Implementation of Optimized Ground Improvement Techniques for a Prime Real Estate Location in Southern California

One of the most comprehensive ground improvement projects was designed and built for prime waterfront lots located in Southern California within a high-risk seismic area with extensive environmental restrictions. The site’s subsurface materials consist of an uncertified fill underlain by layers of alluvial deposits resting on the volcanic formation. Site investigations identified four geotechnical challenges: (1) potential of uncontrolled differential settlement due to uncertified fill; (2) liquefaction potential of the fill and alluvial deposits; (3) potential lateral spreading; and (4) potential consolidation settlement of cohesive soils under the planned building load. To meet the tight construction schedule and the stringent performance criteria, a combined ground improvement program, including wick drains, dynamic compaction (DC), surcharge, and soil mixing buttress walls along the shoreline, was developed to address all geotechnical hazards. Instrumentation and construction monitoring played a vital role in meeting the design specifications, including providing an improved understanding of strength, deformation, consolidation characteristics, and liquefaction potential of the foundation soils. This paper discusses the design, instrumentation program, and how performance monitoring was implemented to control construction processes and improve the geotechnical design.