Rancho Palos Verdes Erects Barrier to Stop Wave Erosion in Slide Area

Concerned about erosion where the Portuguese Bend landslide meets the sea, Rancho Palos Verdes is spending $50,000 to install an 800-foot barrier to protect the bluffs.

“This is temporary . . . to try to safeguard the stabilization work that has been done above,” said Charles Abbott, the city public works consultant who is in charge of the project to tame the 32-year-old landslide, which has destroyed more than 130 homes.

The city has slowed the slide by relocating soil from its top to the bottom, creating a bulwark against further sliding. But the waves are eroding the bluffs at the foot of the slide, and the dirt carried out to sea has formed a plume that has all but destroyed marine life in the area.

“A large storm could really wipe us out,” Abbott said.

The barrier consists of stacked wire baskets containing stones taken from the beach. It is considered a stopgap measure until the city can find the money for what it really wants: an offshore seawall that would shield the toe of the slide from the surf.

Abbott said a seawall is at least three years away. The city, which estimates the cost of that work at between $10 million and $20 million, is seeing whether the money can be obtained from the federal government or the ports of Los Angeles and Long Beach.

Construction of the barrier, which began a month ago and is half completed, was prompted by heavy waves in March, which Abbott said were stronger than the waves generated by the major storms of 1983. The stone-filled baskets are terraced and reach a height of 6 feet at the edge of the bluffs.

“The purpose is to keep the normal wave action away from the bottom of the bluff so it does not continue to erode,” Abbott said.

The technique of using such stone-filled baskets dates back to ancient Egypt, where they were used to control Nile flooding, according to the company that holds a patent on the long and shallow devices and is supplying them to the city.

Effort Called a Success

After spending two years and $2 million to fight the 250-acre landslide, the city is calling its effort a success. Abbott said that northward of Palos Verdes Drive South--the main portion of the slide--land movement is holding at less than three-hundredths of an inch a day. Movement was as high as 2 inches a day in some spots before work started, he said.

“The slide is not stopped; it’s still moving. But when we set out to do this, we said if it got down to a tenth of an inch a day, we would call it successful,” he said. “We’ve exceeded that.”

Because of the constantly moving land, the city used to spend $225,000 a year to regrade and patch a four-fifths-of-a-mile section of Palos Verdes Drive South, according to an environmental report on the road project. The road, which was relocated northward in March, has developed some cracks but will not require major work for two or three years, Abbott said.

In addition to moving earth from the top of the slide to the bottom, the stabilization program involved installing drains to prevent water from reaching and lubricating the slick underground plane on which the land is sliding. Wells also were drilled to remove water.

City officials, however, have long said that coastal stabilization is required for the landslide to be completely controlled. Councilman Mel Hughes calls it “the last link” in the fight.

To that end, the city is hoping for positive results from a $250,000 Army Corps of Engineers study of the four landslides that plague Rancho Palos Verdes and Rolling Hills. The study, which started in October, will focus on causes of the slides and how stopping shoreline erosion might affect them.

Alan Alcorn, a section chief with the corps, said the study will determine whether there are feasible ways to halt the slide and if there is a legitimate federal interest in such a project, such as the protection of a public roadway or enhancing coastal recreation.

If there is federal interest, he said, the second phase would focus on devising a plan to protect the coastline, with costs shared by the federal government and the cities.

The city also has proposed that the ports of Los Angeles and Long Beach consider providing money for the seawall as part of the “mitigation” they will be required to do because of a massive port expansion project. Extensive dredging and creation of new landfill will destroy marine habitats, and the ports are required by law to counter that damage by enhancing the environment elsewhere.

“This is one of the few local jobs that may qualify because of the proximity,” said Public Works Director George Wentz. “It is a local project right here at home.”

Lillian Kawasaki, environmental management director with the Port of Los Angeles, said decisions on mitigation projects are made by a task force involving the two ports and several other public agencies, including federal and state wildlife and marine agencies.

She said that at this point, the task force is inclined toward restoring wetlands and has given the Rancho Palos Verdes project a “moderate to low” priority. She said the city has to demonstrate the value of the marine habitat that would be created by stopping the landslide.

The city has hired a former California Coastal Commission member with wide experience dealing with public agencies as a consultant under a 6-month, $12,000 contract. He will press the city’s case with the port’s task force and also will explore other ways to pay for a seawall.

“We will look at the environmental damage from the sand plume,” said the consultant, Barna Szabo, who was a coastal commissioner from 1973 to 1976 and now represents clients dealing with regulatory agencies. “I think we can show conclusively that damage is severe and extensive and that it would be incumbent on federal and state agencies to assist the city in restoring the fish and marine life that was there before.”