I-5 – SR 510 Diverging Diamond Interchange

Location: Lacey, WA
Owner: Washington State Department of Transportation

Construction Bid Opening Date: August 22, 2018

OCI designed the stormwater and temporary sediment and erosion control elements for this WSDOT Design-Bid-Build project located at the I-5/SR 510 (Marvin Road) interchange in the City of Lacey. The project will upgrade the existing interchange to a Diverging Diamond Interchange (DDI) and add a southbound frontage road to accommodate future growth in the area. The proposed DDI is the first of its kind in the State of Washington, and as such it presented several unique challenges. As the drainage lead for the project, OCI implemented several flow control and water quality best management practice (BMP) designs to minimize downstream impacts of runoff from new pavement areas. These design elements included six infiltration ponds, five bioswales for runoff treatment, 9,000 linear feet of storm drain and several ditch conveyance systems. OCI maximized the use of on-site BMP systems at the interchange within existing right-of-way limits through the evaluation of existing soil and groundwater conditions. This has been an exciting project to design for the State of Washington and we look forward to seeing it constructed!

The DDI design is proven to improve safety by reducing conflict points, decrease wait times at signals, and increase traffic flow.  Construction is scheduled to begin in the fall of 2018 and be completed in 2020.

For more information about WSDOT’s I-5/SR 510 DDI Project, click here, and for more information about the DDI design concept, click here.

Conceptual image courtesy of WSDOT

Roadway and Transit Drainage

Service Details >>

Services List
  • Stormwater Management and Design
  • Stormwater Detention, Infiltration, and Treatment Design
  • Hydrologic and Hydraulic Modeling
  • Stormwater Pollution Prevention Plan (SWPPP) and Narrative
  • Temporary Erosion and Sediment Control (TESC) Plans
  • Green Streets and On-Site Stormwater Management Approaches
  • Bridge Scour Analysis
  • Highway Runoff Dilution and Loading Stormwater (HI-RUN) Model
  • Culvert Analysis and Design
Service Contact
Deepa Mungasavalli Prabhu, PE
Practice Lead

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