Slide Has ‘Slowed Considerably’ With Anaheim Pumping Effort : Disaster: Geologist working for city says he’s encouraged but warns that too little is known about subsurface conditions of hillside to say problem is solved.

The city’s geologist said Friday that the Anaheim Hills landslide has “slowed considerably” and that pumping out hundreds of thousands of gallons of water from the hillside appeared to be helping.

“We think (the pumping operation) is working fairly well,” said Mark McLarty, a geologist under contract with the city. “But the reality is we know so little about the subsurface conditions here that it’s impossible to tell.”

In a press briefing early Friday morning, McLarty said he was encouraged by the slowing, but warned that the homeowners were far from being out of danger.

The land that slid is still “sitting very precariously” on the hillside and might get worse with additional rain or land movement, McLarty said.

“I can’t give you a long-range prognosis,” he said about the landslide area’s future stability. “We just don’t know.”

One potential problem, he said, is that the landslide appears to be larger than initially thought. Geologists now suspect that it extends north of Serrano Avenue, encompassing Swarthmore, Loyola and Lehigh drives and Vassar Circle.

That part of the slide area, however, has not yet caused problems and may never do so, McLarty said. The section seems to be more stable than the rest of the slide area because it was buried under “compacted fill” and was graded in a way that minimized the potential of sliding, he said.

“It’s not what’s moving and not what’s potentially going to move,” McLarty said.

But the geologist freely admitted that he didn’t have much information on the ancient landslide, which apparently dates back millions of years. He said he plans to gather more data on the slide now that it appears that the ground movement is slowing.

Earlier this week, city crews began installing measuring devices to study the slide’s movement.

But collecting the amount of data needed to make recommendations on how to stop the landslide is a process that McLarty estimated could take nine months or longer.

During that time, some of the 45 evacuated homeowners might not be allowed to move back home, city officials have said.

Also at the briefing, McLarty revealed that he had seen several documents which identified potential landslides in the Anaheim Hills area before its development.

“But not to the magnitude of this,” he said.

McLarty said the developers made efforts to mitigate landslide problems before building. But he was uncertain if that work had been done to all the slide areas identified in city documents.

McLarty said his main concern is not what occurred in the past, but rather what to do about the present and future problems of the landslide.

Finding out who knew about landslide potential before development in the area “is going to be an important issue down the road, obviously, but right now it’s really not important to me,” he said.