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PROPOSAL TO (.'ITY (IF SANTA ,4 NA P,4GE 22 AMENDMENT TO BRIDGE RETROFIT CONTRACT SEISMIC RETROPTT XTRA TEG Y Preliminary seismic analysis will be performed. Seismic analysis will be based on the preliminary geotechnical design memo produced by the project geotechnical engineer. The analysis would include a 2-D push analysis of the bent(s), dynamic analysis based on the proposed ARS curve per SDC 1.2, and estimated foundation stiffness of the as-built structure. Foundation investigation will be conducted based on as-built information and available subsurface information from adjacent structure(s). No subsurface investigation will be conducted during the Seismic Retrofit Strategy Phase of this project. The analysis will dctcn~nine elastic seismic displacement of the existing structure. Alternative retrofit strategies will be developed based on the "as-built" model analysis. A minimum of two retrofit alternatives will be developed. Same sets of analyses will be performed for the "retrofitted" structure to indicate the effectiveness of the proposed retrofit strategy. Seismic Retrofit Strategy Report will be prepared that contains the material as required under I&P Guide 4-2. We will also prepare General Plan Estimates for all thc retrofit alternatives that have been studied during the Seismic Retrofit Strategy process, and will confirm any proposed retrofit that would involve foundation work following foundation recommendations contained in the Preliminary Foundation Report. The subsurface investigation will be performed, if required, after the approval of the seismic retrofit strategy. We will attend a seismic retrofit strategy meeting to be held at Caltrans Division of Structure's office in Sacramento. WKA will present the design, preliminary seismic design analysis and preliminary design of colurnns and foundations to the Caltmns engineers. Approval of one seismic retrofit strategy would signify the approval of the retrofit concept, and to continue toward the final PS&E phase of the bridge design effort. The project is assumed qualified for the Programmatic Exemptions for Seismic Retrofit projects, and no environmental document will be needed for the proposed retrofit construction. It is assumed that City will prepare all environmental document (including the PES form) in the preparation of the consultant scope of work. 2- GEOTECHNICAL INVESTIGATION Development of m~ effective seismic retrofit strategy would require the support from a geotechnical consultant. In addition, because of the potential for additional foundation work, them would also be need to conduct limited subsurface investigation to confirm the design of the new foundation system as part of the seismic retrofit strategy. Earth Mechanics Inc, the original geotechnical subconsultant on the seismic retrofit contract with the City of Santa Ana, will be providing the geotechnical services. The scope of their services is included in Appendix B herein. 3- UNCHECKED DETAILS SUBMITTAL The bridge design will have prepared in accordance ~vith the codes and standards of Caltrans. The following list summarizes the key design components of the structural improvements for the proposed bridge widening and reconstruction. 1. All plans and design calculations will be prepared in English Units. Page 4 of 22