Installing Pipelines with Microtunneling while Successfully Avoiding Claims—A Case History Illustrating the Value of Using Alternative Contracting Methods
by Brad Moore, P.E., (Kennedy/Jenks Consultants, Portland, OR. E-mail: BradMoore@KennedyJenks.com), Kimberlie Staheli, Ph.D., P.E., (Staheli Trenchless Consultants, Inc, Seattle, WA. E-mail: kim@stahelitrenchless.com), Bob Jossis, P.E., (Robert G. Jossis Consulting, Portland, OR. E-mail: rjossis@wildblue.net), and H. Scott Clement, P.E., (Portland Bureau of Environmental Services, Portland, OR. E-mail: Scott.Clement@portlandoregon.gov)
Section: Pipeline Planning and Design, pp. 1332-1341, (doi: http://dx.doi.org/10.1061/41187(420)122)
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| Document type: |
Conference Proceeding Paper |
| Part of: |
Pipelines 2011: A Sound Conduit for Sharing Solutions |
| Abstract: |
The City of Portland Bureau of Environmental Services has completed the design of the Balch Consolidation Conduit—the final segment of their West Side Combined Sewer Overflow (CSO) system, part of the City’s overall CSO program. This project includes 6,900 feet of 84-inch microtunneling in five drives and 950 feet of 54-inch microtunneling in a single drive. The project was originally envisioned to be a design-bid-build project; however as design progressed, the trenchless risks were identified and considered significant due to areas with extremely soft soils, landfill debris, and cobbles and boulders. As a result, the City chose to use an alternative contracting mechanism for project delivery that included choosing a contractor through a qualifications-based selection process at the 60% design level. From the 60% to 100% design completion level, the contractor participated in final design decisions, made suggestions for modifications to existing design features and provided input to refine cost parameters. This mechanism was previously coined "The Portland Method" on the West and East Side CSO projects. During construction of the third microtunnel segment, a large object (likely a large boulder) was encountered that caused the operator to lose control of the tunnel steering, resulting in major deviations in the tunnel alignment. On a conventional design-bid-build project, this would certainly have been considered a differing site condition that would have resulted in a significant change order and possible claims. However, due to the alternative contracting delivery method that was in place that included a collaborative engineering team, the Contractor, the City, and the Design Engineer were able to work together to mitigate the problems caused by the potential obstruction. Instead of abandoning the microtunnel drive and retrieving the machine in a rescue (or 911) shaft, all parties worked together to develop a compromised solution that could allow continued tunneling at a significant cost savings to the City. This included a number of creative and challenging microtunneling operations to install the pipe beyond the boulder while balancing the hydraulic requirements of the system. This paper will provide the details of the "boulder incident" and show how the Contractor, City and Engineer were able to successfully collaborate to solve a complex problem, demonstrating how alternative contracting delivery can eliminate the risk of claims on microtunneling projects. |
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