Earth moves in Tree Haus

Construction resumes after repeat of soil slumping

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Foundation construction has resumed on a single-family building site in the Tree Haus subdivision where the soil has slumped more than once this year.

Routt County Chief Building Official Carl Dunham confirmed this week that a full building permit has been issued to Jack and Nicole Hamm of Englewood for construction of a two-story home at lot 114 in Tree Haus, just off River Road. The excavated site has been visible to motorists on U.S. Highway 40 passing the Mount Werner Road exit for more than 12 months.

Excavation on the steeply pitched site began in September 2005, and efforts to stabilize the hillside were undertaken at the recommendation of a soils engineering firm. However, an engineer for Northwest Colorado Consultants recommended against building a home on the lot.

The engineer recommended a series of measures to guard against the potential for both soils expansion and movement. The engineer also reiterated what one of his colleagues had concluded in a 1994 engineering report on the lot - soil movement has taken place in the area in the past and there are no assurances movements won't take place in the future.

The engineering firm went on to state that following its recommendations for drainage systems and basing the foundation on caissons drilled into the ground would not entirely eliminate the risk of soil movement.

When construction began in fall 2005, steel plates were used to help secure the construction site. However, the foundation was not completed before winter. After near record snowfall and a rapid snowmelt, construction resumed in the spring and evidence of slope instability was observed.

A neighbor who lives near the site wrote to the Routt County Regional Building Department to express concerns about soil movement within 10 feet of his own home. The neighbor reported both soil subsidence and the appearance of a "fissure."

The construction site was idle over the summer, but work resumed with a new contractor in September. Twenty-two additional plates were installed to further stabilize the construction site. However, September and October produced precipitation that was 200 percent of average, and the saturated soils slumped again.

Subsequently, an engineering firm specializing in a technique called "soil nailing" was brought in to stabilize the hill. A similar technique was used in the cuts and fills used to construct the Alpine Slide on Howelsen Hill.

Dunham said his department was comfortable issuing a full building permit given the measures taken to stabilize the site.

"The engineer designed a foundation that would hold the hillside," he said.

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