SFPUC New Irvington Tunnel
Location: Sunol Valley, CA
Project Contractor: San Francisco Public Utilities Commission (SFPUC)
Client: Southland Contracting / Tutor Perini, JV
Project Date: 2015
Description: The New Irvington Tunnel was constructed to provide a seismically-designed tunnel to deliver water from the Hetch-Hetchy Aquaduct in Fremont, California to 2.6 million customers across the state. The new tunnel is 3.5-miles-long, with diameters of 8.5 to 10.5 ft, and is between 30 to 700 ft below existing ground surface.
Construction excavation utilized conventional mining methods, including road header excavation and controlled detonation. Work also included a 120-foot deep temporary shaft at Vargas Road, two portals, a temporary ventilation shaft, an overflow shaft and other incidental work. Extensive dewatering and tunnel reinforcement were used for groundwater inflows and unstable ground along the tunnel alignment. More than 7.8 million pounds of cement grout was injected into the tunnel for groundwater infiltration control.
Municon prepared the Noise and Vibration Control Plan for the project, as well as the Geotechnical Instrumentation Plan and Submittal. Prior to construction, Municon provided a pre-construction photo and video documentation survey, which was repeated at the end of construction.
Municon provided the client with a sound barrier design, and during construction, provided sound monitoring with data logged sound level meters. An average of six seismographs were employed on a given day to provide vibration monitoring. Automated direct SMS alerts were configured to notify the contractor if vibrations exceeded the project criteria.
Geotechnical instrumentation included 35 manually-read Inclinometer Sondex Casing Piezometers (ISCP), 4 data-logged and remotely-read Multi-Point Borehole Extensometers (MPBX), and 22 arrays of data-logged and remotely-read MEMS In-Place Inclinometers (IPI).
Municon implemented the remote reading and automatic upload of the data to our servers to provide our client with near real-time web-based data presentation and alerts. In addition, we delivered weekly and monthly construction reports.