You might have noticed the setup for this already. From the city:

Seattle Public Utilities (SPU) is conducting emergency sewer repair work on the West Seattle Bridge/Fauntleroy Way SW ramp heading eastbound. From Friday, August 28th, at 7:00 pm to Sunday, August 30th, at 3:00 pm, SPU crews will be excavating as part of an emergency sewer-repair project. The inside eastbound lane will be closed during this time and drivers should allow extra time for their trips due to possible congestion in this area.

SPU crews will continue the work with roadway panel replacement the weekend of September 11. They plan to work from Friday, September 11th, at 7:00 pm to the afternoon of September 13.