2000-04-17 04:00:00 PDT BERKELEY -- The city of Berkeley will try to persuade state transportation officials this week to go along with its newest design for a "living wall" of vegetation along Interstate 80.
Bolstered by a report by a team of city-sponsored seismic experts, Berkeley's new design calls for the wall's foundation to be bolted down instead by steel-reinforced concrete beams laid across compacted soil in the pattern of railroad tracks.
If » California Department of Transportation engineers reject the plan, Berkeley may have to put up with a traditional concrete-block sound wall or be left with nothing at all.
Berkeley has been working with Caltrans for seven years to design a terraced wall of flowers and shrubs to shield its largest green space, Aquatic Park, from freeway noise.
City officials will meet with Caltrans engineers on Wednesday to challenge their contention that the living wall must be anchored by 50-foot-deep concrete piles and a retaining wall to prevent it from toppling in a major earthquake.
"They didn't really let us know about this new design until last week and so they are putting us under the gun," said Caltrans spokesman » Greg Bayol.
Berkeley planners, meanwhile, say they received a final report from Caltrans in January, only a few months before funding for the project was due to run out. But Bayol said Caltrans notified the city in September that extra seismic precautions would be necessary.
The Caltrans requirements pushed the cost of a mile-long stretch of living wall from an original estimate of $2.9 million to $13 million. Only $3.5 million in funding is available for the project, based upon the cost of a 5,600-foot standard concrete sound wall, the type that Caltrans has been building along suburban highways.
Two » University of California engineers and a geologist, who proposed the new design for the city, said it would cost less than half of what Caltrans has proposed. But to stay within budget, only 3,100 feet of wall could be built.
In the event of an earthquake, the engineering consultants said, the pyramid-shaped wall would not endanger lives or impede freeway traffic even if it is badly damaged. But they said the piles recommended by Caltrans would actually magnify ground shaking on the structure.
If Berkeley and Caltrans reach agreement, the new design would be presented at an April 27 meeting of the » Alameda County Congestion Management Agency. Otherwise, the agency has told the city it will recommend to the » California Transportation Commission that a standard concrete wall be built.
Berkeley is requesting a 20- month extension for the project. But if an extension is not approved by the transportation commission in June, the $3.5 million in funding will expire and no sound barrier will be built. Bayol said if Caltrans agrees to Berkeley's new design, the city will have to accept liability if it collapses during an earthquake.
Rene Cardinaux, Berkeley's public works director, said he will recommend to the City Council that the city agree to pay for fixing a living wall damaged by a quake if the costs exceed reconstructing a collapsed concrete sound wall.
"We're convinced there's not a safety issue (with the new design)," said Cardinaux. "It's not going to fall down on anybody."