Case Study of Slope Failures at Spilmans Island

This paper presents a case study for a dredge disposal site called Spilmans Island, located along the Houston-Galveston Ship Channel, east of Houston. Initially classified as a sand bar in the San Jacinto River, Spilmans Island evolved in recent years with the construction of perimeter levees to contain the flow of materials produced from dredging operations. These levees were often constructed on soft dredged sediments, and as the levees were raised, occasionally slope failures occurred. The objectives of this paper are to illustrate the importance of reconstructing the history of a site as a basis for geotechnical analyses, and to demonstrate the significance of keeping accurate records of past investigations, construction activities, slope failures and subsequent remedial measures. The results of the geotechnical investigation described in this paper offer a clear example of how such data can be used to provide reliable predictions on the stability conditions of raised levees.