ARE TEMPORARY FIXES OUR ONLY TOOLS AGAINST EROSION?

from Winter 2023

by Malibu Magazine

HOME OF THE MONTH 24824 PCH

The Big Rock Slope Restoration Project demonstrates how elusive a long-term plan for coastal erosion remains.

✎ written by Holly Bieler

 Photos by Julie

Wuellner

Erosion has left many parts of the PCH in Malibu unrecognizable, and none moreso than a small stretch of highway just east of Big Rock. The 200 feet of highway sits on one of the city’s most vulnerable areas for erosion, supported by a collapsing rock wall that was constructed more than 100 years ago. In 2016, high surf pummeled the area, shrinking the beach and crumbling so much of the rock wall it was at risk of collapsing. The erosion even reached PCH, destroying large swaths of the shoulder and washing chunks of pavement out to sea. As a result of the damage, a high-pressure gas pipeline was exposed, presenting “an imminent danger to the traveling public”, according to a Coastal Commission report.

Emergency workers were able to temporarily stabilize the rock wall with shotcrete, a kind of sprayable concrete. But the damage had struck a nerve. In a climate change vulnerability assessment released later that year, Caltrans District 7 identified the Big Rock corridor as highly vulnerable, and in an Adaptation Priorities Report released the next year, said repairing it was a first priority for the district. Local Caltrans officials began calling the area the most worrisome in their infrastructure portfolio in terms of erosion impact.

But five years later, finding a long term fix seems farther than ever before. Indeed the halting process of keeping PCH east of Big Rock from falling into the sea illustrates just how far we are from developing a permanent solution to our shrinking coastline.

By 2021, Caltrans had supposedly come up with a long-term fix for the Big Rock corridor. In their proposed Slope Restoration Project (SRP), they called for installing a new seawall under the highway, this time made with secant piles, a support system used in deep foundations that is drilled directly into bedrock and utilizes alternating piles as well as steel and concrete to create a water-tight surface. Total costs for the wall were pegged at $12.4 million.

The City was quick to support the SRP. Increased erosion on the Big Rock sea wall now meant that stretch of PCH was at risk of developing sinkholes, which overnight could trigger long-term closures of the highway, Malibu’s most essential roadway. In the worst case scenario, PCH could collapse while people were driving on it.

The secant pile wall, as Caltrans set out, would serve to ensure this didn’t happen. On the project’s website and brochure, the new wall was described as a “permanent solution”, a final fix to one of the area’s biggest headaches. Work was tentatively scheduled to begin in September of 2022, pending approval by the California Coastal Commission.

The following month, the Commission released their recommendation. The bottom line: the project was approved. The erosion was simply too bad, in too important a part of PCH, to let it sit in disrepair any longer.

“It has very limited, if any, alternate routes, in the event of damage; and it serves as an emergency evacuation route for adjacent communities,” the recommendation read.

But in order to break ground on the project, Caltrans would have to agree to a major, somewhat odd stipulation. Sometime within the next 50 years, the new secant pile wall would have to be torn down, and replaced with something better.

Indeed the Coastal Commission had found that the wall didn’t present a permanent solution to the roadway’s erosion at all. By their estimates, the project might hardly last more than a few decades. Caltrans could go ahead and build the new $12.4 million wall, the recommendation read. But within the next ten years, it would have to come up with a proposal that would actually fix the area permanently.

It’s an approach the Coastal Commission has recently adopted in other parts of Southern California which have been outsizely impacted by beach erosion. Over the last few years, the Commission has approved seawalls in San Luis Obispo and Sonoma County only with the special provision that the projects serve as temporary fixes, to be replaced once officials come up with a better solution.

What exactly that could look like is still unclear. Data seems to indicate that any form of armoring, the process of using physical structures to protect shorelines from erosion, can actually exacerbate erosion in the long-term. But the numbers get less definitive when it comes to finding a solution for halting, or even slowing, coastal erosion.

In its approval of the Big Rock project, the Coastal Commission didn’t present any ideas. But the 10 year span they gave Caltrans to develop a permanent fix suggests getting there will require a scale of time, money and innovation unparalleled in the city’s history.

But that’s a problem for another time. For now, officials are focused on the secant pile wall, which broke ground in September. MM

Hi All – Since the simple phrase “Thank You” doesn’t really cover it in this situation, allow me to elaborate a bit.

Hi All – Since the simple phrase “Thank You” doesn’t really cover it in this situation, me to elaborate a bit.

On [November] 2018, our family was rocked by the devastating fires in Malibu.

Three days later, Jaq and I drove Dad and Jadi to see the remains of their dream home. The first house they bought since getting married. It was probably one of the worst moments I can ever remember.

Dad and Jadi just held each other and cried – staring at a hole where thirty years of memories, family heirlooms, art work they had collected...a smoking, charred pile of destruction where their dream home used to be. The place where both of my children learned how to swim, ride a bike, have birthday parties and graduation celebrations.

Then, the always amazing Howard introduced them to all of you.

Ryan – to say you designed a masterpiece is literally an understatement. You listened to their ideas, and then proceeded to design a home that completely took our breath away yesterday.