The USACE’s mission is to reinforce 42 miles of levee improvements to provide Natomas Basin at least 200-year flood protection.
Flood events in 1986 and 1997 pushed many Sacramento area levees to the brink of failure, including in Natomas, which has more than 100,000 residents and contains major transportation infrastructure such as the Sacramento International Airport, Interstate 5, Interstate 80, and Highway 99. Those two events prompted the US Army Corps of Engineers Sacramento District (USACE) and other agencies tasked with overseeing flood risk in northern California to work cooperatively to complete upgrades to the 42 miles of levee surrounding the Natomas Basin. The Sacramento Area Flood Control Agency (SAFCA) has already completed improvements to 18 miles of levee.
As part of this initiative, the USACE engaged AECOM to conduct a geotechnical investigation of 17 miles of levee along the east bank of Sacramento River at South Natomas Garden Highway. The project involved raising the levee and designing a seepage control measure.
AECOM’s duties included performing field exploratory borings; managing laboratory tests, including testing bulk samples provided by the USACE; and conducting various engineering analyses, including seepage and stability evaluation. Data collected from the field and results of the laboratory tests were compiled to develop geologic profiles for analyses. Engineering analyses included stability of the levees for static long- and short-term conditions, rapid drawdown, and seismic loading conditions; under-seepage and piping evaluation; and settlement estimates.
All geotechnical findings were summarized in geotechnical reports, along with design recommendations prepared by the AECOM team.