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Portland CSO tunnels score national recognition Sep 2011
Paula Wallis, TunnelTalk
It was decades in the making; it set aside traditional contracting methods in search of a better way; and it saw and early use of slurry TBM technology in the USA. Now it has gained national recognition as one of the top engineering projects in the country. Portland's Willamette River CSO Tunnel Program is one of five finalists for the 2012 Outstanding Civil Engineering Achievement (OCEA) Award announced this week by The American Society of Civil Engineers (ASCE).
East Side CSO Northbound tunnel

East Side CSO Northbound tunnel

"I'm proud of how we implemented the CSO tunnel program," said Dan Saltzman, the Portland City Commissioner in charge of Portland Bureau of Environmental Services. "The only way that this enormously complex program could be successful was through excellent management, and that is exactly what Environmental Services delivered," Saltzman said.
The Willamette River CSO Tunnel Program is a major element of Portland's 20-year program to control combined sewer overflows (CSOs) to the Willamette River and Columbia Slough. The work consisted of constructing tunnels on both sides of the Willamette River, several tunnel shafts and connecting pipelines, two pressure sewers and a large pump station.
Paul Gribbon, Program Manager for the Owner, credits an innovative contracting method developed specifically for the tunnel projects as instrumental in completing both the $293 million West Side Tunnel Project and the $426 million East Side Tunnel Project ahead of schedule and under budget.
Portland CSO tunnels project

Portland CSO tunnels project

"Most of my career was spent working with traditional contracting methods, where claims and dispute review boards were the norm," said Gribbon. "With a mandated completion date for both the west and the east side tunnels, and the size and complexity of the job, it became apparent early on that the project would be very difficult to deliver as a low-bid contract. There were just too many unknowns and we could not afford public fights with a contractor on a project worth hundreds of millions of dollars, so we just thought it best to look for an alternative contracting method."
What they came up with was a cost-reimbursement/fixed fee contract. The contractor was selected through a qualifications-based selection process and under contract prior to design completion. This three-way partnership among the Owner (City of Portland), Designer (Parsons Brinckerhoff) and Contractors (Impregilo/Healy JV for the West Side CSO tunnel and Kiewit-Bilfinger Berger JV for the East Side CSO Tunnel) resulted in a rapid response to construction challenges, quick on-site decisions, a number of cost savings, and no disputes.
Gribbon added: "With the low bid the contractor never really accepts the plans as theirs, the plans are always the Owner's. But in this situation we were all in it together."
Work is finishing on the 6 mile x 22ft diameter East Side CSO Tunnel, with substantial completion of the project expected next week. Bill Mariucci, Project Manager for the contractor called the experience a career highlight.
East Side CSO TBM above Port Center Shaft

East Side CSO TBM above Port Center Shaft

"When you develop a plan, execute a plan, and it all goes to plan, it sure feels good," said Mariucci. "Since 2007, we have hit all the goals we set. It is a great achievement for everybody who worked on the project. The pre-construction phase where we could be involved in the constructability review and risk analysis, and as a team come up with the right technical solutions to avoid any surprises later, was a real advantage."
Jim McDonald, Project Manager for the Impregilo/SA Healy JV that delivered the West Side CSO Tunnel and the Swan Island CSO Pump Station in 2006, said the alternative contracting method worked better than expected.
"It was a very successful project for us," said McDonald. "It is one that we can say we completed on the original time and budget even though we added quite a bit of work to the original scope. We would never hesitate to work for the City of Portland again. It did not have as many layers that some public agencies have and the Project Manager, Paul Gribbon, was very accessible. He had direct access to Owner decision makers and was himself a key decision maker."
Three Herrenknecht machines excavated the two tunnels working at depths ranging from 100ft to 150ft (30m to 46m). Both contractors say the machines were well suited to the ground conditions and performed well. Herrenknecht also supplied a slurry machine for a micro tunnel drive for a connector pipe on the East Side Tunnel contract. The 3,000ft (914m) drive broke the previous micro tunneling record of 1,300ft to 1,400ft (4ft to 4.2m).
  • Looking into Opera Shaft

    Looking into Opera shaft

  • Opera Shaft with frame for removing tunnel rail and utilities

    Opera Shaft with frame for removing tunnel rail and utilities

Mark Havekost of Jacob's Associates that holds the construction management contract for the project, liked the collaborative approach. "The spirit of alternative delivery methods, whatever the mechanism, is to try to instil some collaboration to solve problems," he said. "We have all learned a lot on these projects. It has been fantastic."
Hoover Dam Bypass Pat Tillman Memorial Bridge

Hoover Dam Bypass Pat Tillman Memorial Bridge

Both tunneling contracts also came in under budget. Gribbon said the West Side Tunnel Contract was about $15 million under budget, and the East Side Tunnel Contract is currently projecting about $50 million under its original $426 million budget. He attributed better-than-expected progress rates on the East Side Tunnel for the saving, along with some luck.
"Back in 2005, when we were originally estimating the job we put in $45 million for escalation over the six year term of the contract. But due to the nature of the economy it never really happened, so as an Owner, on the cost reimbursable element, we had the direct benefit of the fact that costs for steel, concrete, fuel and other supplies did not go up the way we thought they would."
The project may need a little more luck next March when the ASCE will announce the overall winner of its top prize in Outstanding Civil Engineering Achievement. The project is up against the Hoover Dam Bypass Pat Tillman Memorial Bridge, outside Las Vegas, Nevada.
Judging the odds Gribbon hedged his prediction saying "people love bridges. Sewers don't really fire the imagination."
Still this is one sewer that has broken new ground in US contracting practices and it just may be the one that captures the nation's top civil engineering prize.
References
Alternative contracting and delivery methods - TunnelTalk, Sep 2011
Portland CSO closing in on breakthrough - TunnelTalk, Sep 2009

           

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