The city of 32,000 people at the foot of the San Mateo Bridge dates to 1962, when 18 million cubic yards of sand were dumped into the remnants of a tidal marsh along San Francisco Bay. It wouldn’t exist except for the levee around the edge that now is being replaced by a stronger and taller one — in part to keep out the higher tides anticipated with sea level rise.
The $90 million project began last October and extends 6.2 miles in all. It is being financed by residents who were warned that without a new levee they would be forced to buy expensive flood insurance. Until work is completed in 2023, the joggers and strollers who previously used the trail atop the levee are being steered to the sidewalk along the homes. A bike lane hugs the concrete barricades of the construction zone.
“I’m spending a lot more time in my parks than I did a few months ago,” admitted Sanjay Gehani, the mayor, one of many residents deprived of daily strolls with wide views of the bay. “But we’ll definitely be getting a better levee. It’s a big project with a big payoff.”
Whatever the payoff — including a wider levee-top path — the newly fortified wall will serve as a cautionary tale.
Foster City is one of several large developments built along the bay in the decades after World War II, when the region’s population was exploding and decision-makers had no compunction about pushing as far into the water as engineering technology would allow. Now, these settings face the reality that nature can only be defied for so long. That’s why the residents of the community have little choice but to build an emphatic wall supported by interlocking steel plates.
“Foster City shows what happens when there’s no wiggle room,” said David Lewis, executive director of the environmental group Save the Bay. “They’re buying themselves a few decades. We hope.”
The conversion of marshes and mud flats along the bay dates to the Gold Rush, when newcomers to San Francisco leveled sand dunes so they could extend the fast-growing city as much as 12 blocks into the bay.
Foster City took the casual defiance of nature to a new level.
The natural mosaic of rivulets and pickleweed gave way by 1900 to commercial oyster beds and then a dairy farm on “swampy grazing land,” in the words of one historical account. But the growth of San Francisco to the north and the emergence of Silicon Valley to the south signaled a much more urban future.
Enter T. Jack Foster and his sons, developers who purchased the 2,600-acre dairy farm in 1960, and one year later submitted a plan to San Mateo County to build a new community that could hold 35,000 residents. Construction crews followed not long afterward, eventually hauling in sand from shoals off San Bruno to elevate the huge site 8 feet above sea level.
The city’s early development brought such suburban staples as the garden apartments and single-family homes on Ocean Beach Boulevard. They’ve been joined since 2000 by boxy condominiums and glassy office buildings.
In 2014 something else was added. A ticking clock — an expensive one.
The Federal Emergency Management Agency notified Foster City that new studies showed the existing levee was neither strong enough nor high enough to resist a major storm and the waves it might generate. Unless it was rebuilt, FEMA would designate nearly the entire city as being in a revised floodplain.
The city drew up plans for a new levee that would meet FEMA’s criteria. But it didn’t account for sea level rise projections, which brought a warning from the Bay Conservation and Development Commission, a state agency that must approve any projects along the bay.
“Large shoreline projects ... must be resilient to a mid-century projection of sea level rise, including risk associated with storms,” the agency said in a 2017 letter. “The commission cannot approve a project that is not consistent with the policies of the San Francisco Bay Plan.”
The past
San Mateo County, 1894
San Francisco Bay
Mariners Point
Seal Slough
Belmont Slough
(FOSTER CITY)
REDWOOD
SHORES
The present
Foster City, after 1962
San Mateo
Bridge
San Francisco Bay
Seal Point
Park
Mariners
Point
Golf
course
Seal Slough
Belmont Slough
FOSTER CITY
FOSTER CITY BLVD.
Redwood
Shores
Lagoon
REDWOOD
SHORES
The future
with 48-inch sea level rise
New levee plan
Concrete
flood wall
Hybrid
sheet pile
Earthen levee
(no wall)
Mariners Point
Depth of flooding
FOSTER CITY
Leo J. Ryan Park
Shorebird
Park
Edgewater
Park
Sea Cloud
Park
Redwood
Shores
Lagoon
Taking the hint, Foster City added several feet to the levee’s design, lifting its peak above projected sea levels for the bay through at least 2050 and satisfying the commission’s rules.
The steel is thick enough to resist not only earthquakes and strong storms — and the pressure of the 100,000 cubic yards of new soil that will be packed in behind the interlocked plates — but to support an addition when and if there’s a need to go higher.
When the project went to local voters in 2018, capturing 80% of the vote, the chief selling point wasn’t the virtue of a proactive response to climate change. Instead, city leaders emphasized that while homeowners would need to pay an average of $272 annually to finance the bond, flood insurance rates would be at least $2,000 a year.
One year later, the bay commission signed off on the final design.
Another plus: Foster City’s inland channels of water — echoes of the slough that threaded through the long-gone marsh — will be connected to the bay so water can circulate more naturally.
“You all took the bull by the horns,” City Manager Peter Pirnejad told residents who tuned into an online town hall in late January, complimenting them on their 2018 vote. “This is a great opportunity to brag to your neighbors a bit. We’re the first west bay city to address sea level rise.”
Most people who live on or near Beach Park Boulevard seem resigned, not boastful.
“I knew it was coming, but I was surprised at first by how tall it was,” said James Wagner, who moved into his small house facing the levee 36 years ago. “It’s quite a change.”
At the same time, “It’s smart to be thinking ahead,” Wagner said. “Foster City is being proactive. The Army Corps of Engineers didn’t leave much choice.”
Sue Spiekerman, a 24-year resident who would walk her dog each day atop the levee, also has mixed feelings.
“I definitely don’t like losing access to the levee trail for two years,” she said. “But if it’s necessary in order to save our housing, it makes sense to do it now.”
Pirnejad conceded as much when leading visitors along the fenced-off levee where machines use vibration pressure to push the steel sheets into the soil.
“It’s not like the city chose to be the front-runner,” Pirnejad said. “This was forced on us.”
If the region could turn back the clock, Foster City might not exist. The runways of SFO might not reach into the bay. Bel Marin Keys might not be a canal-sliced cul-de-sac.
But for now and generations to come, their presence is a reality that must be defended. It is hard to imagine the economic disruption or political firestorms that would be caused by proposing to displace entire communities or one of the nation’s largest airports.
For more than a century, too many Bay Area power brokers saw the bay’s mud flats and marshes as voids to be filled. They had no interest in the ecological value of natural habitats. No idea that sea level rise might cloud the horizon.
Which means that places like Foster City have little option but to build higher walls. Ones cloaked by shrubs and trails, perhaps, but defensive barriers all the same.
“It’s not that we can’t combat nature with engineering. We can,” said David Lewis of Save the Bay. “But it’s a high cost. And with climate change, that cost will grow exponentially.”
June 18, 2021 at 07:00AM
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Can Foster City's new massive, 2-mile steel wall keep sea level rise at bay? - San Francisco Chronicle
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