Tunnel Business Magazine

OCT 2018

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TUNNELINGONLINE.COM 2 0 TBM: TUNNEL BUSINESS MAGAZINE // OCTOBER 2018 Subsurface Conditions and Design Adequacy Risk Allocation in Design Build: n c n s Achieving effective and balanced risk allocation in design-build ("DB") subsur- face projects has proven to be a challeng- ing process and objective, as well as a controversial subject. Some have pointed to overly aggressive owner procurement practices and contractual terms as rea- sons for that experience. Others have pointed to overly aggressive design-build- er pricing and inadequate contingency. The analysis and explanation, however, are more profound and complicated. The superficially simple DB characteristic of single-point responsibility does not auto- matically and necessarily produce or con- verge into risk allocation simplicity. To date, there has been significantly less examination of other more intricate technical and contractual factors that ac- count for the challenges and complexi- ties in achieving effective and balanced risk allocation in DB subsurface projects. These factors involve the dynamics, in- teractions and interdependencies ("DII Factors") between subsurface conditions and design adequacy risks, and risk allo- cation in those respects. Consider the following issues that de- rive from the DII Factors: • How does (and should) knowledge (data and evaluations) produced by subsurface investigations inform and guide the development of a project's final design approach? • How are interfaces and interde- pendencies between anticipated subsurface conditions and the spe- cific final design approach, and the compatibility and suitability of each relative to the other, evaluated and correlated during the design devel- opment process? • Can the specific final design approach be reasonably constructed in the par- ticular subsurface conditions? • Can materially different subsurface conditions encountered during con- struction result in the need to revise that design, or to consider and imple- ment an alternative design approach? • If, based upon encountered subsur- face conditions, the final design ap- proach needs to be revised or an al- ternative design approach developed, who should bear the cost and time impacts of those design variations? • Who should bear the risk of final design deficiencies attributed to an inadequate scope of subsurface in- vestigation or unreasonable evalua- tions or interpretations of available subsurface data? These are but a few of the basic issues, the analyses of which demonstrate the critical importance of the impact and in- fluence of the DII Factors in the assess- ment and allocation of subsurface condi- tions and design adequacy risks on major subsurface projects. sign- In design-bid-build ("DBB") projects, disputes arise between the owner and the constructor when subsurface con- ditions encountered during construc- tion materially vary from those condi- tions reasonably expected based on (a) owner-furnished subsurface data and evaluations and (b) the implications or expectations derived from the contract documents, as to the constructability, compatibility and suitability of the own- er-furnished final design in those condi- tions. Often, the owner's consulting engi- neer (directly or indirectly) is involved in such disputes. Even with a differing site condition ("DSC") contractual provision, reinforced and enhanced by a well-writ- ten Geotechnical Baseline Report ("GBR"), these disputes are often quite contentious and disruptive of project success. A study of many of those disputes would demonstrate that the variability of outcomes does (and should) depend upon the specific (factual, technical, contractual, legal and other) relevant factors. However, BY DAVID J. HATEM, PC F E AT U R E S T O R Y

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