Ma­jor Hwy. 1 mud­slide ‘could hap­pen now’ as crews work in Big Sur

The Tribune (SLO) - - Local - BY KATHE TAN­NER

When the slip­pery slope above Big Sur’s Mud Creek slid cat­a­stroph­i­cally on May 20, 2017 — ul­ti­mately bury­ing a quar­ter mile of High­way 1 with up to 40 feet of mud, rocks and more — U.S. Ge­o­log­i­cal Ser­vices sci­en­tists al­ready had been track­ing the earth’s move­ment there for decades, ac­cord­ing to a re­cently pub­lished study.

What’s more, some of the USGS tech­nolo­gies that de­tected the earth move­ment as far back as 1967 also helped keep work­ers safe dur­ing the $54 mil­lion repairs to get the road­way re-opened — and the tech is con­tin­u­ing to track po­ten­tial land­slide prob­lems.

Be­cause Mud Creek, Paul’s Slide and other land­slide-prone ar­eas of High­way 1 be­tween Cam­bria and Carmel aren’t out of the woods yet, said John Madonna of John Madonna Con­struc­tion, which did most of the repairs.

Even if it doesn’t rain any more this sea­son.

Land­slides fre­quently hap­pen when it’s not rain­ing, he said. A ma­jor slide “could hap­pen now or in May,” as was the case in 2017. Madonna ex­plained that the dan­ger time is when wet soil starts to dry out, los­ing the sur­face ten­sion that keeps things in place.

“It’s like when you take some dry dirt in your hand. Pick it up, squeeze it and let it go. If the soil is to­tally dry, it will go through your fin­gers and fall out of your hand. If there’s some mois­ture in there, it will stay in your hand,” he said.

As his dad, Alex Madonna, told him, “With­out any mois­ture, there’s noth­ing to hold it to­gether. Even sand will make a ball if there’s some mois­ture in it.”

CON­STRUC­TION CONTINUES

John Madonna Con­struc­tion, Cal­trans and oth­ers are con­tin­u­ing to col­lab­o­rate and work on High­way 1, es­pe­cially in the Paul’s Slide sec­tion.

“That was the big slide be­fore Mud Creek,” Madonna said, but even af­ter the repairs were done, the “an­gle at Paul’s Slide was un­sus­tain­able.”

Now, he be­lieves “we’ve found the sweet spot” to in­crease sta­bil­ity of the steep banks above the road­way.

“I’m re­ally ex­cited about the suc­cess that I be­lieve Paul’s Slide is go­ing to be,” he said, “and we should be done with that work by the end of sum­mer.”

There’s still work be­ing done at Mud Creek, too. Mon­ster boul­ders are be­ing hauled up High­way 1 to bol­ster the base of the re­tain­ing wall there, Madonna said. He said they’re reeval­u­at­ing to see what else can be done in the next few months to in­crease sta­bil­ity and safety.

“A tremen­dous amount of en­ergy came down in Mud Creek,” he said. “We think there’s more up there. There are a few pockets that we’re kind of won­der­ing what they’re go­ing to do.”

With the work com­pleted last sum­mer, he said, “we did the foun­da­tion,” but the rest is up to Moth

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