East Side Big Pipe tunnel boring machine to come to the surface

The TBM boring Portland’s East Side Big Pipe is due to reach the surface for the first time since it was initially submerged in June 2007. The TBM, affectionately named ‘Rosie’, finished boring more than four miles from the Opera Shaft to the Port Center Way Shaft on Swan Island on October 30th, 2009.

The 6-mile long (9.6km), 22-foot (6.7m) diameter East Side Big Pipe is the largest construction project in Portland’s 20-year program to control combined sewer overflows (CSOs). The city will activate the tunnel in 2011 to control CSOs from the east side of the Willamette River.

On December 1, a 700-ton (635-tonne) crane will lift Rosie’s 460-ton (417-tonne) main section out of the 100-foot (30.5m) deep shaft. Rosie’s 70-ton (63.5-tonne) tail shield will be lifted out of the shaft a few days later. Self-propelled vehicles will carry the sections to a barge that will haul them back to the Opera Shaft the week of December 7.

Using popular microblogging site Twitter, Rosie the TBM recently told her fans: “I've been building this big pipe for more than two years now. It'll be nice to come up for some fresh air next month and take a break.”

You can follow the last stages of her journey at twitter.com/RosieTheTBM