Landslide season: What homeowners can do to prevent problems

Perched on a hill above Seattle's Golden Gardens Park, a house with a spectacular view has a spectacular problem: landslides.

City geotechnical experts Tuesday explained how this home, and others on steep, slide-prone slopes, can be protected when heavy rains soak the soil and send hillsides sliding.

At the house above Golden Gardens, which has a history of slide problems, the owners moved the drainage away from the hillside so water doesn't flood the slope and lead to a slide, and pilings were built to protect the home from sliding, too.

"It's important that drains discharge where they should," said Rob McIntosh, a geological technician with the city's Department of Planning and Development. What's important, he said, is that fixes not be so expensive that homeowners can't afford them.

Officially the wet season begins Nov. 1, said Bryan Stevens, department spokesman. He said that in an average wet year there may be 30 slides in the city, but in the wet season of 1996-97 there were 300 slides.

Officials can't say how much rain should be worrisome, but McIntosh said the U.S. Geological Survey considers a half-inch of rain a day to be reason for concern.

The city is urging property owners on slopes and landslide areas to clear drains and take other steps. Residents should check downspouts to make sure they are functioning and are routed to a safe location. And they should inspect slopes for signs of movement, such as cracks in the ground or tilting trees.

A city landslide study found that 86 percent of landslides were caused by human activity such as excavation, fill placed on steep slopes, broken pipes and uncontrolled stormwater.

Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com