Determine what type of analyses your project will require
WSDOT addresses air quality, energy, and greenhouse gas emissions from projects together because they often use the same tools, however each analysis has slightly different triggers.
Refer to the Analysis decision tree (PDF 257KB) to determine which types of analyses your project requires. If your WSDOT project needs an analysis, inform the Environmental Documentation and Permit Specialist assigned to your project.
- Air quality conformity - see list of exempt project types in WAC 173-420-110
- Mobile source air toxics (MSAT) emissions
- Greenhouse gas (GHG) emissions
- Energy
Conduct and document analyses & prepare NEPA documentation
Air quality, greenhouse gas, and energy guidance (PDF 564KB) – Follow this guidance to ensure your analysis and documentation meet all requirements.
Conformity
Projects in air quality maintenance or nonattainment areas must demonstrate conformity. Washington State has areas under maintenance plans for course particulate matter (PM10), fine particulate matter (PM2.5), and carbon monoxide (CO). Find general information about transportation conformity requirements at the Federal Highway Administration's (FHWA) Air Quality and FHWA Transportation Conformity sites.
Carbon monoxide
Projects in CO maintenance areas require a hot-spot analysis. Use the Washington State Intersection Screening Tool to complete these analyses. Contact Lindsay Taylor, Lindsay.Taylor@wsdot.wa.gov, for methodology assistance.
Particulate matter
Larger projects in particulate matter maintenance areas may meet the EPA description of a "project of air quality concern" and could require a hot-spot analysis. EPA offers direction on Project-Level and Hot-Spot Analysis on their website. Refer to Appendix B of EPA’s Transportation conformity Guidance for Quantitative Hot-spot Analysis in PM2.5 and PM10 Nonattainment and Maintenance Areas for descriptions of projects that may and may not require PM hot-spot analysis. If your project may be a project of air quality concern, contact Lindsay Taylor, Lindsay.Taylor@wsdot.wa.gov, for assistance with the interagency consultation process.
Mobile Source Air Toxics (MSAT)
For MSAT analyses, WSDOT follows FHWA's updated interim guidance. If your project includes road segments with more than 140,000 average annual daily traffic or has the potential to concentrate high levels of diesel particulate matter in a single location, a quantitative MSAT analysis may be required.
Refer to the FHWA MSAT Frequently Asked Questions for current information on determining if your project requires an MSAT analysis and how to complete the analysis.
Greenhouse Gas Emissions
Follow the WSDOT guidance on Project-Level Greenhouse Gas Evaluations Under NEPA and SEPA (PDF 293KB) to address greenhouse gases in project documentation. All WSDOT projects must follow this approach.
Find more information on addressing the changing climate on Cumulative effects & climate change.
Energy
Only projects being evaluated at the environmental impact statement (EIS) level require an energy analysis. Follow the Air Quality, Greenhouse Gas, and Energy Guidance (PDF 517KB) and include energy in the same report as air quality and greenhouse gas emissions.
Review contract documents for commitments
See Environmental Manual Chapter 600: Construction (PDF 335KB) of the for policy guidance on how to track and comply with commitments during final design and construction.
Fugitive Dust
Reference the Memorandum of Agreement with Puget Sound Clean Air Agency - Fugitive Dust (PDF 22KB) for projects within King, Kitsap, Pierce, and Snohomish counties. Refer to the Guide to Handling Fugitive Dust from Construction Projects (PDF 862KB) from the Associated General Contractors of Washington for additional information on fugitive dust best management practices.
