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Operations and Maintenance Facility South logo

Operations and Maintenance Facility South

On June 27, 2024, the Sound Transit Board selected the preferred alternative (South 336th Street Alternative) in Federal Way as the project to be built for the OMF South. The decision was informed by findings from the Final EIS, public and agency comments on the 2021 and 2023 Draft EIS documents, and other factors. Click here to watch the June 27 Sound Transit Board meeting recording.

Welcome

What's the latest?

Sound Transit and the Federal Transit Administration (FTA) have published a joint National Environmental Policy Act (NEPA)/State Environmental Policy Act (SEPA) Final Environmental Impact Statement (EIS) for the Operations and Maintenance Facility (OMF) South project after holding public comment periods for the 2021 SEPA Draft EIS and 2023 NEPA Draft/SEPA Supplemental Draft EIS.

Next steps for the project:

  • We expect the Sound Transit Board to select the project to be built as soon as June 27.
  • We expect FTA to issue its Record of Decision for the project in Q3 2024.
  • After the Record of Decision, Sound Transit will begin final design and construction for the project. Sound Transit is working towards an OMF South opening date between 2032-2037, depending on the alternative selected to be built.
    • Sound Transit is pursuing measures to advance the scheduled opening to as early as 2030. If the Midway Landfill alternative is selected as the project to be built, the opening date would be between 2035 and 2037, depending on the subsurface construction design option. We will share an updated project schedule when we have more certainty.

An OMF is where Link light rail trains go for cleaning, storage, and maintenance, 24 hours a day, 365 days a year. Sound Transit needs four strategically located OMF facilities to ease our planned service expansion. Two OMF facilities already exist (Seattle and Bellevue). We need this new OMF in the South Sound to receive, store, and service a larger train fleet to support future light rail extensions to Tacoma and throughout the region. To build this new facility, we need approximately 60-70 acres (for reference, one football field is 1.3 acres) near the Federal Way Link Extension (FWLE).

November 2016: Voter approval

Voters approved funding for 118 miles of Link light rail, including two new OMFs—one in the north corridor and another in the South Sound—to serve the growing light rail system.

Mid to late 2018: Initial community idea gathering and evaluation

After receiving community input during the early scoping outreach period in April 2018, Sound Transit named 24 potential OMF South sites for further analysis. After initial screening, we reduced the number of possible sites to 20. We assessed these 20 sites with a robust list of evaluation criteria, including project schedule, long-term facility planning, operational requirements, environmental impacts, and engineering risks, among other standards.

February to April 2019: SEPA Scoping

Based on the results of the detailed screening, we identified six sites in Kent and Federal Way for further consideration. The public had the opportunity to share their thoughts on the six potential sites, as well as the OMF South project Purpose and Need Statement and environmental resources to evaluate in the Draft EIS during the scoping comment period under the SEPA.

May 2019: Sound Transit Board action

After reviewing community feedback gathered during scoping and the thorough evaluation on the six potential sites, the Sound Transit Board identified three sites for further study in the Draft EIS:

  • Midway Landfill alternative (Kent)
  • South 336th Street alternative (Federal Way)
  • South 344th Street alternative (Federal Way)

Summer 2019 to 2021: SEPA Draft EIS

Sound Transit prepared a Draft EIS under SEPA to evaluate the potential impacts of the OMF South alternatives and share findings with tribes, agency and jurisdictional partners, and the public. We published the SEPA Draft EIS in 2021 and held a public comment period (engagement summary, comment summary).

December 2021: Sound Transit Board identified a preferred alternative

After the SEPA Draft EIS comment period, the Sound Transit Board considered the SEPA Draft EIS analysis and comments received and then identified the South 336th Street site in Federal Way as the preferred alternative, with all three sites still to be evaluated in a Final EIS.

December 2021 to July 2023: Project refinements

After the Sound Transit Board identified the South 336th Street site in Federal Way as the preferred alternative, we completed additional fieldwork activities and environmental analysis. We made additional design refinements to the preferred and South 334th Street alternatives.

September to November 2023: NEPA Draft/SEPA Supplemental Draft EIS

The Federal Transit Administration (FTA) and Sound Transit published a NEPA Draft/SEPA Supplemental Draft EIS that evaluated the same three alternatives as the 2021 SEPA Draft EIS with the design refinements. Sound Transit shared the Draft EIS with tribes, agency and jurisdictional partners, and the public through a 45-day public comment period (engagement summary, comment summary).

We are here: Final EIS

Sound Transit and FTA reviewed and responded to substantive comments received on the 2021 and 2023 Draft EIS comment periods and has published the Final EIS. The Sound Transit Board will select the project to be built as soon as June 27. After that, FTA will issue a Record of Decision to conclude the environmental review process.

Aerial view of the existing operations and maintenance facility in Seattle. This facility receives, stores and services Sound Transit’s Link light rail trains. The site includes a Link train storage building, offices for operations and controls, and a yard with Link trains lined up on tracks.

We service our current light rail trains at a central OMF on South Forest Street in Seattle.

The benefits of OMF South

  • Creates high-skilled, living-wage jobs for more than 610 people in South King County. At our existing OMFs, the average employee wage is $45 per hour, or $85,000/year
  • Ensures thousands of passengers can rely on clean, well-maintained trains.
A worker performs maintenance on a Link light rail train at the operations and maintenance facility in Seattle. The worker is inside the train making a repair to the overhead lighting with a screwdriver.

A worker at the existing OMF in Seattle conducts maintenance on a Link train.

 

 

Environmental review

What is an Environmental Impact Statement?

Before Sound Transit builds projects, we assess the potential effects of each project alternative on the natural and built environment in a document called an Environmental Impact Statement. The EIS helps decision-makers, the public, and our project partners evaluate the possible environmental impacts of each potential site during construction and operation. The EIS also compares the effects of each alternative to inform the public, agencies, and the Sound Transit Board.

In the OMF South Draft EIS (2021, 2023), we looked at how the Midway Landfill, South 344th Street, and South 336th Street alternatives would affect air and water quality, historical and cultural resources, property acquisition and land use, economic effects, hazardous materials, ecosystem resources, environmental justice, cost, schedule, and more. In addition to the EIS, we also conducted a Title VI Facility Equity Analysis to determine whether any of the facility location options would result in a disparate impact to populations based on race, color, or national origin (2021, 2024 addendum).

Equitable community engagement is integral to the success of the OMF South project. Read our OMF South Draft EIS Engagement Summaries (2021, 2023) to learn more about how we collected community input during both Draft EIS comment periods.

Final EIS now available

The Final EIS includes analysis of the alternatives studied in the Draft EIS and responds to substantive comments received on the Draft EIS. Learn how each alternative could affect air and water quality, historical and cultural resources, nearby properties, ecosystem resources, cost, schedule, and more.

The Final EIS is available for public review in a variety of formats and locations.

After publication of the Final EIS, the Sound Transit Board considers the EIS analysis, comments received for the 2021 and 2023 Draft EIS documents, and other factors, then selects the project to be built. After the selection, we expect the Federal Transit Administration to issue a Record of Decision. Sound Transit will then begin the next phase of the project—design and construction of the facility!

How to find the response to your Draft EIS comment in the Final EIS

To find your comment and the associated response, please visit the Final EIS documents webpage, navigate to "Appendix L," and click the document that corresponds to you (2021, 2023).

If you provided your name or organization name with your comment, you can find your comment by finding your name in the table of contents, or:

Alternatives

This section provides key features about each of the three alternatives, detailed in the Final EIS. Scroll through this section to learn key features for all alternatives and review key impacts in the next section of this website.

Overview map of the three alternatives for the Operations and Maintenance Facility South. The preferred alternative is located near 336th Street in Federal Way. We are also studying a 344th Street alternative in Federal way and the Midway Landfill alternative in Kent.
Click to enlarge PDF

Map showing the future Link light rail route from Angle Lake to Federal Way as well as potential future sites for the Operations and Maintenance Facility South. The Federal Way Link Extension is currently in the construction phase. The route from Angle Lake to Federal Way begins at the Angle Lake station in the north and continues south, passing through Kent and Des Moines before it terminates at the Federal Way Transit Center. The map also features potential locations where Sound Transit is looking to site an operations and maintenance facility in South King County. The preferred alternative is located near 336th Street in Federal Way. We are also studying a 344th Street alternative in Federal way and the Midway Landfill alternative in Kent.

 

Preferred alternative (South 336th Street)

On Dec. 16, 2021, the Sound Transit Board identified the South 336th Street alternative in Federal Way as the preferred alternative for OMF South.

Key features

  • The preferred alternative is in Federal Way, between South 336th Street and South 341st Place, and between I-5 and SR 99.
  • The site footprint is approximately 66 acres.
  • The preferred alternative includes about 1.4 miles of mainline light rail tracks. These tracks are necessary for the proposed Tacoma Dome Link Extension (TDLE) light rail alignment, which is undergoing environmental review.
  • The preferred alternative includes a test track to prepare new vehicles for service. The test track would run parallel to the mainline tracks.

We would need to construct 1.4-1.8 miles of additional track (also called “mainline” tracks) between the end of the Federal Way Link Extension (currently in construction) to the potential OMF sites in Federal Way—the preferred alternative at South 336th Street and the South 344th Street alternative—to transport light rail cars from the regional system to the OMF South.

If the Board selects to build the Midway Landfill alternative, we might build the mainline tracks in Federal Way later, if TDLE is constructed as proposed. TDLE is currently under environmental review.

The Midway Landfill site is next to the Federal Way Link Extension route, so aside from short connecting tracks to the facility (also called “lead” tracks), there would be no added light rail track needed for that alternative.

Before a new light rail vehicle can start carrying passengers, we test how it performs on the track. Since we have light rail service running on the mainline tracks most of the day, we currently do all vehicle testing during the short service window, generally between 1-5 a.m. Building a test track will allow us to test vehicles faster, readying them for service. After analyzing the best location for a test track in our system, we found that placing it near OMF South was the best fit technically and operationally.

A map of test track and access road associated with the preferred and South 344th Street alternatives in Federal Way.
A test track would run parallel to the connecting light rail tracks for the preferred alternative and South 344th Street alternative. | Click to enlarge
A map of the preferred alternative, South 336th Street alternative in Federal Way. The facility would be located at the Christian Faith Center and west of I-5 in Federal Way.

The preferred alternative at South 336th Street is located at the current Christian Faith Center in Federal Way. The site’s boundaries include South 336th Street to the north, I-5 to the east, South 341st Place to the south, and State Route 99 to the west. Current plans for the South 336th Street alternative site alternative include landscaped areas along the site borders as well as in the central portions of the site. The OMF Building would be built in the center of the site. The Link Storage Building would be located immediately south of the OMF Building. Parking lots would be located west of each of the buildings. The OMF yard and tracks would occupy the northern portion of the site. The Tacoma Dome Link Extension tracks run north and south along I-5.

Site layout of the preferred alternative at South 336th Street. This site layout includes an extension of 18th Place South. | Click to enlarge PDF

South 344th Street alternative

Key features

  • The South 344th Street alternative is in Federal Way, between South 336th Street and South 344th Street, and between I-5 and 18th Place South.
  • The site footprint is approximately 64 acres.
  • The South 344th Street alternative includes about 1.8 miles of mainline light rail tracks, which would be necessary for the TDLE.
  • This site would include a test track. The test track would run parallel and on the east side of the connecting light rail tracks.

We would need to construct 1.4-1.8 miles of additional track (also called “mainline” tracks) between the end of the Federal Way Link Extension (currently in construction) to the potential OMF sites in Federal Way—the preferred alternative at South 336th Street and the South 344th Street alternative—to transport light rail cars from the regional system to the OMF South.

If the Board selects to build the Midway Landfill alternative, we might build the mainline tracks in Federal Way later, if TDLE is constructed as proposed. TDLE is currently under environmental review.

The Midway Landfill site is next to the Federal Way Link Extension route, so aside from short connecting tracks to the facility (also called “lead” tracks), there would be no added light rail track needed for that alternative.

Before a new light rail vehicle can start carrying passengers, we test how it performs on the track. Since we have light rail service running on the mainline tracks most of the day, we currently do all vehicle testing during the short service window, generally between 1-5 a.m. Building a test track will allow us to test vehicles faster, readying them for service. After analyzing the best location for a test track in our system, we found that placing it near OMF South was the best fit technically and operationally.

A test track would run parallel to the connecting light rail tracks for the preferred alternative and South 344th Street alternative.
A test track would run parallel to the connecting light rail tracks for the preferred alternative and South 344th Street alternative. | Click to enlarge
A map of the South 344th Street alternative in Federal Way. The facility would be located south of the Christian Faith Center and west of I-5 in Federal Way.

The South 344th Street site alternative is located south of the current Christian Faith Center in Federal Way. The site’s boundaries include South 336th Street to the north, I-5 to the east, South 344th Street to the south, and 18th Place South to the west. Current plans for the South 344th Street site alternative include landscaped areas along the site borders and at the center of the site where the OMF Building is also located. The Link Storage Building would be located on the northern end of the site. Parking lots would be located north and south of the OMF Building. The OMF yard and tracks would occupy the southern and central portions of the site. The Tacoma Dome Link Extension tracks run north and south along I-5. The I-5 alignment alternative for that project continues elevated along I-5. The elevated Enchanted parkway alignment alternative for that project begins to curve southwest toward Enchanted Parkway after passing the southeast corner of the OMF site.

Site layout of the South 344th Street alternative | Click to enlarge PDF

Midway Landfill alternative

Key features

  • The Midway Landfill alternative is in Kent, between South 246th Street and South 252nd Street, and between I-5 and SR 99.
  • The site footprint is approximately 68 acres.
  • Due to its location along the Federal Way Link Extension line, the Midway Landfill does not include mainline tracks.
  • This site would not include a test track because of varying grades. We need the test track at street level and on relatively straight and flat terrain, making this location unsuitable for meeting minimum operational and construction requirements.

Building on top of a landfill is a unique and complex challenge. Sound Transit must address the likelihood that this ground will continue shifting and settling over time, which could affect the tracks, equipment and other infrastructure. To prevent settlement, Sound Transit is considering three methods to prepare the Midway Landfill site for possible OMF construction: Platform, Hybrid, and Full Excavation. Due to contaminated material, material removed from the Midway Landfill during construction would require disposal at another landfill facility equipped to accept contaminated waste. The material would be hauled by truck to a regional transfer facility and sent on by rail for disposal.

Platform

Construct an approximately 3.5-foot thick, 35-acre concrete platform on top of a new landfill cap to support the facility. The platform option would require removing some of the landfill and drilling approximately 700 concrete support shafts roughly 120-180 feet deep.

Graphic illustrating the Midway Landfill Platform construction method.
Click to enlarge

Hybrid

Excavate almost all the landfill and replace it with soil and a 1-foot thick, 30-acre concrete slab supported by beams to provide a new surface to build the OMF. The Hybrid option would also require approximately 300 drilled concrete support shafts roughly 140 feet deep.

Graphic illustrating the Midway Landfill Hybrid construction method.
Click to enlarge

Full Excavation

Remove and dispose of virtually all the landfill material and backfill with new soil. The Full Excavation option would not include concrete support shafts.

Graphic illustrating the Midway Landfill Full Excavation construction method.
Click to enlarge

There are three different site preparation options, each with varying impacts. These variations are why the Midway Landfill site has three values listed in the next section.

A map of the Midway Landfill alternative in Kent. The facility would be located on the Midway Landfill, west of I-5.

The Midway Landfill site alternative is located south of the future Kent and Des Moines station. The site’s boundaries include 244th Street to the north, I-5 to the east, South 252nd Street to the south, and State Route 99 to the west. Current plans for the Midway Landfill alternative site include the existing stormwater pond at the northern end of the site. Landscaped areas are present in the north, south, and middle of the site. The OMF Building would be built in the central eastern portion of the site. The Link Storage Building would be located on the west side of the site, closer to State Route 99. Both buildings would have adjacent parking lots. The OMF yard and tracks take up the most space in the central areas of the site. The Federal Way Link Extension tracks will run along the eastern edge of the project site along I-5.

Site layout of the Midway Landfill alternative | Click to enlarge PDF

Key impacts

You can explore this information as a downloadable PDF (available in English, Korean, Spanish, and Russian) in the Final EIS Executive Summary (English), and in the Final EIS (English). These documents are accessible for screen readers. Please contact us at OMFSouth@soundtransit.org or 206-398-5453 for additional accessibility resources.

Because of the need for the mainline tracks, the environmental impacts for the preferred and South 344th Street alternatives are shown as two numbers, representing the impacts for the site and the mainline tracks.

The legend shows the colors and symbols used to denote different alternatives shown in the key impact graphics. The Preferred Alternative is shown in blue, the South 344th Street Alternative is shown in red, and the Midway Landfill is shown in purple. The Midway Landfill Construction options are shown as “P” for Platform, “H” for Hybrid and “E” for Full Excavation.
Graphic comparing the initial construction estimate of each of the three site alternatives studied in the Draft EIS.
Click to enlarge
Graphic comparing the annual operating cost estimate of each of the three site alternatives studied in the Draft EIS.
Click to enlarge

*Estimates are to be used for comparisons between alternatives only and do not represent the project budget. The preferred alternative and South 344th Street alternative estimates are for the sites only and do not include costs for mainline tracks.

Graphic comparing the residential displacements of each of the three site alternatives studied in the Draft EIS.
Click to enlarge
Graphic comparing the business displacements of each of the three site alternatives studied in the Draft EIS.
Click to enlarge

** If neither Federal Way alternative (the preferred alternative or South 344th Street alternative) is selected to be built and the Tacoma Dome Link Extension (TDLE) is constructed as proposed, impacts from the mainline tracks could occur later in time. TDLE is currently under environmental review.

¹Includes GarageTown, comprised of ~60 owners.

Graphic comparing the community and social resource of each of the three site alternatives studied in the Draft EIS.
Click to enlarge
Graphic comparing the employee displacements of each of the three site alternatives studied in the Draft EIS.
Click to enlarge
Graphic comparing the wetland impacts of each of the three site alternatives studied in the Draft EIS.
Click to enlarge
Graphic comparing the stream impacts of each of the three site alternatives studied in the Draft EIS.
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Graphic comparing the forest impacts of each of the three site alternatives studied in the Draft EIS.
Click to enlarge

** If neither Federal Way alternative (the preferred alternative or South 344th Street alternative) is selected to be built and the Tacoma Dome Link Extension (TDLE) is constructed as proposed, impacts from the mainline tracks could occur later in time. TDLE is currently under environmental review.  

Graphic comparing the construction duration of each of the three site alternatives studied in the Draft EIS.
Click to enlarge
Graphic comparing the maximum daily construction truck trips for each of the three site alternatives studied in the Draft EIS.
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Next steps

What comes next for OMF South

The Sound Transit Board is scheduled to select the project to be built as soon as June 27. The decision will be based on findings from the Final EIS, public and agency comments on the 2021 and 2023 Draft EIS documents, and other factors. Board meetings are open to the public and public comment is accepted on action items. The Federal Transit Administration (FTA) is anticipated to issue a Record of Decision later in 2024 under NEPA. After this, the project will begin detailed design work and construction planning.

OMF South schedule*

June 7

  • Final EIS published

As soon as June 27

  • Sound Transit Board selects the project to be built

Q3 2024

  • FTA issues Record of Decision

2025

  • Begin final design and construction

2032-2037**

  • Forecasted in-service date

*Subject to change.

**Sound Transit is pursuing measures to advance the scheduled opening to as early as 2030. If the Midway Landfill alternative is selected as the project to be built, the opening date would be between 2035 and 2037, depending on the subsurface construction design option. We will share an updated project schedule when we have more certainty.

Link light rail trains are staged on maintenance platforms in the Link Storage Building. Stairs are provided on the platform so that workers can access both the top of the train and the underside of the train to perform routine maintenance.

Link light rail trains are parked on maintenance platforms in the Link Storage Building.