Tunnel-contract papers noted the pipe Bertha later hit

The Seattle TimesJanuary 26, 2014 

This photo from Jan. 7, 2014 shows objects encountered by the State Route 99 tunneling machine.

WSDOT

The steel pipe that tunnel machine Bertha struck in December wasn’t just some scrap that a contractor forgot to remove in 2002 — but a crucial piece of equipment that engineers reused as recently as 2010, to learn how groundwater and construction affect each other.

The findings were shared with construction companies during the homestretch of the bidding competition to drill the world’s widest single-bore tunnel.

The pipe’s location and purpose are described in two documents the state Department of Transportation (DOT) provided to potential bidders, including Seattle Tunnel Partners (STP), which won the $1.44 billion Highway 99 tunnel contract.

Yet somehow, Bertha hit the pipe Dec. 3. Workers removed a 55-foot section that had been pushed upward, and the machine advanced for three more days, until the cutting teeth stopped grabbing soil. Operators turned off the tunnel machine to avoid damaging it.

Read more...

The Olympian is pleased to provide this opportunity to share information, experiences and observations about what's in the news. Some of the comments may be reprinted elsewhere in the site or in the newspaper. We encourage lively, open debate on the issues of the day, and ask that you refrain from profanity, hate speech, personal comments and remarks that are off point. Thank you for taking the time to offer your thoughts.

Commenting FAQs | Terms of Service