Soft Roadbed Issue

woodlandfarms · Feb 5, 2008

We have lived on this property for two years and are just figuring out its idiosyncrasies. Our driveway is around 800 feet or so, and at an 18 to 20% grade (according to a recent survey). There are a couple of spots that I am now realizing get soft once we get enough rain (same thing happened last year, by February, the spots get saturated and wheels sink in). The rest of the roadbed is solid, so I am not sure as to what to do.

I could dig it out, put in larger, then smaller rock, but I am not sure what is going to prevent it from sinking again.

Maybe I let it go until spring?

Looking for any advice on this one.

grnspot110 · Feb 5, 2008

I'm sure I will be "against the grain" on this one, I never use bigger than 3/4" gravel! It will take more to start with, but no more in the long run. 1 1/2" & larger will just make it spongy. Also bigger gravel has a tendency to work its way to the top. Good compaction is the best, & keep some crown to it so the water can run off. A flat road or drive will stay soft longer & pothole worse because the moisture soaks in instead of running off. Once my drive was 'settled in' I have only used 3/8" gravel. ~~ grnspot110

jeffinsgf · Feb 5, 2008

Greenspot is right -- I think he is against the grain on this one.

Larger rocks at the base of your roadbed, and bring the grade up in lifts with successively smaller sizes. I have 4x6 as the foundation, 1 inch with fines spread thin over that, then 1x2 with 1 inch with fines over that. I've thought about topdressing it with 1/2" or 3/8" clean (no fines) to cut down on the dust, but haven't done it yet. The 1" with fines packs into the larger rocks and locks it all together. Most of my road is as hard as concrete.

cjcocn · Feb 5, 2008

You could also try putting down some geotech after you dig down and before you start building your roadbed back up. That will prevent the soft stuff from working back up.

That is what is used around here by the Dept of Highways and it seems to work quite well. It is used both when building paved roads and on gravel roads as well, and was actually used just down the road from where we are. Used to be that when it rained too much, about 300 yards of our road (past our house, tho) would just turn to mud and after a while even 4x4s would get stuck.

They dug up the roadbed, laid down some geotech, and then built the roadbed back up. Has been solid and stayed dry since.

HTH

dirtworksequip · Feb 5, 2008

Woodland, to make any road hold up you need to get rid of the water. Find the source of the water and take whatever steps are needed to get the water out of the road bed,whether it is using a french drain, ditch or other means. I would say if you dig out the wet spot and fill it back in with anything it will eventually give you problems again. Any amount of water no how small will cause problems in a road. Keep it dry and your problem will disappear.

Sincerely, Dirt

2manyrocks · Feb 5, 2008

Post some pictures of the site conditions where you're having the trouble. That would help in offering suggestions. My blind reaction is it's drainage related, but the fix depends on what you've got on your site.

cjcocn · Feb 5, 2008

dirtworksequip said:
Woodland, to make any road hold up you need to get rid of the water. Find the source of the water and take whatever steps are needed to get the water out of the road bed,whether it is using a french drain, ditch or other means. I would say if you dig out the wet spot and fill it back in with anything it will eventually give you problems again. Any amount of water no how small will cause problems in a road. Keep it dry and your problem will disappear.

Sincerely, Dirt

Good point!

With an 18 - 20% grade I thought that the materials used to rebuild the roadbed would naturally promote the required drainage. BUT, in so doing I assumed (yes, I know how that word breaks down

) that the problem was in the roadbed and ignored what should have been a natural thing to consider.

My bad, thanks for the reminder to use my head for something more than keeping my ears apart!

john_bud · Feb 5, 2008

I'd vote on the drainage improvements, geotextile and the rocks outlined by Jeffinsgf.

jb

woodlandfarms · Feb 6, 2008

Lots happened to the road after I wrote this. First, due to some work by the county, they laid down a bunch of gravel and cut a number of "water channels" that had been washing out their construction site (and pouring onto my road).

I do see what you mean in regards to drainage. I sat in a downpour and watched the water coming down the road. The trouble spot does have water running over it, but not collecting on it. Maybe it slows enough..

So, now I need to figure a better drainage plan. I will post some pix tomorrow, but what I have is a downhill slop with a slight bend, putting the apex of the road on one side (not down the middle).

So, in the spring, after resolving this drainage issue... Should I dig the road up in this soft spot or just see what happens with reduced water on the surface?

sandman2234 · Feb 6, 2008

I am a wait and see kind of guy, as long as there is a chance that I won't have to spend the money to do something, I wait till I know for sure.
Worse case, you have to work on it during the heat, instead of in the cold.
David from jax