I am looking for opinions on a hazard tree definition and need help defining
imminent threat.

Here is the definition I am working with:

"Hazard tree is any tree with a combination of structural defect and or,
disease, and a proximity to persons or which property which makes it an
imminent threat"

The dictionary says imminent means: "about to happen, impending"

So for hazard trees that would mean a recent lean, crack, splits, or
hanging debris?

What do you think? What does imminent threat mean with trees? Is this too high standard?

Kevin Hillery
Whole Tree Works, Inc.

Reply to post by Kevin Hillery, on November 07, 1999 at 18:25:55:


The Balmville Tree in NY was recommended for removal by 5 out of 6 consultants in 1974. I assume it was hazardous and constituted an imminent danger.

In my web dictionary, I find:

Main Entry: im·mi·nent
Pronunciation: 'i-m&-n&nt
Function: adjective
Etymology: Latin imminent-, imminens, present participle of imminEre to project, threaten, from in- + -minEre (akin to Latin mont-,
mons mountain) -- more at MOUNT
Date: 1528
: ready to take place; especially : hanging threateningly over one's head
- im·mi·nent·ly adverb


Well, in 1994 it was worked on by volunteers to provide structural stability. Over the intervening 20 years, I guess no one told the tree what the definition of imminent was.

I'm not sure who needs to understand what imminent means; the tree or the guys pronouncing it hazardous?

You right. It's a prissy little sentence left open-ended by an amatuer author.


Bob W.

Reply to post by Wulkowicz, on November 07, 1999 at 18:25:55:

Bob, you made your opinion on the general issue pretty clear in the Liberty Tree thread. I have posted a number of times that IMHO we have overstated our ability to predict failure and may have set decision threshholds conservatively out of fear of liability or a misguided but sincere sense of responsibility or both.

But you're mixing up issues in your response here. The history with the Balmville tree has to do with cost/benefit decisons and an extensive system to stabilize the tree and mitigate the hazard.

That's different from whether it was a hazard (as then understood), imminent or remote, at the time of the pre-mitigation decision.

The particular definitions of "hazard," "reasonable," "imminent" and so forth may have less to do with textbooks and dictionaries than with applicable agreement, regulation or statute on a particular case or situation.

The terms of art, the philosophy and policy and the technical investigation of tree stability all need continuing work. But preaching about it does not necessarily help answer case specific questions.

Reply to post by Kevin Hillery, on November 07, 1999 at 18:25:55:

The simplest defiinition of "hazard" is risk of failure+target=hazard

Many factors go into the objective asssesmant of risk; speicies, habitat, structural defects and wounds, age, size, distace from butt to primary crotch (bifrication for those who dont like those words) and possible many others.

Targets can be houses, play areas, storage...

The HazEval is a way of giving a client a proffesional OPINION based on certain facts and maybe gut feeling.

Part of the eval is to give the client ways to mitigat the risk, since ALL trees have the potential for failure if the conditions are wrong. move the picnic table to the other side of the yard, crown clean, cable & brace, begin escrow for removal and monitor conditions on a set schedule (after the cabling and moving the picnic table).

Because of the highly objective nature of this procedure, I tell my clients that I recomend it to (I don't) get several from companies that wont be doing the work they recomend, ie on a purely colutative basis.

Reply to post by Kevin Hillery, on November 07, 1999 at 18:25:55:

Kevin; I do not use that term (imminent threat)personally, unless (I suppose) I advised people to move out to a motel until the tree was down.
I use "acceptable risk", and that is usually up to the client to decide. If I were asked whether some trees (bigleaf maples in Vancouver, for example) were imminent threats, I would would ask the poser of the question to define his or her meaning. Peter

Reply to post by Kevin Hillery, on November 07, 1999 at 18:25:55:

I rarely use the word HAZARD anymore. It shouts at you. I like what Peter said about risks. A trees that constitutes an acceptable risk for me may not be acceptable to the person who owns it, or vice versa. It has got to be a pretty scary tree to be unacceptable to the jack ass who shifts lanes on the beltway @ 90 MPH talking on the phone and drinking a beer at the same time... or to the moron who did a u turn on I 66 yesterday and caused an accident.
An ASCA speaker a few years back said the most common hazard associated with vegetation is blocked signs and critical views. I see more sharp branches sticking out into walkways than I see "hazard trees". What about trip hazards? If you plan to write a definition of hazard, either qualify it or make it as nearly all-inclusive as possible. We need to talk more about risk management and less about risk elimination.

Reply to post by Peter Torres, on November 07, 1999 at 18:25:55:

THat's the whole point here, I think. Define what you mean by 'imminent' Does that mean within a day? A week? A month? Just be careful of predictions.

Reply to post by Ed Milhous, on November 07, 1999 at 18:25:55:

Yes, acceptable risk is the right phrase to be using.
I am stuck in using this definition that the city has crafted and accepted. Under this definition of imminent threat, I am wondering if it means, "about to happen." If that is true then I should be using Visual Tree Assessment only to look for recent cracks, splits, leans, or hanging hazards and to suggest a monitoring program after a major storm and/or after the winter season.
Or is it my responsibility to conduct strength loss tests and root crowns where it is not an obvious problem and try and predict failure.

Kevin

Reply to post by Kevin Hillery, on November 10, 1999 at 08:59:04:

I think you have to put this all in the context of the City's policy structure, either existing if they have one, or what they are contemplating on implementing if in the planning stages.

If they have an inspection plan now, and it only includes a visual exam, you might want to limit it to that- the VTA concept. If they say they want a more detailed analysis, or a more refined assessment of each tree, that should be stated clearly. IOW, it isn't the term 'imminent threat' that is the problem, but rather defining to what extent the inspection will be done. If you are expected to predict failure with a higher level of certainty, you will have to do more testing and digging on each tree, at much greater expense.

The point is you want to be sure of what they are asking for. If they want an assurance that the tree won't fall over, you have to go a bit farther with the investigation. If they want a reasonable assessment that the risk is not great, the VTA may be sufficient, unless it shows other problems.

Reply to post by Kevin Hillery, on November 10, 1999 at 08:59:04:

Part of the context is still not clear to me. Are you a contractor asked to bid on "hazardous" trees but you need to identify them first? Are you a consultant asked for a price to assess "hazardous" tree but you have to figure out which ones they are? Are you a contractor or consultant asked to categprize trees according to their definition? Just what's going on may influence what you need to do.

In any case, after re-reading your initial question I'd say "imminent," or about to happen has to do with the liklihood of failure combined with a target. It does not have anything or not much anyway to do with how recently cracks or leans or other conditions have appeared. The conditions pre-disposing a tree to failure may have existed for 10 minutes or 10 years, but they exist now. If they do not introduce a high liklihood of failure I would not think the failure is imminent. The higher the risk of failure is the more likely it is that the failure is "imminent" or about to happen.

I'm not entirely familiar with VTA, but I would guess that visual assessment may reveal enough in some instances.... say the tree is half uprooted, the root plate moves visibly everytime a car goes by, the main crotch has split open and you can see daylight through it and it leans over a day care center... that "imminent" can but judged with no further investiagtion. In another case there's an open cavity that's visible, but further testing is required to assess strenght loss and risk of failure. More of a stepped progression than an either-or variable.

Reply to post by Russ Carlson, on November 09, 1999 at 22:53:17:

I thoroughly agree. I tell people who ask about these things, that the only thing that I will guarantee, is that every tree is guaranteed to fall over- someday soon.