Number range CHAPTER**Appendix D**

**Emission Estimation Procedures for State Plan**

**Emissions Inventory**

**Emission Estimation Procedures for State Plan**

**Emissions Inventory**

The pollutants emitted from municipal solid waste (MSW) landfills
include methane, carbon dioxide and non-methane organic compounds. The
attached chapter from the EPA document \"Compilation of Air Pollution
Emission Factors (AP-42)\"^1^ contains emission estimation procedures
and default values that can be used to calculate methane, carbon
dioxide, and NMOC emissions for MSW landfill emissions inventories and
other purposes. Emissions are calculated using equations (which are
based on a first order decomposition model), as a function of three
variables: the NMOC concentration in landfill gas (C~NMOC~), the methane
generation rate constant (k); and the refuse methane generation
potential (L~o~). The default values for these variables presented in
AP-42 are designed to provide typical, or average, estimates of MSW
landfill emissions and are appropriate for use in state emission
inventories. An individual MSW landfill may emit more or less than
calculated based on site-specific factors. The AP-42 document also
provides calculations for the use and adjustment of site-specific data,
if it is available (that is, to adjust measured NMOC concentration data
for air infiltration). If site-specific measured values are available,
it is preferable to use these rather than the default values.

It should be stressed that the AP-42 default values should NOT be used
to determine applicability of or compliance with the MSW landfills
Emission Guidelines. Under the Emission Guidelines and the NSPS, the
owner or operator must use the tiered emission estimation procedure in
§ 60.754 of Subpart WWW or another method if it has been approved by the
EPA Administrator as provided in § 60.752(b)(2)(i)(B) to determine
whether the annual emission rate equals or exceeds the 50 Mg/yr cutoff
and whether the MSW landfill must be controlled. The owner or operator
must use the equations and Tier 1 default values provided in the NSPS
and the Emission Guidelines to determine NMOC emissions or develop
site-specific values using the Tier 2 or 3 procedures in § 60.754. The
equations in Subpart WWW are the same as the AP-42 equations. However,
the Tier 1 default values for methane generation potential (L~o~) and
methane generation rate constant (k) provided in the NSPS and the
Emission Guidelines are purposefully conservative to protect human
health, to encompass a wide range of MSW landfills, and to encourage the
use of site-specific data.

For more information about the AP-42 emission factors and documentation
of the assumptions and calculations, see Chapter 2 in AP-42. The current
version of AP-42 is included in this appendix (November 1998). Because
AP-42 is updated periodically, the AP-42 section in this appendix should
not be used for subsequent emission inventories unless verified to be
current. For current information in AP-42, check the TTN Web at
http:www.epa.gov/ttn/chief.

A computer model is also available to calculate MSW landfill emissions.
The \"Landfill Gas Emissions Model\", utilizes a first-order
decomposition model that is consistent with AP-42 and the NSPS and
Emission Guidelines equations to estimate emissions of methane, carbon
dioxide, NMOC and other pollutants. The model combines user-entered
landfill operating characteristics with defaults derived from either the
MSW landfills NSPS and Emission Guidelines or AP-42 to provide yearly
estimates of gaseous emissions. These estimates may be displayed as text
or in graphical depictions. The model also allows the user to replace
internal defaults with landfill specific parameters to refine the
calculations for a specific site.

The model is consistent with the equations specified in the MSW landfill
NSPS and Emission Guidelines. MSW landfills using the model to calculate
annual emission rates for purposes of NSPS or Emission Guidelines
applicability determination must use the NSPS default values rather than
the AP-42 default values. Those using the model for a state emissions
inventory or for NSR or PSD permitting purposes should use site-specific
measured values, and if these are not available, the AP-42 defaults.

A package with a diskette containing the model as well as the user\'s
guide is available under the title: \"Landfill Gas Emissions Model,
Users Manual,\" Version 2.01 and may be purchased from:

> National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Telephone: (703) 487-4650

> or:
>
> accessed on the EPA TTN Web at
> http://www.epa.gov/ttn/catc/products.html# software.

Additionally, information or questions regarding the models and their
operation may be obtained from Susan A. Thorneloe, the EPA Project
Officer overseeing its development. She may be contacted at:

> Air and Energy Engineering Research Laboratory

U.S. Environmental Protection Agency

Research Triangle Park, NC 27711

Fax: (919) 541-2382

thorneloe.susan@epamail.epa.gov

REFERENCES

1\. U.S. EPA. Compilation of Air Pollutant Emission Factors, 5th ed.
(AP-42), Volume I: Stationary Point and Area Sources, Section 2.4:
Municipal Solid Waste Landfills,\" Research Triangle Park, North
Carolina: U.S. Environmental Protection Agency, Office of Air Quality
Planning and Standards, November, 1998.

**2.4 MUNICIPAL SOLID WASTE LANDFILLS**

2.4.1 General^1-4^

A municipal solid waste (MSW) landfill unit is a discrete area of land
or an excavation that receives household waste, and that is not a land
application unit, surface impoundment, injection well, or waste pile. An
MSW landfill unit may also receive other types of wastes, such as
commercial solid waste, nonhazardous sludge, and industrial solid waste.
The municipal solid waste types potentially accepted by MSW landfills
include (most landfills accept only a few of the following categories):

> • MSW,
>
> • Household hazardous waste,
>
> • Municipal sludge,
>
> • Municipal waste combustion ash,
>
> • Infectious waste,
>
> • Waste tires,
>
> • Industrial non-hazardous waste,
>
> • Conditionally exempt small quantity generator (CESQG) hazardous
> waste,
>
> • Construction and demolition waste,
>
> • Agricultural wastes,
>
> • Oil and gas wastes, and
>
> • Mining wastes.

In the United States, approximately 57 percent of solid waste is
landfilled, 16 percent is incinerated, and 27 percent is recycled or
composted. There were an estimated 2,500 active MSW landfills in the
United States in 1995. These landfills were estimated to receive 189
million megagrams (Mg) (208 million tons) of waste annually, with 55 to
60 percent reported as household waste, and 35 to 45 percent reported as
commercial waste.

2.4.2 Process Description^2,5^

There are three major designs for municipal landfills. These are the
area, trench, and ramp methods. All of these methods utilize a three
step process, which includes spreading the waste, compacting the waste,
and covering the waste with soil. The trench and ramp methods are not
commonly used, and are not the preferred methods when liners and
leachate collection systems are utilized or required by law. The area
fill method involves placing waste on the ground surface or landfill
liner, spreading it in layers, and compacting with heavy equipment. A
daily soil cover is spread over the compacted waste. The trench method
entails excavating trenches designed to receive a day\'s worth of waste.
The soil from the excavation is often used for cover material and wind
breaks. The ramp method is typically employed on sloping land, where
waste is spread and compacted similar to the area method, however, the
cover material obtained is generally from the front of the working face
of the filling operation.

Modern landfill design often incorporates liners constructed of soil
(i.e., recompacted clay), or synthetics (i.e., high density
polyethylene), or both to provide an impermeable barrier to leachate
(i.e., water that has passed through the landfill) and gas migration
from the landfill.

2.4.3 Control Technology^1,2,6^

The Resource Conservation and Recovery Act (RCRA) Subtitle D regulations
promulgated on October 9, 1991 require that the concentration of methane
generated by MSW landfills not exceed 25 percent of the lower explosive
limit (LEL) in on-site structures, such as scale houses, or the LEL at
the facility property boundary.

The New Source Performance Standards (NSPS) and Emission Guidelines for
air emissions from MSW landfills for certain new and existing landfills
were published in the Federal Register on March 1, 1996. The regulation
requires that Best Demonstrated Technology (BDT) be used to reduce MSW
landfill emissions from affected new and existing MSW landfills emitting
greater than or equal to 50 Mg/yr (55 tons/yr) of non-methane organic
compounds (NMOCs). The MSW landfills that are affected by the
NSPS/Emission Guidelines are each new MSW landfill, and each existing
MSW landfill that has accepted waste since November 8, 1987, or that has
capacity available for future use. The NSPS/Emission Guidelines
\[require control systems for \] ~~affect~~ landfills with a design
capacity of 2.5 million Mg (2.75 million tons) \[and 2.5 million cubic
meters (3.27 million cubic yards) that emit greater than or equal to
50 Mg/yr NMOCs\]\* ~~or more~~. Control systems require: (1) a
well-designed and well-operated gas collection system, and (2) a control
device capable of reducing NMOCs in the collected gas by 98
weight-percent.

Landfill gas (LFG) collection systems are either active or passive
systems. Active collection systems provide a pressure gradient in order
to extract LFG by use of mechanical blowers or compressors. Passive
systems allow the natural pressure gradient created by the increase in
pressure created by LFG generation within the landfill to mobilize the
gas for collection.

LFG control and treatment options include (1) combustion of the LFG, and
(2) purification of the LFG. Combustion techniques include techniques
that do not recover energy (i.e., flares and thermal incinerators), and
techniques that recover energy (i.e., gas turbines and internal
combustion engines) and generate electricity from the combustion of the
LFG. Boilers can also be employed to recover energy from LFG in the form
of steam. Flares involve an open combustion process that requires oxygen
for combustion, and can be open or enclosed. Thermal incinerators heat
an organic chemical to a high enough temperature in the presence of
sufficient oxygen to oxidize the chemical to carbon dioxide (CO~2~) and
water. Purification techniques can also be used to process raw landfill
gas to pipeline quality natural gas by using adsorption, absorption, and
membranes.

\*\[This clarification will be reflected in the next revision of
AP-42.\]

2.4.4 Emissions^2,7^

Methane (CH~4~) and CO~2~ are the primary constituents of landfill gas,
and are produced by microorganisms within the landfill under anaerobic
conditions. Transformations of CH~4~ and CO~2~ are mediated by microbial
populations that are adapted to the cycling of materials in anaerobic
environments. Landfill gas generation, including rate and composition,
proceeds through four phases. The first phase is aerobic \[i.e., with
oxygen (O~2~) available\] and the primary gas produced is CO~2~. The
second phase is characterized by O~2~ depletion, resulting in an
anaerobic environment, where large amounts of CO~2~ and some hydrogen
(H~2~) are produced. In the third phase, CH~4~ production begins, with
an accompanying reduction in the amount of CO~2~ produced. Nitrogen
(N~2~) content is initially high in landfill gas in the first phase, and
declines sharply as the landfill proceeds through the second and third
phases. In the fourth phase, gas production of CH~4~, CO~2~, and N~2~
becomes fairly steady. The total time and phase duration of gas
generation varies with landfill conditions (i.e., waste composition,
design management, and anaerobic state).

Typically, LFG also contains a small amount of non-methane organic
compounds (NMOC). This NMOC fraction often contains various organic
hazardous air pollutants (HAP), greenhouse gases (GHG), and compounds
associated with stratospheric ozone depletion. The NMOC fraction also
contains volatile organic compounds (VOC). The weight fraction of VOC
can be determined by subtracting the weight fractions of individual
compounds that are non-photochemically reactive (i.e.,
negligibly-reactive organic compounds as defined in 40 CFR 51.100).

Other emissions associated with MSW landfills include combustion
products from LFG control and utilization equipment (i.e., flares,
engines, turbines, and boilers). These include carbon monoxide (CO),
oxides of nitrogen (NO~x~), sulfur dioxide (SO~2~), hydrogen chloride
(HCl), particulate matter (PM) and other combustion products (including
HAPs). PM emissions can also be generated in the form of fugitive dust
created by mobile sources (i.e., garbage trucks) traveling along paved
and unpaved surfaces. The reader should consult AP-42 Volume I Sections
13.2.1 and 13.2.2 for information on estimating fugitive dust emissions
from paved and unpaved roads.

The rate of emissions from a landfill is governed by gas production and
transport mechanisms. Production mechanisms involve the production of
the emission constituent in its vapor phase through vaporization,
biological decomposition, or chemical reaction. Transport mechanisms
involve the transportation of a volatile constituent in its vapor phase
to the surface of the landfill, through the air boundary layer above the
landfill, and into the atmosphere. The three major transport mechanisms
that enable transport of a volatile constituent in its vapor phase are
diffusion, convection, and displacement.

2.4.4.1 Uncontrolled Emissions --- To estimate uncontrolled emissions of
the various compounds present in landfill gas, total landfill gas
emissions must first be estimated. Uncontrolled CH~4~ emissions may be
estimated for individual landfills by using a theoretical first-order
kinetic model of methane production developed by the EPA.^8^ This model
is known as the Landfill Air Emissions Estimation model, and can be
accessed from the Office of Air Quality Planning and Standards
Technology Transfer Network Website (OAQPS TTN Web) in the Clearinghouse
for Inventories and Emission Factors (CHIEF) technical area (URL

http://www.epa.gov/ttn/chief). The Landfill Air Emissions Estimation
model equation is as follows:

where:

QCH~4~ = Methane generation rate at time t, m^3^/yr;

Lo = Methane generation potential, m^3^ CH~4~/Mg refuse;

R = Average annual refuse acceptance rate during active life, Mg/yr;

e = Base log, unitless;

k = Methane generation rate constant, yr^-1^;

c = Time since landfill closure, yrs (c = 0 for active landfills); and

t = Time since the initial refuse placement, yrs.

It should be noted that the model above was designed to estimate LFG
generation and not LFG emissions to the atmosphere. Other fates may
exist for the gas generated in a landfill, including capture and
subsequent microbial degradation within the landfill's surface layer.
Currently, there are no data that adequately address this fate. It is
generally accepted that the bulk of the gas generated will be emitted
through cracks or other openings in the landfill surface.

Site-specific landfill information is generally available for variables
R, c, and t. When refuse acceptance rate information is scant or
unknown, R can be determined by dividing the refuse in place by the age
of the landfill. If a facility has documentation that a certain segment
(cell) of a landfill received *only* nondegradable refuse, then the
waste from this segment of the landfill can be excluded from the
calculation of R. Nondegradable refuse includes concrete, brick, stone,
glass, plaster, wallboard, piping, plastics, and metal objects. The
average annual acceptance rate should only be estimated by this method
when there is inadequate information available on the actual average
acceptance rate. The time variable, t, includes the total number of
years that the refuse has been in place (including the number of years
that the landfill has accepted waste and, if applicable, has been
closed).

Values for variables L~o~ and k must be estimated. Estimation of the
potential CH~4~ generation capacity of refuse (L~o~) is generally
treated as a function of the moisture and organic content of the refuse.
Estimation of the CH~4~ generation constant (k) is a function of a
variety of factors, including moisture, pH, temperature, and other
environmental factors, and landfill operating conditions. Specific CH~4~
generation constants can be computed by the use of EPA Method 2E (40 CFR
Part 60 Appendix A).

The Landfill Air Emission Estimation model includes both regulatory
default values and recommended AP-42 default values for L~o~ and k. The
regulatory defaults were developed for compliance purposes
(NSPS/Emission Guideline). As a result, the model contains conservative
L~o~ and k default values in order to protect human health, to encompass
a wide range of landfills, and to encourage the use of site-specific
data. Therefore, different L~o~ and k values may be appropriate in
estimating landfill emissions for particular landfills and for use in an
emissions inventory.

Recommended AP-42 defaults include a k value of 0.04/yr for areas
recieving 25 inches or more of rain per year. A default k of 0.02/yr
should be used in drier areas (\<25 inches/yr). An L~o~ value of
100 m^3^/Mg (3,530 ft^3^/ton) refuse is appropriate for most landfills.
Although the recommended default k and L~o~ are based upon the best fit
to 21 different landfills, the predicted methane emissions ranged from
38 to 492% of actual, and had a relative standard deviation of 0.85. It
should be emphasized that in order to comply with the NSPS/Emission
Guideline, the regulatory defaults for k and L~o~ must be applied as
specified in the final rule.

When gas generation reaches steady state conditions, LFG consists of
approximately 40 percent by volume CO~2~, 55 percent CH~4~, 5 percent
N~2~ (and other gases), and trace amounts of NMOCs. Therefore, the
estimate derived for CH~4~ generation using the Landfill Air Emissions
Estimation model can also be used to represent CO~2~ generation.
Addition of the CH~4~ and CO~2~ emissions will yield an estimate of
total landfill gas emissions. If site-specific information is available
to suggest that the CH~4~ content of landfill gas is not 55 percent,
then the site-specific information should be used, and the CO~2~
emission estimate should be adjusted accordingly.

Most of the NMOC emissions result from the volatilization of organic
compounds contained in the landfilled waste. Small amounts may be
created by biological processes and chemical reactions within the
landfill. The current version of the Landfill Air Emissions Estimation
model contains a proposed regulatory default value for total NMOC of
4,000 ppmv, expressed as hexane. However, available data show that there
is a range of over 4,400 ppmv for total NMOC values from landfills. The
proposed regulatory default value for NMOC concentration was developed
for regulatory compliance purposes and to provide the most
cost-effective default values on a national basis. For emissions
inventory purposes, site-specific information should be taken into
account when determining the total NMOC concentration. In the absence of
site-specific information, a value of 2,420 ppmv as hexane is suggested
for landfills known to have co-disposal of MSW and non-residential
waste. If the landfill is known to contain only MSW or have very little
organic commercial/industrial wastes, then a total NMOC value of 595
ppmv as hexane should be used. In addition, as with the landfill model
defaults, the regulatory default value for NMOC content must be used in
order to comply with the NSPS/Emission Guideline.

If a site-specific total pollutant concentration is available (i.e., as
measured by EPA Reference Method 25C), it must be corrected for air
infiltration which can occur by two different mechanisms: LFG sample
dilution, and air intrusion into the landfill. These corrections require
site-specific data for the LFG CH~4~,

CO~2~, nitrogen (N~2~), and oxygen (O~2~) content. If the ratio of N~2~
to O~2~ is less than or equal to 4.0 (as found in ambient air), then the
total pollutant concentration is adjusted for sample dilution by
assuming that CO~2~ and CH~4~ are the primary (100 percent) constituents
of landfill gas, and the following equation is used:

where:

CP = Concentration of pollutant P in landfill gas (i.e., NMOC as
hexane), ppmv;

CCO~2~ = CO~2~ concentration in landfill gas, ppmv;

CCH~4~ = CH~4~ Concentration in landfill gas, ppmv; and

1 x 10^6^ = Constant used to correct concentration of P to units of
ppmv.

If the ratio of N~2~ to O~2~ concentrations (i.e., CN~2~ , CO~2~ ) is
greater than 4.0, then the total pollutant concentration should be
adjusted for air intrusion into the landfill by using equation 2 and
adding the concentration of N~2~ (i.e., CN~2~ ) to the denominator.
Values for CCO~2~ , CCH~4~ , CN~2~ , CO~2~ , can usually be found in the
source test report for the particular landfill along with the total
pollutant concentration data.

To estimate emissions of NMOC or other landfill gas constituents, the
following equation should be used:

where:

QP = Emission rate of pollutant P (i.e. NMOC), m^3^/yr;

QCH~4~ = CH~4~ generation rate, m^3^/yr (from the Landfill Air Emissions
Estimation model);

CP = Concentration of P in landfill gas, ppmv; and

1.82 = Multiplication factor (assumes that approximately 55 percent of
landfill gas is CH~4~ and 45 percent is CO~2~, N~2~, and other
constituents).

Uncontrolled mass emissions per year of total NMOC (as hexane), CO~2~,
CH~4~, and speciated organic and inorganic compounds can be estimated by
the following equation:

where:

UMP = Uncontrolled mass emissions of pollutant P (i.e., NMOC), kg/yr;

MWP = Molecular weight of P, g/gmol (i.e., 86.18 for NMOC as hexane);

> QP = NMOC emission rate of P, m^3^/yr; and

T = Temperature of landfill gas, ^o^C.

This equation assumes that the operating pressure of the system is
approximately 1 atmosphere. If the temperature of the landfill gas is
not known, a temperature of 25^o^C (77^o^F) is recommended.

Uncontrolled default concentrations of speciated organics along with
some inorganic compounds are presented in Table 2.4-1. These default
concentrations have already been corrected for air infiltration and can
be used as input parameters to equation 3 or the Landfill Air Emission
Estimation model for estimating speciated emissions from landfills when
site-specific data are not available. An analysis of the data, based on
the co-disposal history (with non-residential wastes) of the individual
landfills from which the concentration data were derived, indicates that
for benzene, NMOC, and toluene, there is a difference in the
uncontrolled concentrations. Table 2.4-2 presents the corrected
concentrations for benzene, NMOC, and toluene to use based on the
site\'s co-disposal history.

It is important to note that the compounds listed in Tables 2.4-1 and
2.4-2 are not the only compounds likely to be present in LFG. The listed
compounds are those that were identified through a review of the
available literature. The reader should be aware that additional
compounds are likely present, such as those associated with consumer or
industrial products. Given this information, extreme caution should be
exercised in the use of the default VOC weight fractions and
concentrations given at the bottom of Table 2.4-2. These default VOC
values are heavily influenced by the ethane content of the LFG.
Available data have shown that there is a range of over 1,500 ppmv in
LFG ethane content among landfills.

2.4.4.2 Controlled Emissions --- Emissions from landfills are typically
controlled by installing a gas collection system, and combusting the
collected gas through the use of internal combustion engines, flares, or
turbines. Gas collection systems are not 100 percent efficient in
collecting landfill gas, so emissions of CH~4~ and NMOC at a landfill
with a gas recovery system still occur. To estimate controlled emissions
of CH~4~, NMOC, and other constituents in landfill gas, the collection
efficiency of the system must first be estimated. Reported collection
efficiencies typically range from 60 to 85 percent, with an average of
75 percent most commonly assumed. Higher collection efficiencies may be
achieved at some sites (i.e., those engineered to control gas
emissions). If site-specific collection efficiencies are available
(i.e., through a comprehensive surface sampling program), then they
should be used instead of the 75 percent average.

Controlled emission estimates also need to take into account the control
efficiency of the control device. Control efficiencies based on test
data for the combustion of CH~4~, NMOC, and some speciated organics with
differing control devices are presented in Table 2.4-3. Emissions from
the control devices need to be added to the uncollected emissions to
estimate total controlled emissions.

Controlled CH~4~, NMOC, and speciated emissions can be calculated with
equation 5. It is assumed that the landfill gas collection and control
system operates 100 percent of the time. Minor durations of system
downtime associated with routine maintenance and repair (i.e., 5 to 7
percent) will not appreciably effect emission estimates. The first term
in equation 5 accounts for emissions from uncollected landfill gas,
while the second term accounts for emissions of the pollutant that were
collected but not combusted in the control or utilization device:

where:

CMP = Controlled mass emissions of pollutant P, kg/yr;

UMP = Uncontrolled mass emissions of P, kg/yr (from equation 4 or the
Landfill Air Emissions Estimation Model);

η~col~ = Collection efficiency of the landfill gas collection system,
percent; and

η~cnt~ = Control efficiency of the landfill gas control or utilization
device, percent.

Emission factors for the secondary compounds, CO and NO~x~, exiting the
control device are presented in Tables 2.4-4 and 2.4-5. These emission
factors should be used when equipment vendor guarantees are not
available.

Controlled emissions of CO~2~ and sulfur dioxide (SO~2~) are best
estimated using site-specific landfill gas constituent concentrations
and mass balance methods.^68^ If site-specific data are not available,
the data in tables 2.4-1 through 2.4-3 can be used with the mass balance
methods that follow.

Controlled CO~2~ emissions include emissions from the CO~2~ component of
landfill gas (equivalent to uncontrolled emissions) and additional CO~2~
formed during the combustion of landfill gas. The bulk of the CO~2~
formed during landfill gas combustion comes from the combustion of the
CH~4~ fraction. Small quantities will be formed during the combustion of
the NMOC fraction, however, this typically amounts to less than 1
percent of total CO~2~ emissions by weight. Also, the formation of CO
through incomplete combustion of landfill gas will result in small
quantities of CO~2~ not being formed. This contribution to the overall
mass balance picture is also very small and does not have a significant
impact on overall CO~2~ emissions.^68^

The following equation which assumes a 100 percent combustion efficiency
for CH~4~ can be used to estimate CO~2~ emissions from controlled
landfills:

where:

CMCO~2~ = Controlled mass emissions of CO~2~, kg/yr;

UMCO~2~ = Uncontrolled mass emissions of CO~2~, kg/yr (from equation 4
or the Landfill Air Emission Estimation Model);

UMCH~4~ = Uncontrolled mass emissions of CH~4~, kg/yr (from equation 4
on the Landfill Air Emission Estimation Model);

η~col~ = Efficiency of the landfill gas collection system, percent; and

2.75 = Ratio of the molecular weight of CO~2~ to the molecular weight of
CH~4~.

To prepare estimates of SO~2~ emissions, data on the concentration of
reduced sulfur compounds within the landfill gas are needed. The best
way to prepare this estimate is with site-specific information on the
total reduced sulfur content of the landfill gas. Often these data are
expressed in ppmv as sulfur (S). Equations 3 and 4 should be used first
to determine the uncontrolled mass emission rate of reduced sulfur
compounds as sulfur. Then, the following equation can be used to
estimate SO~2~ emissions:

where:

CMSO~2~ = Controlled mass emissions of SO~2~, kg/yr;

> UMS = Uncontrolled mass emissions of reduced sulfur compounds as
> sulfur, kg/yr (from equations 3 and 4);

η~col~ = Efficiency of the landfill gas collection system, percent; and

2.0 = Ratio of the molecular weight of SO~2~ to the molecular weight of
S.

The next best method to estimate SO~2~ concentrations, if site-specific
data for total reduced sulfur compounds as sulfur are not available, is
to use site-specific data for speciated reduced sulfur compound
concentrations. These data can be converted to ppmv as S with equation
8. After the total reduced sulfur as S has been obtained from equation
8, then equations 3, 4, and 7 can be used to derive SO~2~ emissions.

where:

CS = Concentration of total reduced sulfur compounds, ppmv as S (for use
in equation 3);

CP = Concentration of each reduced sulfur compound, ppmv;

SP = Number of moles of S produced from the combustion of each reduced
sulfur compound (i.e., 1 for sulfides, 2 for disulfides); and

n = Number of reduced sulfur compounds available for summation.

If no site-specific data are available, a value of 46.9 ppmv can be
assumed for C~S~ (for use in equation 3). This value was obtained by
using the default concentrations presented in Table 2.4-1 for reduced
sulfur compounds and equation 8.

Hydrochloric acid \[Hydrogen Chloride (HCl)\] emissions are formed when
chlorinated compounds in LFG are combusted in control equipment. The
best methods to estimate emissions are mass balance methods that are
analogous to those presented above for estimating SO~2~ emissions.
Hence, the best source of data to estimate HCl emissions is
site-specific LFG data on total chloride \[expressed in ppmv as the
chloride ion (Cl^-^)\]. If these data are not available, then total
chloride can be estimated from data on individual chlorinated species
using equation 9 below. However, emission estimates may be
underestimated, since not every chlorinated compound in the LFG will be
represented in the laboratory report (i.e., only those that the
analytical method specifies).

where:

CCl = Concentration of total chloride, ppmv as Cl^-^ (for use in
equation 3);

CP = Concentration of each chlorinated compound, ppmv;

ClP = Number of moles of Cl^-^ produced from the combustion of each
chlorinated compound (i.e., 3 for 1,1,1-trichloroethane); and

n = Number of chlorinated compounds available for summation.

After the total chloride concentration (C~Cl~) has been estimated,
equations 3 and 4 should be used to determine the total uncontrolled
mass emission rate of chlorinated compounds as chloride ion (UM~Cl~).
This value is then used in equation 10 below to derive HCl emission
estimates:

where:

CMHCl = Controlled mass emissions of HCl, kg/yr;

UMCl = Uncontrolled mass emissions of chlorinated compounds as chloride,
kg/yr (from equations 3 and 4);

η~col~ = Efficiency of the landfill gas collection system, percent;

1.03 = Ratio of the molecular weight of HCl to the molecular weight of
Cl^-^; and

η~cnt~ = Control efficiency of the landfill gas control or utilization
device, percent.

In estimating HCl emissions, it is assumed that all of the chloride ion
from the combustion of chlorinated LFG constituents is converted to HCl.
If an estimate of the control efficiency, η~cnt~, is not available, then
the high end of the control efficiency range for the equipment listed in
Table 9 should be used. This assumption is recommended to assume that
HCl emissions are not under-estimated.

If site-specific data on total chloride or speciated chlorinated
compounds are not available, then a default value of 42.0 ppmv can be
used for C~Cl~. This value was derived from the default LFG constituent
concentrations presented in Table 2.4-1. As mentioned above, use of this
default may produce underestimates of HCl emissions since it is based
only on those compounds for which analyses have been performed. The
constituents listed in Table 2.4-1are likely not all of the chlorinated
compounds present in LFG.

The reader is referred to Sections 11.2-1 (Unpaved Roads, SCC 50100401),
and 11-2.4 (Heavy Construction Operations) of Volume I, and Section II-7
(Construction Equipment) of Volume II, of the AP-42 document for
determination of associated fugitive dust and exhaust emissions from
these emission sources at MSW landfills.

2.4.5 Updates Since the Fifth Edition

The Fifth Edition was released in January 1995. This is revision
includes major revisions of the text and recommended emission factors
conained in the section. The most significant revisions to this section
since publication in the Fifth Edition are summarized below.

 The equations to calculate the CH4, CO2 and other constituents were
simplified.

 The default L0 and k were revised based upon an expanded base of gas
generation data.

 The default ratio of CO2 to CH4 was revised based upon averages
observed in available source test reports.

 The default concentrations of LFG constituents were revised based upon
additional data.

 Additional control efficiencies were included and existing
efficiencies were revised based upon additional emission test data.

 Revised and expanded the recommended emission factors for secondary
compounds emitted from typical control devices.

Table 2.4-1. DEFAULT CONCENTRATIONS FOR LFG CONSTITUENTS^a^

(SCC 50100402, 50300603)

+--------------------------------+-----------+------------+-----------+
| Compound                       | Molecular | Default    | Emission  |
|                                | Weight    | Con        | Factor    |
|                                |           | centration | Rating    |
|                                |           |            |           |
|                                |           | (ppmv)     |           |
+================================+===========+============+===========+
| 1,1,1-Trichloroethane          | 133.42    | 0.48       | B         |
| (methyl chloroform)^a^         |           |            |           |
+--------------------------------+-----------+------------+-----------+
| 1,1,2,2-Tetrachloroethane^a^   | 167.85    | 1.11       | C         |
+--------------------------------+-----------+------------+-----------+
| 1,1-Dichloroethane             | 98.95     | 2.35       | B         |
| (ethylidene dichloride)^a^     |           |            |           |
+--------------------------------+-----------+------------+-----------+
| 1,1-Dichloroethene             | 96.94     | 0.20       | B         |
| (vinylidene chloride)^a^       |           |            |           |
+--------------------------------+-----------+------------+-----------+
| 1,2-Dichloroethane             | 98.96     | 0.41       | B         |
| (ethylene dichloride)^a^       |           |            |           |
+--------------------------------+-----------+------------+-----------+
| 1,2-Dichloropropane            | 112.98    | 0.18       | D         |
| (propylene dichloride)^a^      |           |            |           |
+--------------------------------+-----------+------------+-----------+
| 2-Propanol (isopropyl alcohol) | 60.11     | 50.1       | E         |
+--------------------------------+-----------+------------+-----------+
| Acetone                        | 58.08     | 7.01       | B         |
+--------------------------------+-----------+------------+-----------+
| Acrylonitrile^a^               | 53.06     | 6.33       | D         |
+--------------------------------+-----------+------------+-----------+
| Bromodichloromethane           | 163.83    | 3.13       | C         |
+--------------------------------+-----------+------------+-----------+
| Butane                         | 58.12     | 5.03       | C         |
+--------------------------------+-----------+------------+-----------+
| Carbon disulfide^a^            | 76.13     | 0.58       | C         |
+--------------------------------+-----------+------------+-----------+
| Carbon monoxide^b^             | 28.01     | 141        | E         |
+--------------------------------+-----------+------------+-----------+
| Carbon tetrachloride^a^        | 153.84    | 0.004      | B         |
+--------------------------------+-----------+------------+-----------+
| Carbonyl sulfide^a^            | 60.07     | 0.49       | D         |
+--------------------------------+-----------+------------+-----------+
| Chlorobenzene^a^               | 112.56    | 0.25       | C         |
+--------------------------------+-----------+------------+-----------+
| Chlorodifluoromethane          | 86.47     | 1.30       | C         |
+--------------------------------+-----------+------------+-----------+
| Chloroethane                   | 64.52     | 1.25       | B         |
| (ethyl chloride)^a^            |           |            |           |
+--------------------------------+-----------+------------+-----------+
| Chloroform^a^                  | 119.39    | 0.03       | B         |
+--------------------------------+-----------+------------+-----------+
| Chloromethane                  | 50.49     | 1.21       | B         |
+--------------------------------+-----------+------------+-----------+
| Dichlorobenzene^c^             | 147       | 0.21       | E         |
+--------------------------------+-----------+------------+-----------+
| Dichlorodifluoromethane        | 120.91    | 15.7       | A         |
+--------------------------------+-----------+------------+-----------+
| Dichlorofluoromethane          | 102.92    | 2.62       | D         |
+--------------------------------+-----------+------------+-----------+
| Dichloromethane                | 84.94     | 14.3       | A         |
| (methylene chloride)^a^        |           |            |           |
+--------------------------------+-----------+------------+-----------+
| Dimethyl sulfide (methyl       | 62.13     | 7.82       | C         |
| sulfide)                       |           |            |           |
+--------------------------------+-----------+------------+-----------+
| Ethane                         | 30.07     | 889        | C         |
+--------------------------------+-----------+------------+-----------+
| Ethanol                        | 46.08     | 27.2       | E         |
+--------------------------------+-----------+------------+-----------+
| Ethyl mercaptan (ethanethiol)  | 62.13     | 2.28       | D         |
+--------------------------------+-----------+------------+-----------+
| Ethylbenzene^a^                | 106.16    | 4.61       | B         |
+--------------------------------+-----------+------------+-----------+
| Ethylene dibromide             | 187.88    | 0.001      | E         |
+--------------------------------+-----------+------------+-----------+
| Fluorotrichloromethane         | 137.38    | 0.76       | B         |
+--------------------------------+-----------+------------+-----------+
| Hexane^a^                      | 86.18     | 6.57       | B         |
+--------------------------------+-----------+------------+-----------+
| Hydrogen sulfide               | 34.08     | 35.5       | B         |
+--------------------------------+-----------+------------+-----------+
| Mercury (total)^a,d^           | 200.61    | 2          | E         |
|                                |           | .92x10^-4^ |           |
+--------------------------------+-----------+------------+-----------+
| Methyl ethyl ketone^a^         | 72.11     | 7.09       | A         |
+--------------------------------+-----------+------------+-----------+
| Methyl isobutyl ketone^a^      | 100.16    | 1.87       | B         |
+--------------------------------+-----------+------------+-----------+
| Methyl mercaptan               | 48.11     | 2.49       | C         |
+--------------------------------+-----------+------------+-----------+
| Pentane                        | 72.15     | 3.29       | C         |
+--------------------------------+-----------+------------+-----------+
| Perchloroethylene              | 165.83    | 3.73       | B         |
| (tetrachloroethylene)^a^       |           |            |           |
+--------------------------------+-----------+------------+-----------+
| Propane                        | 44.09     | 11.1       | B         |
+--------------------------------+-----------+------------+-----------+
| t-1,2-dichloroethene           | 96.94     | 2.84       | B         |
+--------------------------------+-----------+------------+-----------+
| Trichloroethylene              | 131.38    | 2.82       | B         |
| (trichloroethene)^a^           |           |            |           |
+--------------------------------+-----------+------------+-----------+
| Vinyl chloride^a^              | 62.50     | 7.34       | B         |
+--------------------------------+-----------+------------+-----------+
| Xylenes^a^                     | 106.16    | 12.1       | B         |
+--------------------------------+-----------+------------+-----------+
| NOTE: This is not an           |           |            |           |
| all-inclusive list of          |           |            |           |
| potential LFG constituents,    |           |            |           |
| only those for which test data |           |            |           |
| were available at multiple     |           |            |           |
| sites. References 10-67.       |           |            |           |
| Source Classification Codes in |           |            |           |
| parentheses.                   |           |            |           |
|                                |           |            |           |
| ^a^ Hazardous Air Pollutants   |           |            |           |
| listed in Title III of the     |           |            |           |
| 1990 Clean Air Act Amendments. |           |            |           |
|                                |           |            |           |
| ^b^ Carbon monoxide is not a   |           |            |           |
| typical constituent of LFG,    |           |            |           |
| but does exist in instances    |           |            |           |
| involving landfill             |           |            |           |
| (underground) combustion.      |           |            |           |
| Therefore, this default value  |           |            |           |
| should be used with caution.   |           |            |           |
| Of 18 sites where CO was       |           |            |           |
| measured, only 2 showed        |           |            |           |
| detectable levels of CO.       |           |            |           |
|                                |           |            |           |
| ^c^ Source tests did not       |           |            |           |
| indicate whether this compound |           |            |           |
| was the para- or ortho-        |           |            |           |
| isomer. The para isomer is a   |           |            |           |
| Title III-listed HAP.          |           |            |           |
|                                |           |            |           |
| ^d^ No data were available to  |           |            |           |
| speciate total Hg into the     |           |            |           |
| elemental and organic forms.   |           |            |           |
+--------------------------------+-----------+------------+-----------+

Table 2.4-2. DEFAULT CONCENTRATIONS OF BENZENE, NMOC, AND TOLUENE BASED
ON WASTE DISPOSAL HISTORY^a^

(SCC 50100402, 50300603)

+--------------------------+----------+-----------------+-------------+
| Pollutant                | M        | Default         | Emission    |
|                          | olecular |                 | Factor      |
|                          | Weight   | Concentration   | Rating      |
|                          |          |                 |             |
|                          |          | (ppmv)          |             |
+--------------------------+----------+-----------------+-------------+
| Benzene^b^               | 78.11    |                 |             |
+--------------------------+----------+-----------------+-------------+
| Co-disposal              |          | 11.1            | D           |
+--------------------------+----------+-----------------+-------------+
| No or Unknown            |          | 1.91            | B           |
| co-disposal              |          |                 |             |
+--------------------------+----------+-----------------+-------------+
| NMOC (as hexane)^c^      | 86.18    |                 |             |
+--------------------------+----------+-----------------+-------------+
| Co-disposal              |          | 2420            | D           |
+--------------------------+----------+-----------------+-------------+
| No or Unknown            |          | 595             | B           |
| co-disposal              |          |                 |             |
+--------------------------+----------+-----------------+-------------+
| Toluene^b^               | 92.13    |                 |             |
+--------------------------+----------+-----------------+-------------+
| Co-disposal              |          | 165             | D           |
+--------------------------+----------+-----------------+-------------+
| No or Unknown            |          | 39.3            | A           |
| co-disposal              |          |                 |             |
+--------------------------+----------+-----------------+-------------+
| ^a^ References 10-54.    |          |                 |             |
| Source Classification    |          |                 |             |
| Codes in parentheses.    |          |                 |             |
|                          |          |                 |             |
| ^b^ Hazardous Air        |          |                 |             |
| Pollutants listed in     |          |                 |             |
| Title III of the 1990    |          |                 |             |
| Clean Air Act            |          |                 |             |
| Amendments.              |          |                 |             |
|                          |          |                 |             |
| ^c^ For NSPS/Emission    |          |                 |             |
| Guideline compliance     |          |                 |             |
| purposes, the default    |          |                 |             |
| concentration for NMOC   |          |                 |             |
| as specified in the      |          |                 |             |
| final rule must be used. |          |                 |             |
| For purposes not         |          |                 |             |
| associated with          |          |                 |             |
| NSPS/Emission Guideline  |          |                 |             |
| compliance, the default  |          |                 |             |
| VOC content at           |          |                 |             |
| co-disposal sites = 85   |          |                 |             |
| percent by weight (2,060 |          |                 |             |
| ppmv as hexane); at No   |          |                 |             |
| or Unknown sites = 39    |          |                 |             |
| percent by weight 235    |          |                 |             |
| ppmv as hexane).         |          |                 |             |
+--------------------------+----------+-----------------+-------------+

Table 2.4-3. CONTROL EFFICIENCIES FOR LFG CONSTITUENTS^a^

+------------------+-------------------+---------+----------+----------+
| Control Device   | Constituent^b^    | Control |          |          |
|                  |                   | Eff     |          |          |
|                  |                   | iciency |          |          |
|                  |                   | (%)     |          |          |
+------------------+-------------------+---------+----------+----------+
|                  |                   | Typical | Range    | Rating   |
+------------------+-------------------+---------+----------+----------+
| Boiler/Steam     | NMOC              | 98.0    | 96-99+   | D        |
| Turbine          |                   |         |          |          |
|                  |                   |         |          |          |
| \(50100423\)     |                   |         |          |          |
|                  |                   |         |          |          |
| Flare^c^         |                   |         |          |          |
|                  |                   |         |          |          |
| \(50100410\)     |                   |         |          |          |
|                  |                   |         |          |          |
| \(50300601\)     |                   |         |          |          |
+------------------+-------------------+---------+----------+----------+
|                  | Halogenated       | 99.6    | 87-99+   | D        |
|                  | Species           |         |          |          |
+------------------+-------------------+---------+----------+----------+
|                  | Non-Halogenated   | 99.8    | 67-99+   | D        |
|                  | Species           |         |          |          |
+------------------+-------------------+---------+----------+----------+
|                  |                   |         |          |          |
+------------------+-------------------+---------+----------+----------+
|                  | NMOC              | 99.2    | 90-99+   | B        |
+------------------+-------------------+---------+----------+----------+
|                  | Halogenated       | 98.0    | 91-99+   | C        |
|                  | Species           |         |          |          |
+------------------+-------------------+---------+----------+----------+
|                  | Non-Halogenated   | 99.7    | 38-99+   | C        |
|                  | Species           |         |          |          |
+------------------+-------------------+---------+----------+----------+
| Gas Turbine      | NMOC              | 94.4    | 90-99+   | E        |
|                  |                   |         |          |          |
| \(50100420\)     | Halogenated       | 99.7    | 98-99+   | E        |
|                  | Species           |         |          |          |
| IC Engine        |                   | 98.2    | 97-99+   | E        |
|                  | Non-Halogenated   |         |          |          |
| \(50100421\)     | Species           | 97.2    | 94-99+   | E        |
|                  |                   |         |          |          |
|                  | NMOC              | 93.0    | 90-99+   | E        |
|                  |                   |         |          |          |
|                  | Halogenated       | 86.1    | 25-99+   | E        |
|                  | Species           |         |          |          |
|                  |                   |         |          |          |
|                  | Non-Halogenated   |         |          |          |
|                  | Species           |         |          |          |
+------------------+-------------------+---------+----------+----------+

^a^ References 10-67. Source Classification Codes in parentheses.

> ^b^ Halogenated species are those containing atoms of chlorine,
> bromine, fluorine, or iodine. For any equipment, the control
> efficiency for mercury should be assumed to be 0. See section 2.4.4.2
> for methods to estimate emissions of SO~2~, CO~2~, and HCl.
>
> ^c^ Where information on equipment was given in the reference, test
> data were taken from enclosed flares. Control efficiencies are assumed
> to be equally representative of open flares.

Table 2.4-4. (Metric Units) EMISSION FACTORS FOR SECONDARY COMPOUNDS

EXITING CONTROL DEVICES^a^

+-------------------+-------------------+----------------+------------+
| Control Device    | Pollutant^b^      | Typical Rate,  | Emission   |
|                   |                   |                | Factor     |
|                   |                   | kg/hr/dscmm    | Rating     |
|                   |                   |                |            |
|                   |                   | Methane        |            |
+-------------------+-------------------+----------------+------------+
| Flare^c^          | Nitrogen dioxide  | 0.039          | C          |
|                   |                   |                |            |
| \(50100410\)      | Carbon monoxide   | 0.72           | C          |
|                   |                   |                |            |
| \(50300601\)      | Particulate       | 0.016          | D          |
|                   | matter            |                |            |
+-------------------+-------------------+----------------+------------+
| IC Engine         | Nitrogen dioxide  | 0.24           | D          |
|                   |                   |                |            |
| \(50100421\)      | Carbon monoxide   | 0.45           | C          |
|                   |                   |                |            |
|                   | Particulate       | 0.046          | E          |
|                   | matter            |                |            |
+-------------------+-------------------+----------------+------------+
| Boiler/Steam      | Nitrogen dioxide  | 0.032          | D          |
| Turbine^d^        |                   |                |            |
|                   | Carbon monoxide   | 5.4 x 10^-3^   | E          |
| \(50100423\)      |                   |                |            |
|                   | Particulate       | 7.9 x 10^-3^   | D          |
|                   | matter            |                |            |
+-------------------+-------------------+----------------+------------+
| Gas Turbine       | Nitrogen dioxide  | 0.083          | D          |
|                   |                   |                |            |
| \(50100420\)      | Carbon monoxide   | 0.22           | E          |
|                   |                   |                |            |
|                   | Particulate       | 0.021          | E          |
|                   | matter            |                |            |
+-------------------+-------------------+----------------+------------+
| ^a^ Source        |                   |                |            |
| Classification    |                   |                |            |
| Codes in          |                   |                |            |
| parentheses.      |                   |                |            |
|                   |                   |                |            |
| ^b^ No data on PM |                   |                |            |
| size              |                   |                |            |
| distributions     |                   |                |            |
| were available,   |                   |                |            |
| however for other |                   |                |            |
| gas-fired         |                   |                |            |
| combustion        |                   |                |            |
| sources, most of  |                   |                |            |
| the particulate   |                   |                |            |
| matter is less    |                   |                |            |
| than 2.5 microns  |                   |                |            |
| in diameter.      |                   |                |            |
| Hence, this       |                   |                |            |
| emission factor   |                   |                |            |
| can be used to    |                   |                |            |
| provide estimates |                   |                |            |
| of PM-10 or       |                   |                |            |
| PM-2.5 emissions. |                   |                |            |
| See section       |                   |                |            |
| 2.4.4.2 for       |                   |                |            |
| methods to        |                   |                |            |
| estimate CO~2~,   |                   |                |            |
| SO~2~, and HCl.   |                   |                |            |
|                   |                   |                |            |
| ^c^ Where         |                   |                |            |
| information on    |                   |                |            |
| equipment was     |                   |                |            |
| given in the      |                   |                |            |
| reference, test   |                   |                |            |
| data were taken   |                   |                |            |
| from enclosed     |                   |                |            |
| flares. Control   |                   |                |            |
| efficiencies are  |                   |                |            |
| assumed to be     |                   |                |            |
| equally           |                   |                |            |
| representative of |                   |                |            |
| open flares.      |                   |                |            |
|                   |                   |                |            |
| ^d^ All source    |                   |                |            |
| tests were        |                   |                |            |
| conducted on      |                   |                |            |
| boilers, however  |                   |                |            |
| emission factors  |                   |                |            |
| should also be    |                   |                |            |
| representative of |                   |                |            |
| steam turbines.   |                   |                |            |
| Emission factors  |                   |                |            |
| are               |                   |                |            |
| representative of |                   |                |            |
| boilers equipped  |                   |                |            |
| with low-NO~x~    |                   |                |            |
| burners and flue  |                   |                |            |
| gas               |                   |                |            |
| recirculation. No |                   |                |            |
| data were         |                   |                |            |
| available for     |                   |                |            |
| uncontrolled      |                   |                |            |
| NO~x~ emissions.  |                   |                |            |
+-------------------+-------------------+----------------+------------+

Table 2.4-5. (English Units) EMISSION RATES FOR SECONDARY COMPOUNDS

EXITING CONTROL DEVICES^a^

+---------------------+-------------------+--------------+-----------+
| Control Device      | Pollutant^b^      | Typical      | Emission  |
|                     |                   | Rate,        | Factor    |
|                     |                   |              | Rating    |
|                     |                   | lb/hr/dscfm  |           |
|                     |                   |              |           |
|                     |                   | Methane      |           |
+---------------------+-------------------+--------------+-----------+
| Flare^c^            | Nitrogen dioxide  | 2.4 x 10^-3^ | C         |
|                     |                   |              |           |
| \(50100410\)        | Carbon monoxide   | 0.045        | C         |
|                     |                   |              |           |
| \(50300601\)        | Particulate       | 1.0 x 10^-3^ | D         |
|                     | matter            |              |           |
+---------------------+-------------------+--------------+-----------+
| IC Engine           | Nitrogen dioxide  | 0.015        | D         |
|                     |                   |              |           |
| \(50100421\)        | Carbon monoxide   | 0.028        | C         |
|                     |                   |              |           |
|                     | Particulate       | 2.9 x 10^-3^ | E         |
|                     | matter            |              |           |
+---------------------+-------------------+--------------+-----------+
| Boiler/Steam        | Nitrogen dioxide  | 2.0 x 10^-3^ | E         |
| Turbine^d^          |                   |              |           |
|                     | Carbon monoxide   | 3.4 x 10^-4^ | E         |
| \(50100423\)        |                   |              |           |
|                     | Particulate       | 4.9 x 10^-4^ | E         |
|                     | matter            |              |           |
+---------------------+-------------------+--------------+-----------+
| Gas Turbine         | Nitrogen dioxide  | 5.2 x 10^-3^ | D         |
|                     |                   |              |           |
| \(50100420\)        | Carbon monoxide   | 0.014        | D         |
|                     |                   |              |           |
|                     | Particulate       | 1.3 x 10^-3^ | E         |
|                     | matter            |              |           |
+---------------------+-------------------+--------------+-----------+
| ^a^ Source          |                   |              |           |
| Classification      |                   |              |           |
| Codes in            |                   |              |           |
| parentheses.        |                   |              |           |
|                     |                   |              |           |
| ^b^ Based on data   |                   |              |           |
| for other           |                   |              |           |
| combustion sources, |                   |              |           |
| most of the         |                   |              |           |
| particulate matter  |                   |              |           |
| will be less than   |                   |              |           |
| 2.5 microns in      |                   |              |           |
| diameter. Hence,    |                   |              |           |
| this emission rate  |                   |              |           |
| can be used to      |                   |              |           |
| provide estimates   |                   |              |           |
| of PM-10 or PM-2.5  |                   |              |           |
| emissions. See      |                   |              |           |
| section 2.4.4.2 for |                   |              |           |
| methods to estimate |                   |              |           |
| CO~2~, SO~2~, and   |                   |              |           |
| HCl.                |                   |              |           |
|                     |                   |              |           |
| ^c^ Where           |                   |              |           |
| information on      |                   |              |           |
| equipment was given |                   |              |           |
| in the reference,   |                   |              |           |
| test data were      |                   |              |           |
| taken from enclosed |                   |              |           |
| flares. Control     |                   |              |           |
| efficiencies are    |                   |              |           |
| assumed to be       |                   |              |           |
| equally             |                   |              |           |
| representative of   |                   |              |           |
| open flares.        |                   |              |           |
|                     |                   |              |           |
| ^d^ All source      |                   |              |           |
| tests were          |                   |              |           |
| conducted on        |                   |              |           |
| boilers, however    |                   |              |           |
| emission factors    |                   |              |           |
| should also be      |                   |              |           |
| representative of   |                   |              |           |
| steam turbines.     |                   |              |           |
| Emission factors    |                   |              |           |
| are representative  |                   |              |           |
| of boilers equipped |                   |              |           |
| with low-NO~x~      |                   |              |           |
| burners and flue    |                   |              |           |
| gas recirculation.  |                   |              |           |
| No data were        |                   |              |           |
| available for       |                   |              |           |
| uncontrolled NO~x~  |                   |              |           |
| emissions.          |                   |              |           |
+---------------------+-------------------+--------------+-----------+

References for Section 2.4

1\. \"Criteria for Municipal Solid Waste Landfills,\" 40 CFR Part 258,
Volume 56, No. 196, October 9, 1991.

2\. *Air Emissions from Municipal Solid Waste Landfills - Background
Information for Proposed Standards and Guidelines,* Office of Air
Quality Planning and Standards, EPA-450/3-90-011a, Chapters 3 and 4, U.
S. Environmental Protection Agency, Research Triangle Park, NC, March
1991.

3\. *Characterization of Municipal Solid Waste in the United States:
1992 Update,* Office of Solid Waste, EPA-530-R-92-019, U. S.
Environmental Protection Agency, Washington, DC, NTIS No. PB92-207-166,
July 1992.

4\. Eastern Research Group, Inc., *List of Municipal Solid Waste
Landfills*, Prepared for the U. S. Environmental Protection Agency,
Office of Solid Waste, Municipal and Industrial Solid Waste Division,
Washington, DC, September 1992.

5\. *Suggested Control Measures for Landfill Gas Emissions,* State of
California Air Resources Board, Stationary Source Division, Sacramento,
CA, August 1990.

6\. \"Standards of Performance for New Stationary Sources and Guidelines
for Control of Existing Sources: Municipal Solid Waste Landfills;
Proposed Rule, Guideline, and Notice of Public Hearing,\" 40 CFR
Parts 51, 52, and 60, Vol. 56, No. 104, May 30, 1991.

7\. S.W. Zison, Landfill Gas Production Curves: Myth Versus Reality,
Pacific Energy, City of Commerce, CA, \[Unpublished\]

8\. R.L. Peer, et al., Memorandum *Methodology Used to Revise the Model
Inputs in the Municipal Solid Waste Landfills Input Data Bases
(Revised)*, to the Municipal Solid Waste Landfills Docket No. A-88-09,
April 28, 1993.

9\. A.R. Chowdhury, *Emissions from a Landfill Gas-Fired
Turbine/Generator Set, Source Test Report C-84-33*, Los Angeles County
Sanitation District, South Coast Air Quality Management District, June
28, 1984.

10\. Engineering-Science, Inc., *Report of Stack Testing at County
Sanitation District Los Angeles Puente Hills Landfill*, Los Angeles
County Sanitation District, August 15, 1984.

11\. J.R. Manker, *Vinyl Chloride (and Other Organic Compounds) Content
of Landfill Gas Vented to an Inoperative Flare, Source Test Report
84-496*, David Price Company, South Coast Air Quality Management
District, November 30, 1984.

12\. S. Mainoff, *Landfill Gas Composition, Source Test Report 85-102*,
Bradley Pit Landfill, South Coast Air Quality Management District,
May 22, 1985.

13\. J. Littman, *Vinyl Chloride and Other Selected Compounds Present in
A Landfill Gas Collection System Prior to and after Flaring, Source Test
Report 85-369*, Los Angeles County Sanitation District, South Coast Air
Quality Management District, October 9, 1985.

14\. W.A. Nakagawa, *Emissions from a Landfill Exhausting Through a
Flare System, Source Test Report 85-461*, Operating Industries, South
Coast Air Quality Management District, October 14, 1985.

15\. S. Marinoff, *Emissions from a Landfill Gas Collection System,
Source Test Report 85-511*. Sheldon Street Landfill, South Coast Air
Quality Management District, December 9, 1985.

16\. W.A. Nakagawa, *Vinyl Chloride and Other Selected Compounds Present
in a Landfill Gas Collection System Prior to and after Flaring, Source
Test Report 85-592*, Mission Canyon Landfill, Los Angeles County
Sanitation District, South Coast Air Quality Management District,
January 16, 1986.

17\. California Air Resources Board, *Evaluation Test on a Landfill
Gas-Fired Flare at the BKK Landfill Facility*, West Covina, CA,
ARB-SS-87-09, July 1986.

18\. S. Marinoff, *Gaseous Composition from a Landfill Gas Collection
System and Flare, Source Test Report 86-0342*, Syufy Enterprises, South
Coast Air Quality Management District, August 21, 1986.

19\. *Analytical Laboratory Report for Source Test*, Azusa Land
Reclamation, June 30, 1983, South Coast Air Quality Management District.

20\. J.R. Manker, *Source Test Report C-84-202*, Bradley Pit Landfill,
South Coast Air Quality Management District, May 25, 1984.

21\. S. Marinoff, *Source Test Report 84-315*, Puente Hills Landfill,
South Coast Air Quality Management District, February 6, 1985.

22\. P.P. Chavez, *Source Test Report 84-596*, Bradley Pit Landfill,
South Coast Air Quality Management District, March 11, 1985.

23\. S. Marinoff, *Source Test Report 84-373*, Los Angeles By-Products,
South Coast air Quality Management District, March 27, 1985.

24\. J. Littman, *Source Test Report 85-403*, Palos Verdes Landfill,
South Coast Air Quality Management District, September 25, 1985.

25\. S. Marinoff, *Source Test Report 86-0234*, Pacific Lighting Energy
Systems, South Coast Air Quality Management District, July 16, 1986.

26\. South Coast Air Quality Management District, *Evaluation Test on a
Landfill Gas-Fired Flare at the Los Angeles County Sanitation
District\'s Puente Hills Landfill Facility*, \[ARB/SS-87-06\],
Sacramento, CA, July 1986.

27\. D.L. Campbell, et al., *Analysis of Factors Affecting Methane Gas
Recovery from Six Landfills*, Air and Energy Engineering Research
Laboratory, EPA-600/2-91-055, U. S. Environmental Protection Agency,
Research Triangle Park, NC, September 1991.

28\. Browning-Ferris Industries, Source Test Report, Lyon Development
Landfill, August 21, 1990.

29\. X.V. Via, *Source Test Report*, Browning-Ferris Industries, Azusa
Landfill.

30\. M. Nourot, *Gaseous Composition from a Landfill Gas Collection
System and Flare Outlet*. Laidlaw Gas Recovery Systems, to J.R. Farmer,
OAQPS:ESD, December 8, 1987.

31\. D.A. Stringham and W.H. Wolfe, *Waste Management of North America,
Inc.*, to J.R. Farmer, OAQPS:ESD, January 29, 1988, Response to Section
114 questionnaire.

32\. V. Espinosa, *Source Test Report 87-0318*, Los Angeles County
Sanitation District Calabasas Landfill, South Coast Air Quality
Management District, December 16, 1987.

33\. C.S. Bhatt, *Source Test Report 87-0329*, Los Angeles County
Sanitation District, Scholl Canyon Landfill, South Coast Air Quality
Management District, December 4, 1987.

34\. V. Espinosa, *Source Test Report 87-0391*, Puente Hills Landfill,
South Coast Air Quality Management District, February 5, 1988.

35\. V. Espinosa, *Source Test Report 87-0376*, Palos Verdes Landfill,
South Coast Air Quality Management District, February 9, 1987.

36\. Bay Area Air Quality Management District, *Landfill Gas
Characterization*, Oakland, CA, 1988.

37\. Steiner Environmental, Inc., *Emission Testing at BFI\'s Arbor
Hills Landfill, Northville, Michigan*, September 22 through 25, 1992,
Bakersfield, CA, December 1992.

38\. PEI Associates, Inc., *Emission Test Report - Performance
Evaluation Landfill-Gas Enclosed Flare, Browning Ferris Industries*,
Chicopee, MA, 1990.

39\. Kleinfelder Inc., *Source Test Report Boiler and Flare Systems*,
Prepared for Laidlaw Gas Recovery Systems, Coyote Canyon Landfill,
Diamond Bar, CA, 1991.

40\. Bay Area Air Quality Management District, *McGill Flare Destruction
Efficiency Test Report for Landfill Gas at the Durham Road Landfill*,
Oakland, CA, 1988.

41\. San Diego Air Pollution Control District, *Solid Waste Assessment
for Otay Valley/Annex Landfill*. San Diego, CA, December 1988.

42\. PEI Associates, Inc., *Emission Test Report - Performance
Evaluation Landfill Gas Enclosed Flare*, Rockingham, VT, September 1990.

43\. Browning-Ferris Industries, *Gas Flare Emissions Source Test for
Sunshine Canyon Landfill.* Sylmar, CA, 1991.

44\. Scott Environmental Technology, *Methane and Nonmethane Organic
Destruction Efficiency Tests of an Enclosed Landfill Gas Flare*, April
1992.

45\. BCM Engineers, Planners, Scientists and Laboratory Services, *Air
Pollution Emission Evaluation Report for Ground Flare at Browning Ferris
Industries Greentree Landfill, Kersey, Pennsylvania*. Pittsburgh, PA,
May 1992.

46\. EnvironMETeo Services Inc., *Stack Emissions Test Report for Ameron
Kapaa Quarry,* Waipahu, HI, January 1994.

47\. Waukesha Pearce Industries, Inc., *Report of Emission Levels and
Fuel Economies for Eight Waukesha 12V-AT25GL Units Located at the
Johnston, Rhode Island Central Landfill,* Houston TX, July 19, 1991.

48\. Mostardi-Platt Associates, Inc., *Gaseous Emission Study Performed
for Waste Management of North America, Inc., CID Environmental Complex
Gas Recovery Facility, August 8, 1989.* Chicago, IL, August 1989.

49\. Mostardi-Platt Associates, Inc., *Gaseous Emission Study Performed
for Waste Management of North America, Inc., at the CID Environmental
Complex Gas Recovery Facility, July 12-14, 1989*. Chicago, IL, July
1989.

50\. Browning-Ferris Gas Services, Inc., *Final Report for Emissions
Compliance Testing of One Waukesha Engine Generator*, Chicopee, MA,
February 1994.

51\. Browning-Ferris Gas Services, Inc., *Final Report for Emissions
Compliance Testing of Three Waukesha Engine Generators*, Richmond, VA,
February 1994.

52\. South Coast Environmental Company (SCEC), *Emission Factors for
Landfill Gas Flares at the Arizona Street Landfill*, Prepared for the
San Diego Air Pollution Control District, San Diego, CA, November 1992.

53\. Carnot, *Emission Tests on the Puente Hills Energy from Landfill
Gas (PERG) Facility - Unit 400, September 1993*, Prepared for County
Sanitation Districts of Los Angeles County, Tustin, CA, November 1993.

54\. Pape & Steiner Environmental Services, *Compliance Testing for
Spadra Landfill Gas-to-Energy Plant, July 25 and 26, 1990*, Bakersfield,
CA, November 1990.

55\. AB2588 Source Test Report for Oxnard Landfill, July 23-27, 1990, by
Petro Chem Environmental Services, Inc., for Pacific Energy Systems,
Commerce, CA, October 1990.

56\. AB2588 Source Test Report for Oxnard Landfill, October 16, 1990, by
Petro Chem Environmental Services, Inc., for Pacific Energy Systems,
Commerce, CA, November 1990.

57\. Engineering Source Test Report for Oxnard Landfill, December 20,
1990, by Petro Chem Environmental Services, Inc., for Pacific Energy
Systems, Commerce, CA, January 1991.

58\. AB2588 Emissions Inventory Report for the Salinas Crazy Horse
Canyon Landfill, Pacific Energy, Commerce, CA, October 1990.

59\. Newby Island Plant 2 Site IC Engine\'s Emission Test, February 7-8,
1990, Laidlaw Gas Recovery Systems, Newark, CA, February 1990.

60\. Landfill Methane Recovery Part II: Gas Characterization, Final
Report, Gas Research Institute, December 1982.

61\. Letter from J.D. Thornton, Minnesota Pollution Control Agency, to
R. Myers, U.S. EPA, February 1, 1996.

62\. Letter and attached documents from M. Sauers, GSF Energy, to S.
Thorneloe, U.S. EPA, May 29, 1996.

63\. Landfill Gas Particulate and Metals Concentration and Flow Rate,
Mountaingate Landfill Gas Recovery Plant, Horizon Air Measurement
Services, prepared for GSF Energy, Inc., May 1992.

64\. Landfill Gas Engine Exhaust Emissions Test Report in Support of
Modification to Existing IC Engine Permit at Bakersfield Landfill Unit
#1, Pacific Energy Services, December 4, 1990.

65\. Addendum to Source Test Report for Superior Engine #1 at Otay
Landfill, Pacific Energy Services, April 2, 1991.

66\. Source Test Report 88-0075 of Emissions from an Internal Combustion
Engine Fueled by Landfill Gas, Penrose Landfill, Pacific Energy Lighting
Systems, South Coast Air Quality Management District, February 24, 1988.

67\. Source Test Report 88-0096 of Emissions from an Internal Combustion
Engine Fueled by Landfill Gas, Toyon Canyon Landfill, Pacific Energy
Lighting Systems, March 8, 1988.

68\. Letter and attached documents from C. Nesbitt, Los Angeles County
Sanitation Districts, to K. Brust, E.H. Pechan and Associates, Inc.,
December 6, 1996.

69\. Determination of Landfill Gas Composition and Pollutant Emission
Rates at Fresh Kills Landfill, revised Final Report, Radian Corporation,
prepared for U.S. EPA, November 10, 1995.

70\. Advanced Technology Systems, Inc., *Report on Determination of
Enclosed Landfill Gas Flare Performance*, Prepared for Y & S
Maintenance, Inc., February 1995.

71\. Chester Environmental, *Report on Ground Flare Emissions Test
Results*, Prepared for Seneca Landfill, Inc., October 1993.

72\. Smith Environmental Technologies Corporation, *Compliance Emission
Determination of the Enclosed Landfill Gas Flare and Leachate Treatment
Process Vents*, Prepared for Clinton County Solid Waste Authority, April
1996.

73\. AirRecon®, Division of RECON Environmental Corp., *Compliance Stack
Test Report for the Landfill Gas FLare Inlet & Outlet at Bethlehem
Landfill*, Prepared for LFG Specialties Inc., December 3, 1996.

74\. ROJAC Environmental Services, Inc., *Compliance Test Report,
Hartford Landfill Flare Emissions Test Program*, November 19, 1993.

75\. Normandeau Associates, Inc., *Emissions Testing of a Landfill Gas
Flare at Contra Costa Landfill, Antioch, California, March 22, 1994 and
April 22, 1994*, May 17, 1994.

76\. Roe, S.M., et. al., *Methodologies for Quantifying Pollution
Prevention Benefits from Landfill Gas Control and Utilization*, Prepared
for U.S. EPA, Office of Air and Radiation, Air and Energy Engineering
Laboratory, EPA-600/R-95-089, July 1995.