Professional Presentations:

Levee Seepage; Tillis, R. Kevin; CALFED Bay-Delta Program Science Conference, Sacramento, California; October 2006 -

Seepage through levees can cause internal erosion and piping, possibly leading to a levee breach.  Seepage is discussed in two categories: “high” seepage that occurs through the levee and may exit on the levee face, and “deep” seepage that occurs in permeable foundation materials beneath the levee, commonly sand. 

The author uses data obtained from his involvement on the reclamation district projects on Jersey Island, Bethel Island, Webb Tract, and Montezuma Wetlands.  Potential seepage paths are discussed, including layering of fills, animal burrows, man-made features such as pipes and buried roadways, and trees and root systems.  The point source of seepage can be effectively controlled with cutoff trenches or sheetpiles.  Potential solutions to control risk of piping are described, including wider levees, seepage berms, vertical barriers, or internal drains.