Concrete in sewer line causes emergency repairs, South Lake Union traffic tie ups

The already horrible congestion around South Lake Union is about to get even worse, because the city will have to spend at least a month repairing a sewer line accidentally blocked by concrete from a construction project.

The Seattle Department of Transportation says work will begin Thursday to tear up Fairview Avenue North just south of Mercer.

Seattle Public Utilities (SPU) discovered concrete somehow poured into the sewer line and blocked it, SPU spokesman Cornell Amaya says.

A closed circuit camera probe determined the concrete had filled a 70-foot-long section of the pipes under Fairview between Harrison and Thomas Streets, KING 5 first reported.

The street has already been snarled by months of construction related detours and closures.

The repairs are expected to cost over $300,000. Amaya says the department will try and trace the source of the concrete based on its unique chemical composition. If investigators can find a match with a current or recent project, they’ll try and force the contractor to pay for it.

“We very much would like the people at fault to pay for it,” he says.

Crews were able to divert sewage blocked by the concrete to a nearby sewer line.

While it’s not uncommon to find sewer lines blocked by cement grout accidentally injected into sewer lines, it’s rare to find actual hardened concrete, Amaya says.

Traffic on Fairview will be reduced to one lane in each direction during the repairs, which are expected to take up to five weeks.