Date:  Friday, October 31, 2008

Contact: Meghan Soptich, WSDOT Communications, 206-440-4704 (Seattle)
Dave Lindberg, WSDOT Project Engineer, 425-814-7104 (Redmond)

Thunder Hills Creek flowing through new culvert just in time for winter storms

RENTON – Today, crews finished installing a new culvert to carry Thunder Hills Creek underneath Interstate 405 in Renton. Crews have been working since December to replace a culvert that collapsed during record rain storms last winter.

“As of noon today, the creek was running through a new culvert under I-405,” said Project Engineer Dave Lindberg. “We’re very pleased to have the culvert in place before winter gets under way.”

Crews originally expected to finish replacing the culvert by the end of July, but were delayed when the boring machine used to push the steel pipe sections underneath I-405 became stuck. The project team developed a plan to recover the machine by tunneling from the east side of I-405 and work resumed in October.

Crews welded the 20-foot-long sections of steel pipe together to create a continuous, 320-foot-long pipe under the freeway. The new culvert is 51 inches in diameter. Crews will spend the next few weeks removing the pumps and piping that have diverted Thunder Hills Creek during the repair work.

“Taking down the pump system will take a couple of weeks,” said Lindberg. “Drivers can expect some single lane closures overnight as our trucks move equipment from the site.”

In December 2007, record-setting rain damaged sections of a 320-foot-long culvert 45 feet underneath I-405. The collapse created a sinkhole just 12 feet from the southbound shoulder of I-405. Crews stabilized the sinkhole and diverted the creek so they could repair the culvert.

For more information, visit the project Web page: www.wsdot.wa.gov/Projects/I405/RentonCulvertReplacement.

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