The City of Portland, Oregon’s Bureau of Environmental Services (BES) has selected the Impregilo/SA Healy JV to work on construction of its estimated $260 million West Side Willamette River CSO Project. Designed to cut combined sewer overflows into the city’s Willamette River, the project incorporates 4 miles (6.4km) of 14ft (4.3m) i.d. soft ground tunnelling, several shafts of up to 150ft deep, a new pumping station, and more than 16,000ft of 36-84in connecting pipelines, a large part of which will be microtunneled.
Following selection at the end of 2001 Impregilo/SA Healy first entered a preconstruction services agreement to assist the project’s design team with issues such as selection, type and number of TBMs required to meet the project’s contract end date of April 1, 2006; cost analyzes; identification of potential cost savings; and assessment of sub-contracting requirements. The preconstruction agreement ends in May and BES intends to sign a cost reimbursable fixed fee contract with Impregilo/SA Healy in May with notice to proceed expected by June 2002.
Two Herrenknecht slurry TBMs (one new, one used) have been procured to work in conjunction with a one-pass bolted and gasketed precast concrete segmental lining through soft river silts, sands and cemented gravels some 120ft (36.5m) below city streets and up to 100ft (30m) below the water table. The project is to be in service by the court mandated deadline of Dec 1, 2006.
"The selection process was based on several criteria," explained Paul Gribbon, West Side Program Manager and Principal Engineer with BES. "These included the bidder’s technical approach to the job; a fixed fee covering management costs, overheads and profit for both the preconstruction agreement and the future construction contract; and its plan for procuring minority/women/and emerging small business subcontractors. The cost reimbursable construction contract will cover labor, equipment, materials and subcontractors’ contracts.”
The Impregilo/SA Healy proposal submitted in Nov 2001 was accepted against two other proposals submitted by the Kiewit/Kenny JV and the Traylor/Obayashi/JF Shea JV. The design team for the West Side project is a group led by Parsons Brinckerhoff with Carollo Engineers, CH2M Hill, MWH, Tetrotech/KCM and URS. For construction management BES will be assisted by Jacobs Associates.
