Posted on December 11, 2018
Belvedere officials are taking their chances with a caving seawall, hoping it doesn’t collapse into the bay and give way to flooding, as they put off a costly stopgap and wait for specialty steel to arrive.
Workers placed giant sandbags at the base of the barrier, on Beach Road, last month to give it support in preparation for the first storms of the season. But the real fix is hinging on an order of steel that is made to withstand the corroding effects of salt water. The manufacturer with the best timeline won’t have the metal ready until next month, said Craig Middleton, Belvedere’s city manager.
Engineers who have been monitoring the drooping seawall on a twice-weekly basis say it hasn’t moved in months. But in a pinch, Middleton said, the city could buy standard steel to prop the wall up and then change it out when the specialty material arrives. He’s hoping to avoid that alternative, which would be more expensive than waiting — unless the wall collapses first.
If that happens, Middleton said, waves could erode the levee behind the seawall, which connects Belvedere Island to the Tiburon Peninsula and prevents the Belvedere Lagoon, and the 290 surrounding homes, from flooding.
“We may lose the sidewalk, have to close the road, and then we’d still have to do the other fix,” he said.
But the levee is tall enough to prevent nearby homes from flooding during most storms, he said, even without the seawall.
The Belvedere City Council declared a state of emergency for the community in October, shortly after engineers warned that the barrier was on the verge of collapsing.
City officials had known the wall was problematic since 2017, when an inspection revealed that portions of the concrete had crumbled and cracked. After the discovery, workers began monitoring the embankment, and determined that a portion of it is slowly sagging toward the water. That report sparked concern inside City Hall, which quickly escalated when engineers working on plans to fix the issue in September found that the foundation along the entire wall isn’t deep enough to prevent against erosion and could cause the barrier to cave in.
Ultimately, the entire seawall will need to be stabilized, but consultants say the most problematic section — directly across from Peninsula Road — needs to be propped up immediately.
The emergency declaration was an attempt to illustrate the gravity of the situation for state agencies that will have to sign off on construction permits. Middleton said he’s still awaiting approval from some officials, but he’s confident that piece of the puzzle won’t give him too much trouble.
He expects the final repair will be completed by early February.
Gay Harris, who lives in Belvedere, said she’s not worried about the delayed project and the threat of a collapsing seawall.
“I thought they’d have it fixed by now,” she said. “But if they’re waiting on materials, I understand that.”
Harris is more concerned with the bigger picture of flood protection in her community.
She attended a community forum Monday where city leaders briefed residents about forthcoming projects that are set to safeguard Belvedere from the effects of sea-level rise, which experts warn is an imminent threat to the area.
The Beach Road seawall repair is one piece of the larger initiative, which will include raising the city’s two levees. The projects are expected to cost between $11.3 million and $27.1 million, depending on which design options the City Council selects. Community members on Monday had an opportunity to weigh in.
“I think everyone’s more concerned about all this,” Harris said.
Source: MarinIJ
