Mountain of Controversy Created : New Effort Under Way to Halt Massive Slide’s Slip to the Sea

They knew the land on which it sat was moving toward the sea when they bought their home on the Palos Verdes Peninsula 17 years ago, but Robert and Jean Smolley couldn’t resist the rural charm that surrounded the place.

Along the way, they made peace with the land and they learned to survive in an area that literally changes from day to day. The constant movement of the Portuguese Bend slide was both a curse and a blessing. It threatened to tear their house apart from time to time, but it also kept their little corner of Rancho Palos Verdes from developing into just another crowded suburban community.

The 1.2 acres on which the home sits belongs to one of the most famous landslides in the world, a mountain of earth that for nearly three decades has moved relentlessly seaward. Repeated efforts to halt it have failed, and some houses have moved as much as 400 feet since the first slide in 1956. A total of 127 homes have been destroyed and many others have been damaged extensively.

Mountain of Controversy

Now, the small city of Rancho Palos Verdes has decided to do battle with the mountain. But the fledgling effort has already brought forth a mountain of controversy, some political, some philosophical, some scientific.

“I don’t think there’s a . . . chance in hell they can do it,” said Robert Smolley, a mechanical engineer whose home is squarely in the middle of the largest of three separate slides in the area.

At the opposite end of the technical dispute is Perry Ehlig, consultant geologist to the city and professor of geology at California State University, Los Angeles, who believes he has been successful in halting--at least temporarily--the slide at Abalone Cove by pumping water out of the geological formation. The city is so impressed with Ehlig’s success at Abalone Cove that it has started installing wells in other locations to see if “dewatering” will have the same results throughout the slide area.

Charles Abbott, the man who will oversee the ambitious and costly project for the city, agrees that the effort to hold back the mountain will be Herculean.

“The magnitude of the mass just overwhelms you,” Abbott said as he stood one recent day at the foot of the slide, looking at giant concrete and steel caissons in the surf. The caissons, five feet in diameter and 30 to 40 feet long, were part of an early effort to stop the slide. They were buried deep below the surface in hope that they could hold back the earth, but the slide ripped them out like toothpicks and thrust them down the hill more than 400 feet to the surf.

‘Boggles the Mind’

It is that kind of brute force, plus the size of the mass that must be stopped, that causes residents like Smolley to took upon the effort with disbelief.

“The magnitude is enormous,” he said. “It just boggles the mind.”

Smolley also thinks that not enough is known about the slide to stop it, and he fears that any measures undertaken at this point may worsen the situation rather than relieve it.

Ehlig has assembled a committee of 17 experts to counsel the city, including representatives of some of the most respected geological engineering firms in Southern California. Arthur G. Keene, geologist for Los Angeles County and a member of Ehlig’s committee, believes the effort could be successful.

“It depends on how far the city is willing to go,” Keene said. “It can be done.”

Keene believes, however, that the scope of what would have to be done might be without precedent.

“It would be a landmark case,” he said.

Ehlig and his associates believe the project can be successful if several fundamental objectives are achieved.

First, the city must install enough wells to pump out what amounts to an underground lake just below the surface of the mountainside. Drilling on the first of the wells has already begun. Second, the city must take whatever measures are necessary to keep the water from coming back. And third, it must literally move part of the mountain, transporting millions of tons of dirt from the higher slopes to the toe of the slide where it would be protected from the pounding surf by a giant retaining wall.

One Step at a Time

If that can be done, Ehlig believes, the mass of the man-made barrier would offset the downward drive of the upper slope.

Abbott, who acts as the city’s public works director but is actually a private citizen under contract with the city, sees the city proceeding one step at a time.

“We’re in a theory stage right now,” he said, although work has already begun on the project’s first stage.

Two wells have been completed in the Portuguese Bend landslide, two others are nearly finished, and some surface grading is under way at a cost of nearly $300,000, Abbott said. Nine monitoring wells have also been installed to measure the impact of the operation on the water table.

“We’ll have to see the results of these wells before deciding what to do next,” he said. If the results are encouraging, the city will install additional wells next year and grade more areas to improve surface drainage.

Abbott said he believes all the dewatering wells that would be required, plus the surface grading, can be completed for between $3 million and $4 million. If that stage is successful, the city could then embark on the more ambitious effort of changing the basic shape of the mountain by moving several million cubic yards of dirt and building a massive retaining wall at the bottom of the slide.

‘Talking Big Bucks’

“You’re talking big bucks there,” he said. Some estimates have placed the cost of that operation at $30 million to $40 million, but the city has not made a precise estimate. That phase of the project would also dramatically change the appearance of one of the most scenic stretches of coastline in Southern California, a move that would undoubtedly provoke a major response from environmentalists.

To finance the project, the city has formed a redevelopment agency, although that approach usually is limited to urban areas. Increases in property values through either new construction or rising real estate prices within the redevelopment area will be set aside to pay for the stabilization project.

Many residents of the area have objected to the city’s designation of their rural retreat as a “blighted” area, one of the prerequisites for eligibility as a renewal project.

They also fear that some of the land the city would want to move lies beneath their houses, meaning the city would have to destroy their homes in order to save them.

Successful stabilization of the mass would return about 500 acres of land to economic viability in an area with some of the most expensive real estate in the country. Vacant lots less than one mile from of the slide area are now selling at prices beginning at $175,000 and rising as high as $400,000, and that kind of appeal is hard for any taxing agency to ignore.

Transition Road

In addition, Abbott said it now costs the city about $200,000 a year to maintain one of the most tortured stretches of road in the country. Palos Verdes Drive South, which runs from Marineland to San Pedro, is the city’s only link between its eastern and western sections, and people who drive it regularly rarely find it the same from one day to the next. The road has moved about 300 feet closer to the ocean during the last three decades, and its contours challenge a car’s suspension.

Movement is constant rather than intermittent in most areas. Ehlig believes the movement ranges up to an average rate of about an inch and a half a day in some areas, although movement is much less in others. In a crude test of his conclusion, a Times reporter placed a marker on secure ground alongside an embankment that is believed to be the upper edge of the slide. A few days later, the bank had moved away from the marker several inches.

Adding fuel to the controversy is the fact that much of what is known about the landslide is conjecture based upon a limited understanding of the region rather than scientific proof of the sort that some of the engineers who live in the city would like to have. The problem with any landslide of this scope is that the slide plane--the geological formation on which the mass slides downhill--is far below the surface and cannot be examined except through a few drillings and in the areas where the slide plane breaks the surface.

Ehlig believes he understands the slide plane reasonably well, but even he admits there may be some surprises. He has studied the area for many years, and he has reached some conclusions, however.

Volcanic Ash Beds

The slide plane is primarily composed of “soft, waxy bentonite beds,” he said in an early report on the problem. He described bentonite as a volcanic ash deposited in the area during earlier geologic times, and he said the beds are “as much as 70 feet thick” and include highly expansive clay minerals.

When the bentonite is saturated with water, Ehlig said, it deforms easily, providing a slick surface for the mass to slide on.

That problem would be relieved substantially, he believes, if the ground water in the area could be lowered to the point that the bentonite remains relatively dry and thus less prone to geological failure.

But that may be far more difficult than it would seem because of the scope of the problem. Several canyons feed rainwater into depressions in the slide basin, where it is trapped and percolates into the soil. One operation high on the agenda would be to provide avenues for that runoff to reach the sea, but that would involve carving deep canyons from the slopes to the ocean.

Water also enters the formation through natural underground aquifers that permit ground water to move great distances, and no one is certain where those aquifers are.

The water increases the slide potential in several ways. It “buoys” the ground up, thus reducing the resistance to sliding caused by friction. It also adds weight to the upper slopes, and it causes the bentonite to deform, in a sense turning the clay into a bed of ball bearings.

The water table is no more than 40 to 50 feet below the ground in some areas, and the slide plane in some cases is more than 100 feet deeper. Thus to be effective the water table would have to be lowered substantially, an effort some critics believe would take years and might not even be economically feasible.

Any movement, for example, could shear off the wells, running up the cost of the project substantially. The wells would also have to be able to remove more water than now enters the formation, and no one is quite sure how much that is.

Ehlig believes the slide plane slopes fairly gently toward the sea, an unusual situation for a landslide area, and he is convinced that when the slide plane reaches the coastline, it turns upward. He said drillings and tiltmeters--devices that measure tilting of the mass--have led him to that conclusion.

If he is right, a massive barrier along the toe would tend to hold back the slide because it would have to be lifted by any downward movement of the hillside, sort of like a geological ski jump.

Ehlig maintains that all three slides are separate geological entities, and all three are encompassed by the city of Rancho Palos Verdes. That makes it convenient from a political standpoint in that any effort to end the slide does not have to involve other municipal jurisdictions.

Sharp Disagreement

But Smolley, perhaps the strongest critic of the proposal, sharply disagrees with Ehlig’s understanding of the slides.

The newest and most active of the three slides is in Klondike Canyon along the eastern edge of the known slide region. Coastal areas of the canyon began moving about five years ago, at times dramatically. Last year, landslides hit an inland area above the canyon, long known as the Flying Triangle, in the city of Rolling Hills. Three homes have been destroyed there in the past few months, and others are threatened.

Historically, slides in the area have moved first along the coast, and later in the upland areas.

Smolley maintains that is happening now in Klondike Canyon, and slides that have destroyed the homes in Rolling Hills are part of the same slide that is pushing an undeveloped coastal area into the sea.

It is a critical point because of an earlier warning by Ehlig. Ehlig warned the city several years ago it would be important not to dewater lower slopes first while leaving higher elevations saturated because that would increase the driving force of the higher areas and probably add to the sliding.

“I see no connection between the Flying Triangle and the Klondike Canyon slide,” Ehlig said recently.

Watched Around World

That conclusion would be difficult for most laymen to accept if they stood at the Flying Triangle and peered down into the canyon below. But Ehlig has studied the area for years and he insists he is right. Keene, the county geologist, has told the city of Rolling Hills that he also believes the slide problem there is independent of the slides on the lower slopes.

No matter who is right, the slide stabilization effort in Rancho Palos Verdes will be watched by geologists around the world for new insights into the cause and control of landslides.

Several geologists said they knew of no other area in the world where a stabilization project of this magnitude has been successful, although some pointed to lesser slides that have been stopped through similar measures.

“The issue is how much effort would be required,” said Dr. Bruce Clark, principal engineering geologist for Leighton Associates, one of Southern California’s most prestigious geological engineering firms. “Similar measures have been successful on a smaller scale, so there’s no reason to think it wouldn’t work here,” he added.

For Charles Abbott, the man who must bear the major responsibility for the effort, the project will be extraordinary.

“When I was a kid,” he said, “I saw the Empire State Building and I thought that was the most challenging engineering feat in the world.

“Now,” he added, “I think this is.”