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TAMING A LANDSLIDE : Residents, Rancho P.V. Clash Over Schedule of Road Work

October 15, 1987|GERALD FARIS | Times Staff Writer

Encouraged by what they view as a successful first phase of a $2-million program to tame the 31-year-old Portuguese Bend landslide, members of the Rancho Palos Verdes city staff are urging that the next segment of work get under way within a month.

Some residents of the area disagree, however, saying it is too soon to know whether the program is working.

The second phase will involve relocating the sliding Palos Verdes Drive South roadway onto more stable ground close to its original right of way.

"The big advantage to doing it this fall is that things have been dry and we are in good condition to move ahead," said city geologist Perry Ehlig.

In a report to the city in June, Ehlig said that although movement continues in the slide, it is at a "greatly reduced rate."

Massive Shifting

Officials attribute the slowdown to the massive shifting of 600,000 cubic yards of dirt from the top of the slide--where it was exerting downward pressure--to the bottom of the slide, where it could act as a block against further movement. As part of the $1-million first phase, drainage systems also were put in to prevent water from reaching the slide plane.

In the northern 50 acres of the 260-acre slide, the rate of movement--formerly 4.6 to 10 feet per year--has slowed to 1 or 1.4 feet and may have stopped altogether in some places, Ehlig said. Lower portions of the slide are moving faster but were slowed by the grading work. For example, Ehlig said, the 60-acre east-central portion of the slide, which is above Palos Verdes Drive South, is moving at half the rate it was three years ago.

More large-scale earth movement is proposed for the second phase, in which an additional 500,000 cubic yards would be taken from northern portions of the slide and placed on the new Palos Verdes Drive South roadbed to provide stability for the relocated road. The cost of that work is estimated at $500,000.

A lengthy environmental impact report on the slide work asserts that a safe alignment of the road--the only coastal road connecting Rancho Palos Verdes and San Pedro--is impossible in the present location. "Moving the road north, to as near pre-slide alignment as possible, would place it in an alignment that is moving much slower," the report states.

According to the Ehlig report, the present road is in an area that is moving 23.8 feet and 32.9 feet a year at two monuments that measure movement. But land where the road will be moved to is moving from 7.3 to 14 feet a year.

Maintenance Costs

Relocation would cost $321,900, but the environmental report states that the $225,000 a year it currently costs the city to regrade and patch the ever-moving road would be reduced to $37,143 because of less land movement.

Charles Abbott, city public works consultant who is in charge of the stabilization project, favors the realignment. He said in terms of safety and maintenance costs, there is no comparison between keeping the present road and moving it.

The relocated road also would have a drainage system to pipe runoff directly to the ocean. According to the report, runoff from the present road goes directly into slide fissures and depressions and makes the movement worse.

During the life of the slide, the road has moved seaward in a curving direction, and the present road is as much as 350 feet away from where it used to be. The slide was triggered in 1956 by work on the Crenshaw Boulevard extension, which was immediately abandoned and never completed.

The City Council, sitting as the Redevelopment Agency, could give the go-ahead Nov. 4 after the public comment period for the extensive environmental impact report ends.

Inclined to Move Ahead

"Ehlig is strongly recommending that we move ahead, and the (agency) is, from my perspective, inclined to move that way," said Mayor Mel Hughes.

Abbott said that with approval, the work could be under way by Nov. 15 and completed within 90 days.

But in Portuguese Bend, some residents say officials may not fully understand the landslide and are advising caution. In a letter to the city, resident Andrew H. Sargent, an attorney, said: "Prudence calls for a go-slow attitude. . . . To proceed without allowing sufficient time to pass to intelligently assess the impact of the previous actions is negligent."

Longtime resident Jeanne Smolley said that because of recent dry years, it is difficult to know how much of the slowdown of the slide is attributable to the grading. "We would have to wait and see," she said. "Water has a great deal of weight, and weight is the driving force."

The road relocation appears to be a major sore point with Portuguese Bend residents.

"We are a small community . . . the people who live on the landslide and take care of it," said Daphne Clarke of Peppertree Drive. "We are all pretty well agreed in favor of stabilization, but we don't want the road (relocated). They can do the work with the road where it is."

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