Natural Notes: Tree Worker Safety

This post consists of my notes from a lecture on tree worker safety as part of my training to become a certified arborist by the International Society of Arborculture.  The speaker was Phillip Prohaska, a natural resources specialist with the Forest Preserves of Cook County and his lecture took place on February 27, 2015 at the Salt Creek Resource Management facility in Willow Springs, Illinois.  Please note that some graphics in this post were used from outside sources.  

Introduction
Working around trees is risky.  Safety is very important.  With respect to safety regulations, a statement that includes the word "shall" is a mandatory safety requirement.  A statement with the word "should" is an advisory recommendation.  ANSI Z133 is an approved equipment label compliant with state, local, and federal laws.  It is the offical set of safety standards for safety equipment in the United States.  Personal protective equipment (PPE) should be snug fitting, include eye and head protection (helmet), leg protection (chaps), and no jewelry or loose clothing should be worn.  It should be noted that chaps are not required when climbing a tree.  Boots must be worn that are of an appropriate type for protection from chainsaws and for anyone who is operating a chainsaw.  Gloves are required for the handling of wire rope.  No gauntlet type gloves should be worn if chipping is to be done (gauntlet gloves are gloves with big cuffs).  

Good Communication through a job briefing
Good communication procedures should be in place.  Each job should begin with a job briefing.  A job briefing should summarize what is to be done, who will do each task, and potential hazards should be identified (risk management).  Also, the type of PPE that is needed should be determined, and the on-site supervisor should be responsible foe executing the entire plan.  Team work is essential, and there should be no questions about job responsibilities!  

Included with the job briefing should be the establishment of a drop zone, or a landing zone for falling tree branches and limbs.  This involves good communication between climbers in the tree and workers on the ground (figure 1).  

Figure 1:  Good communication should be established between tree climbers and ground workers, and a drop zone should be determined to ensure worker safety.  

A voice command and response system should be established, as well.  This ensures that warning signals are heard.  Hand signals can be used as well.   In summary, the purpose of a job briefing is to review any potential hazards, review the work plan, and to coordinate the activities of every worker.   

General Safety
All crew members must be trained in emergency response procedures.  In an aerial rescue, all climbers should be trained and capable of carrying out an aerial rescue.  As such, as second set of climbing gear should be available with a worker capable of climbing and performing a rescue.  All crew members should be familiar with the identification of poisonous plants (e.g. poison ivy) as well as dealing with stinging or biting insects (e.g. hornets).  Equipment must not be started or operated within 10 feet of the refueling area (this is an OSHA requirement).  

Electrical Hazards
All tree workers should have training and documentation of training to deal with electrical hazards,  It is wise to inspect electrical hazards before performing the work (you mean not after the work?  Huh??).  

Direct contact  is direct contact with an energized object (who would have thunk??). Indirect contact is contact with an object that is connected with an energized object (you don't say!).  It should be noted that footwear with electrical resistant soles or lineman's shoes are not considered protection from electrical hazards.  Rubber gloves are not considered proper protection, either.  Electric tools (except those with a self-contained power source) must never be used near electrical conductors.  

Chainsaw Safety
Chainsaw operation exhibits reactive forces such as a kickback, push or a pull (figure 2).  When cutting with the bottom of the bar, the chain has a tendency to pull.  This is known as kickback, and is one of the most common causes of injury.  Figure 3 shows the kickback quadrant, the area on the chainsaw bar that is prone to kicking back.  

Figure 2:  Reactive forces.  

Figure 3:  Kickback quadrant

Tree Felling and Removal
When felling and removing trees, a zone of danger should be determined where no workers should be present unless they are directly involved with the process (figure 4).  Also, an escape route with 45 degrees on either side should be established (figure 5).  

Figure 4:  Fell zone

Figure 5:  Escape route

Three types of felling notches are open face, conventional, and the Humbolt.  The depth of a tree trunk knotch should be 80% of the tree diameter.  See figure 6.  

Figure 6:  Hinge diameter information

A backcut with a conventional cut (45 degrees) is presented in figures 7 and 8, and an open-face notch with a 70 degree angle is shown in figure 9.  Figure 10 shows the opposite of a conventional cut, which is a Humbolt notch.  

Figure 7:  Conventional backcut

Conventional backcut with a more exposed apex.  

Figure 9:  Open-face notch

Figure 10:  Humbolt notch

Sometimes when cutting down a tree trunk, a very dangerous situation occur known as the barber chair (Figure 11).  Sometimes the butt of a tree can hit the worker causing serious injury.  

Figure 11:  The barber chair effect

To help prevent the barber chair effect, a felling wedge can be used (figure 12).  A felling wedge is a tapered piece of metal or plastic that wedges open a cut.  

Figure 12:  A felling wesdge

Chipper Safety
When using a wood chipper, no loose clothing or jewelry should be worn, and brush should be fed from the side of the machine.  The machine should be off with the key out and lock pin in place before someone gets into the blade area to perform maintenance (such as a clog).  The access panel should be closed, as well.