Could blasting work on Mt. Juneau?

Posted: Friday, December 19, 2008

Preemptive avalanche blasting could be in Mount Juneau's future, but only if the community wants it, the slope conditions are right, and money is available, the city's newly hired avalanche forecaster told avalanche area residents Wednesday.

Tom Mattice said "active mitigation" - that's avalanche-speak for proactively trying to prevent serious slides, as opposed to just predicting when they are most likely to happen - is not something Juneau can expect anytime soon, if at all. Exploring its feasibility and, if appropriate, implementing a system is a long-term goal with no set timeline, Mattice said.

Mattice and Emergency Manager Mike Branum discussed the possibility at a community meeting Wednesday that 23 people attended. Most were residents of the White and Behrends neighborhoods, parts of which lie in the path of several of Mount Juneau's avalanche chutes. Sixty-two homes, a hotel, two sections of Egan Drive and most of the Aurora Basin boat harbor sit in the country's most dangerous avalanche zone, local avalanche expert Bill Glude has said.

Mattice and Branum emphasized that there's more at stake here than the people and property directly in the slide paths. An avalanche at the wrong time could sweep school buses that stack up near Juneau-Douglas High School into Gastineau Channel and sever downtown from the rest of the city. Branum and Mattice said one of their goals is preparing the city for a once-in-a-century avalanche.

The potential options for active avalanche mitigation on Mount Juneau are limited. The general idea is to trigger smaller, safe and carefully planned avalanches instead of letting snow accumulate to more dangerous levels. Mattice said the two obvious options are helicoptering up to lay explosives by hand or dropping explosives from a helicopter.

Juneau's frequent rain and fog makes both methods unreliable because they require good weather and high visibility. Mattice said that leaves a proprietary system called Gazex, or something similar to it.

The Gazex system, manufactured since 1988 by a French company, installs big spigot-shaped tubes on mountainsides. The tubes are connected to storage tanks with a mixture of oxygen and propane. The explosive gases are triggered remotely and will work in any weather conditions.

But before such a system could even be entertained, Mattice said an in-depth slope analysis and modeling study needs to be done. The analysis would work out all the math and physics with the particulars of Mount Juneau to determine if there's enough cushion between where smaller slides would stop and homes begin.

"It may be such that the slope is too steep. Snow would just keep on coming," Mattice said.

Mattice said he didn't have an estimate of costs associated with a study, but that part of his job is finding a way to pay for it, possibly through grants or partnering with other organizations.

For now, Mattice said he's working on building a daily avalanche forecast to be posted on the city's Web site. At Wednesday's meeting, he solicited suggestions and polled the group on interest in phone or e-mail alerts and their frequency.

One man said the warnings had created a "danger tedium" in the past. Another said it was "Chicken Little all winter long."

There was a range of preferences, so no matter what Mattice does he's likely to end up like Goldilocks for some but the Boy Who Cried Wolf for others.

One woman expressed concern about the effect on property values and selling her home if the public is constantly made to think an avalanche is imminent.

Mattice didn't have a broad solution, but said he'd put enough information online to help people make more nuanced decisions. He also said he'd only make the extra effort to publicize forecasts with local media when the risk is at its greatest.

"I think it's good they're getting people involved in the area," said Brian Messing, a White neighborhood resident.



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