The San Francisco Public Utilities Commission (SFPUC) awarded the Mountain Tunnel Improvements project (HH-1000R) to Michels Tunneling on Oct. 13 for $138,965,566. NTP is anticipated for Jan. 4, 2021.
The bid award was delayed through the summer months of 2020 by the development and implementation of new COVID-19 related construction safety regulations.
The project involves 11 miles of rehabilitation of the 10-ft diameter, concrete-lined, horseshoe tunnel, which was completed in 1925. Work includes concrete lining repairs, contact grouting, downstream valve control structure, large control valve installations, new tunnel adit, adit/portal improvements, tunnel siphon extension, water cut-off grouting, water discharge treatment, access roadway improvements, temporary staging area excavations and grading, the construction of a new 1,075-ft Adit Tunnel at Priest Reservoir to improve maintenance access, and environmental mitigations.
Most of the work will be 1,000 ft below ground surface and will be accessed via the downstream Priest Portal, and Adits 5/6 and 8/9 at intermediate locations along the alignment. Access will also be available 7 miles upstream via the 13.5-ft diameter unlined section of the tunnel from Early Intake. The project designer is McMillen Jacobs Associates (MJA) with AECOM as environmental consultant.