of carbon monoxide (CO), Class II units have the same emission limits

regardless of combustor type. 

Comment: One commenter (IV-D-18) recommended that EPA raise the lower size limit cutoff

to 39 tpd (§60.1550) to be consistent with the 1994 proposed and 1995 final rule (40 CFR part 60,

Subpart Cb). The commenter (IV-D-18) noted that all of EPA’s analyses regarding the prior rule were

based on 35 Mg/day, which is roughly 39 tpd. The commenter (IV-D-18) noted that nothing in the

proposed rule for small MWC units indicates that EPA has made any new analyses based on the new

lower production rate of 35 tpd. The commenter (IV-D-18) believes that this change could affect

EPA’s determination of emission standards and MACT limits, as well as the economic costs associated

with the proposed rule.

Response: The MACT floor analysis and economic impact analysis for the small MWC unit

emission guidelines are based on the lower size cutoff of 35 tpd on an individual unit capacity basis

(Docket No. A-98-18). The EPA investigated a new lower size cutoff and determined that a lower

size cutoff of 35 tpd would have the least impact on the number of sources affected by the NSPS and

emission guidelines (Docket No. A-98-18). The 1995 MWC rulemaking was based on a 39 tpd

cutoff, based on aggregate plant capacity, not individual unit capacity.

4.3 SELECTION OF MAXIMUM ACHIEVABLE CONTROL TECHNOLOGY

4.3.1 General Comments on Emission Levels

Comment: One commenter (IV-D-25, IV-D-22) recommended that the subcategories should

be consolidated into one class of small MWC units with one set of limits for new and existing facilities. 

The commenter (IV-D-25, IV-D-22) stated that this can be achieved using technologies that are

currently available and operating in the U.S. and abroad. The commenter (IV-D-25, IV-D-22) stated

that combining classes would greatly simplify the rule and place it more in line with emission limits

currently in place in other heavily industrialized countries. The commenter (IV-D-25) stated that, based
38

on the availability of technology, the limits for all metals (i.e., cadmium and lead), particulate matter,

HCl and SO2 for existing units should be established at the levels proposed for new units. 

Response: Section 129 requires that separate regulations must be developed for new MWC

units and existing MWC units and specifies different criteria for determining the MACT floors for new

versus existing units. Section 129 allows different emission limits for new versus existing sources. The

EPA believes the subcategorization and emission limits in the final regulations for new and existing

MWC units have been determined appropriately. 

Comment: Several commenters (IV-D-12, IV-D-26, IV-D-25, IV-D-22) believe that the

emission guidelines for the proposed Class B incinerators are not stringent enough and should be

revised to be as stringent as those for the proposed Class A incinerators. Two commenters (IV-D-12,

IV-D-26) stated that stricter emission standards have, and will continue to lead to more efficient and

cheaper technology. The commenters (IV-D-12, IV-D-26) believe that the science of emission

controls is market driven and that the (air pollution control) market should be driven toward the more

strict proposed Class A emission standards. Two commenters (IV-D-28, IV-D-26) do not believe

that a less stringent dioxin emission limit for the proposed Class B units is justified. One commenter

(IV-D-25, IV-D-22) stated that the technology currently exists for all classes of small MWC units to

easily achieve the most stringent (Class A) of the proposed levels for all pollutants. The commenter

(IV-D-25, IV-D-22) stated that this is especially true for the proposed Class B and C emission limits. 

The commenter (IV-D-25, IV-D-22) stated that based on available technology the organics emissions

limits for the proposed Class B and C units should be as stringent as those established for the proposed

Class A units.

One commenter (IV-G-06) believes that the proposed Class B SO2 and HCl emission limits

are too stringent and that these emission limits should be revised to equal the proposed Class C

emission limits. The commenter (IV-G-06) stated that both classes of units are controlled using the

same technology and both classes burn similar waste streams. Therefore, the commenter (IV-G-06)

concluded that the expected concentrations of SO2 and HCl for both classes should be the same. 

Several commenters (IV-D-21, H2, IV-F-1c, IV-F-1d), representing three separate waste-toenergy facilities, stated that their MWC units currently do not meet the proposed Class A emission

limits. Commenters (H2, IV-F-1c, IV-F-1d) stated that these plants would be required to add a spray

dryer in order to meet the proposed Class A SO2 and HCl emission limits. Other commenters
39

(IV-D-27, IV-G-15) stated that their fluidized bed combustion units would not be able to comply with

many of the proposed Class A emission limits, especially the limits for PM and HCl, without postcombustion control.

Response: Section 129 of the CAA allows the EPA, at its discretion, to establish different

emission limits for different subcategories. In the final emission guidelines, the proposed Classes A and

B have been combined into one subcategory with one set of emission limits. The final Class I

comprises the proposed Class A and B units. Class I are small MWC units located at plants with an

aggregate plant capacity greater than 250 tons per day of MSW. The EPA believes there is no longer

a technical need for having separate Class A and B designations (Docket No. A-98-18). Class C

units, which are renamed Class II units in the final emission guidelines, remain a separate subcategory,

as in the 1995 emission guidelines, with their own set of emission limits. The subcategorization in the

final emission guidelines is consistent with the 1995 rulemaking (40 CFR part 60, Subpart Cb) and

EPA believes that this subcategorization is valid. 

Comment: Several commenters (IV-D-14, IV-D-28, IV-D-05, IV-D-15, IV-D-26,

IV-D-09) believe that, because of the dilution of flue gas, the proposed Class B emission limits should

be set more stringent than the proposed Class A emission limits, not less stringent. These commenters

(IV-D-14, IV-D-28, IV-D-05, IV-D-15, IV-D-26, IV-D-09) believe that if a proposed Class B

refractory type incinerator produces 50 percent more flue gas than a proposed Class A unit, then it

would release more pollution on a mass basis. One commenter (IV-D-14) believes that MWC units in

the proposed Class B would be able to meet the emission limits by dilution of the flue gas. Another

commenter (IV-D-28) recommended that the emission limits should be either designated as a limit on

the total mass released or as a concentration corrected for the dilution. The commenter (IV-D-28)

believes that it would be possible for a proposed Class B MWC plant to release over 500 percent

more mass of dioxins than a proposed Class A plant. 

Response: In these final emission guidelines, the proposed Classes A and B have been

combined into a single Class I subcategory (small MWC units located at plants with an aggregate plant

capacity greater than 250 tons per day of MSW), with one set of emission limits. The EPA believes

there is no longer a technical need for having Class A and B limits and that flow rates for the two types

of MWC units are, in fact, similar (Docket No. A-98-18). The subcategorization in the final emission

guidelines is consistent with the 1995 rulemaking (40 CFR part 60, Subpart Cb) and the EPA believes
40

that this subcategorization remains valid. Because there is no technical difference and because the

purpose of this rulemaking is to reestablish emission guidelines for existing small MWC units with

combustion capacities of 35 to 250 tons per day of MSW, EPA is retaining the subcategorization used

in the 1995 emission guidelines.

Comment: One commenter (IV-D-08) stated that all of the emission limits, except acid gases

and lead, are more stringent than the recent emission guidelines for hospital, medical, infectious waste

incinerators (HMIWI). The commenter (IV-D-08) also stated that the Class C unit emission limits

should be no less stringent than the large size HMIWI emission limits. 

Response: The EPA agrees that small MWC units and HMIWI units are similar in some

respects, however, these are different source categories and must be addressed in separate

rulemakings. There is no technical or legal basis for these two source categories to have the same

limits. The small MWC rules and the HMIWI rules are technology based standards and different

source categories will lead to different MACT floors and MACT emission limits for each source

category. The goal of this rulemaking is to reestablish the 1995 emission guidelines for small MWC

units. 

Comment: One commenter (IV-D-25) recommended that the percent reduction option for

SO2 and HCl be eliminated and compliance be based on achieving the specified emission limit at the

stack. 

Response: The percent reduction option for meeting the SO2 and HCl emission limits was

included in the 1995 emission guidelines (40 CFR part 60, Subpart Cb). The MACT standards are

based on achievable performance levels of control technologies, and as documented in the support for

the 1995 rules, all MWC units with the MACT acid gas control technologies can meet either the

specified percent reductions or the outlet concentration level. However, either the percent reduction or

the outlet concentration level alone might not be achievable in all cases, because variations in inlet

concentration can affect the achievable percent reduction or outlet concentration levels. The goal of this

rulemaking is to reestablish emission guidelines for small MWC units; therefore, EPA is retaining the

percent reduction option for meeting the SO2 and HCl emission limits. 
41

4.3.2 Municipal Waste Combustor Organics

Comment: One commenter (IV-D-25) questioned why EPA was proposing dioxin limits

(which do not require compliance for 3 to 5 years) at levels that are up to 12 times higher than currently

required in other areas. The commenter (IV-D-25) pointed out that in Europe and Japan dioxin limits

for existing facilities have been set as low as 0.1 ng TEQ/Nm3 (~10 ng/Nm3 on a total mass basis,

according to the commenter’s conversion).

Response: The final MWC emission guidelines are technology based standards required by

Section 129 of the CAA. The standards for small MWC units are set at the demonstrated performance

levels of the best-performing MWC units based on EPA’s judgement and do not have to be identical to

regulations in different countries. These demonstrated performance levels are the same demonstrated

performance levels contained in the 1995 emission guidelines (40 CFR part 60, Subpart Cb). 

Additionally, it is difficult to directly compare non-U.S. and U.S. test data due to difference in test

methods, QA standards, reporting methods, and compliance policies. Given these differences, the

EPA chose to principally rely on the reasonably large pool of performance and permit data from

domestic plants in making this determination (see Section 3.4.1 of 1995 BID).

Comment: One commenter (IV-D-25) stated that there is no technical basis for allowing a

higher organics emission limit for a unit when an ESP is installed in the system. The commenter

(IV-D-25) requested that EPA include only one organics emission limit for the proposed Class A units.

Response: The dioxins/furans levels proposed for both ESP and FF-based systems are more

stringent than the MACT floor, and are the same as those in the 1995 promulgated rule. Test data

have shown that MWC units equipped with an SD/FF/CI air pollution control system achieve better

dioxins/furans emission reductions than SD/ESP/CI systems. The preamble for the 1995 rule (60 FR

65401) explains the rationale for selecting the MACT standards including the SD/FF-based and

SD/ESP-based emission limits, considering factors specified in Section 129 such as the cost of

achieving the emission reductions. The purpose of this rulemaking is to reestablish emission guidelines

for small MWC units and EPA is retaining the proposed format for the dioxins/furans emission limit,

consistent with the 1995 rulemaking (see Section 7.5.2 of 1995 BID).
42

4.3.3 Municipal Waste Combustor Metals (other than Mercury) and Particulate Matter

Comment: One commenter (IV-D-18) reasoned that, since the rule has limits for mercury, lead

and cadmium, there is no need for a PM limit. The commenter (IV-D-18) stated that, if the EPA

retained the PM limit, it should be raised to 180 mg/dscm. 

Response: Section 129(a)(2) of the CAA requires an emission limit for PM and eliminating the

emission limit for PM is not an option. Furthermore, a PM limit of 180 mg/dscm suggested by the

commenter is not possible because the MACT floors for PM for all classes of small MWC units are at

levels lower than 180 mg/dscm, and Section 129 does not allow standards that are less stringent than

the MACT floor (see Section 7.5.3 of 1995 BID). 

4.3.4 Nitrogen Oxides Emission Limit

Comment: One commenter (IV-D-25) stated that, based on current technology, all units,

regardless of size or design, should be required to control oxides of nitrogen. The commenter

(IV-D-25) stated that, at a minimum, NOX limits should be established at a level based on the

equivalent of a 50 percent reduction for all MWC units. The commenter (IV-D-25) asserted that this

level of control is easily achievable with currently available technology and is being demonstrated on

small MWC units in Europe and Japan as well as on many types of small combustion processes in the

U.S. One commenter (IV-F-1g) requested that EPA apply the large unit nitrogen oxide emission limit

to the small rotary waterwall units. The commenter (IV-F-1g) pointed out that large MWC units under

the 1995 emission guidelines (Subpart Cb) are subject to a nitrogen oxide emission limit of 180 ppmv

(corrected to 7 percent oxygen) for the rotary waterwall units, whereas small MWC units under the

current emission guidelines (Subpart BBBB) would be required to meet a 171 ppmv limit for nitrogen

oxide (corrected to 7 percent oxygen). Two commenters (IV-D-03, IV-G-03) requested that EPA

establish nitrogen oxide limits for the proposed Class A small MWC units for the emissions guidelines

that are no more restrictive than the nitrogen oxide emission limits for large MWC units. One

commenter (IV-D-03) disagreed with setting a single nitrogen oxide emissions limit for all types of small

MWC units within the proposed Class A. Both commenters (IV-D-03, IV-G-03) believe that the

standards appear to be more stringent for certain units than the emission standards set in 1995 for large

MWC units (see Section 7.6.2 of 1995 BID).
43

Response: The final Subpart BBBB includes NOX emission limits for Class I units based on

combustor type. (The final Class I comprises the proposed Class A and B units.) The EPA

recalculated NOX MACT floor levels by combustor type (Docket No. A-98-18). The combustor

types are the same as those used for the MWC units in the 1995 rules, except modular starved air and

modular excess air are now identified, rather than placed in an “other” category.

The 1999 proposal included a single NOX emission limit of 171 ppm. The final NOX emission

limits, based on combustor type, range from 170 to 380 ppm for Class I units, which are essentially the

same as the 1995 emission limits, with three exceptions. For mass burn rotary combustors, fluidized

bed combustors (FBC), and modular excess air combustors (MOD/EA), the new MACT floors are

lower than the 1995 MACT floor and the final NOX limit for three combustor types are more stringent

(170 ppm vs 250 ppm for mass burn rotary, 220 ppm vs 240 ppm for FBC, and 190 ppm vs 200 ppm

for MOD/EA). Additionally, there is a new NOX limit of 350 ppm for mass burn refractory units. The

EPA rounded the final MACT floor to two significant figures before setting the MACT limits as

previously done in setting the 1995 NOX standards. Available NOX test data indicate the final emission

limits have been achieved by these combustor types. The EPA analyses for the 1995 regulation, data

contained in background information documents, data in the docket, and comments submitted by air

pollution control vendors indicate that the limits are achievable for all Class I units of all combustor

types (A-98-18).

Comment: Two commenters (IV-D-03, IV-F-1g) requested that emissions averaging and

trading for nitrogen oxide limits be permitted for the emission guidelines for small MWC units. The

commenter (IV-D-03) believes that allowing large MWC plants this option in Subpart Cb, but not

allowing plants with small MWC units this option, imposes an unfair restriction on small plants.

Response: NOX averaging would greatly increase the complexity of the small MWC rule.

Additionally, NOX averaging was not used by any States in their State plans implementing the

1995 emission guidelines for large MWC units. Consequently, NOX averaging was not added to the

final emission guidelines for small MWC units. Although NOX averaging is not included in the final

guidelines, a State plan can include emissions averaging if it is demonstrated to be as protective as the

guidelines. Thus, under authority of Section 129, a State could develop and submit a NOX emissions

averaging plan as long as it demonstrates the plan is as protective as the guidelines. 
44

4.3.5 Good Combustion Practices

Comment: One commenter (IV-G-04) requested that EPA amend the operator training course

requirement so that it only applies to employees with responsibilities that affect how a municipal waste

combustion unit operates. The commenter (IV-G-04) believes that not all of the positions listed in the

proposed §60.1655 exist at the commenter’s facility or affect the operation of the commenter’s MWC

units. In addition, the commenter (IV-G-04) believes that it seems an unnecessary administrative and

recordkeeping burden to require MWC operators to train employees in areas where the employee has

no operating responsibility or control. 

Response: The EPA is retaining the operator training course requirement in §60.1655 as

proposed. The EPA believes it is important for all personnel affecting the operation of the plant to

understand the interrelationship between different operations and how they affect emissions. The

training requirements in §60.1655 are the same as those in the 1995 regulations that are reestablished

by this rulemaking.

Comment: One commenter (IV-D-10) requested that EPA amend §60.1675 to allow

alternative plans for site-specific examinations for operator full certification that ensure operator

qualifications at a reasonable cost. The commenter (IV-D-10) noted that the costs of a site-specific

examination through the ASME is $5,000 or more per operator, if the operator passes the first time. 

The commenter (IV-D-10) believes that a small MWC facility could use these financial resources more

productively to serve the public. The commenter (IV-D-10) provided the following amendment to

§60.1675: “The Administrator may approve alternate plans for site-specific examinations for operator

full certification that ensures operator qualifications at a reasonable cost.”

Response: The EPA is retaining the operator certification provisions in §60.1675 as proposed. 

However, under the general provisions (40 CFR part 60, Subpart A), the Administrator can approve

alternative plans for operator certification. The operator must apply to the Administrator with a

proposal for an alternative plan for operator certification. Until the alternative is approved, however,

the operator needs to comply with the training requirements as written.

Comment: One commenter (IV-D-18) recommended that the full certification requirement for

Class C (renamed Class II in final emission guidelines) shift supervisors be deleted (§60.1675). The

commenter (IV-D-18) believes that this requirement is excessive, especially for a small, Class C facility. 
45

The commenter (IV-D-18), who is located in Texas, believes that sending multiple employees to the

east coast is unnecessarily expensive for the operator of a Class C facility.

Response: The EPA believes that operator certification is important and is not removing the

operator certification requirement for any class of small MWC units. However, an operator may apply

to the Administrator with a proposal for an alternative plan for operator certification. Until the

alternative is approved, however, the operator needs to comply with the training requirements as

written. 

Comment: One commenter (IV-G-05) questioned the operator substitution requirement in

§60.1195 of Subpart AAAA and §60.1685 of Subpart BBBB. The commenter (IV-G-05) has

commenced the certification of supervisors and control room operators in an effort to avoid shut down

of the facility and requested clarification or amendment to the rule before completing the process. 

Response: The commenter (IV-G-05) misread the requirements for operator substitution. The

commenter later submitted a letter (IV-G-17) withdrawing the original comment letter. 

Comment: Three commenters (IV-G-05, IV-F-1g, IV-G-14) requested that EPA revise

§60.1685 to reflect the typical work schedule for operators, which is a 12-hour shift. One commenter

(IV-D-03) noted that this change would mean that when certified operators are offsite for less than 12

hours (rather than 8 hours), the provisionally certified control room operator may function in his/her

place; and when provisionally certified operators have to substitute for fully certified operators for 12

hours or more, the substitution must be documented. The commenter (IV-D-03) also requested that

EPA clarify the boundary limits of §60.1685. 

Response: The EPA agrees with the commenter that a 12-hour shift is more typical for MWC

operators. The EPA revised §60.1195(a) and (b) of Subpart AAAA and §60.1685(a) and (b) of

Subpart BBBB to reflect a 12-hour shift, rather than an 8-hour shift. The EPA revised the

recordkeeping requirements in §60.1410(l) of Subpart AAAA and §60.1885(l) of Subpart BBBB so

that they apply when all chief facility operators and certified shift supervisors are offsite for more than

12 hours. In addition, EPA revised the regulation to clarify the boundary limits in §60.1685 of

Subpart BBBB and §60.1195 of Subpart AAAA as "12 hours or less" and "2 weeks or less". 

Comment: One commenter (IV-D-11) requested that EPA amend §60.1685 to provide

criteria on why a corrective action may be approved or disapproved. The commenter stated that in the

absence of any such criteria, the 90-day operation limit after disapproval should be extended to 6-12
46

months. The commenter (IV-D-11) believes that the 90-day shutdown provision may not allow

sufficient time to meet the certified operator, shift supervisor, or chief facility operator requirement.

Response: The EPA believes that the requirements are adequate and no change is needed. 

The Administrator can approve an operating extension as long as the facility operator is making

progress towards filling the position with a certified operator.

Comment: One commenter (IV-D-18) recommended that EPA delete the temperature

requirement at the inlet of the PM control device (§60.1690). The commenter (IV-D-18) believes this

requirement is redundant and unnecessarily restrictive because the use of a carbon injection system will

minimize any increase in dioxins/furans resulting from high temperatures in the ESP. The commenter

(IV-D-18) needs the ability to allow slight increases in temperature at the inlet to the ESP to ensure

adequate combustion of municipal waste.

Response: The EPA believes that monitoring the temperature at the inlet to the PM control

device is important to ensure that conditions that promote dioxins/furans formation do not occur. 

Therefore, EPA is not deleting this requirement (see Section 3.5.6 of 1995 BID).

Comment: Two commenters (IV-D-27, IV-G-02) suggested that EPA revise footnote b of

Table 5 of Subpart BBBB to be consistent with the long term CO analysis memorandum in Docket

No. A-98-18. The proposed footnote b to table 5 states that all averages are block averages,

however, according to the memorandum in the docket (item II-B-8), EPA established the 200 ppm

limit as a 24-hour geometric mean average concentration (rather than an arithmetic average). One

commenter (IV-G-02) requested that EPA add a footnote to Table 5 of Subpart BBBB that applies to

“Fluidized bed, mixed fuel, (wood/refuse-derived fuel)” and “Mass burn rotary waterwall,” and reads:

“c. 24-hour daily block geometric average concentration.”

Response: The EPA corrected Table 5 to Subpart BBBB to clarify that the averaging time for

Fluidized bed, mixed fuel, (wood/refuse-derived fuel) should read “24-hour geometric mean” and

footnote b should read “Block averages. See §60.1940 for definitions.” This was an inadvertent error

and the correction is consistent with the CO analysis memo in Docket No. A-98-18. The averaging

time and method for mass burn rotary waterwall is correct as published and is consistent with the final

1995 emission guidelines, which are being reinstated.

Comment: One commenter (IV-D-16) requested that EPA provide additional operating

practice requirements based on the compliance assurance monitoring (CAM) rule. The commenter
47

(IV-D-16) noted that any standard or other requirement governing solid waste incineration, under

Section 129 of the CAA, is an applicable requirement for Title V. The commenter (IV-D-16) noted

that to promote consistency among the various State Title V permits, it would be beneficial if the EPA

could propose operating requirements for commonly used MWC metal, PM, and acid gas controls. 

These operating requirements would have to satisfy the requirements of the CAM. 

Response: Compliance with the requirements of the CAM rule (40 CFR 64.1 through 64.10)

is beyond the scope of this rulemaking. However, the small MWC emission guidelines already include

operating requirements for commonly used MWC metal, PM, and acid gas controls.

Comment: One commenter (IV-D-16) recommended that EPA should check to make sure

that the proposed operating requirements for dioxins/furans and mercury are consistent with other rules

for similar source types. The commenter (IV-D-16) noted that 40 CFR part 60, Subpart EEE or the

Hazardous Waste Incinerator MACT specifies operating requirements for carbon injection, including

carbon injection rate, carrier fluid flowrate or pressure drop, and carbon specification. The commenter

(IV-D-16) recommended that EPA consider if carbon injection rate, as proposed, is sufficient to

provide assurance of compliance with the dioxins/furans and mercury standards.

Responses: The EPA could have developed several different control device operating

requirements to limit dioxins/furans and mercury emissions. The proposed requirements are the same

as the 1995 requirements and the EPA believes they are adequate to limit dioxins/furans and mercury

emissions. The operating requirements that are contained in other rules are beyond the scope of this

specific rulemaking. 

Comment: One commenter (IV-D-18) believes that the proposed CO limit of 50 ppmv, based

on a 4-hour average, for modular starved air and modular excess air MWC units should be raised to

100 ppmv. The commenter noted that the CO limits for mass burn type MWC units is 100 ppmv and

argued that the same reasoning supporting a 100 ppmv limit for mass burn MWC units applies to the

modular MWC units. The commenter noted that EPA’s data for modular MWC unit included CO

spikes over 100 ppmv and CO levels from their own modular MWC units were generally below 30

ppmv with occasional spikes over 50 ppmv.

Response: The proposed CO limits are the same as those that were included in the 1995

MWC regulations, which are being reestablished by this rulemaking. The CO limits in the 1995
48

regulations were supported by the data collected and available in 1995 and EPA judged the CO limits

to be achievable. Therefore, the final CO limits are the same as the proposed CO limits.

Comment: One commenter (IV-D-27) suggested that EPA add a footnote to the CO limit in

Table 5 of Subpart BBBB to state that the CO limit does not apply during any period longer than one

hour when the unit is combusting fuel with an RDF content of less than 30 percent on heat input basis. 

The commenter believes this exemption would be in line with the exemption for “co-fired” units

(§60.1555(g)) and the 1995 BID. The commenter (IV-D-27) suggested that this approach would

address situations where their wood/RDF-fired unit will burn only wood for a portion of each day and

could have trouble meeting the CO limits during this period. 

Response: The format of the current CO limits is the same as the format in the final

1995 regulations. The EPA believes that the CO format is still valid for this rulemaking, which

reinstates the 1995 regulations, and no change is necessary. The regulation already addresses co-fired

units (§§60.1555 and 60.1940).

4.3.6 Size Categories of Existing MWC Units

Comment: One commenter (IV-G-04) expressed support for the subcategories and the

rationale for selecting the subcategories. Another commenter (IV-D-15) did not support the proposed

Class A, B, and C subcategories and recommended that EPA either combine the proposed classes of

existing small MWC units and promulgate regulations for them as one category or promulgate

regulations for subcategories based on aggregate plant capacity of 250 tons per day.

One commenter (IV-D-25, IV-D-22) stated that there is no health or technological basis for

EPA’s decision to subcategorize the existing MWC units based on overall facility size. The commenter

(IV-D-25, IV-D-22) recommended that EPA reconsider the proposed subcategories and emission

limits based on actual operating data. The commenter (IV-D-25, IV-D-22) provided data to support

its recommendation. The commenter (IV-D-25, IV-D-22) stated that the technology currently exists

for all sizes of small MWC units to easily achieve the most stringent of the proposed levels for all

pollutants. Another commenter (IV-G-03) recommended that EPA should not subcategorize based on

aggregate capacity, but should subcategorize based on type (refractory or non-refractory). 

Response: The EPA agrees that the subcategorization could be done in different ways. 

However, in the 1995 NSPS and emission guidelines (40 CFR part 60, Subparts Eb and Cb), the EPA
49

elected to use an aggregate plant capacity of 250 tons per day to subcategorize small MWC units. The

EPA believes that approach is one valid way to subcategorize, and notes that Section 129 allows

subcategorization based on size. Because the purpose of this rulemaking is to reestablish the 1995

NSPS and emission guidelines for new and existing small MWC units with combustion capacities of 35

to 250 tons per day of MSW, EPA is retaining the subcategorization used in the 1995 NSPS and

emission guidelines (i.e., Class I and Class II).

4.3.7 Classes of Existing MWC Units

Comment: One commenter (IV-G-04) expressed support for the subcategories and the

rationale for selecting the subcategories. One commenter (IV-G-03) did not support subcategories

based on aggregate plant capacity and recommended that EPA subcategorize based on type of unit,

either non-refractory or refractory. Other commenters (IV-D-05, IV-D-15, IV-D-21) disputed the

technical differences between the proposed Class A (non-refractory) and Class B (refractory). Other

commenters (IV-G-06, IV-D-27, IV-D-21, IV-D-17, IV-G-15, IV-G-13, IV-F-1d, IV-F-1e)

requested that EPA either reclassify specific MWC units or create a new subcategory for specific

MWC units based on the type or design of the units.

Several commenters (IV-D-05, IV-D-15, IV-D-21) stated that the difference between flue gas

per ton of MSW is not a valid reason to set the proposed Class B emission limits higher than Class A. 

Another commenter (IV-D-17) stated that there is no apparent benefit for distinguishing between the

proposed Class A and B. Two commenters (IV-D-14, IV-D-17) believe that the proposed Class B

units can apply a similar control technology as the proposed Class A and should be able to achieve the

proposed Class A emission levels regardless of flow rate. One commenter (IV-D-21) stated that EPA

has inappropriately distinguished the proposed Class A and B units on the basis of a technological

difference (refractory vs. nonrefractory) that is without significance, and has ignored other, more radical

technological differences that result in actual differences in emission characteristics and control

alternatives. The commenter (IV-D-21) stated that EPA’s analysis of the combustion characteristics

that make up the population of the proposed Class B is erroneous (referenced II-B-9) and based on

outdated data (referenced 1969 publication titled “Municipal-Scale Incinerator Design and

Operation”). 
50

Several commenters (IV-D-21, IV-D-17, IV-F-1d, IV-F-1e) stated that rotary waterwall

MWC combustor types should be included in the proposed Class B or in a separate class. One

commenter (IV-D-21) stated that rotary waterwall combustors are also inappropriately categorized in

the proposed Class A because they are a completely different technology than other units in the

proposed Class A. Several commenters (IV-D-21, IV-F-1a, H2, IV-F-1c) provided background

information on two waste-to-energy facilities. Four commenters (IV-D-21, IV-D-17, IV-F-1d,

IV-F-1e, IV-F-1g) stated that the O’Connor rotary waterwall combustion technology, on which these

two waste-to-energy facilities are based, has distinguishing characteristics that would provide a rational

basis for categorizing units utilizing this technology separately from the current assortment of facilities in

the proposed Class A. Two commenters (IV-D-21, IV-F-1d) described the design characteristics of

the O’Connor rotary waterwall combustion technology to show that there are distinct differences

between them and other types of combustors that are currently grouped under the proposed Class A in

the emission guidelines. Commenters IV-D-21, IV-D-17, IV-F-1d, and IV-F-1e provided

documentation to support their requests.

Two commenters (IV-D-27, IV-G-06) requested that EPA reclassify RDF/fluidized bed

combustors as Class B units. One commenter (IV-D-27) initially requested that EPA create a new

subcategory for RDF/wood-burning fluidized bed combustors or, alternatively, reclassify these units as

Class B units. The same commenter (IV-G-15) later stated that placing these combustors in either the

proposed Class A or the proposed Class B would be inequitable. The commenter (IV-G-15)

requested that EPA create a separate subcategory for RDF/fluidized bed combustors and provided

information to support the request.

One commenter (IV-G-06) stated that RDF/fluidized bed units are Class B refractory units

and, therefore, have been improperly classified as Class A nonrefractory units in the inventory. The

commenter (IV-G-06) stated that these units are characterized by much higher excess air levels than

typically found in non-refractory MWC units and the structure is protected by refractory and not

closely spaced steel tubes that have water continuously flowing through them. 

Another commenter (IV-D-20) requested that EPA create a new subcategory for Inclined

Fluidized Bed (IBF), irrespective of aggregate plant capacity. Commenters IV-G-06, IV-D-27,

IV-D-20, and IV-G-15 provided documentation to support their requests.
51

Response: The EPA agrees that the subcategorization could be done in different ways. In the

final emission guidelines, the proposed Classes A and B have been combined into Class I (small MWC

units located at plants with an aggregate plant capacity greater than 250 tons per day of MSW. Class

C units (small MWC units located at plants with an aggregate plant capacity less than or equal to 250

tons per day of MSW) remain as proposed, except they are renamed as Class II in the final emission

guidelines. The EPA believes there is no longer a technical need for having Class A and B separate and

that flow rates for these types of MWC units are, in fact, similar (Docket No. A-98-18). This

subcategorization is consistent with the 1995 NSPS and emission guidelines (40 CFR part 60, Subparts

Eb and Cb) and EPA believes that this subcategorization is a valid way to subcategorize. Because the

purpose of this rulemaking is to reestablish the 1995 emission guidelines for existing small MWC units

with combustion capacities of 35 to 250 tons per day of MSW, EPA is retaining the subcategorization

used in the 1995 NSPS and emission guidelines.

4.4 IMPACTS OF MUNICIPAL WASTE COMBUSTOR EMISSION GUIDELINES 

Comment: One commenter (IV-F-1g) urged EPA to consider the significant cost of retrofitting

the proposed Class A facilities in the same manner as they did the units in the proposed Class B. 

Another commenter (IV-D-07) stated that the EPA should have analyzed and considered the

environmental benefits of combustion when setting the stringency of the emission limits, which the

commenter (IV-D-07) stated are far below the MACT floor and will discourage combustion. One

commenter (IV-G-07) expressed concern that the new rules and regulations go beyond the necessary

requirements and force major retrofit projects and added costs for small MWC facilities to operate in

compliance.

Commenters (IV-D-21, IV-F-1a, H2, IV-F-1c, IV-F-1e) representing two separate wasteto-energy facilities, stated that adding a spray dryer system to their facilities would be cost prohibitive. 

Commenters (H2, IV-F-1c, IV-F-1e) stated that these plants, which already have DSI control, would

be required to add a spray dryer in order to meet the proposed Class A SO2 and HCl emission limits in

the emission guidelines. Commenters (H2, IV-F-1c, IV-F-1e) stated that, in addition, there would be

adverse environmental impacts if their facilities were forced to close due to the regulation. Four

commenters (IV-F-1a, IV-F-1b, IV-F-1c, IV-F-1e) stated that the costs of adding a spray dryer to

each small MWC plant exceed the environmental benefits of a small decrease in SO2 and HCl
52

emissions. Several commenters (IV-G-07, IV-D-17, IV-F-1b, IV-F-1c) added that the control costs

associated with the regulation would drive their tipping fees up to the point where they would no longer

be able to compete in the marketplace. 

One commenter (IV-D-27) stated that EPA has performed no economic analysis for

RDF/wood-burning FB units for any purpose - not for initial categorization, nor for setting limitations

more stringently than the MACT floor. Two commenters (IV-D-27, IV-G-13) questioned how EPA

can meet its rulemaking obligations under the CAA without performing such analyses. 

One commenter (IV-F-1e) asserted that EPA’s economic analysis indicates that facility closure

and landfilling of waste is a potential and acceptable consequence of the economic impact of these

regulations. The commenter (IV-F-1e) stated that this seems inconsistent with EPA’s longstanding

hierarchy of solid waste management priorities.

Response: The proposed and final subcategories are based on technical considerations. 

These are technology based standards as required by Section 129 of the CAA. Section 129 does not

allow consideration of cost in establishing subcategories or setting the maximum achievable control

technology (MACT) floor. Cost and other impacts are considered only in determining whether to

require a control alternative more stringent than the MACT floor. The small MWC standards are set at

the demonstrated performance levels of the controls an MWC unit would require to meet the MACT

floor. These demonstrated performance levels are the same demonstrated performance levels

contained in the 1995 emission guidelines (40 CFR part 60, Subpart Cb), which is SD/FF for small

MWC units located at plants with an aggregate plant capacity greater than 250 tons per day of MSW

and DSI/FF for small MWC units located at plants with an aggregate plant capacity less than or equal

to 250 tons per day of MSW. Less control is not allowed under Section 129 of the CAA. The EPA

believes that the regulations for both the large and small MWC strike the correct balance between cost

to retrofit air pollution controls and emission reductions in making decisions of whether to require more

stringent control than the MACT floor (see Sections 7.5 and 7.6 of 1995 BID).

Comment: One commenter (IV-D-11) stated that EPA failed to consider that because DSI

systems do not contain flue gas cooling, small MWCs will need to add flue gas cooling to reduce

temperatures to achieve the mercury limit using CI. The commenter (IV-D-11) stated that the addition

of the flue gas cooling systems will come at considerable cost.
53

Response: The emission reduction potential of a DSI air pollution control system depends on

sorbent feed rate, type of PM control device, and flue gas temperature. The performance and cost of a

DSI system is documented in “Municipal Waste Combustors - Background Information for Proposed

Guidelines for Existing Facilities” (EPA-450/3-89-27e). The cost of adding temperature control is

already included in the cost of retrofitting a DSI-type of system that would be needed to meet the

dioxins/furans and other emission limits, and is therefore not included in the cost of retrofitting a CI

system (see Section 7.6.1 of 1995 BID).

4.5 PERFORMANCE TEST METHODS AND MONITORING PROVISIONS FOR

MUNICIPAL WASTE COMBUSTOR EMISSIONS

4.5.1 Continuous Monitoring

Comment: Four commenters (IV-G-01, IV-G-02, IV-G-07, IV-F-1f) requested that EPA

consider removing or revising the SO2 monitoring requirements for all small MWC facilities because the

costs for SO2 CEMS are not reasonable, relative to the amount of SO2 emitted from small MWC units. 

Two commenters (IV-G-01, IV-G-07) claimed that municipal solid waste is a low sulfur fuel and

removing the SO2 monitoring would be consistent with EPA policy for other low-sulfur fuels. One

commenter (IV-G-02) requested that EPA allow Class II facilities to use a work-practice monitoring

requirement similar to that for activated carbon, but applied to acid gas control reagent utilization, in

place of a requirement to use an SO2 CEM. A fourth commenter (IV-F-1f) stated that the CEMS

QA/QC and recordkeeping and reporting requirements for both SO2 and CO are onerous for Class II

facilities relative to the CO and SO2 emissions from these facilities.

Response: The EPA believes that the SO2 and CO monitoring contained in the proposed rule

is reasonable for known applications and the final rules retain those requirements. However, the

general provisions to part 60 (40 CFR part 60, Subpart A) allow the Administrator to approve

alternative or equivalent monitoring proposals, such as parameter monitoring for a control device, on a

case-by-case basis. The final rule clarifies that this flexibility exists for case-by-case application of

alternative monitoring.

Comment: Two commenters (IV-D-07, IV-G-14) recommended that EPA allow for

measuring unit load using alternative technologies that exhibit equivalent accuracy. The commenter

(IV-D-07) believes that load level control through steam flow measurement is appropriate, but the

ASME Power Test Code referenced in the proposal is specific to only one method of flow
54

measurement: an orifice or nozzle used in conjunction with a differential pressure measuring device. The

commenter (IV-D-07) noted that ASME PTCs do not address other technologies for flow

measurement. The commenter (IV-D-07) requested that flexibility be provided for those MWC units

that use other methods of measurement (e.g., annubar, vortex shedder, mag meters). 

Response: The general provisions to part 60 (40 CFR part 60, Subpart A) allow the

Administrator to approve alternative or equivalent monitoring proposals on a case-by-case basis. The

final rule clarifies that this flexibility exists.

Comment: One commenter (IV-D-07) recommended that the requirement for visual opacity

determination be waived if a properly certified and maintained continuous opacity monitoring system

(COMS) is in service. The commenter (IV-D-07) stated that EPA Reference Method 9 is a poor

substitute for a calibrated COMS. The commenter (IV-D-07) believes the requirement to measure

opacity by both performance testing using Method 9 as well as COMS will result in additional testing

expense without any corresponding benefit.

Response: Opacity measurement by EPA Reference Method 9 is the means for enforcement of

the opacity standards. However, the general provisions to part 60 (40 CFR part 60, Subpart A) allow

the Administrator to approve alternative test methods or waive testing on a case-by-case basis. 

Comment: Three commenters (IV-G-04, IV-D-20, IV-D-18) noted that some MWC facilities

with multiple combustion units share common steam generating and heat recovery systems. Therefore,

these facilities are unable to comply with the requirement for steam flow monitoring on an individual unit

basis, as required in §60.1810 of Subpart BBBB, because of the use of common heat recovery

equipment. For the plant, the steam flow is indicative of total facility steam flow rather than individual

combustion unit steam flow. In addition, one commenter (IV-D-20) noted that common air pollution

control equipment is usually used when common heat recovery equipment is used. In this case, the

facility cannot comply on a per-unit-basis with the continuous parameter monitoring requirements in

§§60.1715 and 60.1720 of Subpart BBBB, or routine performance testing of regulated emission

parameters. The commenter (IV-D-20) requested that the requirements for individual steam flow

monitoring, continuous emissions monitoring, and performance testing be revised to include provisions

for common steam generation and air pollution control systems with multiple combustion units. Another

commenter (IV-G-04) asked EPA to confirm whether the steam load monitoring requirements in

§60.1810(b) apply, instead of §60.1810(a), in cases where multiple units share a common steam
55

generator or heat recovery system. The final commenter (IV-D-18) asked the EPA to revise

§60.1810 to clarify that steam load in these situations can be monitored just downstream from the

steam drum just prior to the steam generator.

Response: The general provisions to part 60 (40 CFR part 60, Subpart A) allow the

Administrator to approve alternative or equivalent monitoring proposals on a case-by-case basis. The

final rule clarifies that this flexibility exists.

Comment: One commenter (IV-G-06) provided input on EPA’s efficiency measurement

method reported in the docket (Docket No. A-89-08, IV-B-22). First the commenter (IV-G-06)

stated that the recommended mathematical model must consider both reagent feed rate and the

concentration of the co-contaminant. According to the commenter (IV-G-06), these considerations are

necessary because both sulfur dioxide and hydrogen chloride are controlled by sorbent injection and

consume a portion of the reagent. The commenter (IV-G-06) believes that the model would be better

if it used the reciprocal of penetration versus terms that are proportional to reagent stoichiometry and

perhaps the squares and cross product of these terms rather than the efficiency and reagent flow rate. 

Response: The procedure contained in the docket for determining SO2 reduction efficiency is

only a supporting document and was not part of the proposed rule. Facilities that cannot measure SO2

or HCl concentrations at the control device inlet can apply for approval of alternative methods for

measuring or monitoring SO2 or HCl reduction efficiency under the general provisions (40 CFR part 60

Subpart A). Those alternative methods can include the commenter’s suggested changes to the EPA

procedure included in the docket.

Comment: One commenter (IV-G-04) asked for clarification as to whether the span values in

Table 7 of Subpart BBBB are minimum span values or if they are intended to reflect full span of the

instrument. This commenter (IV-G-04) stated that if they are intended as full span values, they do not

appear to be consistent with the referenced performance specifications (a table pertaining to this

comment was submitted with this comment). 

Response: The span values indicated in the table are the span values expressed as a

percentage of the hourly potential maximum concentration. However, on a case-by-case basis, the

owner or operator can deviate from the span values in the table by applying to the Administrator for

approval of alternative span values.
56

Comment: One commenter (IV-D-10) pointed out that a considerable cost is incurred each

time an emission test contractor has to be mobilized to the facility. This commenter (IV-D-10) stated

that the requirements under the proposed emission guidelines, in accordance with Appendix F of 40

CFR, would require on-site emission testing for quarterly relative accuracy testing of CEMs. The

commenter (IV-D-10) claims that quarterly calibration gas audits and relative accuracy audits for

CEMs would be substantially less costly without negative operational effects of harm to the

environment. 

Response: The commenter apparently has misunderstood the Appendix F requirements. For

most CEMS, Appendix F does not mandate quarterly stack testing for relative accuracy. For most

CEMS, one stack test per year, and three cylinder gas audits are used to determine relative accuracy.

Comment: In reference to §60.1690(c) and (d), one commenter (IV-D-11) suggested that

there should not be an absolute carbon usage limit because the total amount of carbon actually used and

the actual continuous feedrate can not be determined with sufficient accuracy to warrant an enforcement

action. This commenter (IV-D-11) explained that any total quarterly usage amount must include the

“live inventory” (i.e. actual carbon contained in the storage silo or bulk bags) and not just the amount

purchased and delivered. However, determining the absolute or remaining weight of the live inventory

is difficult. This commenter (IV-D-11) proposed that the absolute quarterly usage total be omitted and

that such information should only be a recordkeeping requirement and not used for enforcement action. 

This commenter (IV-D-11) also added that in addition to the requirement to report times when the

feedrate was not maintained, an additional check would be to require periodic feeder or feedrate

monitor calibration on a quarterly basis consistent with the CEM quarterly audits.

In addition, two commenters (IV-G-01, IV-G-07) noted that Minnesota has approved plans

that requires shift supervision and daily calibration of carbon injection feed rate, including quarterly

reporting to the State. The commenters (IV-G-01, IV-G-07) believe that to require additional carbon

usage information is irrelevant and duplicative. Another commenter (IV-G-14) suggested making

carbon/lime ratio and slurry density the reportable parameter. 

Response: Under the general provisions (40 CFR part 60 Subpart A), facilities can apply for

approval of alternative or equivalent methods for monitoring carbon feed rate. Because of variation in

plant and system configuration, it is not possible to anticipate all conceivable situations in the standards. 
57

The EPA believes it is better for facility operators to address site-specific issues on a case-by-case

basis.

Comment: One commenter (IV-D-11) recommended that §60.1720 be clarified to allow a

CO monitor to be located downstream of air pollution control equipment as long as the diluent monitor

(CO2 or O2) is located with it, which would be consistent with the Subpart Cb implementation

guidance. The commenter (IV-D-11) alleges that this would improve reliability and reduce

maintenance and CEM costs without sacrificing emission accuracy.

Response: Under the general provisions (40 CFR part 60 Subpart A), facilities can apply for

approval of alternative or equivalent methods for monitoring CO, including alternative placement of the

CO and diluent monitors. This alternative has already been approved for some large MWC units. The

final rule clarifies that this flexibility exists.

Comment: One commenter (IV-D-18) stated that the continuous emissions monitoring

requirement for SO2 contained in §60.1720 of the proposed emission guidelines is unnecessarily

redundant and should be deleted. The commenter (IV-D-18) claimed that the additional data acquired

through the use of a CEMS would not provide any additional useful operational information because of

the problems of attempting to adjust the injection system to respond to fluctuations in SO2 levels. The

commenter (IV-D-18) believes that if stack tests and parameter monitoring are sufficient for monitoring

hydrogen chloride, then they are sufficient for monitoring SO2. In conclusion, the commenter

(IV-D-18) suggested that a requirement to monitor some other parameter, like the sorbent feed rate for

a DSI/ESP system, would provide better information on the operation of an acid-gas control system.

Response: Under the general provisions (40 CFR part 60 Subpart A), facilities can apply for

approval of alternative or equivalent methods for monitoring SO2 emissions, including parametric

monitoring in place of an SO2 CEM. The final rule clarifies that this flexibility exists.

Comment: For the proposed emission guidelines, one commenter (IV-D-26) proposed that

EPA include parametric monitoring parameters to ensure compliance with other standards besides

dioxins/furans and mercury. This commenter (IV-D-26) suggested that the EPA develop guidelines for

continuous parametric monitoring of cadmium, lead, particulates, and hydrogen chloride. This

commenter (IV-D-26) noted that because continuous parametric monitoring will be required under Title

V, it is desirable for monitoring to be consistent from State to State, rather than each State developing

some different format. In addition, the new guidelines should be made consistent with other MACT
58

standards, such as the hazardous waste incinerator rule, which specifies the requirement for dioxin

control not only in regards to the carbon injection rate (as in the MWC guidelines), but also in relation

to carrier fluid flow rate/pressure drop and carbon specifications. 

Response: The proposed monitoring requirements are based on the available air pollution

control device and monitoring technology. The States are free to include more stringent requirements in

the State plans implementing the guidelines if they see fit to do so. Continuous parametric monitoring of

Cd, Pb, and PM is not needed because the control technology basis for the rule (fabric filtration)

operates in a continuous manner. Parametric monitoring is not needed for HCl because HCl and SO2

are controlled by the same technology and the rule requires monitoring of SO2 emissions. 

The carbon injection monitoring requirements for Hg control are the same as those that were in

the 1995 regulations and are sufficient to ensure control of other pollutants, such as dioxins/furans, that

are also affected by this technology. The EPA sees no need for additional monitoring requirements. 

Comment: One commenter (IV-D-15) requested that EPA require continuous emissions

monitoring for all regulated pollutants, including dioxins/furans, metals, volatile organic compounds, and

other toxics. The commenter (IV-D-15) believes that otherwise, there is no way of knowing what the

emission levels are on days when there is no stack test. The commenter (IV-D-15) believes that if

there were continuous monitoring for all pollutants, then sources would be less likely to challenge the

stack test methods. The commenter (IV-D-15) believes that States would be more likely to enforce

Notices of Violations if the State had continuous monitoring data, rather than relying on stack test

results that are challenged by sources.

Response: The proposed monitoring requirements are based on the continuous emission and

parametric monitoring systems that are now available and are adequate to ensure compliance. No

CEMS are available for dioxins/furans and metals (see Section 3.8.2 of 1995 BID).

Comment: Regarding CO monitoring, one commenter (IV-G-10) suggested that EPA change

the definition of response time to exclude sample extraction, conditioning and sample transport time but

only include analyzing and recording time. The commenter’s (IV-G-10) main concern is the 90-second

response time requirement. The commenter (IV-G-10) believes that the requirement may have been

included in PS4A as a “roll over” from the hazardous waste combustion monitoring requirement, where

CO is used for automatic waste feed shutoff. According to the commenter (IV-G-10), for MWC units,

CO monitors are not included in the automatic combustion control loop nor required for waste feed
59

shutoff. The commenter (IV-G-10) stated that CO monitors provide data that operators use to make

manual adjustments to minimize CO and meet Ea/Eb/Cb/proposed BBBB limits under the GCP

requirements. The commenter (IV-G-10) believes that for MWC applications, CO monitors do not

need rapid response times. In addition, the commenter (IV-G-10) states that due to the construction

sequence for installing new APC equipment to meet the Subpart BBBB requirements, new extractive

type CEMS would have to be installed in remote areas of the plant. According to the commenter

(IV-G-10), this results in relatively long sample transport times and makes meeting the PS4A response

time impossible. The commenter (IV-G-10) notes that most, if not all, CO monitors are extractive

systems to provide the necessary sensitivity and accuracy at typical low MWC CO levels. 

Response: The comments submitted on the CEMS response time for CO measurement under

revised PS4A are outside the scope of this small MWC rulemaking. However, the recent rulemaking

to update PS4A (signed by the Administrator on January 10, 2000) addressed comments received on

that PS4A rulemaking. In that PS4A rulemaking, the response time includes the time for gas sample

analysis and data reporting by the CEMS, and excludes the time required for gas sample extraction,

conditioning, or delivery to the CEMS as requested by the commenter. 

Comment: The commenter (IV-G-10) also believes that the high-level scale requirement

should be removed and replaced with a requirement that existing MWC units, which experience spikes,

would operate with a single scale that could accommodate higher emissions. The commenter

(IV-G-10) believes that new MWC units could still be required to have the second high level scale. 

The commenter (IV-G-10) recommended that the alternative relative accuracy criterion should

be changed to 5 ppm mean difference, rather than the current interpretation of 5 ppm as the sum of the

absolute values of the mean difference and confidence coefficient. According to the commenter

(IV-G-10), the NESCAUM CEM guidance document for MWCs jointly developed by the States and

EPA in 1990 used the mean difference only criterion. The commenter (IV-G-10) believes this criterion

was specifically developed to address the difficulties in getting two different measurement systems to

agree at low levels. 

Response: The comments submitted on the CEMS high-level CO scale requirements and the

CEMS relative accuracy requirement under revised PS4A are outside the scope of this small MWC

rulemaking. The recent rulemaking to update PS4A (signed by the Administrator on January 10, 2000)

addressed comments received on that PS4A rulemaking. 
60

Comment: One commenter (IV-D-18) suggested that EPA remove the COMS requirement,

or alternatively, that EPA add language to the rule clarifying that COMS data is to be used as

operational data rather than compliance data. The commenter (IV-D-18) believes that COMS are not

appropriate tools for measuring compliance with opacity limits, even at a 10 percent opacity limit. The

commenter (IV-D-18) believes that COMS do not accurately measure opacity during all situations and

that they are not appropriate for determining compliance. The commenter (IV-D-18) questioned why

EPA is requiring the reporting of “exceedances” based on COMS data, if compliance with the opacity

limit is going to be determined based on stack tests. 

Response: The EPA agrees with the commenter and revised the reporting requirements in

§60.1900 to indicate that COMS readings that are above the opacity standard are not violations. 

Opacity limit violations can only be determined by Method 9 opacity tests and not by COMS data (see

Section 3.8.2 of 1995 BID).

4.5.2 Comments on Test Methods

Comment: Several commenters (IV-D-14, IV-D-05, IV-D-09, IV-G-06, IV-F-1g) requested

that EPA clarify the accuracy of the EPA test methods used to demonstrate compliance with the

emission limits. Some commenters (IV-D-14, IV-D-09, IV-F-1g) were concerned that uncertainty in

the test methods could lead to a higher risk of noncompliance for facilities, especially if states adopt

more stringent standards than the emission guidelines. One commenter (IV-D-09) suggested that

uncertainty in the test methods, particularly that for dioxins/furans, could lead to a lack of enforcement

of the standards. 

One commenter (IV-D-05) asked the EPA to clarify whether the emission limits already

include a margin of error to account for “imperfection” (i.e., uncertainty) in the emission measurements

and variation in emissions. The commenter (IV-D-05) asked the EPA to clarify that States and

regulated facilities cannot add a margin of error to the emission limits to account for uncertainty in

emission measurements and variation in emissions.

Response: The test methods are adequate to use in application of the MWC regulations. The

development of the test methods is not part of this rulemaking. The adequacy of the test methods was

addressed in establishment of the test methods and was done in a separate rulemaking. The EPA

proposed and accepted comments on the test methods in separate rulemaking actions. Questions
61

submitted about the accuracy of the test methods, have been forwarded to the EPA emission

measurement laboratory for evaluation outside this rulemaking. 

The proposed emission limits already include a margin of error to account for uncertainty in the

emission measurements and normal variation in emissions. The proposed standards are clear that

compliance is based only on the average emissions measured during a compliance test. 

Comment: Three commenters (IV-G-06, IV-D-01, IV-F-1f) stated that the standards must

better address uncertainty in the emission measurement methods. One commenter (IV-G-06)

suggested a way to revise the equations in §60.1460 of the NSPS and §60.1935 of the emission

guidelines for determining percent reductions for Hg and HCl to better account for measurement

uncertainty. Two commenters (IV-D-01, IV-F-1f) also stated that the test methods for Pb, Cd, Hg and

dioxins/furans emissions have too much uncertainty and cannot be used for determining compliance with

the emission limits. One commenter (IV-F-1f) also stated that EPA must account for both process

variability and measurement uncertainty in setting emission limits. Finally, two commenters (IV-D-01,

IV-F-1f) stated that section 129(c) of the CAA requires that emission standards must be based on test

methods validated on solid waste combustion units.

Response: The EPA believes that all methods specified in the emission guidelines are valid for

use on MWC units. The docket contains several reports that deal with method validation studies

conducted on these methods on MWC units and similar sources. In addition, the emissions data on

which the standards are based are the same measurement methods that will be used to determine

compliance. Process variations and emission variations result in emission data variation and all emission

measurement methods have some uncertainty. The proposed emission limits account for all of these

factors (process variation, emission variation, and measurement uncertainty). Additionally, these test

methods and calculation procedures are the same as those included in the 1995 standards (see

Section 3.8.3 of 1995 BID).

Comment: Two commenters (IV-G-06, IV-F-1f) noted that the likelihood of a violation

increases as the number of limits in the standard increases and as the number of units at a plant

increases. The commenters were concerned that the emission limits are based on individual

achievement of the limits and not simultaneous achievement of all the limits. The commenters suggested

that the language of §60.1705 of the emission guidelines be revised so that small exceedances of the

limits are not considered violations if subsequent testing indicates compliance or if the exceedance is
62

within the measurement uncertainty of the test methods. One commenter also asked EPA to solicit

comments on determining measurement uncertainty using EPA Method 301 and at the proposed

regulatory limits, and on demonstrating compliance with multiple emission limits.

Response: The proposed limits include a consideration for measurement uncertainty and

process variability and are simultaneously achievable. Allowances for small exceedances, as suggested

by the commenters, are not needed. The EPA has already accepted comments on the test methods

and the achievability of the emission limits. The EPA sees no need to solicit additional comments. In

addition, because MACT must be achievable and there is inherent variation in emissions over time and

among MWC units, even when the MWC units and control devices are well designed, operated, and

maintained, the floor emission levels are set at the levels that are demonstrated to be achievable by the

population of MWC units with the best technology.

Comment: One commenter (IV-D-07) asked EPA to clarify the compliance testing schedule. 

The commenter (IV-D-07) stated that §60.1795(b) appears to require dioxin testing on an annual basis

whereas §60.1795(a) states that stack testing can occur each 36 months if all stack tests for a given

pollutant show emission levels that are less than the limit for the unit in question. The commenter

(IV-D-07) supports stack testing at a reasonable frequency and considers annual stack testing, without

some relief provision recognizing proper operation or superior performance, is unreasonable. The

commenter (IV-D-07) supports the proposed frequency for stack testing if §60.1795(a) applies to all

of the tests required under §60.1785, including dioxins/furans testing.

Response: All Class I and II units must do stack tests for dioxins/furans annually (§60.1775);

however, the regulation does allow for reduced testing for Class I and II units (§60.1795). For Class I,

reduced testing of dioxins/furans is allowed for MWC units that have demonstrated levels of

dioxins/furans less than or equal to 15 nanograms per dry standard cubic meter for 2 consecutive years

(§60.1795(b)) . For Class II units, two reduced testing options are available. (1) Similar to the

reduced testing described above, reduced testing of dioxins/furans is allowed for MWC units that have

demonstrated levels of dioxins/furans less than or equal to 30 nanograms per dry standard cubic meter

for 2 consecutive years. (2) Reduced testing of all pollutants is allowed for Class II MWC units that

have demonstrated compliance with all pollutants, including dioxins/furans, over 3 consecutive years

(§60.1795(a)). These sections of the emission guidelines have been edited to make these provisions

more clear.
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Comment: One commenter (IV-F-1f) stated that the annual retest language (§60.1785 of

emission guidelines and §60.1295 of NSPS) should be changed to require annual retesting, either within

13 months or within 54 weeks. The commenter (IV-F-1f) pointed out that the current retest language

can create a rollback or ratchet effect, where you actually have less than twelve months to retest. The

commenter (IV-F-1f) stated that the language could be interpreted as meaning within 12 months from

the day the last test was finished, not 12 months from the month it was finished.

Response: The EPA agrees with the commenter that the current requirement to test within 12

months of the last test could imply that annual stack tests must be no later than 12 months apart. 

Because it may be difficult to schedule tests exactly 12 months apart, the testing schedule would be

compressed so it was more frequent than annual testing. The emission guidelines (§60.1785 and

§60.1795) have been revised to require annual stack tests to be no later than 13 months apart to allow

some flexibility in the annual scheduling tests.

Comment: Three commenters (IV-G-01, IV-G-07, IV-F-1f) requested that EPA require only

a 3-hour minimum sampling time for dioxin and furan test runs. The commenters (IV-G-01, IV-G-07,

IV-F-1f) believe a 4-hour minimum sampling time will not add significantly to the accuracy of the test

results and will add extra costs for testing and impose an additional burden on the stack test team. The

commenters (IV-G-01, IV-G-07) stated that the extra sampling hours easily add an additional day to a

dioxins/furans stack test. One commenter (IV-G-01) noted that 3 runs of 4 hours each takes well over

12 hours to complete without errors. Another commenter (IV-G-07) stated that adding an additional

day to a dioxins/ furans stack test could skew the test results and create another potential for error to

the test. The third commenter (IV-F-1f) stated that the 4-hour sampling time does not reflect the latest

analytical technology.

Response: The EPA is keeping the requirement for a 4-hour sampling time for the

dioxins/furans test method in the emission guidelines. However, facility operators have the option of

applying to the Administrator for approval to use a shorter sampling time on a case-by-case basis,

under the general provisions (40 CFR part 60, Subpart A). The test method section of the emission

guidelines has been revised to clarify that facility operators may apply to the Administrator for approval

of alternative or equivalent test methods or modifications of the final test methods.

Comment: One commenter (IV-G-06) recommended modifying §60.1935(a) of the MWC

rule to eliminate the problem of public misperception of adverse environmental consequences
64

associated with inappropriately inflated emitted concentrations during startup and shutdown due to the

mathematical effects of the oxygen correction factor. See the general provisions for requirements

during such periods.

Response: The EPA sees no need to modify the oxygen correction factor for startup and

shutdown periods. The emission guidelines do not regulate emissions during these periods and do not

require recording or reporting emissions during these events. 

Comment: One commenter (IV-F-1f) presented an alternative dry sorbent injection test

procedure that uses Method 19 to determine removal efficiency along with CEMS. The commenter

(IV-F-1f) stated that the proposed rule has some undefined terms that are defined in Method 19. The

commenter’s (IV-F-1f) method gives two baselines and a control, which allows you to determine

control efficiency as you measure the concentration when the sorbent is injected versus when it is not

injected, and make an uncertainty correction based on the dual train results. The commenter (IV-F-1f)

stated that the unit should be considered in compliance if both data sets meet the standard.

Response: The EPA is not modifying the current test procedures for determining removal

efficiency for HCl and SO2. However, owners and operators have the option of applying to the

Administrator for approval to use alternative test methods on a case-by-case basis, under the general

provisions (40 CFR part 60 Subpart A). The final rule clarifies that this flexibility exists.

Comment: Four commenters (IV-G-04, IV-G-06, IV-D-27, IV-F-1f) stated that it is

impossible to measure and monitor acid gas (SO2 and HCl) emissions at the inlets to certain acid gas

control systems, such as dry sorbent injection systems or furnace sorbent injection systems. Therefore,

they must turn off the sorbent injection system to measure uncontrolled emissions for use in determining

acid gas removal efficiency. One commenter (IV-G-04) also noted that this problem exists for

determining Hg emission reduction efficiency. In some cases, the sorbent injection system must be

turned off for up to 12 hours before the test and during this time the facility cannot comply with the acid

gas emission limits. Two of the commenters (IV-G-04, IV-G-06) also noted that they cannot install an

SO2 monitor at the control device inlet in these situations to continuously monitor SO2 reduction

efficiency. The commenters (IV-G-04, IV-G-06, IV-D-27, IV-F-1f) proposed amending the

monitoring requirements at §60.1720(e) and the emission reduction efficiency equations at §60.1935 to

allow facility operators to use a parametric method to measure and monitor acid gas or Hg reduction

efficiency. 
65

Three of the commenters (IV-G-06, IV-D-27, IV-F-1f) also asked EPA to allow a waiver of

the acid gas emission limits during testing so facility operators turn off the acid gas control system and

collect the uncontrolled data needed to determine reduction efficiency. The commenters noted that the

hazardous waste combustion NESHAP (40 CFR part 60, Subpart EEE) contains a waiver of emission

reduction efficiency and concentration limits during compliance testing and model calibration.

Response: Facility owners and operators can comply with either the HCl and SO2 reduction

requirements or the HCl and SO2 concentration limits. If they must turn off the acid gas control system

(e.g., the dry sorbent injection system) to measure HCl or SO2 removal efficiency, the operator can

complete testing before the compliance date for their facility without violating the emission standards. 

After the compliance date, facility operators can use a parametric method for determining removal

efficiency. The docket for the large MWC rulemaking contains a paper (Docket No. A-89-09, IV-B22) describing this procedure. Facility operators already have the option of applying to the

Administrator for approval to use parametric monitoring or alternative test methods on a case-by-case

basis, under the general provisions (40 CFR part 60, Subpart A). These alternative methods can

include the changes to the equations in §60.1920 suggested by the commenters. The final emission

guidelines clarify that this flexibility exists. 

Comment: One commenter (IV-D-05) requested that EPA make it clear that for a garbage

incinerator there is not a normal distribution in emissions because the waste stream varies. The

commenter (IV-D-05) noted that measurements made on different days cannot really be compared and

assumed to represent a normal distribution. The commenter (IV-D-05) questioned if sampling using

multiple nozzles within a couple of inches of one another could eliminate the variations caused by the

waste stream. The commenter (IV-D-05) noted that air is more likely to flow up the stack in some sort

of spiral so even simultaneous sampling with multiple nozzles does not measure the same actual

emissions.

Response: The emission limits, sampling, measurement, and monitoring methods and

requirements in the proposed rule address the commenter’s concerns about variability in emissions,

including variability over time in the waste stream and cyclonic gas flow in the stack. 

Comment: One commenter (IV-G-10) requested that both Method 26 and 26A be allowed

for hydrogen chloride testing. The commenter (IV-G-10) conducts hydrogen chloride testing using

Method 26A in a non-isokinetic mode (single-point constant rate sampling). According to the
66

commenter (IV-G-10), Method 26A eliminates the problems caused by the heated glass stopcock and

makes it much easier to maintain temperature to prevent water condensation and hydrogen chloride

scrubbing. In addition, the commenter (IV-G-10) noted that Method 26A can also be combined with

Method 5 to reduce testing costs.

Response: The EPA revised Table 8 of subpart BBBB to add Method 26A as an alternative

test method to Method 26. 

Comment: One commenter (IV-D-15) recommended that if EPA cannot require continuous

monitoring for pollutants such as dioxins/furans, then EPA should require more frequent testing. The

commenter (IV-D-15) stated that the process of relying on annual stack test data is full of holes,

particularly the uncertainty of knowing the emission rates on the other 362 or so days of the year. The

commenter (IV-D-15) also believes that if there were more frequent stack tests, then enforcement

issues would not drag on for longer than necessary.

Response: The requirements for annual testing and continuous emissions or parametric

monitoring are the same as those in the 1995 rules for small MWC units, which are reinstated by the

proposed rules. The technology and requirements are appropriate for ensuring continuous compliance

with the emission standards. The States can require more frequent testing if they see fit to do so.

Comment: Two commenters (IV-D-15, IV-D-10) recommended that EPA require stack

testing at different times of the year, not just testing on an annual basis. One commenter (IV-D-15)

stated that if EPA required testing during the winter when yard waste and green waste is minimal, then

EPA would probably catch the source at its worst emission levels of the year. The commenter

(IV-D-15) believes that to assume emissions in January (when there is minimal green waste) are

comparable to emissions in September is wrong, irrational, and not supported by adequate logic and

facts. The second commenter (IV-D-10) recommended requiring testing each calendar year, but

occurring at least every 15 months. The commenter (IV-D-10) stated that this requirement would

allow flexibility to the small municipal waste combustor for seasonal rotation and other scheduling

aspects. 

Response: Stack testing must be conducted by 180 days after the compliance date. Therefore,

the stack test date could occur at any time of year. The EPA is not modifying the testing or monitoring

schedule; however, States may require more frequent testing if they see fit to do so.
67

Comment: One commenter (IV-G-04) agrees with the rationale of crediting a facility for a

good track record of compliance monitoring and believes that such credit is appropriate regardless of

the subcategory in which the facility falls. This commenter (IV-G-04) recommended that EPA amend

§60.1795 by adding a condition (c) similar to condition (a) that would provide some additional relief

from the financial burden of stack testing to owners and operators of municipal waste combustor plants. 

Response: The testing schedule in the proposed standards is the same as that contained in the

1995 regulations for small MWC plants, which are reinstated by today’s action. The general provisions

(40 CFR part 60, Subpart A) allow facility operators to obtain approval for alternative or equivalent

testing schedules. It is not necessary to change the testing schedule as proposed by the commenter.

4.6 ENFORCEMENT, REPORTING, AND RECORDKEEPING PROVISIONS

4.6.1 Enforcement

Comment: Two commenters (IV-D-09, IV-D-05) advised EPA to make the small MWC 

regulations as clear and airtight as possible so that the regulations would be easier to enforce. One

commenter (IV-D-09) stated that EPA should provide all the necessary backup information so that

States do not have to fail to enforce the new regulations for lack of science. If EPA will provide the

evidence (and clarification on the accuracy of stack test methods, as well as other objections that

sources in various States have raised, the commenter (IV-D-05) believes it will maximize the chance

that these new regulations will actually be enforced.

Response: All of the data supporting these standards and the selection of test methods are

already contained in the public docket for this rulemaking and earlier rulemakings for MWC emission

standards. 

Comment: One commenter (IV-D-19) believes that there should be substantial penalties and

fines for violations. The commenter (IV-D-19) stated that without them, the rule will have no teeth and

no effect. The commenter (IV-D-19) also requested that EPA streamline the appeals process so that

sources do not tie up enforcement actions in endless appeals. 

Response: The subjects of fines, penalties, and the appeals process for violations are outside

the scope of this rulemaking. 

Comment: One commenter (IV-D-09) requested that EPA clarify what constitutes compliance

for the benefit of the public and for the benefit of State agencies in enforcing these regulations. One 
68

commenter (IV-D-05) believes that States need some clarification about the assumptions behind the

stack testing process in order to calculate days of compliance or noncompliance, and to calculate

penalties. 

Response: States have enforcement discretion based on stack test results and continuous

emissions and parameter monitoring data. That discretion is outside the scope of this rulemaking.

Comment: One commenter (IV-D-05) believes that passing a stack test does not demonstrate

that a source was in compliance the rest of the year. The commenter (IV-D-05) believes that the

emissions on the day of the stack test are probably the best of any time during the year considering the

importance of passing the test, the ability to set up the test 45 days in advance, and the ability of the

source to control many of the operating parameters (including waste stream). 

Response: The EPA believes that the requirements for stack testing and continuous emissions

or parameter monitoring are sufficient to ensure continuous compliance. The monitoring provisions

ensure that air pollution controls and the combustion process are operated in the same way between

stack tests as they are during stack tests. 

Comment: One commenter (IV-D-05) requested clarification on the meaning of “for

2 consecutive years” in §60.1795. Paragraph (b) allows an owner or operator to test less frequently if

the MWC unit(s) has demonstrated emission levels less than the respective limit for 2 consecutive

years. The commenter (IV-D-05) questioned if it means there was a stack test that tested in

compliance during 2 consecutive years.

Response: The phrase referred to by the commenter (“two consecutive years”) means two

consecutive annual compliance tests. The facility operator must still comply with the continuous

monitoring requirements during the period when they are allowed to skip the annual compliance tests.

Comment: One commenter (IV-D-05) asked if there is a proven relationship between inlet

temperature at the air pollution control device and dioxin emissions for various types of municipal waste

combustors. The commenter (IV-D-05) also asked if a historical relationship between inlet

temperature and dioxin emissions is a reason to disregard a stack test report that indicates a source was

in violation. The commenter (IV-D-05) requested that EPA provide the States with guidance on the

relationship between inlet temperature and dioxin emissions. 
69

Response: A relationship exists between air pollution control device inlet temperature and

dioxins/furans emissions, but it is not strong enough to waive the requirement for an annual compliance

test or to disregard a stack test that indicates a violation of the emission standard.

Comment: One commenter (IV-G-06) recommended the EPA modify the sentence in

§60.1615 of the emission guidelines that reads: “You must submit a signed copy of the contract to

initiate onsite construction...” to read: “You must submit a signed copy of the contract, but not the

documents incorporated by reference or any attachments, to initiate onsite construction...” The

commenter (IV-G-06) states that turnkey contracts, the way most of these modifications will be made,

include a complete copy of the procurement specifications and contractor’s proposal, and this

information may be proprietary in nature and provides the EPA no useful purpose.

Response: The commenter’s suggestion seems to be a reasonable way to protect proprietary

information and reduce the paperwork submitted to EPA. The EPA made the suggested change to the

emission guidelines. 

4.6.2 Recordkeeping and Requirements

Comment: One commenter (IV-D-13) was unable to find the section of 40 CFR part 60,

Subpart A related to submission of the initial report as required in §60.1870 of the emission guidelines. 

The commenter (IV-D-13) requested that the section provide a full reference.

Response: The EPA agrees with the commenter and added the exact citation for the section of

the general provisions to the language in the emission guidelines. The initial semi-annual compliance

report must be post-marked no later than 30 calendar days after the end of the first 6 month reporting

period, as specified in §60.7(c).

4.7 LEGAL CONSIDERATIONS

Comment: One commenter (IV-D-23) stated that EPA’s failure to include standards for

MWC with capacities of less than 35 megagrams per day would be unlawful. The commenter

(IV-D-23) cited the CAA, which requires EPA to promulgate emission standards for all units

combusting municipal waste (42 U.S.C. 7429(a)(1)). The commenter (IV-D-23) stated that there is

no basis for EPA’s decision not to include standards for units with capacities of less than 35 Mg per
70

day (64 FR 47236) in this rulemaking. The commenter (IV-D-23) states that, accordingly, the

regulations for small MWC will violate the CAA if they do not include standards for such units. 

Response: The EPA is reestablishing the 1995 regulations for small MWC units. Those

regulations included a lower size cutoff. This does not mean that EPA will not develop regulations for

units smaller than 35 tons per day. The EPA considers MWC units smaller than 35 tons per day to be

a separate subcategory of small MWC units. Section 129(a)(2) of the CAA specifically authorizes

EPA to distinguish among sizes of units within a category in establishing standards. The EPA is not

addressing requirements for MWC units smaller than 35 tons per day in this rulemaking.

Comment: One commenter (IV-D-23) stated that EPA’s failure to establish numerical emission

limits for NOX for the proposed Class C MWC units violates the CAA. The commenter (IV-D-23)

cited Section 129(a)(4) of the CAA that says performance standards applicable to solid waste

incineration units “shall specify numerical emission limitations for the following substances or mixtures:

particulate matter (total and fine), opacity (as appropriate), sulfur dioxide, hydrogen chloride, oxides of

nitrogen, carbon monoxide, lead, cadmium, mercury, and dioxins and dibenzofurans.” Because the

proposed rule does not specify numerical emission limitations for oxides of nitrogen for the proposed

Class B or Class C units, it would violate the CAA. The commenter (IV-D-23) noted that EPA did

not explain why the proposed standards do not specify numerical emission limitations for NOX, but

merely cited the preamble to the 1995 regulations (59 FR 48228). The commenter (IV-D-23) stated

that EPA’s failure to comply with the CAA in promulgating standards for large MWC units does not

excuse its failure to comply with the CAA in promulgating standards for small MWC units. The

commenter (IV-D-23) stated that the CAA requires the EPA to promulgate these standards and no

EPA explanation can alter this requirement. 

Response: The commenter correctly points out that Section 129 of the CAA requires NOX

limits. This means that emission limits for these pollutants must be specified even if the MACT selected

for a subcategory of facilities does not control that particular pollutant. The MACT floor and MACT

for Class C (renamed Class II) units is “no control.” None of the Class II units has NOX controls, and

the technical feasibility and performance of selective non-catalytic reduction (SNCR) controls for

existing Class II modular starved air combustors is uncertain as described in the 1994 preamble. 

Therefore, in the final rule, EPA has added a “no control” NOX emission limit of 500 ppmv for all Class
71

II units. The 500 ppmv emission limit is consistent with the “no control” NOX limit as proposed for the

emission guidelines on September 20, 1994 (59 FR 48255).

This final limit is not intended to result in NOX emissions control, and the final emission

guidelines for Class II MWC units do not include any associated monitoring, testing, recordkeeping, or

reporting requirements. The 500 ppmv limit represents an emission level adequate to accommodate the

variability in NOX emission levels. Test data in the docket indicate that the 500 ppm level is achievable

for all combustor types.

Comment: One commenter (IV-D-23) stated that the omission of CO limits (and an

explanation) constitute a violation of the CAA. The commenter (IV-D-23) noted that the proposed

rule does not specify numerical emission standards for CO, except for a limited subcategory of fluidized

bed combustion units the co-fire wood and RDF. The commenter stated that the failure to specify

numerical CO emission limits constitutes a missed opportunity to reduce dioxins/furans emissions since

CO levels are indicative of good combustion and good combustion reduces dioxins/furans levels. 

Response: The commenter is mistaken and has missed part of the regulations. Table 2 of

Subpart AAAA (64 FR 47304) and Table 5 of Subpart BBBB (64 FR 47271) list the proposed CO

emission limits for new and existing small MWC units, respectively. All small MWC units are subject to

CO limits in the proposed and final regulations. The CO limits are listed in Table 5 of subpart BBBB.

Comment: One commenter (IV-D-23) stated that EPA’s failure to establish numerical emission

limits for polychlorinated biphenyls (PCBs) violates the CAA. The commenter (IV-D-23) cited

Section 112(c)(6) of the CAA, which requires EPA to assure that source categories accounting for

90 percent of all PCB emissions are subject to MACT standards “with respect to” PCBs. The

commenter (IV-D-23) cited EPA as stating that MWC units account for more than half of the

aggregate emissions of PCBs (63 FR 17838 and 17849, April 10, 1998). The commenter (IV-D-23)

argues that EPA cannot possibly meet the requirements of Section 112(c)(6) without subjecting MWC

units, including the small MWC subcategory, to MACT standards for PCBs. The commenter also

pointed out that EPA has acknowledged in its final Great Waters determination under

Section 112(m)(6) of the CAA, that “Section 112(c)(6) requires that EPA identify and list for

regulation sources to assure that at least 90 percent of the aggregate emissions of each of seven

pollutants are subject to Section 112(d) standards” (63 FR 14090, March 24, 1998). The commenter
72

(IV-D-23) stated that therefore, the small MWC regulations will violate the CAA if they do not include

PCB standards.

Response: The commenter cited Section 112(c)(6) of the CAA. However, the small MWC

regulations were developed under Section 129 of the CAA. Section 129 does not require regulation of

PCB from small MWC. The EPA does not believe that Congress intended that the solid waste

incineration units required to be regulated under section 129 of the CAA be subject to section

112(c)(6) of the CAA. Section 129(a)(4) of the CAA requires EPA to establish numerical emission

limitations for a specified list of pollutants. Had Congress intended to require that PCB emissions from

solid waste incineration units be specifically controlled, EPA believes Congress would have included

PCB in the list of pollutants for which numerical emission limitations are required. Congress did not do

so. The control technologies used to comply with the small MWC regulations will, nevertheless, result

in reductions in PCB. Adding specific emission limits for PCB is not required and would not result in

further reduction in PCB emissions from small MWC. PCB emission limits are, therefore, not included

in the final regulations.

Comment: One commenter (IV-D-23) stated that EPA’s failure to establish final emission

standards that reflect the reductions achievable through pollution prevention measures would violate the

CAA. The commenter (IV-D-23) cited Section 129(a)(2) and (a)(3) of the CAA and believes that

these requirements must be read together and that if any measure, including a pre-combustion measure,

is necessary to obtain the maximum reduction that is achievable, EPA must require it. The commenter

(IV-D-23) believes that failing to evaluate the effectiveness and achievability of measures identified by

EPA or advocated by commenters is arbitrary and capricious (AT&T corp. V. FCC, 86 F.2d 242,

247 (D.C. Cir. 1996)).

The commenter (IV-D-23) advocates eliminating or reducing metals and chlorinated plastics in

the waste stream at small MWC facilities. The commenter (IV-D-23) believes that this is an achievable

beyond-the-floor measure that would reduce metals emissions beyond the floor requirements, and

reduction of chlorinated plastics would reduce dioxin and hydrogen chloride emissions. The commenter

(IV-D-23) states that it feasible both technically and economically for MWC owners or operators to

separate metals or require their customers to do so. The commenter (IV-D-23) states that feed limits

are particularly appropriate for mercury, lead, and cadmium, which are known to be significant adverse

“non-air quality health and environmental impacts.” Another commenter (IV-D-07) recommended that
73

EPA take a lead role in pollution prevention through product formulation controls, which is an initiative

that is fundamental to the protection of our soil, air, and water. The commenter (IV-D-07) believes

that it would be most prudent to control toxic metals at the source where control is highly efficient and

cost effective. The commenter (IV-D-07) stated that there has been no comprehensive national effort

to control toxic metals at the true source, the mines and markets that produce and distribute them.

Response: Commenter IV-D-23 raised the same issue in its litigation of the regulations for

Hospital/Medical/Infectious Waste Incinerators (HMIWI). In the Sierra Club decision (Sierra Club V.

EPA, 167 F.3d 658, 663 (D.C. Cir. 1999)) for the HMIWI rule, the court rejected the commenter’s

claim. In that litigation, the court said that “[i]n the absence of any type of quantification of benefits or

costs, the Administrator had no basis for finding that, ‘taking into account the cost,’ emissions

reductions from pollution prevention programs were ‘achievable’ as the statute uses the word.” As in

the HMIWI rule, EPA does not have evidence that allows quantification of the relevant reduction

achievable through pollution prevention measures (e.g., including control of consumer products). 

However, EPA has included the following pollution prevention measures in the regulations. New

MWC units subject to the NSPS must prepare a materials separation plan, which identifies a goal and

an approach for separating certain components of municipal solid waste prior to combustion and

making them available for recycling. In addition, new and existing small MWC units must maintain a

specified load level and maintain a specified temperature at the inlet of the PM control device. These

operating requirements help assure good combustion, which prevents pollution (see Section 3.10 of

1995 BID).

Comment: Two commenters (IV-D-23, IV-G-06) stated that EPA’s failure to consider nonair quality health and environmental impacts in setting final emission standards would violate the CAA. 

The commenter (IV-D-23) cited Section 129(a)(2) of the CAA, which requires EPA to set standards

that “reflect the maximum degree of reduction in emissions of air pollutants... that the Administrator,

taking into consideration the cost of achieving such emission reduction, and any non-air quality health

and environmental impacts and energy requirements, determines is achievable...” The commenter

(IV-D-23) stated that although EPA stated that it considered non-air quality health and environmental

impacts in setting final emission standards (64 FR 47237), there is no evidence that it did so for the

proposed Class A and Class B small MWC units. The commenter (IV-D-23) believes that, for both
74

Class A and B MWC units, EPA neither discussed nor considered non-air quality health and

environmental impacts in establishing more stringent emission standards based on these impacts.

Response: Commenter IV-D-23 raised the same issue in its litigation of the regulations for

Hospital/Medical/Infectious Waste Incinerators (HMIWI). In the Sierra Club decision (Sierra Club v.

EPA, 167 F.3d 658, 663 (D.C. Cir. 1999)) for the HMIWI rule, the court rejected the commenter’s

claim, finding that they had failed to demonstrate that the factors they present are “non-air quality health

and environmental impacts” within the meaning of Section 129. The commenter has provided no

additional information in support of their claim. EPA has fully considered what it deems to be the

potential non-air quality health and environmental impacts resulting from implementation of the

regulations. For example, EPA evaluated the increase in solid waste and wastewater resulting from

implementation of the regulations. 

Comment: One commenter (IV-D-23) stated that EPA’s failure to comply with the MACT

floor requirements of Section 129 of the CAA would violate the CAA. Three commenters (IV-D-23,

IV-D-16, IV-D-26) cited a court decision (Sierra Club v. EPA, 167 F.3d 658, 663 (D.C. Cir. 1999))

(Sierra Club), which requires EPA to set floors that reflect the actual performance of the best

performing units. Commenters (IV-D-23, IV-D-16) noted that under the Sierra Club decision, EPA

may only use permit and regulatory data to establish floors if those data allow a reasonable inference as

to the performance of the top 12 percent of units. Additionally, the commenters (IV-D-23, IV-D-16,

IV-D-26) noted that EPA may only use uncontrolled data if there is a reasonable basis for believing

that some of the best performing 12 percent of units are uncontrolled and if the specific uncontrolled

data that EPA uses give a reasonable representation of the performance of those units in its averaging. 

One commenter (IV-D-23) stated that EPA has attempted to base the small MWC MACT

floors on permit and regulatory data, but failed to prove that those data reflect the actual performance

of the best units. The commenter (IV-D-23) contends that none of the supporting documentation

demonstrates that the permit and regulatory data reflect the actual performance of the best units. 

Therefore, the commenter (IV-D-23) stated that EPA’s use of regulatory and permit data to set floors

for the small MWC category is arbitrary, capricious, and unlawful. In addition, commenters (IV-D-23,

IV-D-16, IV-D-26) believe that it is not reasonable to use uncontrolled emission values in the MACT

floor calculation because the commenters believe that some of the best performing 12 percent of units

employ controls.
75

One commenter (IV-D-23) stated that it is irrational to attempt to fill the data gaps with

“uncontrolled default emission values” data that do not even purport to represent the actual

performance of the best performing 12 percent of units. The commenter (IV-D-23) contends that EPA

has not provided any basis to believe that Class A units that are not subject to permit or regulatory

limits for dioxin do not employ any emissions controls that reduce their dioxin emissions. The

commenter (IV-D-23) states that the data that EPA provides indicate that at least two Class A units do

employ some emissions controls to meet other permit requirements (indicating that Class A units are

subject to permit requirements for other pollutants). Therefore, the commenter (IV-D-23) claimed that

EPA’s assumption that the best performing units emit uncontrolled levels of dioxin is unfounded.

Two other commenters (IV-D-16, IV-D-26) believe that some of the best performing

12 percent of units are controlled. Based on the Sierra Club court decision, two commenters

(IV-D-16, IV-D-26) believe that the use of uncontrolled data in the HCl floor calculation for Class B

MWC units is not reasonable because, based on the 1994 proposal preamble (59 FR 48228) and

background documents, it is implied that 12 percent of the polled number of units do control for HCl

with DSI. One commenter (IV-D-16) noted that the Cd, Pb, and Hg standards are more stringent than

the floor and have been demonstrated to be achievable by DSI/ESP. The commenter (IV-D-16)

suggested that EPA should also base the HCl standard on DSI/ESP because this control system is

already the basis for Class B Cd, Pb, and Hg standards. The commenter (IV-D-16) believes that

unless EPA can demonstrate that 12 percent of the Class B population does not have HCl controls and

that data are not available to characterize HCl emissions from DSI/ESP, it is not appropriate to use the

current floor for the HCl emission standard. In addition, the commenter (IV-D-16) believes that EPA

should provide specific justification for the use of uncontrolled data in the calculation of floors that are

used as a basis for emission standards for Class A, B and C MWC units.

Response: The EPA used a permit approach to determine the MACT floors in the 1995

emission guidelines (40 CFR part 60, Subpart Cb) and believes that using the permit approach is

appropriate for this rulemaking. Permit limits and regulatory limits provide a reasonable estimate of the

actual performance of the best performing units under the worst reasonably foreseeable circumstances,

making this approach consistent with the court opinion in the Sierra Club case. Permit limits include a

margin for compliance and must be achievable. In circumstances where permit limits were higher than

EPA's uncontrolled emission factor, the uncontrolled emission factor was used in the MACT floor
76

calculation rather than the actual permit limit. To demonstrate that EPA’s approach on small MWC is

valid, EPA calculated the MACT floors for small MWC using a technology-based approach which is

described in a technical memorandum entitled “Determination of Maximum Achievable Control

Technology (MACT) (Technology basis)” that is in the docket. The resulting MACT floors reflect the

same technology as would be needed to meet the proposed and final MACT floors. Consequently,

EPA has not modified the MACT floor calculation procedure for this source category. The purpose of

this regulatory action is to reestablish the regulations that were vacated in 1995. The EPA is using the

same procedure used in the 1995 regulations to calculate the MACT floors. 

Comment: One commenter (IV-G-06) believes that the correct inventory for the EPA to use to

establish the number of units to be included in the MACT inventory is the one that existed no later than

November 15, 1992. In a separate statement, this same commenter (IV-F-1f) stated that EPA

appropriately stopped data acquisition on the time lines that are imbedded in the law and appropriately

used the information available to establish the emission limitations. In addition, the commenter

(IV-F-1f) agreed that EPA appropriately used the current (1998) inventory to determine the benefits,

costs, and cost effectiveness of the rule. Another commenter (IV-D-18) suggested that EPA use an

inventory more current than the 1995 inventory. The commenter (IV-D-18) believes that the number

of units in the category has changed significantly since the 1995 final emission guidelines, and therefore,

the emission limitations no longer reflect “the average emission limitations achieved by the best

performing 12 percent of units in the category” because the inventory has changed significantly since

1995. 

Response: The EPA agrees that different cutoff dates could have been used to calculate the

MACT floors for existing small MWC units. The purpose of this rulemaking is to reestablish emission

guidelines for small MWC units. Therefore, for this rulemaking, the EPA believes that it is appropriate

to use the same inventory it used to develop the 1995 emission guidelines (40 CFR part 60,

Subpart Cb) with the following minor changes consistent with the court’s opinion in the Davis County

litigation (Davis County Solid Waste Management and Recovery District v. EPA, 108 F. 3d 1454,

D.C. Cir. 1997). Before calculating the MACT floors for the proposed and final classes of existing

small MWC units, EPA removed large MWC units (MWC units greater than 250 tons per day),

consistent with the court’s opinion. In addition, the EPA revised the lower size cutoff for the
77

subcategory of small MWC units not being addressed in this rulemaking from 40 tpd on an aggregate

plant capacity basis to 35 tpd on an individual unit capacity basis (see Docket No. A-98-18). 

Comment: One commenter (IV-D-23) stated that EPA’s failure to make emissions data for the

proposed Class A, B and C units available is unlawful. The commenter (IV-D-23) cited Section 307

of the CAA, which requires the EPA, no later than the date of proposal, to include in the docket (A)

factual data on which the proposed rule is based, and (B) the methodology used in obtaining the data

and in analyzing the data. The commenter (IV-D-23) stated that EPA based some MACT floors on

“uncontrolled default emission values” that were based on emissions test data and AP-42 emission

factors. The commenter (IV-D-23) also stated that, in basing the MACT floor on AP-42 emission

factors and test data, EPA did not do any of the following: (1) provide the test data it used; (2) show

how that test data reflect the performance of any small MWC units; (3) show how it combined the test

data with AP-42 emission factors for any given pollutant; or, (4) why that combination reflects the

actual performance of units not subject to permit and regulatory limits. 

One commenter (IV-D-05) requested that EPA explain the uncontrolled default emission value

based on AP-42 and how it was determined. One commenter (IV-D-23) claimed that EPA has

violated Section 307 of the CAA by not providing the test data, or the emission factors, or indicating

how it obtained and analyzed those data and emission factors. The commenter (IV-D-23) stated that

because EPA has not made emissions data for the proposed Class A , B or C small MWC units

available, it is impossible for the public to determine what the actual floors (calculated in accordance

with Section 129 of the CAA) would be. The commenter (IV-D-23) stated that EPA must

immediately place in the docket all emissions test data, all emission factors, and an explanation of how

those emissions data and test factors were obtained and analyzed. The commenter (IV-D-23) also

stated that EPA must provide the public with the opportunity to comment on this information before

promulgating a final rule.

Response: Detailed memoranda that show all of the data and assumptions used in calculating

the MACT floors are available in Docket A-98-18. These memoranda are easily identifiable by

searching the docket index. In addition, Docket No. A-98-18 incorporates by reference Docket

Nos. A-89-08 and A-90-45, which contain supporting information for the emission guidelines and

NSPS. All emissions data referenced in the memoranda and considered by EPA in developing the
78

emission guidelines and NSPS are included in these dockets. These data were in the docket(s) at the

time of proposal in August 1999.

Comment: Two commenters (IV-D-05, IV-D-09) requested that EPA set emission limits for

hydrogen fluorides and any other pollutants that EPA is authorized to regulate under the CAA. One

commenter (IV-D-09) claims that there are many more pollutants coming out of MWC units than are

covered in the proposed MWC regulations.

Response: The small MWC regulations were developed under Section 129 of the CAA. 

Section 129 does not require regulation of hydrogen fluorides from small MWC. However, the control

technologies used to comply with the small MWC regulations will result in reductions in hydrogen

fluorides. Adding specific emission limits for hydrogen fluorides would not result in further reduction in

hydrogen fluorides emissions from small MWC units and hydrogen fluorides emission limits are not

included in the final regulations.

4.8 COMPLIANCE SCHEDULES

Comment: One commenter (IV-D-04) recommended changing the emission guidelines to

make it clear that closure is always an option for compliance with the regulation. The commenter

(IV-D-04) provided a modification to the regulation. 

Response: The EPA revised §60.1535 of Subpart BBBB to make it clear that ceasing

operation is an option for compliance with Subpart BBBB. However, closure agreements are not

required for small MWC units. This is consistent with the 1995 rule requirements for small MWC units. 

If the owner or operator chooses to continue to operate (i.e., not close) a small MWC unit that does

not meet all of the requirements imposed by the State or Federal plan after the compliance date, then

that MWC unit will be considered out of compliance.

Comment: One commenter (IV-D-05) recommended that EPA accelerate the timetable for

enforcement of these regulations, especially for those units that could be relatively easily and

inexpensively retrofitted with a carbon injection system. The commenter (IV-D-05) believes that there

is no reason to give the MWC units 5 years to comply. The commenter (IV-D-05) believes that a

faster timetable for compliance and implementation would get the States to act more quickly. 

Response: Section 129 of the CAA allows up to 5 years after promulgation of these emission

guidelines to achieve final compliance and the EPA will continue to allow up to 5 years to achieve final
79

compliance (§60.1535(a)(1)). However, the State plan may include a compliance schedule of less than

5 years. The EPA agrees that owners or operators of some small MWC units could achieve final

compliance in less than 5 years, however, this is a site-specific consideration and may be addressed in

the State plan.
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81

5.0 MISCELLANEOUS COMMENTS ON MUNICIPAL 

WASTE COMBUSTOR EMISSIONS GUIDELINES

5.1 DETERMINING MWC UNIT CAPACITY

Comment: One commenter (IV-D-10) suggested that the exact formula for determining the

capacity of a MWC unit be included in the rule (§60.1935). The commenter (IV-D-10) provided a

new paragraph (d) for §60.1935 that requires the reference of ASME PTC 33. The commenter

(IV-D-10) also suggested that the rule offer owners or operators the option of submitting alternative

efficiency determinations to the Administrator that are based on ASME performance test codes. 

Response: The EPA agrees that determining the capacity of an MWC unit could be done in

different ways. However, the EPA is not revising the regulation to include the commenter’s suggestion. 

The purpose of this rulemaking is to reestablish emission guidelines for small MWC units and EPA is

promulgating the emission guidelines as proposed.

5.2 STATE PLANS

Comment: One commenter (IV-D-13) requested that EPA make it clear that States are

allowed to deviate from the language used in the model rule (as provided in §60.1575).

Response: As stated in §60.1570, States are allowed to deviate from the language used in the

model rule as long as the State demonstrates that the alternative language is as protective as the model

rule. 

Comment: One commenter (IV-G-03) recommended that States be given a reasonable

amount of time to submit plans under Section 129 of the CAA to implement emission guidelines after

publication of the final rule. The commenter (IV-G-03) believes that a minimum of 24 months is

necessary in order to meet with interested parties and to complete the State’s regulatory process. 

Response: The EPA is not revising §60.1505(b) of Subpart BBBB because the emission

guidelines are developed in accordance with Section 129 of the CAA. Consistent with
82

Section 129(b)(2) of the CAA, the State must submit a State plan within 1 year of promulgation of the

emission guidelines. 

5.3 FEDERAL REGISTER PRINTING ERROR

Comment: Several commenters (IV-D-08, IV-D-25, IV-G-03) noticed that the emission

standards for acid gases and fugitive ash are missing from Table 2 of Subpart BBBB. 

Response: The emission limits for HCl, NOX, and SO2 were correctly printed in the preamble

to the proposed rule. However, because of a publication error, the emission limits for HCl, NOX, SO2,

and fugitive ash were omitted from Table 2 of Subpart BBBB. All emission limits are included in the

final rule. 

5.4 PUBLIC HEARING REQUIREMENT 

Comment: One commenter (IV-D-13) requested that EPA remove §62.1515(a)(6), which

requires a transcript of the public hearing as part of a State plan. The commenter (IV-D-13) states that

there is no rationale for this new requirement. The commenter (IV-D-13) cited 40 CFR 60.23(e) of

Subpart B, which requires the record of the public hearing to include a list of witnesses together with

the text of each presentation. The commenter (IV-D-13) also cited 40 CFR 60.23(f), which requires a

certification of the hearing, a list of witnesses and their organization affiliations, and a brief written

summary of each presentation or written submission. The commenter (IV-D-13) states that obtaining a

hearing transcript is expensive, labor-intensive, and no more informative than meeting the requirements

in 40 CFR 60.23(e) and (f).

Response: The EPA agrees that it may be more expensive to obtain a hearing transcript.

Therefore, EPA revised §60.1515(a)(6) to be consistent with the requirements of 40 CFR 60.23(f). 

The EPA notes, however, that 40 CFR 60.23(e) requires the State to prepare and maintain a record of

each hearing, including a list of witnesses and the text of each presentation.

Comment: One commenter (IV-D-13) requested that EPA make it clear in §60.1515(a)(9) of

Subpart BBBB, which requires the State plan to include a demonstration of the State’s legal authority

to carry out the Section 111(d) and Section 129 State plan, that the provisions of §60.25(d) of Subpart

B apply in this case. Subpart B requires each State plan to include legally enforceable procedures for
83

requiring owners and operators to provide information to the State for the purpose of determining

whether the facility is in compliance with the State plan.

Response: Consistent with 40 CFR 60.25(d) of Subpart B, §60.1515(a)(9) of Subpart BBBB

requires the State plan to include a demonstration of the State’s legal authority to carry out the

Section 111(d) and Section 129 State plan. No regulation change is necessary.

5.5 IMPLEMENTATION

Comment: One commenter (IV-D-13) is concerned that it appears with regard to this

proposed rule that EPA is significantly changing the role of EPA and the States in the implementation of

Section 111(d) programs, imposing additional administrative requirements, and thus discouraging

States from adopting the program.

Response: The State plans for small MWC units must be developed to satisfy the requirements

of both Section 111(d) and Section 129 of the CAA. Where conflicts arise, Section 129 takes

precedent. Under the CAA, the requirements of Section 129 are intended to be more restrictive than

the requirements of Section 111(d).

5.6 TITLE V PERMITS

Comment: One commenter (IV-G-03) recommended that EPA clarify when Title V permits

are required. The commenter (IV-G-03) notes that although Section 129 of the CAA requires MWC

units subject to either a NSPS or a State plan implementing an emission guideline to operate pursuant to

a Title V permit, neither the emission guidelines nor the NSPS indicates the schedule on which these

permits must be obtained. The commenter (IV-G-03) believes that it is inappropriate not to exempt an

MWC unit from the Title V requirements if the unit qualifies to be exempt from the State plan as

provide in §60.1555, even if its owner or operator fails to notify EPA that the unit qualifies to be

exempt from the State plan as provided in §60.1555. 

Response: Section 1555 of Subpart BBBB applies only to the emission guidelines (40 CFR

part 60, Subpart BBBB), does not address Title V requirements and has not been revised. Title V is

not addressed in this rulemaking because it is an independent EPA program outside the scope of this

rulemaking. 
84

5.7 DELEGATION

Comment: One commenter (IV-D-13) requested that Subpart BBBB be amended throughout

to substitute “State authority” for “Administrator.” The commenter (IV-D-13) is concerned that EPA is

asking the States to write a regulation that is chiefly administered by EPA with respect to discretionary

authority to the total exclusion of the States. The commenter (IV-D-13) believes that if the State

adopts a State regulation that gives the Administrator the authority as set forth in the model rule found in

Subpart BBBB, the State will not have the authority to make these decisions for Section 111(d)

sources unless EPA somehow transfers the authority back to the State. The commenter (IV-D-13)

also states that in this proposal, EPA makes it clear that a Section 111(d) program should be operated

similar to a delegated program. 

Response: The EPA believes the commenter misread the regulation. The definitions section of

Subpart BBBB (§60.1940) clearly states that the term “Administrator” used throughout the regulation

means the Administrator of the United States EPA or the Administrator of a State Air Pollution Control

Agency. In addition, State plans for small MWC units must be developed to satisfy the requirements of

both Section 111(d) and Section 129 of the CAA. Where conflicts arise, Section 129 takes

precedent. Under the CAA, the requirements of Section 129 are intended to be more restrictive than

the requirements of Section 111(d).
85

6.0 ADMINISTRATIVE REQUIREMENTS

6.1 EXECUTIVE ORDER 12866

Comment: One commenter (IV-D-21) believes that the obligation to determine the significance

of the regulatory action and submit it for OMB review is not discharged merely because EPA submitted

an earlier iteration of the rule for review - the obligation applies to each regulatory action. In addition,

the commenter (IV-D-21) believes that EPA erred in considering only the financial effect on the

economy in determining whether the proposed rule is “significant.” The commenter (IV-D-21) stated

that the proposed rule will have a dramatic and adverse effect on the ability of local governments to

effectively manage waste in their communities. 

Response: As stated in the preamble to the proposed rule (64 FR 47244), EPA conducted a

regulatory flexibility analysis for the emission guidelines and EPA concludes that the emission guidelines

will not have a significant economic impact on a substantial number of small entities, pursuant to the

provisions of 5 U.S.C. 605(b). The EPA recognizes that large expenditures will be required to retrofit

small MWC units to meet the emission guidelines; however, this impact is not considered to be a

“significant impact on a substantial number of small entities” according to the Regulatory Flexibility

Act/Small Business Regulatory Enforcement Fairness Act, and therefore, EPA is not required to submit

the rule to OMB for review. 
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TECHNICAL REPORT DATA

(please read instructions on the reverse before completing)

1. REPORT NO.

EPA-453/R-00-001

2. 3. RECIPIENT'S ACCESSION NO.

4. TITLE AND SUBTITLE

Small Municipal Waste Combustors: Background Information Document

for New Source Performance Standards and Emission Guidelines - Public

Comments and Responses.

5. REPORT DATE

June 2000

6. PERFORMING ORGANIZATION CODE

7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

U.S. Environmental Protection Agency

 Office of Air Quality Planning and Standards

Office of Air and Radiation

Research Triangle Park, North Carolina 27711

 10. PROGRAM ELEMENT NO.

11. CONTRACT/GRANT NO.

68-D6-0011

12. SPONSORING AGENCY NAME AND ADDRESS

Office of Air and Radiation

U.S. Environmental Protection Agency

Washington, DC 20460

13. TYPE OF REPORT AND PERIOD COVERED

Final Background Information

Document 

14. SPONSORING AGENCY CODE

EPA /200/04

15. SUPPLEMENTARY NOTES

16. ABSTRACT

This background information document contains summaries of the public comments that EPA received on the August

30, 1999 proposal to reestablish new source performance standards and emission guidelines for small municipal

waste combustion units. This document also contains EPA’s responses to those comments. This summary of

comments and responses serves as the basis for revisions made to the new source performance standards and

emission guidelines between proposal and promulgation.

17. KEY WORDS AND DOCUMENT ANALYSIS

a. DESCRIPTORS b. IDENTIFIERS/OPEN ENDED TERMS c. COSATI Field/Group

Air Pollution Control,

Small Municipal Waste 

Combustion Units

Air Pollution Control, 

Small Municipal Waste 

Combustion Units

18. DISTRIBUTION STATEMENT

Release Unlimited

19. SECURITY CLASS (This Report)

UNCLASSIFIED

21. NO. OF PAGES

90

20. SECURITY CLASS (This Page)

UNCLASSIFIED

22 PRICE