A robust seawall that is well designed and guaranteed to last at least 50 years is a must to protect the heart of Pacifica and the infrastructure that is vital to all Pacificans. To our north, the well-built O’Shaughnessy seawall, constructed in 1929 to protect western-most San Francisco, has remained structurally sound for nearly 100 years. Because it has withstood a century of fierce storms associated with California’s periodic bouts with El Niño, the O’Shaughnessy seawall stands as an excellent example of the type of seawall we should demand for Pacifica.
As described in a 2016 SFGate article, the O’Shaughnessy seawall “featured a curved, wavelike wall with bleachers that gave people a place to sit and helped break up the incoming surf. A wide sidewalk and small landscaped area sat about 25 feet above the beach, with the top few feet of the wall extending above the sidewalk, as it does today. … The seawall helped protect the highway and Golden Gate Park from sand and waves — that used to wash much farther inland.” That seawall has also provided ample access to the beach, a beach that has been growing.
Nothing lasts forever and the O’Shaughnessy seawall has exhibited some minor deterioration, but the fix was relatively easy. Steel rods (rebar) used to reinforce the concrete were rusting, causing chunks of wall to slough off. That problem is solved by applying an erosion-resistant epoxy coating to the rebar, then repatching the wall.
Still, the anti-seawall-managed-retreat forces have argued that seawalls have always failed and thus are not a good solution. But that logic is as foolish as arguing bridges often fail. Should we not build bridges? A 2016 bridge failure exemplifies the real problem. A “simple” partially constructed pedestrian foot bridge across a busy city street in Florida failed, killing six people, and injuring 10 others. “Faulty design (insufficient rebar for interface shear capacity), lack of redundancy, lack of peer review and oversight all contributed to failure.”
Don’t let Pacifica’s seawall design suffer a similar design fate.
The design of the bridge must be reviewed, and those reviews must be available for public discussion. Any attempt to economically compromise with the anti-seawall factions by simply accepting the lowest cost construction, will only result in a cheap design and future short-term failures. Pacificans should review the city’s seawall renderings on the city website, join the April 29 Zoom meeting, and/or email any and all concerns to citycouncil@ci.Pacifica.ca.us