|Seattle’s Big Bertha tunnel-boring machine||Hole down to retrieve Bertha|
Seattle’s “Big Dig” tunnel project shows another example of what a Delta Tunnel project will look like.
How does Seattle’s “Big Dig” compare to the planned Bay Delta Conservation Plan (BDCP) tunnels?
|Seattle’s Big Dig||Delta Tunnels|
|Number of Tunnels:||1||2|
|Diameter:||56 feet||40 feet|
|Depth below the ground:||120 feet down||150 feet down|
|Length of Project:||2 miles||30 miles|
|Number of vertical shafts:||0||10 – every 3 miles|
|Type of soil:||soft landfill||soft, alluvial soils|
After the first 3 weeks of the beginning of boring the Seattle tunnel in 2013, they were already 2 weeks behind schedule. Currently the projected 14 month project which was planned to complete December 2014 is now projected to take until August 2016 or later (almost 3 times as long as original projections). They’ve only tunneled 1,000 feet of the 2 miles/9,200 feet (our tunnels are 30 miles long) and have already used 70 percent of the estimated total cost (do I hear huge overruns?) Seattle’s “Big Dig” is only 2 miles long yet the tunnel-boring machine has been stuck underneath Seattle for more than a year. The machine is stuck in soft ground which used to be underwater (sound like Delta ground?) Now they are having to dig a huge hole down to haul the behemoth tunneling machine out to repair it. The huge hole caused them to have to dewater surrounding ground water and is causing nearby buildings to sink and crack. What a mess!
Why isn’t this what we will be looking at in the Delta if the tunnel plan goes through? Huge delays, cost overruns and unforeseen damage surrounds Seattle’s “Big Dig” and it’s only 2 miles long versus the Delta tunnel 30 mile, dual tunnel project.
Going “under the Delta” sounded so much less pervasive and more environmentally correct than a peripheral canal. Easier to “market” and “sell” to the general populace. But it is what it is – a huge construction project through the heart of sensitive Delta wetlands and rich farmlands that will do endless amounts of economic and environmental damage to Northern California.