BACKGROUND PAPER
MUNICIPAL WASTE COMBUSTORS
AIR EMISSION STANDARDS
Office of Air Quality Planning and Standards
Environmental Protection Agency
April 26, 1989
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TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION 1-1
2.0 PROJECT BACKGROUND INFORMATION AND REGULATORY
OBJECTIVES 2-1
3.0 DESIGNATED POLLUTANT 3-1
4.0 MUNICIPAL WASTE COMBUSTOR PROFILE 4-1
4.1 TYPES OF COMBUSTOR DESIGN 4-1
4.2 MODEL PLANTS - SECTION 111(b) NSPS 4-2
4.3 MODEL PLANTS - SECTION 111(d) EMISSION
GUIDELINES 4-3
5.0 EMISSION CONTROL TECHNOLOGY AND PERFORMANCE 5-1
5.1 COMBUSTION CONTROL 5-1
5.2 PARTICULATE MATTER CONTROL 5-2
5.3 GOOD ACID GAS CONTROL (DRY SORBENT INJECTION/ESP) . 5-3
5.4 BEST ACID GAS CONTROL (SPRAY DRYER/FABRIC FILTER) . 5-4
5.5 MUNICIPAL SOLID WASTE MATERIALS SEPARATION 5-4
6.0 NEW MWC BASELINE, CONTROL OPTIONS, AND MODEL PLANT
ANALYSIS [Section 111(b) NSPS] 6-1
6.1 BASELINE AND CONTROL OPTIONS FOR NEW
MWC PLANTS 6-1
6.2 MODEL PLANT COST ANALYSIS 6-3
7.0 EXISTING MWC BASELINE, CONTROL OPTIONS, AND MODEL
PLANT ANALYSIS [Section 111(d) Emission Guidelines] ... 7-1
7.1 BASELINE AND CONTROL OPTIONS FOR EXISTING
MWC PLANTS 7-1
7.2 MODEL PLANT COST ANALYSIS 7-1
i i
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TABLE OF CONTENTS (CONTINUED)
Section Page
8.0 REGULATORY ALTERNATIVES 8-1
8.1 SUMMARY OF REGULATORY ALTERNATIVES 8-1
8.2 SMALL PLANT VERSUS LARGE PLANT DEFINITION 8-6
9.0 ECONOMIC AND ENVIRONMENTAL IMPACT ANALYSES FOR NEW MWC'S . 9-1
9.1 EMISSION AND AIR QUALITY IMPACTS 9.-1
9.2 COST IMPACTS OF REGULATORY ALTERNATIVES 9-4
9.3 PARTIAL BENEFITS ANALYSIS 9-8
9.4 ECONOMIC IMPACTS. . . 9-12
10.0 ECONOMIC AND ENVIRONMENTAL IMPACT ANALYSES FOR EXISTING
MWC'S . : 10-1
10.1 EMISSION AND AIR QUALITY IMPACTS 10-1
10.2 COST IMPACTS OF REGULATORY ALTERNATIVES 10-5
10.3 PARTIAL BENEFITS ANALYSIS 10-7
10.4 ECONOMIC IMPACTS 10-12
11.0 RCRA SUBTITLE D PROPOSED RULES 11-1
12.0 GLOSSARY OF KEY TERMS 12-1
13.0 REFERENCES 13-1
i i i
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TABLE OF CONTENTS (CONCLUDED)
Appendix
A MWC OPERATOR TRAINING AND CERTIFICATION
B SELECTION OF MONITORING REQUIREMENTS
C NITROGEN OXIDES
D HYDROGEN CHLORIDE AND SULFUR DIOXIDE EMISSIONS DATA
E TOXIC EQUIVALENCY CORRELATIONS AND TOTAL DIOXINS/FURANS
F MATERIALS SEPARATION
G ASH
H RISK
I REFERENCES
iv
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1.0 INTRODUCTION
The purpose of this document is to summarize key results of the various
regulatory analyses undertaken to support proposed regulations for new and
existing municipal waste combustors (MWC's) under Section 111 of the Clean
Air Act (CAA). This document does not address incineration of medical waste,
wastewater sludge, or hazardous waste.
The report is organized as follows: Section 2.0 presents information on
project background and regulatory objectives; Section 3.0 discusses
designated pollutants (MWC emissions) to be regulated under Sections 111(b)
and 111(d) of the CAA; Section 4.0 presents a profile of the MWC facilities
including both projected new MWC's subject to the 111(b) new source
performance standards (NSPS) and existing facilities subject to 111(d)
emission guidelines; Section 5.0 discusses emission control technology and
performance; Sections 6.0 and 7.0 present control options and model plant
cost analyses; Section 8.0 presents the regulatory alternatives investigated
for both new and existing MWC facilities; Sect-ions 9.0 and 10.0 discuss the
national economic and emissions impacts and benefits analyses. These
discussions include incremental impacts of the regulatory alternatives for
new and existing facilities; Section 11.0 describes impacts associated with
other municipal solid waste (MSW) related regulatory actions (i.e., the
proposed Subtitle D landfill regulations) for comparison with impacts of the
MWC regulations and guidelines; and Section 12 provides a glossary of some
key terms and acronyms.
Appendices A through I are attached as a separate volume to provide
information on related subjects of interest that do not appear in the text.
The appendices address the following topics: MWC operator training and
certification procedures; selection of emission monitoring requirements;
nitrogen oxide (N0X) emissions control; sulfur dioxide (SC^) and hydrogen
chloride (HC1) emissions variability; toxic equivalency of dioxins/furans;
materials separation and recycling issues; MWC ash disposal; and risk
assessment.
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2.0 PROJECT BACKGROUND INFORMATION AND REGULATORY OBJECTIVES
Air emissions from MWC's are currently regulated under two NSPS, one for
incinerators (40 CFR Part 60 Subpart E) and one for industrial-commercial -
institutional steam generating units (40 CFR Part 60 Subpart Db).a The
incinerator NSPS covers MWC units that coiranenced construction after 1971 and
limits particulate emissions from MWC's to less than 0.18 g/dscm (0.08 gr/dscf)
corrected to 12 percent carbon dioxide (COg). The Subpart E regulation is
applicable to each MWC unit of more than 45 metric tons (Mg) per day charging
rate [50 tons per day (tpd)]. The industrial-coirenercial-institutional steam
generating units NSPS covers MWC units (with steam-generating capability)
that commenced construction after 1984 and limits particulate emissions to
0.1 lb/million Btu heat input, or approximately 0.05 gr/dscf corrected to
12 percent COg. The Subpart Db regulation is applicable to MWC units (with
steam generating capability) that have a heat input capacity of more than
100 million Btu/hr, which equates to a capacity to process roughly 250 tpd or
more of municipal solid waste (MSW).
In Section 102 of the Hazardous and Solid Waste Amendments of 1984
Congress directed that a report be prepared on the magnitude of dioxin risks
from MWC's and ways in which dioxin emissions could be minimized. In 1986,
petitions were filed by the Natural Resources Defense Council (NRDC) and the
States of New York, Connecticut, and Rhode Island requesting regulation of
MWC's under Sections 111 and 112 of the CAA. In response, the EPA Office of
Air and Radiation (OAR), Office of Solid Waste (0SW) and Office of Research
and Development (ORD) prepared a report to Congress, which included a pre-
liminary assessment of air emissions and risks from MWC facilities. (See
Appendix H for risk information.) Based on the results of this assessment,
This document does not address incineration of medical waste, wastewater
sludge, or hazardous wastes. Medical waste incineration is not currently
regulated by NSPS, but is being investigated. The incineration of sludge is
regulated by an NSPS (40 CFR 60 Subpart 0) and also by regulations developed
under the Clean Water Act (40 CFR Part 503 Subchapter 0). Hazardous waste
incineration is regulated under RCRA authority (40 CFR Part 264 Subpart 0).
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the Agency concluded, in 1987, that there is a need for additional regulation
of MWC emissions from both new and existing facilities because: (a) new
MWC's are likely to be significant sources of criteria pollutant emissions;
(b) MWC emissions contain a wide variety of constituents including CDD'sa,
CDF's3, other potentially toxic organics, heavy metals, and acid gases that
can have adverse effects on public health and welfare; and (c) the MWC
industry has a potential for significant growth over the next 20 years. It
was decided at that time that it was more appropriate to regulate MWC
emissions under Sections 111(b) and 111(d) of the CAA than under Section 112.
On July 7, 1987, an advanced notice of proposed rulemaking (ANPRM) for
both new and existing MWC's was published in the Federal Register
(52 FR 25399). The notice announced the intent to regulate air emissions
from MWC's under Section 111 of the CAA. Section 111(b) is designed to
require new sources to apply control technologies to minimize emissions and
prevent future air pollution problems. Section 111(d) is designed to control
emissions of designated pollutants with health and/or welfare effects from
existing sources. Standards developed under Section 111 are to reflect best
demonstrated technology (BDT) defined as "best systems for continuous
emission reduction which (taking into consideration the cost of achieving
such emission reduction, and any nonair quality health and environmental
impact and energy requirements) the Administrator determines has been
adequately demonstrated for a category of sources". The BDT may be either a
technology that has been applied to the source category being investigated or
a technology that is considered to be applicable based on the Administrator's
judgment.
The existing NSPS for MWC's (Subpart E and Subpart Db) will be superseded
by a new NSPS (Subpart Ea) which will regulate a designated pollutant that is
not regulated under Sections 108 to 110 or 112 of the CAA. The regulation of
the designated pollutant under Subpart Ea will invoke Section 111(d) for the
issuance of emission guidelines to be used by the States in developing
emission standards for existing MWC units.
In this and subsequent discussions, CDD/CDF means the combined emissions of
tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofurans. See
Appendix E for additional discussion of this parameter.
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The ANPRM Federal Register notice also described operational guidance
issued to permitting authorities by OAQPS on June 26, 1987, which identified
best available control technologies that are considered to be demonstrated
and should be required for new MWC's applying for permits. The guidance
stated that a dry scrubber followed by either a fabric filter (FF) or
electrostatic precipitator (ESP) are "available" technologies for effective
control of sulfur dioxide (SC^) and particulate matter (PM) emitted by MWC's,
and that these technologies are also effective in controlling emissions of
other potentially toxic organic and heavy metal pollutants, and acid gases
other than S02- The guidance also stated that combustion controls are an
available technology for the control of organic pollutants as well as carbon
monoxide (CO) emitted by MWC's. The guidance stated that all of these
technologies were reliable and reasonably affordable for new MWC units.
The ANPRM also presented a schedule for standards development activities.
As described in the notice, proposal of the 111(b) standards of performance
for new sources and-the issuance of draft 111(d) guidelines for existing
sources is planned for November 1989. Promulgation of the 111(b) standards
and the issuance of final 111(d) guidelines is planned for December 1990.
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3.0 DESIGNATED POLLUTANT
New MWC's will be regulated under Section 111(b) of the CAA. One or
more designated pollutants (pollutants not regulated under Section 108
to 110 or 112) will be regulated, thus invoking section 111(d) of the CAA.
Section 111(d) regulations in 40 CFR 60.20 through 60.29 state that pollu-
tants may be designated for control because of health and/or welfare effects.
The provisions for development and approval of State plans to apply the
Section 111(d) emission guidelines are somewhat more stringent if a pollutant
is designated for health reasons rather than for welfare reasons alone. For
MWC's the designated pollutant will be health-based and activate the more
stringent 111(d) requirements.
The designated pollutant will be "MWC emissions". The emissions from
MWC's are a complex mixture of numerous pollutants which affect health and
welfare. In particular, MWC particulate matter (PM) emissions contain,
various metals which have carcinogenic and non-carcinogenic health impacts.
Acid gases emitted from MWC's include hydrogen chloride (HC1), which has
health and welfare effects. Organic emissions from MWC's, in particular
CDD/CDF, also are potentially carcinogenic. In combination, these effects
support a health-based designation of MWC emissions under Section 111.
As stated in the CAA, Section 111 regulations are to be established at
levels that "reflect the emission reduction associated with the performance
of best demonstrated technology (BDT)." As described in Section 5.0, the
control technologies that can be applied to MWC's generally are not selective
for controlling a single pollutant, but control a broad range of pollutants
found in MWC emissions. Therefore, in determining BDT, the designation of
MWC emissions will permit consideration of the overall effectiveness of
various techniques in reducing the broad range of pollutants found in MWC
emissions, and maintaining reductions on a continuous basis over the life of
the MWC plant.
Section 8.0 and Appendix B describe emission limits and monitoring
requirements that would be used to ensure continuous reductions in MWC
emissions. As described in those sections, "MWC emissions" as a whole cannot
be measured, but measurement and monitoring of a limited number of key
pollutants and parameters will ensure reductions in overall MWC emissions.
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4.0 MUNICIPAL WASTE C0MBUST0R PROFILE
4.1 TYPES OF COMBUSTOR DESIGN
There are three main types of technologies used to combust MSW: mass
burn, modular, and refuse-derived fuel-fired (RDF) technologies. A fourth
type, employing fluidized-bed combustion (FBC) technology, is less common.
While these are the main types of MWC technologies, there are variations
within these categories, and there are designs that incorporate features of
more than one type.
Mass Burn Combustors. Mass burn combustors are field-erected units
covering a wide size range with individual combustors (units) ranging in size
from 50 to 1,000 tpd of MSW combusted. There are typically two or three
combustors per plant, and plant capacities range from about 100 to 3,000 tpd
MSW. The technology is called mass burn because the waste is combusted
without any preprocessing other than removal of items too large to go through
the feed system. Virtually all new mass burn combustors are expected to
include waterwall furnace designs for waste heat recovery. Some older
facilities have refractory-lined walls without any heat recovery.
Modular Combustors. Modular combustors also burn waste without
preprocessing, but are usually shop-fabricated, small units ranging in size
from 5 to 120 tpd of MSW per combustor. Plants typically have one to four
combustors (although a few have more), and plant capacities typically range
from about 15 to 400 tpd MSW combusted. Modular units are typically dual-
chambered combustors. Depending on the design, combustion air is supplied to
the primary chamber either in excess of the stoichiometric amount required
for complete combustion (modular excess air MWC) or at substoichiometric
levels (modular starved air MWC). A secondary combustion chamber is used
after the primary chamber to introduce additional air to complete the
combustion process. Although many existing modular combustors do not have
heat recovery, the majority of new modular combustors are expected to
incorporate heat recovery.
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Refuse-Derived Fuel-Fired. The third class of MWC burns RDF. Processed
and shredded municipal waste, regardless of the degree of processing per-
formed, is broadly referred to as RDF. The degree of processing can vary
from simple removal of bulky items accompanied by shredding for direct firing
in MWC's, to extensive processing to produce a finely divided fuel suitable
for co-firing in pulverized coal-fired boilers. Some MWC's designed to
combust RDF combust only RDF, while others combust a mixture of RDF and other
wastes such as wood or coal (termed "mixed waste firing"). In addition, a
few boilers initially designed to combust pulverized coal may add some RDF as
a supplemental fuel (termed "co-firing"). Most RDF units are medium to large
size units with the size of individual combustors ranging from 300 to
1,000 tpd capacity. Plants typically have two to four combustors, and RDF
plant sizes range from 600 to 4,000 tpd capacity.
Fluidized-Bed Combustors.' In FBC, the waste burns in a turbulent bed of
heated noncombustible material (typically sand). There are two basic types
of FBC systems: bubbling-bed combustors and circulating-bed combustors.
Both burn RDF, sometimes mixed with other fuels. Typical FBC combustor sizes
for existing and planned units are 200 to 500 tpd, and plant sizes range from
about 300 to 1,000 tpd capacity.
4.2 MODEL PLANTS - SECTION 111(b) NSPS
Municipal waste combustors that commence construction after proposal of
the NSPS (scheduled for November 1989) will be considered "new" facilities
subject to the new NSPS (Subpart Ea). Using projections of the growth in
combustion of MSW developed by Franklin Associates, it is estimated that
about 54,000 tpd of new MWC capacity will become subject to the NSPS in the
1 2
5-year period after proposal (1990-1994). ' It is expected that about 60
new MWC plants (150 individual combustors) will commence construction within
this time period.
To project the distribution of new MWC's covered by the NSPS, information
on facilities in advanced planning or early construction stages was used,
because it is expected that typical combustor types and plant sizes for new
MWC's would be similar to MWC's that have been recently built or are under
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construction. These distributions indicate that of the projected total
design capacity subject to the NSPS, 60 percent will be mass burn, 29 percent
3
RDF, 3 percent modular, and 8 percent FBC facilities. In terms of the
number of individual combustors, 57 percent will be mass burn, 20 percent
RDF, 15 percent modular, and 8 percent FBC.
Twelve different model plants were developed to represent new MWC
facilities subject to the NSPS. New model plants were selected to represent
each common type of combustor design and typical sizes were selected within
each MWC design type. Where there was great size variation within a category
(such as mass burn), multiple model plants were developed (e.g., small,
medium-size, and large). Other considerations in new model plant selection
were annual operating hours and heat recovery ability. While most large new
MWC plants are expected to.operate continuously and produce steam and
electricity for sale, some smaller modular and mass burn plants are expected
to operate fewer hours or not to produce electricity.
The twelve model plants include three mass burn/waterwal1, one mass
burn/refractory, one mass burn/rotary combustor, two RDF, one modular excess
air, two modular starved air, and two FBC facilities. These model plants are
listed in Table 4-1. This table also shows the projected number of flew
2 4
facilities corresponding to each model plant. '
4.3 MODEL PLANTS - SECTION 111(d) EMISSION GUIDELINES
There are over 200 plants or 450 individual combustors that will be
subject to the Section 111(d) emission guidelines. This includes both
combustors at existing plants that are currently operating and "transitional
plants" that were not operating as of March 1988, but will commence
construction prior to November 1989, when the NSPS and emission guidelines
will be proposed. The 450 combustors reflects an increase of about
80 percent in the number of existing combustors since publication of the June
1987 Report to Congress. On a capacity basis, roughly 58 percent of these
111(d) units are mass burn facilities, 24 percent are RDF, 6 percent are
5
modular, and 12 percent are FBC or other unique designs. In terms of number
of combustors, 40 percent are mass burn, 11 percent are RDF, 38 percent are
modular, and 11 percent are FBC or other unique designs.
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TABLE 4-1. MODELS FOR NEW MWC PLANTS FOR SECTION 111(b) NSPS
I.D. No. and
Combuator Type
Model
Unit Size,
(tpd)
Number of
Units Per
Plant
Model Plant
Capacity,
(tpd)°
Annual
Operatlg
(hours)
Energy
Recovery
Fuel
Distribution of New Plants TotaL
Number Number of Capacity
of Plants Combustors (tpd)
1. MB/WW
2. KB/WW
3. MB/WW
4. MB/R£F
5. MB/RC/WW
6. RDF
7. RDF
8. MI/EA
9. KI/SA
10. Ml/SA
11. FBC (BB)
12. FBC (CFB)
TOTAL
100
400
750
250
350
500
500
120
25
50
450
450
200
800
2,250
500
1,050
2,000
2,000
240
50
100
900
900
5,000
8,000
8,000
8,000
8,000
8,000
8,000
8,000
5,000
8,000
8,000
8,000
100X MSW
100Z MSW
100X MSW
100X MSW
100X MSW
100X RDF
50X RDF/
50X wood
100X MSW
100X MSW
100X MSW
100X RDF
100X RDF
17
7
8
3
3
5
3
3
2
6
2
4
63
34
14
24
6
9
20
12
6
4
12
4
8
153
3,400
5,600
18,000
1,500
3,150
10,000
6,000
720
100
600
1,800
3.600
54,500
MB/WW ¦ mass burn/vatervall
MB/REF ¦ mass burn/refractory
MB/RC/WW « mass burn/rotary combustor/vatervall
RDF ¦> refuse-derived fuel
MI/EA » modular lnclnerator/excess air
MI/SA ¦ modular Incinerator/starved air .
FBC ¦ fluidlzed-bed combustion
BB ¦ bubbling bed
CFB ™ circulating fluldlsed-bed
b
Tons per day of waste (or other fuel) combusted per combustor.
°Tons per day of waste (or other fuel) combusted for the total plant.
**24 hrs/day x 333 days/yr * 8,000 hr/yr
100 hrs/vk x 50 wk/yr - 5,000 hr/yr
e
S ¦ steam generation, E * electricity generation, N - no energy recovery.
^Plants expected to commence construction in 5-year period after proposal of NSPS (1990-1994).
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Seventeen model plants were developed to represent the existing and
transitional MWC population subject to the 111(d) guidelines. These include
three mass burn/refractory models, four mass burn/waterwall models, four
RDF's, four modular, and two rotary waterwall models. These are listed in
Table 4-2. The table also shows the number of plants that correspond to each
model pi ant.®'^
The existing and transitional models represent each common type of
combustor design. Some of the existing designs include good combustion
practices (GCP) while others do not. All models representing transitional
MWC's have GCP, since this is typical of newer units. The models were also
selected to reflect the size ranges within each design type, the types of air
pollution controls at existing and transitional facilities, heat recovery
capabilities, and typical operating hours. While these models represent the
great majority of existing and transitional combustors, there are a few
combustors of unique designs not represented by a model.
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TABLE 4-2. MODELS FOR EXISTING AND TRANSITIONAL MWC PLANTS FOR SECTION 111(d) EMISSION GUIDELINES
Hod* 1
Number of
Model Plant
Annual
a
Distribution of Existing
and Transitional MWC'a
Total
I.D. No. and
Combustor Type
Unit Size,
(tpd)
Unit Per
Plant
Capacity,
48
14.300
Total
209
>4 50
105,000
Coutlnued
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TABLE 4-2 (CONCLUDED). FOOTNOTES
aMB/REF/TG • mass burn/refractory/traveling grate
MB/REF/RG ¦* mass burn/refractory/reciprocating grate
MB/REF/RK - mass burn/refractory/rotary kiln
MB/UW ¦ mas* burn/watervall
RDF ¦ refuse-derived fuel
MI/EA ¦ modular lnclnerator/excess air
MI/SA ¦ modular Incinerator/starved air
MB/RC/WW - mass burn/rotary combustor/watervall
b
Tons per day of HSU or RDF combusted per combustor. All model combustors burn 100 percent MSW or RDF.
CTons per day of MSW or RDF combusted for the total plant. All model plants burn 100 percent MSW or RDF.
d
N - no energy recovery
S • steam generation
e
GCP «• good combustion practices
ESP - electrostatic precipitator
WS - wet scrubber
*E - existing MWC's (operating as of March 1988)
T ¦ transitional HWC*s (MWC's not operating as of March 1988, but under construction
or expected to coosoence construction by November 1989, when Section 111(d)
emission guidelines are proposed).
a
This includes some older plants that are of unique designs as well as FBC's. The models
represent the moat c ©croon existing and transitional MWC designs, however, no models were
developed to represent unusual designs of which there are only one or two MWC's.
**lt is assumed only 2 of 3 combustors operate at a time.
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5.0 EMISSION CONTROL TECHNOLOGY AND PERFORMANCE
Municipal waste combustor emissions are mixtures of components which
include PM, metals, CDO/CDF, and acid gases such as S0£ and HC1.
There are basically three approaches to controlling emissions from
MWC's. The first approach is to alter the combustion process to reduce
emissions of organics including CDD/CDF, sometimes called combustion control .
or GCP. The second is adding pollution control equipment to control
emissions of PM, metals, and acid gases, and obtain additional CDD/CDF
control. The third approach involves separation of materials prior to
combustion, and exclusion of certain materials from combustion. These
approaches are not exclusive, and can be used together.
5.1 COMBUSTION CONTROL
Good combustion practices include the proper design, construction,
operation, and maintenance of an MWC. The use of GCP can minimize emissions
of CDD/CDF and their precursors by promoting more thorough combustion of
these pollutants. An integral part of GCP is proper operation of the MWC.
As discussed in Appendices A and B, operator training and certification along
with continuous monitoring of operating parameters will assure that GCP are
understood and implemented on a continuous basis.
Following discharge from the combustor, additional CDD/CDF can form from
precursors which have not been destroyed in the combustor. The CDD/CDF forms
in the presence of fly ash in the exhaust gas.7 Destruction of precursors
and exhaust gas cooling can prevent or minimize this secondary formation.
Exhaust, gas cooling can be achieved by water sprays, dilution air, or by the
addition of heat exchanger surface area.
Use of GCP including exhaust gas cooling to 450°F or below can achieve
3
CDD/CDF emission levels of 300 ng/Nm or less for new plants on a continuous
basis. Existing combustors can be retrofitted with GCP to achieve emission
levels of 500 ng/Nm^ or less on a continuous basis.
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5.2 PARTICULATE MATTER CONTROL
The most frequently used PM control devices at MWC's are electrostatic
precipitators (ESP's) and fabric filters (FF's).a These devices control MWC
PM emissions, which include both total and fine particulates, and metals that
are in particulate form.*3 Although other PM control technologies (such as
cyclones, electrified gravel beds, and venturi scrubbers) have been used at
MWC plants in the past, they are infrequently applied and are not likely to
be used at future MWC plants. The PM emission rates from ESP's on existing
MWC's vary depending on ESP size (specific collection area). Large, well-
designed ESP's can achieve total PM emission levels of 0.01 gr/dscf or less
at 7 percent Oj. This PM performance level can also be achieved by FF's.
Metals of concern emitted from MWC units include arsenic, beryllium,
cadmium, chromium, lead, mercury and nickel. All of these metals, except
mercury, are removed by ESP's or FF's with the fine particulates. Data
indicate that wel1-designed ESP's or FF's operated at 450°F or less remove
over 97 percent of arsenic, cadmium, and lead and about 99 percent of
beryllium, chromium, and nickel from MWC exhaust. Because the metals content
of MSW being combusted is variable, metals concentrations in the MWC exhaust
gases vary from plant to plant. Because of great variability from plant to
plant and the limited amount of metals test data for different plants, outlet
metals concentration emission limits cannot be specified. However, the use
of ESP's or FF's to comply with the PM emission limit will achieve high
metals removal efficiency in any case.
Mercury has a high vapor pressure and remains as a vapor in flue gas at
temperatures of about 450°F. No mercury control is achieved by ESP's whether
used alone or in conjunction with acid gas control. Moderate mercury reduc-
tion is achieved when FF's are used with acid gas control systems (see
Section 5.4).
aFor further description of ESP's and FF's, and for definition of other terms
and acronyms, see the Glossary in Section 12.0.
^In the remainder of this paper, these emissions are referred to simply as
PM.
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5.3 GOOD ACID GAS CONTROL (DRY SORBENT INJECTION/ESP)
Dry sorbent injection (DSI) technologies have been developed primarily
to control acid gas emissions.3 However, when DSI is combined with flue gas
cooling and an ESP, control of CDD/CDF, PM, and metal emissions are achieved.
Two primary subsets of DSI technologies exist. One approach referred to as
duct sorbent injection, involves injecting dry alkali sorbents such as
hydrated lime into flue gas downstream of the combustor outlet and upstream
of the particulate control device. The second approach, referred to as
furnace sorbent injection, injects sorbent directly into the combustor.
Dry sorbent injection is particularly attractive for existing MWC's
[111(d)] where it can be applied with the existing ESP without the need to
retrofit a new PM control device. For new MWC's [111(b)], both the DSI and
the PM control device must be purchased. For new applications a FF is
usually less expensive than an ESP, and DSI/FF technology is used. Dry
sorbent injection/FF systems can achieve the same or greater control of MWC
pollutants as DSI/ESP systems.
There are limited data on performance of DSI systems. Based on these
data, new MWC's with DSI/ESP systems can meet a CDD/CDF limit of 75 ng/Nm3.
Existing facilities that have been retrofitted with GCP and then apply
DSI/ESP systems can meet a limit of 125 ng/Nm3.
Dry sorbent injection systems can achieve a 40 percent reduction in SO2
emissions or an outlet SO2 concentration of 30 parts per million by volume
(ppmv) at 7 percent Og on a 24-hour average basis. An 80 percent reduction
in HC1 emissions or an outlet concentration of 25 ppmv is achievable on a
24-hour average basis.^
A PM emission limit of 0.01 gr/dscf is achievable for MWC's equipped
with DSI followed by ESP's.
Dry sorbent injection/ESP systems achieve 97 percent or greater removal
of arsenic, cadmium, and lead, and 99 percent removal of beryllium, chromium,
and nickel. Little or no mercury control is achieved by DSI/ESP systems, and
a control percent of zero is assumed.
aMWC acid gas emissions include HC1 and SO-. Control performance levels for
these two gases are discussed individually in the remainder of this paper.
pmw/059b
88-5.bac
5-3
-------
5.4 BEST ACID GAS CONTROL (SPRAY DRYER/FABRIC FILTER)
Lime spray drying systems followed by FF's were initially developed to
control SO2 and HC1 emissions. However, the system also controls CDD/CDF,
PM, and metal emissions including mercury. In the spray drying process, lime
slurry is injected into the spray dryer and reacts with acid gases. The
water in the slurry evaporates to cool the flue gas. The fly ash and reacted
sorbents are removed by the FF. Spray dryer/fabric filter systems represent
the best add-on control technology for MWC's. Therefore, throughout the cost
and emissions analyses presented in this paper, SD/FF systems have been the
technology basis of "best acid gas control".
Spray dryer/fabric filter systems achieve outlet CDD/CDF concentrations
of less than 10 ng/Nm^.^
Spray dryer/fabric filter systems can achieve an 85 percent reduction in
SO2 emissions or an outlet concentration of 30 ppmv at 7 percent 0£ on a
24-hour average basis. A 95 percent reduction in HC1 emissions or an outlet
concentration of 25 ppmv is achievable on a 24-hour average basis.
A PM emission limit of 0.01 gr/dscf is achievable by all MWC's equipped
with SD/FF systems.
Typically, SD/FF systems achieve 99 percent removal of all metals except
mercury. Mercury removal of 70 percent or greater is also achieved.
5.5 MUNICIPAL SOLID WASTE MATERIALS SEPARATION
Municipal solid waste materials separation is the separation of certain
components from the waste stream, such as noncombustible materials, prior to
combustion in an MWC. Available data have shown reduced emissions of some
metals with application of materials separation. Appendix F discusses the
feasibility of separating materials from the waste stream, the potential
impacts of materials separation on air pollutant emissions from MWC's, and
other potential impacts associated with materials separation.
pmw/059b
88-5.bac
5-4
-------
6.0 NEW MWC BASELINE, CONTROL OPTIONS, AND MODEL PLANT ANALYSIS
[Section 111(b) NSPS]
6.1 BASELINE AND CONTROL OPTIONS FOR NEW MWC PLANTS
The different emission control technologies discussed in Section 5.0
were analyzed for new plants. The costs that would result and emission
reductions achieved relative to baseline using these control options were
calculated for each of the model plants (see Section 4.0) representing the
new MWC population. In Section 8.0 these control options will be combined to
form regulatory alternatives for Section 111(b) standards development.
The baseline level of control for new MWC units represents the level
achieved without additional regulation. Under the regulatory baseline, it is
assumed that all new MWC's will be designed to incorporate 6CP and the level
of PM control required under current NSPS (Subparts E and Db). Presently,
new units smaller than 50 tpd are not regulated by the NSPS and have PM
emissions of about 0.1 gr/dscf. New units larger than 50 tpd but smaller
than 100 million Btu/hr heat input (approximately 250 tpd) are limited to
0.08 gr/dscf PM under existing NSPS (40 CFR 60, Subpart E). New units
greater than 100 million Btu/hr heat input are limited to 0.05 gr/dscf PM
under existing NSPS (Subpart Db). Acid gas controls would not be required
under either Subpart E or Db, and are not included in the regulatory baseline.
The three control options examined for new plants are listed below in
order of increasing stringency.
Option A: GCP and best PM control
Option B: GCP and good acid gas control with best PM control (DSI/ESP)
Option.C: GCP and best acid gas control with best PM control (SD/FF)
Table 6-1 shows the emission levels or percent reductions for CDD/CDF,
PM, and acid gases associated with each of these three control options for
new MWC's.4
pmw/059b
88-6.bac
6-1
-------
TABLE 6-1. EMISSION LEVELS ACHIEVABLE WITH CONTROL OPTIONS FOR NEW PLANTS4
Emission
Levels or %
Reduction^
Pollutant
Units of
Measure
Baseline
Option A
Option B
Option C
CDD/CDF
ng/Nm^
300
300
75
10
PM
gr/dscf
0.1, 0.08,
0.05
0.01
0.01
0.01
so2
%
reduction
0%C
0%
40%d
85%d
HC1
%
reduction
0%C
0%
80%e
95 %e
Depends on MWC unit size. Combustors with unit sizes of 50 tpd or less
are not currently subject to 40 CFR 60 Subpart E, and typically emit
0.1 gr/dscf. Those over 50 tpd are subject to Subpart E and may not emit
more than 0.08 gr/dscf. Combustors with unit sizes over about 250 tpd are
subject to Subpart Db and may not emit more than 0.05 gr/dscf.
^Option A = GCP and best PM control.
Option B = GCP, good acid gas control by dry injection, and best PM control.
Option C = GCP, best acid gas control by spray drying, and best PM control.
cBaseline SOg emissions are 200 to 300 ppmv at 7 percent 0£, and baseline HC1
emissions are 500 ppmv at 7 percent Og.
dA lower SOg emission limit of 30 ppmv is achievable.
eA lower HC1 emission limit of 25 ppmv is achievable.
pmw/059b
88-6.bac
6-2
-------
6.2 MODEL PLANT COST ANALYSIS
Total annualized costs of control were calculated for each model plant
under each control option.4 Table 6-2 shows the total annualized cost of
each control option for each model plant. One way to examine these increased
costs is in terms of the increased cost of control per ton of MSW combusted.
To put these numbers in perspective, MSW disposal costs incurred by the
general public for combustion of waste typically range from about $60 to over
$100/ton MSW (including collection, transportation, combustion, and ash
disposal). A typical household generates about 0.87 tons/yr of MSW.
Figure 6-1 presents the increased annualized. cost ($/ton MSW) versus model
plant capacity for Options A, B, and C.
As expected, Figure 6-1 shows that the increased annual cost per ton of
MSW, is highest for Option C, which includes best acid gas control (SD/FF),
and is lower for good acid gas control or PM control alone (Options B and A,
respectively). One significant observation that emerges from Figure 6-1 is
that the increased MSW disposal costs resulting from the control options are
much higher for small plants than for large plants, particularly under
control Options B and C which include acid gas controls. As shown in
Figure 6-1, the cost of best control (Option C) is generally about $8 to
$15/ton MSW for larger model plants, but increases rapidly for small plants,
ranging up to about $70/ton MSW for the 50 tpd modular model plant.
Increasing costs for small plants are also shown for good acid gas control
(Option B). Costs of this technology are generally below $10/ton MSW, but
increase for the smaller models up to about $50/ton MSW for the smallest
model.
Increased capital costs for add-on controls over baseline MWC plant
costs show a similar trend to annualized costs. For example, the increased
capital cost for Option C is shown in Figure 6-2. The percent capital cost
increases for larger plants are generally less than 20 percent, while the
smaller plants show greater capital cost increases (over 200 percent for the
4
smallest model plant).
In Section 8.0 these observations are considered in developing
regulatory alternatives for analysis.
pmw/059b
88-6.bac
6-3
-------
TABLE 6-2. SUMMARY OF ANNUALIZED COSTS OF CONTROL.OPTIONS FOR
NEW 111(b) MWC MODEL PLANTS
Model
PI ant
Annualized
Cost (S106l
bv Control
Option0
No.
Type3
Total Plant ,
Capacity (tpd)
Baseline
A B C
(Incremental over baseline)
1
MB/WW
200
5.28
0.03
0.67
1.20
2
MB/WW
800
15.20
0.11
1.80
2.73
3
MB/WW
2,250
32.86
0.30
4.14
5.92
4
MB/REF
500
12.60
0.13
1.51
2.57
5
MB/RC
1,050
20.62
0.11
2.28
3.56
6
RDF
2,000
35.70
0.28
4.60
6.59
7
RDF (Co-fired)
2,000
37.47
0.26
3.86
5.84
8
MI/EA
240
4.69
0.05
0.68
1.08
. 9
MI/SA
50
o o
>—• CT>
Q.
0.20
0.51
0.75
10
MI/SA
100
1.94
0.11
0.55
0.80
11
FBC (BB)
900
19.30
0.00
1.08
2.61
12
FBC (CFB)
900
19.30
0.00
1.74
2.61
MB/WW = mass burn/waterwal1
MB/REF = mass burn/refractory
MB/RC = mass burn/rotary combustor
RDF = refuse-derived fuel
MI/EA = modular incinerator/excess air
MI/SA = modular incinerator/starved air
FBC =¦ fluidized-bed combustor
BB = bubbling bed
CFB = circulating fluidized-bed
^tpd = tons per day.
cBaseline costs include cost of combustor with GCP and baseline PM control
(0.1 or 0.08 or 0.05 gr/dscf depending on combustor size)
Option A = GCP and best PM control (0.01 gr/dscf)
Option B = GCP, good acid gas control by dry injection, and best PM control.
Option C = GCP, best acid gas control by spray drying, and best PM control.
^Cost in parentheses corresponds to incremental cost (over the baseline of
PM = 0.1 gr/dscf) of achieving PM control to 0.08 gr/dscf at 7 percent 0?
using an ESP and temperature control to 450 F.
pmw/059b
88-6b.tbl
6-4
-------
CONTROL OPTION A
NEW wwc UNITS - i 1 1(b)
Ot ' i
(fhousonos)
IOTA*. PLANI CAPACITY (fONS/OAT)
CONTROL OPTION B
NCW MWC UMTS - 11 1(b)
t I
( ThOHMAdl)
TOTAL PlAMT CAPACITY (TOMS/OAT)
CONTROL OPTION C
NCW MWC UMTS - 11 Kb)
(Thousand!)
TOTAi PlAMT CAPACITY (TOnS/OaV)
gure 6-1. Increased annual cost versus 111(b) MWC model
plant capacity for Control Options A, B, and C.
6-5
-------
100
90
80
70
60
50
40
30
20
10
0
CONTROL OPTION C
NEW MWC PLANTS - 111(b)
(Thousands)
TOTAL PLANT CAPACITY (TONS/DAY)
Figure 6-2. Percent capi cost increase versus 111(b)
model plant capacity for Control Option C.
-------
7.0 EXISTING MUC BASELINE, CONTROL OPTIONS, AND MODEL
PLANT ANALYSIS [Section 111(d) Emission Guidelines]
7.1 BASELINE AND CONTROL OPTIONS FOR EXISTING MWC PLANTS
The emission control technologies discussed in Section 5.0 were analyzed
for retrofit control of existing plants. The costs that would result and
emission reductions achieved relative to baseline using these control options
were calculated for each of the MWC model plants (see Section 4.0)
representing the existing and transitional MUC population. In Section 8.0
these retrofit control options will be combined to form regulatory
alternatives for development of Section 111(d) emission gui-delines.
The regulatory baseline level of combustion and add-on emission control
varies for each model plant depending on the combustor type, unit size, age,
and prevalence of air pollution control devices (APCD's) at existing and
transitional MWC facilities represented by the model plant. Available
emission data were examined to select baseline emission rates for each model
plant. In some cases, the model plant is already controlled at baseline to
the level of some of the control options.
The four retrofit control options examined for existing plants are
listed below in order of increasing stringency.
Option A: GCP
Option B: GCP and best PM control
Option C: GCP and good acid gas control with best PM control (DSI/ESP)
Option D: GCP and best acid gas control with best PM control (SD/FF)
The emission levels or percent reductions of CDD/CDF, PM, and acid gases
associated with each of. these control options are shown in Table 7-1.6
7.2 MODEL PLANT COST ANALYSIS
Table 7-2 shows the total annualized APCD costs of each of the four
control options for existing and transitional 111(d) model plants.® One way
pmw/059b
88-7.bac
7-1
-------
TABLE 7-1. EMISSION LEVELS ASSOCIATED WITH CONTROL OPTIONS FOR EXISTING PLANTS6
b
Emission Levels or Percent Reductions
Pollutant
Unit of
Measure
Baselinea
Option A
Option B
Option C
Option 0
CDD/CDF
ng/Nm^
200 - 5,250
500
500
125
10
PM
gr/dscf
0.01 - 0.33
0.33
0.01
0.01
0.01
so2 J
'o reduction
0%c
0%
0%
40%d
85%d
HC1 ?
'o reduction
o
o
0%
0%
B0%e
95%e
aBaseline values vary by model plant depending on combustor design and operation,
and type of PM control.
^Option A = GCP and baseline PM control
Option B = GCP and best PM control
Option C = GCP, good acid gas control by dry injection, and best'PM control
Option D = GCP, best acid gas control by spray drying, and best PM control.
cBaseline S0? emissions are 200 to 300 ppmv at 7 percent 0? and baseline HC1
emissions are 500 ppmv at 7 percent 0^.
dA lower SO^ emission limit of 30 ppmv is.achievable.
eA lower HC1 emission limit of 25 ppmv is achievable.
pmw/059b
88-7d.tbl
-------
6
TABLE 7-2. SUMMARY OF ANNUALIZED COST OF CONTROL OPTIONS FOR EXISTING AND TRANSITIONAL 111(d) MWC MODEL PLANTS
6 d
Model Plant Annualized APCD Costs (S10 Over Baseline) bv Control Option
Total Plant ^
No. Type* Representation Capacity (tpd)C Option A Option B Option C Option D
1
MB/REF/TG
E
750
1.3
1.9
3.0
6.6
2
MB/REF/RG
E
240
0.8
1.3
2.0
2.8
3
MB/REF/RK
E
900
0.4 .
0.4
2.1
8.0
4
MB/WU
E & T
2,250
0.1
1.1
3.8
9.9
5
MB/WW
E & T
1,080
0.1
0.1
2.7
6.1
6
MB/WU
E
200
0.3
0.7
1.4
2.4
7
RDF
E
2,000
1.7
1.7
4.3
12.6
8
RDF
E
600
0.8
0.8
2.8
9
MI/SA
E fc T
100
0.2
0.5
0.9
10
MI/SA
E & T
SO
0.1
0.3
0.7
11
MI/EA
E
200
0.0
0.2
0.7
12
MB/RC/WW
E
500
0.1
0.5
1.6
13
MI/EA
T
420
0.0
0.3
1.0
2.0
14
MB/UU
T
200
0.0
0.5
1.3
2.2
15
RDP
T
2,000
0.0
0.0
2.6
9.0
16
RDF
T
600
0.0
0.0
1.9
4.2
17
MB/RC/UU
T
500
0.0
0.5
1.6
3.0
*MB/REF/TG • mass bum/refractory/traveling grate
MB/REF/RG » mass burn/refractory/reciprocating grate
MB/REF/RK ® mass bum/refractory/rotary kiln
MB/WW ¦ mass burn/vatervall
RDF ¦¦ refuse-derived fuel
MI/EA ¦ modular lnclnerator/excess air
MI/SA «=» modular incinerator/starved air
MB/RC/WW » mass burn/rotary combustor/vatervall
b
E ¦ Existing} T- Transitional
c
tpd - Tons per day
d
Option A — CCP and baseline PM control
Option B " GCP and best PM control (0.01 gr/dscf)
Option C - GCP, good acid gas by dry Injection, and best PM control
Option D • GCP, best acid gas control by spray drying, and best PM control
pinw/059b
Table-7.2
-------
to examine these increased costs is in terms of the increased cost of control
per ton of MSW combusted. To put these numbers in perspective, MSW disposal
costs incurred by the general public for incineration of waste are typically
in the range of $60 to over $100/ton MSW (including collection,
transportation, combustion, and ash disposal). A typical household generates
about 0.87 tons/yr of MSW. In general, the costs of adopting the various
control options for existing model plants show the same trend as new model
plants (see Section 6.0), but are higher because of APCD retrofit costs.
Figure 7-1 shows the increased disposal cost for Options A, B, C, and D. As
with new plants, a significant observation that emerges from Figure 7-1 is
that the added cost for emission control is much greater for smaller plants,
especially for acid gas controls.
For the larger plants, the increased cost of maximum control (Option D)
is about $20/ton MSW, while the increase for smaller plants is almost
S75/ton MSW. The cost of adding best PM control (Option B) or good acid gas
control (Option C) is also much higher for small plants, while there are
relatively lower cost impacts on large plants for these control technologies
(see Figure 7-1). Costs for Option C (which includes good acid gas control)
range up to about $50/ton MSW for the smallest model plant, while costs of
Option B (GCP and best PM control) are about $26/ton MSW for the smallest
model plant. The cost of GCP (Option A) (Figure 7-1) is relatively
inexpensive compared to options including acid.gas control. Cost per ton of
MSW for GCP depends primarily on whether a model MWC plant includes GCP in
the baseline, and secondarily, increases for the smaller plants. Generally
GCP retrofit costs range from less than Sl/ton MSW to about $10/ton MSW
combusted.
In Section 8.0, these observations are considered in developing
regulatory alternatives for analysis.
pmw/059b
88-7.bac
7-4
-------
CONTROL OPTION A
EXISTING MWC UNITS - m(d)
(Thousands)
TOTAL PLANT CAPACITY (TONS/OAT)
CONTROL OPTION B
EXISTING MWC UNITS - 111(d)
(Thousands)
TOTAL PUNT CAPACITY (TONS/DAY)
Figure 7-1. Increased annual cost versus 111(d) MWC model
plant capacity for Control Options A and B.
7-5
-------
CONTROL OPTION C
EXISTING UWC UNITS - 111(d)
(Thousands)
TOTAL PLANT CAPACITY (TONS/DAY)
CONTROL OPTION D
EXISTING MWC UNITS - 111(d)
z
o
1/1
o
CJ
3
Z
Z
<
1 2
(Thousands)
TOTAL PLANT CAPACITY- (TONS/DAY)
Figure 7-1 (Continued).
Increased annual cost versus 111(d)
MWC model plant capacity for Control
Options C and 0.
7-6
-------
8.0 REGULATORY ALTERNATIVES
8.1 SUMMARY OF REGULATORY ALTERNATIVES
Regulatory alternatives represent the various regulations (i.e., NSPS
and emission guidelines) considered for new and existing MWC's. Requlatory
alternatives differ from the control options considered in Sections 6.0 and
7.0 in that the regulatory alternatives are based on a mix of different
control options for different size MWC plants and form a strategy for control
of the entire MWC population.
Table 8-1 presents regulatory alternatives analyzed in terms of control
technologies for new and existing facilities, while Table 8-2 presents the
regulatory alternatives in terms of emission rates that would be specified in
O
the actual regulations (i.e., NSPS and emission guidelines). Although the
same five regulatory alternatives were analyzed for both new and existing MWC
plants, this is not meant to imply that the same regulatory alternative would
necessarily be applied to both new MWC units (NSPS) and existing MWC units
(emission guidelines).
The regulatory alternatives reflect varying levels of control for
CDD/CDF, PM (and associated metals), and acid gases including HC1 and S02-
The regulatory alternatives also subdivide MWC plants into two size
categories since the model plant cost analysis (reviewed in Sections 6.0 and
7.0) indicated that the cost impacts associated with various control options
can vary significantly depending on plant size. The criteria for definition
of small and large MWC plants are discussed in Sections 8.2 and 8.3.
For new model plants, the regulatory baseline includes GCP for all
combustors and, except for combustors below 50 tpd capacity, PM control of
0.05 or 0.08 gr/dscf as required by Subpart Db or E (see Section 6.0). For
existing plants, the regulatory baseline combustion practices and PM emission
rates vary depending on the design of the model plant (see Section 7.0).
Regulatory Alternative I. The least stringent regulatory alternative
(Alternative I) shown in Table 8-1 requires emission reductions to levels
achievable with GCP for plants of all sizes and various levels of PM control
depending on plant size. For small plants (i.e., those with capacities below
pmw/059b
88-8.bac
8-1
-------
TABLE 8-1. TECHNOLOGICAL BASIS FOR REGULATORY ALTERNATIVES FOR
NEW AND EXISTING MWC UNITS - 111(b) AND 111(d)
Control Requirements by Total MWC Plant Capacity
(tons MSW/day)
Small plants
<250 tpd
Large plants
> 250 tpd
Regulatory
Baseline
New^
GCP
Moderate PM (0.08)
or no PM (0.1)
GCP
Moderate PM (0.08)
or Good PM (0.05)
Existing
Model-plant
specific
Model-pi ant
specific
Regulatory
A1 ternative
I
GCP
Moderate PM (0.08)
GCP
Best PM (0.01)
11A
GCP
Moderate PM (0.08)
GCP
Good acid gas
Best PM (0.01)
I IB
GCP
Good acid gas
Best PM (0.01)
GCP
Good acid gas
Best PM (0.01)
III
GCP
Moderate PM (0.08)
GCP .
Best acid gas
Best PM (0.01)
IV
GCP
Good acid gas
Best PM (0.01)
GCP
Best acid gas
Best PM (0.01)
aMSW = Municipal solid waste: total plant capacity.
kpM emissions assume no control <50 tpd unit (0.1 gr/dscf),
Subpart E 50-250 tpd unit (0.08 gr/dscf), and Subpart Db >250 tpd unit
(0.05 gr/dscf).
cGood acid gas control = dry sorbent injection into the furnace or duct
followed by an ESP.
^Best acid gas control = spray dryer, which is injection of slurried lime
into a vessel following the combustor followed by a FF.
pmw/059b
88-8a.tbl
8-2
-------
TABLE 8-2. POTENTIAL EMISSION LIMITS ASSOCIATED WITH 111(b) AND 111(d)
REGULATORY ALTERNATIVES
Control Levels bv Plant Capacity3'
Regulatory
Alternative Small plants Large plants
<250 tpd > 250 tpd
I
CDD/CDF-new
(CDD/CDF-existing)
PM
HC1
S02
APCD Temperature .
GCP/Operating Std.
300 ng/Nm~
(500 ng/Nm )
0.08 gr/dscf
no limit
no limit
450 F
d
300 ng/Nm,
(500 ng/Nm )
0.01 gr/dscf
no limit
no limit
450 F
d
IIA
CDD/CDF-new
(CDD/CDF-existing)
PM
HC1
so2
APcD Temperature
GCP/Operating Std.
300 ng/Nm^
(500 ng/Nm )
0.08 gr/dscf
no limit
no limit
450 F
d
75 ng/Nm^
(125 ng/Nm )
0.01 gr/dscf
80% or 25 ppmv
40% or 30 Dpmv
300 F (350 F)
d
I IB
CDD/CDF-new
(CDD/CDF-existing)
PM
HC1
SO-
APED Temperature
GCP/Operating Stds.
75 ng/Nm~
(125 ng/Nm )
0.01 gr/dscf
80% or 25 ppmv
40% or 30 Dpmv
300 F (350 F)
d
75 ng/Nm:?
(125 ng/Nm )
0.01 gr/dscf
80% or 25 ppmv
40% or 30 Dpmv
300 F (350 F)
d
III
CDD/CDF-new
(CDD/CDF-existing)
PM
HC1
so2
APCD Temperature
GCP/Operating Stds.
300 ng/Nmi?
(500 ng/Nm )
0.08 gr/dscf
no limit
no limit
450 F
d
10 ng/Nmi?
(10 ng/Nm )
0.01 gr/dscf
95% or 25 ppmv
85% or 30 ppmv
300 F
d
IV
CDD/CDF-new
(CDD/CDF-existing)
PM
HC1
SO,
APCD Temperature
GCP/Operating Stds.
75 ng/Nm,
(125 ng/Nm )
0.01 gr/dscf
80% or 25 ppmv
40% or 30 ppmv
300 F (350 F)
d
10 ng/Nm^
(10 ng/Nm )
0.01 gr/dscf
95% or 25 ppmv
85% or 30 ppmv
300 F
d
(Continued)
pmw/059b
88-8a.tbl
8-3
-------
TABLE 8-2. (concluded) FOOTNOTES
aCDD/CDF emissions shown in parentheses relate only to existing 111(d)
facilities. All PM, SO-, HC1 and temperature numbers relate to both new
111(b) and existing lllfd) facilities.
^All ppmv, ng/Nm^, and gr/dscf levels at 7 percent 02 in exhaust gas.
cFlue gas temperature at PM control device discharge.
^Good Combustion Practices (GCP)/Operating Standards will include
enforceable operating requirements for MWC's including:
1) MWC load range (80-100%)
2) Exhaust CO level (varies depending on MWC)
3) Flue gas temperature at PM control device inlet of 450 F
eNew MWC's could design DSI/PM control systems to operate at a temperature of
300 F. For existing MWC's that would be retrofit with OSI ahead of older
existing ESP's, a temperature of 350 F was selected to avoid possible
corrosion and other ESP operating problems.
pmw/059b
88-8a.tbl
8-4
-------
250 tpd MSW), PM emission limits correspond to moderate PM control
(0.08 gr/dscf). This is the same level currently required under Subpart E
for all MWC units larger than 50 tpd. However, under Alternative 1 this same
level would be applied to all small plants with no lower size cutoff. Large
plants (i.e., those with capacities of 250 tpd or greater) are required to
achieve best PM control (0.01 gr/dscf). No add-on acid gas controls are
required for any plant under this option. Emissions of CDD/CDF would be
3 3
reduced to 300 ng/Nm for new plants and 500 ng/Nm for existing plants based
on use of GCP. The PM controls required would achieve significant reductions
in metals emissions (with the exception of mercury), and the higher costs of
acid gas controls would not be incurred. Flue gas temperatures at the PM
control device would be limited to 450°F or less.
Regulatory Alternative IIA. Regulatory Alternative IIA is more
stringent than Regulatory Alternative I and requires emission reduction to
levels achievable with GCP and varying levels of PM and acid gas add-on
control depending on plant size. Control requirements and emission levels
for small plants are the same as Alternative I. For large MWC plants, which
have greater annual emissions potential, good acid gas control (i.e., based
on DSI) and best PM control are required. For new large plants CDD/CDF is
3 3
reduced to 75 ng/Nm , while existing large plants would achieve 125 ng/Nm .
Under Alternative IIA, small plants are allowed a lower cost and less
efficient CDD/CDF control (GCP) which would avoid the relatively greater cost
impacts of add-on acid gas controls for smaller MWC plants.
Regulatory Alternative IIB. Regulatory Alternative I IB is more
stringent than IIA, and requires emission reductions to levels achievable
with GCP, good acid gas control (i.e., based on DSI), and best PM control for
all MWC plants, including small-sized plants. This results in reduction of
CDD/CDF emissions as well as reductions in acid gas emissions for all MWC
plants, but has higher costs for small plants than Alternatives I or IIA.
Regulatory Alternative III. Regulatory Alternative III requires
emission levels based on GCP, best acid gas control (i.e., based on spray
drying) and best PM control on large-sized MWC plants, reducing CDD/CDF
emissions to 10 ng/Nm3 for large plants. Compared to Alternative I IB, this
pmw/059b
88-8.bac
8-5
-------
alternative requires more stringent control of large plants, but less
stringent control of small plants. Small plants are required to achieve
emission levels based on use of 6CP plus moderate PM control, but no acid gas
controls.
Regulatory Alternative IV. Regulatory Alternative IV is the most
stringent alternative, and like Alternative III, is based on emission levels
achievable with GCP, best acid gas control (i.e., based on spray drying), and
best PM control for large plants. For small plants, emission levels
corresponding to GCP, good acid gas control (i.e., based on OSI), and best PM
control would be required. The requirements for small plants are, therefore,
more stringent than under Alternative III. Regulatory Alternative IV has the
lowest emissions but the highest cost.
Relationship to OAQPS Operating Guidance. Operating guidance for new
source review (NSR) permits was issued on June 26, 1987. The guidance
specified the1 use of "a dry scrubber followed by either a fabric filter or an
ESP" for new plants which are subject to NSR review (i.e. plants larger than
250 tpd capacity). The term "dry scrubber" would include spray dryers and
other equivalent acid gas control systems. Therefore, the guidance is
similar to Regulatory Alternative III, which is based on SD/FF control for
large MWC's, but does not require acid gas control for MWC's plants smaller
than 250 tpd. Since issuance of the guidance, about 15 MWC plants
(more than 25 individual units) larger than 250 tpd have been permitted and
all have used acid gas control followed by best PM control systems. Most
have used SD/FF technology.
8.2 SMALL PLANT VERSUS LARGE PLANT DEFINITION
The 250 tpd total plant capacity used to define small versus large
MWC plants was selected after examination of the impacts of applying the
different control options to the various size MWC plants (see Sections 6.0
and 7.0). As used in Sections 6.0 and 7.0 and in the regulatory
alternatives, MWC plant capacity is the aggregate capacity of MWC units on
site. For 111(b) the aggregate capacity of new MWC's would be used to
determine plant capacity. For 111(d) the aggregate capacity of existing
pmw/059b
88-8.bac
8-6
-------
MWC's would be used to determine plant capacity. Figures 6-1 and 7-1 show
that annual control cost impacts are greater for smaller plants, and that
incremental control costs begin to increase more quickly for plants below
about 250 tpd. Furthermore, it is consistent with the size cutoff used for
NSR permit review. The 250 tpd size would have the effect of classifying
most modular MWC's as "small" plants and most other MWC's as "large" plants.
The distinction between small and large plants allows higher efficiency
control technologies to be applied to a large percentage of MWC capacity but
a lower percentage of MWC units by numbers. As shown in Figure 8-1, the
large MWC plants (plants with capacities of 250 tpd or greater) would include
95 percent of new MWC capacity, but only about 70 percent of new MWC units by
number. This means that small MWC plants (less than 250 tpd capacity)
account for up to 30 percent of the new MWC units by number, but only
5 percent of the new MWC capacity. By requiring higher efficiency control of
large plants under Regulatory Alternatives I, IIA, and III, most of the
capacity and emissions would be controlled and the economy of scale shown in
Figure 7-1 would result, but the higher cost impacts for smaller plants would
be avoided. Alternatives I IB and IV, on the other hand, would require all
plants, regardless of size, to install acid gas controls.
As shown in Figure 8-2, the large MWC plants include about 90 percent of
existing MWC capacity but only about 50 percent of the.existing MWC's by
number. This means that plants smaller than 250 tpd represent roughly
50 percent of the existing MWC combustors by number, but only 10 percent of
the existing MWC capacity.
pmw/059b
88-8.bac
8-7
-------
too -
90 -
•
80 -
(A
i
£
70 -
|
60 -
3
30 -
1
40 -
J
¦8
X -
§
i
» -
10 -
0 -
NEW IMC UNITS - 111(b)
NEW MWC UMTS - 111(b)
j
I
I
%
5
i
Figure 8-1. Cumulative number of plants and
capacity vs. plant size.
pmw/059b
88-8.bac
8-8
-------
EXISTING UWC PIAKTS - "1(d)
-r
1.2
(Thousand*)
Tool Rant StenanaMwt
EXISTING IMC PLANTS - 111(4)
1.2
(Thousands)
Figure 8-2. Cumulative number of plants and
capacity vs. plant size.
pmw/059b
88-8.bac
8-9
-------
9.0 ECONOMIC AND ENVIRONMENTAL IMPACT ANALYSES FOR NEW MWC'S
9.1 EMISSION AND AIR QUALITY IMPACTS
9.1.1 National Emissions Impacts
The national baseline annual emissions and the annual emission
reductions of CDD/CDF, PM, SO-, HC1, and CO achieved under each of the five
2
regulatory alternatives for new MWC's [111(b)] are shown in Table 9-1.
Acid gas (SO2 and HC1) emissions account for the great majority of the total
emission reduction for all alternatives except Alternative I.
Figure 9-1 shows national emission reductions (as a percentage of
baseline emissions) of PM, CDD/CDF, and acid gases versus national cost for
each of the five regulatory alternatives. As shown in the figure, PM
reductions of over 70 percent are achieved under Regulatory Alternative I,
but no further PM reduction is achieved by Alternatives IIA or III because
all three alternatives require the same "best" PM control on large MWC
plants. SIightly. greater PM reductions (80 percent overall) are achieved
under Alternatives I IB and IV due to the addition of best PM controls on
small MWC plants. There are no reductions of CDD/CDF, or acid gases under
Alternative I. Increasing reductions of these pollutants are achieved under
Alternatives IIA, IIB, III, and IV as requirements for acid gas controls
become more stringent with each successive alternative. Specifically,
CDD/CDF control ranges from a 70 percent reduction under Alternative IIA to
over 90 percent reduction under Alternative IV. Total acid gas (SO^ plus
HC1) control ranges from a 60 percent reduction under Alternative IIA to
over 90 percent under Alternative IV.
9.1.2 Air Qualitv Impacts
Estimates of annual ambient concentrations for acid gases, mercury, and
g
lead emissions from new MWC model plants were developed. These results
were compared to threshold concentration levels beyond which adverse
health effects or welfare effects may occur.
SO.. The national primary (health related) ambient air quality
z 3
standard for S0£ is 80 ug/m (annual average). None of the model plants
exceed 10 percent of this level under baseline and ambient levels are
noticeably reduced under increasingly stringent regulatory alternatives.
pmw.059b
section.9
9-1
-------
TABLE 9-1. SECTION 111(b) NSPS NATIONAL TOTAL EMISSION REDUCTIONS2
Annual Emission
Reductions (tons/vr)
Regulatory
Alternative
CDD/CDF
PM
so2
HC1
CO
Baseline
Emi ssions
0.018
8,830
48,400
56,200
6,570
I
0
6,170
0
0
0
IIA
0.012
6,170
21,000
41,900
0
I IB
0.013
6,970
22,100
45,000
0
III
0.016
6,170
40,900
50,800
0
IV
0.017
6,970
42,000
53,900
0
Represents national baseline emissions
emissions are provided as a reference,
reductions relative to baseline.
- not emissions reduction. Baseline
All other values are emissions
pmw/059b
88-9a.tbl
9-2
-------
100
90
80
70
60
50
40
30
20
10
0
NATIONAL COST (MILLION $/YR)
Figure 9-1. National 111(b) compliance cost versus national
emissions reduction of PM, CDD/CDF, and acid
gases under each regulatory alternative.
-------
HC1. Predicted HC1 concentrations were compared to two measures of
health and welfare. The health reference level (HRL) of 7.0 ug/m^ (annual
average) is the level beyond which adverse noncancer effects may occur. The
3
welfare effects level is 3.0 ug/m (annual average), and is based on
materials damage effects.
At baseline and Alternative I, ambient HC1 concentrations at all twelve
model plants are below the 7.0 ug/m^ HRL, and only one plant is within 50
percent of the HRL. However, at baseline, four of the twelve model plants
3
exceed the 3.0 ug/m welfare level, with the highest concentration being
3
4.8 ug/m . Under Alternatives IIA, IIB, III, and IV, which require
increasing levels of acid gas control, all of the model plants are
controlled to less than the welfare level. The short-term HRL for HC1 is
3
150 ug/m (3-minute average). Modeling indicated that this level may be
exceeded by some existing plants which do not have acid gas controls and may
be exceeded by some new plants if acid gas controls are not required.
Lead. At baseline, ambient lead concentrations at all twelve model
plants are less than one percent of the 1.5 ug/m^ (annual average) standard.
With additional PM controls required under the regulatory alternatives, an
overall reduction of 93 to 98 percent in ambient lead concentration is
achieved.
Mercury. At baseline, ambient mercury concentrations at all twelve
3
model plants are less than 1 percent of the 1.0 ug/m (annual average)
NESHAP standard. Further reductions are achieved by the regulatory
alternatives that require acid gas controls in addition to PM controls.
Under the most stringent alternative, an overall reduction of up to
70 percent in ambient mercury concentration is achieved. These analyses do
not consider the contribution of indirect exposure pathways to total
exposure.
9.2 COST IMPACTS OF REGULATORY ALTERNATIVES
9.2.1 National Cost Impacts
To estimate national costs impacts for new Section 111(b) facilities
under each regulatory alternative, the costs of controls required for each
pmw.059b
section.9
9-4
-------
model plant (see Section 6.0) were multiplied by the number of plants to be
2 4
represented by each model (see Section 4.0). ' Table 9-2 shows the
annualized social cost and unit social cost (cost per unit of MSW combusted)
2
for the five regulatory alternatives. National costs given in this section
are for new MWC's that will be operating or under construction by the end of
the fifth year of implementation of the NSPS, which is 1994.
These estimates assume that all new facilities will adopt the pollution
control technologies and associated costs presented in the model plant
analysis, and will not change control technologies or revise or cancel plans
for MWC plant construction and switch to landfilling. EPA has an ongoing
analysis of how an NSPS might affect the selection of technology by the
industry, including whether some municipalities might scrap their planned
incinerators in favor of landfilling. Preliminary results of this analysis
indicate that the regulatory alternative selected will have very little
effect on the mix of incinerator types that will be used over the next five
years. The effect of the recycling or other alternatives to combustion and
landfilling have not be considered.
As shown in Table 9-2, national annual costs range from S6 million for
Regulatory Alternative I up to $167 million for Regulatory Alternative IV.
If Alternative 11A, IIB, III, or IV is selected, the national cost of
regulation of new MWC's will likely exceed $100 million, and the regulation
will be classified as a major rule. Section 11.0 compares these costs to
costs of other MSW-related regulatory programs.
9.2.2 Model Plant Cost Impacts
Potential impacts of the Section 111(b) NSPS on annual costs were
calculated for each of the new MWC model plants under each of the five
regulatory alternatives. Table 9-3 presents the ranges of the increased
annualized cost of control divided by the tons of MSW combusted ($/ton) for
each regulatory alternative and each size category of new model MWC plant.
Costs increase with the level of acid gas control required under a
regulatory alternative.
The impact of cost increases on tipping fees cannot be calculated and
can only be approximated. This is because these fees, which are payments to
MWC's for permission to dump MSW at an incinerator, are not, in general,
determined by the incremental cost of regulations, but are set by local
pmw.059b 9-5
section.9
-------
TABLE 9-2 SECTION 111(b) STANDARDS NATIONAL SOCIAL COSTSa
OF CONTROL (1987 $T
Regulatory
Alternative
AnnualizedfiSocial Cost
(siob/yr)
Annualized Social Cost
per ton MSW ($/ton) 'c
I
6
0.40
IIA
100
6.50
I IB
117
7.10
III
149
9.70
IV
167
10.20
Annualized social costs (control costs over baseline) are the sum of capital
costs annualized at 10 percent, and annual operating costs.
^Cost per ton of municipal solid waste (MSW) combusted in MWC's that incur
control costs. MWC's that incur no costs over baseline are excluded from
calculations.
CA typical household generates approximately 0.87 tons of MSW per year.
pmw/059b
flfl-Qa t-hl
Q_C
-------
TABLE 9-3. INCREASED COSTS (S/TON MSW) FOR NEW 111(b) MODEL PLANTS2
Cost Increase Compared to Baseline (S/ton MCUxa'b
Regulatory
Small Plants
Large Plants
Alternative
<250 tpd
>250 tpd
I
0-12
<1
IIA
0-12
4-11
I IB
8-43
4-11
III
0-12
7-15
IV
8-43
7-15
Baseline Tipping Feec
40
40
If it is assumed that increased costs are passed through to tipping fees,
then the values presented for increased costs of control per ton of MSW also
represent increases in tipping fees caused by the regulatory alternatives.
^A typical household generates approximately 0.87 tons of MSW per year.
Average tipping fee for MSW combustion in 1988 is S40/ton, and tipping fees
typically charged to MSW collectors range from SO to over SlOO/ton MSW.
Overall MSW collection, transportation, and disposal ranges from S60/ton to
more than SlOO/ton MSW.
pmw/059b
88-9a.tbl
9-7
-------
governments and may include subsidies. Furthermore, the NSPS will cover a
difficult-to-predict mix of public and private MWC's, and the division
between public and private ownership is important in conjecturing how MWC's
will pass along the cost of regulation. If it is assumed that all increased
costs are passed through to the tipping fee, then tipping fees for the
various size plants would increase by the amounts shown in Table 9-3. For
comparison, the average MWC tipping fee is currently about $40/ton MSW,
although tipping fees charged at individual sites can range from $0 to over
$100/ton MSW.*0 It is difficult to estimate baseline tipping fees because
of the wide variation and great uncertainty about how the economics of MSW
disposal might be affected by other EPA regulatory actions and by local
political reaction to the depletion of cheap landfill sites.
Table 9-3 shows that cost increases (and tipping fee increases, if
costs are passed through) for small model plants are in the range of SO to
$12/ton MSW under Regulatory Alternatives I, IIA, and III, which do not
require acid gas controls on plants with capacities below 250 tpd.
Alternatives 11B and IV, which require good acid gas controls on small
plants result in cost and tipping fee increases of $8 to $43/ton MSW. Cost
and tipping fee increases for large model plants increase across the
regulatory alternatives as add-on control requirements for large plants
become more stringent. Cost and tipping fee increases for large plants
range from less than $l/ton MSW under Alternative I to a range of $7 to
$15/ton MSW under Alternatives III and IV, which require best acid gas
controls for large plants.
9.3 PARTIAL BENEFITS ANALYSIS
9.3.1 Partial Benefits Analysis
Table 9-4 presents partial national total and incremental social
benefits, benefit to cost ratios, and partial net incremental cost of
pollutant emission reduction under each of the five regulatory
alternatives.** The benefits shown are only for emission reductions of PM,
SO2» and some organics (including CDO/CDF). Benefits are calculated based
primarily on reduced mortality, morbidity, and property deterioration.
Particulate matter emissions reduction is valued at $14,300/ton based on
site-specific analyses, and S0£ emissions reduction is valued at 51,140/ton.
pmw.059b
9-8
-------
TABLE 9-4 . PARTIAL NATIONAL SOCIAL BENEFITS-lll(b) PLANTS11
Regulatory
Alternative
Partial
Benefits
Total
Social
($10 /yr)
Incremental
Social Costs
Total
($106/yr)
Incremental
Overall
B/C Ratio
Incremental
B/C Ratio
Partial Net
Incremental Cost
(or Benefit)
($10 /yr)
I
B6
86
6
6
14.3
14 .3
(80) ^
11A
115
29
100
94
1.2
0.3
65
IIB
128
42C
117
111C
1.1
0.4C
69°
III
140
12
149
32
0.9
0.4
20
IV
153
25d
167
50d
0.9
0.5 d
25d
a
PH emissions reduction valuated at $14,300/ton.
SO^ emissions reduction valuated at $l,140/ton.
No benefit credit taken for HCi reduction. Benefits are in 1987 dollars.
b
( ) indicates a net benefit.
c
Incremental value for Alternative IIB over I. Alternative 1IA is an "inferior" alternative.
d
Incremental value for Alternative IV over IIB. Alternative III is an "Inferior" alternative.
jmjw 01)9
i;«l>lc 9-4
-------
Under Alternative I, the incremental benefit to cost ratio is greater
than 1, and incremental net benefits are realized. Under the remaining
alternatives, the overall benefit to cost ratio is about 1.0, but the
incremental benefit to cost ratio is less than 1; however, the benefit
values presented do not include all pollutants controlled at MWC's, and the
social benefits may be underestimated.
The lack of quantification of HC1 emission reduction benefits is
possibly the principal deficiency of the benefits analysis. Emissions
reductions of HC1 are greater than for any other pollutant, and about 1/3 of
the model plants have ambient HC1 concentrations that exceed the HC1 welfare
effects level at baseline (see Section 9.1.2). Regulatory Alternatives 11A,
11B, III, and IV reduce HC1 emissions by about 75 to 95 percent, and reduce
ambient concentrations to below the welfare effects level for all model
plants. Despite these potential benefits, no monetary evaluation of HC1
emissions is possible at this time. A dose-response function relating
health and welfare effects to reduced emissions of HC1 is not currently
available. Thus, while there are potential benefits associated with these
alternatives in terms of reduced HC1 emissions, the benefits analysis is
unable to take them into account at this time.
There are also other benefits not included in the analysis. Health
effects benefits for CDD/CDF control were calculated using direct exposures
only; indirect exposure levels are expected to be of similar magnitude as
direct exposure levels, but they were not quantitatively estimated, so
corresponding indirect exposure benefits under the regulatory alternatives
are not included in the valuation. Furthermore, health effects benefits
from reduced exposure to metals were not included, but have been at least
partially counted via the PM benefits analysis.
9.3.2 Implicit Valuation of HC1 Emissions
Table 9-5 presents the implicit valuation of HC1 emissions reduction
($/ton) under each regulatory alternative that would make incremental
benefits equal to costs. This implicit valuation of HC1 emissions is
derived by dividing the net incremental cost of control under a particular
alternative (see Table 9-4) by the incremental reduction in HC1 emissions.
pmw.059b
section.9
9-10
-------
TABLE 9-5. IMPLICIT VALUATION OF HC1 FOR BENEFITS TO EQUAL COSTS
Regulatory
Alternative
Net Incremental
Cost of Control ($10 /yr)
Incremental Reduction
in Emissions of HC1
(tons/yr)
Implicit Valuation
of HC1 for Benefits
to Equal Costs
(S/ton)
I
00
o
0*
0
0
IIA
65
41,900
1,530
I IB
69b
45,000b
1,530b
III
20-
5,800
3,430
IV
25c
8,900c
no
OO
o
o
a( ) indicates a net benefit.
^Incremental value fpr Alternative I IB over I. Alternative IIA is an "inferior"
alternative.
incremental value for Alternative IV over 11B. Alternative III is an "inferior"
alternative.
pmw.059b
-------
Under Alternatives I, IIA, and I IB, HC1 emissions valuations of about
$l,500/ton or less would make incremental benefits equal to incremental
costs. Hydrogen chloride emissions valuations of $3,400 and $2,800/ton
would make incremental benefits equal to costs under Regulatory Alternatives
III and IV, respectively. If other unquantified benefits (such as indirect
risks) could be considered, the implicit valuation for HC1 would be lower.
9.4 ECONOMIC IMPACTS
9.4.1 Economic Impacts on Households
To assess the economic impacts of the Section 111(b) NSPS, planned new
MWC plants were identified for which combustor technology and capacity are
specified. For these planned facilities, available service area and census
information were combined with control costs data imposed by the regulatory
alternatives to estimate household compliance costs. Other studies have
considered impacts on households to be "severe" if annual compliance cost
per household exceeds $220 or if annual compliance cost per household
12
exceeds one percent of median household income. Using these criteria,
none of the service areas examined have household impacts which are
considered to be severe under any of the regulatory alternatives. Under the
most stringent alternative (Regulatory Alternative IV), over 90 percent of
the service areas examined have household impacts less than $26 per year,
although some of the smallest communities examined have household impacts as
high as $100 per year.
These impacts are based on national average waste generation rates,
median incomes, and equal sharing of compliance costs by all households in a
service area. While on average, household impacts are not severe, some
households could be stressed in certain cases depending on actual waste
generated, actual household income, and the method by which local
2
authorities pass on the costs of the regulations to households.
9.4.2 Economic Impacts on Governmental Units
To assess economic impacts of the Section 111(b) NSPS on governmental
units (counties and municipalities), information on the estimated cost of
control for some planned MWC facilities was combined with financial and
pmw.059b
section.9
9-12
-------
other information on the governmental unit or units responsible for the MWC
facilities. These data were used to compute three measures of governmental
2 12
economic impact used in other studies. ' Economic impacts are considered
to be "severe" if both the following two conditions are met: 1) the sum of
total current debt service and additional debt service associated with
compliance to the regulation as a percent of total general revenues exceeds
15 percent, and 2) the sum of the average sewerage and sanitation cost per
household and the average control cost per household as a percent of median
household income exceeds 1 percent. Governmental units are also considered
to be severely impacted if a third condition is met: 3) control costs as a
percent of total general expenditures exceed 1 percent. Using these
criteria, the analyses indicate that the increased costs imposed by the
regulatory alternatives do not result in severe economic impacts on any
governmental units planning to construct new MWC facilities.
pmw.059b
section.9
9-13
-------
10.0 ECONOMIC AND ENVIRONMENTAL IMPACT ANALYSES FOR EXISTING MWC'S
10.1 EMISSION AND AIR QUALITY IMPACTS
10.1.1 National Emissions Impacts
The national baseline annual emissions and the annual emission
reductions of CDD/CDF, PM, SO2, HC1, and CO achieved under each of the five
regulatory alternatives are shown in Table 10-1 for existing MWC's
[111(d)].^ Acid gas (S02 and HC1) emissions account for the great majority
of the total emission reduction for all alternatives except Alternative I.
Figure 10-1 shows national emission reductions (as a percentage of
baseline emissions) of PM, CDD/CDF, and acid gases versus national cost for
each of the five regulatory alternatives. As shown in the figure, PM
reductions of about 60 percent are achieved under Alternative I, and
slightly greater PM reductions (70 percent overall) are achieved under
Alternatives 11B and IV. Due to the requirement of GCP under Alternative I
and varying degrees of acid gas control under Alternatives IIA, I IB, III,
and IV, increasing reductions of CDD/CDF emissions are achieved with each
successive alternative. Reductions of CDD/CDF range from 70 percent under
Alternative I to greater than 99 percent under Alternative IV. No
reductions of acid gas emissions are achieved under Alternative I, but
increasing reductions of acid gases are achieved under Alternatives IIA,
I IB, III, and IV. Control of total acid gases (SO2 plus HC1) ranges from a
55 percent reduction under Alternative IIA, to 90 percent reduction under
Alternative IV.
10.2 Air Quality Impacts
Estimates of annual ambient concentrations for acid gases, mercury, and
lead emissions from model plants representing existing MWC's were
g
developed. These results were compared to threshold concentration levels
beyond which adverse health effects or welfare effects may occur.
S0-. The primary (health related) national ambient air quality
z 3
standard for SO2 is 80 ug/m (annual average). None of the model plants
exceed 10 percent of this level under baseline, and the ambient levels are
reduced under increasingly stringent regulatory alternatives.
pmw.059
section. 10
10-1
-------
TABLE 10-1. SECTION 111(d) GUIDELINES NATIONAL TOTAL
EMISSION REDUCTIONS1,3
Annual Emission Reductions (ton/vrl
Regulatory
Alternative
CDD/CDF
PM
so2
HC1
CO
Baseline
Emissions
0.223
12,500
95,000
119,000
28,900
I
0.164
7,170
0
0
12,300
IIA
0.204
7,170
33,800
82,600
12,300
I IB
0.209
9,110
38,100
94,900
12,300
III
0.216
7,170
75,900
100,000
12,300
IV
0.221
9,110
80,200
112,000
12,300
Represents national baseline emissions
emissions are provided as a reference,
reductions relative to baseline.
- not emissions reduction. Baseline
All other values are emissions
pmw/059b
Table-10.1
10-2
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100
90
80
70
60
50
40
30
20
10
0
Figure 10-1. National
national
and acid
111(d) compliance cost versus
emissions reduction of PM, CDD/CDF,
gases under each regulatory alternative.
-------
HC1. Modeled HC1 concentrations were compared to three measures of
3
health and welfare. The health reference level (HRL) is 7.0 ug/m (annual
3
average). The welfare effects level is 3.0 ug/m (annual average), and is
based on materials damage effects. Because of concern that the existing
model plants used for evaluating ambient HC1 impacts might not represent the
actual "worst-case" for some of the older existing plants, four actual
"reasonable worst-case" plants were examined to assess ambient HC1 impacts.
These impacts were compared to the short-term (3-minute average) health
effects level of 150 ug/m^.
Under baseline and Regulatory Alternative I, ambient HC1 concentrations
3
at all eighteen model plants are below the 7.0 ug/m HRL, and only two
plants are within 50 percent of the HRL. However, at baseline, three of the
3
eighteen model plants exceed the 3.0 ug/m welfare level, with the highest
concentration being 4,8 ug/m^. Under Alternatives IIA, IIB, III, and IV,
which require increasing levels of acid gas control, all of the model plants
are controlled to less than the welfare level.
Using the actual reasonable worst-case plant approach, two of the four
plants, one large refuse-derived fuel-fired and one large mass
burn/waterwall plant, exceed the HC1 short-term health effects level of 150
ug/m^ at baseline. The two smaller modular plants used in the actual plant
analysis did not exceed the short term health effects level.
Lead. While baseline lead levels are higher for existing plants as
3
compared to new plants, all are still less than 5 percent of the 1.5 ug/m
(annual average) standard. The reason that existing plants have higher
levels is that there is little or no PM control on many small existing
plants. As PM control requirements become more stringent with each
regulatory alternative, ambient lead concentrations are controlled to less
than 1 percent of the 1.5 ug/m^ standard. The model plant with the highest
ambient concentration (rocking grate refractory) shows an overall reduction
of greater than 99 percent in ambient lead concentration for Alternatives
IIB and IV.
Mercury. At baseline, ambient mercury concentrations at all 18 model
plants are less than 1 percent of the 1.0 ug/m^ (annual average) NESHAP
pmw.059
section.10
10-4
-------
standard. Further reductions are achieved by the regulatory alternatives
requiring acid gas controls. Under the most stringent alternative, an
overall reduction of up to 70 percent in ambient mercury concentration is
achieved. As for new plants, this analysis does not consider the
contribution of indirect exposure pathways to total exposure.
10.2 COST IMPACTS OF REGULATORY ALTERNATIVES
10.2.1 National Cost Impacts
To estimate national cost impacts for existing and transitional
Section 111(d) MWC facilities under each regulatory alternative, the costs
of controls required for each model plant (see Section 7.0) were multiplied
by the number of plants to be represented by each model (see Section 4.0).
Table 10-2 shows the annualized social cost and unit social cost (cost per
13
unit of waste combusted) for the five regulatory alternatives.
These estimates assume that all plants subject to Section 111(d)
emission guidelines will be retrofitted with control technologies outlined
in the model plant analysis.® Closure of MWC's and switching to landfills
or reducing MSW combustion by other alternatives such as recycling are not
considered in these cost estimates. EPA has an ongoing analysis of how
Section 111(d) Guidelines might affect the selection of technology by the
industry, including whether some municipalities might scrap their existing
or planned incinerators in favor of landfilling. Preliminary results of
this analysis indicate that the regulatory alternative selected will have
very little effect on the mix of existing incinerator types.
As shown in the table, national annual costs range from $103 million
for Regulatory Alternative I to $640 million for Regulatory Alternative IV.
National costs for all the alternatives exceed $100 million per year.
Section 11.0 compares these costs to costs of other MSW-related regulatory
programs.
10.2.2 Model Plant Cost Impacts
Potential impacts of the Section 111(d) emission guidelines on annual
costs were calculated for each of the existing MWC model plants under each
of the five regulatory alternatives. Table 10-3 presents the ranges of
pmw.059
10-5
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TABLE 10-2. SECTION 111(d) GUIDELINES NATIONAL COSTS3
OF CONTROL (1987 S)1,3
Regulatory
Alternative
Annualized Social Cost
($io6/yr)
Annualized Social Cost
per ton MSW ($/ton) '
I
103
3.20
11A
264
8.20
I IB
339
10.50
III
565
17.50
IV
640
19.80
Annualized social costs (control costs over baseline) are the sum of
capital costs annualized at 10 percent, and annual operating costs.
k$ per ton of MSW combusted in MWC's that incur control costs. MWC's that
incur no costs over baseline are excluded from calculations.
CA typical household generates approximately 0.87 tons of MSW per year.
pmw/059b
T.LI . 1 a •%
10-6
-------
increased annualized cost of control divided by the tons of MSW combusted
($/ton) for each regulatory alternative and each size category of existing
13
model plant.
The impact of cost increases on tipping fees cannot be calculated and
can only be approximated. This is because these fees are generally not
determined by the incremental cost of regulation, but are set by local
governments and may include subsidies. Furthermore, the emission guidelines
would cover a mix of public and private MWC's, and the type of ownership
would affect how MWC's will pass along the costs of regulation. If it is
assumed that all increased costs are passed through to the tipping fee, then
tipping fees for the various size plants would increase by the amounts shown
in Table 10-3. For comparison, the average MWC tipping fee is currently
about $40/ton MSW, although tipping fees charged at individual sites vary
greatly and range from $0 to over $100/ton MSW.^
As shown in Table 10-3, control cost and tipping fee increases (if
costs are passed through) for the small model plants range from SO to
$17/ton MSW for Alternatives I, IIA, and III. Control cost and tipping fee
increases for small plants range from $9 to $44/ton MSW under Alternatives
IIB and IV which require acid gas controls for small plants. For large
plants, as regulatory requirements for acid gas control increase, control
costs and tipping fees increase. Cost and tipping fee increases for large
plants range from $0 to $6/ton MSW under Alternative I to a range of $11 to
$25/ton MSW under Alternatives III and IV which require best acid gas
controls for large plants. Cost increases under all of the alternatives
vary widely among model plants and are greatly influenced by the degree of
existing GCP or add-on emission controls present under the regulatory
baseline.
10.3 PARTIAL BENEFITS ANALYSIS
10.3.1 Partial Benefits Analysis
Table 10-4 shows partial national total and incremental social
benefits, benefit to cost ratios, and partial net incremental costs of
pollutant emission reduction under each of the five regulatory
alternatives.^ The benefits shown are only for emission reductions of PM,
pmw.059
10-7
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TABLE 10-3. INCREASED COSTS (S/TON MSW) FOR NEW 111(b) MODEL PLANTS13
Cost Increase Compared to Baseline fS/ton MSW)a'^
Regulatory
Small Plants
Large Plants
Alternative
<250 tpd
>250 tpd
I
0-17
0-6
IIA
0-17
4-12
I IB
9-44
4-12
III
0-17
11-25
IV
9-44
11-25
Baseline Tipping Fee0
40
40
If it is assumed that increased costs are passed through to tipping fees,
then the values presented for increased costs of control per ton of MSW also
represent increases in tipping fees caused by the regulatory alternatives.
^A typical household generates approximately 0.87 tons of MSW per year.
cAverage tipping fee for MSW combustion in 1988 is $40/ton, and tipping fees
typically charged to MSW collectors range from $0 to over $100/ton MSW.
Overall MSW collection, transportation, and disposal ranges from $60/ton to
over $100/ton MSW.
pmw/059b
Tahle-10.1
10-8
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TABLE 10-4. PARTIAL NATIONAL SOCIAL BENEFITS-lll(d) PLANTS11
Regulatory
Alternative
Partial Social
Benefits3 ($10 /yr)
Total Incremental
Social Coats ($10 /yr)
Total Incremental
Overall
B/C Ratio
Incremental
B/C Ratio
Partial Net
Incremental Cost
($10 /yr)
I
IIA
IIB
III
IV
ill
151
183
198
230
111
40
72b
15
*7°
103
264
339
565
640
103
161
236b
226
301C
1.1
0.6
0.5
0.4
0.4
1.1
0.2
0.3°
0.07
0.2 d
(8)
121
164°
211
254d
PM emissions reduction valuated at $14,300/ton.
SO^ emissions reduction valuated at $l,140/ton.
No benefit credit taken for HCL or CO reduction. Benefits are In 1987 dollars.
b( ) Indicates a net benefit.
c
Incremental value for Alternative IIB over I. Alternative IIA is an "Inferior" alternative.
Incremental value for Alternative IV over IIB. Alternative III is an "inferior" alternative.
purw. 0 39b
I able-10 U
-------
SOj, and some organics (including CDD/CDF). Benefits are calculated based
primarily on reduced mortality, morbidity, and property deterioration.
Particulate matter emissions reduction is valued at $14,300/ton based on
site-specific analyses, and SO2 emissions reduction is valued at $1,140/ton.
Under Alternative I, the incremental benefit to cost ratio is greater
than 1, and incremental net benefits are realized. Under the remaining
alternatives, both the overall and incremental benefit to cost ratios are
less than 1; however, the benefit values presented do not include all
pollutants controlled at MWC's, and the social benefits may be
underestimated.
The lack of quantification of HC1 emission reduction benefits is
possibly the principal deficiency of the benefits analysis. Emissions
reductions of HC1 are greater than for any other pollutant, and some of the
model plants have ambient HC1 concentrations that exceed the HC1 welfare
effects level at baseline (see Section 10.1.2). Regulatory
Alternatives IIA, I IB, III, and IV reduce HC1 emissions by about 70 to
95 percent and reduce ambient concentrations to below the welfare effects
level for all model plants. Despite these potential, benefits, no monetary
evaluation of HC1 emissions is possible at this time. A dose-response
function relating health and welfare effects to reduced emissions of HC1 is
not currently available. Thus, while there are potential benefits
associated with these alternatives in terms of reduced HC1 emissions, the
benefits analysis is unable to take them into account at this time.
There are also other benefits not included in the analysis. Health
effects benefits for CDD/CDF control were calculated using direct exposures
only; indirect exposure levels are expected to be of similar magnitude as
direct exposure levels, but they were not quantitatively estimated, so
corresponding indirect exposure benefits under the regulatory alternatives
are not included in the valuation. Furthermore, health effects benefits
from reduced exposure to metals were not included, but have been at least
partially counted via the PM benefits analysis.
10.3.2 Implicit Valuation of HC1 Emissions
Table 10-5 presents the implicit valuation of HC1 emissions reduction
($/ton) under each regulatory alternative that would make incremental
pmw.059
serfi nn . 10
10-10
-------
TABLE 10-5. IMPLICIT VALUATION OF HC1 FOR BENEFITS TO EQUAL COSTS
Regulatory
Alternative
Net Incremental
Cost of Control
($io6/yr)
Incremental Reduction
in Emissions of HC1
(tons/yr)
Implicit Valuation
of HC1 for Benefits
to Equal Costs
(S/ton)
I
(a)a
0
0
IIA
121
82,600
1,460
IIB
164b
94,900b
1,730b
III
211
5,280
40,000
IV
254c
17,500°
14,500c
a( ) indicates a net benefit.
''Value is incremental value for Alternative 11B over I. Alternative IIA
is an inferior alternative.
cValue is incremental value for Alternative IV over IIB. Alternative III
is an "inferior" alternative.
pmw.059b
table-10.5
10-11
-------
benefits equal to costs. This implicit valuation of HC1 emissions is
derived by dividing the net incremental cost of control under a particular
regulatory alternative (see Table 10-4) by the incremental reduction in HC1
emissions. Under Alternatives I, IIA, and I IB, HC1 emissions valuations of
less than $2,000/ton would make incremental benefits equal to incremental
costs. Hydrogen chloride emissions valuations of greater than $14,000/ton
would be needed to make incremental benefits equal to costs under Regulatory
Alternatives III and IV. For existing MWC's the noticeably higher cost for
SD/FF over DSI/ESP results in high incremental cost. This occurs because
the DSI technology (Regulatory Alternatives IIA and I IB) can be applied with
the existing ESP and only the DSI system must be retrofitted. For
Regulatory Alternatives III and IV, SD/FF is used, and both the SD and FF
must be retrofitted (the existing ESP is removed and scrapped). If other
unquantified benefits (such as indirect risks) could be considered in this
analysis, the implicit valuation of HC1 would be lower.
10.4 ECONOMIC IMPACTS
10.4.1 Economic Impacts on Households
To assess the economic impacts of the Section 111(d) emission
guidelines, existing and transitional MWC plants were identified for which
combustor technology and capacity are specified. For these facilities,
available service area and census information were combined with control
costs imposed by the regulatory alternatives to estimate household
compliance costs. Other studies have considered impacts on households to be
"severe" if annual compliance cost per household exceeds $220 or if annual
compliance cost per household exceeds one percent of median household
12
income. Using these criteria, none of the service areas examined have
household impacts which are considered to be severe under any of the
regulatory alternatives. Under the most stringent alternative (Regulatory
Alternative IV), 95 percent of service areas examined have household impacts
less than $62 per year, although, a few of the smallest service areas
examined have household impacts over $62, but less than $100 per year.
These impacts are based on national average waste generation rates,
median incomes, and equal sharing of compliance costs by all households in a
pmw.059
cortinn If)
10-12
-------
service area. While on average, household impacts are not severe, some
households could be stressed in certain cases depending on actual waste
generated, actual household income, and the method by which local
13
authorities pass on the costs of the regulations to households.
10.4.2 Economic Impacts on Governmental Units
To assess economic impacts of the Section 111(d) emission guidelines
on governmental units, information on the estimated cost of control for some
exiting MWC facilities was combined with financial and other information on
the governmental unit or units responsible for the facilities. These data
were used to compute three measures of governmental economic impact used in
12 13
other studies. ' Economic impacts are considered to be "severe" if both
the following two conditions are met: 1) the sum of total current debt
service and additional debt service associated with compliance to the
regulation as a percent of total general revenues exceeds 15 percent, and 2)
the sum of the average sewerage and sanitation cost per household and the
average control cost per household as a percent of median household income
exceeds 1 percent. Governmental units are also considered to be severely
impacted if a third condition is met: 3) control costs as a percent of
total general expenditures exceed 1 percent. Using these criteria, the
analyses indicate that the increased costs imposed by the regulatory
alternatives do not result in severe economic impacts on governmental units.
pmw.059
section.10
10-13
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11.0 RCRA SUBTITLE D PROPOSED RULES
Regulations pertaining to aspects of MSW disposal other than MWC air
emissions are currently under development. In particular, Resource
Conservation and Recovery Act (RCRA) Subtitle D regulations for MSW landfills
have been proposed. The cost and economic impacts associated with the
proposed Subtitle D regulations are included here for comparison to
the MWC air emission regulatory impacts described in Sections 9.0 and 10.0.
Other actions related to MSW disposal including the development of air
emission standards for MSW landfills, are under early stages of development,
and analysis of regulatory alternatives are not yet available for comparison.
Subtitle D regulations under RCRA proposed in the August 30, 1988,
Federal Reoister (53 FR 33314) would noticeably increase the cost of MSW
disposal in new and existing landfill sites. The proposed rule would require
existing landfills to provide for closure and post-closure care including
groundwater, surface water, and gas monitoring and to provide final cover
integrity. Additional regulations for new landfills require that sites be
developed with a liner as well as other detection and monitoring equipment
necessary to ensure the integrity of groundwater and surface water.
There are some methodological differences between the Subtitle D
analysis and the MWC analysis. Both analyses, in estimating impacts on
households and governmental units, match service area data to affected sites,
be they landfills or combustors. However, for the most part it has not been
possible to use the same service areas or data sources for both analyses.
The Subtitle D analysis relies on an extensive survey of existing landfill
sites. No parallel survey exists for MWC's, particularly for the as-yet
unbuilt MWC's. It is not possible to say whether this difference in data
bases exaggerates or diminishes apparent differences in impact measures of
the two types of regulations.
As described below, the cost impacts associated with the proposed
Subtitle D regulations are generally higher than those associated with the
MWC air regulatory alternatives discussed in this paper.
pmw/059b
88-11.bac
11-1
-------
National Cost Impacts. The proposed Subtitle D rule is estimated to
increase the national annualized cost associated with landfill disposal of
MSW at new and existing landfills by about $690 million to $880 million.
These increased national annual costs are higher than those associated with
all but the two most stringent regulatory alternatives examined for control
of air emissions for new and existing MWC's. For new MWC's, the most
expensive alternative (Alternative IV) costs less than $170 million. In
combination, the overall cost of control for new and existing plants would be
$109 million, $364 million, $456 million, $714 million, and $807 million for
Alternatives I, 11A, I IB, III, and IV, respectively. Combined costs for the
two most stringent regulatory alternatives for new and existing MWC's
(Alternatives III and IV) are more similar to the Subtitle D costs.
Increased Cost per ton of MSW. The Subtitle D regulations result in an
average increased disposal cost of $10 to $ll/ton of MSW disposed in
landfills. However, depending on landfill size and characteristics,
increased costs for individual landfills range from about $1 to $80/ton of
MSW. The average values are generally comparable to increased cost/ton MSW
for Regulatory Alternatives III or IV for new MWC's and Alternative I IB for
existing MWC's (see Tables 9-2 and 10-2). None of the MWC model plants incur
cost increases as high as $80/ton MSW under any of the regulatory
alternatives (see Tables 9-3 and 10-3).
The cost/ton MSW for the Subtitle 0 regulations are in the same range as
those for the MWC regulatory alternatives despite the fact that national
annualized costs are higher for the Subtitle D regulations because the
Subtitle D regulations impact more tonnage of MSW disposed.
Economic Impacts on Households. The proposed Subtitle D regulations for
MSW landfills result in an average annual cost increase for MSW disposal per
household of about $8 to $11; however, costs per household range up to about
$250 for a few communities. Using the same threshold for "severe" household
impacts defined in Sections 9.4 and 10.4, fewer than 0.1 percent of all
communities experience severe household impacts as a result of the proposed
Subtitle D regulations. As discussed in Sections 9.4 and 10.4, none of the
MWC regulatory alternatives cause communities to exceed the severe household
impacts threshold.
pmw/059b
88-11.bac
11-2
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12.0 GLOSSARY
MWC
MSW
RDF
PM
Acid Gases
CDD/CDF
GCP
ESP
pmw.059b
section.12
Municipal waste combustor. Any furnace (incinerator or steam
generator) used in the process of burning municipal solid
waste for the purpose of reducing the volume of the waste by
combustion.
Municipal solid waste. Refuse, which is municipal-type waste
consisting of a mixture of paper, wood, yard wastes, food
wastes, plastics, leather, rubber, and other combustible
materials, and noncombustible materials such as glass and
rock. Municipal solid waste does not include medical waste,
hazardous waste, or sludge.
Refuse-derived fuel. The combustible, or organic portion of
municipal waste that has been separated out and processed for
use as fuel. Processing may vary from simple removal of
noncombustibles and shredding to production of more finely
divided, pulverized fuel.
Particulate matter emitted from MWC's, including total PM,
fine particulates (or PM^g), and metals and organics that are
in particulate form.
Acid gases emitted from MWC's including sulfur dioxide (SC^)
and hydrogen chloride (HC1).
The combined emissions of tetra-through octa-chlorinated
dibenzo-para-dioxins and dibenzofurans.
Good combustion practices. Includes the proper design,
construction, operation, and maintenance of an MWC to minimize
combustor emissions.
Electrostatic precipitators. A high efficiency particulate
matter control device in which flue gas flows between a series
of high voltage discharge electrodes and grounded plates. The
PM becomes charged particles which are collected on the
grounded plates, and the dust layer is removed and collected
in a hopper.
12-1
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FF Fabric filter (baghouses). This is another high efficiency
particulate matter control device. Two types of FF's are
used. In a reverse-air FF, flue gas flows through unsupported
filter bags building the particulate up inside of the bags to
form a filter cake. When air is blown through the filter in
the opposite direction, the "bag" collapses, the filter cake
falls off and is collected. In a pulse-cleaned FF, flue gas
flows through supported filter bags leaving particulate on the
outside of the bags. Compressed air is blown through the
inside of the filter bag, the bag expands and the filter cake
falls off and is collected.
DSI Dry sorbent injection. Used primarily to control acid gas
emissions, and usually is followed by ESP. Dry sorbent
injection/ESP (or FF) also reduces emissions of CDD/CDF and
PM. Two primary subsets are: 1) duct sorbent injection which
involves injecting dry alkali sorbents (hydrated lime) into
the flue gas downstream of the combustor outlet and upstream
of the particulate control device; and 2) furnace sorbent
injection, which involves injection of the sorbent directly
into the combustor.
SD Spray dryer. Used to control acid gases, and is usually
followed by a FF. Spray dryer/FF also controls emissions
of CDD/CDF and PM. Lime slurry is injected into the spray
dryer; the water in the slurry evaporates to cool the flue
gas, and the lime reacts with acid gases to form salts that
can be removed by a PM control device.
pmw.059b
section.12
12-2
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13.0 REFERENCES
1. Franklin Associates, Ltd. 1988. Characterization of Municipal
Solid Waste in the United States, 1960 to 2000. Final report prepared
for U.S. Environmental Protection Agency.
2. Morris, Glenn E., et. al. (Research Triangle Institute). Economic
Impact of Air Pollutant Emission Regulations for New Municipal Waste
Combustors, Draft Report. (Prepared for the U.S. Environmental
Protection Agency. Research Triangle Park, North Carolina).
December 5, 1988 and Revisions, March 1, 1989, and April 12, 1989.
3. Radian Corporation. Planned and Projected Municipal Waste Combustors
Profile Update. (Prepared for the U.S. Environmental Protection
Agency. Research Triangle Park, North Carolina). EPA Contract
No. 68-02-4378, Work Assignment 31. May 1988. 27 pp.
4. Radian Corporation 111(b) Model Plant Description and Cost Report.
(Prepared for U. S. Environmental Protection Agency. Research Triangle
Park, North Carolina). EPA Contract No. 68-02-4378, Work
Assignment 31. September 1988.
5. Radian Corporation Municipal Waste Combustion Industry Profile -
Facilities Subject to Section 111(d) Guidelines. (Prepared for the
U. S. Environmental Protection Agency, Research Triangle Park,
North Carolina). EPA Contract No. 68-02-4378, Work Assignment 31.
September 1988. 20 pp.
6. Radian Corporation and Energy and Environmental Research Corporation.
Municipal Waste Combustion Retrofit Study, Draft Report. (Prepared for
the U. S. Environmental Protection Agency. Research Triangle Park,
North Carolina). September 15, 1988. 467 pp.
7. Vancil, M. A., and D. M. White. (Radian Corporation). Assessment of
Add-On Control Technology Performance for New Municipal Waste
Combustors. (Prepared for the U. S. Environmental Protection Agency.
Research Triangle Park, North Carolina). EPA Contract No. 68-02-4378.
June 1988. 112 pp.
8. Memorandum. Mead, R. C., and T. K. Moody (Radian Corporation) to Walt
Stevenson and Ron Myers, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina. Regulatory Alternatives for
Existing and New Municipal Waste Combustion (MWC) Facilities.
August 30, 1988.
9. Memorandum. Morrison, Rayburn M., PAB to Robert Ajax, EPA/SDB and Jim
Crowder, EPA/ISB. Preliminary Risk Analysis to Support Municipal Waste
Combustor New Source Performance Standards Development.
January 20, 1989.
pmw/059b
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10. Pettit, C.L. Tip Fees Up More Than 30% in Annual NSWMA Survey. Waste
Age. March 1989. pp. 101-106
11. Madariaga, B. (OAQPS/Ambient Standards Branch). Draft Benefits
Analysis of Air Pollution Emissions Regulations for Municipal Waste
Combustion. December, 1988.
12. Temple, Barker & Sloane, Inc., ICF, Inc., and Pope-Reid Associates.
Draft Regulatory Impact Analysis of Proposed Revisions to Subtitle D
Criteria for Municipal Solid Waste Landfills. (Prepared for the U.S.
Environmental Protection Agency, Office of Solid Waste.
Washington, DC). 1987.
13. Morris, Glenn E., et. al. (Research Triangle Institute). Economic
Impact of Air Pollutant Emission guidelines for Municipal Waste
Combustion, Draft Report. (Prepared for the U.S. Environmental
Protection Agency. Research Triangle Park, North Carolina.)
December 5, 1988 and Revisions, March 1, 1989, and April 12, 1989.
pmw/059b
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APPENDICES FOR BACKGROUND PAPER
-------
APPENDIX A. MWC OPERATOR TRAINING AND CERTIFICATION
Good operation of combustors and air pollution control systems will he:,
ensure continuous compliance with the NSPS for new MWC's and emission
guidelines for existing MWC's. Good operation can be achieved through
continuous monitoring of emissions and various operating parameters (see
Appendix B) and through proper training of operators, supervisors, and other
plant personnel. Thus, the Section 111 standards and guidelines could
require each MWC facility shift supervisor and chief facility operator to be
certified by the Amercian Society of Mechanical Engineers (ASME). Each MWC
facility could also be required to develop and implement a site-specific
training program for all other employees associated with the operation of the
MWC.
The ASME has developed a proposed certification program for MWC shift
supervisors and chief facility operators which consists of an initial
provisional certification followed by an operator certification.* To obtain
provisional certification, a candidate must demonstrate that certain basic
conditions of education and experience have been met and must pass a written
examination covering the basics of municipal waste combustion. The initial
provisional certificate, which is valid for 5 years, is not specific for any
particular MWC technology and is transferable.
After attainment of provisional certification and 6 months of experience
at a particular MWC facility, a chief facility operator or shift supervisor
may pursue operator certification. This certificate is issued upon passing a
site-specific oral examination on the operation, preventative maintenance,
and safety procedures at the facility. Operator certificates are valid only
for facilities of similar size and technology. They are valid for 3 years
and may be renewed upon demonstration that the operator has maintained
knowledge of the particular MWC technology and permit requirements. New
certificates are required upon transfer to a facility of a different size or
technology. ASME Certification would assure national consistency and would
allow individuals to transfer their certification from one State to another.
For other MWC personnel, training guidance could be provided in the NSPS
and emission guidelines by identifying a number of key training elements or
pmw/059b
appendix.a
A-l
-------
subject areas that must be addressed in the mandatory training program. The
development and implementation of the training program, however, would be the
responsibility of the individual MWC facility. The NSPS and emission
guidelines could also require each MWC plant to document their training
program in a manual or other type of document which illustrates how their
training program addresses these key elements of training. In addition, the
NSPS and emission guidelines could require each site to maintain a record of
the training provided to each employee.
pmw/059b
appendix.a
A-2
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APPENDIX B. SELECTION OF MONITORING REQUIREMENTS
Because MWC emissions are a complex mixture of pollutants, it is
impossible to measure or establish a single emission limit for "MWC
emissions" as a whole. Setting emission limits and monitoring requirements
for every pollutant found in MWC emissions would also be impractical and is
unnecessary. Control of the full range of this complex mixture of pollutants
can be achieved by focusing on a limited number of individual components, and
emission limits can be established for these individual components of MWC
emissions.
The limits that are established depend on the technology selected as
the basis for the NSPS and/or the emission guideline. Candidate technologies
and the types of pollutants they control are listed below:
(1) Good combustion practices (GCP) - organics
(2) PM control (ESP or FF) - MWC-PM, including particulate metals
(3) Acid gas control followed by PM control (DSI/ESP or SD/FF) - MWC-
acid gases, organics, MWC-PM, metals
A combination of (1) and either (2) or (3) is likely to be selected as
the basis for the NSPS and the emission guidelines (see Section 8.0 of the
background paper on regulatory alternatives).
Based on the technology selected as the basis for the standards and/or
guidelines, appropriate emission limits and monitoring requirements will be
established to ensure proper design, operation, and maintenance of the
control technology on a continuous reduction basis.
If the final standards or guidelines incorporate GCP, a CDO/CDF emission
limit will be set at a level achievable using GCP. An initial performance
test at start up and periodic retesting could be required. However, CDD/CDF
emissions cannot be monitored on a continuous basis. Therefore, in order to
ensure that GCP continue to be employed on a continuous basis, selected
operating parameters must be continuously monitored and operating standards
complied with on a continuous basis. These would include: CO emissions
level at the combustor outlet, MWC load level, and flue gas temperature at
the PM control device. The regulation would define allowable ranges for
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B-l
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these parameters for the more common types of MWC's. Where the regulation
did not define parameters for a certain MWC, the values of these parameters
would be determined during their CDD/CDF performance test. These operating
parameters would then be monitored continuously, and exceeding the levels
established in their CDD/CDF performance test would constitute a violation.
If a source wished to revise their operating parameters or widen the allowed
operating envelope for the parameters, a retest of CDD/CDF emissions would be
conducted.
If the standards or guidelines incorporate add-on PM control, a PM
emission limit could be set. This would ensure control of the fraction of
organics that are condensed in particulate form and other solid or
condensible non-criteria components of MWC emissions such as metals. An
initial compliance test would be required. Similar to CDD/CDF emissions, PM
emissions cannot be continuously monitored, but opacity can be monitored
continuously and used as a surrogate. The combination of a PM limit and
opacity monitoring requirements would ensure proper design, construction, and
operation of the PM control system.
If the final standards or guidelines incorporate acid gas control, a
lower CDD/CDF emission limit than that achieved through the use of 6CP alone
would be set since acid gas control systems achieve additional CDD/CDF
control. However, since CDD/CDF cannot be continuously monitored, continued
operation and maintenance of acid gas controls must be verified through
monitoring other pollutants or parameters. In addition to CDD/CDF control,
dry injection or spray drying systems control acid gases (SOg and HC1).
Hydrogen chloride monitoring is still under development, however, SC^
emissions are good indicators of the operation of these control systems.
Continuous monitoring of SO^ and APCD temperature would be required to ensure
proper operation of the acid gas control system.
Regardless of the ultimate "mix" of control technologies incorporated
into the final standards or guidelines, it would be desirable to provide some
flexibility in the monitoring requirements. For example, if the owner or
operator of a source believed that the pollutants and parameters specified
for monitoring were not the most pertinent and that monitoring of a different
pmw/059b
appendix.b
B-2
-------
set of parameters for a specific MWC unit would better ensure continued
control, he could petition for use of different parameters. These petitions
would need to lay out the different parameters suggested for monitoring and
discuss in some detail why these different parameters are more pertinent to
monitoring the operation of the system. The petitions would be examined and
approved or disapproved on a case-by-case basis.
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appendix, b
B-3
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APPENDIX C. NITROGEN OXIDES
C.l INTRODUCTION AND SUMMARY
Nitrogen oxide (NOx) emission control at new MWC's was investigated.
Available data on NOx emissions from MWC's include: (1) short-term N0X
emissions at 47 MWC's located at 32 different facilities and long-term N0X
emissions collected by continuous emission monitoring (CEM) from the MWC in
2
Mi 11 bury, MA ; and (2) short-term N0X emissions from Thermal DeNOx systems at
three MWC's in California. Analysis of the short-term NOx emissions data
from several full-scale MWC's suggests that combustion modification
techniques such as low excess air (LEA) may reduce N0X emissions. However,
the available data on combustion modification techniques are too limited and
contain too much scatter to define specific performance levels for an NSPS or
emission guideline. Data are available to support a conclusion that
selective noncatalytic reduction (SNCR) (specifically Thermal DeNOx), an
add-on NOx control technique, can achieve about 45 percent reduction in N0X
emission levels and would result in emissions of about 100 to 150 ppmv (at 7
percent Og).
The cost effectiveness of applying SNCR to new 111(b) MWC's was
assessed. Based on the twelve model plants described in Section 3.0 of this
background paper, the cost effectiveness of Thermal DeNOx ranged from about
$2,000 per ton of N0X removed for some of the largest model plants to
$23,000 per ton of N0X removed for the smallest model plant. These costs
would translate to about $2/ton MSW combusted for large MWC plants up to
almost $20/ton MSW for the smallest modular MWC's.
Four regulatory alternatives for N0X control (including the baseline or
"no control" alternative) were developed. Under the baseline alternative, no
N0X control would be required, and no cost or emission reduction would
result. Alternative 1 would require all new MWC plants above 1,100 tons per
day capacity to apply NO control technology. This would reduce national NO
A a
emissions by 9,400 tons/yr, and would result in national annualized costs of
$18 million/yr. Alternative 2 would require all new MWC plants above
250 tons per day capacity to apply N0X control technology. This alternative
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appendix.c
C-l
-------
would reduce national emissions by 13,700 tons/yr, and would result in
national annualized costs of $30 million/yr. Under Alternative 3, MWC plants
of all sizes would be required to apply N0X control. This alternative would
reduce national NOx emissions by 17,800 tons/yr and national control costs
would be $37 million/yr.
C.2 NITROGEN OXIDES EMISSIONS
Most of the emissions data available for assessing current levels of N0X
emissions were generated during MWC compliance tests. These tests are
generally conducted at the combustor's full load design operating conditions
and last from 1 to 3 hours. With the exception of one unit, combustor N0X
concentrations ranged from about 60 to 370 ppm at 7 percent O2. The
exception is one modular unit which had N0X emissions of 611 ppm. Table C-l
summarizes N0X emissions for the different combustor types.
Long-term CEM data were also collected at the Mi 11 bury MWC between
July 15, and September 15, 1988. Millbury incorporates GCP and has installed
a lime spray dryer followed by an electrostatic precipitator. During this
period, 1,439 valid hourly NOx measurements were recorded. A frequency
distribution of hourly N0X emission rates corrected to 7 percent 0£ is shown
in Figure C-l. These data are roughly normally distributed and individual
1-hour values range from about 30 ppm to 495 ppm, with a mean of about
260 ppm and a standard deviation of 46 ppm. This is consistent with the data
in Table C-l which shows that emissions from mass burn/waterwal1 units
average 240 ppm.
To assess the effectiveness of combustion modifications in controlling
N0X emissions, data from the parametric tests at Marion County, Oregon and
Quebec City, Canada were analyzed. Multivariate analyses of the effects of
combustor load, excess air, and overfire air distribution on N0X emissions
showed that each of these variables has some effect on N0X emissions.
However, due to the limited amount of data and scatter within the data, the
correlations were relatively low. Thus, no specific conclusions can be drawn
regarding the ability of these techniques to achieve specific emission levels
for use in establishing emission limits in an NSPS or a guideline.
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appendix.c
C-2
-------
TABLE C-l. SUMMARY OF NOx EMISSIONS DATA FROM MWC's
NO Emissions .
Combustor (ppmv at 7 percent Q>>)
Type Number of Units Average Range
MB/UU
23
240
145
- 370
MB/REF
8
155
60
- 240
RDF
5
265
195
- 345
MI/SA
5
215°
85
- 280
MI/EA
_6
^40
105
- 280
All Types
47
215d
60
- 370
MB/WW = mass burn/waterwal1
MB/REF = mass burn/refractory
RDF = refuse-derived fuel
MI/SA = modular incinerator/starved air
MI/EA =» modular incinerator/excess air
''All values rounded to the nearest 5 ppmv.
cExcludes one data point of 611 ppmv.
^Excludes one data point of 611 ppmv for a modular starved air facility.
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appendix.c
C-3
-------
MILLBURY CEM DATA ANALYSIS
0.15
0.14
0.13
0.12
0.11
£ 0.09
c
©
3 0.08
u
o
III 0.07
a>
= 0.06
o
a. 0.05
0.04
0.03
0.02
0.01
0
Outlet ppm NOX ® 7% 02 3 Represents 350-495
Outlet NOX vs Relative Frequency
<150155 165175185195205215225235245255265275285295305315325335345 a
Figure C-l. Frequency distribution of NOx emission rates.
-------
It should also be noted that other data collected from a mass burn
combustor at various overfire air rates showed increased CO and hydrocarbon
2
levels for decreased N0X emissions. In addition, two of the facilities with
above average N0X concentrations (Pinellas County and Marion County) have
reported very low CDD/CDF concentrations. Considered together, these data
suggest that the temperature and residence time requirements associated with
CDD/CDF destruction may contribute to N0X formation. However, considering
all available test data, no clear correlation between NOx emissions and
uncontrolled CDD/CDF emissions was observed, and it is premature to conclude
that all combustion modification techniques will increase CDD/CDF. Due to
these uncertainties, combustion modification techniques are not considered a
demonstrated technology for controlling N0X emissions from MWC's.
Add-on control techniques for reducing N0X emissions include selective
noncatalytic reduction (SNCR) and selective catalytic reduction (SCR).
Selective noncatalytic reduction refers to techniques in which a reducing
agent (such as ammonia or urea) is used to convert N0X to ^ without using a
catalyst to promote reduction. Existing SNCR processes include Exxon's
Thermal DeNOx, N0x0UT, and a urea/methanol injection method being developed
by EMCOTEK. To date, only Thermal DeNOx has been applied to MWC's in the
U.S. Therefore, discussion of SNCR methods is limited to Thermal DeNOx.
Potentially higher N0X reductions can be achieved with SCR, but at a higher
cost. There have been no commercial applications of SCR to MWC's in the U.S.
Thermal DeNOx reduces N0X emissions through injection of ammonia into
the convective heat transfer section of the combustor. To assess the
effectiveness of Thermal DeNOx, short-term N0X emissions data were analyzed
from the MWC's in Commerce, Long Beach, and Stanislaus County, CA.
Outlet N0X levels were measured during three short-term tests at each of
the California MWC's with Thermal DeNOx systems operating at their normal
injection rates. Outlet N0X concentrations averaged 90 ppm (at 7 percent 0£)
at Commerce, 56 ppm at Long Beach, and 93 ppm and 113 ppm at the two units at
Stanislaus County. Based on these tests, the N0X removal efficiency at
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appendix.c
C-5
-------
Commerce was 45 percent, and removals at Stanislaus County were near
65 percent. Long-term CEM data at Long Beach indicate removal efficiencies
of about 50 percent.^
Long Beach and Stanislaus County have reported formation of a visible
3 4
plume downstream of the stack. ' This plume is believed to be caused by
reaction of residual ammonia and chloride after the flue gas exits the stack.
The problem is most common at the Long Beach MWC where use of flue gas
recirculation to reduce N0X formation and variations in MSW heating value are
suspected of reducing gas temperatures near the ammonia injection points to
less than those needed for ammonia to react with N0X. The flue gas
recirculation system of Long Beach is also suspected of transporting
unreacted ammonia back to higher temperature combustion zones where it is
oxidized to form N0X.^ Performance of N0X control systems and potential
problems such as ammonia chloride plumes are dependent on site-specific MWC
design and operation.
Based on these data, Thermal DeNOx is a demonstrated technique for
reducing N0X emissions from new MWC's. Data from the first Thermal DeN0x
system installed on an MWC in the U.S. (Commerce, CA) indicate NOx emission
reductions of 45 percent are achievable. Emissions data from two more
recently installed units suggest emission reductions of 50 percent and
greater can be achieved with proper equipment design and operation, but these
data are limited due to the newness of these systems.
A potential concern about the use of Thermal DeNOx is that some data
show ammonia injected into the flue gas may reduce SD/FF control of mercury
emissions. Compliance tests at the Commerce, Long Beach, and Stanislaus
MWC's showed relatively high outlet mercury concentrations (180 to
500 ug/dscm at 7 percent 02), despite the fact that these MWC's have SD/FF
control systems in addition to Thermal DeNOx. At Commerce, the inlet was
also tested, and showed that there was little or no mercury removal across
the control system. This is unusual, since data for other MWC's with SD/FF
control systems show over 70 percent mercury removals. However, more recent
test data from Commerce indicated 74 to 90 percent mercury removal while the
ammonia injection system was operating. More data are needed to determine
pmw/059b
appendix.c
C-6
-------
whether ammonia injection reduces mercury control or whether there is another
explanation for the observed low mercury removals.
C.3 COST AND COST EFFECTIVENESS OF N0X CONTROL FOR MODEL PLANTS
The cost and cost effectiveness of Thermal DeNOx controls were assessed
for the 12 new 111(b) MWC model plants described in Section 3.0 of this
background paper.® The Thermal DeNOx system includes a low pressure air
compressor, ammonia storage tank, ammonia vaporizer, injection nozzles,
piping, and associated instrumentation. In addition, a continuous NOx
monitor for each combustor is included to ensure continuous compliance. The
increased annual cost associated with N0X removal for each model plant, the
annual cost per ton MSW combusted, the associated emission reduction, and the
cost effectiveness of control ($/ton N0X removal) are summarized in
Table C-2. These costs are based on 45 percent N0X reduction, and
electricity and ammonia costs of $0.046/kwh and $200/ton, respectively.
Capital costs are annualized based on a 15 year economic life and a
10 percent real interest rate. As shown in Figure C-2, control of smaller
plants is less cost effective than for larger plants. Estimated
cost-effectiveness values for the model plants range from $1,810 to
23,300 per ton N0X removed.
C.4 REGULATORY ALTERNATIVES AND IMPACTS
Three regulatory alternatives were examined to control N0X emissions
from new MWC's under Section 111(b) of the CAA. The alternatives are as
follows:
Baseline - No regulation of NOx
Alternative 1 - Require NO control level achievable by application of
SNCR for MWC plants with capacities of 1,100 tons per day or greater.
No NO control would be required for plants smaller than 1,100 tons per
day.
Alternative 2 - Require NO control level achievable with SNCR for MWC
plants with capacities of 250 tons per day or greater. No NO control
would be required for plants smaller than 250 tons per day.
Alternative 3 - Require NO control level achievable with SNCR for MWC
plants of all sizes.
pmw/059b
appendix.c
C-7
-------
TABLE C-2. COST AND COST EFFECTIVENESS OF NO CONTROL FOR NEW MWC'S5
X
Model Plant
I.D. No. and Type
Cost
Model Plant Annual Cost of Annual Control Cost NO Emissions (tons/yr) Effectiveness
Capacity (tpd) NO Control ($l,000/yr) ($/ton HSU combusted) Baseline Controlled ($/ton NO )
1. MB/WW
2. MB/WW
3. MB/WW
4. MB/REF
5. MB/RC/WW
6. RDF
7. RDF6
8. HI/EA
9. MI/SA
10. MI/SA
11. FBC
12. FBC
200
800
2,250
500
1,050
2,000
2,000
240
50
100
900
900
279
582
1,140
549
680
1,159
1,097
337
190
248
658
658
6.70
2.20
1.50
3.30
1.90
1.70
1.60
4.20
18.30
11.90
2.20
2.20
72
463
1,302
290
607
1,425
1,263
139
18
58
602
602
40
254
716
159
334
784
695
77
9.9
32
331
331
8,570
2,790
1,950
4,210
2,490
1,810
1,930
5,400
23,300
9,530
2,4 30
2,430
*MB/ WU ¦ Mass burn/waterwall
MB/REF - Mass burn/refractory
MB/RC/WW - Mass burn/rotary combustor/vatervall
RDF ¦ Refuse~derlved fuel-fired
Hl/EA ¦ Modular lnclnerator/excess air
MI/SA - Modular Incinerator/starved air
FBC ¦ Fluldlzed-bed combustor
Coflred plant.
pmw/059b
app.a
-------
Figure C-2.
0.8 1.2 1.6
(Thousands)
PLANT SIZE (TONS/DAY)
Cost-effectiveness of NUx control vs model plant capacity.
-------
Model plant emission, cost, and cost effectiveness impacts of
Alternatives 1, 2, and 3 can be determined from Table C-2. For example,
Regulatory Alternative 1, which would require control of only those plants
above 1,100 tons per day, would result in model plant control costs of $1.50
to $1.70 per ton MSW combusted. Alternative 2, which would require control
of plants above 250 tons per day, would result in model plant control costs
of $1.50 to $3.30 per ton MSW combusted. Alternative 3, which would require
N0X control for MWC's of any size, would result in model plant control costs
of $1.50 to $18.30 per ton MSW. Costs are highest for the smallest model
pi ants.
Table C-3 shows the national impacts of N0X control. These were
calculated using the number and distribution of new MWC's shown in Table 4-1
and assuming all MWC's above the regulatory cutoff would apply SNCR controls.
Baseline N0X emissions are 32,400 tons/yr. Under Regulatory Alternatives 1,
2, and 3, N0X emission reductions are 9,430, 13,700, and 14,600 tons/yr,
respectively. Annualized social costs of NOx control range from $18
million/yr for Regulatory Alternative 1 to $37 million/yr for Alternative 3.
Table C-3 also shows the incremental costs (in $/ton MSW combusted) of each
regulatory alternative compared to the next less stringent alternative.
Incremental annual costs range from $1.80/ton MSW for Regulatory Alternative
1 over baseline to $6.50/ton for Alternative 3 over Alternative 2. These
costs would be in addition to baseline combustor costs and costs of the MWC
emissions regulatory alternatives described in Chapters 9 and 10.
The incremental cost effectiveness, expressed in terms of incremental
national costs per ton of N0X emission reductions, also increases across the
regulatory alternatives ranging from $l,900/ton N0X for Alternative 1 to
$8,350/ton for Alternative 3.
pmw/059b
appendix.c
C-10
-------
TABLE C-3. NATIONAL IMPACTS OF REGULATORY ALTERNATIVES
Alternative0
NO Emissions
ana (Emissions
Reductions)
(Tons/yr)
Annualized
Social Cost
($io6/yr)
Incremental
Annualized
Social Cost
per ton.MSW
(S/ton)
Incremental
Cost
Effectiveness
(S/ton NO .
reduction;
Baseline
32,400 (0)a
0
0
0
Alternative 1
23,000 (9,430)
18
1.80
1,900
Alternative 2
18,700 (13,700)
30
2.30
2,730
Alternative 3
17,800 (14,600)
37
6.50
8,350
aAnnual emissions are given, followed by emission reductions in parenthesis.
''incremental costs compare each alternative to the next less stringent
alternative.
NO standards would apply to the following MWC plants:
Baseline - no plants
Alternative I - plants larger than 1,100 tons/day capacity
Alternative II - plants larger than 250 tons/day capacity
Alternative III - all plants
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appendix.c
C-ll
-------
APPENDIX D. HYDROGEN CHLORIDE AND SULFUR DIOXIDE EMISSIONS DATA
D.1 INTRODUCTION AND SUMMARY
Sulfur dioxide (S05) and hydrogen chloride (HC1) emissions data from
^ *
two MWC's equipped with lime spray dryers were analyzed to determine the
relationship between the reduction in SO2 emissions achieved and the
reduction in HC1 emissions achieved. The analysis found that reductions in
SOg emissions are positively correlated with reductions in HC1 emissions and
that reductions in SO2 emissions can serve as a surrogate for reductions in
HC1 emissions. For example, based on these plants, achieving a reduction of
85 percent in SO2 emissions would lead to a reduction of 96 percent or more
in HC1 emissions.
The variability in SO2 emissions present in long term (i.e., 60 days)
continuous SO, emissions data gathered from a wel1-designed and
^ *
well-operated MWC equipped with a lime spray dryer was also analyzed to
determine the relationship between long term SOg emission control
performance and short-term SOg emission control performance. For the range
of performance levels considered, there is roughly a five percent difference
between long-term average percent SOg reduction and the expected minimum
24-hour percent reduction. For example, if the long-term average S02
emission reduction is 90 percent, the expected worst case or minimum 24-hour
average percent reduction in SO2 emissions is over 85 percent.
D.2 HYDROGEN CHLORIDE VERSUS SULFUR DIOXIDE EMISSIONS
Emissions data from two MWC's equipped with spray dryers were evaluated
to investigate relationships between HC1 and S02 removal behavior.7 The two
MWC's evaluated were the Mi 11 bury Resource Recovery Facility in Mi 11 bury,
Massachusetts and the Marion County Solid Waste-to-Energy Facility in
Brooks, Oregon. At the Millbury site, acid gases and particulate emissions
were removed from furnace flue gases by a spray dryer (using lime slurry
~
At one plant a SD/FF system was used, and at the other plant a SD/ESP
system was used.
pmw/059b
appendix.d
D-l
-------
injection) and an electrostatic precipitator. The air pollution control
system at Marion County consisted of a cyclone, lime slurry spray dryer, dry
venturi (injecting a proprietary sorbent), and fabric filter. Sixty days of
hourly emissions data were collected at the Mill bury facility. The Marion
County data consisted of 10 sets of characterization data; each was two to
three hours in duration (for a total of 27 hourly data points).
Theoretically, all other things being equal, HC1 should be
preferentially absorbed relative to SO2 in an acid gas control system. As a
result, acid gas control systems should achieve higher percentage reductions
in HC1 emissions than in SO2 emissions. This expectation was confirmed by
the Millbury and Marion County data.
Evaluation of the emissions data from both Millbury and Marion County
show the percentage reduction achieved in HC1 emissions is positively
correlated with the percentage reduction achieved in SO^ emissions. The
relationship between the percentage reduction in HC1 emissions and that in
SO2 emissions observed at Marion County, for example, is shown in
Figure D-l.
These data indicate that a requirement to achieve a specific percent
reduction in SOg emissions may be used as a surrogate to ensure that a high
percent reduction in HC1 emissions is also achieved. As shown in
Figure D-l, for example, achieving an 85 percent or higher reduction in SO^
emissions through acid gas control at Marion County would result in
achieving a 96 percent or higher reduction in HC1 emissions.
D.3 SULFUR DIOXIDE EMISSIONS VARIABILITY
An assessment of the variability in SO2 emissions present in the long
term 60-day continuous emission data gathered at Millbury was also
undertaken to examine the relationship between the long term emission
control performance of the control system at Millbury and the expected worst
case short-term emission control performance. Given the variability
observed in SO2 emissions over this 60-day period, one should expect to
observe emission control performance over short time periods that is both
better and poorer than the long-term mean or average performance observed
over the 60-day period.
pmw/059b
appendix.d
D-2
-------
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
MWC Data Analysis - HCI vs S02
Marion County - Test Run Average
Percent Reduction S02
Figure D-l. HCI percent reduction vs. SO,, percent reduction
-------
In other words, given the variability in SOj emissions that is expected
during normal operation of a well-designed and wel1-operated lime spray
dryer system, there will be short periods of time that will occur during
which the system exhibits poorer performance than the system achieves over
the long term. Consequently, emission limits included in NSPS and emission
guidelines need to be established at levels able to accommodate these short
term variations in performance that are expected to occur.
The long-term mean or average percent reduction achieved in S02
emissions at Millbury was 78 percent and the long-term mean or average SC^
emission level achieved was 37 ppm, corrected to 7 percent oxygen. Assuming
the SO2 emission variability present in the Millbury data is representative
of the long-term performance of this emission control system, the expected
worst case or minimum 24-hour average percent reduction in SO^ emissions is
71 percent. In order words, if SO2 emissions are measured continuously, a
minimum 24-hour average percent reduction of 71 percent is entirely
consistent with achieving a long-term mean or average percent reduction of
78 percent.
Spray dryer/FF systems can achieve higher performance levels than those
measured at Millbury. Based on the variability encountered in the Millbury
data, a long-term average SO2 emission reduction of 90 percent would equate
to over 85 percent reduction on a 24-hour average basis.
pmw/059b
appendix.d
D-4
-------
APPENDIX E. TOXIC EQUIVALENCY CORRELATIONS AND TOTAL DIOXINS/FURANS
E.l INTRODUCTION AND SUMMARY
There are various measures of CDD/CDF emissions that could be specified
in a regulation. Possibilities include total tetra- through octa-CDD/CDF,
2,3,7,8-TCDD toxic equivalents, or specific homologues. As part of an
assessment of CDD/CDF emissions from MWC's and the impact of various
emission control techniques on emission reductions, available data were
examined to determine the most appropriate measure for CDD/CDF
8 9
emissions. '
The homologue distributions and the contribution of. specific homol'ogue
groups to total 2,3,7,8-TCDD toxic equivalency were analyzed to identify the
best surrogate for total 2,3,7,8-TCDD toxic equivalents. The finding of
these analyses were that total tetra- through octa-CDD/CDF correlates well
with toxic equivalency. Therefore, total tetra- through octa-CDD/CDF has
been used in analysis of all dioxin/furan data, and this is an appropriate
measure of CDD/CDF emissions to use in setting an emission limit for CDD/CDF
emissions from MWC units.
E.2 CORRELATIONS
The CDD and CDF homologue distributions were evaluated for 21
facilities; 9 of these had uncontrolled data, 18 had controlled emissions
data, and 5 had simultaneous uncontrolled and controlled data.
Correlations between 2,3,7,8-TCDD toxic equivalents and total tetra-
through octa-CDD/CDF yielded a correlation coefficient of 0.9212 [(R^)
between total tetra- through octa-CDD/CDF and toxic equivalents]. Using
this correlation, toxic equivalency can be estimated from total tetra-
through octa-CDD/CDF using the equation:
toxic equivalency = 0.0152 x (total tetra- through octa-CDD/CDF).
pmw/059b
Appendix.E
E-l
-------
APPENDIX F. MATERIALS SEPARATION
F.l INTRODUCTION AND SUMMARY
This appendix discusses the potential benefits of prohibiting
combustion of certain materials in MWC's as part of the Section 111
standards and emission guidelines. This appendix briefly summarizes
information on current materials separation and recycling programs, the
feasibility of separating materials from the waste stream, the potential
impacts of materials separation on air pollutant emissions from MWC's, and
other potential impacts associated with materials separation. The
alternative of not requiring materials separation under Section 111 as well
as three other regulatory alternatives for new MWC's are described.
Standards and emission guidelines under Section 111 cannot require
recycling and reuse of certain materials; they could, however, prohibit
combustion of specific materials in MWC units, thus resulting in separation
of these materials from municipal waste. This may encourage recycling.
Currently, there are limited data concerning the impacts of waste separation
on MWC emissions. Separation of non-combustibles, which include lead-acid
batteries and other materials containing heavy metals, appears to result in
lower emissions of heavy metals such as lead, mercury, and cadmium. On the
other hand, separation of certain materials, such as polyvinyl chloride
(PVC) plastic, does not appear to result in significantly lower emissions of
CDD/CDF. This is probably because there are numerous sources of CDD/CDF
precursors in waste in addition to plastics. It would appear, however, a
rather logical and straight-forward conclusion that removing certain
materials from MSW would result in lower air pollutant emissions of these
materials from combustion; and, in fact,.none of the limited data which are
available indicates that removing specific materials results in increased
emissions.
As mentioned above, although Section 111 regulations could require
materials separation, they could not dictate how the separated waste would
be disposed of (i.e., recycling, landfilling, roadside dumping, etc.). In
many cases there are limited markets for recycled materials. This is a key
factor. Without a local market in place, MSW separation costs could be as
pmw/059b
Appendix.F
F-l
-------
high as S6/ton MSW and approach the cost of SD/FF control at a large new MWC
(about $8/ton MSW). With good local markets for separated materials,
separation costs can be offset, resulting in negligible overall costs. The
ultimate impacts associated with materials separation, therefore, are very
unclear. Furthermore, the Agency is currently considering use of other
regulatory authorities, such as the Toxic Substances Control Act, to require
separation and proper disposal of materials containing lead and cadmium.
Given the fact that Section 111 standards could only address a small
part of the Agency's overall materials separation and recycling goal, that
other regulatory authorities may more broadly address disposal, and that
further studies and planning activities are underway, it may be premature
for the air emission standards to require material separation at this time.
Without an established market, MSW separation may be prone to failure.
However, as explained in Section F.5, three materials separation regulatory
alternatives are under consideration.
F.2 CURRENT TRENOS IN MATERIALS SEPARATION AND RECYCLING
Currently in the U.S., recycling (which includes separation of a
material from the waste stream, collection, processing, and reuse of the
material) is used to manage about 10 percent of total solid wasted0
Additional materials may be separated and disposed of rather than recycled,
however, the extent to which this may occur has not been quantified.
The Agency's overall strategy for dealing with thp many problems
presented by municipal solid waste, "An Agenda for Action", proposes to
reduce the total MSW stream by 25 percent through recycling and source
reduction by 1992.*® To accomplish this goal, the Agency plans to develop
technical guidance and educational materials, facilitate information flow,
assist in research and development, increase federal purchasing of recycled
or recyclable materials, and assist States in planning waste reduction
strategies. Since one third of all U.S. landfills are projected to be full
by 1993, many States, counties, and municipalities are looking towards
recycling as a means of extending landfill life.*® Some States are
developing regulations or have passed legislation to require materials
separation and encourage recycling.
pmw/059b
Appendix.F
F-2
-------
Materials presently recycled in the U.S. are newspaper, office paper,
cardboard, mixed paper, ferrous metals, aluminum, glass, polyethylene
terephthalate (PET) plastic soft drink containers, lead-acid batteries, yard
waste (compost), and to a much lesser extent automobile tires, other
plastics, used oil, and other batteries.
F.3 MATERIALS SEPARATION METHODS
Separation of materials from MSW is accomplished in two ways: source
separation and centralized separation. Source separation is defined as the
separation of materials from the waste by the generator; it is presently the
primary method of separation in the U.S. At the household level, source
separation is accomplished by placing waste items (e.g., glass, paper,
aluminum, etc.) in segregated containers for curbside pick-up or by
separation and transportation to local recycling bins or buy-back centers.
Source separation is also practiced by commercial establishments.
A lesser amount of waste separation is accomplished at centralized
separation facili-ties. There are 30 to 40 centralized waste separation
facilities operating in the U.S. These facilities use manual as well as a
wide variety of mechanical technologies to achieve waste separation. Often
these facilities operate in conjunction with refuse-derived fuel-fired (RDF)
combustion plants to produce a more uniform fuel with many of the
non-combustibles removed for subsequent landfilling or recycling. Some of
the more advanced facilities can produce saleable products such as ferrous
scrap, aluminum scrap, glass cullet, baled cardboard or paper, and compost.
F.4 IMPACT OF MATERIALS SEPARATION OF MWC EMISSIONS
The following sections discuss available information on the effects of
materials separation on MWC air emissions. Particular air pollutants of
concern are metals, organics including CDD/CDF, and acid gases including
HC1.
Non-combustibles. Non-combustible materials such as aluminum, glass,
and ferrous metals do not directly produce potentially hazardous emissions.
However, some ferrous items contain lead-soldered components such as steel
cans, which are sources of lead in MSW. Batteries, particularly automobile
batteries, are also major sources of heavy metals.
pmw/059b
Appendix.F
F-3
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Studies at three existing mass bum combustion facilities showed that
emissions of lead, mercury, and cadmium were reduced by about 50 percent
when non-combustibles were removed prior to incineration. In these studies,
the waste was sorted by a mechanical process using combinations of cutters,
magnets, eddy current separators, and air separation systems to produce four
waste fractions: ferrous metals, nonferrous metals, glass/grit, and fuel
(paper, plastic, etc.). Lead acid batteries, however, were removed by
hud .»•"
Household Batteries. Many household batteries are composed of high
amounts of toxic heavy metals such as mercury and cadmium. Batteries could
be a significant source of toxic metals from MWC's burning unprocessed
waste. There are no data available, however, to indicate what impact
removal of household batteries from MSW would have on emissions of toxic
metals from combustion of MSW. In addition, there are no data available
indicating what proportion of the total amount of toxic metals, such as
mercury, in MSW is due to household batteries. Thus, it is not possible to
draw conclusions regarding the impact on emissions of removing household
batteries from MSW.
Mercury is found in several types of batteries. However, due to the
adverse environmental and health effects of mercury and the economics of
mercury in battery manufacturing, the use of mercury in battery production
is declining. Thus, their disposal in MWC's will decrease even if materials
separation is not required.^
Cadmium is also a toxic metal of concern in the disposal of batteries.
Nickel-cadmium batteries are probably the primary source of cadmium in MSW,
and it is likely that removing them from MSW would result in lower emissions
of cadmium from combustion of MSW, although, there are no data directly
measuring effects of removing these batteries on emissions. Of much greater
significance, however, is the fact that it is quite difficult to separate
household batteries from MSW since most nickel-cadmium batteries are
permanently encased in the products they power.^
Lead-acid Batteries. Lead-acid (automotive) batteries are the single
most prevalent source of lead in MSW. One study showed that lead-acid
9
batteries comprised over half of the total lead content of unsorted MSW.
pmw/059b
Appendix.F
F-4
-------
Based on this information, removal of lead-acid batteries should
significantly reduce lead emissions from MWC's, although, there are no data
showing lead emission reduction from removal of lead-acid batteries alone.
Of much more concern, however, is the fact that recycling of lead-acid
batteries has decreased from over 97 percent in the mid-I960's to about 70
percent in 1985. The decline is attributed to the increased cost to
recyclers for compliance with occupational health and environmental
regulations and to the decreased cost of lead.13"1^
Traditionally, lead-acid batteries have been returned to retailers for
trade-in or dropped off at service stations; however, many such facilities
now refuse to accept them. At this point, it is uncertain whether requiring
materials separation of lead-acid batteries would result in increased
recycling. Rather than result in increased recycling, separation
requirements could result in increased landfill disposal of lead-acid
batteries and/or an increase in "roadside" dumping. In most cases, if
batteries were separated at the MWC, they would probably be sent to a
landfill for disposal. However, in some cases, for example if a hauler
refused to pick up batteries from households, individuals might directly
dump batteries.
Polyvinyl Chlorides. Polyvinyl chloride (PVC) is a chlorine source and
has been shown to be a precursor for formation of CDD/COF in laboratory
tests, but its" role in C00/C0F emissions from MWC's is not clear. One
recent study showed that removal of PVC did not significantly affect CDO/CDF
emissions from MWC's.16 It is believed that CDD/COF precursors are diverse
in the MSW stream and are an incomplete combustion product, so.separation of
PVC is not likely to significantly reduce emissions of CDD/CDF. Separation
of PVC may help reduce HC1 emissions, but not to a level sufficient to limit
chlorine availability for CDD/CDF formation.16 Very little PVC is currently
separated and recycled.
Paper. Paper products comprise the largest segment of MSW and are the
primary combustion source in the incineration of MSW. If a high proportion
of paper were removed, the heating value of the MSW fuel would be less, and
combustion performance could decline, possibly resulting in higher emissions
pmw/059b
Appendix.F
F-5
-------
of some pollutants. n the other hand, paper removal might reduce emissions
of other pollutants. Paper products, especially bleached paper, are sources
of chlorine, but it is not clear to what extent paper recycling would effect
HC1 emissions since chlorine is distributed throughout the combustible waste
fraction. Paper products are also potential sources of chromium, lead, and
cadmium since they are often imprinted with inks containing high
concentrations of these metals. Separation of some paper may help to reduce
heavy metal emissions, but these metals are also found in many other
portions of the combustible and non-combustible wastes. No data are
available on effects of paper separation on MWC emissions. While corrugated
paper, paperboard, newspaper, office paper, computer printout, and some
other types of paper are suitable for recycling, many other types of paper,
such as those contaminated with food residue or adhesive coatings, are
undesirable for recycling. As with other materials, separation requirements
for paper would not necessarily lead to increased recycling, but could
result instead in greater burdens for landfills or increased roadside
1itter.
Yard Wastes. Yard waste (leaves, grass clippings, and brush) is the
second most prevalent constituent of MSW.^ Because of its highly variable
moisture content, yard waste exhibits inconsistent combustibility which may
hinder combustion performance and potentially contribute to products of poor
combustion.^ There are no data relating removal of yard waste to
emissions. Composting is one alternative for managing yard wastes; however,
requirements to separate and exclude yard waste from MWC's could not ensure
increased composting. Much of the yard waste diverted from the combustion
process might be landfilled, therefore, reducing the life of many landfills.
F.5 MATERIALS SEPARATION REGULATORY ALTERNATIVES
Four NSPS regulatory alternatives were considered for control of MWC
emissions through materials separation. These are described below:
Baseline - No materials separation required
Alternative 1 - Require new MWC's to complete a study of materials
separation and recycling feasibility as part of their
permitting process. This would encourage separation
and recycling, but would allow site-specific factors to
pmw/059b
Appendix.F
F-6
-------
determine whether and how to implement materials
separation and/or recycling programs.
Alternative 2 - Ban combustion of lead-acid batteries (and possibly TV
sets or other selected items). This would reduce lead
emissions. However, there are enforcement
difficulties. Section 111 standards would only apply to
owners or operators of MWC's and could not -equire
community source separation programs. In order to
locate and separate batteries at the MWC, substantial
modifications to the MWC handling process at MWC plants
would be needed.
Alternative 3 - Require removal of non-combustibles prior to combustion.
This would reduce emissions of lead, cadmium, mercury,
and other metals. By definition, RDF plants already
meet this alternative. Mass burn and modular MWC's
would be required to install systems to separate
non-combustibles, as described under Sections F.3 and
F.4 "Non-combustibles".
Table F-l provides rough estimates of the metals reductions achieved by
the regulatory alternatives for new mass burn and modular MWC's. Mass
emissions of metals are highly variable among MWC's, so emission impacts are
expressed in terms of percent reductions. While total metal reductions of
up to 50 percent can be achieved through materials separation, the ESP or FF
systems required by all of the MWC emission regulatory alternatives (see
Sections 5.0 and 8.0) already achieve over 97 percent control of all metals
(except mercury) relative to uncontrolled emissions. Therefore, only an
additional 2 percent reduction can be achieved by materials separation.
This would have a relatively small incremental effect (e.g. from 97 percent
total metals control with an ESP to about 99 percent control with an ESP
plus separation of non-combustibles).
Table F-2 shows the national annual cost of control for the regulatory
alternatives and a range of model plant costs based on two model new
facilities, one 400 tpd and one 1680 tpd facility. Costs of Regulatory
Alternative 1 (requiring new MWC's to perform studies) would be negligible.
Individual plant costs for Regulatory Alternative 2 range from $1.25/ton MSW
combusted for the large model plant to $2.90/ton MSW for the small model
plant. The total national annual cost of Alternative 2 is $29 million. The
incremental cost per ton MSW of Regulatory Alternative 2 compared to
Alternative 1 or baseline is SI.80. These costs are based on loading MSW
pmw/059b
Appendix.F
F-7
-------
TABLE F-l. EMISSION IMPACTS OF REGULATORY ALTERNATIVES REQUIRING
MATERIALS SEPARATION
% Total metals control
relative to uncontrolled
Alternative emissions
MWC with ESP or DSI/ESP
control system (or with
SD/FF control system)
97% (99%)a
No-control alternative
(same control as above)
97% (99%)
Alternative 1
>97% (>99%)b
Alternative 2
>97% (>99%)c
Alternative 3
99% (>99%)
First number is for ESP or DSI/ESP control. Numbers in ( ) are for SD/FF
control systems. Percent reductions apply to sum of all metals emissions.
Over 97 percent control is achieved for all individual metals except
mercury.
^Emission impact of this alternative is unknown. It would encourage, but
not require materials separation.
°Emission impact of this alternative is unknown. It would achieve some
additional metals reduction, particularly lead, but there have been no
controlled studies to provide emissions reduction data.
pmw/059b
Appendix.F
F-8
-------
TABLE F-2. COSTS OF REGULATORY ALTERNATIVES REQUIRING MATERIALS SEPARATION
FOR NEW MWC'S
Alternative
National Cost
(S106/yr)
National
Incremental
Cost per tog
MSW (S/ton)
Range of Model
Plant Cost per
ton MSW (S/ton)
1
Negligible
Negligible
Negligible
2
29
1.80°
1.25 - 2.90°
3
92
3.80d
[Negligible]
5.50 - 5.90da
[Negligible]
incremental costs compare each alternative to the next less stringent
alternative.
Model plant cost ranges are based upon costs at a 400 tpd facility and a
1680 tpd facility. Plants with capacities smaller or larger than this may
experience costs outside this range. These costs are not incremental.
°The credit for recycling automative batteries (Alternative 2) is negligible
since automotive batteries comprise a very small proportion of total MSW.
dThese costs do not include credits for sale of separated materials. They
are representative of costs where local markets for separated materials do
not exist and separated material is landfilled.
eFor Alternative 3, if there are local markets, potential revenues for
recycling non-combustibles may range from about $2.25 to about S6.50/ton
MSW processed depending on the efficiency of the separation equipment and
the market price of the non-combustible materials. An additional credit of
about 55.00/ton MSW processed can be achieved from avoided landfill cost
since the recyclable materials are diverted from the landfill. It these
credits are assumed, the cost of Alternative 3 Is neglible.
pmw/Q59b
Appendix.F
F-9
-------
received at the MWC onto a conveyor system with visual inspection and hand
removal of lead-acid batteries.
Control costs of Alternative 3 range from S5.50 to S5.90/ton MSW for
the model plants. However, the cost of Alternative 3 may be offset by
potential credits such as sales of recyclables (about S2.25 to S6.50/ton MSW
processed depending on market prices for recoverable materials) and avoided
landfill cost (about $5.00/ton MSW processed). Thus, for some plants where
local markets are favorable the cost of Alternative 3 would be negligible.
For others, where markets are poor, separated materials may not be sold, and
may have to be landfilled. In these cases, costs would not be offset by
credits. Assuming no credits, the total national annual cost of Alternative
3 is S92 million, and the incremental cost per ton MSW of Alternative 3
compared to Alternative 2 is S3.80. Cost estimates for Alternative 3 are
based on vendor-supplied costs of systems to remove non-combustibles.
pmw/059b
Appendix.F
F -10
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APPENDIX G. ASH
G.l INTRODUCTION ANO SUMMARY
Combustion of MSW produces two types of ash: fly ash, which is the
fine particulate material collected by air pollution control equipment; and
bottom ash, which is collected in the combustor. Most MWC facilities in the
U.S. physically combine the fly ash and bottom ash to produce a single waste
stream. A primary concern with handling and disposing of MWC ash is whether
toxic contaminants in the ash will leach and migrate to groundwater
supplies. Because concentrations of CDD/CDF are generally very low and
CDO/CDF are relatively insoluble, the concern with MWC ash has been the
possible leaching of the heavy metals; principally lead (Pb) and cadmium
(Cd).
Draft guidelines for MWC ash disposal have been developed by OSW, and
similar disposal requirements would be mandated by House Bill 4357, known as
the luken bill, which will be reintroduced in the next session of Congress.
The recommended disposal guidelines and the Luken bill would protect
groundwater from contamination by leachate from MWC ash disposal sites, and
are comparable in stringency to RCRA Subtitle C hazardous waste landfill
requirements. The Luken bill would require that ash be disposed of in (1) a
~
single composite-lined monofill (a landfill that accepts only MWC ash) with
groundwater monitoring and leachate collection systems, or (2) a double
composite-lined landfill with groundwater monitoring and leachate collection
systems if the ash 1s co-disposed with MSW. Under the Luken bill, disposal
1n a permitted sanitary landfill (which would meet applicable RCRA Subtitle
D regulations) might also be allowed if the ash can meet new testing
procedures to be developed by EPA.
Some of the Section 111 regulatory alternatives for MWC's would require
acid gas control. The addition of lime scrubber solids, including unreacted
lime and alkaline earth salts, to the MWC ash would alter the pH and
chemical characteristics of the waste ash mixture, which could change the
solubility or Teachability of the ash. Therefore, available data were
*A composite liner consists of a flexible membrane liner over a compacted,
low permeability soil layer.
pmw/059b
appendix.g
G-l
-------
reviewed to determine whether addition of lime will increase the solubility
18
and rate of leaching of heavy metals. This analysis is summarized in the
discussions that follow.
The general conclusions of the analysis are: (1) the addition of lime
scrubber solids to MWC ash may increase the leachability of some metals
(particulary Pb) in a monofill environment, but might decrease leachibility
of other metals; and (2) it is unlikely that leachability would be increased
in a co-disposal environment. The data, however, are limited and somewhat
contradictory. Whether requirements for acid gas controls increase or
decrease the leachability of metals, the draft OSW guidelines and the Luken
bill would require disposal of MWC ash in landfills designed with controls
to contain leachate. Consequently, there is little likelihood of
18
groundwater impact arising from control of acid gas emissions from MWC's.
G.2 OATA SUMMARY
Few data on leaching of metals from MWC ash are available. Common test
procedures for identifying which wastes pose hazards due to their leaching
potential are the extraction procedure (EP) toxicity test and the toxicity
characteristic leaching procedure (TCLP). The EP and TCLP were designed to
simulate the weakly acidic environment generally found in sanitary landfills
or co-disposal sites, which typically produce leachate with a pH of
about 5.0. These tests may not accurately simulate leaching from MWC ash
monofills, since addition of lime scrubber solids including unreacted lime
to MWC ash may raise the pH to a range of 11 to 12.5.
Tests performed where ash was extracted with water to simulate a
monofill disposal environment have shown that Pb solubility in the ash can
be increased by approximately 8-fold where pH values exceed 12. This
increased solubility may be attributed to the complexation of Pb with
chloride and hydroxide to form soluble anions in the aqueous solution
associated with the ash. No data using water extraction are available for
Cd.
Consideration of these data and theoretical chemical processes
indicates that addition of lime to MWC ash may increase the solubility of
Pb, and possibly Cd in a monofill facility exposed to natural precipitation.
The degree of solubility would depend on the levels of Pb and Cd in the ash
pmw/059b
appendix.g
G-2
-------
as well as the relative amounts of lime, chloride, and sulfate in the
scrubber solids. All of these characteristics are site-specific and highly
vari able.
Available data indicate that addition of lime scrubber solids to ash
disposed in a co-disposal environment, however, is not likely to increase
leaching.of metals since the pH of leachate is much lower than in a
monofill. The leachability would depend on the amount of lime added and the
amounts and characteristics of waste co-disposed with the MWC ash. The EP
and TCLP tests are designed to simulate a pH of 5 which is typical of
co-disposal sites. If excess lime is present in waste, the pH of the
extracting solution would rise above 5, and Pb and Cd solubility could be
lowered. (The solubility curves of Pb and Cd compounds show reduced
solubility at near neutral pH's [i.e., pH near 7] and increased solubility
at low or high pH values.) Thus, the addition of lime scrubber solids could
reduce solubility and cause MWC ash that previously failed the EP and TCLP
tests to pass these tests. One study showed that Pb and Cd in MWC ash were
lowered to nonhaz'ardous levels by increasing the alkalinity through addition
of scrubber solids and cement.
Due to the limited amount of data on solubility of metals from MWC ash
to which lime scrubber solids have been added as well as the variation in
MWC ash characteristics and disposal environments, no firm conclusions can
be drawn on whether addition of lime scrubber solids will typically increase
leaching of metals within landfills. In any case, the draft OSW guidelines,
the Luken bill and proposed Subtitle 0 regulations would require disposal of
MWC ash in landfills designed with controls to contain leachate and prevent
water pollution problems.
pmw/059b
appendix.g
6-3
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APPENDIX H. MWC RISK ASSESSMENT
H.1 INTRODUCTION AND SUMMARY
A risk assessment was conducted in 1987 as part of the supporting
information for the decision to regulate MWC's under Section 111 of the CAA.
Ranges of results were published in the July 7, 1987, advanced notice of
proposed rulemaking (ANPRM). A new risk assessment, incorporating more
information on the numbers and types of MWC's and their emission
characteristics, was conducted in 1988 and 1989 during development of the
NSPS and emission guidelines.
The new risk assessment estimated baseline annual cancer incidence from
new MWC's subject to the NSPS to be about 1 to 10 cases/yr. Annual incidence
for existing MWC's (those commencing construction by 1989) was estimated to
be 1 to 30 cases/yr. The majority of the risks are associated with metals
emissions, although organics (including CDD/CDF) also contribute to the
risks. These risk ranges account for uncertainty in the emission estimates
and include cancer'risks from direct inhalation of ten pollutants or
pollutant groups in MWC emissions, risks from additional unspeciated
pollutants, and risks from indirect exposure pathways. The risks are at the
lower end of the ranges estimated in the 1987 analysis even though the 1987
ranges did not include indirect exposure or unspeciated pollutants.
The new analysis estimates a maximum individual risk (MIR) for new MWC's
of about ID*5 at baseline. The baseline MIR for existing plants approaches
-4
10 . The baseline MIR's for new and existing MWC's are within the middle of
the ranges previously projected. Thus, the new analysis supports the
previous decision to regulate MWC's under Section 111.
H.2 RISK ASSESSMENT METHODOLOGY AND RESULTS
The public health risks due to exposure from direct inhalation of
emissions of arsenic, beryllium, cadmium, hexavalent chromium, lead, mercury,
CDD/CDF, chlorobenzenes, chlorophenols, formaldehyde, polycyclic aromatic
hydrocarbons, polychlorinated biphenyls, and HC1 from new and existing MWC
plants were estimated. The carcinogenic effects were assessed for exposure
to all of these pollutants except lead, mercury, and HC1 for which non-
carcinogenic effects were assessed. The comparison of ambient lead, mercury,
pmw/Q59b
appendix.h
H-1
-------
and HC1 exposure levels with health reference levels for noncarcinogenic
health effects is described in Sections 9.1.2 and 10.1.2 for new and existing
MWC's, respectively. Cancer risks are described below.
Annual Incidence. In order to estimate annual cancer incidence for new
and existing MWC's, a model plant approach was used. The 12 new (111(b))
model plants and 17 existing (111(d)) plants are the same as those used in
the emission, cost, and economic analyses for the NSPS and guidelines. The
models were designed to represent several different subcategories of new and
existing MWC's. Emission rates were selected based on all available emission
data for each subcategory of MWC's, including additional data not available
at the time of the 1987 risk assessment. These models were located in cities
in counties with average population density for the subcategory of MWC's they
represent. The Human Exposure Model (HEM) was used to estimate direct risks
to the exposed population. Results were scaled up to a national basis.
It should be noted that with this and all risk analyses, there are
significant uncertainties. These include uncertainties in the emission
estimates for the model plants, the population exposed, the dispersion
modeling, and the health risks resulting from a given exposure as estimated
using the unit risk factors. Figure H-l shows the variability of the
parameters used in annual incidence calculations. The figure shows that the
uncertainties could result in the annual incidence being either over- or
under-estimated. The point estimates of annual incidence from direct
inhalation of carcinogenic pollutants were converted to ranges in order to
account for some of these uncertainties. The range presented accounts for
(1) uncertainties in the emission estimates, (2) risks from other unspeciated
pollutants, and (3) risks from indirect exposure pathways. Health impacts
from indirect exposure to long-term deposited emissions may be comparable in
magnitude to direct inhalation risks. The other uncertainties shown in
Figure H-l are not included in the ranges.
The results of the annual incidence calculations for new and existing
plants are shown in Table H-l. For comparison, this table also shows the
results of the previous 1987 risk analysis published in the ANPRM. The risks
for the new analysis are toward the low end of the ranges presented in the
pmw/059b
appendix.h
H-2
-------
Probable Impact of Major Assumptions on MWC Cancer Risk
Assessment-Annual Incidence-Model Plant
(Orders of Magnitude)
EPA Estimate
UNIT RISK
ESTIMATE
EMISSIONS &
SOURCE
PARAMETERS
DISPERSION
MODEL
EXPOSURE
ASSESSMENT
Combined UREs
Other D/R models & data
Unidentified
compounds
Indirect Exposure
Synergism/Antagonism
Bioavailability
Emission Factor
Effect. Stack Ht.
Plant Life
Complex Terrain
Urban Release
HEM Meteorology
Plant Property
Expo not at Resid
Indoor-Outdoor
Migration
Human Activity
Urban/Rural Met
Lat/Long Urban
Lat/Long Rural
Emis fm Pit Ctr
Figure H-l. Probable impact of major assumptions on annual incidence estimate,
H-3
-------
TABLE H-l. BASELINE NATIONAL CANCER RISKS FOR 111(b) AND 111(d) PLANTS
Annual Maximum
Cancer Incidence Individual
(Cases/Year) Risk
Current Risk Assessment:
New (111(b)) plants 1 to 10 10~5
Existing (111(d)) plants 1 to 30 10"*
1987 Risk Assessment:
New plants 2 to 20 10"6 to 10"4
Existing plants 2 to 40 10"® to 10"3
pmw/059b
appendix.h
H-4
-------
previous analysis even though the 1987 risk ranges did not include indirect
risks or risks from unspeciated pollutants. The proportion of risks
accounted for by metals versus organics is greater for the new risk analysis.
Maximum Individual Risk. The HEM model was also used to calculate
maximum individual risks (MIR) for the 12 new and 17 existing model plants.
The resulting MIR values for new and existing MWC's are also shown in
Table H-l. Figure H-2 shows the variability of the parameters used in the
MIR analysis. Again, the Figure indicates that MIR may be over- or
under-estimated. The MIR represents the increased lifetime probability of
cancer (due to exposure to the combination of pollutants considered) for the
most exposed individual. The value given in the table for new plants
(10~^, or 1 in 100,000) is the highest MIR for any of the model plants.
Because of concern that the 17 model existing plants used for the annual
incidence analysis might not represent the "worst case" for some of the older
existing plants, four additional actual "reasonable worst case" plants were
-4
modeled to estimate MIR. The MIR approaching 10 (or 1 in 10,000) for the
actual large mass burn refractory and large RDF plants is the highest MIR
calculated. The MIR's only represent inhalation risks, and do not include
the potential impacts of unspeciated pollutants or indirect exposure.
The MIR's estimated in the previous 1987 risk assessment are also shown
in Table H-l. These MIR's also represent only inhalation exposure.
Comparison shows that the estimated MIR's for new and existing plants are
within the ranges given in the previous analysis.
pmw/059b
appendix.h
H-5
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Probable Impact of Major Assumptions on MWC Cancer Risk
Assessment-MIR-Model Plant
(Orders of Magnitude)
•2 EPA Estimate +1 +2
Combined UREs
Other D/R models & data
Unidentified
compounds
Indirect Exposure
Synergism/Antagonism
Bioavailability
UNIT RISK
ESTIMATE
EMISSIONS &
SOURCE
PARAMETERS
DISPERSION
MODEL
Emission Factor
Effect. Stack Ht.
Plant Life
Complex Terrain
Urban Release
EXPOSURE
ASSESSMENT
HEM Meteorology
Plant Property
Expo not at Resid
Indoor-Outdoor
Migration
Human Activity
Urban/Rural Met
Lat/Long Urban
Lat/Long Rural
Emis fm Pit Ctr
Figure H-2. Probable impact of major assumptions on MIR estimate.
H-6
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APPENDIX I. REFERENCES FOR APPENDICES A-H
1. American Society of Mechanical Engineers. Proposed ASME Standard for
the Qualification and Certification of Resource Recovery Facility
Operators (Draft). New York, New York. October 1988.
2. Memorandum. Vancil, Michael A., and David M. White, Radian
Corporation, to Walt Stevenson, EPA/SDB. Emission of Nitrogen Oxides
from Municipal Waste Combustors. October 6, 1988. 14 pp.
3. Telephone Conversation. Vancil, Michael A. (Radian Corporation) with
Tripp, Charles (SERRF Operations Officer). January 26, 1989.
4. Telephone Conversation. Vancil, Michael A., (Radian Corporation) with
Reeves, Gary (Stanislaus County APCD). January 19, 1989.
5. Conversation. White, David M. (Radian Corporation) with Licata,
Anthony (DRAVO). April 12, 1989.
6. Radian Corporation. Control of NO Emissions from Municipal Waste
Combustors. (Prepared for U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina). February 3, 1989. pp. 4-1 to
4-18, 5-1 to 5-25.
7. Memorandum. Aul, E. F., and C.W. Stackhouse, Radian Corporation, to
A.E. Vervaert, EPA/ISB. Analysis of Hydrogen Chloride and Sulfur
Oloxide Emissions from Two Municipal Waste Combustors Equipped with
Spray Dryers, Draft. January 27, 1989.
8. Memorandum. Vancil, Michael, A., Radian Corporation, to Mike Johnston,
EPA/ISB. Dioxin "Fingerprint" and 2,3,7,8-TCDD Toxic Equivalency
Analysis. February 3, 1988.
9. Memorandum. Vancil, Michael, A., Radian Corporation, to-Walt
Stevenson, EPA/SDB, and Mike Johnston, EPA/ISB. 2,3,7,8-TCDD Toxic
Equivalency Correlations. August 9, 1988.
10. U.S. Environmental Protection Agency. The Solid Waste Dilemma: An
Agenda for Action, Draft Report. Washington, DC, September 1988.
pp.2-14.
11. Sommer, E. J. (National Recovery Technologies, Inc.). Effects of MSW
Processing on Thermal Conversion of MSW in Mass Burn Incineration.
(Prepared for U.S. Department of Energy). December 31, 1987.
12. Telephone Conversation. Davis, A. Lee (Radian Corporation) with
Sommer, E. J. Jr., (National Recovery Technologies, Inc.).
November 3, 1987.
pmw/059b
Appendix.I
1-1
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13. U.S. Environmental Protection Agency. The Solid Waste Dilemma: An
Agenda for Action, Background Document, Draft Report. Washington, DC,
September 1988. pp. AF-1 to AF-20.
14. Telephone Conversation. Davis, A. Lee (Radian Corporation) with Sousa,
Mani (Interstate Lead, Inc.). December 27, 1988.
15. Telephone Conversation. Davis, A. Lee (Radian Corporation) with Price,
Betty (RSR, Inc.). December 29, 1988.
16. Midwest Research Institute. Results of the Combustion and Emission
Research Project at the Vicon Incinerator Facility in Pittsfield, MA.
(Prepared for New York State Energy Research and Development
Authority). June 1987.
17. Radian Corporation. Municipal Waste Combustion Study: Recycling of
Solid Waste. (Prepared for U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina). June 1987. pp. 1-2.
18. Memorandum. Epner, Eric, Danny Jackson, and Ruth Mead, Radian
Corporation, to MWC NSPS Project File. Assessment of
the Effects of Acid Gas Control on the Toxicity of Municipal Waste
Combustor (MWC) Ash. January 13, 1989.
pmw/059b
Appendix.I
1-2
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