The Orange County Register, November 18th, 2006
Charles Quilter recalls the precise moment at 11:58 p.m. on Feb. 23, 1998, when his Laguna Canyon dreams slipped away in a second. It was a singular rainy night in a heavy El Niño year.
“We had drenching rains since December, but we hadn’t been too worried. Then close to midnight a heavy rain cell hung above our home and all at once we heard a roar,” said Quilter, a retired commercial pilot and a 34-year resident of the canyon.
Charles and wife, Ann, survived the devastating debris flow when 15 tons of wet soil came rumbling through their hillside community, taking the lives of two of their neighbors with it.
“You may not think about your hillside until something like this happens.” Quilter said. “But a real bad time to check your slope for safety is right in the middle of a downpour.”
A moderate El Niño is predicted this year, meaning there is the potential for more rain than normal. But heavy rains are a possibility any year. Homeowners who live on slopes, near slopes, or at the bottom of slopes should conduct safety checks soon and prepare their properties.
John Foster, a Cal State Fullerton engineering geology professor, says the most important task that a homeowner can do to prepare for rain is control the flow of water.
“Homeowners need to take a preemptive attitude in protecting their property by directing water to a safe place – away from the hill, toward the street and ultimately to the nearest storm drain,” he said.
Southern California has a history of hillsides slipping during rainstorms. There are several reasons that land slips way, but the two most relevant for our region are gravity and water. Gravity continually pulls soils and sand in a downward direction, and rain can make it happen faster.
“You can’t stop a hill from coming down if it wants to,” said Jim Coleman, geotechnical engineer for Coleman Geotechnical in Irvine, “but homeowners can definitely minimize the risk.”
Homeowners with older properties might be more concerned with slope stability than those who live in newer neighborhoods.
“Slopes engineered before the 1970s had slacker codes to build by. And some very early slopes had few rules at all about how they were engineered,” Coleman said.
Quilter adds that anybody who lives on a hillside in Southern California needs to understand the risks. He suggests hill-dwelling homeowners take an active role to ensure that their slopes are safe and stable.
“Work with your uphill and downhill neighbors as much as possible,” he said. “Take an active role in where runoff water is directed, which is away from the slope and toward the street. Do all you can to protect your land, and don’t wait for the experts to recommend it.”
The combined wisdom of Quilter, Foster and Coleman:
•Install rain gutters and downspouts if you don’t have them.
•Make sure all rain gutters and downspouts are clear and functioning.
•Make sure the water from downspouts is directed, as far as necessary, to a safe place. Don’t let water pool around your foundation, especially if your house sits below street level. Even if you don’t have a slope, you could risk flooding.
•It is one thing to prepare for normal rain flows, but also have a system for peak flow periods when rain is heavy. Ordinary drains and downspouts can easily get overwhelmed.
•When heavy rain is predicted, hike down the street and make sure your local storm drain is clear of debris.
•Do not direct water toward a neighbor’s property. Work with your neighbors to be sure their water isn’t directed toward your property. The joint goal is to make sure all the water on all the properties is directed toward the street and ultimately toward the storm drain.
•Do not allow water to pool near the rim of a downward slope. Ponding water near a slope can cause slumping failures. Drain water away from these low areas with French drains or dry streambeds.
•Don’t add water to a waterlogged situation. During the rainy season, make sure your sprinkler clocks are off.
•If you live in a hillside community, make sure your terrace drains are clear. Terrace drains are constructed into every engineered hill and required by county construction codes. They may be covered with vegetation. Find them and make sure they are clear of debris.
•While checking your slope, look for surface erosion, soil that has washed away in vertical gullies that might be getting deeper. You might need to plant additional vegetation on hillsides with surface problems to prevent erosion. Gullies that are a foot or more across should be looked at by an engineer.
•It is too late now to plant for this year’s rainy season, and in fact you don’t want to disturb the soil. Quick fixes for surface erosion may be to apply mulch or plastic. Plan to revegetate your hillside in the spring with deep-rooted native plants and acacia.
•Homeowners on hillsides composed of heavy soil such as clay should check their slope for cracks or fissures. These cracks continue to fill with water and get deeper with each rainy season. Horizontal cracks that are an inch wide and 10 to 15 feet long should be looked at by an engineer.
•If you are worried about any part of your slope, cover the area with plastic and consult an engineer.
Check your phone directory for geotechnical engineers who specialize in slope and hillside stability. Don’t wait until the rainy season to do it – Coleman says engineers don’t like to get wet.
DANGER ZONE: A 2005 landslide took its toll on houses in the Bluebird Canyon area of Laguna Beach.
