By Sue Pascoe
Editor
During the heavy rainstorms Jan. 19-23, Malibu Canyon Road and Topanga Canyon Road were both closed after boulders came crashing down on the roadway. The California Incline was shut down for brief periods because of mud, and several lanes of Sunset Boulevard were closed by debris. Near Porto Marina on Pacific Coast Highway, an apparent waterspout tore off the top of a truck, which flew into power lines and caused the highway to be closed.
The U.S. Geological Survey has identified landslide hazards in Southern California, and it will come as no surprise to longtime residents that Pacific Palisades is prominent on the site.
What causes landslides and mudslides? According to the USGS, “In Southern California, at least 25 cm (10 inches) of rainfall during the winter is needed to nearly saturate the ground. After this point, a rain burst of 5-6 mm (0.2 to 0.25 inches of rain) in one hour has been observed to trigger abundant shallow landslides land movement.”
Photo courtesy U.S. Geological Survey
Water acts as a lubricant between soil particles, and the strength of saturated ground is pulled down by gravity. An entire hillside can begin flowing downhill if sufficiently soaked. Since July 1, the Palisades has received nearly 16 inches of rain, most of which has fallen since just before Christmas.
Jim O’Connor, a research hydrologist with the USGS, explained how mudslides can be prevented in a March 2014 National Geographic story.
“Strategies to decrease the risk of mudslides include draining water off hillsides, armoring the bases of hills so they are not undercut by rivers, and ‘loading the toe,’” O’Connor said. “In the case of ‘loading the toe,’ engineers put heavy mass, such as large rocks, at the base of a hill to try to anchor the slope and prevent it from coming loose.” O’Connor noted that the piles of rock that are often seen at the base of road cuts are the most visible example of that strategy. At a September Community Council meeting, Palisades Bowl residents charged that Bowl owner Eddie Biggs was cutting into the Asilomar hillside above their mobile home park, just north of Temescal Canyon Road, along PCH.
The News found that the California Coastal Commission gave Biggs permission to take out 4,000 cubic ft. of soil and cut the toe.
First documented in 1959, there are two landslides on the Asilomar hillside, between El Medio and Almar Avenues. One starts 90 feet below the surface, extends into the Pacific Ocean, and is considered inactive. The other, 35 feet down, is continually moving. The city owns the upper third of the hill, roughly down to Puerto del Mar, which was made impassable in 2005 after heavy rains buckled the roadway and caused 12 homes in Palisades Bowl to be red-tagged.
Biggs owns the bottom part of the hill below the road. The adjacent Tahitian Terrace (also mobile homes) at 16001 PCH, owned by the McDonald family (Azul Pacifico), owns the land below Asilomar nearest Temescal Canyon.
In giving Biggs permission to cut the toe, the commission wrote: “The work is designed not to address the larger landslide that covers the approximately 17 acres, but to address the sloughing and minor movement that is occurring along the toe of the slope. Staff is recommending approval of the proposed Coastal Development Permit amendment with four special conditions: 1.) require the applicant to maintain all of special conditions imposed with the original Coastal Development Permit No. 5- 08-245; 2.) ensure conformance with the geo-technical report recommendations; 3.) ensure the applicant complies with the landscape and irrigation plan; and 4.) indemnifying the Coastal Commission from third-party litigation costs.”
Since mobile home parks come under the jurisdiction of the California State Housing and Communication Development, the News contacted HCD in September in regards to Biggs’ cutting the toe of Asilomar. In a return email, HCD analyst Alicia Murillo responded, “The park has the required permits from both HCD and the Coastal Commission for grading. Plans submitted to HCD were stamped by a geological engineer and approved by the Department. An HCD field inspector and supervisor were onsite yesterday (9/13/2016) monitoring work being done.”
The News followed up with Murillo in December and asked when inspectors had last visited the site. An HCD district representative was at Palisades Bowl on Dec. 6, monitoring work. She wrote in an email, “The contractor did obtain the necessary permit from CalOSHA for the shoring of the trenches as required by the approved plans. Construction is progressing.”
Coastal Commission Public Information Officer Noaki Schwartz responded by email to the News on Jan. 18.
“HCD and the Coastal Commission share jurisdiction; however, our purview is the Coastal Act and HCD should be reviewing projects for consistency with building code requirements. A project that receives a CDP does not resolve HCD from their jurisdictional duties. If HCD, local government or a private citizen reports to us that the applicant it not complying with conditions of a permit, we will look into the matter to determine if the project is in compliance with the CDP.” Schwartz said residents can call Coastal’s Long Beach office (562) 590-5071.
In addition to Asilomar, several slides have also occurred along the Via de las Olas bluffs, especially the “killer slide” in 1958 that covered PCH. In 2005, a large amount of earth tumbled down near the bluff park. In addition to the Via and Asilomar bluffs, residents should know where the landslides or mudslides have occurred previously in the Palisades and be alert for warning signs that the earth may be moving.
- Look for tilted trees, telephone poles, fences or walls and for new holes or bare spots on hillsides.
- Listen for rumbling sounds that might indicate an approaching landslide or mudslide.
- When driving, be alert for roads that may be blocked or closed because of collapsed pavement or debris.
If a resident sees a landslide or mudslide starting, move to the nearest high ground in a direction away from the path of the slide. If rocks and debris are approaching, run for the nearest shelter and take cover (under a desk, table or other piece of sturdy furniture).
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