Amendment No 4 Terraphase 07172025 Combined

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Amendment No. 4 to Consulting Services Agreement between City of San Leandro and Terraphase Engineering, Inc 7/17/25 for Treatment Wetland Design Services Page 9 of 11 attendance of the pre- bid conference and response to technical requests during conference planning performed by others. • Develop a more extensive Phase 2 cost estimate update than the currently contracted update. The current contracted Terraphase scope of work is limited to removing Stabilization Project line items from the 100% Design cost estimate and escalating existing estimate unit rates to 2025 values using estimating software. The requested additional scope of work includes outreach to material suppliers and subcontractors to provide a more detailed estimate of significant and higher-risk construction tasks, including the MABR system and treatment wetland subgrade liner. • As discussed with the City in May 2025, Terraphase will provide engineering and coordination support with the City and others to integrate the Phase 2 instrumentation and controls (I&C) system into the WPCP I&C system. This was identified as a potential schedule and cost risk to the City, as the currently approved Phase 2 design identifies MABR operational parameters and shows Phase 2 communications cables terminating at a junction box at the WPCP. The objective of the proposed I&C integration effort is to describe the Phase 2 system’s control strategy, how Phase 2 controls are integrated with the WPCP controls system, and how the WPCP controls system displays and controls the Phase 2 system. The deliverable for this effort is a technical memorandum that describes these parameters such that the City’s I&C engineer can design the required I&C infrastructure and WPCP I&C system modifications as needed. Terraphase will be subcontract engineering services from Presidio Systems, Inc. (PSI), and Fluence Corporation (Fluence) to provide I&C engineering support during delivery of this task. • As discussed with the City in May 2025, Terraphase will reevaluate and revise the design of the WPCP effluent tie-in valve. This revision may include potentially changing the valve type (e.g., changing from a gate valve to a butterfly valve), providing a make/model specification for the appropriate motorized actuator for the valve, design of structural valve supports, and potential revision of the specified valve vault to accommodate the confirmed valve, actuator and appurtenances. The objective of this additional design scope is to not scope detailed design of the tie-in valve as contractor design-build scope in the Phase 2 RFP. • As discussed with the City in May and June 2025, Terraphase will facilitate a constructability review of the Phase 2 subgrade liner system. This will include identifying and subcontracting a qualified liner installation contractor, providing Phase 2 project background information and design documents, coordinating with the constructability contractor during their review, and discussing findings with the City. This task does not include revision of Phase 2 project plans, specifications, or cost estimate to incorporate approved design changes identified during the constructability review; any resulting revisions to Phase 2 design documents will be scoped and proposed at City direction after completion of the constructability review. • Update and maintain the Phase 2 project schedule through Phase 2 procurement. Terraphase will prepare an initial Phase 2 schedule under the current Phase 2 design support task, but this schedule will be revised to add further task detail and updated task start dates as the Phase 2 construction planning, engineering, and procurement progresses. It is anticipated that this task will begin during construction of the Stabilization Project and continue through bidding and procurement of Phase 2, likely in Q1 of 2026. Docusign Envelope ID: 273A48E5-126B-49E9-B9E2-7FB9D28A1969