Repairs to damage from winter storms continue on Highway 1 on the Big Sur coast. Caltrans officials released updates Tuesday on two major slides that occurred this winter.
The Mill Creek slide took place Jan. 14 at PM 18 in Monterey County. The repairs at Mill Creek are in their final stages according to Caltrans. The slope above the roadway has maintained its integrity during all recent rain events. Temporary concrete barriers still need to be installed along the southbound travel lane while permanent guardrail is being manufactured.
A small number of additional repairs still need to be made which require a period of dry weather before they can be accomplished. Approximately 30,000 cubic yards of material was removed during the repair at Mill Creek.
Paul’s Slide reactivated on Jan. 15 at PM 22 in Monterey County. For several years, Caltrans says they've managed debris falling at Paul’s Slide by creating a catchment area along the northbound shoulder. Concrete barriers and fencing were utilized as a protective barrier between the travel lanes and the catchment area.
Falling debris would gather in the catchment area behind the concrete barriers and be removed at a later time. The catchment area at Paul’s Slide filled with debris and was cleared several times between last November and this January.
Due to Paul’s Slide reactivation with major activity on Jan. 15., slide material overwhelmed the catchment area along the northbound shoulder. The slide pushed concrete barriers from the northbound shoulder into the center of the roadway. Since Paul’s Slide reactivated, there has been no meaningful protection which could be provided for travelers below the slide.
While the effects of the slide on the roadway are visible, the magnitude of the slide above the roadway is more difficult Caltrans says. Along an almost quarter mile of the mountain, the Jan. 15 slide displaced a massive amount of material resulting in a bulging new slide within the larger slide.
Caltrans officials say it is almost like slicing a piece of birthday cake, the repair strategy calls for a vertical cut to be made on the mountain which will sculpt the slope in a way that will permit it to regain stability.
This repair has to be made in top-down fashion both for the safety of the crews removing the slide material and because the toe of the slide is currently providing a resisting force against downward force of the slide material above it.
Crews have established an initial pathway to the top of the slide area and have begun to bring material down. This work has been slowed by recent rains.
Once the weather allows the repair work at Paul’s Slide to resume in earnest, a massive earthworks operation will continue to bring slide material and cut slope down onto the roadway below. This work will not allow for any travel through Paul’s Slide while repairs are being made. Material near the roadway at the toe of the slide cannot be cleared as it is providing a resisting force to the slide above. There is no meaningful protection to debris which continues to fall from the slope above which and will continue to do so during repairs.
The amount of material to be removed at Paul’s Slide is estimated to be on the order of 500,000 cubic yards. This is over 15 times more material than was removed at the Polar Star or Mill Creek slides according to Caltrans.
There is no estimated time for reopening Hwy 1 at Paul’s Slide. It may be in the range of several months. Crews will continue to work all daylight hours seven days a week to make these repairs.
The Polar Star Slide took place on Jan. 4, one mile south of Ragged Point in San Luis County. Caltrans says the slope above the roadway has remained stable and has not presented with any issues since the highway reopened in Feb. 11. The slope was cut back to reach a point of stability and approximately 30,000 cubic yards of slide material was removed during this repair.