Kenny/Obayashi Low Bidder for Columbus OARS Project

The City of Columbus, Department of Public Utilities opened bids for Phase 1 of the Olentangy-Scioto Intercepting Sewer Augmentation Relief Sewer (OARS), which includes 23,300 ft of 20-ft internal diameter tunneled sewer. A joint venture of Kenny/Obayashi was the lowest of three bidders at $264,506,000.

Other bidders were Jay Dee/Traylor Brothers/J.F. Shea with a bid of $290,499,392 and Kiewit/McNally at $306,956,100. Pending approval by City Council, notice to proceed is expected to be given in September.

Phase 1 also includes a 52-ft internal diameter pump station shaft (Shaft 1), a 42-ft internal diameter screen shaft (Shaft 2), and a 48-ft internal diameter shaft (Shaft 6) with an internal surge chamber and hydraulic drop pipe. The depth to tunnel invert ranges from approximately 130 ft to 185 ft. Depth to bedrock varies from 30 ft to 120 ft. The tunnel, which will collect combined sewer overflows through the downtown area, will be constructed through limestone bedrock containing Karst features. Groundwater pressure at the tunnel elevation is anticipated to vary and require a pressurized face tunnel boring machine.

Phase 2, which is expected to be advertised for bids in early 2011, will include off-line Shafts 3, 4 and 5. Both projects are being designed by DLZ Ohio and Jenny Engineering Corp.