Base condition prior to installing road fabric

[JimMorrissey]

I started building the road to our new home site in the back part of our property.

First question: There are lots of small to medium sized rocks left after about 10" of excavation. The larger ones are about the size of hubcap and fairly hard to lift. Can I just try to level the base the best I can and put down the fabric, or should I get some material delivered to cover the raw base prior to fabric? --I'm wondering if I need to roll the base with a large wheeled vibrating roller to level it and force down the rocks......Obviously, I'd like to just lay down the fabric and cover it with crushed gravel, but I don't want to compromise the integrity of the fabric long term. The base is on the damp side with some parts of it soft and others firm. I really don't want to spend the money on sand or some other material before fabric, but I will if I need to.

Second question: What do I do about the really soft areas, places where I can get the tractor stuck? It's black and soft, swamp-like earth....I'm thinking that I'll have to dig away from the dry end, excavate and place the muck on the high side and fill after each 10' section is cleared; back up over the new fill and dig another 10" section until I'm done with the wet area......That freshly cleared section would get a layer of fabric and 6" of crushed gravel (3"). Then, on top of that would go another layer of fabric and about 8" more crushed gravel (1 1/2") --I'm talking about a section of road that is about 100' in length, so it's not too bad.

/forums/images/graemlins/confused.gif OR....do I just go down about 24" and fill the road section with the big 3" material a foot deep, lay down one layer of fabric and cover with another foot of 1 1/2 crushed gravel?

 

[steveinmo]

Jim,

I don't think you'd have a problem just putting the fabric down and then the base material over it. It would probably be best to level it as best you can, but I wouldn't go to a lot of trouble. The fabric will keep the base from disappeariing.

I just did this early spring at my new place. I didn't have the rock to contend with, just clay. But......I doubt that the fabric knows whether you have rock under it or not! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[DocHeb]

Isn't there a lot of problems with frost heaving of rocks in your neck of the woods? I would ask your question to the people that sold you the textile fabric.

 

[JimMorrissey]

Doc,

Frost heaving is definitely a problem in Vermont, but what to do....I can't clear all the rocks, it would be an ENDLESS project. I'm going to pick the big one on the surface and just lay it down in two 12' swaths. Most of the rocks are smooth from ancient glacial action which should help the fabric from getting easily punctured.

 

[JimMorrissey]

Here's a big rock that I had to pull. Most of the problem rocks are much smaller than this one. The L39 can actually lift that thing....pretty amazing loader.

 

[jim_wilson]

This is something you probably don't want to hear but - everything I ever read about road construction mentioned getting rid of any "organic" type soil before laying the roadbed. Last summer I excavated about 120ft to extend my driveway into my backyard where I plan to put a garage. To do this entailed taking anywhere from 18" to over 2ft of soil out before I got down to 'non-organic' sandly claylike soil (see attached pic). The problem with organic soils is that they retain water and do not drain well. I know the frost line around here (Northeast MA) is around 42" below grade. Up in VT it is probably deeper. From the pictures you posted it looks like you are still dealing with 'organic' type soil there. The picture of the rock shows some darker soil on top and then some medium brown type soil under that. It is my understanding of the fabrics that their job is to prevent the base from sinking into the ground - not prevent big rocks such as the ones you have from coming up thru them. What I found when doing my excavating was there was a pretty good amount of rocks in that 2ft of soil that I took out - but once I got under that the amount seemed to drop off. I guess the question you need to ask yourself is how nice of a road do you want this to be and how much work do you want to put into it? Leaving those big rocks you may find them poking up thru the road surface sometime down the road - pun not intended.

 

[jim_wilson]

forgot to attach the pic

 

[jim_wilson]

New England does have rocks......

 

[jim_wilson]

One thing to look at with these bigger rocks is if the bottom of them is below where the potential frostline is then you probably don't have to worry about them heaving too much. I did run into a couple of rocks when doing my excavating that that would have taken a backhoe many times larger than the BX to take out - I just left them because it was pretty clear that the bottoms of them at least were well below frost line - which I figured means they should not heave.

 

[JimMorrissey]

Jim,

Yes, that's why I'll just take the top off the huge one and leave the base. See my earlier "splitting rocks" post.

This section of road is about 100 feet or so, but the whole project is over 1000'. I'll just get the biggest rocks I can. There is just no way for me to get all the rocks and yes there is some "organic" material left, but that's OK. It's mixed with solid base and does not move when a fully loaded tractor rolls over it. I will excavate the softer material though.

As far as fabric goes, I had no illusions it would prevent rocks from coming up through. It acts as a tight drum to keep pressures from crushing your base and destroying the surface as well as preventing the mixing of materials. I'm certain it will work very well. If I need to grade the road now and again....then that's what my box scraper is for. I just don't want to have to be a slave to the road due to poor base preparation. I appreciate you posting your pictures....they make for more incentive to keep picking rocks!

Your drive looks like you could take a full cement truck over it without the slightest depression.....looks like three feet of excavation. /forums/images/graemlins/smile.gif