Darrell Sapp, Post-Gazette Dirt , rocks and trees cover the northbound lanes along a stretch of Route 65 yesterday.

By Joe Grata and Caitlin Cleary, Pittsburgh Post-Gazette

The ground was in a constant state of motion yesterday at the site of a massive landslide in Kilbuck.

Boulders the size of refrigerators tumbled down the steep and crumbling hillside onto the deserted Ohio River Boulevard below. Tree limbs cracked and groaned under the weight of an estimated half-million cubic yards of dirt and rocks -- a continuous cascade that billowed down on top of the normally busy artery into Pittsburgh, completely blocking it.

The landslide started Tuesday night at the site of the former Dixmont State Hospital, where the controversial River Pointe Plaza shopping complex, opposed by a local citizens group, is to be anchored by a Wal-Mart Supercenter. A new access road from Ohio River Boulevard had been cut into the abutting hillside, but was buried by the slide.

Ohio River Boulevard (Route 65) remained closed to traffic, and could stay that way for days, possibly more than a week, while workers continue the seemingly Sisyphean challenge of clearing the slide.

"Where the slide separated, it resembles the fault line of an earthquake," Pennsylvania Department of Transportation spokesman Jim Struzzi said. "There's nothing we can do until it stops [moving]," and then engineers will outline a course of action.

An emergency worker assigned to guard the area overnight reported that the hill had been advancing about 5 feet every half-hour.

By mid-morning, the mass of earth and stone that had already moved measured about 500 feet wide and 20 feet high.

Earth-moving equipment clawed at the leading edge of the slide, where the creeping mountain had partially covered one of three mainline tracks of Norfolk Southern Railway. The slide also snapped a utility pole in two, and the lines sagged along the right of way.

The railroad switched traffic to the two sets of tracks nearest the Ohio River. Freight trains were backed up in both directions, waiting for their turn to pass.

As a precaution, Columbia Gas of Pennsylvania isolated and shut off a section of an 8-inch-diameter natural gas distribution line that passes through the landslide area. The utility company is using two alternate feeds, so no customers lost service.

Back in April, officials were forced to close Ohio River Boulevard at the site when blasting went awry and sent debris onto the highway. It was closed for more than a day after that incident.

This time, the slide is far worse and will take much longer to clear, Mr. Struzzi said.

Equipment yesterday had begun to cut a wide, level horizontal "shelf" midway up the slope to relieve pressure, intercept more sliding material and help stabilize the hill.

That work apparently will have to be finished, or nearly finished, before other equipment can safely start removing the dirt on the highway below.

An average of 17,000 vehicles a day that travel the highway were being detoured, along with buses on the Port Authority's 16A Ohio River Boulevard and OV Ohio Valley Flyer routes.

Traffic will continue to be sent on a circuitous North Hills detour -- Camp Horne Road, Mount Nebo Road and Interstate 79 -- at a time when a PennDOT contractor is working in the vicinity, limiting traffic on I-79 and connecting roads in preparation for two years of reconstruction on the interstate.

To make matters worse, a two-car accident at Mount Nebo and Arndt roads snarled traffic on the main detour during yesterday's evening rush.

Angry motorists railed at the situation, directing most of their ire at the developer.

Larry Barger of Moon spent 80 minutes traveling Downtown yesterday morning, twice as long as his normal commute.

"Traffic from the west was horrendous," he said. "Why should a developer be permitted to repeatedly close a state road and cause significant inconvenience to the driving public without penalty?"

An official with Penn Development, listed as the site contractor, refused to comment on the landslide, referring all questions to ASC Development Inc., a Pittsburgh-based developer of regional shopping centers, and its general contractor, Chevy Chase Construction.

Officials with ASC did not return phone calls. A man inside the Chevy Chase Construction trailer on the site of the landslide would not answer repeated knocks at the door.

Opposition to the 207-acre River Pointe Plaza project began in early 2002, when Communities First!, a group of about 400 residents from towns along the Ohio River corridor, launched a series of appeals and legal challenges, objecting to the shopping center's impacts on traffic, the environment and property values.

PennDOT's only involvement with the developer was issuing a highway occupancy permit for an access road, including requirements for adding left-turn standby lanes and traffic signals. Last year, Communities First! unsuccessfully sought to intervene and persuade PennDOT to deny the permit.

Mr. Struzzi said the cost of the cleanup and highway damage after the April incident was assessed to the developer. PennDOT didn't levy any fine, but the Department of Environmental Protection may have, he said, because of the blasting.

A spokesperson for the DEP did not return phone calls seeking confirmation of such a penalty.

According to PennDOT officials, the material that shifted and slid appears to be fill for the plateau being created on top of the hill for the shopping plaza and parking lot. They said PennDOT has not been involved in what has been taking place at the site since March, when the work started.

Mr. Struzzi said the contractor had enough excavation equipment on the site to clear the highway, but PennDOT was evaluating whether it may get involved to speed the process and reopen Ohio River Boulevard to traffic sooner.

Any costs incurred by PennDOT, plus damage to the highway, will be assessed against the developer as it was in April, Mr. Struzzi said.

"The developer will be held wholly accountable," he said.

"Activists from that area warned both the DEP and PennDOT that this landslide would happen if the Wal-Mart were built there," said Jeanne K. Clark, director of communication for PennFuture, an anti-sprawl group. "Today's mess is child's play compared to what is going to happen on Route 65 when the store opens."