Representative Projects: Dams & Levees :

Lake Orinda Dam, Orinda, California - Hultgren-Tillis Engineers performed a seismic evaluation of the existing dam in response to a request by the State of California Department of Water Resources Division of Safety of Dams (DSOD).  The initial dam was completed in 1928 and then raised 5 feet in 1935.  The dam is about 45 feet high with downstream slopes inclined at about 2:1 and upstream reservoir side slopes inclined at about 2.5:1.  The dam is a relatively homogenous embankment without an internal drain.  A concrete spillway is located in the left abutment.  The reservoir provides irrigation water for the golf course.  

Hultgren – Tillis Engineers assessed the margin of safety during a selected seismic event and estimated embankment deformation.  The initial study indicated that improvements were needed for the dam.  Hultgren – Tillis Engineers developed alternatives to improve the seismic safety of the dam.  Alternatives under consideration to improve the performance of the dam in an earthquake include providing a toe berm at the base of the downstream slope, deep soil mixing below the toe berm to strengthen the foundation soils and installing internal drainage.