Hanging on to the hills

By CLAIR ENLOW
Landscape Northwest Editor

Don Kehoe is hard to reach. He doesnt like to talk on the phone while hes on a hillside or where a hillside used to be. The changing Northwest landscape is changing fast these days, and thats why Kehoe is there. Crumbling cliffs, landslides and sinkholes are all an important part of his business. He brings design to landscape disasters, and prevention to potential slide sites.

Its been a busy winter, and it will be a busy summer, he said.

Relandscaped Leschi hillside with modified crib wall construction. Photos courtesy of Magic Gardens, Inc.

Kehoes 16-person landscape design and construction company, Magic Gardens Inc., has been based in Monroe for the last 18 years.

Two years ago, the disastrous combination of snow melt and heavy rains in the span of a few winter weeks brought Magic Gardens a great deal of business. Since then, Kehoe has worked with the City of Seattle and with various structural and geotechnical firms to address the effects of large slides on city property as well as damage and potential damage at many private addresses. Among his projects was an Alki site where a hillside slammed against the walls of two condominiums.

Kehoes work typically involves three very important elements: retaining systems, drainage and smart planting. Kehoe has worked with a lot of soldier piles and pipe. But when it comes to keeping a hill in place, the best allies are plants, according to Kehoe.

Kehoe works with two employees at slide site.

You dont want to have to water your hillside, he said.

His star list of Northwest native slope holders includes native rose, vine maples, Oregon grape, snow berry, salal and smooth sumac. All of them have great color, he said. Sword ferns will survive on a west facing hillside in the worst conditions. Unlike some Northwest natives, all of these plants can be purchased in nurseries, said Kehoe.

Among the best hillside holders are native tall trees, he said. Unfortunately, 180-foot Douglas fir, hemlock and western red cedar tend to interfere with the views that move people to build on steep slopes in the first place. Low-lying shore pines are a good alternative.

The different plants that we choose and mix together form a community of root systems, said Kehoe. We can cover both the surface and give strength and stability to the sub-surface.

This 1986 hillslide in Leschi destroyed the house at lower left.

Kehoe lists the terrible habits of blackberry bushes. After they rapidly take over, nothing else grows. No light penetrates, he said.

Aggressive in the sun, theyre wimpy underground. They have an insignificant root system. So when the water hits, and the ground goes. The blackberries? They just readjust a little bit, said Kehoe.

Then theres ivy. This plant also has insignificant root systems. It even skips over the ground above the original root while it takes over. Then it grows up around native trees and kills them.

Kehoe is not always on a hill. We do a lot of permitting, putting the plan and the bid together, he said. Court testimony and legal work have also taken some time lately.

Kehoe has been very active in several landscape contractors associations, as well as the state and Snohomish County farm bureaus. He is on advisory committees for horticulture programs at Edmonds and South Seattle community colleges.

Drainage is installed behind a small retaining wall at Richmond Beach last year.

These grounds are totally saturated in the Pacific Northwest right now, said Kehoe. Faces of hillsides are falling off, sinkholes are growing and there are general landslides.

From Everett to Redondo Beach to Orcas Island, the firm is busy repairing damage and reducing the threat of slide-related disaster while designing and constructing landscapes.

Inspections are now a large part of his business.

Just the other day, he said, he was on a hillside at the request of a property owner, checking for signs of danger. He discovered a 10-foot-square, four-foot-deep sinkhole right on a property line. He notified the owners, and when they visited the site a week later, the hole was eight feet deep and considerably wider.

A load of crushed rock and some new drainage has now stabilized the hill. If no one had paid attention to this, it would have been the sinkhole that ate Seattle, said Kehoe.

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