Steel pipe deemed DSC in Seattle’s mega tunnel

According to a document released by the Washington State Department of Transportation (WSDOT) on May 8, the board found "WSDOT and its consultants were in an excellent position to identify the existence and depth of the steel casing.

"Furthermore, the timing was such that this potential obstacle could have been noted in the GBR before the project went out to bid in June 2010. Yet, WSDOT has declined any knowledge that steel casing existed within TW-2 prior to being encountered by the TBM."

WSDOT installed the 8in diameter steel pipe casing in a test hole in September of 2002. The 57ft (17.4m) diameter Hitachi Zosen TBM hit the casing approximately 870ft from the entry portal of the tunnel on December 3, 2013. In a letter dated December 12, 2013, contractor Seattle Tunnel Partners (STP), a joint venture of Dragados USA and Tutor Perini Corp, claimed entitlement to a Change Order under the following possible entitlements: WSDOT-Caused Delay, Differing Site Condition, Defective Specifications and Breach of Implied Warranty.

The recommendation issue last week only addresses the specific question of whether or not the 8in steel casing is a DSC under the contract. The hearing and subsequent recommendation did not deal with how the TBM was damaged or the costs associated with repairs.

The board said both the geotechnical baseline report and the environmental baseline report are "silent" relative to the specific tunnel obstruction encountered. The geotechnical and environmental data report prepared by WSDOT in 2010, indicated that observation wells had 2in-diameter PVC casings, which, as STP argues, would pose no substantial problem for the TBM.

"As it turned out, however, TW-2 had an 8in diameter steel casing, which caused a significant problem for the TBM."

The board also said that the contract requirements to investigate site conditions during STP's design and construction efforts were satisfied by the efforts expended in pursuing information through WSDOT and its consultant Shannon & Wilson, Inc.

STP's project manager, Chris Dixon, issued a statement: "Seattle Tunnel Partners has advised WSDOT that Seattle Tunnel Partners has accepted the recommendation and considers this issue to be resolved."

WSDOT's Todd Trepanier, the Alaskan Way Viaduct Replacement Program administrator, said: "WSDOT disagrees with the recommendation and does not consider this issue to be resolved. We are concerned with the reasoning used by the Dispute Review Board in reaching the recommendation. We are reviewing it and will continue to pursue the best interests of taxpayers as we determine the appropriate next steps."