EMIT User Guide

Overview

The Emissions and Modeling Impacts Tool (EMIT) is a standalone component of the broader Air Resources Toolkit. The toolkit was developed by the Bureau of Land Management (BLM) to aid individuals needing to prepare air resources related National Environmental Policy Act (NEPA) analysis to support various BLM managed activities. EMIT is a user-friendly single page web application designed to generate project specific emissions inventories and impacts analyses using a variety of regulatory tools and methods. EMIT is based on many years and iterations of emissions inventory tool development and NEPA analyses that have been widely used and accepted as state of the practice appropriate.

This User’s Guide was designed to guide users through the process of analyzing emission-generating projects. This guide also provides information on the equations used by EMIT in calculating emissions and shows how the inputs provided via EMIT are used in these equations.

EMIT provides emissions estimates for direct and indirect pollutants for each of the following categories:

• Criteria Pollutants
  • Particulate Matter with an Aerodynamic Diameter of 10 microns or less (PM₁₀)
  
  
  • Particulate Matter with an Aerodynamic Diameter of 2.5 microns or less (PM_2.5)
  
  
  • Nitrogen Oxides (NO_X)
  
  
  • Carbon Monoxide (CO)
  
  
  • Sulfur Dioxide (SO₂)


• Volatile Organic Compounds (VOCs)
  • VOCs are numerous, varied, and ubiquitous through the natural and man-made environments
  
  
  • Carbon based chemicals with low boiling point that readily evaporate or sublimate at room temperatures
  
  
  • Can participate in smog forming reactions (ozone precursor)
    
  • EMIT presents VOCs as an aggregated total (i.e., no speciation, or reactivity indexing is provided)
  
  


• Hazardous Air Pollutants (HAPs)
  • HAPs are known to cause cancer and other serious health impacts
  
  
  • 187 specific chemicals and several metal compounds (e.g., cadmium, mercury, chromium, and lead)
  
  
  • EMIT presents HAPs as an aggregated total


• Greenhouse Gases (GHGs)
  • Carbon Dioxide (CO₂)
  
  
  • Methane (CH₄)
  
  
  • Nitrous Oxide (N₂O)
  
  
  • EMIT uses Global Warming Potentials (GWPs) for the listed GHGs as follows: 1, 36, 298

EMIT Navigation

User navigation throughout the EMIT model is described in this section.

Panels

The EMIT screen is consistently divided into three panels throughout all applications of the model: the route navigation panel, the screen navigation panel, and the main screen. The three panels of the screen are identified in Figure 1, which is a screenshot of the opening EMIT display.

Figure 1. Screenshot Showing EMIT Panels

The panel on the left, the route navigation panel, allows the user to select one of six model routes. The six routes that the user can select in this panel are:

• Modules—Use to create a new project or select an existing project and select the EMIT module.


• Module Forms—Use to enter the data specific to the project.


• Emissions—Use to tabulate and display the resulting project emissions.


• Modeling—Use to create input files for dispersion modeling.


• Reports—Use to summarize the project data and create conformity reports.


• Settings—[TBD]

Typically, a user would follow each of these model routes sequentially in the process of evaluating a project and determining whether it meets the General Conformity requirements established under the NEPA.

The panel to the right of the route navigation panel is the screen navigation panel. The user selection on this panel determines the information included on the main screen. The user can collapse the route navigation panel by toggling the three horizontal bars at the top left of the screen navigation panel.

The main screen is where the user enters and evaluates the project data.

Project Actions

When creating a new project, via the Modules route in EMIT, there are four actions that can be taken with each project listed. The project action controls are shown in Figure 2, which represents an EMIT screenshot of the main screen, when the Modules route is selected in the route navigation panel.

Figure 2. Location of Project Action Controls

• Load:  A project must be loaded before any project data can be entered in the data forms. Only one project can be loaded at a time and is considered to be the active project. In order to load or delete another project, there must be no active project. If there is an active project, close the active project using the close icon in the Right Drawer Control from the Module Forms route and then load or delete the desired project.


• Copy:  This copies the listed project and all data associated with the project to a new project. The user will need to enter new project information for the copied project, but all associated data from the original project will be carried over.


• Delete:  This deletes the selected project. As noted above, all projects must be closed before any project can be deleted.


• Admin:  Selecting this icon will bring up a panel on the right of the screen with administrative information and options

Once a project has been loaded, the user can then move to fill in data associated with the project through the Module Forms route in EMIT.

Right Drawer and Tab Controls

When the Module Forms route is selected, a set of additional actions are available to the user through the right drawer controls, which appear on the right center side of the main screen as shown in Figure 2.

Figure 3. Location of EMIT Right Drawer Controls and Tab Controls

The actions associated with clicking on each of these control icons are described below.

• more_vert    Information: Clicking on this icon opens a panel that will appear on the right side of the screen. This panel provides information relevant to the data in the currently selected module and module form. This information is revealed by clicking on any of the arrows to the right of the blue headers. The items likely to be most useful the user are the Field Data and Model Data. Clicking on the Field Data selection provides information and/or guidance about the active field (the field in the module form where cursor is currently located). As the user moves the cursor from field to field in the module form, the Field Data in the information pane automatically updates to the currently active field. Selecting Model Data in this informational panel reveals the data fields currently stored in the EMIT database relevant to the currently selected module form.
• save    Save Project: Clicking on this icon saves all information entered for the currently loaded project. The project must be saved before being closed or all unsaved information will be lost. After this icon is clicked, the message “SUCCESS: Project Data Saved!” will appear at the top of the screen if the save was successful.
  info Be sure to save your project often. If a project is closed without first saving it, all data entered since the previous save will be lost!
• move_to_inbox    Defaults: (TBD)
• functions    Calculations: Clicking on this icon will display a screen with summary information on intermediate parameters needed in the emissions calculations. These parameters are calculated in EMIT based on information entered by the user on the current and other associated module forms. Clicking on any of the displayed calculated parameters shows the EMIT calculation dependencies for that parameter, including the module form where the necessary data is entered. To return to the same module form, click the X icon in the upper right corner (not the browser back button).
• eject    Close Project: Clicking this icon will close the project. A project must be closed before another can be opened. Be sure to save the project before closing it.

Data for some of the module forms are rendered in EMIT as 'array' types, meaning that users can enter multiple sets of data on these module forms to fully characterize or describe describe the activity or process. For example, the On-Road Vehicles Module Form allows only one vehicle class to be selected. If a project includes activity from both heavy-duty diesel trucks and light duty gasoline vehicles, then the user would define the activity for each of these vehicle types on a separate tab. Note that not all module forms support multiple tabs. For the module forms that do support multiple tabs, the upper right corner of the main screen includes tab controls, as shown in Figure 2. Labels for each tab are listed on the top left of the data entry screen, with the active tab in blue font.

The actions associated with clicking on each of these tab control icons is described below.

• add    Add: Clicking on the Add control provides a new blank module form for data entry by the user. A new tab label for the new entry will appear at the right end of the existing tab labels, with no data entered. Click on that tab to enter data.
• file_copy    Copy: This control copies the active tab data to a new tab that is rendered at the right end of the existing tabs. Data from the copied tab will be entered automatically and can be revised by selecting the new tab.
• delete_forever    Delete: The Delete control removes the active tab and data from the set of existing tabs. Note that this action cannot be undone.
• fullscreen    Full Screen: Clicking on this icon will switch the EMIT model to the full screen. This icon appears in the upper right corner for all modules and routes.

Projects

Creating a Project

The first step in using EMIT is to create a new project. Projects are created and loaded from the Modules route of EMIT. When EMIT is first opened, the Modules route is shown. To create a new project, the user must select New Project Form from the top of the screen navigation panel as well as the appropriate EMIT module at the bottom of the screen navigation panel from the Module Selection dropdown menu, which includes the following eight modules:

• Fluid Minerals: Oil, Gas, and CO2 Development
• Solid Minerals: Coal, Locatable, and Saleable Mineral Mining
• Forestry: Timber and Wood Products
• Grazing: Cattle, Sheep, Bison, and Horse Allotments
• Travel Management: Route and OHV Management
• Right of Ways: Access, Power, and Pipeline Emissions
• Vegetation Management: Prescribed Fire, Mechanical, and Chemical Treatments
• Renewable Energy: Wind and Solar Power Development

Once a project has been created in the EMIT Tool, it must be loaded before project parameters can be entered and emissions calculated for the project. From the Modules route, select My Projects in the navigation screen. All existing projects of the selected module type for the user will be listed in the main screen. Available project actions are described in the Project Actions section. Data for a loaded project can be entered by selecting the Module Forms route in EMIT.

In the main screen, the user then enters information pertinent to the project to be modeled. All fields other than Description must be populated for a new project to be created. Filling in the Description field is optional, but strongly recommended, particularly if the project information and emissions will be submitted to BLM. The fields included in this menu are shown below.

Once all fields are populated accordingly, the user must click the CREATE button in the bottom right corner of the tool. If the project has been successfully created, a success message will briefly appear at the top of the screen (SUCCESS: Project Created). If no other project is currently loaded, the user will automatically be taken to the Module Forms route tab.

Quick Start: Developing an Example Project

The steps needed to model a hypothetical simple project in EMIT that involves only travel by on-road vehicles are shown below.

Module Forms

Navigating the Module Forms Screens

The Module Forms route provides the data screens where the user enters the specific data that define their project. The Module Forms specific to the selected Module are listed in the screen navigation panel. Clicking on the name of any of these Module Forms takes the user to that portion of the input. Each Module Form contains the entries for the user to input the data needed to identify and calculate emissions for a related group of activities or equipment.

Users can explore the Module Forms associated with each loaded module by clicking on the specific list item in the Module Forms route of EMIT. These forms should be completed in order from top to bottom. The activities in the various forms build upon each other and users may experience unexpected results if certain form data are missing from a previous form in the list (for example, emissions calculations may not return a valid result).

After completing data entry on any of the module forms, the user can click on the calculations icon in the Right Drawer Controls, as shown in Figure 3, to verify that all of the necessary data needed to make emissions calculations for that particular sub-activity / equipment type have been entered. The parameters and values listed when the calculations icon is clicked reflect either user-entered data or a calculated value that EMIT has generated based on the entered data. These intermediate parameters are generally need for one or more emissions calculations in EMIT. EMIT provides the user with parameter dependency information for all the displayed calculated values and informs a user of which data inputs need to have entered in order for that variable to be properly calculated by EMIT. When the user clicks on one of the calculated parameters shown, EMIT will display a list of required inputs and indicates which Module Forms those inputs are entered on. A red X in front of the input indicates that the user has not entered valid data for that input, while a green check mark indicates that the input has a valid entry.

Fluid Mineral Module Forms

Use this module to estimate emissions from oil, gas, and carbon dioxide (CO2) mineral development. This module estimates emissions from both construction and production related activities and provides delineation for fee/fed wells (where only a portion of the production is from federal mineral estate). Of all the emissions modules in EMIT, this one has by far the most required user inputs simply due to the complex nature of the industry.

Project information and data needed to calculate emissions for fluid minerals projects should be entered in the following EMIT Module Forms:

• LOCATION DATA: Use the Location Data form to capture localized attributes specific to your project area, including climate, surface characteristics, and access routes.


• DEVELOPMENT DETAILS: Use the Development Details form to capture specific development attributes of you project.


• INFRASTRUCTURE: Use the Infrastructure form to record basic infrastructure data at project development site(s). Data should include information on well pads, access roads, and pipelines. Create as many entries as required for your project.


• GAS PROFILES: Use the Gas Profiles form to record gas profile / speciation data, create as many as required for your project.


• ON-ROAD VEHICLES: Use the On-Road Vehicles form to capture highway traffic, including worker trips, deliveries of materials and equipment, production hauling, and general travel. Emissions estimates for onroad vehicles include combustion exhaust and fugitive dust from roadway surfaces.


• NON-ROAD EQUIPMENT: Use the Non-Road Equipment form to capture engine data used in a wide range of applications, including heavy equipment, recreational vehicles, locomotives, aircraft, and small equipment and tools.


• DRILL RIGS: Use the Drill Rigs form to capture specific drill rig data for your project. In general, drill rigs are scaled on a per well basis. However, the form does provide a well service count parameter to allow users to specify a varying degree of use.


• COMPLETIONS: Use the Completions form to capture project specific data regarding well completions.


• TANKS: Use the Tanks form to capture specific tank and tank battery data. Enter as many tank design parameters as necessary to accurately reflect project attributes.


• FIELD GAS PROCESSING: Use the Field Gas Processing form to capture specific data for field gas processing units, including dehydrators and sour gas amine treaters. Flow controllers and process heaters should be specified elsewhere.


• PROCESS HEATERS: Use the Process Heaters form to capture specific heater data.


• COMPONENTS: Use the Components form to capture specific component data.


• PNEUMATIC DEVICES: Use the Pneumatic Devices form to capture specific pneumatics data. Alternatively, if all pneumatic devices are zero bleed or are driven by instrument air, you may elect to remove this form from the data collection process.


• STATIONARY ENGINES: Use the Stationary Engines form to capture specific engine data.


• PRODUCTION OPERATIONS: Use the Production Operations form to capture specific operational events that could produce emissions from venting that are not captured elsewhere, specifically for well blowdowns and workovers.

This module uses the following emission calculation packages:

• Fugitive Dust – Unpaved Road Commuting Operations
• Fugitive Dust – Heavy Construction Operations
• On-Road Vehicle Exhaust and Evaporative Emissions
• Non-Road Mobile Equipment – Exhaust and Evaporative Emissions
• Drill Rig Emissions
• Stationary Engines
• External Gas Combustion – Process Heaters
• Well Completions
• Venting and Flaring from Well Production Operations
• Storage Tank and Truck Loadout Fugitive Emissions
• Field Gas Processing
• Equipment Leaks
• Pneumatic Devices

Solid Minerals

Forestry

Grazing

Travel Management

Right of Ways

Vegetation Management

Renewable Energy

Emissions

Once project data has been entered on the module forms for a project, the resulting emissions as calculated by EMIT are presented in the main screen. When the Emissions module is selected, the screen navigation panel provides several view selectors for reviewing project emissions associated with the loaded project. The user can select between three configurations for viewing emissions results: Table, Pie Chart, or Line Chart. Additionally, on the screen navigation panel, the user can choose to view emissions from either all criteria and hazardous pollutants (PM10, PM2,5, VOC, NOx, CO, SO2, and HAPs) or from greenhouse gases (CO2, CH4, N2O, and CO2e), by clicking the button in front of one of these options. Finally, the screen navigation panel provides a checkbox for selecting to display only Federal emissions (i.e., just the portion of emissions associated with Federal minerals, as identified on the Development Details module form in the Percent Federal Mineral data entry).

Emissions can be displayed in one of three ways:

• Table: Selecting Table in the Emissions pane brings up a comprehensive and detailed tabular display of emissions as calculated by EMIT using the data entered for the loaded project. Emissions are itemized by activity, including all emission-generating activity for which emissions could be calculated based on the data included on the module forms. The Description column of the emissions table identifies the activity for which emissions have been calculated. The user may notice that the same activity may be listed several times in the Description column. This happens because the emissions are expressed in different metrics. It is important to consider the corresponding entry in the Units column of the emissions table to understand what each row of emissions data represents. For example, the same activity may have emissions expressed as tons/project, tons/yr, tons/well, etc. The Units column is followed by the columns of emissions for each pollutant, based on the selection made in the Emissions pane (either Criteria & Hazardous Pollutants or Greenhouse Gases).


• It is also important to note that module forms with data entered on multiple tabs with the same name will appear with identical activity names in the Description column and units in the Units columns, but with different emissions, assuming different data were entered on the different tabs. As an example, on the On-Road Vehicles module form, the user could add multiple tabs for a given task (e.g., daily site visits), with each tab representing emissions from a different vehicle class. In this case, the emissions table would list the activity “On-Road Fugitive Dust – Public Dirt Roads – Daily Site Visits” twice for both sets of units (tons/entry and tons/project). In this case, the entries are shown in the same order as the tabs on the module form that characterizes the activity (i.e., starting with the activity on the leftmost tab and then continuing with each tab moving to the right).


• Three actions are available within the table view:
  
  
  • Sorting Data: All of the pollutant fields and the Units field are sortable by clicking on the column name.
  
  
  • Filtering Data: The upper right corner of the Table View screen includes a search bar for filtering emission results. This enables the user to focus on viewing emissions associated with a specific activity or set of units. For example, by entering “tons/project” in the search bar, the emission results would show just the total project emissions for each activity
  
  
  • Exporting Data: The entire emissions data table can be exported to a CSV file by clicking on the export icon in the top right corner of the table view, and then selecting whether to open or save the file as named. (The export file name is based on the project name.) Note that any filtering or sorting currently in effect in the table view does not impact the exported data. All data rows associated with the selected project are exported.


• Pie Chart: Selecting Pie Chart in the Emissions pane will result in the display of a pie chart that shows the compositions of the total project emissions by pollutant for the selected set of pollutants (either Criteria & Hazardous Pollutants or Greenhouse Gases). Clicking on any of the pie wedges will bring up a pie chart showing the contribution of each activity to the total emissions of that pollutant. In either the pie chart of emissions by pollutant or the emissions of activities within a pollutant, hovering over the pie wedge will show the emissions from that wedge.


• Line Chart: [TBD, under construction]

Modeling

By selecting the Modeling icon from the route navigation panel, the user is provided with tools for developing input files for dispersion modeling. Four selections can be made from the Modeling screen navigation panel.

Project Map:

• Selecting Project Map from the Modeling screen navigation panel brings up a map of the United States. The user can then zoom in to the project location and then click on the appropriate point of the map to indicate the site of an emissions source or an emissions receptor. EMIT will then add a pin to the map at this point.


• Clicking on the pin then opens a Map Model Tools panel on the right side of the screen. Here, the user can select either Source or Receptor from the Marker Type drop-down menu.


• If Source is selected, the user can then define the source parameters: source ID and source type. Finally, the user can enter the emission rate of the source in terms of grams per second. Alternatively, by clicking on the IMPORT EMISSIONS button at the bottom of this panel, EMIT will bring up another menu detailing the sources from the currently loaded project. The user can then check one or more of these sources and then click IMPORT at the bottom right of this menu. EMIT will then automatically pull in the emission rates calculated for the selected equipment.


• If Receptor is selected from the Marker Type drop-down menu, the user is then able to enter an ID, the elevation, and the height above ground of the receptor.


• This process can be repeated for multiple receptors and sources.

Ambient Backgrounds:

• Selecting Ambient Backgrounds from the Modeling screen navigation panel brings up a screen for entering background ambient pollutant concentrations of PM10, PM2.5, CO, NO2, and SO2. Note that the units expected for each pollutant depend upon the averaging period.

Model Settings:

• The main screen provides the user with the ability to select and set the dispersion model options when Model Settings is selected on the screen navigation panel. This includes data on the basic run data, model settings, meteorology and surface settions, source options, and receptor and terrain processing. Note that sources and receptors that are defined on the Project Map screen are available for selection in the Source Options and the Receptor & Terrain Processing menus, respectively.

Input Preview:

• Selecting Input Preview from the Modeling screen navigation panel displays the code, generated by EMIT, to be used as input to a dispersion model, based on the information provided by the user.

Reports

The Reports screen navigation panel provides the user with access to two different types of automated reports for summarizing the project data. The first includes module fields and project data reports, which provide the user with summary information about the project data needed for EMIT or entered by the user in EMIT. The second includes general conformity reports which evaluate the resulting project emissions in comparison to general conformity requirements. Both of these report types are discussed below.

Module Fields & Project Data:

• The reports that can be generated via the Module Fields & Project Data selection from the screen navigation panel are designed to provide users with a detailed look at all the module forms and fields associated with the selected EMIT module. This report can then be distributed among the various parties associated with the project to get an understanding of the data needs for EMIT and to begin gathering the required data on the various activities associated with the project. In order to generate this report, the user must select the desired module on the drop-down menu in the Reports screen navigation panel. Once a module is selected, a RUN REPORT button will appear below the selected module. Clicking on this button will generate the selected report. There is a PRINT button at the top right of the screen. By clicking this button, a print dialog box will open, and the user can make the desired selections to print the report.
• 
  By checking the Include Project Data box at the bottom of the Reports screen navigation panel, the generated report provides a listing of all the data fields included in the module forms with the user-entered values for the currently loaded project and selected module. This report is a particularly useful tool for enabling all involved project members to review the data entered in EMIT without the need for everyone to use the tool itself. Once the user clicks the RUN REPORT button, report header information will appear including the module and project name. This project name is the currently active project in EMIT. If this report is desired for a different project, the user should close the existing project, return to the Modules screen navigation panel, and load the desired project from the list of projects. The preview of the Project Data report that is generated by clicking the RUN REPORT button will be populated with all the module form fields and the entered values. For module forms with multiple tabs, the values for each tab are displayed in sequential columns with a generic header (e.g., Value 0, Value 1, Value 2, etc.). Clicking on the PRINT button at the top right of the screen opens a print dialog box where the user can make the desired selections to print the report.

• The general conformity reports screen includes two dropdown menus—one to select the NAAQS designation status of the project area and one to select the relevant pollutant that the designation applies to. The options for designation include: Maintenance; Maintenance – Ozone Transport Region; NAA Moderate or Marginal; NAA Moderate or Marginal – Ozone Transport Region; NAA Serious; NAA Severe; and NAA Extreme. The available selections for pollutant are: PM10, PM2.5, CO, NO2, SO2, and Ozone. Once a selection has been made for both the designation and pollutant, click on the ADD POLLUTANT button. Multiple combinations can be selected in this same manner. Once all applicable combinations of NAAQS designation and pollutant have been made, the user must click the RUN REPORT button at the top right of the main screen and the report will be generated on the screen. If the checkbox for Show Extended Report (located at the bottom of the Reports screen navigation panel) is not checked, the report summarizes the general conformity requirements, indicates whether the general conformity requirements do or do not apply for the selected project, and finally displays for each pollutant and designation combination the de minimis emissions total of the pollutant needed for general conformity to apply, the project’s total emissions of the pollutant, and whether emissions from the pollutant pass or fail the general conformity screening check. If the Extended Report option has been selected, the report also lists the total project emissions of each of the selected pollutants, summarized by activity. As with the other reports, there is a PRINT button at the top right of the screen to allow the user to print the report.

Emission Calculations

This section provides details on the emission calculations within EMIT. Variables that are entered by the user are noted, along with the corresponding module and data field where the variable should be entered.

Scalars

In order to estimate emissions for the entire duration and scope of the project, a number of modules include an entry for the user to indicate whether provided data should be scaled. This entry appears as follows:

The following module forms include this scaling selector:

• ON-ROAD VEHICLES
• NON-ROAD EQUIPMENT
• FIELD GAS PROCESSING
• PROCESS HEATERS
• COMPONENTS
• PNEUMATIC DEVICES
• STATIONARY ENGINES

The user must select one of the scaling selector options, or emissions that are calculated with this scalar will not be calculated. The resulting scalar is determined as follows, based on the user’s selection:

• As-Is: The scalar used is 1, so emissions are unaffected. This should be considered the default if the user has no additional information for applying a scalar to the entries in the corresponding module form.
  
• Explicit Multiplier: When “Explicit Multiplier” is selected, EMIT adds a Multiplier entry in the corresponding module form. The user-supplied input for this Multiplier will be used as the scalar. If this entry is left blank, EMIT will not calculate emissions associated with the corresponding module’s entries on that input tab.
  
• Per Well Pad:The data needed for EMIT to calculate the scalar when Per Well Pad is the selected option is entered on the INTRASTRUCTURE module form. The INTRASTRUCTURE module form asks “Scale this entry to represent multiple well pads, access roads and pipelines?” If the box in front of this question is checked, a Multiplier entry appears. The user input for this Multiplier entry is then used as the scalar if “Per Well Pad” is the chosen as the scaling selector option. If the box is not checked, then the scalar is set to 1.
  
• Per Well: The data needed for EMIT to calculate the scalar when “Per Well” is the selected option is entered on the INTRASTRUCTURE module form. The entry for Number of Wells per Pad is multiplied by the number of pads to obtain the “Per Well” scalar, both of which are obtained from the INTRASTRUCTURE module form. The number of pads is the multiplier entered by the user in the Multiplier entry that appears if the box in front of “Scale this entry to represent multiple well pads, access roads and pipelines?” is checked. If this box is not checked, the Multiplier defaults to 1.
  

Fugitive Dust - Unpaved Road Commuting Operations

This section describes how EMIT estimates fugitive dust emissions from traffic on unpaved public and industrial roads. The calculations are for particulate matter emissions only and do not include the associated tailpipe emissions from vehicle fuel combustion which are calculated separately as documented in the On-Road Vehicle Exhaust and Evaporative Emissions section. The emission calculations are based on the methodologies outlined in EPA AP-42, Volume I, Chapter 13.2.2. As vehicles travel on unpaved surfaces, particles are created (via pulverization), lifted and dropped by the wheels. These particles can become entrained in the vehicle's turbulent wake as it passes and can then be transported to varying degrees away from the point of origin.

Fugitive dust emissions factors are estimated via engineering equations (developed from empirical data analysis) for each specific pollutant being analyzed (PM10 and PM2.5). Emission factors for fugitive road dust for travel on public roads are calculated using Equation 1 and emission factors for fugitive dust from travel on industrial roads are calculated using Equation 2.

Equation 1 - Public Road Fugitive Dust Emissions Factor

Where:

Equation 2 - Industrial Road Fugitive Dust Emissions Factor

Where:

The mean vehicle speed (S) and weight (W) used in Equation 1 and Equation 2 above are determined for the overall fleet due to how the EFs are calculated (i.e. for all vehicles travelling the route, vs. the individual classes of vehicles). Equation 3 shows how the weighted average is calculated for all the vehicle classes listed for the project, where the weighting is based on the total number of trips each vehicle class makes.

Equation 3 - Weighted Fleet Mean Vehicle Parameters

Where:

Vehicle Miles Traveled (VMT) is calculated in EMIT, using Equation 4, by collecting location specific access data, specifically the primary and secondary routes (and their associated lengths) proponents would use to travel to the project site. These lengths are then scaled in accordance with the percentage of the road lengths that are dirt. Any roads (access, spur, or otherwise) developed as part of the project are assumed to be dirt, and are added to the calculated length. The round trip length is then calculated and this is multiplied by the total number of trips (per vehicle class).

Equation 4 - Vehicle Miles Traveled (dirt)

Where:

The general equation for calculating unpaved road fugitive dust is shown below in Equation 5. EMIT applies this calculation to each vehicle class provided by the user (to provide task / temporal speciation) and the individual results are then summed to calculate the total unpaved road fugitive dust emissions for the project.

Equation 5 - Unpaved Road Fugitive Dust Emissions

Where:

Fugitive Dust – Heavy Construction Operations

This section describes how EMIT estimates general heavy construction emissions due to earthwork for a construction project. This includes fugitive dust particulate matter emissions only and does not include tailpipe emissions from fuel combustion, which are calculated separately. Emission calculations for heavy equipment construction operations are based on AP-42, Volume I, Chapter 13.2.3 and 13.2.4 methodology. Chapter 13.2.3 provides the base emission factor used for the fugitive dust from heavy construction operations in terms of total suspended particulate (TSP) while Chapter 13.2.4 provides the particle size multipliers that are used to convert the TSP emission factor to PM10 and PM2.5 emission factors.

Potential emissions associated with fugitive dust generated from land disturbance and associated wind erosion are based on an engineering calculation using emissions factors for heavy construction and user input to quantify the amount of land area disturbed by these operations and the duration of the disturbance. Fugitive dust emissions associated with heavy construction operations at a well pad include land disturbances that occur in creating the pad, building access roads where needed, and laying pipeline where appropriate. Emissions are calculated using Equation 6

Equation 6 – Fugitive Dust Emissions from Heavy Construction Operations (tons/well pad)

Where:

The total disturbed area (A_d) in Equation 6 is the sum of the disturbance area for each well pad, the disturbance for the access road needed for each well pad, and the disturbance area needed for pipeline construction associated with each well pad. This calculation is shown in Equation 7.

Equation 7 – Total Disturbed Area from Heavy Construction Operations (acres/year)

Where:

EMIT also calculates the rate of fugitive dust emissions from heavy construction operations in units of pounds per hour. These are calculated in Equation 8 for dust from well pad operations, Equation 9 for dust from access road operations, and Equation 10 for dust from pipeline operations.

Equation 8 – Rate of Fugitive Dust Emissions from Well Pad Operations (lb/hr)

Where:

Equation 9 – Rate of Fugitive Dust Emissions from Access Road Operations (lb/hr)

Where:

Equation 10 – Rate of Fugitive Dust Emissions from Pipeline Operations (lb/hr)

Where:

This calculation is used in the following EMIT modules:

• Fluid Minerals
• Solid Minerals
• Grazing
• Vegetation
• Forestry
• Travel
• Renewable Energy

On-Road Vehicle Exhaust and Evaporative Emissions

This section describes how EMIT estimates emissions from on-road vehicle exhaust from the combustion of fuel in on-road reciprocating internal combustion engines as well as vehicle evaporation processes. These emissions are estimated using pre-calculated emission factors obtained by running EPA’s Motor Vehicle Emission Simulator (MOVES2014a) model for a 2018 calendar year multiplied by the corresponding number of vehicle miles traveled (VMT).

The MOVES model uses inputs on meteorology, vehicle age, vehicle type, vehicle speed, fuel, and road classification to estimate emission factors. The model can be run using site-specific data or at a more regional level using typical information for the county. Given the impracticalities of running MOVES for every single BLM project, MOVES was run using typical county information simulating Roosevelt County, Montana to generate “typical” emission factors. A sensitivity analysis was completed to show that this method is reasonable.

The emission factors from MOVES used in EMIT account for the following emission sources:

• Running exhaust
• Crankcase running exhaust
• Evaporative fuel leaks
• Evaporative fuel vapor venting
• Evaporative permeation
• Refueling displacement vapor loss
• Refueling spillage loss

EMIT provides the ability to model gasoline passenger cars, gasoline or diesel passenger trucks, diesel single unit short-haul trucks, and diesel combination long-haul trucks. (MOVES contains more vehicle classes than those included in EMIT, but BLM determined these are the only vehicle classes that apply to BLM projects.) Emission factors are selected in EMIT from a look-up table based on the vehicle class selected in the Vehicle Data section of the ON-ROAD VEHICLES module form.

Vehicle miles traveled (VMT) is calculated in EMIT for each unique trip process, task, and vehicle class selected by the user (i.e., for each tab on the ON-ROAD VEHICLES module form with sufficient data entered). VMT is the product of the length of road a vehicle travels and the expected number of trips for that road length. EMIT calculates VMT by collecting location-specific access data, specifically the primary and secondary routes (and their associated lengths) proponents would use to travel to the project site. Any roads (access, spur, or otherwise) developed as part of the project are added to the calculated length. Additional trip lengths, beyond the primary and secondary access routes that the vehicle might travel to the project location to complete or provide resources for the associated task(s) are also included. All of these trip lengths are the one-way road lengths. These road lengths are summed and multiplied by 2 to obtain the total round-trip distance traveled and this round-trip length is then multiplied by the total number of trips (per vehicle class) to estimate the VMT for the vehicle class. Equation 11 shows this calculation.

Equation 11 – Calculation of Vehicle Miles Traveled

Where:

Emissions are calculated in terms of tons per task as shown in Equation 12 for each specified process, task, and vehicle class identified on the ON-ROAD VEHICLES module form. EMIT also calculates total project emissions from on-road vehicle exhaust in terms of tons per project. This result is obtained by multiplying the emissions calculated with Equation 12 by the scalar determined by the Scaling Selector chosen on the ON-ROAD VEHICLES module form.

Equation 12 – On-Road Vehicle Emissions (tons/task)

Where:

It should be noted that the MOVES emission factors do not change with geographical location in EMIT. The sensitivity analysis discussed above shows that this is a reasonable assumption. In addition, all road types for BLM projects are assumed to be “rural” rather than “urban”. This assumption is made because BLM projects do not typically occur in urban areas.

EMIT only quantifies total HAP, but the MOVES model includes emissions for some individual HAPs. The percentage of total HAP that can be used to estimate individual HAPs can be found in Table A-4.

This calculation is used in the following EMIT modules:

• Fluid Minerals
• Solid Minerals
• Grazing
• Vegetation
• Forestry
• Travel
• Renewable Energy

Non-Road Mobile Equipment – Exhaust and Evaporative Emissions

This section describes how emissions from exhaust and evaporative processes from non-road equipment are calculated with EMIT. (Fugitive emissions caused by non-road equipment are discussed in other sections.) These emissions are estimated using pre-calculated emission factors obtained by running EPA’s Motor Vehicle Emission Simulator (MOVES2014a) model for a 2018 calendar year.

This version of MOVES incorporates the NONROAD2008a algorithms for estimating emissions from non-road equipment. This model uses inputs on meteorology, vehicle age, vehicle type, fuel and roads to estimate emission factors. The model can be run using site-specific data or at a more regional level using typical information for the county. Given the impracticalities of running MOVES for every single BLM project, MOVES was run using typical county information to generate “typical” emission factors. A sensitivity analysis analysis was completed to show that this method is reasonable. The emission factors from MOVES account for the following emission processes:

• Running Exhaust
• Crankcase Running Exhaust
• Refueling Displacement Vapor Loss
• Refueling Spillage
• Evap Tank Permeation
• Evap Hose Permeation
• Diurnal Fuel Vapor Venting
• HotSoak Fuel Vapor Venting
• Running Loss Fuel Venting

The primary inputs for calculating emissions from non-road equipment are entered in EMIT by the user in the NON-ROAD EQUIPMENT module form. On this form, the entries for the process, task, non-road category, and equipment type combine to uniquely define the set of equipment for which emissions are being modeled. The inputs for non-road category and equipment type are used within EMIT to look up the appropriate emission factors. Note that the available equipment types will change based on the selection for the non-road category. For most projects, there will be multiple such combinations needed to account for all of the non-road equipment being used on a project. When using EMIT to calculate emissions from non-road equipment, the user should make a list of all the nonroad equipment pieces that will be needed, categorizing the equipment based on the available menu selections. Each different grouping of equipment should be modeled by adding additional tabs on the NON-ROAD EQUIPMENT module form to appropriately represent each of these groups.

Equation 13 shows how EMIT calculates emissions for each equipment class. This equation represents the per-task emissions. To obtain the total project emissions for this equipment class, EMIT multiplies the task-level emissions by the appropriate scalar input by the user in EMIT.

Equation 13 – Non-Road Mobile Equipment Emissions

Where:

The non-road horsepower-hours (NR_hpHrs) in Equation 13 represent the activity for the specified non-road engine type. Equation 14 illustrates how the non-road hp-hr term is calculated.

Equation 14 – Calculation of Horsepower-hours for Non-Road Mobile Equipment

Where:

Note that the NONROAD module in MOVES does not produce emission factors for CH4 and N2O. Even though emissions of CH4 and N2O are likely negligible compared to CO2, EMIT uses ratios of CH4/CO2 and N2O/CO2 from the MOVES ONROAD model to estimate CH4 and N2O emission factors for NONROAD sources. In addition, the NONROAD module does not produce emission factors for HAP. EMIT uses ratios of HAP/VOC from the MOVES ONROAD model to estimate HAP emission factors for NONROAD sources. The percentage of the total HAP emissions that can be used to estimate individual HAPs can be found in Table A-4.

This calculation is used in the following EMIT modules:

• Fluid Minerals
• Solid Minerals
• Grazing
• Vegetation
• Forestry
• Travel
• Renewable Energy

Drill Rig Emissions

This section describes how emissions from drill rigs are calculated with EMIT. EMIT enables the calculation of emissions from the primary drill rig engines, auxiliary engines, and associated boilers. All emission factors used in EMIT for drill rigs can be found in Appendix Table A-6.

The emission factors used to calculate emissions from the primary drill rig diesel engines and auxiliary engines are obtained from 40 CFR, Part 89, “Control of Emissions from New and In-Use Nonroad Compression-Ignition Engines.” When these engines are 2- or 4-stroke natural gas reciprocating internal combustion engines (RICE) fueled by natural gas, the emission factors are based on EPA’s AP-42, Section 3.2, Tables 3.2-1, 3.2-2, and 3.2-3, with the emission units from these tables converted from lb/MMBtu to g/hp-hr. Emission factors for new natural gas engines that are subject to New Source Performance Standards (NSPS) for stationary spark ignition internal combustion engines are obtained from Table 1 of 40 CFR Part 60 ” Standards of Performance for Stationary Spark Ignition Internal Combustion Engines.”

Emission factors from boilers associated with a drill rig are obtained from EPA’s AP-42, Section 1.4, Tables 1.4-1 and 1.4-2 for natural gas boilers and from AP-42, Section 1.3 for boilers fueled by diesel or propane. The emission factors used in EMIT assume that the boilers are less than 100 MMBtu/hr of heat input and that the fuel contains 15 ppm sulfur, where applicable. All emission factors used in EMIT for drill rigs can be found in Appendix Table A-6.

Drill Rig Primary Engines

Drill rig emissions are calculated using the total horsepower-hours of the primary drill rig based on the engine's power rating and the hours the drill rig is operated. This is calculated with Equation 15.

Equation 15 – Calculation of Horsepower-hours per Well for Primary Drill Rig Engines (hp-hr/well)

Where:

Equation 16 shows how EMIT calculates emissions for drill rig primary engines for the type of rig employed to complete the applicable portion of the drilling / completion / workover schedule, as selected on the DRILL RIGS module form for the Rig Type. This equation represents the total drill rig engine emissions for the selected rig type per well in units of tons per well. To obtain the total project emissions (tons/project) for this drill rig primary engine of the selected Rig Type, EMIT multiplies the emissions calculated using Equation 16 by the number of Project Wells Serviced, as entered on the DRILL RIGS module form. The Project Wells Serviced entry should represent the number of project wells that will be serviced by the rig. If that number is less than the total number of wells, an additional rig of the same type should be provided. For a split entry of the same type, EMIT assumes that the rigs will run simultaneously. EMIT estimates the maximum tons of pollutant per year using Equation 17. EMIT also calculates the rate of emissions from primary drill rig engines in terms of pounds per hour using Equation 18 and in units of grams per second using Equation 19.

Equation 16 – Drill Rig Primary Engine Emissions for Selected Drill Rig Type (tons/well)

Where:

Equation 17 – Drill Rig Primary Engine Emissions for Selected Drill Rig Type (max tons/year)

Where:

Equation 18 – Drill Rig Primary Engine Rate of Emissions for Selected Drill Rig Type (lb/hr)

Where:

Equation 19 – Drill Rig Primary Engine Rate of Emissions for Selected Drill Rig Type (g/s)

Where:

Auxiliary Engines on Drill Rig Platform

Auxiliary engine emissions are calculated using the total horsepower-hours of operation for the auxiliary engines. This is calculated with Equation 20.

Equation 20 – Calculation of Horsepower-hours per Well for Auxiliary Engines on Drill Rig Platform (hp-hr/well)

Where:

Equation 21 shows how EMIT calculates emissions from auxiliary engines used on drill rig platforms for the type of rig employed and the selected auxiliary engine fuel type and auxiliary engine emissions tier selected on the DRILL RIGS module form. This equation represents the total auxiliary engine emissions for the selected type of auxiliary engine per well in units of tons per well. To obtain the total project emissions (tons/project) for auxiliary engine emissions on the drill rig platform, EMIT multiplies the emissions calculated using Equation 21 by the number of Project Wells Serviced, as entered on the DRILL RIGS module form. The Project Wells Serviced entry should represent the number of project wells that will be serviced by the rig. If that number is less than the total number of wells, an additional rig of the same type should be provided. For a split entry of the same type, EMIT assumes that the rigs will run simultaneously. EMIT estimates the maximum tons of pollutant per year from auxiliary engines with Equation 22. EMIT also calculates the rate of emissions from auxiliary engines in terms of pounds per hour using Equation 23 and in units of grams per second using Equation 24.

Equation 21 – Emissions from Auxiliary Engines on Drill Rig Platform (tons/well)

Where:

Equation 22 – Emissions from Auxiliary Engines on Drill Rig Platform (max tons/year)

Where:

Equation 23 – Rate of Emissions from Auxiliary Engines on Drill Rig Platform (lb/hr)

Where:

Equation 24 – Rate of Emissions from Auxiliary Engines on Drill Rig Platform (g/s)

Where:

Boilers on Drill Rig Platform

The total boiler heat input used in calculating emissions from boilers on the drill rig platform is calculated with Equation 25.

Equation 25 – Calculation of Drill Rig Boiler Heat Input (MMBtu/well)

Where:

Equation 26 shows how EMIT calculates emissions from boilers used on drill rig platforms for the boiler fuel type selected on the DRILL RIGS module form. This equation represents the total boiler emissions for the selected fuel type per well in units of tons per well. To obtain the total project emissions (tons/project) from boilers on the drill rig platform, EMIT multiplies the emissions calculated using Equation 26 by the number of Project Wells Serviced, as entered on the DRILL RIGS module form. The Project Wells Serviced entry should represent the number of project wells that will be serviced by the rig. If that number is less than the total number of wells, an additional rig of the same type should be provided. For a split entry of the same type, EMIT assumes that the rigs will run simultaneously. EMIT estimates the maximum tons of pollutant per year from boilers with Equation 27. EMIT also calculates the rate of emissions from boilers in terms of pounds per hour using Equation 28 and in units of grams per second using Equation 29.

Equation 26 – Emissions from Boilers Used on Drill Rig Platform (tons/well)

Where:

Equation 27 – Emissions from Boilers Used on Drill Rig Platform (max tons/year)

Where:

Equation 28 – Rate of Emissions from Boilers Used on Drill Rig Platform (lb/hr)

Where:

Equation 29 – Rate of Emissions from Boilers Used on Drill Rig Platform (g/s)

Where:

These calculations are used in the following EMIT modules:

• Fluid Minerals

Stationary Engines

This section describes how EMIT estimates exhaust emissions from stationary engines. These include natural gas-fueled spark ignition engines as well as diesel-fueled compression ignition engines. The emission sources calculated include the engine exhaust and venting emissions that occur during engine start-up. Most of the inputs needed for the emission calculations are entered on the STATIONARY ENGINES module form in EMIT.

Engine Exhaust Emissions

Annual engine exhaust emissions from stationary engines are calculated in EMIT using Equation 30 in units of tons per year. Emissions from these sources over the life of the project, in tons per project, are calculated by multiplying Equation 30 by the Estimated Life of Project entry on the DEVELOPMENT DETAILS module form. Annual exhaust emissions per stationary engine in units of tons per engine are calculated by dividing emissions calculated with Equation 30 by the scaled number of stationary engines (N), as defined in Equation 30. Emission rates for stationary engines are estimated in EMIT using Equation 31 to obtain an emission rate in units of grams per second.

Equation 30 – Annual Exhaust Emissions from Stationary Engines (tons/year)

Where:

Equation 31 – Rate of Emissions from Stationary Engines (g/s)

Where:

Venting Emissions from Engine Start-up

Annual venting emissions from stationary engine startups are calculated in EMIT using Equation 32 in units of tons per year. Annual venting emissions per stationary engine in units of tons per engine are calculated by dividing emissions calculated with Equation 32 by the scaled number of stationary engines (N), as defined in Equation 32. Emission rates for venting during startups of stationary engines are estimated in EMIT using Equation 33 to obtain an emission rate in units of grams per second.

Equation 32 – Annual Venting Emissions from Stationary Engine Start-ups (tons/year)

Where:

Equation 33 – Annual Venting Emissions from Stationary Engine Start-ups (g/s)

Where:

These calculations are used in the Fluid Minerals module.

External Gas Combustion – Process Heaters

This section describes how to estimate exhaust emissions from combustion in process heaters or boilers needed for various activities.

Most of the inputs needed for the emission calculations are entered on the PROCESS HEATERS module form. Annual emissions from process heaters and boilers are calculated in EMIT using Equation 34 in units of tons per year. Emissions from these sources over the life of the project, in tons per project, are calculated by multiplying Equation 34 by the Estimated Life of Project entry on the DEVELOPMENT DETAILS module form. Annual emissions per process heater or boiler in units of tons per device are calculated by dividing emissions calculated with Equation 34 by the Scaled Number of Heaters (N). Emission rates for heaters and boilers are estimated in EMIT using Equation 35 to obtain an emission rate in pounds per hour or with Equation 36 to estimate emission rates in units of grams per second.

Equation 34 – Annual Emissions from Heaters (tons/year)

Where:

Equation 35 –Emission Rate from Heaters (lb/hr)

Where: