Agmt12 G&E Engineering System Inc.

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modifications will be incorporated into the 100% Finalized Plans, Calculations and Specifications. All comments shall be either incorporated, or responded to if not incorporated. Consultant shall finalize all construction documents for bidding (i.e., plans and specifications) and shall finalize the Engineer's Cost Estimate. Task 1b. Pipes at Shorebird Island and Bridge Parkway Bridges There is a 8-inch diameter water pipe that is supported on the existing (c. 1981-vintage) Shorebird Island bridge in Redwood Shores. Based on preliminary review, the bridge is 3-span, a pile support structure, with decks having roller-pinned type supports; the pipe is steel, supported by roller-type supports and is supported for deadweight loads. The pipe goes through the pier caps though empty annulus, requiring miter bends in the pipe to accommodate actual annulus locations. Pipe girth joint connections are made using Dresser-type slip coupling units. There is concern the pipe may fail under seismic loads. This might happen due to inertial loading on the pipe; differential movement between the bridge decks / pier caps and the pipe; thrust forces; abutment movements. There is a 16-inch diameter water pipe that is supported on the existing Bridge Parkway bridge in Redwood Shores. Based on recent inspections, one of the pipe joints has failed. There is concern that seismic loads would aggravate the situation. Consultant will evaluate the pipes to allow them to perform after a large earthquake on either the nearby San Andreas or Hayward faults. Using ALA (2005) terminology, Consultant will consider the pipes as Category III (important) pipe, designed for seismic effects considered a 975-year return period motion. Approach - Consultant will inspect the pipes and bridges at the two sites. Consultant will then establish site-specific seismic ground motions, considering ground shaking (975- years) and potential for permanent ground deformations (settlements and lateral spreads). Consultant will use existing subsurface information for Redwood Shores (original Redwood Shores development data, plus local soils report by Cooper Clark, if available), supplemented with any extra subsurtace information made available to us. Consultant will evaluate the combined existing bridge — pipe system for thermal and seismic effects. Consultant will examine the stresses in the pipe; deformation at pipe joints along the bridge; and impacts to the pipe at either bridge abutment. Consultant will try to establish the likely cause(s) of the damaged water pipe joint on the Bridge Parkway bridge. Consultant will also assess the likely pertormance of the bridge, as it pertains to the pertormance of the pipes. Consultant will establish the adequacy of the as-is system (likely not); and also provide upgrade options, including: . Modify pipe supports on the bridge . Modify pipe (change ofjoints; etc.) on the bridge and approaches. For the 16" pipe on the Bridge Parkway bridge, Consultant will develop a repair strategy for the pipe that has already had a damaged joint. ATTY/AGR/2012.001/G&E ENGINEERING Page 75 of 30 REV:01/10/12