Leveling a site for a pole barn that had trees

[LT1Pat]

I'm starting to level a site next to my house for a 40x80 pole barn that has some smaller trees and one large (~32" diameter elm tree). I plan to have a concrete slab poured that's 6" thick. I've excavated a circle around the smaller trees to the point where the tree falls over with the stump attached when I push it with the tractor. I plan on putting at least 12" of crushed concrete over the entire 40x80 area because it needs to be raised some.

Question 1: There is likely smaller roots that extend a decent distance from the tree. How critical is it to get these smaller roots that might exist that are 5 feet or more from the root ball?

Question 2: I have a rollover box blade that can dig in the ground and grab roots that might be 6" or so below the surface. Would it be better to leave the ground undisturbed or tear it up and attempt to get any tree roots that it catches?

 

[Stimw]

It would help if you posted your location, also what kind of trees?
I put up a 40' X 60' Red Iron Building a year ago on undisturbed ground.
The concrete guys spent about 4 hours with a Plate Compactor and wetting to keep the dust down.
Plans called for ground to be compacted.
The ground should be compacted then the fill should be compacted.
Roots? need to know what kind of trees.

 

[LT1Pat]

I'm in SE Michigan.

The site has 3 trees that are significant. The biggest being a 32" American Elm and then a 16" Willow tree and a 12" maple tree.

It would help if you posted your location, also what kind of trees?
I put up a 40' X 60' Red Iron Building a year ago on undisturbed ground.
The concrete guys spent about 4 hours with a Plate Compactor and wetting to keep the dust down.
Plans called for ground to be compacted.
The ground should be compacted then the fill should be compacted.
Roots? need to know what kind of trees.

 

[bigtiller]

When the pad for my 54x75 tin shed was made, 12" of top soil was removed and 3 trees and stumps about the same size as yours was pushed off to the side with a big bulldozer. That took care of all the roots that were big enough to worry about. Then the pad was built up in layers of clay and compacted with a vibrating sheepsfoot compactor with 5' tall wheels. A bit of 3/8 rock and 6" of concrete covered it all up. I don't think I need to worry about any settling.

 

[EddieWalker]

Don't worry about the roots. They will remain just like they are for decades. Without air and water, they will never rot.

Virgin soil will always have the highest level of compaction. When I worked construction in CA, we would have to get the soil back to 97 percent compaction. This was very hard to do, and we where using heavy equipment. The inspector would test it with a device that is kind of like radar by sending a signal into the ground and measuring it's echo. Most of the time we passed, but when we didn't, we would have to dig it all out, add a bunch of water to the pile, mix the pile over and over again with more and more water until the operator felt it was ready to try again.

You will never be able to get to 90 percent compaction without the proper tools, and even then, it's not easy. Do not dig up anything more then you have to, and be sure there is a enough moisture in your soil when you put it back in and compact it that it sticks together.

 

[RNeumann]

When the pad for my 54x75 tin shed was made, 12" of top soil was removed and 3 trees and stumps about the same size as yours was pushed off to the side with a big bulldozer. That took care of all the roots that were big enough to worry about. Then the pad was built up in layers of clay and compacted with a vibrating sheepsfoot compactor with 5' tall wheels. A bit of 3/8 rock and 6" of concrete covered it all up. I don't think I need to worry about any settling.

This is the standard construction practice. Organic material will settle or move differently than the native soil.

The pole barn shouldn't be affected as the design should have the poles set below the high organics soil. Your slab will be more prone to movement etc if you place your flatwork on top of high organic soil. I'd take the top soil off prior to placing imported material.

 

[LT1Pat]

Here's my plan:

1.) remove the top 6" of soil or until all organic matter near the surface is gone
2.) Build the barn
3.) Bring in 200 tons of crushed concrete to build/compact the gravel in 3" lifts
4.) Wait 3-4 months
5.) Fill with concrete

I'm hoping that winter and 3-4 months will bring that last bit of compaction.

Does this sound like a

 

[Firemanbuck82]

Spend less time worrying about the roots and more time filling the stump holes with structural fill and compacting to a "firm and unyielding condition". Poorly compacted fill will result in structural failure of the slab over time more than a few 2" diameter roots will. The slab and underlying gravel base will bridge over the occasional decaying root.

If you're worried about it, or if you have problem soils like swelling clays, get a qualified geotechnical engineer or engineering geologist out there to have a look and give you specifications on compaction criteria, sub-slab gravel layer, reinforcement within the slab, etc.

 

[EddieWalker]

Here's my plan:

1.) remove the top 6" of soil or until all organic matter near the surface is gone
2.) Build the barn
3.) Bring in 200 tons of crushed concrete to build/compact the gravel in 3" lifts
4.) Wait 3-4 months
5.) Fill with concrete

I'm hoping that winter and 3-4 months will bring that last bit of compaction.

Does this sound like a

Do you have topsoil? Did you post your location? Here in my world, we do not have top soil. It's red clay from top to bottom. I've seen posts from others on here who do not have top soil, but for some reason, they went to a lot of trouble and expense removing 4 to 6 inches of dirt for no apparent reason. I've been to places in the Pacific North West where the top soil is several feet deep. I lived in CA where we had several inches, but just a few miles away, there was none.

Why build the barn first? If you are bringing in crushed concrete and building it up, you will have a lot better results doing that without a building in your way. It is also a lot easier to build the building with a solid pad under you while working.

If you are going to pour concrete, why not do that first and then build your barn on top of the concrete slab?

 

[s219]

I asked around here for recommendations/experience when preparing my pole barn site and the consensus was to avoid making big holes when removing stumps and roots, because they are almost impossible to fill back up to a reliable level of compaction. People would rather grind stumps than dig them out. If you will be covering everything with compactable fill gravel for the base, it will help even out support for the slab regardless of what's underneath, but it can't make up for big soft pits left by stump holes.

So, I stripped all top soil down to clay (about 6"), flush cut and/or ground all stumps, then covered with compactable fill dirt (clay/sand mix) in 2" layers, followed by #78 gravel.