San Ramon Canyon Storm Drain

Rancho Palos Verdes
L.H. Woods & Sons, Inc.


Geotechnical Engineering

Geocon Leaders

Gerry Kasman

The San Ramon Canyon drainage system poses ongoing threats to the City of Rancho Palos Verdes and the community below 25th street. Landslide-induced rock and soil deposits have been transported by heavy rainfall events down the canyon.

In order to mitigate flooding, the City is constructing a large diameter (54-inch) steel storm drain system to convey storm water from San Ramon Canyon to the beach, and it will be designed to handle existing upstream flows for a 100-year storm event. The project includes a new mid-canyon storm drain inlet structure and tunnel alignment that will gravity flow through the tunnel to a “cut and covered” section of the buried pipe and transition into a second tunnel to a new outlet structure at the base of the bluff. The project’s total storm drain alignment will measure approximately 4,200 lineal feet of 54-inch-diameter pipe from inlet to outlet.

Geocon installed geotechnical instrumentation during construction of the storm drain to monitor ground movement occurring at and below the ground surface. The installation included four slope inclinometers and four multi-point borehole extensometers. Upon completion of the construction, Geocon mobilized the necessary equipment to decommission the instruments in accordance with the project plans and specifications.

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