Tunneling on Ballard Siphon Replacement project expected to be completed this week

Tunneling on the Ballard Siphon Replacement project is expected to be completed this week, according to King County. The tunneling started over a year ago on the siphon replacement, a project to build a new 85-inch siphon pipe under Salmon Bay between Ballard and Interbay. The new siphon will prevent sewer overflows into Salmon Bay and sewer backups in North Seattle.


Image courtesy King County

The 2,000-foot tunnel underneath Salmon Bay is expected to be completed this week, and crews will shift to the north end of the project site on Shilshole to complete the tunnel and remove the boring machine from the 93-foot deep shaft.

Work that still needs to be completed includes relining the existing siphon (westbound traffic on Shilshole Ave NW detour to occur during this time), connecting the new siphon to the conveyance and test systems, and completing north and south site restorations. King County expects the four-month Shilshole Ave NW detour will begin in early to mid-October, with the project completion in mid-2014.

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Map of upcoming detours (Courtesy King County)

During the four-month work at the north site, drivers and residents can expect a high level of activity involving crews, equipment, and trucks, and increased truck traffic on Shilshole Ave NW. The sidewalk along Shilshole will be closed in front of the project site.

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