Seattle Tunnel Partners begins backfilling TBM access pit

Seattle — According to an update on the Washington State Department of Transportation’s (WSDOT) website, “Seattle Tunnel Partners continues to prepare the SR 99 tunneling machine for mining. Crews have spent several weeks conducting a series of preliminary tests – including rotation of the cutterhead in the open air at the bottom of the 120-foot-deep pit that was built to access and repair the machine. Over the weekend, STP began filling in the access pit with sand and soil – the final step before they resume mining.

STP's most recent schedule shows the machine will be ready to resume mining in the pit on Dec. 23. WSDOT cannot verify the contractor's schedule.