Initial excavation for gravel road build... how deep?

[4570Man]

Three foot of soil? You won the dirt lottery!

My place is rocky enough for a passable road in some places without any additions. I have never used the geotextile. I use a 3/4" and under crushed rock with lots of stone dust. I wish I needed all the prep you are considering.

Same here. A few load of rock is really cheap compared to having nothing but rocks.

 

[EddieWalker]

Clay is not top soil. Top soil is the organic material that falls from trees and has been decomposing for thousands of years. Here in East Texas, we do not have top soil. We do not remove good solid clay base. Scrape off the grass if you want, but cutting it short is all you really need to do. Drainage ditches are what's really important, not digging a trench to put the gravel in. Fabric doesn't hurt anything, but it's rarely needed. For most, it just makes them feel better about their road. Then put 4 to 6 inches of road base gravel down. Your County will have the best specs on what works there, so just get the same road base that they use.

 

[stuckmotor]

Eddie,
Why don't you have top soil? I've heard that about part of Texas before.
Stuck

 

[ruffdog]

You don't build a road or drive for the best conditions, you build them for the worst conditions (heavy rains, frost coming out, heaviest weight). I had a good 18" of topsoil taken out and had 18" of 4" limestone put in. Then the guy used his vib roller on it. That shoved the rock down into the subsoil some. He followed up with 3/4" stone to 4" above grade. Over time, it settled down some so I topped it with a load of gravel. When the ground is gooey because the frost is coming out, I can still have the propane truck back down the drive without it sinking.

 

[rustyshakelford]

You don't build a road or drive for the best conditions, you build them for the worst conditions (heavy rains, frost coming out, heaviest weight). I had a good 18" of topsoil taken out and had 18" of 4" limestone put in. Then the guy used his vib roller on it. That shoved the rock down into the subsoil some. He followed up with 3/4" stone to 4" above grade. Over time, it settled down some so I topped it with a load of gravel. When the ground is gooey because the frost is coming out, I can still have the propane truck back down the drive without it sinking.

Unless you get rock for free that is unimaginable here. Putting down almost 2’ of rock blows my mind. We have 4” and that’s plenty. Maybe add a little every couple of years to build up what’s sunk down

Brett

 

[swnoel]

If you have 3' of top soil (loam) congratulations! Dig it out and replace it with back run then top with 4" of 1 1/2". Sell the top soil to help offset your cost!

 

[EddieWalker]

Eddie,
Why don't you have top soil? I've heard that about part of Texas before.
Stuck

A long time ago I thought everyone had top soil too, and that you had to remove it before building. But then I saw buildings, parking lots and roads being built on the existing soil and started to wonder about that. Eventually I learned that there was no top soil there, and that it's actually rare to have top soil in a lot of places. Where I'm from in CA, we have very rich, loamy soil that never stops decomposing, but if you go into the Hills, or to the other side of the Hills, into the Valley, it's all clay and hard pan until you get to the Delta regions, where all the crops are.

Here in my part of Texas, we have red clay. There are dozens and dozens of types of clay, and each has a load rating, along with a movement rating. Red clay is the best. It holds weight, compacts easily and barely moves. Plants love it because it forms a crust at the surface that is super hard, but just a few inches down, retains moisture all summer long. There is no loam, or anything that will decompose over the years. It just doesn't happen here. In my travels, I've found this to be true almost everywhere except the places where it's obvious just by walking and feeling the soil move under your feet.

Removing the dirt to create a trench just provides a place for water to go to and not leave. Basically you are building a shallow pond. Add rock to the pond and you will have less area for water, but water will still find a way into there. It is much better to build up the road base so the water goes "away" from the road. Dirt, or red clay, is the cheapest, most available materiel to do this, so that's what we use. Either haul it in, or use what is dug from the ditches along the side of the road to build up the road bed. Then compact it and spread your road base rock over it.

Part of my land was a World War Army Base called Camp Fanin. The dirt roads are still in good shape where the jungle has not taken them over. Ditches and crowned red clay is still there 70 years later and I drive on them all the time.

 

[Dadnatron]

This is topsoil. Black and grows anything. If I dig deep enough, I get into red clay.

I have a 'borrow pit' of sorts... basically at the back of the farm, where I want to eventually put an equipment shed, I have a small hillside. I pushed off the topsoil which, since it was at the top, only had about 14-18". I have been pulling red clay off the hill in a dual effort to flatten the hill for use and use the clay for my roads.

The issue I have is how much of the 'black topsoil' must I remove and fill back with the red clay? At the bottom of the hill is the deepest topsoil and it would require a LOT of dirt moving to remove it completely. And given I have simple 'farm use' of the road, I don't know that removing it all is necessary. I can pull the true organic material ie major portion of the subsoil roots, but I really don't want to pull everything. I have no real need for it elsewhere, as my property is 95% topsoil to at least 12" before the clay appears. I just don't think the 'bang for the buck' is there. But I don't want to have a crappy, problematic road which causes me nothing but frustration for the rest of my life.

I can cut out X" of topsoil, and build it back with clay to whatever level is best. I don't know whether that is like painting over rust though.

 

[ovrszd]

You only need to excavate deep enough to remove the organic matter (roots, grass etc.) then put down your geotextile and build up from there.

Yep, what he said.

 

[crashz]

It might be considered overbuilt by some folks, but your original road was built right. You want all of the organic soils out.

The topsoil will act as a sponge and in wet weather will be very unstable. If you wanted to build on it, I would replace about a 10" of the soil, place filter fabric at the interface, place 3" of stone, a layer of geo-grid and then 9" of dense graded aggregate. Compact in lifts. You would be constructing a mattress that will "float" on top of the remaining topsoil.