South Link Light Rail and Angle Lake Station

Sound Transit/Huitt-Zollars

SeaTac, Washington

Sound Transit Angle Lake Station
We conducted site explorations and preliminary geotechnical engineering and infiltration design for this 1.6-mile segment of elevated track guideway. The project extends from Airport Station to South 200th Street and includes the Angle Lake Station and parking garage. We completed over 30 borings along the alignment and provided preliminary design recommendations for drilled shaft foundations (elevated guideway and station) and shallow footings (parking garage). We also identified areas favorable for stormwater infiltration and provided a preliminary design infiltration rate for the design.

Particularly challenging was obtaining subsurface information in areas with high traffic and many buried utilities. We coordinated with the Port of Seattle for explorations in the Sea-Tac Airport area, the City of SeaTac in the City’s right of way, and nearly a dozen private property owners.

Hart Crowser prepared the geotechnical data report and geotechnical baseline report for the design-build procurement. We reviewed and provided input for the preparation of contract documents, including the Request For Qualifications and technical requirements in the Request For Proposal.

During the pre-bid phase, we helped Sound Transit’s geotechnical engineer review and respond to bidders’ questions and provide clarifications of geotechnical documents, including evaluation of Alternate Technical Concepts.

After the project was awarded to the design-builder, Hart Crowser was part of Sound Transit’s construction management team that was responsible for design review and construction Quality Assurance. We participated in weekly task force meetings and reviewed geotechnical design submittals. During construction, we provided periodic field verifications of the construction observation of drilled shaft installation and responded to Requests For Information.