User’s Guide for Estimating Emissions from Municipal Solid Waste Using the State Inventory Tool January 2022


User's Guide for Estimating
Emissions from Municipal
Solid Waste Using the State
Inventory Tool

January 2022



Prepared by:
ICF

Prepared for:

State Energy and Environment Program,
U.S. Environmental Protection Agency

This section of the User's Guide provides instruction on using the Municipal Solid Waste
module of the State Inventory Tool (SIT), and describes the methodology used for
estimating greenhouse gas (GHG) emissions from municipal solid waste management at the
state level.

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Module 9 - Municipal Solid Waste Module

January 2022

Table of Contents

1.1	Getting Started	2

1.2	Module Overview	4

1.2.1	Data Requirements	6

1.2.2	Tool Layout	6

1.3	Methodology	7

1.4	Uncertainty	18

1.5	References	18

State Greenhouse Gas Inventory Tool User's Guide for the Municipal Solid Waste Module

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1.1 Getting Started

The Municipal Solid Waste module was developed using Microsoft® Excel 2000. While the
module will operate with older versions of Excel, it functions best with Excel 2000 or later.
If you are using Excel 2007 or later, instructions for opening the module will vary as
outlined in the Excel basics below. Some of the Excel basics are outlined in the sections
below. Before you use the Municipal Solid Waste module, make sure your computer meets
the system requirements. In order to install and run the Municipal Solid Waste module, you
must have:

• IBM-PC compatible computer with the Windows 95 operating system or later;

• Microsoft® Excel 1997 or later, with calculation set to automatic and macros
enabled;

• Hard drive with at least 20MB free; and

• Monitor display setting of 800 x 600 or greater.

Microsoft Excel Settings

Excel 2003 and Earlier: For the SIT modules to function properly, Excel must be set to
automatic calculation. To check this setting, launch Microsoft Excel before opening the
Municipal Solid Waste module. Go to the Tools menu and select "Options..." Click on the
"Calculations" tab and make sure that the radio button next to "Automatic" is selected, and
then click on "OK" to close the window. The security settings (discussed next) can also be
adjusted at this time.

Excel 2007 and Later: For the SIT modules to function properly, Excel must be set to
automatic calculation. Go to the Formulas ribbon and select "Calculation Options." Make
sure that the box next to the "Automatic" option is checked from the pop-up menu.

Microsoft Excel Security

Excel 2003 and Earlier: Because the SIT employs macros, you must have Excel security
set to medium (recommended) or low (not recommended). To change this setting, launch
Microsoft Excel before opening the Municipal Solid Waste module. Once in Excel, go to the
Tools menu, click on the Macro sub-menu, and then select "Security" (see Figure 1). The
Security pop-up box will appear. Click on the "Security Level" tab and select medium.

When set to high, macros are automatically disabled; when set to medium, Excel will give
you the choice to enable macros; when set to low, macros are always enabled.

When Excel security is set to medium, users are asked upon opening the module whether to
enable macros. Macros must be enabled in order for the Municipal Solid Waste module to
work. Once they are enabled, the module will open to the control worksheet. A message
box will appear welcoming the user to the module. Clicking on the "x" in the upper-right-
hand corner of the message box will close it.

Excel 2007 and Later: If Excel's security settings are set at the default level a Security
Warning appears above the formula box in Excel when the Municipal Solid Waste module is
initially opened. The Security Warning lets the user know that some active content from the
spreadsheet has been disabled, meaning that Excel has prevented the macros in the
spreadsheet from functioning. Because SIT needs macros in order to function properly, the
user must click the "Options" button in the security message and then select, "Enable this

State Greenhouse Gas Inventory Tool User's Guide for the Municipal Solid Waste Module

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content" in the pop-up box. Enabling the macro content for the SIT in this way only enables
macros temporarily in Excel but does not change the macro security settings. Once macros
are enabled, a message box will appear welcoming the user to module. Click on the "x" in
the upper right-hand corner to close the message box.

If the Security Warning does not appear when the module is first opened, it may be
necessary to change the security settings for macros. To change the setting, first exit out
of the Municipal Solid Waste module and re-launch Microsoft Excel before opening the
Municipal Solid Waste module. Next, click on the Microsoft Excel icon in the top left of the
screen. Scroll to the bottom of the menu and select the "Excel Options" button to the right
of the main menu. When the Excel Options box appears, select "Trust Center" in left hand
menu of the box. Next, click the gray "Trust Center Settings" button. When the Trust
Center options box appears, click "Macro Settings" in the left-hand menu and select "Disable
all macros with notification." Once the security level has been adjusted, open the
Stationary Combustion module and enable macros in the manner described in the preceding
paragraph.

Viewing and Printing Data and Results

The Municipal Solid Waste module contains some features to allow users to adjust the
screen view and the appearance of the worksheets when they are printed. Once a module
has been opened, you can adjust the zoom by going to the Module Options Menu, and either
typing in a zoom percentage or selecting one from the drop-down menu. In addition, data
may not all appear on a single screen within each worksheet; if not, you may need to scroll
up or down to view additional information.

You may also adjust the print margins of the worksheets to ensure that desired portions of
the Municipal Solid Waste module are printed. To do so, go to the File menu, and then
select "Print Preview." Click on "Page Break Preview" and drag the blue lines to the desired
positions (see Figure 2). To print this view, go to the File menu, and click "Print." To return
to the normal view, go to the File menu, click "Print Preview," and then click "Normal View."

Figure 1. Changing Security Settings

D Microsoft Excel - Bookl

liSj File Edit

View Insert

Format

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Spelling.., F7

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Research,,. Alt+Click

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Error Checking...

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Share Workbook...

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Compare and Merge Workbooks..,

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Goal Seek...

Scenarios...

Formula Auditing ~

| Macro ~ |

Macros...

Alt+F8

Add-Ins...

RprnrH Mrw Mflrrn...

1 "

AutoCorrect Options,,,

Security,,,

Customize...

1 Visual Basic Editor

Alt+Fll

Options.,,

........

Alt+Shift+Fll

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~ Stale Inventory Tool Municipal Solid Waste Module

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:igure 2. Adjusting Print Margins

State Inventory Tool - Municipal Solid Waste Module

imite asfli Ma atsMt,

Choose a State

Describe the type of

Drag cursor
to resize page

all years 1961 through 20CC.

ind nalior^l nei capita unarming rates, j

emissions from MSW landfills In Connecticut.

State Greenhouse Gas Inventory Tool User's Guide for the Municipal Solid Waste Module

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1.2 Module Overview

This User's Guide accompanies and explains the Municipal Solid Waste module of the SIT.
The SIT was developed in conjunction with EPA's Emissions Inventory Improvement
Program (EIIP). Prior to the development of the SIT, EPA developed the States Workbook
for estimating greenhouse gas emissions. In 1998, EPA revisited the States Workbook and
expanded it to follow the format of EIIP guidance documents for criteria air pollutants. The
result was a comprehensive, stepwise approach to estimating greenhouse gas emissions at
the state level. This detailed methodology was appreciated by states with the capacity to
devote considerable time and resources to the development of emission inventories. For
other states, the EIIP guidance was overwhelming and impractical for them to follow from
scratch. EPA recognized the resource constraints facing the states and developed the SIT.
The ten modules of the SIT corresponded to the EIIP chapters and attempted to automate
the steps states would need to take in developing their own emission estimates in a manner
that was consistent with prevailing national and state guidelines.

Because most state inventories developed today rely heavily on the tools, User's Guides
have been developed for each of the SIT modules. These User's Guides contain the most
up-to-date methodologies that are, for the most part, consistent with the Inventory of U.S.
Greenhouse Gas Emissions and Sinks. Volume VIII of the EIIP guidance is a historical
document that was last updated in August 2004, and while these documents can be a
valuable reference, they contain outdated emissions factors and, in some cases, outdated
methodologies. States can refer to Volume VIII of the EIIP guidance documents if they are
interested in obtaining additional information not found in the SIT or the companion User's
Guide.

The Municipal Solid Waste module
calculates methane (Cl-U) emissions
from landfilling of municipal solid
waste (MSW) and carbon dioxide
(CO2) and nitrous oxide (N2O)
emissions from the combustion of
MSW. While the module provides
default data for most inputs, if you have access to more comprehensive data sources, they
should be used in place of the default data (see Box 1 for suggestions of possible data
sources). If using outside data sources, or for a more thorough understanding of the tool,
please refer to the following Methodology section for data requirements and methodology.

In landfills, CH4 and CO2 are produced from anaerobic decomposition of organic matter by
methanogenic bacteria. Organic waste first decomposes aerobically (in the presence of
oxygen) and is then decomposed by anaerobic non-methanogenic bacteria, which convert
organic material to simpler forms like cellulose, amino acids, sugars, and fats. These simple
substances are further broken down to gases and short-chain organic compounds (H2, CO2,
CH3COOH, HCOOH, and CH3OH), which support the growth of methanogenic bacteria. The
bacteria further metabolize these fermentation products into stabilized organic materials
and "biogas," which consists of approximately 50 percent CO2 and 50 percent CH4 by
volume. Additionally, some landfills flare recovered landfill gas, which converts the CH4
portion of the gas to CO2. There are also some landfills that collect and burn landfill gas for
electricity production or other energy uses (known as landfill-gas-to-energy projects, or
LFGTE), which are treated similarly to landfills that flare their gas.

Box 1: State Solid Waste Data Sources

In-state sources, such as state departments of
environmental protection, should be consulted first.
Otherwise, default data provided by the Municipal Solid
Waste module may be used.

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Neither the CO2 emitted directly as biogas nor the CO2 emitted from combusting ChU at
flares is counted as an anthropogenic greenhouse gas (GHG) emission. The source of the
CO2 is primarily the decomposition of organic materials derived from biomass sources (e.g.,
crops, forests), and in the United States these sources are grown and harvested on a
sustainable basis. Sustainable harvesting implies that photosynthesis (which removes CO2
from the atmosphere) is equal to decomposition (which adds CO2 to the atmosphere).

Waste combustion emits both CO2 and N2O. CO2 is produced from the oxidation of organic
materials in waste, such as paper, food scraps, yard trimmings, and plastic. As with CO2
from biogas and oxidation of ChU, CO2 emissions from biogenic sources (e.g., paper and
food scraps) are not counted in GHG inventories because they simply return CO2 that plants
previously absorbed through photosynthesis to the atmosphere. However, some CO2 is
from nonbiogenic sources (e.g., plastic and rubber made from petroleum), and is thus
counted in GHG emission inventories. N2O is produced at the high temperature found in
waste combustors by the combination of nitrogen (both nitrogen contained in the waste and
nitrogen gas in the air) and oxygen gas in the air.

Users should also note that an additional waste-related greenhouse gas sink, carbon storage
from landfilled yard trimmings and food scraps, is accounted for in the Land-Use Change
and Forestry module of the SIT.

State Greenhouse Gas Inventory Tool User's Guide for the Municipal Solid Waste Module

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1.2.1 Data Requirements

To calculate GHG emissions from municipal solid waste management, the data listed in
Table 1 are required inputs (again, note that defaults are available for most of these data).

Table 1. Required Data Inputs for the Municipal Solid Waste Module

Solid Waste Sectors

Input Data

Landfills

Amount of MSW landfilled in state from 1960 through the present OR
from 1990 through the present (short tons)

State population data, 1960 through the present

Amount of CH4 flared/recovered at landfills (short tons)

Industrial landfill CH4 emissions, as a percent of MSW landfill emissions

Percent of landfill CH4 oxidized at the landfill surface (oxidation factor)

Waste Combustion

Fraction of plastics, synthetic rubber, and synthetic fiber that is oxidized
in a combustion facility

Amount of MSW combusted for 1990 through the present (short tons)

Plastic Combustion

Polyethylene terephthalate (PET) as a proportion of all MSW discards

High-density polyethylene (HDPE) as a proportion of all MSW discards

Polyvinyl chloride (PVC) as a proportion of all MSW discards

Low-density/linear low-density polyethylene (LDPE/LLDPE) as a proportion
of all MSW discards

Polypropylene (PP) as a proportion of all MSW discards
Polystyrene (PS) as a proportion of all MSW discards
Other plastic as a proportion of all MSW discards

Synthetic Rubber
Combustion

Synthetic rubber durables as a proportion of all MSW discards

Synthetic rubber clothing and footwear as a proportion of all MSW
discards

Other synthetic rubber non-durables as a proportion of all MSW discards

Synthetic rubber containers and packaging as a proportion of all MSW
discards

Synthetic Fiber
Combustion

Synthetic fiber as a proportion of all MSW discards

1.2.2 Tool Layout

Because the methodology of the Municipal Solid Waste module is complex, it is important to
understand the module's overall design. The layout of the Municipal Solid Waste module
and the purpose of its worksheets are presented in Figure 3.

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Figure 3. Flow of Information in the Municipal Solid Waste Module

Control Worksheet

1.	Select a State

2.	Describe and Enter Disposal Data

3.	Enter Population Data

4.	View preliminary CH4 emissions from landfills }

5.	Adjust CH4 emissions for flaring

6.	Adjust for CH4 recovered at LFGTE Plants

7.	Estimate CH4 generated at industrial landfills

8.	Select landfill CH4 oxidation factor

9.	Fill in variables for waste combustion

10. -14. Complete Combustion Calculation Worksheets



15.	View Summary Data

16.	Export Data

Data Entry and Calculation Worksheets

2.	State Disposal Data

Enter data 1960-Present, 1990-Present, or Default

3.	State Population Data
Enter default or user-entered data

4.	First Order Decay Model Calculation
View calculations of CH4 emissions

5.	CH4 Avoided from Flaring
Enter default or user-entered data

6.	CH4 Avoided from LFGTE

-- Enter default or user-entered data

10.	C02 from Plastics Combustion
1 Enter data on plastics as a proportion of all waste

11.	C02 from Synthetic Rubber Combustion
I Enter data on synthetic rubber as a proportion of all waste

12.	C02 from Synthetic Fiber Combustion
I Enter data on synthetic fiber as a proportion of all waste

13.	N20 Emissions from MSW Combustion
I View calculations of N20 emissions

14.	CH4 Emissions from MSW Combustion
s View calculations of CH4 emissions

Summary Data
I Presented in table and graphical formats in MMTC02E
Uncertainty

Review information on uncertainty associated with the default data

1.3 Methodology

This section provides a guide to using the Municipal Solid Waste module of the SIT to
estimate GHG emissions from municipal solid waste management. The two sectors within
the Municipal Solid Waste module, landfills and combustion, are treated separately. Steps 4
through 8 address the estimation of landfill ChU, while Step 9 deals with combustion.

The following steps are involved in estimating emissions using the Municipal Solid Waste
module: (1) select a state; (2) describe and enter state disposal information; (3) enter
population data; (4) view preliminary ChU emissions from landfills; (5) adjust ChU emissions
for the amount that is flared; (6) adjust for the amount of ChU recovered at landfill-gas-to-
energy plants; (7) estimate ChU generated at industrial landfills; (8) select landfill ChU
oxidation factor; (9) fill in the variables used for waste combustion; (10) complete the CO2
from synthetic rubber combustion worksheet; (11) complete the CO2 from synthetic fiber
combustion worksheet; (12) complete the CO2 from the combustion of synthetic fibers
worksheet; (13) review estimates on the N2O from MSW combustion worksheet; (14) review
estimates on the ChU from MSW combustion worksheet; (15) review summary information;
and (16) export data. Most of these steps take place on the control worksheet. The
Municipal Solid Waste module will automatically calculate emissions after you make choices
on the control worksheet and enter the required data on the individual sector worksheets.
The tool provides default sector data for most sectors.

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Step (1) Select a State

To begin, select the state you are interested in evaluating. By selecting a state, the rest of
the tool will automatically reset to reflect the appropriate state default data and
assumptions for use in subsequent steps of the tool.

Step (2) Describe and Enter State Disposal Information

On the control worksheet, select the radio button that corresponds to the data you would
like to use as shown in Figure 4. There are three data options for entering waste disposal
data:

Option 1: If you have state-specific information on waste disposal from 1960 to the
present, then no further disposal or population (see Step (3)) data are needed.

Option 2: If you have state data on waste disposal for 1990 through the present, but
not dating back to 1960, the module will estimate waste disposal using historical
population data and national per capita landfilling rates.

Option 3: If do not have state-specific disposal data, you may use the default
disposal data already loaded into the module. Default disposal data were estimated
by allocating national waste disposal data (U.S. EPA 2020) to the state level on the
basis of a state's historical population (U.S. Census 2020).

Clicking either of the first two user-entered data options will take you directly to a disposal
data entry worksheet where you will enter annual state disposal into the yellow input cells.
If you choose to use the available default disposal data provided in the module, you may
navigate to the data-entry worksheet using the gray "View / Enter Data" arrow to the right
of the selection buttons.

The uncertainty associated with the three state disposal options varies. The range of
uncertainty represented by these three options is highly variable. Option 1 is preferable, if
the state-specific data entered into the module is well-documented and comprehensive.
Option 2 attempts to leverage near-term historical data and to scale national information on
per capita disposal, state population, and national population information to back cast waste
disposal estimates. This approach draws on several assumptions, namely that per capita
generation in the state is the same as per capita generation at the national level. Option 3
has the least reliance on state information, making it the easiest, but potentially the least
certain of the three options.

The module uses a statistical model, known as a first order decay (FOD) model, to calculate
landfill emissions. In the FOD model, the Chk emission rate is a function of the quantity of
waste deposited in landfills (in short tons) over the previous 30 years.

State Greenhouse Gas Inventory Tool User's Guide for the Municipal Solid Waste Module

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Figure 4. Example of Steps 1 through 4 on the Control Worksheet

1 D State Inventory Tool - Municipal Solid Waste Module

|' File Edit Module Options

^pe a question for help £ _ X |

State Inventory Tool - Municipal Solid Waste Module

This tool estimates state methane emissions from municipal solid waste dis| Choose a State
it is recommended that you use your own data or review the default dat

|Consult EIIP Guidance |
Reset ALL!

1. Choose a State fietects^itatTT '

This step is very important- it seiects the correct default variables for your state.

Select button corresponding to the
type of disposal data you have...

2. Describe and enter the type of state disposal data that you have (if any):

If you have state-wide annual disposal data...

OI have data on total tons landfilled in my state for all years 1961 through 2(
if you choose this option, skip question 3 and proceed to question 4.

OI have data on total tons landfilled in my state for years 1990 through 20
if you choose this option, annual disposal quantities for years 1961 thri
capita disposal in 1960, 1970, 1980, and your state's per capita disposal in 1990.

If you have no disposal data...

(•) I have no data on annual tons landfilled; use the default for my state.

if you choose this option, emissions calculations are based on state population

3. Enter population data (if state disposal data from 1961-2005 is incomplete)

Population data is necessary in order to backcast disposal data or calculate WIP. This step may safely be skipped (defaults will be used if nec
- Population Data -

Landfills

4. View the preliminary calculations of methane emissions from MSW landfills in Select a State ko to the Calculations

Note that these totals do not yet account for adjustment from methane flaring and LFGTE projects.

5. Adjust CH4 emissions for amount of CH4flared.

If methane flares are in
You can also use default d,

- Flaring Data

OI have data on tor

Choose default or
other population
data

Sheet

View preliminary CH4
emission calculations

WEPA's Landfill Methane Outreach Project (LMOP) database.
[view / Enter / Edit Data

O Use the default (based on information provided by flare vendors J.
O Omit this section; do not account for flaring.

> I

Step (3) Enter Population Data

Unless you have entered disposal data for 1960 through the present, state population data
will be required to calculate emissions. The module automatically uses the default
population data (from U.S. Census). If you want to use population data from another
source, click on the radio button indicating you would like to use your own data. This action
will automatically take you to the population data entry worksheet; you may also navigate
to this worksheet using the gray arrow ("View / Enter Data") to the right of the selection
buttons, as shown in Figure 4.

Landfills

Step (4) View Preliminary ChU Emissions from Landfills

Once you have made your selections and entered data for the previous three steps, you
may view preliminary calculations of ChU emissions from MSW landfills in your state by
clicking on the gray arrow that says "Go to the Calculations Sheet." This worksheet shows
the preliminary results of the FOD model calculations for MSW. These calculations are
considered preliminary because ChU emissions for the amount collected and burned and the
amount oxidized at the surface of the landfill is considered in later steps. The FOD model
estimates the potential ChU emissions that occur during the inventory year, but which are
associated with the waste landfilled over the past thirty years at minimum, using Equation
1.

State Greenhouse Gas Inventory Tool User's Guide for the Municipal Solid Waste Module

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Equation 1. First Order Decay Model Equation

qTx = AxkxRxxL0x ek(T" x>

Where, Qtx = Amount of CH4 generated in year T by the waste Rx,
T = Current year
x = Year of waste input
A = Normalization factor (l-e-k)/k
k = CH4 generation rate (yr1)

Rx = Amount of waste landfilled in year x
L0 = CH4 generation potential

As the equation shows, emissions vary not only by the amount of waste present in the
landfill, but also by the ChU generation rate (k). The ChU generation rate varies according
to several factors pertaining to the climate in which the landfill is located and is
automatically chosen based on the selected state from Step (1). Figure 5 shows the
worksheet where the FOD model is applied. It is not necessary to enter any information on
this worksheet, as its purpose is to clarify how the FOD model is applied to the previously
entered data.

Figure 5. Example of the First Order Decay Model Calculations Worksheet

E State Inventory Tool - Municipal Solid Waste Module

File Edit Module Options Type a question for help ^ _ 1? x

4. Methane Emissions from Landfills in Connecticut Using the First Order Decay Model.

This sheet performs calculations; no data are entered below.

The first order decay (FOD) model estimates the potential CHt emissions that occur during the inventory year, but are associated with the waste landfilled over the past thirty years. These
emissions vary not only by the amount of waste present in the landfill, but also by the CH, generation rate (k). The CHt generation rate varies according to several factors pertaining to the
climate in which the landfill is located. In the Solid Waste module, these factors are simplified into two values, one for arid and one for non-arid states. For arid states (i.e., those states for
which the average annual rainfall is less than 25 inches), a "k" value of 0.02 is used, for non-arid states, a "k" value of 0.04 is used. The methane generation potential (Lq) is equal to 100
m3/metric ton (EPA 1995). The first order decay model is based on the following equation:

Q,„ = A*k*R, *LJ*e-k

Where, QT-> = Amount of CHt generated in year T by the waste R„

T = Current year
x = Year of waste input,

A = Normalization factor, (1 -e+)/k
k = CHt generation rate (yr"')

R, = Amount of waste landfilled in year x
L0 = CHt generation potential

IZI@@

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Step (5) Adjust CH4 Emissions for Amount of ChU Flared

The control worksheet offers three options for adjusting the module to reflect the amount of
CH4 that is flared:

Option 1: If you have state-specific data on short tons of ChU flared, you may enter
these data by clicking on the corresponding radio button, as shown in Figure 6, and
then entering your data on the Flaring worksheet;

Option 2: If you would like to use available default data provided in the module,
select to use the default amount of ChU flared, which is based on U.S. EPA (2021a)
data; or

Option 3: If you do not want to account for flaring of landfill gas in your state, you
may choose to omit this section.

Figure 6. Example of Steps 5 through 8 on the Control Worksheet

E State Inventory Tool - Municipal Solid Waste Module

: File Edit Module Options

EES

Type a question for help " _ S x

Choose type of ChU flaring data

5. Adjust CHU emissions for amount of CHi flared.

If methane flares are in use at landfills in your state, you can enter estimates of the toy

You can also use default data (if available), or omit this section. Default data comj&from EPA's Landfill Methane Outreach Project (LMOP) database.
- Flaring Data

OI have data on tons of methane flared,

O Use the default (based on information provided by flare vendors).
0> Omit this section; do not account for flaring.

View / Enter / Edit D»

6. Adjust CH* emissions for amount of CH4 recovered at landfill-yas-to-energy (LFGTE) projects.

if Landfill Gas to Energy (LFGTE) Projects exist in your state, enter estimates of the landfill gas recovered.

You can also use default data (if available), or omit this section. Default data comes from EPA's Landfill Methane Outreach Project (LMOP
- Recovery Data

OI have data on tons of methane recovered.

Ol do not have data; use the default (LMOP).

Oomit this section; do not account for LFGTE projects.

View / Enter / Edit D

Choose type of
LFGTE data

Go to data entry
sheets

7. Estimate CH4 generated at industrial landfills.

Methane generation from industrial landfills in the U.S. is assumed to be approximately 7% of generation from MSW landfills.
You can adjust this value, if you wish, below, or enter a value of zero to omit industrial landfills from this module.

Methane emissions from industrial landfills are equal to Q

}. Select landfill CH4 oxidation factor

The EPA estimates that 10% of landfill methane that is not flared or recovered is oxidized in the top layer of soil over the landfill
Methane emissions are then reduced by this "oxidation factor." This factor is affected by many factors, including latitude and soil
characteristics. You may use the default or enter your own value below.

Use the
Default?

Enter emissions from
industrial landfills °/o

Enter ChU oxidation
factor

(Check for
Vfe*.

Waste Combustion

Check box for default

9. Fill In the variables that are used to estimate emissions from waste combustion.

Either Type in the value/percentage or Click the Default Box

Gas collection systems have been put in place at many landfills. At some landfills the ChU
collected by these systems is flared. As explained in the Module Overview, the CO2
produced by flaring is not counted as anthropogenic GHG emissions under the accounting
system used in the module, so the quantity of ChU collected and flared may be subtracted
from the total amount of MSW landfill ChU produced, as shown in Equation 2. Likewise, ChU
that is collected and used to create electricity may also be subtracted, as discussed in Step
(6) below.

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Equation 2. Net ChU Emissions from Landfills
Preliminary Net CH4 Emissions =

Total CH4 Generated - CH4 Flared or Recovered for Energy - CH4 Oxidized in Landfill

Step (6) Adjust for Amount of ChU Recovered at Landfill-Gas-to-Energy Plants

As mentioned in Step (5), some landfills collect and burn landfill gas to produce energy.

Such operations are known as landfill gas to energy (LFGTE) plants. The ChU collected and
burned as part of that landfill gas should be subtracted from the total ChU generation, as
shown in Equation 2.

The following three options for adjusting ChU emissions for the amount recovered at LFGTE
plants are provided on the control worksheet:

Option 1: If you have state-specific data on short tons of ChU burned in LFGTE
facilities, you may enter those data by clicking on the corresponding radio button, as
shown in Figure 6, and then entering your data on the LFGTE worksheet;

Option 2: If you would like to use default data provided in the module, select to use
the default amount of ChU recovered at LFGTE plants, which is based on U.S. EPA
(2021a) data; or

Option 3: If you do not account for ChU recovered at LFGTE plants, you may choose
to omit this section and not account for LFGTE operations.

Step (7) Estimate ChU Generated at Industrial Landfills

Up to this point, all information entered in the module refers to ChU generated from MSW
landfills. However, ChU is also generated from waste deposited in non-hazardous industrial
landfills. Although ChU generation from non-hazardous industrial landfills is believed to be
small relative to that from MSW landfills, industrial landfill ChU generation is still a
significant source of ChU emissions. ChU generation from industrial landfills does not include
ChU generation from industrial waste disposed of into MSW landfills, as these emissions
have already been accounted for in the module.

The quantity of waste in industrial landfills and the quantity of ChU that it generates must be
estimated due to a lack of data. Based on estimates of the quantity of waste in place at
industrial landfills and on the estimated organic content of industrial landfills compared to
MSW landfills, U.S. EPA (1993) estimated that ChU generation from industrial landfills in the
United States is approximately 7 percent of ChU generation from MSW landfills in the United
States, prior to adjusting for flaring and recovery or oxidation. If you have outside
information, you may adjust this percent in the yellow box, as shown in Figure 6.

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Step (8) Select Landfill ChU Oxidation Factor

The default assumption in Step (8) of the control worksheet is that 10 percent of the ChU
generated that is not flared or recovered is oxidized in the soil (this holds for industrial
landfills also). To use the default percent, click on the check box. To use your own
oxidation factor, enter it in the yellow box as shown in Figure 6. If the user-specific inputs
do not match the default data in the control worksheet (i.e., the default value is
overwritten), the text will appear red.

Regardless of whether a landfill gas recovery system is in place, uncollected Chk will pass
upward through the landfill cover or surrounding soils, where it may be oxidized (Whalen,
Reeburgh and Sandbeck 1990). The amount of oxidation that occurs is uncertain and
depends on latitude (affecting surface soil temperature), soil characteristics, and other
factors.

Waste Combustion

Step (9) Fill in the Variables Used for Waste Combustion

As described in the Module Overview, combustion of fossil-fuel derived materials in MSW
results in emissions of anthropogenic CO2, N2O, and ChU. To develop an estimate of CO2
emissions, the module calculates combustion of the fossil-derived carbon in MSW for three
waste categories: plastics, synthetic fibers (e.g. textiles), and synthetic rubber (U.S. EPA
2020). The defaults in the Municipal Solid Waste module use information on the typical
composition of discards in the U.S. solid waste stream to estimate the mass of each of these
waste types that is combusted and estimates the proportion of each material that comprises
fossil carbon. The module defaults also assume that 98 percent of the fossil carbon is
converted to CO2 in the combustion process (with the balance remaining in the ash).

Some of the data inputs required to complete estimates of GHG emissions from waste
combustion are entered on the control worksheet as shown in Figure 7, and the remaining
data inputs are entered on individual calculation worksheets for each type of material, as
well as for N2O and ChU emissions.

Fraction of Waste Oxidized

Enter the fraction of carbon that is oxidized for each material type in the yellow boxes on
the control worksheet as shown in Figure 7. To use the default percent oxidized (98
percent); use the check boxes to the right of the yellow cells. If the user-specific inputs do
not match the default data in the control worksheet (i.e., the default value is overwritten),
the text will appear red.

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Module 9 - Municipal Solid Waste Module

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Figure 7. Example of Steps 9 through 11 on the Control Worksheet

I D State Inventory Tool - Municipal Solid Waste Module

~BE

|:Sj Rle Edit Module Options

| Type a question for help » _ B X |

Waste Combustion

9. Fill In the variables that are used to estimate emissions from waste combustion.

Either Type in the value/percentage or Click the Default Box

Fraction Oxidized
Plastics

Synthetic Rubber in MSW
Synthetic Fibers

Default
Fraction
Oxidized

Fraction
Oxidized
Used

Enter percent oxidation in
combusted wastes

Check boxes for default

Enter waste combustion data for your state or use the default values

- Waste Combustion Data

Ol have data on tons of municipal solid waste combusted, 1990-2008.

Ouse the default data.

10. -13. Proceed to the following combustion worksheets to calculate

10. C02from Plastics Combustion

11. CCMiom Combustion of Synthetic Rubber in MSW

12. C02from Combustion of Synthetic Fibers

13. N;0 fi om MSW Combustion

14. CHjfrom MSW Combustion

[View / Enter / Edit frata

e^^^ions:

Choose type of
combustion data

Go to the Plastics Combustion Sheet

6o to the Synthetic Rubber Combustion Sheet

Go to the Synthetic Fiber Combustion Sheet

Go to the NjO from MSW Combustion Sheet

Go to the CH4 from MSW Combustion Sheet

Go to combustion
worksheets

15. After completing steps 1 through 14. click View Results to proceed to the emissions summary worksheet for California.

| View Summary Sheet

16. Export the results for use in the Synthesis Tool.

Export Data

Go to summary

Export data

Default or User-Entered Data

The module allows you to enter your own data on short tons of waste combusted in-state
for the years 1990 through the present, or to use the default data, which is based on
BioCycle (1991-2008). Choose the appropriate radio button; if you choose to enter your
own data, this action will take you to the data entry worksheet. You may also navigate to
this sheet using the gray "View / Enter / Edit Data" arrow to the right of the buttons. After
completing this section of the control worksheet, go on to the combustion sector calculation
worksheets.

Step (10) Complete the CO2 from Plastics Combustion Calculation Worksheet

There are separate worksheets for each of the three types of fossil-derived MSW (plastics,
synthetic rubber, and synthetic fiber) and each of the worksheets is similar in layout. An
example of the plastics combustion worksheet is shown in Figure 8. Emissions are
calculated using the following equation:

Equation 3. CO2 Emissions from Combustion

CO2 Emissions (MTCO2E) =

Material as Proportion of all Discards (%) x Total MSW Combusted (short tons) x Carbon
Content (%) x Fraction Oxidized (%) x 44/12 (CO2 to C ratio) x 0.9072 (short tons to

metric tons conversion)

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On the plastics combustion worksheet, enter the proportion of each type of plastic (PET,
HDPE, PVC, LDPE/LLDPE, PP, PS, and other) as a percent of total discards in the blue cells.
The default data are from U.S. EPA (2020), and may be selected by clicking the check box
for each year, as shown in Figure 8, or by clicking the box "Select All Defaults." Total tons
of waste combusted are drawn from the data you entered in Step (9); default carbon
contents are provided for each type of plastic. Once you have entered data for each year,
you may proceed to the synthetic rubber combustion worksheet by clicking on the gray
arrow at the top of the page.

Figure 8. Example of Plastics Combustion Calculation Worksheet

I ~ State Inventory Tool - Municipal Solid Waste Module

BBS

| i Sj File Edit Module Options

Type a question for help £ _ 1? x |

10. CO2 from Plostics Combustion in Connecticut

In the calculation of C02 emissions from plast
combusted. Default values or user-supplied c
This value is then multiplied by the proportion
the waste, and the faction oxidized to deternfll It! LU; bflliyyilll iy.
MTCE and MTCO^. The methodology and factors used for the;
Solid Waste Chapter of the User's Guide

Combustion data from
data entry worksheet

COz from Plastics Combustioi

tent of

|yyy vaiuuy aiu lmuii uuiivymJdto

alculations are discussed in detail in

Return to the
Control Sheet

So to the Synthetic
Rubber Combustion She

Select All Defaults

CO2 from Ploswics Combustion

Plastics

PET

State MSV
Combusted
(short tons)

CO2 from Plostics Combustion

Proportion of Discards?

1991

io.8x

^ X

t.885.000

79%

0.8 % ^

1,885,000

63 X

Enter material as
proportion of all discards

86%

38%

86 %

86%

1.3%

1,885,000

92%

1.2 %

1,885,000

66%

Go to synthetic
rubber worksheet

Emissions
(MTCO,E)

Check box for default

proportions

72.000

62.198

38.986

Fraction oxidized from

control worksheet

524.355

30.784

99.991

21.331

159.986

88.246

76.233

47.783

1992

W Default Proport ion of Discards?

Step (11) Complete the CO2 from Synthetic Rubber Combustion Calculation
Worksheet

The synthetic rubber combustion worksheet is identical to the plastic combustion worksheet,
except that it calculates emissions for durable goods, non-durable goods (clothing and
footwear, and other non-durables), and packaging and containers made of synthetic rubber.
Enter the proportion of each type of rubber in the green cells as a percent of total discards,
or select the default data (U.S. EPA 2020). Once you have entered data for each year, you
may proceed to the synthetic fiber combustion worksheet by clicking on the gray arrow at
the top of the page.

Step (12) Complete the CO2 from Synthetic Fiber Combustion Calculation
Worksheet

Again, this worksheet is identical to the worksheets for plastic and synthetic rubber
combustion. Enter synthetic fiber as a proportion of all discards, in the orange cells, or

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choose the default proportions. The carbon content provided is a weighted average of the
carbon contents of the major synthetic fibers used in the United States. Once you have
entered data for each year, you may proceed to the N2O from MSW combustion worksheet
by clicking on the gray arrow at the top of the page.

Step (13) Review Estimates on the N2O from MSW Combustion Calculation
Worksheet

This worksheet does not require any data inputs; it presents an example of how the
emissions are calculated based on the following equation (the emission factor is from U.S.
EPA 2021b):

Equation 4. N2O Emissions from Combustion

N2O Emissions (MTCO2E) =

MSW Combusted (short tons) x 0.00005 (emission factor in tons N20/ton MSW) x 298
(N2O GWP) x 0.9072 (short tons to metric tons conversion)

Step (14) Review Estimates on the ChU from MSW Combustion Calculation
Worksheet

This worksheet does not require any data inputs; it presents an example of how the
emissions are calculated based on the following equation (the emission factor is from U.S.
EPA 2021b):

Equation 5. CH4 Emissions from Combustion

CH4 Emissions (MTCO2E) =

MSW Combusted (short tons) x 0.00002 (emission factor in tons N20/ton MSW) x 25
(CH4 GWP) x 0.9072 (short tons to metric tons conversion)

Step (15) Review Summary Information

The steps above provide estimates of total emissions and reductions from municipal solid
waste management. The information from the control worksheet and data entry worksheets
is collected on the summary worksheet, which displays results in million metric tons of
carbon dioxide equivalent (MMTCO2E). Figure 9 shows the summary worksheet that sums
the emissions from all sectors in the Municipal Solid Waste module. In addition, the results
are displayed in graphical format at the bottom of the summary worksheets.

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Module 9 - Municipal Solid Waste Module

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Figure 9. Example of the Emissions Summary Worksheet in the Municipal Solid

Waste Module

E State Inventory Tool - Municipal Solid Waste Module

;aj File Edit Module Options

BBS

Type a question for help » . S X

1^. Connecticut Emissions Suntitiory

This Worksheet Provides a Summary of Emissions from Londfills ond Waste Combustion Once All Control Steps Hove Been Completed.

Return to the
Control Sheet

Review discussion of uncertair
associated with these results

ItsJ^>

Emissions were not calculated for the following sources: Waste Combustion- Synthetic Rubber.

Totol Emissions from Landfills and Waste Combustion (MMTCO2E)

1990

1991

1992

1993

1994

1995

1996

1997

19'

CH4

0.855

0.879

0.873

0.793

0.784

0.770

0.762

0.753

0.63

co2

0.545

0.669

0.579

0.496

0.689

0.705

0.737

0.758

0.85

NsO

0.021

0.023

0.020

0.016

0.023

0.022

0.02

Total

1 420

1 572

1 473

1 305

1 495

1 497

1 520

1 533

1 51

CH4 Emissions from Landfills (MTCOgE)

1990

1991

1992

1993

1994

1995

1996

1997

19'

Potential CH4

949 517

97*, 917

970,140

969,933

959,418

943,906

934,997

925,605

916,57

MSW Generation

887,399

913,007

906,672

906,479

896,653

882,156

873,829

865,051

856,60

Industrial Generation

62,118

63,910

63,467

63,454

62,766

61,751

61,168

60,554

59,96

CH4 Avoided

(88,858)

(211,56

Flare

Landfill Gas-to-Energy

(88,858)

(211,56

Oxidation at MSW Landfills

88 740

91,301

90, <<7

81,7*2

80,779

79,330

78,497

77,619

64,50

Oxidation at Industrial Landfills

6.212

<,391

6,347

6,345

6,277

6,175

6,117

6,055

5,99

Total CH4 Emissions

854,565

879,22 6

873,126

792,967

783,504

769,544

761,525

753,072

634,50

Step (16) Export Data

The final step is to export the summary data. Exporting data allows the estimates from
each module to be combined later by the Synthesis Module to produce a comprehensive
GHG inventory for the state.

To access the "Export Data" button,
return to the control worksheet and
scroll down to the bottom (15). Click
on the "Export Data" button and a
message box will open that reminds
the user to make sure all sections of
the module have been completed. If
you make any changes to the
Municipal Solid Waste module later,
you will then need to re-export the
results.

Clicking "OK" prompts you to save the file. The file is already named, so you only need to
choose a convenient place to save the file. After the file is saved, a message box will
appear indicating that the data was successfully exported.

While completing the modules, you are encouraged to save each completed module; doing
so will enable you to easily make changes without re-running the entire module.

Following data export, the module may be reset and run for another state. Alternatively,
you may run the remaining modules of the State Inventory Tool to obtain a comprehensive
profile of emissions for your state.

Note: the resulting export file should not be
modified. The export file contains a summary
worksheet that allows users to view the results, as well as
a separate data worksheet with an unformatted version of
the results. The second worksheet, the data worksheet,
contains the information that is exported to the Synthesis
Tool. Users may not modify that worksheet.
Adding/removing rows, moving data, or making other
modifications jeopardize the ability of the Synthesis
Module to accurately analyze the data.

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1.4 Uncertainty

In the upper right-hand corner of the summary worksheet is a button: "Review discussion of
uncertainty associated with these results." By clicking on this button, you are taken to a
worksheet that discusses the uncertainty surrounding the activity data and emission factors,
and how the uncertainty estimates for this source category affect the uncertainty of the
emission estimates for your state.

1.5 References

BioCycle. 1991-2008. "The State of Garbage in America: Annual Nationwide Survey."
BioCycle.

U.S. Census Bureau. 2020. 2000-2020 Population. U.S. Census Bureau, Washington, DC.
Available online at: http://www.census.aov.

U.S. EPA. 2020. Advancing Sustainable Materials Management Facts and Figures. Available
online at: https://www.epa.aov/facts-and-fiaures-about-materials-waste-and-
recvclina/advancina-sustainable-materials-manaaement.

U.S. EPA. 2021a. Landfill Gas-to-Energy Project Database 2021, Landfill Methane and
Outreach Program. Obtained from EPA on October 18, 2021. State-level data are
available online at: https://www.epa.aov/lmop/proiect-and-landfill-data-state.

U.S. EPA. 2021b. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 - 2019.
Office of Atmospheric Programs, U.S. Environmental Protection Agency. EPA 430-R-21-
005. Available online at: https://www.epa.aov/ahaemissions/inventorv-us-areenhouse-
aas-emissions-and-sinks

U.S. EPA. 1993. Anthropogenic Methane Emissions in the United States: Report to
Congress. Global Change Division, Office of Air and Radiation, U.S. Environmental
Protection Agency, EPA/430-R-93-003. Washington, DC.

Whalen, S.C., W.S. Reeburgh, and K.A. Sandbeck. 1990. "Rapid Methane Oxidation in a
Landfill Cover So\\," Applied and Environmental Microbiology. November 1990.

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