Residents of six San Clemente homes who were evacuated after a Sept. 3 landslide won't know until at least late next week whether it will be safe for them to return, a city official and geologists said Friday.
Originally, it had been hoped that a decision on the fate of the houses, left hanging on the edge of a 20-foot escarpment, would be reached by last Friday, but delays in work by two teams of geologists prolonged the process.
"The results of borings should be available in seven to 10 days, and should provide information regarding whether or not the residences remain unsafe for occupancy, or whether the residents may be allowed to return to their homes," said Tom Dailey, the city's fire protection director.
On Friday, the 200 block of Via Alegre still was closed to traffic and was quiet except for drilling by employees of Leighton & Associates of Irvine, a geological firm hired by the city. They were punching two holes, each 2 feet in diameter and 60 to 70 feet deep, in the middle of the street.
"From this work, we hope to get a cross-section of the slide area, and to determine whether city property (the street) is involved and whether more movement can be expected or has occurred since the slide," said Beach Leighton, head of the firm. "So far, it appears there has been no more earth movement."
The Leighton group had to wait until another firm of geologists, G.A. Nicoll & Associates of Tustin, had drilled five exploratory holes on the slope in the slide area itself, which hangs over one fairway of the Shorecliff Golf Course.
"They had to wait to use the same drilling rig," Dailey said.
Hugh Marley, chief engineer for the Nicoll company, which was hired by Estrella Properties Ltd., owners of the golf course and large portions of the slopes on which the slippage took place, said the test holes show that the slide material is about 40 feet thick, mostly of man-made fill dirt. He said preliminary data indicates ground water, connected with seepage into a small creek along the golf course fairway, "could be a contributing factor" to the slide.
"Some clay seams in the slope have ruptured," he said, "and water can act as a lubricant (to cause slippage) and also creates an uplifting effect, a buoyancy which weakens the soil."