From staff reports:

Underground plumbing work will close two lanes of southbound Interstate 5 at State Route 161 (Enchanted Parkway) in Federal Way this weekend.

Crews will begin closing lanes at 8 p.m. Friday and reopen them by 6 a.m. Monday.

Starting at 8 p.m., the southbound I-5 HOV lane, just north and south of the SR 161 overpass, will be closed to drivers. Then, the far-left lane will close at 10 p.m. in the same area. Both lanes will remain closed through the weekend and reopen by 6 a.m. Monday.

During the closure, construction crews will extend an existing drainage system and install a new pipe under southbound I-5. This work will help manage increased water runoff from a series of new flyover ramps at the Federal Way Triangle, the interchange where I-5, SR 161 and SR 18 meet.

Drivers should plan for delays, and keep an eye on current traffic conditions by checking the Seattle traffic map, or downloading the WSDOT mobile app.