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Each year, CalGeo puts the spotlight on the best geotechnical projects in the state with its Outstanding Project Awards. A panel of peers selects the year’s finest work in several categories, providing winners with the opportunity to share details of the project and offer an opportunity for everyone to learn exciting, innovative approaches to challenging situations. This year, ENGEO received an Outstanding Project Award in the private-large category for Treasure Island Redevelopment Phase 1 in San Francisco, Calif. For over 80 years, Treasure Island has hosted and celebrated a variety of human achievements in architecture, engineering, art, and national and civic endeavors, the first of which was the island’s construction.
The island and the causeway that connects it to Yerba Buena Island were constructed in the late 1930s for the Golden Gate International Exposition after originally being conceived as an airport. In 1941, the U.S. Navy moved to Treasure Island as America prepared for World War II. By the time the war ended in 1945, aviation had changed dramatically, and the island never developed as an airport. The Navy maintained a base at Treasure Island until 1997, when the island was leased to the city of San Francisco.
Fast forward to the 21st century, and Treasure Island’s latest development plans include approximately 8,000 residential units, 250,000 square feet of retail space, 500 hotel rooms, adaptive reuse of historic buildings, a new intermodal transportation hub with a new ferry pier, a new marina, and approximately 300 acres of public parks and open space.
In 2005, ENGEO was brought on as the geotechnical engineer of record for the Treasure Island Redevelopment Project and, since then, has provided a wide range of services and utilized innovative approaches to address the unique characteristics of the island. Treasure Island features up to 180 feet of soil that poses a wide range of geologic hazards, including seismically induced liquefaction, long-term static consolidation settlements, and seismic instability of the shoreline and causeway that connects Treasure Island to Yerba Buena Island.
It was critically important for ENGEO to address the unique features of the island with a precise mitigation plan, including:
Optimization of liquefaction hazard and lateral deformation through robust field explorations, state-of-the-art laboratory analyses, and advanced numerical modeling
Mitigation of seismically induced liquefaction within the development footprint utilizing direct power compaction
Utilization of state-of-the-art non-ergodic seismic hazard analysis for ground-motion optimization for vertical developments
Implementation of 2- and 3-dimensional finite-element modeling to evaluate static and seismic soil-structure interaction
Installation of an extensive instrumentation program to monitor the performance of existing buildings potentially impacted by the geotechnical mitigation program
The resulting geotechnical mitigation program saved many millions of dollars and years of construction. Discover more about ENGEO’s work on the redevelopment of Treasure Island.