A Different Kind of Bore
12:27 pm
Fri March 14, 2014

Bertha Rescue Plan On Hold While Archaeologists Check Soil For Sites

The plan to dig a shaft 12 stories deep to fix Bertha, the Seattle tunnel boring machine, has been put on hold while archaeologists make sure crews won’t dig through important historical sites. 

On Thursday, workers started boring approximately 60 holes, each about as wide as a grapefruit, and digging as deep as 40 feet down through layers of Seattle's floor, which, at the moment, is also Bertha's ceiling. 

“The earliest sites in the Puget Sound are around 10,000 years old,” said Steve Archer, cultural resources manager for the Washington State Department of Transportation. “We’re not anticipating that we hit anything that early, but that’s kind of the range that we’re looking at. So anything from 10,000 years to 1950 is stuff that we would evaluate for its historic potential.”

The archaeologists are consulting with federally recognized tribes in the area including Tulalip, Muckleshoot, Suquamish and Snoqualmie tribes. Archer says his team will take each cylinder of soil and split it in two. Opening the slices like a book, they'll scan the soil for changes in texture and color, and anything that might indicate human habitation, like bits of glass or wood.

In an earlier round of inspections this year, the group came across a piece of prehistoric cedar rope.

"We recognize that the tribes are concerned about that kind of material," said Archer. "So we talk to them and we save any artifacts like that that we find." 

Unfortunately, Archer says, the rope was found mixed with materials of other historic periods, instead of in the neat layers that archaeologists always hope for. Thanks to a scramble of dumped ship ballast, hill makeovers and tide flats, the soil layers below Seattle's waterfront are a bit of a mess. The chances of coming across an intact site are low.  

Under the National Historic Preservation Act, federally-funded construction projects are required to scope out the archaeological significance of the disturbed area. 

In 2004, WSDOT canceled the construction of a dock for building and repairing ships at Ediz Hook in Port Angeles after crews came across a burial site of the Lower Elwha Klallam Tribe.

Bertha, the world’s largest boring machine, ground to a halt in December while digging a tunnel to replace the aging Alaskan Way viaduct. Late last month, an official for the contractor boring the Seattle tunnel said a six-month delay in the stalled construction a “slightly optimistic” forecast.