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Thread: Excavation Question

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    Excavation Question

    I've been lurking on here awhile, and have been quietly planning my pool build in North Central FL.

    This question is for those of you here in the southeast. In my backyard, there are plenty of longleaf pine trees. One of them happens to be right where my pool decking will eventually go. It is probably 50 ft tall, and 14'' in diameter. Obviously, this thing will be cut down. However, due to the very sandy soil, and longleaf's tendency to want to develop a trunk sized taproot all the way down to the water table, there is a possibility this thing may go 15-20 ft down.

    I am inclined to think that I should insist that this thing should be fully dug out, and removed from the earth as well as total removal of the shallow lateral root system. I imagine that a significant amount of earth will probably have to be added to the pit the tree currently occupies, and that a total packdown of the spot is necessary as well.

    Am I correct in my logic? I just don't want to get burnt here, as the tree is sitting where the terminal footer for the screen enclosure will go, and I obviously don't want settling issues/crackage of the footer if this situation isn't handled correctly. I have read widely varying reports on decompostion rates of longleaf taproots, so I am assuming that I don't want that thing left in the ground.

    I am also politely asking that those of you unsure/unknowledgeable of this soil type or root structure of longleaf pine please abstain from commenting if you are not certain on the right course of action to take. Thanks for your time.

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    Re: Excavation Question

    The roots will not go down 15-20 feet. I have removed 100 foot pines here by the dozens and the tap root doesn't extend past 5 feet.

    Dig up the tree and fill the hole with rock, not dirt, and you won't have any settling issues.
    Dave S.
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    Re: Excavation Question

    I'm not trying to contradict you or anything, but one time I attempted to dig out a pine taproot. I had the ground dug out 5ft below grade, and the thing wasn't getting any thinner around. I broke a strap when I tried pulling it out w/ my truck. I believe this may be due to the extremely sandy soil where I am at. By any chance, is the soil where you're at more clay based, Duraleigh? I'll definitely fill the hole w/ rock though, thanks.

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    Mod Squad zea3's Avatar
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    Re: Excavation Question

    Since your question is very specific and our forum has much less traffic this time of year you may not get the feedback you need in a timely manner. Your local county extension office may be the best source of information about soil and trees in your area. You could also contact a master arborist in your area about the root structure of the long leaf pine.

    I was able to find the Longleaf Alliance website which confirms your statement about the size and depth of the Longleaf pine taproot.
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    Re: Excavation Question

    The vast majority of what I have removed are loblolly pines rather than long leaf. Their growth characteristics seem close to identical with long leafs being a bit more slow growing with denser wood. Their appearance is pretty similar as well. I have probably cut down and dug the stumps out of around 40-50 that are at least 16" in diameter with some being 24.

    My soils is layered in that it is normally sandy down 3-6 feet and then can be either red clay or grey clay...very irregular.

    What I have experienced is the tap on even the biggest trees has never gone below about 5 feet. (there are sometimes some smaller (3-4" roots that go deeper but not often. The laterals may extend out many, many feet but I never see any lateral more than 6" in diameter much past about 8 feet from the trunk and that's unusual. By the time they get around 5 feet from the trunk, they are seldom, if ever more than about 4".

    From a practical standpoint, no one could ever hope to pull one of these large tree stumps with a pickup. I dig them up with a construction backhoe and the resultant dirt and weight of the trunk (I would guess around 2-3,000 lbs) is often more than my backhoe can lift and I have to "drag" them out of the hole and then carry them off using the front bucket.

    From an even more practical standpoint, you would need a track hoe to dig up anything much deeper than about 8 feet.....the backhoe becomes impractical past about 7 feet or so. The resultant hole if you have to go even that deep would me humongous.

    So, what I have taken away from my experience is that the tree will come up without digging too deep but, unless you clean out the hole and compact the disturbance as best you can, AND THEN FILL IT WITH ROCK, settling will occur.
    Dave S.
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    Re: Excavation Question

    This is what I was worried about... The depth of this thing going down to a point in which total removal will be extremely difficult... When I was talking to one of my prospective pool builders, he shared with me that one of the deepest taproots he had to fully remove because it was under where the pool shell would be went a full 16 ft down. The soil in my area really is sandy, which is what permits these trees to grow that far down. From what I have gleaned from the longleaf alliance, and other sites is that they will grow down until they hit either water, or some form of hardpan soil.

    Longleaf and loblolly have enough taproot structural differences, along with our differing soil structures that your experience, and mine are totally different, Duraleigh. I appreciate the comments, based upon your knowledge and experiences, I really respect your opinion.

    Ideally, I would want this thing fully removed, and repacked w/ gravel, as you suggested, Duraleigh. I am just concerned of a possibility that it may go down to a depth that the future pool builder may not have the equipment or desire to dedicate the resources to remove, and that he may attempt to persuade me that it will not be an issue of future settling from decomposition of taproot material when it is only removed to a certain depth of say 8-10 ft, while leaving another 8-10 ft in the earth.

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    Re: Excavation Question

    I guess you'll have to cross that bridge when you get there but I have no idea what a solution would be.
    Dave S.
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    Mod Squad Bama Rambler's Avatar
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    Re: Excavation Question

    I've seen them excavated in several different ways, from digging them up to bringing in a small drill unit and drilling holes all around the stump and pulling them out. For deep tap roots the boring machine works best as it creates less over dig and therefore less soil disturbment.
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    Re: Excavation Question

    What about soaking it in diesel and burning it in place...
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    Re: Excavation Question

    I too have heard of burning them, but was hesitant on discussing that... I have read differing accounts on burning them out. Some say they will easily burn all the way into the earth with a couple big holes drilled into them, and a daily soaking of diesel for a week or two before lighting. Theoretically, the trapped sap encased in the taproot will help the fire perpetuate completely down.

    Other sources claim that past a certain depth into the ground, the fire will run out of oxygen and die out. Considering I am desiring complete taproot material, I am at a bit of uncertainty here. Burning it out completely would minimize soil disturbance, and reduce the need for larger excavation than necessary. However, I do not want it to burn out half, or even three quarter way, with any of it left.

    I have one of these pine taproots in another spot in the yard, unrelated to where the pool will be. This is the one I had talked of earlier that I tried to rip out with a pickup. I cut it off around 4' below grade, and backfilled the hole. I have contemplated digging the hole back up, and experimenting with the burning method before cutting down the other longleaf pine in the future pool location, and having to deal with its taproot.

    On a brief aside, I have often wondered how many so-called "sinkholes" in FL were merely rotten taproots that were backfilled over, and foundations for houses were poured upon...

    Sorry for the long drawn out post. I have done a fair amount of research on this, and was hoping someone on here would know which taproot removal method works best in reality, as opposed to in theory.

    Bama Rambler, please better explain the drilling many holes and pulling out method. I am not aware of that one. I don't mind spending some extra money here on taproot removal to prevent future problems down the road.

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    Mod Squad Bama Rambler's Avatar
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    Re: Excavation Question

    It's pretty simple. They just bring a boring machine like a test well driller, and bore several holes around the stump as close to it as they can get to it, and then the stump, root and all will lift out of the hole with a backhoe or boom truck. It usually takes about 6 to 8 holes. If it's a very large tree, it may take more.
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    Re: Excavation Question

    I'll share some experience with sinkholes from MD. My parents had a wooded lot and at the time (20 years ago) it was legal to bury stumps here. That was done but they were not broken up well and compacted correctly. So about 10 years later holes started to develop. A sub-par mitigation job was done. 7 years later a very large hole developed. Easily 10' deep and big enough to swallow the lawn tractor, though the extent of the issue was much larger. So they brought in the big guns. The stumps were excavated, broken up finely and buried in lifts, compacted and layered with heavy duty fabric material. There were several layers of this done. The excavation was the size of a large residential swimming pool. About 8 dumps trucks of soil were brought in the make the hole complete (no material was moved offsite).

    The idea is that wood does not rot/deteriorate without oxygen. So by breaking up the stumps so they could be finely packed, there will no oxygen for them to use in the disintegration process. Again, I say the theory. In reality only time will tell. Except that I never will know because my parents are moving to a retirement community.

    The argument could be made for your situation that by disturbing the soil and packing it, that may not be any more "solid" than just leaving the tap root undisturbed (no oxygen) and building on top of it. However, it certainly wouldn't hurt to have thicker pool bottom concrete and perhaps some above code level of steel.

    Just a thought. I am not in the field.
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    Re: Excavation Question

    Thanks for your input, everyone. I will probably go with a full removal route, either by full excavation, or ideally by boring, and full pull out as suggested by Bama Rambler. I am hesitant to attempt burning, and definitely do not want to leave it in the Earth. The tree hasn't even been cut down yet. I will update as it gets closer to build time, and when I cut the tree down.

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    Re: Excavation Question

    Don't you watch AXMen , he pulls trees that were cut down supposedly over a 100 years ago that were lost in a hurricane and sunk on their own. They aren't perfect but they are about as good as fresh cut. They make some pretty wood once sawn. We have had brush piles burned and then buried, what didn't burn hasn't degraded much if any since being buried in clay soils. I have several hardwood stumps in my yard an old timer told me to take a 55 gallon steel drum with both ends cutout set it on top of the stump with a couple three bricks separating them then put old newspapers into the drum set the paper on fire and that it would burn the stump out. I have never tried it but keep thinking about it.
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