During construction, Alameda Dam experienced foundation deformations which continued at a reducing rate after construction was completed in 1995. The ongoing foundation deformation rates showed an increase in response during a reservoir surcharge event which occurred during the June 2011 flood. This raised concerns regarding the dam’s stability and the client commissioned a comprehensive detailed stability assessment of the dam which included 2D and 3D stability analyses, as well as 2D and 3D stress-deformation analyses. The work also included an evaluation of the potential impact of the ongoing foundation movements on the appurtenant structures. The structures associated with the dam include a gated chute spillway with a hydraulic jump stilling basin, and low level outlet with a horseshoe-shaped conduit.

The project is being carried out in five phases. Phase 1 involved an assessment of the dam’s stability to assist in developing near-term reservoir operating criteria for 2012. Phases 2 to 5 involve site investigations, assessment of the long term stability of the dam and assessment of long term deformations relative to performance of the dam, the spillway and the low level outlet.

Services

• Site inspection
• Instrument data review
• Geotechnical field investigation program
• Structures condition assessments
• Instrumentation and monitoring program
• Deformation and stability analysis of the dam and structures
• Assessment of remedial options for the dam and structures
• Project management