DRB examines Bertha obstruction case 5 May 2015

Peter Kenyon, TunnelTalk
In Seattle, USA, the Dispute Review Board (DRB) has heard evidence regarding the Differing Site Conditions (DSC) claim by Seattle Tunnel Partners (STP) that an 8in steel well casing ultimately caused the breakdown of the 17.6m diameter Hitachi-Zosen TBM, resulting in months of project delays. In this special report Peter Kenyon examines extensive project correspondence between WSDOT and its design-build tunnel contractor that was disclosed to Tunneltalk following a Freedom of Information request.

It is nearly 18 months since TBM Bertha hit an underground obstruction during excavation of Ring 146 of the Alaskan Way replacement highway bored tunnel. In all that time project owner WSDOT and its design-build contractor team of Dragados and Tutor Perini (STP) have been unable to agree – after months, and hundreds of pages of correspondence between them – who should bear contractual responsibility for the steel well casing that STP alleges caused extensive damage to the TBM. The casing passed through the cutterhead opening and into the screw conveyor, possibly damaging the bearing seal assembly in the process, and bringing tunnel construction to a halt.

Damaged TBM Bertha in the recovery shaft
Damaged TBM Bertha in the recovery shaft

The breakdown has ultimately led to project delays estimated at six months beyond the contractual completion date – which will be subject to time penalties for the contractor of US$50,000 a day. This is in addition to the cost of excavating a 28ft x 80ft deep recovery shaft, the cost of mounting a specialist heavy lifting operation, and the cost of completing major repairs and improvements to the TBM itself – including fitting a new main bearing – all of which will run to an estimated £125 million according to documentation presented to the DRB.

According to project correspondence acquired by TunnelTalk, STP has based its DSC claim around the argument that the obstruction in question – an old test well known as TW-2 belonging to WSDOT, and dating back to 2002 – was wrongly identified in contractual documentation as being of 2in PVC rather than 8in steel-cased construction.

It further contends that after the TBM was finally stopped on 6 December 2013 – following the discovery of two 3ft long pieces of metal in the conveyor belt, and three days after first losing power – STP “was instructed not to mention the ‘steel casing’ at any of the [subsequent] media briefings”. STP claims it was told by WSDOT three days later (9 December 2013) that the metal discovered in the conveyor was from one of its old steel-cased test wells (TW-2), but questions the motives behind WSDOT’s subsequent decision to delay going public with this information until 4 January 2014.

55ft long x 8in steel well casing section removed from the surface after being struck by the TBM below
55ft long x 8in steel well casing section removed from the surface after being struck by the TBM below

In its Potential Change Order (PCO) 250 Position Paper, presented in evidence to the recent DRB hearing, STP says: “Because WSDOT was reluctant to admit any responsibility for the presence of this 8in diameter steel casing at TW-2, WSDOT took roughly a month to develop its public ‘talking points’ in order to satisfy the public that STP, not WSDOT, is responsible and liable for [its] presence [there].”

Briefly, STP contends that when WSDOT drafted the design-build contract it “chose to determine the existence of a DSC based on three Contract Documents – the Geotechnical Baseline Report (GBR), the Environmental Baseline Report (EBR) and the Geotechnical and Environmental Data Report (GEDR), which were prepared by Shannon & Wilson, a WSDOT consultant, in 2010 – rather than the whole universe of known or disclosed Request for Proposal (RFP) documents.”

It is claimed in STP’s DSC Proposal that in only one of the three Contract documents – the GEDR – is there any mention of TW-2; but that it is wrongly identified as a “2in observation well”; and, furthermore, that “the GEDR prepared by WSDOT in 2010 indicated that observation wells [generally speaking] had 2in PVC casings that would pose no substantial problem for the TBM.”

STP accepts WSDOT’s counter-argument that the true nature of the well casing – i.e. as of 8in diameter steel construction – is mentioned in the GEDR Supplement. However, it contends that the Supplement (which was prepared for the RFP stage) is “not part of the contractual portion of the GEDR and thus has no contractual significance.” In any case, argues STP, the only mention of TW-2 within this “non-contractual” documentation is barely a sentence long and buried so deep in a mountain of paperwork as to be almost invisible.

TW-2 crosses the tunnel alignment (Shannon & Wilson map)
TW-2 crosses the tunnel alignment (Shannon & Wilson map)

“The single and only indication of TW-2 to possibly be an 8in diameter steel casing in all of the RFP Documents is found in one sentence, by reference to another well, TW-1, in Appendix C: Pumping Test Results.

“WSDOT placed this indication of TW-2 as possibly 8in diameter steel well casing in a single sentence in a 74-page Appendix of a 130-page report that was one of 14 reports in the 15,263 pages in the ‘non contractual’ portion of the [24,904-page] GEDR.”

WSDOT, however, refutes STP’s claims in its own Proposal Statement to the DRB. The project owner claims that in order to prove the existence of a DSC, and under the terms of the contract, STP must prove “actual subsurface or latent physical conditions at the site that are substantially or materially different from the conditions identified in the GBR, the EBR and the GEDR.”

It also contests STP’s reading of the contract that only the actual GBR, EBR and GEDR – and not their various appendices and associated RFP documentation – are to be used to assist in providing relevant data about possible obstructions.

Street level view of TW-2
Street level view of TW-2
Well TW-1 (identical to TW-2) with cap removed, as pictured by Shannon & Wilson, May 2014
Well TW-1 (identical to TW-2) with cap removed, as pictured by Shannon & Wilson, May 2014

WSDOT says in its submission to the DRB that the top of the 110ft deep well, which was protected by a removable cap at street level, was “easily observable” from the surface and therefore could not be considered either latent or subsurface under the terms of reference of what was necessary to prove a DSC.

Furthermore, WSDOT claims that the Ninth Circuit Court of Appeals has established in the past that Reference Documents that may not actually form part of the contract documentation nevertheless provide important information to design-builders, of which they should take heed.

The relevant section of Umpqua River Navigation Co. v. Crescent City Harbour Disrict reads: “A contractor cannot call himself misled unless he has consulted the relevant Government information to which he is directed by the contract, specifications, and invitations to bid. As we read them, the decisions of the Supreme Court and of this court do not permit the contractor to rest content with the materials physically furnished to him; he must also refer to other materials which are available and about which he is told by the contract documents."

Exactly how the DRB has adjudicated on the matter will not be known until it releases its public report. However, the recommendations of the DRB are not binding on either party, and thus far both STP and WSDOT have failed to accept a number of verdicts passed down by the DRB – a fact commented upon negatively by the Expert Review Panel last month (April 2015). Furthermore, WSDOT hints in its submission that even if a DSC is proved, what has not yet been proved is that the steel casing was actually the cause of the damage to the TBM. Either way, the matter seems likely to end up in a Federal Court.

WSDOT spokeswoman Laura Newborn said: "Several days of hearings on PCO250 took place in March, but to be clear, the only issue on the table was whether or not TW-2 represented a Differing Site Condition. There was no consideration of anything beyond that one issue. There is no cause consideration or cost consideration in this step in the process. We just received the recommendation this week and it is currently under review. We plan to make it publicly available after it is reviewed internally."

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