Is the Air Spade the solution to home-builders' damage to tree roots in my community?

[Karen2]

How costly and how time-consuming would it be to Air Spade all around the sides and back of where a new home's foundation will be built, on terrain sloping fairly steeply either up or down from the street, in either medium-textured or clay soil? The trench should be sufficient to reveal the tree roots extending into the proposed excavation area from the adjacent forested areas, so that good decisions can be made about the trees.

This is in the Pacific Northwest. The trees of concern are mainly Douglas fir, Western redcedar, and bigleaf maple. I believe the evergreens, at least, are known to have wide-spreading shallow root systems. Not sure about the maples.

This community is an HOA, so has the legal power to enforce whatever good building practices it chooses.

 

[ATH]

An ounce of prevention is worth a pound of cure.

Don't allow the bad practices when the digging happens.

But yes, air excavation is a good tool for remediation.

 

[Raintree]

In my neck of the woods I charge $150/hr for man and equipment shop to shop, min is 4hrs. You never know whats underneath and how long it's going to take.

 

[Karen2]

In my neck of the woods I charge $150/hr for man and equipment shop to shop, min is 4hrs. You never know whats underneath and how long it's going to take.

What's the slowest progress you've ever made with an AirSpade, in terms of linear feet of trench per hour, and how deep was that trench? What do you think were the reasons for the slow progress?

 

[Del_]

This community is an HOA, so has the legal power to enforce whatever good building practices it chooses.

It seems that your goal is to have the HOA force every property owner to have air spading done before the location of the house is decided to preserve the trees?

Sounds like aggressive overreach of an HOA to me.

 

[Karen2]

It seems that your goal is to have the HOA force every property owner to have air spading done before the location of the house is decided to preserve the trees?

Sounds like aggressive overreach of an HOA to me.

I don't know how to accomplish my goal, but the goal is to stop "spec" home builders from selling new homes to unsuspecting families who then have big trees with severely damaged root systems fall on their new homes within a year or less. So far, nobody has been killed or injured that I know of, but one deck has been demolished. COVID has led to a building boom here (we are not a big city area), so there is not that much history from prior years.

I'm also wondering whether other new-home buyers have had tree failures that I know nothing about, since I only learned about the demolished deck because the homeowner submitted a request to have his neighbor cut down two trees and when I showed up to look, he told me what had happened.

Anyway, my secondary goal is to stop everyone in this HOA from causing problems for their downslope neighbors or for the HOA road system itself (we maintain our own roads) by cutting down the trees that absorb so much of our rainfall - at least not without building or expanding their existing stormwater retention systems to compensate for their deforestation activities.

 

[Raintree]

In virgin soil, thick fibrous root matts will slow the process down the most. Wet and rocky soils will also hinder the work.
A alternative policy is not build within the critical root zone of any tree. Hire an arborist before construction to advise and preserve your interests.

 

[Karen2]

In virgin soil, thick fibrous root matts will slow the process down the most. Wet and rocky soils will also hinder the work.
A alternative policy is not build within the critical root zone of any tree. Hire an arborist before construction to advise and preserve your interests.

Thanks! Unfortunately, the lots are small - 6500 sf is about average - and the homes now being built (especially the spec homes) are large. We allow the roof eaves to be 5 feet from the side and rear property lines, and a lot of the trees are now 24" DBH or greater (average age ~55).

My hope is that Air Spade excavation can allow for clean root cuts so the risk of disease is minimized, and also show which trees might be good to remove because too many of their roots will have to be cut. Because of the sloped terrain I think it is not obvious where the roots of a given tree go, and another possible influence is the fractured-sandstone bedrock, which in places is at or near the surface but in other places is much lower.

I think Air Spading would still be helpful even if we don't ask them to do the whole perimeter, but was just wondering what that most-expensive scenario would be likely to cost.

 

[ATH]

air spade will not replace removed roots. When you take away 75% of the tree's root system, even perfect soil for the rest is probably not enough.

If the area can be air-spaded after construction, why can't it be protected before and during? I just don't understand that. Yes, it takes extra planning and time, but if the neighborhood values that is the best option.

 

[Jed1124]

Critical root zone specifications can be done with math, no need for an air spade. Species, DBH, and height will determine how much space any particular trees root zone will require.
You would be better served to hire a consulting arborist who has some back round in establishing critical root zone specifications in construction sites.
Once specifications are established make sure there is a PHYSICAL barrier limiting construction equipment into the area specified. They will not respect some paint on the ground in most cases.

 

[ATH]

....
Once specifications are established make sure there is a PHYSICAL barrier limiting construction equipment into the area specified. They will not respect some paint on the ground in most cases.

I'll add to the physical barrier: stiff penalties in the contract for violating the barrier. Like $10K per day ... otherwise that orange construction fence is no better than paint.

 

[Karen2]

air spade will not replace removed roots. When you take away 75% of the tree's root system, even perfect soil for the rest is probably not enough.

If the area can be air-spaded after construction, why can't it be protected before and during? I just don't understand that. Yes, it takes extra planning and time, but if the neighborhood values that is the best option.

The idea is to air-spade BEFORE excavation by heavy equipment.
STEP 1: Air-spade a foot or two outside the proposed limits of foundation excavation, to see what's what.
STEP 2: Decide which if any trees will lose too many roots to be reasonably healthy AND structurally sound after construction. Recommend removal by owner.
STEP 3: Do clean cuts for remaining roots so disease will hopefully not invade root systems.
STEP 4: Excavate merrily away using heavy equipment in the proposed limits of foundation excavation.

A lot of the terrain here is steep. Trees that grow on steep terrain tend not to have symmetrical root systems. Especially for tree species that have far-ranging shallow root systems, the roots are small in diameter and work (to hold the tree up against wind and gravity forces) in tension but not in compression, so for stability the tree may send most or even all of its roots uphill rather than down.

 

[ATH]

My apologies...I misunderstood what you were asking. I thought you were looking at responding to soil damage (that you knew would happens but hasn't yet) by correcting with air excavation.

I don't think air excavation before construction is necessary or very beneficial. A simple soil probe can accomplish much the same. A good arborist with local experience and knowledge will understand how the species of trees involved respond to their growing environment as well as how they respond to disruptions. Have them set up root protection zones and then have the trees that cannot be protected removed ahead of construction.

I'm guessing there will be a lot more trees coming down ahead of construction, but that is better than people believing that they can keep a tree without adequate root zones and having that tree fail as you've outlined. It is hard to fit a big tree within a 10-15' space...

 

[Karen2]

The idea is to air-spade BEFORE excavation by heavy equipment.
STEP 1: Air-spade a foot or two outside the proposed limits of foundation excavation, to see what's what.
STEP 2: Decide which if any trees will lose too many roots to be reasonably healthy AND structurally sound after construction. Recommend removal by owner.
STEP 3: Do clean cuts for remaining roots so disease will hopefully not invade root systems.
STEP 4: Excavate merrily away using heavy equipment in the proposed limits of foundation excavation.

A lot of the terrain here is steep. Trees that grow on steep terrain tend not to have symmetrical root systems. Especially for tree species that have far-ranging shallow root systems, the roots are small in diameter and work (to hold the tree up against wind and gravity forces) in tension but not in compression, so for stability the tree may send most or even all of its roots uphill rather than down.

My apologies...I misunderstood what you were asking. I thought you were looking at responding to soil damage (that you knew would happens but hasn't yet) by correcting with air excavation.

I don't think air excavation before construction is necessary or very beneficial. A simple soil probe can accomplish much the same. A good arborist with local experience and knowledge will understand how the species of trees involved respond to their growing environment as well as how they respond to disruptions. Have them set up root protection zones and then have the trees that cannot be protected removed ahead of construction.

I'm guessing there will be a lot more trees coming down ahead of construction, but that is better than people believing that they can keep a tree without adequate root zones and having that tree fail as you've outlined. It is hard to fit a big tree within a 10-15' space...

Thanks, ATH! How do you recommend we get the roots of remaining trees to be cleanly cut? Was just reading how a large tree near Seattle had to be removed because disease had progressed into the bole from just one root that had been disturbed by trenching some years prior.

 

[ATH]

Don't cut roots that are too close to the trunk and large in diameter. There is an area (roughly equal to the circumference of the tree at chest height) that is called 'zone of rapid taper'. Outside of that most roots are pretty small in diameter. Not a hard fast rule, but a place to start.

 

[Del_]

The roots of the trees on the property of the already existing houses should also be air spaded for inspection to make sure that already damaged trees don't threaten the neighbors, their houses or their personal property. It is not only the roots of these trees that need inspecting, it is the whole tree. To be fair every existing tree in the HOA that is a possible threat needs inspecting by an arboricultural professional.

I bet you get some interesting feedback when the suggestion is published in the HOA newsletter.

If only the spec house builders are targeted it likely will be found to be discriminatory in court, and that is where this is going, IMO.

Overreach by an HOA.

 

[Karen2]

The roots of the trees on the property of the already existing houses should also be air spaded for inspection to make sure that already damaged trees don't threaten the neighbors, their houses or their personal property. It is not only the roots of these trees that need inspecting, it is the whole tree. To be fair every existing tree in the HOA that is a possible threat needs inspecting by an arboricultural professional.

I bet you get some interesting feedback when the suggestion is published in the HOA newsletter.

If only the spec house builders are targeted it likely will be found to be discriminatory in court, and that is where this is going, IMO.

Overreach by an HOA.

Hi Del_, no chip on your shoulder at all, eh? Of course all non-minor excavation projects (generally new homes and additions) would be subject to the same requirements. I think you confuse my observation that problems seem to follow a certain kind of homebuilder with an intention to enforce rules against only some builders and not others.

And P.S. - HOAs can be quite arbitrary in their enforcement of rules without much risk of losing lawsuits, that's what's so infuriating about them for many people. To move in, you give up a lot of rights.

About the already damaged trees on neighboring properties you mention, that's only rarely an issue. The HOA was established in the early 1970s, and now has about 500 undeveloped lots scattered among 2600 already-developed lots with greenbelts also spread throughout. For the most part, you won't find new homes being built right next to other homes that were recently built. Somewhat often they are adjacent to challenging empty lots that were bought by the HOA mostly from tax sales in the 1990s, and put into open space. The non-open-space lots now being developed often are also scary steep and should have been open space, IMHO, but I'm not in charge of that.

And yes, any tree that is in failing health without any help from excavation equipment should be removed if it is a danger. But those are not very common here. The HOA had an arboriculture company do a Forest Management Plan for us in 2015 that said we have a healthy forest, so it's not just my opinion.

 

[Del_]

And yes, any tree that is in failing health without any help from excavation equipment should be removed if it is a danger. But those are not very common here. The HOA had an arboriculture company do a Forest Management Plan for us in 2015 that said we have a healthy forest, so it's not just my opinion.

It takes years, sometimes decades for the damage to trees from excavation equipment to become a serious problem. How do you know that this type of damage is not 'very common here'?

Your agenda seems to be more about the financial punishment of owners and builders of new houses while giving a big pass to existing homeowners. This would be a boon to existing homeowners because their properties are worth more when less densely populated. It also screws over the owners of empty lots who the HOA would be forcing to play by different rules than the owners of existing properties.

If your development isn't suffering from root zone construction damage and damage to existing trees from changed drainage patterns, then it is a most unique development.

Your 'Forest Management Plan' likely doesn't have much to say about the trees near existing houses and the damage they may have suffered during construction.

You ought to quote parts of the plan that you believe pertains to the forest that is up against houses. It would be educational for us all.

 

[GeeVee]

No, an air spade is not a good way to assert your will. Why destabilize the ground with an air spade, when non destructive methods are available? I suspect you already got answers, but they don't suit your desire, so now you are answer shopping.

Is it your house? Are you secretly buying up lots and having your brother in law build spec houses? NIMBY much?

"I want a miniature fifedom here where I live, and when its gets hosed up and complicated- I'll use the civil route and sue you....." Said every HOA board member every where, since the beginning of time.......

 

[Karen2]

It takes years, sometimes decades for the damage to trees from excavation equipment to become a serious problem. How do you know that this type of damage is not 'very common here'?

Your agenda seems to be more about the financial punishment of owners and builders of new houses while giving a big pass to existing homeowners. This would be a boon to existing homeowners because their properties are worth more when less densely populated. It also screws over the owners of empty lots who the HOA would be forcing to play by different rules than the owners of existing properties.

If your development isn't suffering from root zone construction damage and damage to existing trees from changed drainage patterns, then it is a most unique development.

Your 'Forest Management Plan' likely doesn't have much to say about the trees near existing houses and the damage they may have suffered during construction.

You ought to quote parts of the plan that you believe pertains to the forest that is up against houses. It would be educational for us all.

Hi Del, was busy and didn't notice this until just now...

I guess I don't know for sure whether my community is riddled with trees that are dangerous due to decades-old construction damage, but our owners of existing homes have to apply for permission to remove their trees, and if this were a widespread problem I would have thought we'd be getting more applications to cut down sick and/or dead trees than we are. And/or that we'd be seeing more dead and unhealthy-looking trees just driving around in the community (I'm aware that just because the owners are supposed to apply doesn't mean they all do).

It's possible that there were more young trees and fewer old ones when the first homes began being built in the 1970s. I do know that the first homes to be built were the smallest, and gradually ever since then new homes have been getting bigger and bigger, so maybe those older homes just did not disturb as many tree roots as the newer ones do.

As an aside, it's pretty amazing how some of those older homes have really big firs and/or cedars growing less than 10 feet from the home, sometimes with only a couple of feet between the trunk and the roof eave, yet that huge tree looks in rude good health, the home appears to be undamaged (including the foundation), and the owners love their tree.

The Forest Management Plan (https://suddenvalley.com/wp-content/uploads/SVCA-Forest-Management-Plan-2015.pdf) was supposed to evaluate only community-owned trees. The report writers said they did their best but had a lot of trouble figuring out which trees WERE community-owned and which were not. There are mostly-narrow greenbelts separating rows of lots throughout, plus a significant number of lots scattered around the community have been repurchased by the HOA (mostly during a 1990s sewer moratorium) and placed into open space.

You mention damage to existing trees from changed drainage patterns. I have been wondering about that for some time. Tracking down the reasons for a suddenly-soggy yard is beyond the ability of most ordinary homeowners once a leaky water line is eliminated from contention, and nobody in the HOA management has been attempting anything like that. There is anecdotal evidence on Nextdoor that some wooded areas have become soggy that were not soggy a few years ago, with the poster blaming new construction that happened on a lot uphill from there, but who knows.

Since you keep bringing it up, my motivations are as follows:
The community maintains its own roads and system of ditches and culverts, and knows relatively little about that system's capacity and weak spots. Initially, my top priority was to protect that drainage system from failure, i.e. prevent flooding and/or roadway undermining by stormwater flows. I am a civil engineer. Runoff coefficients are what we learned in school, and the lowest are for forested land.
However, my participation on the ACC brought to my attention the fact that some of the homebuilders in this community have been extremely careless about how they treat tree roots, culminating in at least one instance of a (clearly root-damaged) tree falling on and demolishing the deck on a new home just months after the current owner had purchased it from the builder. So now preventing hazard trees has taken over my top spot, which is painful because it has me asking the builders to remove trees that their plans indicate will remain.