Calling El Nino’s Bluff
Three years ago, the idea of putting up artificial rock to help reinforce a storm-ravaged bluff was so innovative that it got a wary reception.
Rock facades along Pacific Coast Highway? Disneyland West, claimed many critics who took aim at government’s willingness to spend $3 million to bolster the bluff where a massive, 600-foot-wide slide damaged five homes in 1993.
Despite the initial skepticism, the artificial structure with its unique steel-cable design has held firm against intense El Nino storms.
“We feel very safe here,” said Richard Vaughn, who rebuilt his home on La Ventana, the street atop the bluff, after the slide. But he feels the new bluff was an “irritating investment” because he and some neighbors had to contribute $200,000 toward the reinforcement project.
Bob Boyer, one of Vaughn’s neighbors whose home does not enjoy bluff protection, said he envies his neighbors who do.
“I wished they would have done the whole hill,” Boyer said. “But the city was charging each homeowner $50 a foot and that was just blackmail.”
City officials say the unusual reinforcement was a wise decision.
“It’s one of the safest places along the entire Southern California coast,” said Mort August, Dana Point’s public works director and city engineer.
Not only has it been rock-solid, but the design won an award of distinction last year from the American Public Works Assn., a Kansas City, Mo.-based national organization of 24,000 members.
“It was cited as the best example of what public works does in response to emergencies like this,” August said.
Mark Allen, 38, owner of San Juan Capistrano-based Boulderscape, which manufactured the facade, said he still gets comments about the hillside.
“We get reactions all the time,” Allen said. “People have come up to me and have told me that they like it after all this time.”
Boulderscape was one of the subcontractors on Dana Point’s bluff reconstruction project. After engineering firms designed how to reinforce the devastated bluff top, Allen’s company was called in to give the effort a natural look.
That meant using mesh and sculpting concrete that was then colored and tinted by artisans to give it a realistic look. It’s the same rock found on Disneyland’s Matterhorn, Splash Mountain and other well-known, artificial structures.
Beneath its face, the false rock is solid engineering built to endure the ravages of time, according to August.
“We looked at the types of events we could have over the next 100 years,” August said, “and built it to that design.”
The structure was made of huge, nail-like tie-back anchors, drilled 75 feet into the bedrock to hold a concrete wall that keeps the soil in place. Design engineers were from Nolte Engineers, and the geotechnical engineering firm that created the concrete nail design was Leighton & Associates. Both firms are in Irvine.
“If you think of laying a piece of wood on a hillside and using nails to hold it up, you get the idea,” August said. “Only in this case, the nails are 12-inch diameter concrete cylinders, drilled 75 feet and connected to stainless steel cables. We had 68 of those nails along the bluff.”
The disaster occurred Feb. 22, 1993, and it took nearly a year of wrangling between different cities, and agencies, before 44,000 tons of dirt were cleared and the bluffs braced.
The project was funded by Dana Point, San Clemente, the California Coastal Commission, the California Department of Transportation, the Federal Highway Administration, the state Office of Emergency Safety and affected property owners.
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David Reyes can be reached at (714) 248-2150 and david.reyes@latimes.com
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Keeping Up a Good Face
La Ventana’s retaining wall, known as a “bluffscape,” is sculpted to blend with the hillsides. With the wall in place, sculptors take molds of the natural landscape, then use them to re-create the terrain. How the reinforced bluff was constructed:
1. 12-inch diameter concrete tie-back anchors drilled 75 feet into bedrock
2. Anchors connect to a mat of stainless-steel cables, which holds concrete walls in place
3. Cages made from molds filled with concrete, outer coating applied; sculptors use paint and texture to match terrain
Fast Facts
* Wall ranges in height from 75 to 90 feet
* 68 tie-back anchors hold 600 feet of wall in place
* 44,000 tons of dirt excavated to build wall
* Sculpted concrete same “rock” found on Disneyland’s Matterhorn and Splash Mountain
Sources: City of Dana Point, Times reports; Researched by APRIL JACKSON / Los Angeles Times