Laguna Fears Flooding if Rain Is Heavy

With a 60% chance of rain today, the California Conservation Corps and county workers Wednesday were hurriedly clearing brush from drainage channels and depositing bales of straw to prevent mudslides in burned-out Laguna Beach canyons and streets.

“We are very much concerned and we are working very hard in the Laguna Beach area to minimize the risk of potential flooding,” said Tom Connelie, the county’s assistant public works manager.

“The slopes have been denuded, so there is less to keep the soil from washing away in heavy rains.”

Light rain arrived Wednesday evening in parts of north Orange County, and there is a 60% chance of rain today, according to James McCutcheon, a meteorologist with WeatherData, which provides forecasts for The Times. “We’re expecting the heaviest rains sometime between late (Wednesday night) and early morning, changing to showers in the early afternoon,” he said.

In anticipation, about 10,000 straw bales have been installed on hillsides to stop debris from being carried away by flooding.

“It slows down the water so it doesn’t build up a lot of energy and cause erosion,” said Bob Collacott, who works for Woodward-Clyde Consultants and is directing the erosion control effort.

The company, hired by Laguna Beach on Nov. 1 to develop an erosion-control plan for fire-damaged areas, consulted the cities of Oakland and Berkeley after the devastating 1991 fire.

In some spots, he said, pre-assembled silt fences are being set up to block debris from flowing into the streets.

Also, “tens of thousands” of gravel-filled burlap bags have been placed around storm drains to let water flow through while keeping out debris that could clog the system, Collacott said.

Helping the emergency effort, hundreds of local residents and high school students filled the gravel bags while Conservation Corps crews cleared debris from curbs and gutters along Park Avenue and Laguna Canyon Road.

Myriad agencies, including the U.S. Department of Agriculture Soil Conservation Service, the county’s Environmental Management Agency, the state Department of Forestry, and the city of Laguna Beach, are working on the anti-erosion effort.

“Everybody’s been working like one well-oiled machine,” Collacott said. “It’s been going very well. The goal has been to identify things quickly and to get everybody working as hard as they can to protect the city.”

Four Conservation Corps crews from as far away as Sacramento are working in the Ortega Highway fire area and another 12 crews are working in the Laguna Beach area.

Laguna Beach municipal services director Terry Brandt spent Wednesday coordinating the city’s efforts.

“We’re just doing whatever we can at this point, given our resources, to try to prepare for the rain,” he said. “There’s a potential for a problem; that’s why we’re doing everything we can to try to prepare for it.”

The City Council will hold a special session on Saturday at 9 a.m. with Woodward-Clyde to discuss erosion prevention, followed by a workshop at 10 a.m. for canyon residents on protecting their homes.

Soil specialists say it is too early to predict how much of the area would slide if heavy rains arrive.

And whether the fire has worsened the landslide-prone geologic materials has not been determined, said Carol Forrest, a consultant and soil specialist with Woodward-Clyde Consultants.

When there is a lot of loose organic material on the surface, a high-temperature fire can cause a water-resistant “hydrophobic” layer to form below the surface.

“When there is a heavy rain, the material above becomes saturated and slides off,” she said. “We have seen some evidence of hydrophobicity, but not extensive.”

Eric Vinson, assistant state soil scientist with the USDA’s Soil Conservation Service, said a short but intense rain would move off most of the ash layer.

“Hopefully, if the rains do come, they’re gentle,” he said.