The new avalanche mitigation study, which looks at Behrends Avenue and White Subdivision avalanche paths, gave eight recommendations to the city — including home buy-out options and a second crossing to Douglas Island.
The City and Borough of Juneau received a Federal Emergency Management Agency grant to update its hazard’s mitigation plan, including avalanche mitigation. City Emergency Programs Manager Tom Mattice, also the avalanche forecaster for the city, explained the report for the Assembly Committee of the Whole on Monday.
The study was conducted by WSL Institute for Snow and Avalanche Research, a company in Davos, Switzerland. Mattice said the company was chosen because it is using new computer technology that shows impact pressure.
Mattice emphasized that the study was not a hazards map for the city, but instead a mitigation plan that evaluated past studies and included modeling and mapping.
Mattice showed an example of how the company looked at avalanche zones by playing a video clip. The video showed a computer animation of a swath of snow at the top of Mount Juneau represented in green. As the video played, it showed that snow pack become an avalanche and how it fell down the mountain. As it fell, the colors changed to how dense the snow was. This computer program for SLF is called Rapid Mass Movements, RAMMS. This system does not currently evaluate “powder snow” avalanches — very dry avalanches.
The company did those analyses for 10-year, 30-year, and 300-year avalanche scenarios. The consultant visited Juneau in April to evaluate the avalanche paths.
The study was also submitted with a note of caution.
“The city should know that while SLF can and does attempt to uphold the highest professional standards, the state of science and engineering knowledge is incomplete, and does not always permit certainty,” it states. “The complex phenomena involved in avalanches cannot be perfectly evaluated and predicted, and methods used to predict avalanche behavior change as new research becomes available.”
The study looked at the Hart report from 1967 and 1968, the La Chapelle report of 1968, the Geophysical Hazards Investigation by the city in 1972, and the Juneau Area Mass-Wasting and Snow Avalanche Analysis of 1992.
The new report describes the Behrends Avenue avalanche path as “very complex” with a mean inclination of 35-40 degrees — which is actually pretty steep, with some points as much as a 50 degree inclination.
“This steep part of the avalanche track favors the formation of powder snow avalanches,” it states.
Further in the Behrends zone, the consultant references an incident in Galtuer.
“...Galtuer has a mean inclination from the crown line to the destruction area of 29 degrees, in February 1999 an extreme avalanche in this path killed 31 people,” it states. “If the Behrends Avenue avalanche path would be situated at a higher elevation, for example the Swiss Alps, large avalanches would probably be frequently observed.”
Mattice said Juneau is fortunate because of its elevation and because of the rain/snow in winter, making the mountainside more stable.
SLF evaluated the avalanche path and found that the 10-year avalanche does not reach Behrends Avenue, the 30-year avalanche would stop at Egan Drive, and the 300-year avalanche extends into Gastineau Channel.
Mattice said SLF evaluated several options for mitigations including artificial release (it did not recommend further detonation because it could trigger a significantly larger and several avalanches), preventative road closures on Glacier Highway and Egan Drive when the risk of a powder avalanche is high (though it notes it would be quite time consuming), snow supporting structures and deflecting dams. The consultant did not recommend snow supporting structures at this time because of the quantity needed. Deflecting dams would not be effective in the case of powder avalanches. It also looked at direct protection of buildings, which essentially would built structures around the mountain side of a home — like a stone wall. Mattice said the structure would cost more than homes on the site. There are 28 residential houses in the severe hazard zone and 12 in the zone designated as “special engineering.”
The White subdivision also was similarly assessed. SLF found the concern of a secondary avalanche release when creating an artificial avalanche release is still present. Damage potential in this zone is five residential houses in the severe hazard zone and eight buildings in the “special engineering” zone.
“The exposed buildings are not protected, e.g. reinforced, and seem to be very vulnerable against avalanche impacts,” the study found.
The study recommends closure of Egan Drive and Glacier Highway and evacuations should the city conduct artificial releases, since this location would be easier to conduct those mitigations. It does not recommend artificial release without evacuation. It did find that the White Subdivision is better suited for an artificial release. SLF recommended further study to determine if some kind of snow supporting structures would be appropriate for this location, starting with snow stakes and a geotechnical evaluation because of the mudflows. It advised that avalanche dams in this area would be very difficult because of the steep slope, but catching dams may be feasible. It could also address the mass-wasting issue during the rest of the year.
SLF recommended implementing mitigations in this area before considering housing buyouts for this subdivision.
For more the full report, see bit.ly/zJhWhp.
• Contact reporter Sarah Day at 523-2279 or at sarah.day@juneauempire.com.
Comments (23)
Add commentWhen's the last time...
...an avalanche made it to Egan Drive? Any time in the past 30 years? 50 years? 70?
Not saying it hasn't - just curious.
How often is Anchorage hit
How often is Anchorage hit with a 1964 earth quake? How often do jets get flown into the side of a large commercial building?
Just because it does not happen regularly does not mean we should not evaluate the risks, hazards and mitigation options.
If the city ignored the problem and "the big one" slid down the hill and homes were destroyed i am sure people will want to know why nothing has been done.
This is a great positive step. Evaluate the hazard with real data and evaluate the options. Great job setting this up Tom.
Planes flown into buildings?
Is that a force of nature? Don't you just love the taxpayer funded mitigation for that scenario? Three cheers for TSA! Why don't we do a study on tsunami mitigation addressing tidal waves generated at Point Arden? That should be worth an extra 1% sales tax. CBJ could get a bigger land grab than just Behrends Avenue. The second crossing will take it's own 1% cut.
2nd crossing? So I can still
2nd crossing? So I can still get to my hockey games or so Douglasites can still get to Costco?
Buyout
KTUU news just reported that the buyout would involve 33 homes and cost $22,000,000. Thats $666,000 a home. A pretty lucrative return if it is true.
repost
repost
old article
This is an old article talking about the same issue.
http://juneauempire.com/stories/010205/loc_20050102001.shtml
Im just sort of confused why another study was necessary, it appears to show basically the same thing as the info talked about in the older article.
2nd crossing
We can have as many crossings as we want if an avalanche wipes out the bridge... just take a boat!
If we hire a bureaucrat with a title
Hire an emergency manager and we will have incessant studies of emergencies, requests for funding, creeping bureaucracy, and searches for more tax money. This fellow has learned how Juneau works in a very short time; homeowners receive a big payday so they can retire down south, realtors and developers have a possible increase in housing stock, Goldbelt gets its second crossing so they can sell land for the new houses, global warming adherents can attribute all the costs to their religious beliefs, and the bureaucrat we didn't need has a real chance at longevity. How can we lose?
Emergency Programs manager
Universities nationwide usually have this managerial position, so it doesn't seem unreasonable that the capital city of Alaska would also.
For the person who linked a similar story from a few years ago and questions the point of this new study, it seems to me that having an outside expert analysis concur with earlier research strengthens their conclusions.
But, "those convinced against their will are of the same opinion still"..
@Durian
If you say so, but it seems to me that there are several factors to consider when undertaking a study, one being what, if anything, do they plan to do with the results? The prior study was pretty thorough and Im not sure what new information they thought they would obtain. I can understand a study being done as an update to information already obtained if in fact they were considering action now. Also while the study talks about the need for a second crossing, I dont see any mention of adding extra emergency preparedness measures such as medivac helicopters, or other means of emergency evacuation that could be brought in if a road was blocked but maybe that was in the study but not mentioned in the Empire article.
Hysteria
Wow, Karla, you have an awesome memory for someone who was not even two years old when the 1962 slide occurred! And, while many of your points are interesting, I take issue with the proposal to deny people of their property--even if only for a portion of the year--without fully compensating them. Property tax abatement is not sufficient.
Put this in perspective: In the 130-year history of this town, the 1962 avalanche was the worst by far. A few roofs were damaged, and some walls and windows were breached. Neither the probability nor the magnitude of this risk is sufficient to take away people's homes.
True, children aren't able to make the purchasing decisions or risk assessments for their parents. But again, put this in perspective. More children have been killed, paralyzed and otherwise gravely injured on Juneau school busses in the past 50 years, than people of any age in Juneau avalanches--including skiers, hikers and mountaineers who taunt the risk. So if absolute bubble protection for children is the goal, let's address the greater risks before depriving people of their hard-earned homes.
I'm in favor of monitoring avalanche risks and broadcasting warnings. Preventative measures are worthwhile. But the government cannot micromanage my personal risk assessment or take my property.
Avalance danger
The avalanche in 1962 did indeed cross Behrends Avenue and reach the channel but did "not" close the channel. In further years there was great controversy over the White Subdivision.
Buyer be ware !!!!!
The rest of us should not have to pay for those that don't do their "due diligence:"
\]
It did slide all the way to the water in the past
My grandfather talked of seeing longliners pulling up next to the slide and using it for a source of Ice in the 1920's and 1930's he recalled that back then there were no houses in the way and explained that it was nearly an annual event back then.
He, like nearly every "oldtimer" claimed the snow got a lot deeper back then but interestingly he also always claimed that the snow was a lot drier back then and claimed that particular slide would only happen when there had been a lot of dry powder snow and no wind.
How many more hazard studies
How many more hazard studies do we need? I am already being forced to pay flood insurance for a place with no known flood history. Now we can add avalanche hazard to the Juneau home owners woes. Doesnt matter that in anyones memory there has only been one, in '62. Lets just take more available land out of the pool, so we can all fight over the last remaining postage stamp sized lot, that is if we can afford it.
And buy them out for $600K?!?!?! Hey, I'm listed as being in a flood zone. Buy me out for $600K!!!!!!!!
Grandfathers had the best fish stories
Ah ha, that's a cool story. I come from a family of Juneau longliners. In those days, it was extremely uncommon to fish in the winter because they caught all they needed during the unlimited spring and summer seasons. Further, the fishing grounds were close to home and there would be no need to ice halibut or cod in the winter air because they would have returned to port before the fish perished--freezing was more likely. That is, if they chose to brave the icebergs from Taku Inlet that were rampant in those days, and the freezing spray. Although that drier snow would have turned into a muddy slurpee in the channel, I am skeptical anyone would risk their precious boats to pull up to an amorphous blob of slush in what was then mostly an undredged and extremely shallow channel. This leads me to distrust your grandfather's claim it was an annual event. My father lived in that area from the late 20's through the 50's, and he was always unimpressed by talk of avalanche risk.
Sorry, Karla
Thank you for clarifying.
So if I understand you correctly now, you don't actually recall the wind blast or your father's tense times, as you said. Instead, you recall reading what other people said about those events, and you're relying on the accuracy of their memories and trusting that their versions are not tainted by any bias or agenda. That's very different.
Frankly, I'm a bit relieved because I thought you were a brilliant student in elementary school. Since I was in Juneau at the time of the avalanche, and I have no memory of it whatsoever, I was feeling a little inadequate.
Ok
Karla, I was only taking issue with what I apparently misread as your awesome percipient abilities before the age of two, when you had not yet even moved to Juneau. Now I understand your knowledge is more forensic in nature. As for the McGinnis avalanche, I think that was obvious to everyone who ventured "out the road" in those days. We would hike to the top and slide down the fresh grassy chute on the pockets of our bell bottomed Levis that spring.
Anyway, don't displace people from their homes. But if you must, then fully compensate them. That's all.
this really strikes me as a
this really strikes me as a personal responsibility / buyer beware issue and not the government’s nor the publics responsibility to buy out these home owners.
How many of these homes have changed hands over the years? If they have changed hands then the new owners certainly have the responsibility.
Has a sub emergency station been placed at N. Douglas yet,
if there is a need then lets do this rather than a second crossing.