By Peter Kenyon, August 20, 2014
Design modifications to the shaft currently being excavated
to enable access to stricken TBM Bertha have pushed back its completion
by a month and eaten into the two months of ‘float’ time built into
Seattle Tunnel Partners’ initial (June) recovery plan.
Construction of the shaft was due to be completed under
the original schedule by the beginning of October, but this has now been
pushed back to the end of October or early November. The work is taking
longer than previously anticipated as a result of complications
surrounding installation of the exceptionally large interlocking piles
that are needed to make the shaft self-supporting and thereby enable the
TBM to break through. The total number of piles has increased by 11
from the original design, to 84 in total. Despite the delay, Chris Dixon
of STP told reporters at a press conference in Seattle on July 29 that
the latest delay will not impact on the planned resumption of the TBM
drive in March 2015.
In the TunnelTalk Podcast (Podcast 1, below)
Dixon details the works currently taking place and explains why changes
were needed to the shaft’s initial design.
At the same press conference Todd Trepanier of the Washington State Department of Transportation (WSDOT) told reporters that the latest delays have served to increase already existing concerns about the ability of its construction team to resume mining in March 2015, as stated in the original June 16 recovery plan (Podcast 2, below).
At the same press conference Todd Trepanier of the Washington State Department of Transportation (WSDOT) told reporters that the latest delays have served to increase already existing concerns about the ability of its construction team to resume mining in March 2015, as stated in the original June 16 recovery plan (Podcast 2, below).