Project Specifics

The Lower San Joaquin River Phase C-2 project is part of a larger flood-risk-management program to reduce flood risk in the North, Central, and South Stockton basins in California. Phase C-2 focuses on the Calaveras River Right Bank levee system and includes reaches totaling approximately 23,130 feet of levee between the San Joaquin River confluence and North El Dorado Street. The project advances levee improvements that meet United States Army Corps of Engineers (USACE) and non-federal sponsor design requirements while supporting long-term flood resilience for the Stockton community.

Geosyntec Scope of Services

As part of the Geosyntec–Gannett Fleming Joint Venture, Geosyntec is providing geotechnical design and analysis services for the Phase C-2 levee improvements. Geosyntec’s work includes evaluating subsurface information; developing reaches and critical cross sections; conducting seepage, stability, seismic, and erosion analyses; and preparing geotechnical basis of design reports at the 35%, 65%, 95%, and 100% design milestones. Additionally, Geosyntec is supporting the development of geotechnical construction plans, technical specifications, design documentation report (DDR) input, and Engineering Considerations and Instructions for Field Personnel (ECIFP).

A key element of Geosyntec’s role is supporting USACE’s risk-informed design process. USACE’s in-house risk cadre leads the formal risk assessment process. Geosyntec’s role is participating in the updated risk evaluation for the Phase C-2 improvements, providing technical input to Cost & Schedule Risk Assessments, and incorporating risk evaluation results into the geotechnical design. This includes helping evaluate how proposed improvements address risk drivers such as seepage, seismic performance, slope stability, and waterside erosion, and using the results to refine design approaches for each levee reach.

Geosyntec’s collaborative approach enables close coordination with USACE technical disciplines, including civil and H&H teams, to facilitate integration of the geotechnical design into the overall design. Our work includes erosion evaluations and analysis and review of civil design documents for consistency with geotechnical recommendations. We are also developing plans and specifications, as well as final geotechnical deliverables for construction and advertising-phase support.

Notable Accomplishments

Geosyntec’s key project contributions on this major federal flood-risk-reduction effort include the following

• Supporting risk-informed levee design for approximately 4.4 miles of Calaveras River Right Bank levees
• Translating USACE risk assessment outcomes into geotechnical design decisions and reach-specific improvement recommendations
• Providing geotechnical engineer-of-record services for Phase C-2 design deliverables, including Geotechnical Basis of Design reports, plans, specifications, and final stamped geotechnical products
• Advancing design in accordance with USACE and Department of Water Resources (DWR) criteria, including risk-informed design guidance, levee design standards, and applicable civil works program requirements.

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