Hamilton Wetland Restoration Project
Fugro conducted a geotechnical study including a field investigation, laboratory testing program, and engineering analyses for the reconstruction of the South Levee of the Hamilton Wetland Restoration Project.

This project is located at the former Hamilton Army Airfield, adjacent to San Pablo Bay and is characterized by a system of levees, a large tidal wetland area, a system of seasonal wetlands, internal berms, a breach in the outboard levee, and the lowering of the existing outboard levee. Dredged material was used to raise ground elevation and restore wetland habitat at the site of the former Hamilton Army Airfield.

The South Levee consists of two segments. The South-1 Levee is about 2,400 feet long and runs between and parallel to two existing drainage ditches. The drainage ditch on the wetland side will be covered once the dredged material is placed. The South-2 Levee is about 400 feet long and extends between the west end of South-1 Levee and a rock outcrop at Long Point.

An older, smaller levee parallels the outboard side of the new South Levee. The design called for the new South Levee to be constructed on the inboard side of the existing levee. The project required that the crest of the South Levee be constructed to Elevation 11.5 feet during the first phase of construction. The outboard toe of the new South Levee is located at approximately the outboard crest edge of the existing levee.

The scope of the geotechnical study included the following:

• Review of available site information, pertinent reports, and previous slope stability analyses;
  
• Field investigation specific to the failed section of the South Levee to characterize the subsurface conditions at this location;
  
• Laboratory testing of (1 selected soil samples retrieved from the exploratory borings to establish relevant geotechnical engineering properties for analyses and, (2 soil samples collected from potential sources of borrow material that may be needed for reconstruction of the South Levee;
  
• Geotechnical engineering analyses in order to develop conclusions and recommendations for reconstructing the failed section of the levee. Presenting earthwork and construction sequencing recommendations for the levee reconstruction; and
  
• Presenting recommendations for geotechnical instrumentation and monitoring of levee construction and during the life of the levee.