Avalanche Control - A New Approach
Hi folks.
For the past year, Mt. Hood Meadows has conducted extensive research on developing an improved avalanche control (AC) program that will provide for the safety of our employees conducting avalanche control, and to better serve skiers by getting our in bounds terrain – in particular Heather and Clark Canyons – open more frequently and routinely after storm cycles. This blog is a continuation of prior blogs addressing snow safety at Mt. Hood Meadows and is intended to:
• Review our in bounds terrain and the associated avalanche threats,
• Inform about current options to mitigate this threat, including current procedures,.
• Present the option we are most likely to pursue and the approvals process required for implementation,
The Terrain
The terrain in Heather and Clark Canyons is big, varied (convex slopes, rock cliffs, steeps, trees, etc.) and uniquely spectacular. Combine this terrain with an ample supply of northwest snowfall and you have the recipe for some incredible skiing, snowboarding, and avalanches. Mitigating avalanche hazards in this varied terrain is challenging, particularly during storm systems. It’s hard to get to -- the Cascade Express chairlift is frequently crippled by a large volume of rime ice and it can’t run early, if at all.
Snowmobiles and snowcats are ineffective in pulling the patrollers uphill through deep snow and whiteout conditions, so patrollers must climb on skis or wade uphill with heavy packs of explosives to reach their control objectives. Under such conditions, more patrollers performing snow safety work is not the answer. In fact, such a strategy would further compound safety and productivity challenges in this area.
Our current avalanche control program is one that we have used effectively, for many years and includes a series of both passive and active measures. Passive methods include avoidance and closure. While there are areas within our permit area which we avoid altogether, we use gated ropelines to manage our avalanche closures, as the map below indicates.
Unfortunately, temporary closures are only respected if they are infrequent and of short duration. Long delays in opening Heather Canyon after a storm cycle frequently lead to closure violations. The threat of lost skiing privileges, a fine or possibly death if overtaken by an avalanche, apparently are insufficient deterrents. Safety of our employees and the public is the primary concern of Mt. Hood Meadows Ski Resort and the Mt. Hood National Forest.
Control Zones are often used to help define the terrain in avalanche control programs. Typically, multiple avalanche paths grouped within one zone may have similar terrain features, similar weather patterns, and require similar hazard reduction measures. You can see the different zones on the map below. Each zone generally requires its own unique approach and technique.
Mt. Hood Meadows ski patrol routinely provides active control measures into these areas, including the use of:
• Compaction – Primarily skier compaction, which works best in Lower Heather Canyon, but must thoroughly disturb every snow layer in order for skier/rider compaction to be effective
• Ski Cutting – A major staple of most ski patrol control teams, but is not suitable for hard or deep slabs on the unconfined convex slopes that prevail in Heather & Clark Canyons,
Deep slabs are possible as shown here in A-zone, beneath the Basalt Cliffs
-- you definitely wouldn’t want to try ski cutting this slab.
• Explosives – Using hand charges is the most common method of Avalanche Control delivery in use at Meadows today. Individual explosive charges weighing from two to ten pounds each are thrown, suspended or placed onto the avalanche path by our control teams.
Despite the inherent and obvious hazards associated with handling explosives, using them can reduce control team members exposure to avalanche hazard.
The sequence below shows the effective use of hand explosives to release a slide in A-zone.
Sometimes a 10 pound explosive isn’t enough so a larger explosive is delivered by tethered sled precisely into a control area.
We also use an avalauncher (like the one pictured) which uses compressed nitrogen to throw a 2.6 pound explosive charge designed to explode on impact. Avalaunchers are often times not effective during storm periods as the light-weight charge can be blown off course. And during storm conditions visual confirmation is not possible to determine whether avalauncher “shots” have been effective.
Here’s one of the key challenges of avalanche control work in Heather and Clark Canyons: Because they both funnel into Lower Heather Canyon all of these zones have to be controlled before the terrain below them can be opened. Our crews have to blast their way from one zone to the next, first controlling the Basalt Cliffs, then Upper Heather ridge, on to Clark Ridge and down to Accordion Bowl.
This also means that all the explosives for this trek must be carried in, so our patrollers are performing this work wearing 70 and 80 pound backpacks filled with explosives. Meanwhile, other teams are controlling Heather Ridge, Clark Canyon and Jacks Woods.
The lower canyon can only be opened once the upper potential avalanche areas have been controlled.
Control teams that climb the ridge to reach the upper Basalt starting zones are faced with a very big challenge. These starting zones are huge unconfined convex rolls that get steeper the farther out you go. These are some of the most dangerous types of slopes for control teams to be on. Control teams here are also frequently hampered by high winds and poor visibility. The snow surface is often wind packed and very firm which requires the hand charges to be tethered to keep them from rolling down the slope. “Tippy-toeing” out onto a huge convex hard slab, in a “whiteout”, to tether a five pound booster to your ski pole is extremely dangerous. There is rarely a safe route, and there is no place to hide.
I have the greatest amount of respect for our patrollers who serve on our control teams. They perform their work professionally and precisely, in extreme and inhospitable conditions, with no margin for error. The graph below shows the number of patrollers on the Basalt and upper Heather Ridge routes conducted over the past several seasons.
So that brings you up to speed on our current avalanche control program.
There are other options to performing control work used in other parts of the country. After careful consideration we’ve determined that most don’t deliver the margin of safety or accuracy that we need here in our challenging environment. For our situation, the safest and the most effective avalanche control measure is a military weapon, an option we are currently studying with the intent to acquire and install. Specifically, a M101A1 105 MM Howitzer like the one pictured below, located at Las Vegas Ski and Snowboard Resort.
The 105 MM Howitzer has the ability to deliver appropriate payloads of explosives to remote and inaccessible starting zones with precise targeting, even during adverse weather conditions. That means that control work can proceed during storms, even in whiteout conditions, confidently and precisely. That will enable any required hand throwing or cutting by teams to proceed more directly to those areas. This means we can open Heather and Clark Canyons more safely and potentially more quickly following storm cycles, depending on the weather and snow conditions. It also means less risk to our patrol crews. These weapons are administered by the US Army Tactical Command based at the arsenal in Rock Island, IL. The army “loans” the equipment to another government agency such as the Forest Service or a state highway department with the cost of equipment refurbishment borne by the proposed user which, in this case, would be Mt. Hood Meadows. Military weapons are used for snow safety programs at other ski areas such as Mammoth, Alpine Meadows, Taos, Jackson Hole, Alta, Las Vegas Ski & Snowboard and by highway departments in Colorado, Wyoming and Washington.
The acquisition of the Howitzer and construction of the building is a top priority for Mt. Hood Meadows. In addition to the normal USFS permitting procedures, which includes environmental analysis in accordance with the National Environmental Policy Act, our plan must also comply with and be approved by the Bureau of Alcohol, Tobacco and Firearms, the Department of Homeland Security and the U.S. Army. We are working closely with Forest Supervisor Gary Larsen, pursuing a plan which could allow us to construct the firing platform and magazine, and acquire the weapon for use as soon as the 2008/2009 ski season, provided USFS permitting can be achieved in the near future. Here is his perspective:
As Forest Supervisor, I was asked to add my perspective to this blog. I have never blogged before, but welcome the opportunity. While every ski area avalanche management situation is unique, there are a set of factors that need to be well-addressed in the administration and management of any ski area avalanche control program. Among them are:
• the level of avalanche risk the public is exposed to and how public exposure to the risk is managed,
• the level of risk assumed by ski area employees and the ski patrol in controlling avalanches,
• the interaction between weather, avalanche risk, and opening of potentially threatened ski runs,
• environmental effects, and
• cost and difficulty of administering and managing the avalanche control program.
We (MHM and Mt. Hood National Forest) have become increasingly concerned with the level of risk the ski patrol and MHM employees are facing in their current routine avalanche control. MHM has explored a variety of methods for control. Representatives from the Mt. Hood National Forest and MHM visited Snowbird ski area in Utah a month ago to examine their avalanche control program because theirs is one of the best in the nation.
We found out that indeed MHM employees and ski patrol are exposed to greater risk than Snowbird employees and ski patrol. We discovered a high level of public acceptance of the use of military weapons and a very effective system for communicating with the public about risks, planned avalanche control times, and a high degree of management of public exposure to avalanche hazard and control. We also discovered that the environmental effects of military weapon use are smaller than with other techniques because of increased accuracy and significantly smaller dud rate. Lastly, we affirmed the importance of using a multi-faceted approach to controlling risks associated with avalanches and avalanche control — a comprehensive avalanche control program.
MHM has made a proposal to the Mt. Hood National Forest to improve its avalanche control program in several respects, the most significant of which is the proposed use of a military weapon. As we have evaluated their proposal, we find it to be comprehensive and well-thought through. If we approve implementation of their proposed program, risks to the Ski Patrol and MHM employees will be reduced very significantly, risks to the public will be significantly reduced, response times after large snow-dumping storms will be shortened significantly allowing use of some of the best runs while snow conditions are still excellent. The overall environmental effects will be less in comparison to their current methods. The one-time initial capital investment required for the proposed avalanche control program will be high due to acquisition and refurbishing the weapon and construction associated with its shelter and explosive storage. The annual operating costs will also be higher than the current approach due primarily to the training requirements necessary to safely operate the weapon. MHM is also including investment in other avalanche control tools as part of its new comprehensive plan.
The only environmental effect changes that will require analysis are for the installation of the new weapon shelter and explosive storage — an analysis that we will conduct under a categorical exclusion. MHM and the Hood River Ranger District are consulting with stakeholders and local officials as MHM finalizes its proposal. We will look forward to considering the proposal when they submit it after having made changes as the result of their consultations. The Hood River District Ranger has indicated to me that she would solicit additional comments from stakeholders when we receive the final proposal before she makes her decision. From my perspective, this proposal by MHM represents a significant long term investment in the safety of the Ski Patrol, MHM employees, and the public, as well as an investment in providing high quality services to the public.
-- Gary Larsen, Forest Supervisor, Mt. Hood National Forest. April 2, 2008