What goes into clearing a landslide? On Highway 9, it’s a lot of hours, people and uncertainty

A massive landslide on Highway 9 between Upper and Lower Glen Arbor Road in the Ben Lomond area.
A massive landslide on Highway 9 between Upper and Lower Glen Arbor Road in the Ben Lomond area. Caltrans crews have been working around the clock to clear and repair the roadway for an expected March 4 reopening date.
(Kevin Painchaud / Lookout Santa Cruz)

For nearly two months, dozens of Caltrans crew members have tirelessly worked in the Santa Cruz Mountains to reopen even one lane of Highway 9, which fell victim to a major landslide on New Year’s Eve. Recent rains caused more debris to crumble from the hillside, leaving much to do ahead of a hopeful March 4 reopening.

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Caltrans workers clad in their neon-orange vests and hard hats mill around a closed stretch of Highway 9 on a recent sunny Wednesday morning in the Santa Cruz Mountains. The crew is mostly moving equipment no longer needed and scoping out the work site. That constant evaluation is completely necessary, since even the engineers don’t know what the site might look like the next day.

On New Year’s Eve, the first of an intense series of atmospheric rivers slammed into the Central Coast, bringing piles of mud, rocks and trees tumbling down onto a half-mile section of Highway 9 in the Ben Lomond area and cutting off access to the main thoroughfare through the Santa Cruz Mountains.

Mud is packed onto the roadway. Temporary concrete barrier walls are stacked to one side. There are emergency cones, “road closed” signs and heavy machinery along the whole site. Nearly two months after the storms subsided, this stretch of Highway 9 still appears to be one large construction zone.

For almost two months, dozens of crew members from Caltrans, the agency responsible for maintaining state highways, have worked around the clock shoveling dirt, hauling debris and inspecting areas of damage in preparation for the highway’s planned reopening on March 4. The cleanup and repair effort is a massive undertaking, one agency officials estimate will cost between $2 and $4 million.

road closed signs
Highway 9 between Upper and Lower Glen Arbor Road in the Ben Lomond area has been closed since New Year’s Day because of a massive landslide.
(Kevin Painchaud / Lookout Santa Cruz)

Just clearing the road of the 5,000 cubic yards of debris — enough to fill an entire basketball court about 35 feet up — took about two weeks. It required workers to take on 12-hour shifts, with one team working during the day and another at night. Those teams had grueling schedules, often working six days a week. Caltrans emergency response engineer Jake Bradbury estimates that the agency had 50 workers on site at the peak of the slide-clearing efforts.

Getting the exorbitant amount of mud, rock, and broken trees off the road required a variety of heavy machinery, including excavators, loaders and massive hauling trucks to take all that mess to a ranch a few miles from the work site for temporary storage. Crews were not sure what they’ll do with the mountain of debris once the job is finished, but you can bet it’ll be repurposed somehow, either in other Caltrans projects or external landscaping endeavors.

“Contractors are always looking for soil, and as we’re doing these projects, we might need more soil, too,” said Bradbury.

Caltrans assistant engineer Cuong Pho was working the Highway 9 slide on this day, and had done so on and off in recent weeks. He was out of town on vacation when the initial slide occurred, but he was well aware of the forecast torrential downpours and what that meant for the saturated San Lorenzo Valley hills. He had seen a slide of similar magnitude on Highway 35, along the Santa Cruz-Santa Clara county border, but that one happened in a very remote part of the road. This one is an entirely different beast, said the 25-year Caltrans veteran.

“I’ve never dealt with a slide this big, this major, around here,” said Pho. “It’s still active, and it’s changing every single day now.”

Caltrans assistant engineer Cuong Pho
Assistant engineer Cuong Pho has been with Caltrans for 25 years. “I’ve never dealt with a slide this big, this major, around here,” he said. “It’s still active, and it’s changing every single day now.”
(Kevin Painchaud / Lookout Santa Cruz)

The intense effort to clear the roadway of debris is only the first step. With the March 4 reopening deadline fast approaching, this section of highway is still in disarray.

The lane of the highway directly beneath the treacherous 200-foot barren bluff — the part of the road most likely to be reopened first thanks to minor structural damage — is still caked with mud and littered with chunks of stone. Every 15 seconds or so, another thick stream of water, combined with sediment and crushed rock, oozes from the crater about halfway up the slope. It might as well be liquid rock, with its opaque gray appearance.

The garage of a private home teeters no more than 20 feet from the edge of the slope high above the hill, looking like the visual representation of anxiety. And this is after weeks of nearly around-the-clock labor.

The slide was so powerful that it destroyed the guardrail that separates motorists from the steep drop into the San Lorenzo River. It caused the road itself to crack and crumble under the immense weight of rock, mud and fallen trees.

The force of the slide took out the guardrail
Caltrans crews have been working continuously since the start of the year to clear a massive landslide that closed Highway 9 in the Ben Lomond area ahead of a planned March 4 reopening date. The force of the slide took out a guardrail and exposed a water main beneath the road.
(Kevin Painchaud / Lookout Santa Cruz)

The wet winter storms displaced so much ground from the surrounding hillsides that it even unearthed an ancient Apple Macintosh monitor, which the crew placed on top of the still-standing section of guardrail. “This is our work computer,” Pho said with a chuckle.

Workers still have to replace the guardrail. About 100 feet from the site of the Highway 9 slide, stacks of K-Rail barrier walls sit just adjacent to the road. They will eventually be used as a divider between the mountain road’s two lanes, once it’s safe to allow one-way traffic.

Along with visible damage to the pavement, a water main that runs underneath the road was totally exposed, leaving it vulnerable to any potential further slide. Since it is one of the primary water distribution systems for the San Lorenzo Valley, protecting that was of high priority.

“We had to fix that, because it could shut down water for a while, too,” said Pho. Crews used a material called slurry — a substance like cement, only softer — so the water main could be packed into the material and protected without putting too much pressure on the infrastructure.

The cleanup and repair work has been made even more challenging by the fact that the ground is still sliding and that even the slightest new weather system threatens to send more mud and rocks tumbling onto the roadway. Just a few weeks ago, a mild rainfall destabilized the area.

“We were analyzing the [New Year’s Eve slide] damage and what we needed to do to get that fixed,” said Bradbury. “Then more rain came through and that’s when that slide reactivated and more material came down.”

Bradbury said workers were forced to stop work at that point and are now trying to get as much water out of the slope as possible with the hopes that drier sediment will, finally, stabilize the hillside and put an end to the constant crumbling. How long that will take, though, is up in the air.

Spider excavators — a type of all-terrain machine with four independently operating legs allowing it to move across difficult landscapes in a similar fashion to the creepy-crawly arachnids — are stationed on the downward slope as they work to stabilize the hillside by digging out as much loose material from the crater as possible.

But on a recent Wednesday, the four-legged excavators were sitting idle on top of the slope, next to that precariously perched garage. Since the slide is still active, it was far too treacherous to chip away at the loose land.

“They’re tied back with a cable and anchored at the top,” said Pho. “But I still wouldn’t go in there.”

Blue Spider excavators the blue pieces of machinery) sit on top of the hillside, waiting for work to resume.
A garage teeters precariously atop a hillside above the Highway 9 closure. Nearby, spider excavators (the blue pieces of machinery) sit idle. The landslide is still too active to use the excavators safely.
(Kevin Painchaud / Lookout Santa Cruz)

Bradbury said despite the challenges and persistent hillside crumbling, he’s still optimistic Caltrans can hit its March 4 deadline.

“We haven’t officially changed our date for opening, and there’s definitely a possibility that we can have a lane open by the 4th,” said Bradbury. “Just because it reactivated doesn’t mean we’ve completely lost our schedule.”

Pho, however, is less sure.

“We’ve been dealing with not just rain that’s hit the hillside, but runoff from the top of the slope,” said Pho, pointing to a large plastic drainage pipe that spans the entire height of the hillside used to drain the runoff and dry out the soil to stop it from sliding. He estimates the pipe was drilled at least 150 feet deep into the slope, but the water keeps coming. “We don’t even know how much.”

The agency is still assessing its options for finishing the job in time. Engineers have thrown ideas around here and there, like installing a soil nail wall — an earth retention system used to provide stability by reinforcing the soil with a thin mortar and nails — or some other kind of buttress, but the team has yet to settle on a plan of attack.

“We keep trying to work out next steps and new ideas,” Bradbury said.

Those next steps, thankfully, were not affected by last week’s unusual snowfall and even more rain. But in a winter of uncertainty, the teams still at work will need to keep their options open.