Land movement in Rancho Palos Verdes has slowed from one foot to 2.7 inches a week

Land movement in the Portuguese Bend area of Rancho Palos Verdes has slowed from an unprecedented one foot a week to an average 2.7 inches as residents brace themselves for the winter rain season.

According to the latest staff report, the entire landslide complex is also now around 700 acres, up from 380 acres.

City officials attribute the slowdown to dry weather spells and the city’s dewatering efforts, which have resulted in the removal of around 75 million gallons of water from within the landslide area.

“ The good news is if it does rain we are now pretty well winterized as best we can be with this landslide and the resources that we have,” Mike Phipps, the city’s geologist told City Council members on Tuesday. “I'm kind of in wait and see mode with the weather and how that performs.”

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In August, city officials warned that the landslide was deeper and moving faster than previously thought. That slide, Phipps said, has stopped moving. 

”The movement that we are seeing is probably more likely the shallower Portuguese Bend slide, across a lot of the good portion of the area,” he said.

Despite the 11 active dewatering wells, Phipps warned “we've reached this steady state where we're kind of at capacity with the dewatering system that we have in place."

There is a need in the future, he added, for more wells with larger pumps that can remove more water.

How we got here

Above average rainfall over the past two winters have changed the topography of the area. In the Portuguese Bend Beach Club area, for example, land has bulged upward about six feet from the ocean, creating a new beach.

The unstable land has also caused indefinite power and gas shutoffs for more than 200 homes in Rancho Palos Verdes and the neighboring city of Rolling Hills. The damage has prompted some residents to move out, while others have installed generators and solar panels as they fight to stay.

The city prepares for the winter

In October, city leaders approved $4 million for temporary measures to slow down land movement during the upcoming winter season. Fissures in Altamira Canyon and Kelvin Canyon were filled with soil, as well as a bentonite seal to prevent water collecting and seeping into the ground.

More landslide damage

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Brian Feinzimer

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LAist

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But officials warn in the latest report to Rancho Palos Verdes City Council members that the budget approved will not be enough to complete temporary measures in Paintbrush and Ishibashi canyons. They say it's because some of the fissures were deeper than anticipated, and land movement since the project started has created others.

Utility updates

Earlier this year, SoCalGas and Southern California Edison announced they were cutting off gas and power to more than 150 homes within the landslide complex affecting both Rancho Palos Verdes and the city of Rolling Hills.

Since then, Southern California Edison has restored power to some homes, but most are still without gas or power. According to city officials SoCalGas is unable to restore service “due to safety concerns that involve potential pipeline strain, leaks, or damage that could lead to fires or other hazardous incidents.”

How to participate in the City Council meeting

• The Rancho Palos Verdes City Council will have its regular meeting at 7 p.m., Dec. 17, at McTaggart Hall in Hesse Park, where the landslide will be discussed. The meeting will also be live streamed on rpvca.gov. 
• Residents can participate in public comment in person or online at rpvca.gov/participate.
• Residents can also email their comments to cc@rpvca.gov.