The stretch of Highway 1 where more than 4 million tons of dirt and rock barreled into the Pacific Ocean just north of the San Luis Obispo-Monterey county line looks more like an old-fashioned boom town these days — minus the buildings.
White Caltrans vans and large construction vehicles carrying giant boulders fill roads zigzagging across the mound of earth, where you can still see a shadow of where the old highway — washed away in the May 20 Mud Creek Slide — used to be: a masonry wall peeking out from beneath the earth. Amidst it all, there are signs of progress where Caltrans plans to rebuild a quarter-mile stretch of road across the slide.
Caltrans announced this week it would construct the new road over the slide — which it called the biggest in the highway’s history — instead of around or through it, saying it was the quickest, least expensive option. On Thursday, Caltrans offered a tour of the site.
Work is well underway.
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Caltrans project manager Joe Erwin said about 15 core Caltrans workers and 20 support staff were working alongside dozens of contractors as of Thursday. Many of them are logging 13-hour days, arriving at 5:30 a.m. and departing at 6:30 p.m., according to Chris Martin of Associated Traffic Safety.
Big questions about the project, such as the ultimate cost and a target date for completion, haven’t been answered yet. Erwin said an earlier estimate that the highway would be closed at least a year hasn’t changed.
The process itself, however, is starting to come into focus.
One of the first steps is putting in place giant boulders — some of which were quarried in Cambria — to guard the edge of the newly created mini-peninsula, known as the “toe” of the slide, against the crashing surf. Caltrans resident engineer Rick Silva estimated 15,000 tons of boulders will be used.
Then, workers will build embankments to stabilize the main body of the slide at the north end. And, finally, the new road will be connected at its southern end to the existing highway.
“The north side is higher than the south side, so we’ve got to climb the slide as we go out over it,” Erwin said.
The new road won’t follow the course of the old highway exactly but “will be a little bit to the west, on land that didn’t exist before,” Erwin said.
Silva said the new road will probably be “a couple hundred feet” from the old highway, parts of which are buried under the slide, while other sections came crashing down the mountain along with other debris.
“The biggest challenge is overcoming the scale of it,” Erwin said. “There are so many different parts of it, and you can only focus on one thing at a time.”
Anatomy of a slide
The top of the slide, called the head scarp, is still moving.
Some dirt could still be seen cascading down the side of the mountain Thursday, kicking up dust. There’s considerably less movement there now than immediately following the slide, but there’s enough that Caltrans has set up a makeshift barrier of large cargo containers and concrete dividers halfway up the mountain to protect workers from falling rock.
The head scarp has two sections, with the northern sector considerably more active than the southern portion, said Martin, who’s using radar to monitor the mountain’s stability. If the soil moves more than seven-tenths of an inch over a 1,200-square-foot area, it’s Martin’s job to sound an alarm that would trigger an evacuation of workers in the area. That hasn’t happened yet, he said.
Below the head scarp is the main body, which is divided into the “head” and “toe.” There’s movement in the toe, as well — from the surf-caused erosion the boulders are meant to guard against. But the most important part of the slide, in terms of the new road, is the head of the main body. That’s where the new highway will be built.
On solid ground
Caltrans spent the past several weeks conducting geological tests on the main body to measure the slide’s stability.
Erwin said engineers drilled into the main body and used inclinometers, which measure slope and elevation. They looked at “how everything is moving, to see the differentials one day compared to another day, compared to another day,” Erwin said.
The results were encouraging.
“We’re surprised — pleasantly surprised — at how stable and compact the main body of the slide is,” he said.
The data obtained in the testing supported Caltrans’ ultimate decision to build a new road across the slide, a road that will be buttressed by a series of “embankments, berms, rocks, netting, culverts and other stabilizing material,” according to a Caltrans news release.
I’m interested in getting the road open as fast as we can, and they tell us this is the fastest approach, so I’m in favor of that.
Jim Ramey, general manager of Ragged Point Inn
Erwin said Caltrans considers four strategies in managing slide areas.
Two of these — clearing away debris shortly after it falls or (for instance) building a retaining wall — were rendered moot by the massive size of the slide.
A third option would have involved “cutting down the mountainside and pushing it into the ocean,” Erwin said, “until we got back to where the highway was before.”
This is what Caltrans did following the 1983 Pfeiffer Burns Slide — the biggest on the highway prior to Mud Creek. But the Coast Highway Management Plan, adopted 15 years later, discarded that approach to better preserve the coastline, he said.
That left Caltrans with the choice of either building a tunnel through the slide or building a new road over it.
“A tunnel can take decades to plan and accomplish,” Erwin said, “so that’s really not a viable option.”
Choosing to build a new road is just fine with Jim Ramey, general manager of Ragged Point Inn, who said business there has been “slower this year, for sure.”
Ragged Point is the last piece of civilization on Highway 1 before the closure point at Salmon Creek, 5 miles to the north. The Mud Creek Slide is just north of the closure, about 9 miles beyond the Monterey County line.
“It’s an impressive slide,” said Ramey, who accompanied Caltrans representatives and members of the media on Thursday’s tour. “You get a sense of how big it is when you get out here, and I do think they’ve made a very good choice on how to fix it.
“There’s so much land here that it would take forever to haul it all out. I’m interested in getting the road open as fast as we can, and they tell us this is the fastest approach, so I’m in favor of that.”
Brooke Burnham, vice president of marketing at Visit SLO CAL, echoed that sentiment by phone Thursday afternoon.
“It’s imperative that we get this open as quickly as possible,” she said. “If these businesses have to make it through a second peak season without that road, it will be really difficult.”
Burnham said her organization, the county’s nonprofit tourist marketing group, is working on a longterm plan “to orient people to the North Coast as a tourist destination.”
“We’re really encouraged by the progress being made, even just understanding what the plan is,” she said of rebuilding the road. “We need to know what we’re facing. Caltrans is working very hard on behalf of all of us, and we appreciate all they’re doing.”