Westway and Imperium Expansion Projects

Draft Environmental Impact Statements
Air Fact Sheet

Construction and operation of the proposed facilities could affect air quality. Activities on the project sites and increased rail and vessel traffic would release air pollutants into the atmosphere.

What impacts on air quality were analyzed?

The studies looked at how air quality at the project sites, along the Puget Sound and Pacific (PS&P) rail line, and within Grays Harbor would be affected by the proposed projects. Air pollutants, including criteria pollutants, toxic air pollutants, and greenhouse gases are regulated by federal and state laws.

  • Criteria pollutants. The federal Clean Air Act identifies six criteria pollutants: ozone, particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead. Grays Harbor County currently meets the standards for all criteria pollutants.
  • Toxic air pollutants. Washington state law (Washington Administrative Code 173-460) identifies toxic air pollutants and sets limits for emissions. An example of a toxic air pollutant is diesel particulate matter, which is released when diesel fuel is burned.
  • Greenhouse Gases (GHG). Construction and operation of the proposed projects would emit greenhouse gases such as carbon dioxide. These gases trap heat in the atmosphere and contribute to climate change.

How were the impacts analyzed?

The following sources of air pollutant emissions were studied:

  • Equipment to construct the proposed facilities.
  • Operations at the terminals, including car traffic and rail car and vessel unloading and loading. Greenhouse gas emissions at the terminals were also considered.
  • Rail transport along the PS&P rail line. Greenhouse gas emissions along the rail route in Washington State were also considered.
  • Vessel transport to three nautical miles from the mouth of Grays Harbor.

The studies use this information to describe air resources. They consider the proposed construction, facility operations, and transportation by trains and vessels in Grays Harbor and along the PS&P line. Then they identify potential impacts on air resources or access to them from the proposed projects. Finally, the studies include actions that can mitigate or offset the potential impacts.

How will the proposed projects affect air quality?

Construction and Operations

Construction activities would emit pollutants. The studies found none of the pollutants are likely to exceed regulatory limits. Once in operation, the proposed projects would emit pollutants from tank cleaning and ship operations at the dock. Rail and vessel operations would also emit pollutants. The studies found these emissions would not exceed state and federal air quality standards. However, the amount of nitrogen oxides emitted from transportation would come close to the 1-hour standard.

Rail Traffic

Increased rail traffic would almost double the emissions of criteria pollutants associated with rail transport in the county. However, these emissions would be spread over the 59-mile PS&P rail line. The studies found that national and state standards would not be exceeded.

Increased rail traffic would also increase toxic air pollutants, primarily diesel particulate matter, which has been shown to increase the risk of cancer. Most diesel particulate matter would be emitted between Poynor Yard and the project sites. There is a chance that parks and some homes close to the project sites could be exposed to higher levels. Mitigation measures will be required to reduce the risk to these homes.

There are no schools, hospitals, daycare centers, assisted living facilities, or senior centers in the potentially affected area. Along the PS&P rail line, emissions would not be concentrated in any one area. Also, risk of exposure would be further reduced when new and more efficient rail locomotives are put into service. To ensure that air emissions do not exceed acceptable levels, Westway and Imperium will implement measures to monitor emissions of diesel particulate matter and implement mitigation measures.

Vessel Traffic

Vessel traffic in Grays Harbor would increase under the proposed projects. These vessels would travel along the Grays Harbor Navigation Channel and away from the shoreline. Emissions of air pollutants (primarily diesel particulate matter) would be spread out over the length of the navigation channel. The studies found emissions from vessels would not exceed state and federal standards.

Greenhouse Gases

Construction and operation of the proposed projects and associated rail and vessel transport would emit greenhouse gases. Total annual operational emissions for the Westway project, including rail and vessel transport within Washington State, equal nearly 7,600 automobiles. For the Imperium project, total emissions equal that of almost 12,800 automobiles. The total emissions for each facility represents less than 0.0013% of the national 2025 target and less than 0.1% of the state 2050 target to reduce greenhouse gas emissions. The studies also looked at greenhouse gases related to combustion. Section 3.2, Air, in Chapter 3 of the Draft EISs explains in more detail.

What can Westway and Imperium do to reduce impacts on air?

Permits and Plans

The proposed projects must comply with air permits issued by the Olympic Region Clean Air Agency. These permits set limits for emissions and require record keeping and reporting for stationary sources. The Notice of Construction Air Permit requires that the proposed projects use the best available technology to control emissions.

Mitigation Measures

The studies identify the following mitigation measures to reduce impacts on air:

  • Regularly inspect and maintain equipment, adopt an anti-idling policy, and ensure that equipment operators receive training on best practices for reducing fuel consumption.
  • Coordinate with the Port of Grays Harbor and PS&P to manage wait times for rail and vessel arrivals or departures.
  • Use more efficient switching engines to move rail cars from Poynor Yard to and from the proposed facilities. Engineers will also minimize idling of the locomotives to reduce emissions as much as possible.
  • Install monitoring stations to measure levels of diesel particulate matter, and submit annual reports to the City of Hoquiam. If levels become too high, the City will require Westway and Imperium to modify or reduce switching operations, or install special devices on switching engines to reduce emissions.
  • Install air monitoring stations to monitor the nitrogen dioxide emissions at or near the project sites and submit annual reports to the Olympic Region Clean Air Agency. If levels become too high, then additional measures could be required in the air permit.

The detailed list of measures is presented in Section 3.2, Air, of the Draft EISs

Where is more information available?

Within the Draft EISs, Section 3.2, Air, has detailed information on current conditions, analysis and findings related to the impacts of the proposed project on air quality. The following sections of Chapter 3 also include detailed information and analyses relevant to air: Section 3.15, Rail Traffic, and Section 3.17, Vessel Traffic.

There are additional fact sheets discussing Rail Traffic and Vessel Traffic.


Westway Terminal proposal
Imperium Terminal proposal

Port of Grays Harbor, Grays Harbor County at 46.9711N/123.859W

Ecology Point of Contact:
Diane Butorac
Regional Planner
Southwest Regional Office
Department of Ecology
(360) 407-6594


Open a printable version of this factsheet:

This fact sheet is provided as a general overview for public outreach purposes. This summary does not include all aspects of the analysis. The detailed analysis, data, and findings are in the Draft EIS for each proposal. The Draft EISs are the SEPA documents of record for information.


To request ADA accommodation for disabilities, or printed materials in a format for the visually impaired, call Hanna Waterstrat at 360-407-7668. Persons with impaired hearing may call Washington Relay Service at 711. Persons with speech disability may call TTY at 877-833-6341.