Skip Top Navigation

SR 520 Bridge Program: I-5 to Medina Project Community and Environmental Benefits

 
Lake Washington wetland
What are the key environmental benefits?

How will WSDOT protect the Washington Park Arboretum?

Environmental process overview



What are the key environmental benefits of the I-5 to Medina project?


  • Has the least effects to the environment of the options studied. 
  • Treats stormwater to remove pollutants that currently flow into Lake Washington and improves conditions for aquatic life. 
  • Has the least park impacts of the options evaluated, and provides a new 3.9-acre public park on the Ship Canal as well as new public open space on highway lids. 
  • Reduces vehicle miles traveled on SR 520 by 5 to 10 percent annually and greenhouse gas emissions in the corridor by nearly 10 percent compared to No Build. 
  • Provides reliable transit connectivity throughout the corridor. 

toptop



How will WSDOT protect the Washington Park Arboretum?

We know that the Washington Park Arboretum is a regional treasure. We've designed the I-5 to Medina project preferred alternative to improve the Arboretum by:

  • Removing the existing SR 520 on- and off-ramps and the unused R.H. Thomson Expressway ramps, allowing us to restore the park area and reduce traffic through the Arboretum.
  • Raising the bridge profile on Foster Island to improve trail access and reduce noise for park users. 
  • Enhancing bicycle and pedestrian connections to the Arboretum with more open space on the expanded Montlake lid and a crossing beneath the roadway near East Montlake Park.  

We are continuing to examine measures to avoid and minimize effects to the Arboretum as we refine the preferred alternative.

We coordinated with the Arboretum and Botanical Garden Committee through the ESSB 6392 process. Our final Arboretum Mitigation Plan is available online.

toptop



Environmental process overview

There are four milestones in the I-5 to Medina Bridge Replacement and HOV Project environmental process:

1. Publish draft EIS. In the summer of 2006, WSDOT published a draft environmental impact statement (EIS) describing how the Bridge Replacement and HOV Project could affect the environment in the project area and how WSDOT would avoid, minimize and mitigate these effects.

2. Publish supplemental draft EIS. In January 2010, we published the supplemental draft EIS, which builds on the findings of the draft EIS. This is an interim document between the draft EIS and the final EIS. The supplemental draft EIS evaluated new design options proposed through the west side mediation process and more details about construction effects and mitigation.

3. Publish final EIS. In June 2011, we published the final EIS, which evaluates the preferred alternative includes a response to comments received on both the draft and supplemental draft EIS documents.

4. FHWA prepares Record of Decision. In August 2011, the Federal Highway Administration published the Record of Decision, a public document that describes the project’s course of action and specific mitigation measures. 


toptop