City crews will wait until after the busy Fourth of July holiday to make repairs to a mudslide that scarred the slalom course at Howelsen Hill Ski Area late last winter.
Jeff Nelson, ski complex and rodeo supervisor for the city, said this isn't the first time that portion of the ski hill has experienced a mudslide.
"After a seven-year drought, we made extra snow on that part of the hill last fall, and then we had a wet spring," Nelson said. "We're working with a soils engineering company, and all of the things you would have expected happened."
In the future, his crews will be more consistent about plowing snow off the steep slope as soon as the ski trail closes. They already do that to avoid similar mud slides on the steep landing hills of Howelsen's ski-jumping facilities.
The city acquired new snowmaking guns last year, and Nelson's crew was intent on blowing more snow in late fall to get Steamboat Springs Winter Sports Club skiers on the training runs as early as possible. But it would be an exaggeration to say the additional snowmaking caused the mudslide, Nelson said.
"It was the combination of a lot of things, and snowmaking was definitely part of it," Nelson said.
Nelson said he's become more aware of how temperature inversions in downtown Steamboat affect the ski slope just across the Yampa River from the heart of the city.
The steepness of Howelsen Hill creates a situation where temperatures vary significantly in small increments up the slope, Nelson said.
The coldest air is at the bottom of the slope. Nighttime air temperatures grow progressively warmer as one moves up the hill. The higher you go, the more likely the soil is to be covered by an insulating blanket of snow before it freezes. Grooming patterns also affect how deep the ground will freeze, Nelson said.
When abundant snow fell on Howelsen Hill this spring, the soft ground became super-saturated with moisture.
Fixing the aftermath of the mudslide won't be too difficult, Nelson predicted. The heavy rains of early June didn't cause any additional damage, but they brought excess soils disturbed in the original slide to the bottom of the hill. That will make the job of loading and redistributing the excess soil easier, Nelson said. A contractor probably will be retained to use a bulldozer to blend the sharp cuts left by the slide back into the terrain.
When it's time to revegetate the disturbed soil on the slalom hill, crews will be able to use plastic mesh from the construction site of the new K68 jump to anchor germinating grasses, Nelson said.