Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports (2020)

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D-1 A P P E N D I X D User’s Guide The Interactive NEPA Information Tool (INIT) ACRP 02 – 73 User’s Guide The opinions and conclusions expressed or implied by use of this software are those of the research team. They are not necessarily those of the Transportation Research Board, the National Academies, or the program sponsors. This software is for assistance only and all decisions must be made by the software user. Results must be verified by the appropriate Federal Aviation Administration (FAA) official. This software, the Interactive NEPA Information Tool or INIT, assists users in complying with the National Environmental Policy Act (NEPA) by helping to identify the appropriate NEPA documentation and guiding the user through the NEPA process and the associated environmental laws that fall under the NEPA “umbrella.” This program will also aid the user in estimating the “order of magnitude” costs of NEPA documentation. The program relies on user input about the airport, project, and environmental conditions associated with the project being studied. Users should have information readily available and may need obtain additional information as prompted by the program. This program requires Windows 7 or later.

D-2 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Installer Setup Wizard. Click on the Next button. The installation package will suggest a destination file for the software. The user may accept this location or type in another. Multiple files will be loaded into this destination. These include the Application file (ACRP_02_73), files needed during program execution, reference material, and samples. If previously installed you will be asked to repair or remove the installer. A new window will appear after installation or repair is selected. If previous versions have been installed it is recommended to delete the previous folder. Click Finish and the software is ready for use. I. INSTALL SOFTWARE Software installation is made simple by the use of an installation program named ACRP_ 02_73_Installer. This program may be in a folder of the same name or simply a single file. The user must first copy the folder containing this installation package or the file containing the installation package onto the computer or system that will be used. Double-clicking the file will begin the software installation. Note that some virus checkers may need to be turned off during installation. You must tell the computer to run the program if warnings appear. A window will open that welcomes you to the

User’s Guide D-3 II. OPEN AND BEGIN USING THE SOFTWARE Open the program’s directory folder and double click on the “ACRP_02-73.exe” file shown in Figure 1 to open the INIT program. The Introduction to INIT window shown in Figure 2 will appear. This window gives the user the option of going to the ACRP website to review the User’s Guide in the ACRP 02-73 Final Report. In addition to this User’s Guide, the Final Report provides detailed information on the NEPA process, lessons learned from interviews and case studies, and explanations of the logic and assumptions built into the INIT processing. The Final Report also contains an extensive bibliography of reference documents addressing NEPA, special purpose laws, and environmental data sources. Selecting Open Interactive NEPA Information Tool opens the introductory window shown in Figure 3. The INIT takes the user through a series of windows providing a brief overview of the NEPA process. 3 2 1

D-4 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports After the first use, the user may also choose Skip Introduction by clicking on the button supplied. Clicking Next Page opens the window shown in Figure 4. The user can create a project by inserting the information and clicking Next, or retrieve an existing project by clicking Load Project. New projects are saved as a file in the same folder as the Application and will be available in later sessions by selecting Load Project. Selecting Next opens the window shown in Figure 5. The user can proceed directly to the generation of a cost and time estimate (Estimate) based on the user’s current understanding of the issues, or conduct the full analysis required to progress through the NEPA process by Selecting Analysis, which opens the Project Type Selection window described in Section III. Note that hovering with the cursor over the selection buttons brings up a pop-up note describing these options. 4 5

User’s Guide D-5 III. PROJECT IDENTIFICATION AND NEPA DOCUMENT TYPE The window shown in Figure 6 allows the user to select the project type or types that best represent the entire project from 47 possibilities. Clicking Next on the Project Type Selection window opens a window identifying other projects often associated with the selected project(s) (see Figure 7). All development needed for the project to function should be selected. In this example, hangar development was selected. Hangar development often includes associated projects needed to build or operate the hangar, which should be included in the environmental analysis, even if no ALP change or federal funding would be required if the associated project were undertaken by itself. Clicking on Auto Select adds all of the identified associated projects to the project being evaluated in the NEPA process. 6 7

D-6 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Note that some of the associated projects may not be eligible for approval as a CATEX if considered as a stand-alone project. For instance, there is no CATEX for “Detention Basin” and the INIT will warn the user if some of the selected projects are not eligible for approval as a CATEX. That warning will not prevent the user from completing the CATEX process, but it should alert the user to consider the effects of all required development in assessing the impacts of the complete project. The user may also click on Back to reconsider the selection of associated projects. Following the selection of any additional projects, the INIT opens one or more FAA Order 1050.1F CATEX eligibility windows corresponding to the project or projects selected. As an example, Figure 8 shows the window for accessory buildings including hangars. For each project type, INIT asks the user if the selected project conforms to the CATEX eligibility requirements of FAA Order 1050.1F. Selecting “Yes” indicates that the project may be eligible for approval as a CATEX, depending on the answers the user gives for the effects of the project. A “No” answer indicates that an EA or EIS would be required, although the INIT allows the user to continue the analysis. Selecting Next on the last FAA Order 1050.1F window or the Project Type Selection window brings up the Select Category window described in Section IV. 8

User’s Guide D-7 IV. ENVIRONMENTAL CATEGORIES AND ANALYSIS Figure 9 shows the window listing the environmental resource categories described in the FAA Environmental Desk Reference for FAA Order 1050.1F. Selecting any category opens a series of category-specific windows. Clicking on an individual category starts the series and is shown by the category being highlighted in the window. As an example, if Air Quality is selected, the window shown in Figure 10 appears. This window format is used for all categories. The left side of the window lists all of the categories that can be selected, while the right side shows a series of questions focusing on the selected category. In some cases, the choices are self-explanatory. In other cases, hovering the cursor over the menu options will activate pop-up notes to help the user determine the appropriate response. The completion bar at the bottom of the window provides a rough estimate of progress in this category. 9 10

D-8 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Clicking on More Information in this window or any window during the environmental analysis phase of the program opens a link to the ACRP 02-73 Quick Reference Table shown in Figure 11. This table provides additional links to references, documents and/or websites to assist the user in responding to the INIT questions. At any time during the evaluation, the user can review the progress in any category by double-clicking on it to expand the level of detail as shown in Figure 12. In this example, the warning signs in the Ecological Resources category indicate incomplete information in one or more elements. INIT allows the user to continue the evaluation but warns that the results may not be reliable. The user may also click on the Project Selection button at any time to go to the Project Type Selection window and click on the Generate CATEX button to view the inputs provided up to that point. 12 11

User’s Guide D-9 At the end of each category, INIT will ask if the user has finished the environmental questions (see Figure 13). Answering “No” brings the user back to the Select Category window. Answering “Yes” brings the user to the Project Type Selection screen window described in Section III, from which the user may select the Cost Estimate or Generate CATEX options (see Figure 6). 13

D-10 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports V. COST ESTIMATES Selecting Cost Estimate on the Project Type Selection window shown in Figure 6 takes the user to the Project Cost and Time Estimation sequence. The user must click the level of effort thought to be applicable. As an example, in the Air Quality window shown in Figure 14a the user has selected a “Medium” level of effort required to assess air quality impacts. The Associated Cost and Duration were generated as shown. Hovering the cursor over the menu options activates pop- up notes to help the user in determining the level of effort required for the analysis of environmental impacts. At any time, the user can click on Running Summary to view the cost and scheduling estimates based on the input to that point in the process as shown in Figure 14b. 14a 14b

User’s Guide D-11 Figure 15 shows a completed cost estimate. The user’s input for generating the cost estimates is saved as part of the case study. As noted on Figures 14 and 15, the user should take a window print or capture of the results for future reference. Selecting Continue brings up the window shown in Figure 6. Selecting Cost Analysis in that window again presents the Cost Estimate or Full Analysis Window (Figure 5) and selection of Analysis in that window brings up the Project Type Selection window (see Figure 6) that allows the user to select the “Generate CATEX” option described in Section VI. 15

D-12 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports VI. GENERATE CATEX Selecting Generate CATEX in the Project Type Selection window shown in Figure 6 takes the user to the user to the ACRP 02-73 NEPA Database Tool Output Form, which is an editable Microsoft Word document formatted to reflect the FAA Airports Division Standard Operating Procedure (SOP) 5.0 for CATEX Determinations. Note that the Airports Division updates the CATEX SOP to reflect changes in the underlying FAA Order 1050.1 and 5050.4 series. The current CATEX SOP Version 5.10, effective June 2, 2017, is available at the FAA website address below. https://www.faa.gov/search/?omni=MainSearch&q=CATEX The ACRP 02-73 NEPA Database Tool Output Form reflects the user’s selections described in Sections III and IV of this guide. The user’s narrative comments are shown in red font to distinguish them from the narrative in the form itself. The user can edit comments entered in the Project Identification and NEPA Document Type and the Environmental Categories and Analysis windows. The user can at any time copy the information provided in the Output Form and paste it into the current version of the Airports Division CATEX form. The following pages show the output of a test case. Note that the sample answers are not based on an actual situation and do not provide the level of detail that may be required to meet the requirements of an FAA reviewer. ACRP 02-73 NEPA Database Tool Output Form Airport sponsors should use this form for projects eligible for a categorical exclusion (CATEX) that have greater potential for extraordinary circumstances or that otherwise require additional documentation, as described in the Environmental Orders (FAA Order 1050.1F and FAA Order 5050.4B). To request a CATEX determination from the FAA, the sponsor should review potentially affected environmental resources, review the requirements of the applicable special purpose laws, and consult with the FAA Environmental Protection Specialist about the type of information needed. The form shown in the Sample Results Document should be completed and sent with any supporting environmental resource documentation to the appropriate FAA Airports Division/District Office. The form and supporting documentation should be provided in accordance with the provisions of FAA Order 5050.4B, paragraph 302b, to allow sufficient time for review. The CATEX cannot be approved until all information/documentation is received and all requirements have been fulfilled. It is ultimately the sponsor’s responsibility to ensure that all of the information necessary for the FAA to make an environmental determination is accurate and complete.

User’s Guide D-13 Name of Airport: GA Reliever, LOC ID: TST Project Title: Test Run Provide a brief, but complete description of the proposed project, including all project components, justification, estimated start date, and duration of the project. Include connected actions necessary to implement the proposed project (including but not limited to moving NAVAIDs, changing flight procedures, and designating or developing haul routes, new material or expanded material sources, staging or disposal areas). Attach a sketch or plan of the proposed project. Photos can also be helpful. Description: Hangar with associated improvements. Provide a brief, but complete, description of the proposed project area. Include any unique or natural features within or surrounding the airport property. Hangar and associated development at GA Reliever Airport Identify the appropriate CATEX paragraph(s) from Order 1050.1E (paragraph 307- 312) or 5050.4B (tables 6-1 and 6-2) that apply to the project. Describe if the project differs in any way from the specific language of the CATEX or examples given as described in the Order. FAA Order 1050.1F: 5-6.4.f,h; FAA Order 1050.1F: 5-6.4.e; FAA Order 1050.1F: 5- 6.4.i; FAA Order 1050.1F: 5-6.4.k,l,o; FAA Order 1050.1F: 5-6.4.j. The circumstances one must consider when documenting a CATEX are listed below along with each of the impact categories related to the circumstance. Use FAA Environmental Orders 1050.1E, 5050.4B, and the Desk Reference for Airports Actions, as well as other guidance documents to assist you in determining what information needs to be provided about these resource topics to address potential impacts. Indicate whether or not there would be any effects under the particular resource topic and, if needed, cite available references to support these conclusions. Additional analyses and inventories can be attached or cited as needed.

D-14 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports 304a. National Historic Preservation Act (NHPA) resources Projects that have the potential to cause effects on historic properties require a Section 106 finding in order to meet the requirements of the NHPA regardless of the type of NEPA document being completed. Check with your local Airports Division/District Office to determine if a Section 106 finding is required. Consultation with the State Historic Preservation Officer/Tribal Historic Preservation Officer (SHPO/THPO) may be required, and should be conducted through the FAA. National Historic Preservation Act Yes No Are there historic, or architectural sites on the project site? (FAA must determine if there is an undertaking) Buildings to be demolished are less than 45 years old. No other structures would be affected. No off-Airport impacts. Would project affect native soils or known archaeological/cultural resources? Area was previously disturbed. Does site constitute DOT 4(f)? Not applicable (based on previous responses in this case). 304b. Department of Transportation Act Section 4(f) and 6(f) resources DOT Section 4(f) Yes No Are there parks, wildlife preserves, public recreational uses or historic sites on or adjacent to the project site? Town Comprehensive Plan. Would the project displace all or part of a public land? No acquisition. Is effect de minimis? Not applicable (based on previous responses in this case).

User’s Guide D-15 Have alternatives to avoidance been considered? If a prudent and feasible alternative is available, FAA will not approve the alternative that affects 4(f). Not applicable (based on previous responses in this case). Have Land and Water Conservation Funds been used? Not applicable (based on previous responses in this case). Are there induced effects (i.e., noise air quality, traffic, etc.) on the property? No significant noise impacts. Would these effects rise to a constructive use? Not applicable (based on previous responses in this case). Have measures been incorporated to reduce effect? Not applicable (based on previous responses in this case). 304c. Natural, Ecological, or Scenic Resources This section covers a broad range of categories from farmlands to endangered species to coastal resources to wild and scenic rivers. Items to consider include: Coastal Resources Yes No Is the site in a Coastal Zone? Not in a coastal state. Is the project in or would it impact the Coastal Barrier Resource System? Not applicable (based on previous responses in this case). Ecological Resources Yes No Is there a possibility of federally threatened or endangered species and/or critical habitat within the project area? The project would be built on previously disturbed area.

D-16 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Is the Proposed Action likely to affect federally-protected species/critical habitat? Note: A Survey is required to properly answer this question. Not applicable (based on previous responses in this case). Note that response above may not be satisfactory as noted by warning sign in INIT program. Is there a possibility of migratory bird species and/or habitat within the project area? No trees on the property. Is there a possibility of essential fish habitat within the project area? No water bodies in the area. Farmland Yes No Is there prime, unique, state or locally important farmland in/near the project area? (Potential direct/indirect effects) No agricultural uses on the Airport, which was established prior to the Farmland Protection Act. Does the project include the acquisition and conversion of farmland? If farmland will be converted, describe coordination with the US Natural Resources Conservation and attach the completed Form AD-1006. No acquisition. Floodplains Yes No Would the project be located in, encroach upon or otherwise impact a floodplain? FIRM maps show no floodplains in the area.

User’s Guide D-17 Wetlands and Other Waters of the U.S. Yes No Are there any wetlands or other waters of the U.S. in or near the project area? No water bodies that could support wetlands vegetation. (Note that response above may not be satisfactory as noted by warning sign in INIT program.) Wild and Scenic Rivers Yes No Is there a river on the Nationwide Rivers Inventory, a designated river in the National System, or river under State jurisdiction (including study or eligible segments) near the project? NEPAssist website shows the closest segment to be 50 miles away. Will the project directly or indirectly affect the river or an area within 1/4 mile of its ordinary high water mark? Nearest designated wild/scenic river segment is 50 miles away. 304d. Disruption of an Established Community Disruption of Established Community Yes No Are there minority and/or low-income populations in/near the project area? Census data show that minorities and low income populations are found in the surrounding areas. Will the project require acquisition of off-airport businesses? All work to be on-Airport.

D-18 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Environmental Justice Yes No Are there minority and/or low-income populations in/near the project area? Census data indicate that minority and low income populations are present in the surrounding community. Would minority and/or low income populations be disproportionately affected? No acquisition and no off-Airport impacts. 304e. Surface Transportation Surface Transportation Yes No Will the project close a roadway or roadway lane or relocate a roadway? Temporary closure of entrance roadway. Will roadway change(s) lower the Level of Service on the roadway below acceptable standards? Consultation with Town Public Works Department. Does a traffic study show that the project would reduce Level of Service below acceptable levels? Not applicable (based on previous responses in this case). Is roadway an arterial or highway? Not applicable (based on previous responses in this case). Is mitigation proposed to maintain acceptable levels? Not applicable (based on previous responses in this case). Has formal coordination with the agency responsible for the roadway determined mitigation to be acceptable? Not applicable (based on previous responses in this case).

User’s Guide D-19 304f. Noise Noise Yes No Would the project result in an increase in aircraft activity or nighttime operations, or change fleet mix? Additional helicopter activity expected. Would the project change airfield configuration, runway use, or flight patterns either during construction or after implementation? No change in Airport operations. Have Substantial Noise Complaints occurred? Minimal complaints over the course of a year. Has a noise analysis been conducted, including but not limited to generated noise contours, a specific point analysis, area equivalent method analysis, or other screening method. If yes, provide that documentation. Prepared AEM analysis - less than 17% increase in 65 DNL contour area. Could the project have a significant impact (DNL 1.5 dB or greater increase) on noise levels over noise sensitive areas within the 65+ DNL noise contour? AEM analysis. Could noise impact be satisfactorily mitigated? Not applicable (based on previous responses in this case). 304g. Air Quality Air Quality Yes No Is the project located in a Clean Air Act non-attainment or maintenance area? Review of NEPAssist webpage.

D-20 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports If the project is located in a Clean Air Act non-attainment or maintenance area, is it listed as exempt, presumed to conform or will emissions (including construction emissions) from the project be below de minimis levels? (Provide the paragraph citation for the exemption or presumed to conform list below, if applicable.) Is the project accounted for in the State Implementation Plan or specifically exempted? Applicability analysis conducted for construction emissions. No further analysis required. Does the project have the potential to increase landside or airside capacity, including an increase in surface vehicles? No expected increase in aircraft operations. Could the project impact air quality or violate local, State, Tribal or Federal air quality standards under the Clean Air Act Amendment of 1990? Not applicable (based on previous responses in this case). Could the project impact air quality or violate local, State, Tribal or Federal air quality standards under the Clean Air Act Amendment of 1990? Previous analysis indicates that no air quality standards would be violated. 304h. Water Quality Airport projects may cause water quality impacts due to their proximity to waterways. Airport related water quality impacts can occur from both point and non-point (storm water runoff) sources. Water Resources Yes No Are Water Resources in or near the Project Area? No water bodies in the area. Will the project impact any of the identified water resources? Not applicable (based on previous responses in this case).

User’s Guide D-21 Will project increase storm water runoff? Not applicable (based on previous responses in this case). Does the project have the potential to violate federal, state, tribal or local water quality standards? Not applicable (based on previous responses in this case). Are any permits required? If yes, list the appropriate permits. Not applicable (based on previous responses in this case). 304i. Highly Controversial on Environmental Grounds Highly Controversial on Environmental Grounds Yes No Have federal, state, or local government agencies, a Native American tribe, or substantial numbers of the persons objected on environmental grounds? No significant off-Airport effects expected. 304j. Inconsistent with Federal, State, Tribal or Local Law Inconsistent with Federal/State/Local Laws Yes No Will the project be inconsistent with plans, goals, policy, zoning, or local controls that have been adopted for the area in which the airport is located? Is the project incompatible with surrounding land uses? No off-Airport impacts. 304k. Lighting, Visual, Hazardous Materials, Construction Impacts, Etc. Light Emissions and Visual Effects Airport related lighting facilities and activities could affect surrounding light- sensitive areas such as homes, parks, recreation areas, etc. Visual effects deal broadly with the extent to which airport development contrasts with the existing environment/setting.

D-22 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Light Emissions and Visual Effects Yes No Will the proposed project produce light emission impacts? Hangar and ramp will have security/safety lighting. Lighting would not be directed off-Airport. Will there be visual or aesthetic impacts as a result of the proposed project and/or have there been concerns expressed about visual/aesthetic impacts? New development will be similar in appearance to existing Airport structures. Hazardous Materials Federal, State, and local laws regulate hazardous materials use, storage, transport or disposal. Disrupting sites containing hazardous materials or contaminates may cause significant impacts to soil, surface water, groundwater, air quality, humans, wildlife, and the organisms using these resources. This category also includes solid waste and hazardous substances. Hazardous Materials Yes No Does the project involve or affect hazardous materials? None known. If any are encountered, the contractor will stop construction and take corrective action. Will construction take place in an area that contains or previously contained hazardous materials? None listed. If the project involves land acquisition, is there a potential for this land to contain hazardous materials or contaminants? No acquisition. Will the proposed project produce hazardous and/or solid waste either during construction or after? If yes, how will the

User’s Guide D-23 additional waste be handled? Construction would involve fuels and other construction materials classified as hazardous. Use of best management practices would minimize potential impacts. Construction Construction may cause various environmental effects including, but not limited to, increases in dust, aircraft and heavy equipment emissions, storm water runoff, spill/leaking petroleum, and noise. Construction Yes No Will the project result in construction impacts, such as reducing local air quality, increase erosion, pollutant runoff, or noise, disrupt local traffic patterns? If yes, describe measures to avoid and minimize construction impacts. Use of best management practices would minimize potential impacts. Will the project create short term impacts? Minor impacts from construction vehicle activity. Will the project result in any long term/permanent impacts? No long term change in use of hazardous materials. Energy Supply and Natural Resources Yes No Will the project change energy requirements or use consumable natural resources? Will the project change aircraft/vehicle traffic patterns that could alter fuel usage? No increase in aircraft activity anticipated and no change to airfield operations.

D-24 Guidance for Using the Interactive Tool for Understanding NEPA at General Aviation Airports Public Involvement Through public participation, federal agencies disclose information about a proposed project and expected environmental effects. Many of the special purpose laws (National Historic Preservation Act, Clean Water Act, etc.) require public notice and the opportunity for public involvement. User to insert discussion of any public outreach. Indirect/Secondary/Induced Impacts Indirect/Secondary/Induced Impacts are caused by the action and are later in time or farther removed in distance, but are still reasonably foreseeable. They may include growth inducing effects and other effects related to induced changes in the pattern of land use, population density or growth rate, and related effects on air and water and other natural systems, including ecosystems. Indirect Cumulative and Secondary Effects Yes No Would the project cause indirect, induced, or secondary impacts? No substantial change in Airport activity levels or employment. When considered in combination with other past, present, and reasonably foreseeable future projects, on or off airport property and regardless of funding source, would the proposed project result in a significant cumulative impact? Temporary increase in economic activity due to construction.

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S. DOT United States Department of Transportation

TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED ISBN 978-0-309-48102-1 9 7 8 0 3 0 9 4 8 1 0 2 1 9 0 0 0 0 N O N -PR O FIT O R G . U .S. PO STA G E PA ID C O LU M B IA , M D PER M IT N O . 88 G uidance for U sing the Interactive Tool for U nderstanding N EPA at G eneral A viation A irports A CRP Research Report 211 TRB