The project will construct a large diameter interceptor stormwater pipeline and build a new outfall into the Thea Foss Waterway. This project will improve existing storm sewer and system capacity, help reduce flooding events, and support future growth in the downtown area.

The existing surface water conveyance system in the downtown core does not have sufficient capacity to convey the runoff generated during significant rain events. The project involves construction of a new surface water interceptor and a new outfall or retrofit an existing outfall for additional capacity. Collectively, these improvements are referred to as the Jefferson and Hood Street Surface Water Interceptor Project.

The planned improvements include approximately 3,000 feet of new 48-inch and 72-inch diameter storm water interceptor pipe, including crossings of the BNSF rail corridor and a major City arterial/light-rail corridor, both of which are anticipated to be tunneled, as well as, a new surface water outfall or retrofits to an existing outfall and associated conveyance piping.

The project has completed Stage 1 – Design Phase. Stage 2 – Construction is planned to start October 2021.

Most of the sewer pipe will be installed using open-cut construction with a few areas that require microtunneling.


City of Tacoma




Alternative Delivery, Tunneling