Representative Projects: Dams & Levees :

Delta Wetlands Project, Sacramento - San Joaquin River Delta, Contra Costa and San Joaquin Counties, California -

The project consists of four Delta islands that have interior ground surface elevation approximately 15 to 20 feet below sea level.  The islands and their levees are underlain with peat.  Two of these islands, Bacon Island and Webb Tract, will be converted into water storage reservoirs.  Approximately forty miles of perimeter levees will be strengthened. 

Mr. Hultgren and Mr. Tillis undertook investigations of levee subsurface materials using a series for borings and cone penetration tests.  Stability analyses were conducted for a wide range of loading conditions, including flood and seismic events.  The project involved numerous special studies and evaluations including groundwater impacts that filling an island reservoir would have on adjacent neighboring islands.  Mr. Hultgren and Mr. Tillis designed a four mile long dam across the interior of Bouldin Island for an earlier phase of the project.  To assist in their assessment of rate of loading and magnitude of settlement, they designed and instrumented a full scale dam embankment section and monitored its performance for four years.