River Islands is a 5,000-acre site proposed for 15,000 residential units, 500,000 square meters of commercial space, a town centre, retail, golf course, recreational and educational development. The project design includes the construction of interior lakes, associated water crossings, and four new bridges across the San Joaquin River and Paradise Cut. ENGEO is providing geotechnical design, environmental consultation, testing and observation, stormwater management, ground- and surface-water monitoring, and construction management services for the project.
Design of River Islands Phase I included additional subsurface explorations to sample, test, and evaluate the existing Federal Project levee and the foundation soils beneath proposed new levees. The River Islands levees were evaluated for stability (static and seismic), seepage (through and under), and settlement under anticipated hydraulic loading conditions for 100- and 200-year river stages.
The site was analyzed using a site-specific nonlinear site response analysis program that includes the ability to estimate both the development and redistribution and dissipation of excess pore pressures and the seismic settlement of both liquefying and non-liquefying soils. To benefit the project owners this refined analysis was used to avoid increased construction time and costs. This process also avoided adversely impacting the risk of damage due to earthquakes.
The levee design and construction aspects of the project included levee foundation soil improvement using Deep Dynamic Compaction (DDC) and removing and replacing unsuitable foundation soils. Development of the first phase of River Islands includes: constructing approximately 2.8 miles of new levee and rehabilitation of approximately 2.5 miles of the existing Federal Project levee.