Professional Presentations:

Stability of Delta Levees; Tillis, R. Kevin; CALFED Bay-Delta Program Science Conference, Sacramento, California; October 3-5, 2000. -  Common stratigraphy of the delta levees consists of peat over sand.   Proper characterization of existing conditions of the soil and site on the delta islands is needed for assessing stability of the slope.  These include fill types and thicknesses, levee slopes, water levels in and below levees, and material properties of peat (strength and compressibility).  Typical existing conditions on delta islands are based on numerous borings, cone penetration tests and personal observation. Data is presented from the Delta Wetlands project and on reclamation district projects on Bacon Island, Bethel Island, Bouldin Island, Holland Tract, King Island, and Webb Tract.  The results from test fills on Bouldin Island and instrumented test sections on Webb Tract are presented. Typical cross-sections of delta levees are compared along with the results of slope stability analysis for the cross-sections.  Lists of factors that should be considered in design and analysis of these levees are presented along with the methods to improve levee stability.