Design Flexibility Cuts Costs

by Raymond J. Blunk, (M.ASCE), Waterworks Engr.; Engrg. Design Div., Los Angeles Dept. of Water & Power, Los Angeles, Calif.,

Serial Information: Civil Engineering—ASCE, 1985, Vol. 55, Issue 1, Pg. 57-59

Document Type: Feature article


The Los Angeles Water Department saved $5 million on a pipeline project by investigating the capabilities of pipe fabricators to furnish the pipe size required and by being open to alternate pipe sizes. Two reservoir reconstruction projects show that by making bidding more competitive the city obtained a lower project cost, and design changes not only brought savings but solved some difficult design problems. Consisting of reservoir bypass, inlet and outlet lines, the pipeline work at the Fairmont Reservoir  2 and the Lower Franklin Reservoir is part of a $20 million pipeline project to replace hydraulic fill dams in a seismic area. For Fairmont Reservoir  2 a new outlet line was sized for maximum hydraulic slope and power generation. The city engineers based optimal pipe size on pipeline cost plus the cost of lost power related to head loss. They questioned pipe fabricators to determine the availability of 132 in. pipe, and found that only one fabricator could supply what they decided was the optimal size pipe. Another firm felt they could be competitive if they could bid a 144 in. prestressedconcrete cylinder pipe. Still another firm wanted the option of supplying 132 or 144 in. ID welded steel pipe. The city included alternates to enable contractors to bid either 132 or 144 in. ID prestressed concrete cylinder pipe and 132 or 144 in ID or OD welded steel pipe. Even though greater design costs and more complicated bidding resulted, allowing these alternatives guaranteed competition between pipe companies. The city realized similar savings on the Lower Franklin Reservoir project.

Subject Headings: Pipelines | Reservoirs | Project management | Pipe sizes | Bids | Fabrication | Steel pipes | Spillways

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