Tunnel Construction Issues with San Francisco's New 44-In. Water Main
Abstract
The San Francisco Public Utilities Commission (SFPUC) needed to replace approximately 518 m (1,700 ft) of the existing 1,120-mm-diameter (44-in.-diameter) riveted steel pipe (RSP) water main installed in 1885 in the Bernal Heights District of San Francisco, California. About 366 m (1,200 ft) of the main was installed inside a brick-lined tunnel; 213 m (700 ft) of the main was installed under private property. The water main is part of the pipeline system that delivers water from San Francisco’s University Mound Reservoir to the downtown distribution system. The new 625-m-long (2,049-ft-long) steel main, which includes 311 m (1,020 ft) inside a new tunnel, is on a different alignment and built entirely under the public right-of-way. The old pipes were grouted and abandoned in place.
This paper addresses problems encountered during construction of the new 1,525-mm-diameter, 311-m-long (60-in.-diameter, 1,020-ft-long) bored tunnel and how the problems were successfully resolved.
Major issues discussed include:
- Rebidding to include both microtunneling and conventional tunneling methods
- Soft soil pockets in the Franciscan fragmented rock formation
- Groundwater infiltration
- Problems with boring machines
2009
International No-Dig Show Proceedings
Thinh Nguyen
San Francisco Public Utilities Commission
Glenn Boyce
Jacobs Associates, San Francisco, CA
Eugene Shu
San Francisco Public Utilities Commission
Kevin Barry
San Francisco Public Utilities Commission
