Monitoring Suction Stress and Effective Stress in a Silty Sand Levee under Seasonal and Tidal Changes

Approximately 162 hectares of estuarine restored land in the state of Washington (WA) form one of the largest ecosystem restoration projects in the U. S. The project site is located about 64 km north of Seattle, WA. As part of this project, a 1,219-m-long setback levee was constructed using silty sand in 2014 to protect an industrial area behind it, while allowing for the site to be inundated with the Puget Sound water. This study aims to investigate the behavior of the variably saturated levee under field conditions over the past year and a half. The study area, levee section, and instrumentation plan are discussed. An array of field sensors consisting of tensiometers and soil moisture sensors installed at the southern end of levee are used to collect the data. Further, precipitation data is collected from a weather station at the site whereas tidal water fluctuations are monitored using a water level sensor. A near real-time data acquisition system is employed to collect and process the data from various sensors. The data collected from the sensors is used to monitor suction stress and effective state of the levee under various tidal loadings and climatic conditions.