Viaduct passes inspection, but two piers need repair

There has been no additional settling of the Alaskan Way Viaduct, the state Department of Transportation reported today.

However, problems were found on one block.

The viaduct was closed last weekend for its six-month inspection, and while inspectors found no settling of the structure overall, WSDOT is concerned enough about an inch of settling discovered at two piers near Colman Dock last year, it will move forward with repairs.

"We are pleased with the results of this inspection, but the situation is still urgent," said Jugesh Kapur, the state bridge engineer. "We are moving ahead to make repairs in the area between Columbia Street and Yesler Way to strengthen several footings."

The weekend inspection of the 54-year-old highway found that the total amount of settling since the 2001 Nisqually earthquake remains at 4 ¾ inches, and it found no structural damage. But the state said the viaduct continues to show signs of aging and deterioration.

The state plans to replace the viaduct but has made no decision how to build a new one.

The repair of the two piers, estimated to cost $5 million, is one part of several improvements recently announced by Gov. Christine Gregoire on the south end of the viaduct. Work will begin in the fall and will involve drilling a series of steel tubes filled with concrete with a steel rod in the middle. They will support the existing column footings near Columbia Street and Yesler Way.

The tubes will reach through unstable fill dirt and into the stable glacial till soil, making a stronger column foundation and preventing further foundation settling, according to the DOT.

The work is expected to take five to six months to complete and will not require lane closures, but there may be some parking restrictions under the viaduct.

The next full inspection will be in the fall.

Over the weekend, crews also looked for and removed loose concrete; repaired potholes, expansion joints and bridge rails; and inspected lighting and ventilation systems in the Battery Street Tunnel.

Crews have been inspecting the viaduct every six months for evidence of movement since the earthquake.

WSDOT says repairs are needed if the viaduct settles a total of six inches — another 1 ¼ inches — since the 2001 earthquake.

Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com