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7.1.E. - Page 32 <br /> modifications will be incorporated into the 100% Finalized Plans, Calculations and <br /> Specifications. All comments shall be either incorporated, or responded to if not <br /> incorporated. Consultant shall finalize all construction documents for bidding (i.e., plans <br /> and specifications) and shall finalize the Engineer's Cost Estimate. <br /> Task lb. Pipes at Shorebird Island and Bridge Parkway Bridges <br /> There is a 8-inch diameter water pipe that is supported on the existing (c. 1981-vintage) <br /> Shorebird Island bridge in Redwood Shores. Based on preliminary review, the bridge is <br /> 3-span, a pile support structure, with decks having roller-pinned type supports; the pipe <br /> is steel, supported by railer-type supports and is supported for deadweight loads. The <br /> pipe goes through the pier caps though empty annulus, requiring miter bends in the pipe <br /> to accommodate actual annulus locations. Pipe girth joint connections are made using <br /> Dresser-type slip coupling units. <br /> There is concern the pipe may fail under seismic loads. This might happen due to <br /> inertial loading on the pipe; differential movement between the bridge decks / pier caps <br /> and the pipe; thrust forces; abutment movements. <br /> There is a 16-inch diameter water pipe that is supported on the existing Bridge Parkway <br /> bridge in Redwood Shores. Based on recent inspections, one of the pipe joints has <br /> failed. There is concern that seismic loads would aggravate the situation. <br /> Consultant will evaluate the pipes to allow them to perform after a large earthquake on <br /> either the nearby San Andreas or Hayward faults. Using ALA (2005) terminology, <br /> Consultant will consider the pipes as Category Ill (important) pipe, designed for seismic <br /> effects considered a 975-year return period motion. <br /> Approach - Consultant will inspect the pipes and bridges at the two sites. Consultant will <br /> then establish site-specific seismic ground motions, considering ground shaking (975- <br /> years) and potential for permanent ground deformations (settlements and lateral <br /> spreads). Consultant will use existing subsurface information for Redwood Shores <br /> (original Redwood Shores development data, plus local soils report by Cooper Clark, if <br /> available), supplemented with any extra subsurface information made available to us. <br /> Consultant will evaluate the combined existing bridge -- pipe system for thermal and <br /> seismic effects. Consultant will examine the stresses in the pipe; deformation at pipe <br /> joints along the bridge; and impacts to the pipe at either bridge abutment. Consultant <br /> will try to establish the likely cause(s) of the damaged water pipe joint on the Bridge <br /> Parkway bridge. Consultant will also assess the likely performance of the bridge, as it <br /> pertains to the performance of the pipes. Consultant will establish the adequacy of the <br /> as-is system (likely not); and also provide upgrade options, including: <br /> • Modify pipe supports on the bridge <br /> • Modify pipe (change of joints; etc.) on the bridge and approaches. For the 16" <br /> pipe on the Bridge Parkway bridge, Consultant will develop a repair strategy for <br /> the pipe that has already had a damaged joint. <br /> ATTYIAGR/2012.OD1/G&E ENGINEERING Page 15 of 3O <br /> RF1/•n111nIi7 <br />