Mile Rock Tunnel is a utility tunnel in San Francisco, in the U.S. state of California that was originally constructed as the storm sewer outfall draining the Sunset, West Mission, Richmond, and Ingleside districts.

Mile Rock Tunnel
Inspection party: August 26, 1915
Mile Rock Tunnel is located in San Francisco County
Mile Rock Tunnel
Mile Rock Tunnel is located in San Francisco Bay Area
Mile Rock Tunnel
Overview
Coordinates37°46′24″N 122°30′32″W / 37.773356°N 122.508984°W / 37.773356; -122.508984 (south portal)
StatusActive
Operation
Opened1915 (1915)
Charactersewer tunnel (currently used for storm drain overflow)
Technical
Length4,233 feet (1,290 m) long

History

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The Mile Rock Tunnel started construction in 1914 and was completed by 1915.[1] The contract was initially awarded to Edward Malley, but he stopped work after five months because of the high cost of insurance; R.C. Storrie and Company, who were responsible for other large tunneling projects including the Twin Peaks Tunnel, assumed responsibility for the work in January 1915.[1]

Mayor 'Sunny Jim' Rolph and other officials, including City Engineer M.M. O'Shaughnessy performed an inspection of the completed tunnel using a car on August 26, 1915. The tunnel was fitted with temporary structures and lighting to allow the car to enter without the threat of flooding from the outlet, but as it was not wide enough to allow the car to turn around, the return trip was conducted in reverse gear.[1]

Design

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The tunnel was constructed by a combination of cut-and-cover (through soil) and boring (through rock) methods.[1]

See also

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References

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  1. ^ a b c d Maniery, Mary L. (February 1995). Historic American Engineering Record: Mile Rock Tunnel (PDF) (Report). National Park Service, Western Region, Department of the Interior. Retrieved 27 July 2018.
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