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Sunday, December 16 , 2018, 10:23 am | Partly Cloudy 56º


Highway 1 Landslide in Big Sur a Massive Repair and Construction Challenge

With just such experience, John Madonna Construction of San Luis Obispo contracted to rebuild and restore scenic roadway


When you’re facing a “once in a lifetime” mudslide, it’s not a bad idea to hire a contractor who can call on two lifetimes’ worth of experience in road-building.

The mudslide is the enormous Mud Creek Slide on Highway 1 in Big Sur north of the San Luis Obispo-Monterey county line. The contractor is John Madonna, son of Alex Madonna — whose name is on both the famed Madonna Inn and the Alex Madonna Memorial Highway in San Luis Obispo.

The elder Madonna and his company moved tons of earth, laid down countless miles of asphalt and built hundreds of bridges on highways across California — including the last 12 miles of Interstate 5.

Now his son is carrying on in that tradition — and has been for quite a while. John Madonna Construction is contracted to rebuild and restore scenic Highway 1, both at Paul’s Slide and down the road at the even more massive slide at Mud Creek.

“This is a first,” Madonna said of the Mud Creek Slide. “The size of it’s historical.”

The highway has been reopened to one-way traffic at Paul’s Slide, 21 miles north of the Monterey County line, but the road at the Mud Creek Slide (where the highway was buried by an avalanche of dirt and rock) is expected to remain closed until late next summer.

That might seem like a long time, but Madonna said it would have taken even longer if contractors were still using the method they used on the Big Sur slide of 1983.

“It’s interesting to see how things have evolved,” he said. “Back in 1983 and ’84, they pushed 3 million cubic yards (of earth) into the ocean. It took nearly a year, and there were nearly 30 bulldozers pushing.”

There would be even more earth to move this time — 5 million cubic yards (or 8 million tons), Madonna said, so the process at Mud Creek would take even longer. But even if he wanted to, he couldn’t simply push all that earth into the ocean. The Highway 1 Big Sur Coast Highway Management Plan adopted in 1998, which seeks to preserve the coastline, wouldn’t allow it.

“We’re trying to work with Mother Nature,” Madonna said.

Paul’s Slide

That’s been a tricky proposition at Paul’s Slide, where 2 million cubic yards of material came rumbling down the hill.

Madonna said he originally planned to remove 161,000 cubic yards, but then an additional 300,000 cubic yards rushed down the mountain, so that had to be taken away, as well.

“We didn’t push it into the ocean,” he explained. “We filled along the edge of Highway 1 and made an embankment.”

John Madonna of John Madonna Construction, which is removing the slide — a project that could take until late summer 2018. Click to view larger
John Madonna of John Madonna Construction, which is removing the slide — a project that could take until late summer 2018. (Joe Johnston / San Luis Obispo Tribune photo)

It wasn’t cheap.

This approach, he said, was “more than double and, quite frankly, probably triple the cost” of pushing all 2 million cubic yards down the hill and into the Pacific. But it not only complied with the management plan, it also helped prevent further slide activity at the New Camaldoli Hermitage, just to the north.

(Part of the slide is actually on hermitage property, according to its website, and a portion of its 2-mile entry has already been badly damaged: “At one point, as someone described it, it was like driving up a one-lane stairway.”)

Although the highway at Paul’s Slide is open, it’s just a single lane. Flaggers have been directing alternating one-way traffic there 24 hours a day, but Caltrans is replacing them with a stoplight. Madonna expects repaving and reopening the two-lane roadway there to be a long-term project — possibly as much as another year — in part because the slide is still active.

“At Paul’s Slide, until it stabilizes, there will be no reason to pave it,” he said.

“It could be done in six months,” he said, “but I don’t think they’re going to pave it for a year.”

Mud Creek

The situation at Mud Creek, nine miles north of the Monterey County line, is even more complicated.

“At Mud Creek, it’s a different feeling because nobody really knows when the final resolution will be,” Madonna said.

The slide brought down “8 million tons in five minutes” May 20, he said.

The material that came down the mountain consists of what Madonna called “Franciscan mélange,” a kind of terrain found in the Coast Ranges and San Francisco Peninsula that he described as “pretty granular” and “a mess of different kinds of rocks.”

And, as at Paul’s Slide, the mountain is still moving at the area of the slide called the head scarp — the area of the slide that’s above the highway ... or where the highway used to be.

Half of those 5 million cubic yards that rumbled down the mountain in May are sitting directly on top of the old highway, Madonna said, which helps explain why digging down to the old road isn’t a viable option. Caltrans has opted instead to build an entirely new road — Madonna said it will be 2,000 feet of asphalt — over the top of the body of the slide instead.

Although the head scarp is still moving, the main section is “a pretty stable body of fill,” Madonna said. But it’s important to keep an eye on the head scarp, because it’s hard to know how much more material might come down.

He said a wet start to the current winter could actually help by pushing the remaining loose earth down the mountain more quickly.

“If we had really good heavy, early rains, it would help toward the final resolution for Mud Creek,” Madonna said.

Meanwhile, Madonna’s crews are hard at work shoring up the peninsula that formed when all that earth tumbled into the ocean. Huge boulders are being piled along the newly formed coastline. The goal is to fortify it against erosion, which already has begun to occur.

A bulldozer works at the Mud Creek site in August. Click to view larger
A bulldozer works at the Mud Creek site in August. (Stephen H. Provost / San Luis Obispo Tribune photo)

“We’ve lost 100 to 150 feet of where that peninsula started, so it’s retracted,” Madonna said. “That’s why we’re putting that rock buttress in, so we can maintain that highway above it.”

Madonna has modern tools at his disposal, such as radar that shows how and where the earth is moving on the two slides. He receives two 10-page reports at 5 a.m. each day with maps, graphs and charts that show how the earth is moving in various places on the slide and even, he said, the movement of “individual stones that are up on the mountainside.”

“We’re really just taking the mountain’s pulse,” he said.

He’s also got lots of human help, including about 20 people at Mud Creek and five more at Paul’s Slide. Some even worked on the 1983 Big Sur slide that blocked Highway 1 for a year.

“We’ve got plenty of people who have been in this business a long time,” he said. “Mark Amos is my superintendent, and we went to high school together (at San Luis Obispo High School in the mid-1970s). He’s a very tenacious and competent superintendent. I think he’s been a real key to this entire process.”

In 2016, Madonna and Amos worked on the $9.5 million Elephant Trunk retaining wall, about a mile north of Ragged Point that was designed to prevent rockslides on the ocean side of Highway 1. By contrast, the cost of the Mud Creek project is estimated at $40 million.

The Elephant Trunk work put Madonna’s company first in line for the current project, he said.

If the job is immense, the slide itself is just as awe-inspiring. Photos from the air show the scope of the event.

“It’s an awesome sight,” Madonna said. “It’s once in a lifetime to be able to work on a project that’s this monumental, this significant.”

— Stephen H. Provost is a reporter for the San Luis Obispo Tribune. This story is republished with permission. Follow the San Luis Obispo Tribune on Twitter: @SLOTribune.

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