Tree stump under concrete

[Deltarat]

I am planning a new shop. Due to the set back from the power lines, it is going to put 4 tree stumps right in front of my door. There are 4 pines trees in a cluster that are from 24-36 inches in diameter and form about a 10-12 foot diameter circle. They will fall about 5' in front of my roll up door. When I cut the trees I am going to have the stumps ground as low as possible.
What else do I need to do in prep for the concrete and what additions do I need to do to the concrete to be sure it will not sink in the future?

 

[RoscoeJ]

The stump will eventually make a sink hole ,though may take awhile,it may speed it up if your parking there. I had a stump on the right side of my stone driveway,its a sink hole now ,when I parked it there . I dont use the side often. I just keep fillig it with the stones. I would pull the stump and fill with stone,or burn it out.

 

[boiler7904]

Pull the stump and as much other organic material from the hole as possible. It will all decompose with time. As it does, your foundation and slab(s) will sink. It's not a question of if it will fail. The question is how soon and at what cost.

After all of the organic material is out, fill the hole with stone or fill dirt and compact it in lifts of 6 to 8" as you go.

 

[kcombs]

My house is in an old walnut orchard and I have had walnut trees removed with a backhoe, it takes about two minutes to a tree. If I were you, I would fill the hole with gravel and not backfill with the original dirt. You really need to talk to someone who is a local expert on the correct material to use(such as road-base) and how to compact it so you don't have a sinkhole in a couple of years. Just my two cents worth.

 

[Northstar9126]

A couple of hundred bucks to have the stumps dug out is going to seem like a real bargain when you have problems with your concrete down the road.

 

[aarcuda]

we cut the trees and leave a big ol stump and then rip it out of the ground with a backhoe. or just use the backhoe to knock the tree down and rip out the stump at the same time

 

[Deltarat]

I thought of the backhoe, but I figured a 36" tree would probably need a trackhoe to do the job. The 4 trees almost touch at the bottom, so it is like having a 12' diameter stump.

 

[ron in sc]

I had a bunch of trees and tree roots from trees that have gone down in hurricanes in the area of my garage too. We dug all the roots up with a
Cat Multi Terrain Loaders, it was pretty good size, it weighted about 10,000 lbs.

 

[Lloydthumper]

I thought of the backhoe, but I figured a 36" tree would probably need a trackhoe to do the job. The 4 trees almost touch at the bottom, so it is like having a 12' diameter stump.

Not with Pine trees a back hoe can do it just keep in mind you will need a good bit of dirt or crush and run to fill the hole in I would also rent a tamper and fill it in in layers as much as possible and tamp it very good to reduce the settling I would also dig out enough to hit good soil in the whole area to also reduce the settling.

 

[PAToyota]

Easiest way to have settlement problems in the future is to leave organic matter and cover over it. Strip out any stumps, tree roots, topsoil, brush, and such down to the base material and start from there.

 

[Hurricane]

ive knocked over trees 4ft arond or bigger with a backhoe.push as high on the tree as you can without breaking it. DO NOT break the tree when pushing over, it makes for a lot more work getting the stump out. if the tractor wont push it over, dig around the tree and push again, it will do it. the fastest way to clear is to push the whole tree over, stump and all, then do your cutting while its laying on the ground. whoever does the dirt work for your building pad will be able to knock them over no problem.


you can use dirt to backfill the hole, but if it was me, id scoop out all the disturbed soil and backfill with rock. if you use clean rock (more expensive) then theres no compaction needed. crushed stone is cheaper but youll have to compact
________
buy marijuana seeds

 

[Steve in Mi]

Another vote for removing the stumps.
I removed all stumps where I planted my shop but those stumps I buried in the surrounding area started to show up as sink holes some 20 years later. I am still adding soil and re-seeding spots in my yard where once upon a time a stump was left to rot. When will it stop

 

[alkemyst]

Grinding is the wrong way to take care of a stump really. It works for people only living at a place a few years prior to moving, making it the next guy's problem.

It used to be grinding was cheap as hell, but now that it's become popular it's in the three figure range now and pretty close to having a backhoe come out anyway or even the cost of a rental.

If you are going to pour concrete over it, it's going to be a disaster down the line.

One of the ways you can save some money is ask your neighbors if they have stumps they want done (or holes dug) contract the guy to do all of you...gives him more of a full day with hardly any down-time due to travel.

I was going to have this done, but when I got the pricing back I figured my time here and there on a few weekends would be better. I ended up digging a hole about 8' across and about 5' deep. I was able to break up the stump and get it out of the hole. Fortunately this part of the property was already high. Once all was said and done it only needed a top layer of fill to grade it right.

 

[Kevin54]

If you cut the trees DO NOT cut them to the ground. It makes too hard of work for someone to dig them out. Leave them up three foot or so. they can use the tree stem for leverage to push / pull and to see exactly where it is at. Someone good with a 'hoe can have all of them out in no time. Most will dig around, and use the stem to push it over, then slap a chain around it, raise it up and drop it a few times to give you some dirt back. Look at how many fence rows are taken out every year. If you gring them down and pave or concrete over them, in a couple of years you will have that 'hoe in there anyhow, only it will cost probably 3-4 times as much by the time the concrete is busted up and fill hauled in. Not counting what new concrete will cost by then.

 

[Deltarat]

I have sold the trees to some loggers. They will come get them, haul them off and clean up the mess, not counting the stumps for $500. I had a logger in another part of the state say that I should make some money off them due to the size, but there aren't many loggers in this part of the state. I don't know how low they will cut them.
It seems like my Bronco restoration, the deeper I go, the more I find wrong.

 

[6768rogues]

I agree that the stump should go. My son came over with his backhoe and ripped out a pine stump over 2 feet in diameter in short order. Pine stumps usually come out easy.

 

[Deltarat]

Should I do anything special with the concrete other than maybe a lot of rebar?

 

[banzaitoyota]

Spend your money on proper preperation of the site.

 

[Hurricane]

the only other thing i can think of is when you prepare the site, after you strip the topsoil off is to run a root rake through there to pull out as many roots as you can
________
smoking kills

 

[ron in sc]

Spend your money on proper preperation of the site.

Definately


I had a geotek study in an effort to avoid any settling problems. I followed all recommendation so hopefully I will avoid any significant problems.

 

[Z07coupe]

You have received a lot of good advice here. But I would suggest re-filling the hole with 4" minus or shot rock with a high percentage of fines. Compact the rock as the hole is filling up. Clean rock or shot rock will leave many voids, just what you don't want.
This next item may be dreaming, and I would like to hear other thoughts. Would it be worth it to run a 4" pvc pipe under your base rock and end in the middle of the former hole(s). Then pour the concrete. Later on, this would give you an access point for introducing a mudjacking slurry (with portland mix), should you ever detect settling. Maybe that's over engineering the project.? But it would only cost a few dollars to install.

 

[Junkman]

Dig the stump out, and fill the hole with stone and stone dust. Once that compacts, it is as strong as concrete itself. The one thing that I have learned over the past 50 years, is that the best compaction is nature. After you dig out the stump, let the ground settle over one winter, and then do your concrete work. If not, no amount of rebar is going to keep the concrete from cracking. Rebar only keeps the cracks from opening up. A few years ago, I was involved in the "restoration" of a large department store that the floor had failed. When we cut open a section of floor, we could clearly see that the ground under the concrete had sunk about 3 feet because the trees that were cut flat with the ground had rotted away. The entire store had to be emptied of all merchandise and shelving, and a hole cut into the side of the building. Then we brought in jack hammers to remove one half of the floor. Once all that was put to one side, then the excavators came in and dug down 15' to remove all organic material. All the excavated material had to be trucked away, and clean organic free material was brought in and compacted in 6" increments until it was brought back to grade. I was told that the total cost was over a million dollars when finished. Now, there is a super market on the site, since the department store moved to another location. When it comes to construction, there are no short cuts that are successful over the long term. Do it right the first time, or keep repairing the shoddy work for years to come.

 

[wrigh003]

Do it right the first time, or keep repairing the shoddy work for years to come.

Words to live by.

 

[Lravey]

You are getting good advice here!! I have had personal experience with the problems associated with concrete slabs poured over pine stumps. I "inherited" this issue when a previous owner had stumps ground, then built a building on top. 12 years later, I had to completely demo the 40x60 building. The damage was so bad that the building started to collapse!!

Pine stumps have a single "tap" root that grows straight down. Trees the size you describe can have a tap root 5 to 6 feet deep. They are actually pretty easy to get out with a backhoe. You dig down to the bottom of the tap root half way around the stump. You can then push the stump over and pull it out with the backhoe. When you refill the hole you MUST compact the soil evey 6 to 8". Good Luck and keep us informed of your progress.

 

[duke182]

yyou recieved a lot of good advice. i have only one thing to add.
you might want to check with your local concrete supplier and ask about fiber reinforced concrete. a little higher inprice but well worth the investment.

 

[banzaitoyota]

We have a situation at work. New "temp" office complex installed:
Think a 44 section "double wide"

Contractor came in, removed the trees and grummed the site. Brought in fill, compacted, added base of crush and run. Paved the parking lot. That was November.
He already has had to return to to fix 2 BIG sinkholes. and I discovered a new one today.

 

[Kevin54]

This next item may be dreaming, and I would like to hear other thoughts. Would it be worth it to run a 4" pvc pipe under your base rock and end in the middle of the former hole(s). Then pour the concrete. Later on, this would give you an access point for introducing a mudjacking slurry (with portland mix), should you ever detect settling. Maybe that's over engineering the project.? But it would only cost a few dollars to install.

Not a bad idea at all.

 

[Deltarat]

It all sounds like good advise, but I live in backwoods Ms.Delta. We are 50 miles from any rock and then all we can get is washed or clay gravel or slag- the grey rock that they put on the roads. I don't think you could find crushed stone or stone dust in the state of Ms. The gray rock lays pretty close so it may be my best bet.
After hearing your advise, I am going to make sure my shop is not over the stumps. If I have to tear up the concrete later, at least it will not be under my shop.
If anyone has any other comments, I am open to all suggestions.

 

[scottyag02]

A very good thread here, as I am in the exact predicament right now. I posted a couple weeks back on this, but a few more details this time;

I removed 9 large stumps where my shop will be built. I am just southwest of Houston and the soil is very much clay, commonly referred to as “gumbo”. I have been spending time removing all the small roots from the cut material, and now need to backfill and stabilize the holes. I will be building a pad about 2’ high on top of this.

If I am not mistaken, the proper method for compaction of clay soils is a sheepsfoot roller, however if I use the cut material for fill, how will I beable to run a roller over it in lifts? (the holes are about 4-5’ deep, 10-12’ in diameter)

I was thinking about mixing sand with the clay, and even adding some lime. And compacting with something other than a roller??

Any thoughts here?...The geotech quote was a little out of the budget, but may have to resort to it.

Thanks in advance.

 

[kvom]

Good topic. My garage project sites the back of the slab at a point where there is currently a 30' maple tree with a 6-7" trunk. I'm going to make sure the stump and roots are pulled out. Good advice about leaving a few feet of trunk for the backhoe to work on.

 

[Deltarat]

Thanks for all the advise guys. Considering all of your comments, I have decided to move the shop to the other side of the yard. I only have one bradford pear tree about 6" in diameter to deal with.

 

[Bib Overalls]

The delta soil that I am familiar with is very sandy. It washes into voids and compacts hard. In your area back filling with tamped organic matter free soil may be a back fill option. Certainly worth investigating.

There is a lot of rock in the hills of Arkansas. We send train loads of it to Mississippi and elsewhere for construction purposes.

It all sounds like good advise, but I live in backwoods Ms.Delta. We are 50 miles from any rock and then all we can get is washed or clay gravel or slag- the grey rock that they put on the roads. I don't think you could find crushed stone or stone dust in the state of Ms. The gray rock lays pretty close so it may be my best bet.
After hearing your advise, I am going to make sure my shop is not over the stumps. If I have to tear up the concrete later, at least it will not be under my shop.
If anyone has any other comments, I am open to all suggestions.

 

[Torque1st]

How did you find a two year old post to reply to???

 

[James E]

My garage build starts tomorrow. Twelve or thirteen very tall and very mature trees have to come out. Mostly hardwoods but a couple of pines. The tree guy is going to limb them, then cut them about eight to ten feet high. Then use his front-end-loader with a claw blade to push them over and pull the stumps out. I'll have to pay for the stumps to be hauled away but you do NOT want rotten stumps under your garage or your driveway. You cannot grind them down enough. They will always rot and form a void under the slab. Bad news.

 

[trbomax]

ive knocked over trees 4ft arond or bigger with a backhoe.push as high on the tree as you can without breaking it. DO NOT break the tree when pushing over, it makes for a lot more work getting the stump out. if the tractor wont push it over, dig around the tree and push again, it will do it. the fastest way to clear is to push the whole tree over, stump and all, then do your cutting while its laying on the ground. whoever does the dirt work for your building pad will be able to knock them over no problem.


you can use dirt to backfill the hole, but if it was me, id scoop out all the disturbed soil and backfill with rock. if you use clean rock (more expensive) then theres no compaction needed. crushed stone is cheaper but youll have to compact

This is my preferred method.The wife and I had to take out about30 of them when we started on the new building.After she severed the stump in the hole,I would roll it a dozen times or so and shake the dirt out,pick it up and stack it off site. Its pretty amazing up here (we are all yellow sand) how little fill you need when you can shake em out.WE would run water in the holes untill they started to fill,then started dumping more dirt in from the site.In a day or two I could run the tracktor over it and compact it.They stayed spongy for a week or so,but once the water is gone there ok

 

[cowboy73]

After you dig the stumps out with a backhoe, consider running a dozer through the area. A dozer should be able to clean up the remaining roots. Then get some good backfill and rock and regrade the whole thing.

 

[GarageEnvy]

Presumably the OP has already taken care of this issue but since the topic is gaining traction I'll just add that compaction is important in my area. I had stumps and shrubs on the perimeter of the garage but not underneath it. The original plan was simply to grind them down and remove the roots as best as possible. Fortunately I had a very good excavator with years of experience. After a little digging he said it would be best to go 2' down and build back up, compacting after every 6" of fill. If in doubt, rip it out but at least in my area undisturbed native soil with no roots or trees is considered to be superior than fill and compaction in many cases.

 

[bgott]

What, nobody dynamites stumps anymore?

 

[Torque1st]

What, nobody dynamites stumps anymore?

That would draw a squadron of black helicopters from HS and a whole mess of SWAT teams. Plus the environmental impact statement would be 1000 pages long and require a year of study.

 

[hetkind]

When I built the shop last year, we had over 50 stumps removed. We burned for weeks, and the contractor wanted to bury the remaining stumps in a hole to the side...

I had the pushed out of the way, and burned them some more, this summer, when the crew was back finishing up some drainage, I had all the stumps restacked with a backhoe and finished the burning. Now the ash has been raked and compacted and set up for ricks of stove wood for drying and storage.

Burying stumps is a great short term fix...

Howard