Infiltration Testing, Design, and Mounding Analysis for Effective Stormwater Management for a New Link Light Rail Extension Project in Washington State

The Downtown Redmond Link Extension project is a major extension of the regional light rail system within the Puget Sound area of Washington State. Because of the prevailing site conditions and design philosophy as well as the shallow groundwater and flat topography, managing stormwater was a major design element of the project and required a complex system of collection and distribution network of infiltration facilities. Careful analyses and design were therefore necessary for creating the infiltration system to manage stormwater using multiple facilities in a highly developed area with a shallow groundwater table while mitigating adverse impacts of flooding. The stormwater management solution achieved in this project illustrates a successful outcome from a close and continuous coordination among geotechnical, civil, and stormwater engineers.