Alameda Siphon No. 4 involves the construction of a new 66-inch diameter pipe that extends across Sunol Valley from the existing Coast Range Tunnel to the Irvington Tunnel.
Client:
San Francisco Public Utilties Commission
Location:
Sunol Valley, CA
The new pipe will include a connection to the existing pipeline exiting the east portal upstream of the existing connections for Alameda Siphon No. 2 and No. 3; new chemical feed points, crossings of the Calaveras Fault and the Alameda Creek, and cross-connections to the existing three siphons, and the Irvington Tunnel at the west portal.
AGS, as a joint venture partner, is responsible for the structural, civil, and geotechnical components of the project. Significant features include design of:
Facilities: underground valves; new tower structures; foundation structures; equipment support structures.
Roadway and Retaining Walls: realignment of Calaveras Road, redesign of Alameda East Portal Road intersection; street improvements and storm drainage facilities; retaining walls employing soil nail, soldier pile and lagging, interlocking blocks.
Geotechnical Fault Crossing/Creek Crossing: evaluation of subsurface conditions; assessments of fault rupture hazard, liquefaction potential, and landslide conditions; analysis of aquifer characteristics.
AEP Security Structure - Antiterrorism: design an arch and a dome steel structure to protect the portal from blast loads in a postulated explosive attack.
