Rancho Palos Verdes Takes First Big Step Towards Possibly Slowing Portuguese Bend Slide

Topline:

Crews in Rancho Palos Verdes have started drilling exploratory holes along the Portuguese Bend landslide as they try to figure out where water is concentrated in the hillside so that they can drain it and hopefully slow down the land's movement.

Why it matters : After two years of heavy rains, the Portuguese Bend landslide (and the Klondike slide next to it) are moving at about one foot per week — a catastrophic amount of slippage that’s threatening entire neighborhoods.

What happens next: Once they discover where the water is located, crews will install hydraugers to drain water from around the landslide. It’s unclear how long it will take before the slide’s movement is impacted. But it could be more than half a year.

What draining should do: It’s likely that layers of impermeable bentonite clay have created a sort of giant bath tub, keeping loads of water from draining out of the hillside. The significant weight is causing it to slip faster. There’s also a theory that there’s an artesian well, or water under pressure, pushing up on the toe of the slide.