Priest Lake Tunnel
The Priest Lake Project is currently under design by the
UEB. The conceptual design consists of a 2400 lf of 10 foot diameter tunnel and
three shafts. The shafts will be from 100 to 130 feet deep.The geology is
diorite and schist. The purpose of the tunnel system is to provide a method of
bypassing the existing Priest Reservoir located at the upper reaches of the
Hetch Hetchy water supply for the City of San Francisco. UCM is providing peer
review and input on the geotechnical design summary report in conjunction with
Dames and Moore for the Utilities Engineering Bureau. UCM will also provide
support during construction which is expected to begin in January 1999.
Mountain Tunnel Crew - Constructed in the 1920's the new
Bypass Tunnel will connect to this existing tunnel. Notice the timber
tunnel supports.
February 1998 - Looking downstream from the dam crest at the reservoir outfall.