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Hillside building rules likely to be toughened

October 17, 2018 GMT

The Town Council is fed up with landslides after the one on West Broadway cost $9.4 million to fix.

And to prevent more slides the council is working to update town regulations on development on steep slopes and unstable soil. Regan Kohlhardt, associate long-range planner for the town and Teton County, said the current policies are insufficient and unclear.

“Some clarification would be helpful,” she said at Monday’s council meeting.

One of the main problems, Kohlhardt said, is that current standards for evaluating slope stability consider only the angle of the slope, while ignoring soil conditions, past slides and other factors.


Guidelines about how to mitigate potential soil disturbances aren’t specified and requirements for geotechnical reports “are, quite frankly, nonexistent,” Kohlhardt said.

Leading up to the slide that undermined the butte near Budge Drive in 2014, the town approved grading and construction on the slope several times based on geotechnical analyses that deemed the work safe.

Based on practices in other communities, Kohlhardt said, the town should specify requirements for soil and slope reports and map geological hazards to locate potential dangers around town. Perhaps most critical, she suggested the town seek advice from trained geologists and engineers, either through third-party contractors or by hiring them as staff.

“It’s important to have that expertise available to the community,” Kohlhardt said, “to ensure development is safe.”

She also recommended that the town hire a consultant to help produce the regulations, rather than leaving it to the council and town staff, all laypeople in the field of geoengineering. A stakeholder group to review the regulations might be formed.

Councilor Don Frank said he thinks the town should draw a distinction between two types of developments: those that involve only the property owner, who can decide what risks to bear without harming anyone else, and those in which soil disturbance could cause landslides that affect people downhill.

“I think there’s two different standards we have to look at,” Frank said.

Reed Armijo, CEO of Jorgensen Architects, praised the town’s efforts to improve how it handles such tricky development situations.

“There are so many factors that affect the stability of a site,” he said. “It’s pretty complex, and we really applaud looking at raising the bar.”