Environmental Re-Evaluation

Findings from the updated environmental review are consistent with the Final Environmental Impact Statement

WSDOT and the Federal Highway Administration (FHWA) conducted a Re-Evaluation to determine if the Phase 1 Improvements created any new or significant effects compared to those described in the 2003 Final Environmental Impact Statement and Record of Decision. The team submitted a National Environmental Policy Act (NEPA) Re-Evaluation to FHWA for approval. The NEPA Re-Evaluation includes the following information about the project:

  • Social/environmental justice
  • Noise and air quality
  • Wetlands
  • Land use

  • Economics, public resources
  • Parks and recreational resources
  • Transportation/planning

Why was a Re-Evaluation conducted?

WSDOT and FHWA conducted a detailed review of the project, documented in the 2003 Final Environmental Impact Statement (EIS) and Record of Decision (ROD). Since 2003, some project elements have changed and WSDOT’s Re-Evaluation analyzed whether there were any new or significant impacts. Overall, the Re-Evaluation finds that the 2003 Final EIS and ROD remain valid and no new significant adverse effects were identified.

Key differences between what was studied in the 2003 Final EIS and ROD and the 2017 Phase 1 Improvements, include:

  • The 2003 Final EIS and ROD for the SR 509 Completion Project identified a six-lane improvement that included two general purpose lanes and one high-occupancy vehicle (HOV) lane northbound and southbound on SR 509. It also included interchange connections at South 188th Street, South 200th Street, 24th/28th Avenue South, I-5, SR 516, Veterans Drive, and a new South Access Road to Sea-Tac International Airport.
  • In this Re-Evaluation, the Phase 1 Improvements include four general purpose lanes on SR 509 (compared to six lanes as analyzed in the 2003 Final EIS), and assumes that all lanes will be tolled using one electronic toll point. Interchange connections would occur at five locations (compared to six locations as analyzed in the 2003 Final EIS): South 188th Street, 24th/28th Avenue South, I-5, SR 516 and Veterans Drive. Through a practical solutions approach, other components of the Selected Alternative identified in the 2003 EIS may be built.

What did the Re-Evaluation find?

Overall, the Re-Evaluation found that the 2003 Final EIS and ROD remain valid for the Phase 1 Improvements and no new significant adverse effects were identified.

  • Smaller project footprint.
    The 2018 Phase 1 Improvements were developed through the environmental review process. The Phase 1 Improvements are 78-feet wide as compared to 120-feet wide in the 2003 Selected Alternative. Therefore, there are fewer impacts on vegetation, wildlife, fish, parks and recreational resources.

Figure 3
Overlay comparison of 2003 Selected Alternative and 2018 Phase 1 Improvements

SR 509 completion project Federal EIS preferred alternative
SR 509 Completion Project 2003 Final EIS

SR 509 completion project phase 1
SR 509 Completion Project Phase 1 Imporovements

  • Addresses stormwater.
    Phase 1 Improvements would result in less new impervious surface area, approximately 50 acres as compared to the 113 acres that was estimated in the Final EIS. Runoff from the new and replaced roadway surfaces would be detained and treated. This is better than the 2003 Final EIS.
  • Consistent with regional plans.
    The improvements identified in the Phase 1 Improvements are consistent with current local comprehensive plans and policies which continue to identify the project as a key element in the transportation system. The Puget Sound Regional Council’s (PSRC’s) Transportation 2040 also identifies the project as a new tolled corridor that is key to enhancing freight mobility.
  • Improved traffic.
    Traffic operations would improve with the Phase 1 Improvements. Both the 2003 Final EIS and the Re-Evaluation found that traffic congestion on I-5 would improve because traffic would shift to the new SR 509. However, the Phase 1 Improvements show a smaller shift in traffic compared to the 2003 Selected Alternative, because the Phase 1 Improvements includes tolling.
  • Less Noise impacts.
    The Phase 1 Improvements are expected to result in fewer noise impacts than the 2003 Selected Alternative.
  • Effects of tolling.
    The Re-Evaluation considered the effect that tolling would have on low-income and minority populations. The analysis found that I-5 and surrounding arterials would remain accessible alternatives to the new tolled facility. The new SR 509 is expected to offer improved travel times, compared to if the Phase 1 Improvements were not built.
  • Fewer property acquisitions.
    Phase 1 improvements identify 88 parcels for acquisition in comparison to 133 parcels identified in the 2003 final EIS.