Development of an Integrated Methodology for Assessing Integrity of Levees Protecting Fossil Gas Infrastructure

At the confluence of the Sacramento and San Joaquin rivers lies a complex system of over 1,100 miles of levees — longer than California's coastline. Many levees are a century old, surrounding hundreds of thousands of acres of land, and mostly below sea level. This area is a major hub of fossil gas and electricity infrastructure, containing significant fossil gas production and underground storage fields, and it is crossed by major electricity transmission lines and fossil gas pipelines.

Levees in the Sacramento-San Joaquin Delta were built as simple peat dikes resting on marsh soils and are therefore highly vulnerable to damage from floods, wave action, seepage, subsidence, burrowing animals, earthquakes, and sea level rise. The structural integrity of levees in the Sacramento-San Joaquin Delta (Delta) has for decades been a subject of investigations and continues to be a source of concern. This project identified areas of high risk to fossil gas infrastructure in the Delta and tested multiple geophysical methods for assessing levee integrity at several Delta sites. Methods include remote sensing and seismic surface wave surveying, electrical resistivity, ground penetrating radar, and electromagnetic surveying. Geotechnical models developed for assessing levee failure modes and characterizing variability along levees incorporate the geophysical and remote sensing data.