Sidewalk vs trees advice

[S Mc]

We were approached by the Public Works Director of our city about a situation with some trees which have overgrown the sidewalk. As we have been very vocal in requesting them to research before simply cutting into major roots and buttress flairs, I appreciate the fact that they are even trying to find a resolution to this dilemma.

These two trees are silver maples (Acer saccharinum, probably in the 90 to 100 yr old category. They have grown over the sidewalk, particularly the south tree.

His question:

Can they remove the sidewalk from under the buttress flair? or

If they cut off the sidewalk outside the buttress flair (leaving a section of old sidewalk intact under the buttress flair), should they:

a) Pour the new sidewalk right up against the old that is left under the flair?

b) Leave a space of dirt between what is left and the new sidewalk (which would then curve out and away from the tree?

I would like to know what you all think and your options. Have any of you experienced this scenario?

Thanks! Sylvia

 

[oldirty]

cant offer advice but that first pic is cool. looks like its melting onto the concrete.

 

[Nailsbeats]

I don't have any experience with this scenario, but I would guess you could pull that piece of the sidewalk and throw some good soil with mulch down and rerout around it. Otherwise cut it down and make firewood, price is good this year.

 

[treeseer]

all that is needed is to use $5 worth of asphalt to ramp where there is a tripping hazard. Why do anything else? so what if the concrete moved a little--the public is not harmed or even inconvenienced by this.

any of the proposals you mention will do major damage to the trees, either by wounding or loss of support or both. If i were working for the owner, I would fire off a certified letter to the town attorney notifying her of the $$$$$$$$$$$$ value of the trees, and our willingness to recover that value should the trees decline as a result of this needless work.

attached tale refers to a town's insurance company paying out millions for hacking roots just because they wanted a perfectly linear pavement.

Sylvia if you want a ppt on this i can snail you one if you pm me your address. ps the book costs all of $20...isa really rips us off with these book prices huh?

SIDEWALK STRATEGIES


Reducing Infrastructure Damage by Tree Roots: A Compendium of Strategies was recently released by the International Society of Arboriculture. It was authored by University of California Cooperative Extension’s Larry Costello, who also wrote last year’s excellent Abiotic Disorders of Landscape Plants. Many strategies for resolving conflicts between mature trees and sidewalks, creatively merging the green infrastructure with the gray, are detailed in this book. In order of impact they are:

1. Remove old panels. Install a new sidewalk of packed stone, asphalt, pervious concrete or concrete curved away from buttress roots. (If concrete, reinforce with fiberglass rebar, wire mesh, or standard rebar)
2. Remove old panels. Bridge buttress roots with packed structural soil and sand under fabric. Install sections of recycled rubber, asphalt, bricks, pavers, pervious concrete or concrete above.
3. Leave heaved sidewalk in place and make the surface smoother by either
grinding down the lifted edges, making asphalt or concrete wedges or ramps, or both.
4. Remove old panels, prune roots, and install new panels at original grade.
This last option is still commonly done in North Carolina, with predictable results. Several historic trees in one town died soon after having major roots pruned. One root-pruned maple tree in another town toppled over and crushed a vehicle and its driver. It is clear that this treatment often shortens the safe useful life of trees. It’s time to find a better way.

Strategies #1-3 are ADA-compliant and often cost little more than #4. If you factor in tree removal and replacement expense, not to mention liability exposure, they cost far less. Specific engineering details and case studies are clearly presented, along with a list of material suppliers. Reducing Infrastructure Damage by Tree Roots is a goal we can all agree on, so this book is an important new tool for urban foresters. You can order it via www.isa-arbor.com or call 217-355-9411.

The book’s author spoke at the annual meeting of the American Society of Consulting Arborists earlier this month. He told us that he is planning a second edition, and looking for input. Anyone who has experience with these issues is encouraged to pass it along, for possible addition to the next edition.

Guy Meilleur
Better Tree Care
[email protected]

 

[(WLL)]

:agree2: the side-walk can be repaired without touching the tree

 

[jomoco]

all that is needed is to use $5 worth of asphalt to ramp where there is a tripping hazard. Why do anything else? so what if the concrete moved a little--the public is not harmed or even inconvenienced by this.

any of the proposals you mention will do major damage to the trees, either by wounding or loss of support or both. If i were working for the owner, I would fire off a certified letter to the town attorney notifying her of the $$$$$$$$$$$$ value of the trees, and our willingness to recover that value should the trees decline as a result of this needless work.

attached tale refers to a town's insurance company paying out millions for hacking roots just because they wanted a perfectly linear pavement.

Sylvia if you want a ppt on this i can snail you one if you pm me your address. ps the book costs all of $20...isa really rips us off with these book prices huh?

SIDEWALK STRATEGIES


Reducing Infrastructure Damage by Tree Roots: A Compendium of Strategies was recently released by the International Society of Arboriculture. It was authored by University of California Cooperative Extension’s Larry Costello, who also wrote last year’s excellent Abiotic Disorders of Landscape Plants. Many strategies for resolving conflicts between mature trees and sidewalks, creatively merging the green infrastructure with the gray, are detailed in this book. In order of impact they are:

1. Remove old panels. Install a new sidewalk of packed stone, asphalt, pervious concrete or concrete curved away from buttress roots. (If concrete, reinforce with fiberglass rebar, wire mesh, or standard rebar)
2. Remove old panels. Bridge buttress roots with packed structural soil and sand under fabric. Install sections of recycled rubber, asphalt, bricks, pavers, pervious concrete or concrete above.
3. Leave heaved sidewalk in place and make the surface smoother by either
grinding down the lifted edges, making asphalt or concrete wedges or ramps, or both.
4. Remove old panels, prune roots, and install new panels at original grade.
This last option is still commonly done in North Carolina, with predictable results. Several historic trees in one town died soon after having major roots pruned. One root-pruned maple tree in another town toppled over and crushed a vehicle and its driver. It is clear that this treatment often shortens the safe useful life of trees. It’s time to find a better way.

Strategies #1-3 are ADA-compliant and often cost little more than #4. If you factor in tree removal and replacement expense, not to mention liability exposure, they cost far less. Specific engineering details and case studies are clearly presented, along with a list of material suppliers. Reducing Infrastructure Damage by Tree Roots is a goal we can all agree on, so this book is an important new tool for urban foresters. You can order it via www.isa-arbor.com or call 217-355-9411.

The book’s author spoke at the annual meeting of the American Society of Consulting Arborists earlier this month. He told us that he is planning a second edition, and looking for input. Anyone who has experience with these issues is encouraged to pass it along, for possible addition to the next edition.

Guy Meilleur
Better Tree Care
[email protected]

Excellent reply Treeseer, I would only add that there is a new rubberized sidewalk available that will bend to go with the flow, skate boarders and trick bicyclist love them as launch pads.

jomoco

 

[memetic]

I've never had to deal with anything like this, but what I have SEEN is the sidewalk routed around the tree(s). Mostly I've seen the sidewalk formed circular around the base and square on the other sides.

Those pictures are great. I have seen a lot of trees heave the sidewalk (up), but I don't know if anyone else noticed how the trees actually pushed the walk OUT at least 2-3 inches instead of up, then out.

 

[S Mc]

Thanks Guy. I was hoping you would chime in here. The book you referenced is the one I purchased last year and took into the Public Works Dept and insisted they read. They have since purchased the book themselves.

The problem here is that the City Council reneged on a decision to hire a City Arborist and no one knows a thing about trees there. To his credit the PD Director learned from the mistakes made last year and has been trying to ask before they go ahead.

His idea is to cut the panel of concrete (that is under the flair), leave the concrete under the flair and repour the new sidewalk out from there. (We were against the idea of pulling the concrete out from under the tree and the subsequent damage that could/would entail.) His hopes are that with leaving the concrete under the tree and repouring it (going out into the boulevard in order to achieve ADA compliant width), that structurally this would disturb the tree the least amount.

Since this is out of our area of expertise and experience I posted this question here.

To tell you the truth I have no idea why they are focusing on this portion of sidewalk when there are so many worse areas in town. However, we are not part of the decision making process and, in fact, have not been hired by the home owner nor the City. But after ranting at them for months last year, I cannot just tell them to find out for themselves and want to encourage them in trying to do their job with more fore thought. And I applaud his efforts to look at the situation without automatically demanding that the trees be removed.


Sylvia

 

[memetic]

Just do this:

edit: or whatever your city/town uses for ADA width.

 

[treeseer]

Just do this:

edit: or whatever your city/town uses for ADA width.

Good idea, tho that sidewalk already looks compliant. it could be widened by digging out turf and packing gravel outside the concrete, or adding concrete as memetic suggests.

cutting the concrete near the tree would 1. move the concrete under the tree and probably damage it, and 2. Definitely destabilize it, as the tree is now resting on that panel. Why would the town want to expose itself to liability by destabilizing the tree?

 

[S Mc]

Good idea, tho that sidewalk already looks compliant. it could be widened by digging out turf and packing gravel outside the concrete, or adding concrete as memetic suggests.

cutting the concrete near the tree would 1. move the concrete under the tree and probably damage it, and 2. Definitely destabilize it, as the tree is now resting on that panel. Why would the town want to expose itself to liability by destabilizing the tree?

Highlighting your "definitely destablize"... this is exactly what we were concerned about even if they try to leave the cut portion under the tree.

Thanks, Memetic. Your drawing is actually what the PW director was hoping to achieve.

Sylvia

 

[BC WetCoast]

Good idea, tho that sidewalk already looks compliant. it could be widened by digging out turf and packing gravel outside the concrete, or adding concrete as memetic suggests.

cutting the concrete near the tree would 1. move the concrete under the tree and probably damage it, and 2. Definitely destabilize it, as the tree is now resting on that panel. Why would the town want to expose itself to liability by destabilizing the tree?

I really don't think removing that concrete from under the root flare would destabilize the tree. The tree's stability is in its roots which are under the sidewalk. And as anyone who has broken a sidewalk with the outriggers from a boom truck, concrete sidewalks are not strong in any bending pressure. Which this would have to be for it to support the tree.

I don't think hammering out the sidewalk is going to affect the tree at all. You may scar it pulling the pieces out from the flare, but that is all.

My solution would be to break up the sidewalk for about 10' on each side of the tree. Use an airspade and blow out a bunch of the soil where the new sidewalk will be and use a structural soil for the sidewalk base. I don't think it matters whether you arc around the tree or ramp/bridge over. The sturctural soil will reduce the compaction load around the roots and allow better air exchange in the soil pores.

They may also want to consider some vertical mulching.

It would be very interesting to dissect the wood growing over the sidewalk and see if the xylem tissue is actually part of the pathway from the roots to the shoots or whether the tree bypasses that part of xylem.

 

[2FatGuys]

Good idea, tho that sidewalk already looks compliant...

Be careful judging compliance with the ADA. The ADA is civil legislation, tested in court, not enforceable via building codes. Most states have adopted some form of accessibility guidelines and codes to try to enforce accessibility issues, but few have been approved by the Department of Justice as "compliant". Montana, like many states, has adopted ANSI 117.1 as their accessibility standard. ASNI 117.1 does allow for a 36" wide "accessible route", however it also addresses surface uniformity, tactile surfaces, and other issues that surround this situation. As it exists, the current tree situation meets most all states' definition of "tripping hazard". The solution to that specific issue could be as simple as pouring a 4" high curb along the tree side of the sidewalk to act as a guide for canes, assuming there is still adequate width remaining on the walk, if the "change in height" between heaved panels is no more than 1/2". However, that would be a very short sighted solution since we all know that the tree will continue to grow and shift the concrete. The only long term solutions are those that remove the sidewalk from movement influence by the tree. This would require relocating it in such a way as to provide adequate growth room before impacting the sidewalk again.

Treeseer: Where are you in Wake County? I was at Preston Woods on Saturday...

 

[treeseer]

The only long term solutions are those that remove the sidewalk from movement influence by the tree.

Why? the movement is so slight and gradual it can just stay imo. true, the roots are a tripping hazard; was not thinking of blind folk.

I'm near Apex. preston woods is nice enough but not many trees left. my kids play soccer there.

Sylvia, maybe you could point them to other less compliant sidewalks so they leave this well enough one alone...?

o and what does the taxpayer/tree owner think of all this?

 

[2FatGuys]

Why? the movement is so slight and gradual it can just stay imo. true, the roots are a tripping hazard; was not thinking of blind folk.

The A.D.A. applies to ALL disabilities. The movement of the sidewalk, however slight, creates uneven surfaces that become tripping hazards.

I'm near Apex. preston woods is nice enough but not many trees left. my kids play soccer there.

I was in Apex also. My brother lives in a fairly new (read that as TREELESS) subdivision of HUGE houses on TINY lots right off Apex Peakway...

 

[RUBE]

Before fighting about the outside Id check the insides for rot at or below the root flare. Seeing as its a soft maple Id also look up for bad unions or cavities as well. Ive seen many of these that have very little sound wood from root rot that creeps up the trunk, on the inside, from past damage.

 

[S Mc]

I really appreciate everyone's feedback. I am passing this all on to the PW Director. From past chats, the ADA compliance mandate they are being told to allow is 48".

I have no leverage here as far as whether or not they address this section of sidewalk; only the courtesy the PW Dir has extended in asking our opinion.

I am constantly amazed at the public in how ill informed they are and/or how reluctant they are to get involved. Many are willing to gripe behind their hands but few will come to the meetings or address the issues publicly. So this translated in little ole' me, all by myself, going to meeting after meeting with speech after speech to enlighten the City Council and the Public Works Dept on the benefits of trees in our community and how we shouldn't just get rid of them and plant new ones (if any) because they have become inconvenient.

Many of our old, majestic trees were planted in the late 1800s/early 1900s before sidewalks and paved roads were an issue. Yes, they are becoming a problem now but we need to work around that as best as possible in this their final years. Those "final" years may very well out live us.

I was asked to put together a street tree species list for the City that would ensure that they NEVER have this issue (the sidewalk conflicts) to deal with EVER again. I flat out told them that was unrealistic and impossible. What other system within the City is expected to last FOREVER with NO maintenance?? How unfair to demand that of our trees!

So I have received many "well saids" from people who read my letters to the editors and did see me at the council meetings but unfortunately, the people the City Council will listen to are the ones who have threatened to sue the city over tripping on the sidewalk. The squeaky wheel.

As I have said though, I am very pleased that the Pub Works Director took the problems we had last year to heart and has tried to find a more judicious way of handling the sidewalk/tree issue. One of the last committee meetings I attended was a real eye opener for me. The PW Dir had a list of projects that he was being grilled on; their progress; their outcome; their scheduling. All of these issues were very important to the functioning of the city and its citizens.

Until the City Council commits to hiring a City Arborist who can take over the duties of maintaining our small but important urban forest, the trees will continue to have to take a back seat. That is the unfortunate truth.

Which means that people like David and I will continue to bring these issues to their attention until that is achieved.

Sylvia

 

[treeseer]

ensure that they NEVER have this issue (the sidewalk conflicts) to deal with EVER again. I flat out told them that was unrealistic and impossible. What other system within the City is expected to last FOREVER with NO maintenance?? How unfair to demand that of our trees!

Say on, Sister!

 

[treemandan]

I would be more worried about the 30 pound raccoons living in it or moreso the actuall canopy.

I can't fore-go my enthusiasm to chop down some piece of crap tree that could cause a problem and I can't condemn a city interested in in dwellers safety. Most of the time the city runs the budget down and neglect sets in, its expensive.
One of the many things that has me so rampant to hack down trees is thier ease of replanting. It this wasn't possible I wouldn't chop down too many trees.
I don't seem to be afraid to advise that " what goes up is gonna come down " but I do hesitate when its a PROMINENT TREE.
I guess MY definition of that is: A seemingly healty tree of the suited species growing suitibly in a suitable spot.
I grew up in a place where large street tree root flares made for awesome bike ramps because the guys who worked for the town always plastered up the cracked sidewalks. Someplaces were tricky for some people to navigate by foot.
Urban renewal? Think like that sometimes if the issue is getting out of hand. I tell people to buy trees all the time. I also tell them " I wouldn't let THAT stand around to much longer " I am not especially reffering to the silver maple in question but sometimes getting a sooner start on a replanting or at least planning for it may be good.

 

[treemandan]

Say on, Sister!

Yes you girls sound like tough smartasses. I guess the best that could be done is a basic list of the proper species written up in writing and maybe a estimated cost of upkeep. Doesn't sound that hard.Its the money that's going to be tough.