Safety Zone: Deadly Trees

How to avoid the dangers of snags

PHOTO KIRK KEOGH
At least 32 individuals are known to have lost their lives to snags since 1934. Incidents involving snags are one of the top three causes of accidental deaths in the USFS.

It happened again this year: In North Carolina, 31-year-old career firefighter Todd Blanchard was attempting to extinguish a tree ignited by lightning when it fell, fatally injuring him. Then, in mid-September, a near tragedy occurred on the 6,500-acre Missouri Ridge fire-use fire in the Frank Church Wilderness outside McCall, Idaho, when a sawyer sustained a skull fracture after a snag struck his hardhat. Several other near misses involving trees or snags have occurred this past year.

Snags Defined
According to the National Wildfire Coordinating Group’s (NWCG) latest Glossary of Wildland Fire Terminology (Publication Management System 205, January 2005) a snag is defined as a standing dead tree or part of a dead tree from which the leaves and smaller branches have fallen. (It’s also called a stub, if it’s less than 20 feet tall.) Usually the fuel moisture level is much lower in these trees than live trees, which allows them to burn more readily and at a faster pace. These trees can also fall faster and without much warning. (Seemingly “green” trees can be snags as well.)

According to the Historical Wildland Firefighter Fatality Report provided by the NWCG’s Safety and Health Working Team (SHWT), at least 32 individuals are known to have lost their lives to snags since 1934. (For the complete report, go to http://www.nifc.gov/reports/). Incidents involving hazardous trees are one of the top three causes of accidental deaths in the U.S. Forest Service, along with motor vehicle accidents and wildfire entrapments.

During the past five years, 24 SAFENET reports involving snags have been filed. Not all the problems reported in these SAFENETS were caused by snags, however, the snags were worthy enough to be mentioned in the report.

Snag Hazards
So what are the potential hazard indicators for snags and green trees? Common signs include:

Trees that have been burning for an extended period of time;
Species of trees (e.g., cypress) that are known to have a shallow root system or are susceptible to rot;
Numerous downed trees;
Dead or broken tops of trees and limbs overhead;
Accumulation of downed tree limbs;
Absence of needles, bark or limbs;
Leaning or hung-up trees; and
Trees that are smoldering or smoking part way up their trunk.

Snag Conditions
There are a number of well-documented and well-known environmental and operational conditions that will increase your likelihood of encountering a snag. These include:

Strong winds: When a strong wind picks up, expect limbs to break and fall. A branch may be weakened or broken from a previous wind event. Some agencies employ guidelines instructing their personnel to leave the woods when winds reach a sustained speed of 20 mph. Does your agency have a recommended guideline?
Steep slopes: Whenever working on a sloping terrain, always consider posting lookouts—especially when crews work above you. A fallen tree doesn’t always stay where it fell; it can bounce and roll down the hill. So not only must you watch your footing, but you must also watch for what could be rolling down the hill toward you.
Diseased or bug-killed areas: Beetles infested many areas in the west and the southeastern United States this year, weakening and killing trees, making them more likely to become snags.
Night operations: Have you ever pulled a night shift and heard the very audible snap of a tree somewhere? Maybe above you? Although operations personnel often prefer the advantages of cooler, less active nighttime hours, your risk of becoming injured from a snag increases when your visibility decreases.
Helicopter bucket drops and rotor downdrafts:Anticipate that bucket operations will cause weakened trees to fall, even if it’s only a Type 3 airship working in your division. Their bucket drops average about 500-plus lbs. Is that enough weight to make a tree fall?
Retardant drops: Some folks still think it’s cool to get “pinked” while a silver tube is painting your division’s slope, but if you thought a Type 3 helicopter might cause a snag to drop, why wouldn’t a retardant drop of several thousand gallons do the same thing?
Vibrations from heavy equipment and motor vehicles: I remember cypress trees dropping all around me on a muck fire in Pasco County (Fla.) years ago as I drove a light pick-up truck down a two-trail road. If you’re in an area with many pieces of equipment working or trees that have shallow root systems, expect snags to fall.
Explosive use in fireline construction: The same principals from the point above apply here when using heavy equipment. With explosives, you must also watch out for flying debris.

What Should You Do?
What steps and behaviors should you use to mitigate the danger of snags on your fire? Snag risks should first be reduced by the incident management team or overhead supervision through routine communications that outline their concerns. The incident action plan (IAP) should include a list of all mitigation steps. Specifically, special instructions should be included in the safety message and the division assignment forms (ICS 204). Snag safety should also be a topic included in all daily briefing(s) and tailgate safety sessions. The safety officer, plans chief and operations chief should address their concerns in form ICS 215a. Large tracts of hazard trees can also be identified on IAP maps.

Further, a safety officer or other trained, competent person should mark hazard trees with yellow-and-black striped flagging or “Killer Tree” flagging. However, never be lulled into thinking all hazard trees have been marked; some hazard trees can be mistaken for healthy trees.

There are many other ways to mitigate hazard tree situations. Here’s a quick list of some tried and true methods and related topics for tailgate safety sessions. Important: Some methods listed below should only be conducted by experienced sawyers/safety officers/operations personnel.

Establish walk-away criteria;
Secure the area;
Consider blasting;
Relocate work area(s);
Consider push/pull options with heavy equipment;
Conduct a risk assessment using your situational checklist;
Review the role and responsibilities of a swamper and a lookout;
Use proper personal protective equipment; and
Establish clear and marked lookouts, communications, escape routes and safety zones (LCES).

Finally, there are several excellent courses and publications available on snag safety, including S-212: Chainsaw Training Course update; Interagency Hazard Tree Job Hazard Assessment; or some of the regional publications such as The Hazard Tree Awareness, Prevention Program-R8 or Hazard Tree Safety/Up-the-Ante in Region 1.

Remember: Snags will accompany every wildland fire, prescribed fire operation or fire-use program, so the next time you go into the woods, look up, look down, look all around.

Gene Madden, an SOFI, is the chairman of the NWCG Safety and Health Working Team and a member of the NWCG Emergency Medical Support Group. Madden is employed as the division safety officer for the Florida Division of Forestry and is an IOFI and a medical unit leader. E-mail him at maddeng@doacs.state.fl.us.