[stoneridge]

A guy who I did a quote and plan, for a drainage system, (4" socked tile, 3/8" gravel,heavy clay, standing water.....).had a trenching company tell him to stay away from the socked tile because of the clay.

His theory was when the clay combines with the water it will clog the sock around the pipe, making it useless.

I explained the purpose of the gravel, the grade of the trench,etc, but I told him I would check into it..

I have never experienced this or ever heard of this.

Anyone have any insight or experience with this "theory"?

Thanks in advance.

[VoodooChile]

I'm no soil scientist, but I've buried some socked tile in my time and I don't buy it.

Once the socked tile is covered in coarse gravel, with 1 or 2 layers of finer gravel on top of that, I don't see how enough clay migrates down to clog the sock. Clay soils are very cohesive, if that's the right word, and once compacted, it's difficult to believe enough particles would seperate off to clog the sock.

Other particulates could prove a problem, if say lime-stone grit was washing into the trench, but not clay.

Maybe some wall guys-- Bill Schwab, bjr, pennscapes, Stonehenge-- could jump in here?

[AZTLANLC]

Actually I think is true.
I don't know about around the pipe but if its all around the clear gravel the silt will clog up the fabric eventually, this happened on one job we went to look at.
After 6 months of installation the water was running around the fabric.
Other thing tough is the type of geotextile you use.

[Stonehenge]

Several years ago the engineers at Versa-Lok flip-flopped on this issue - a derivative of what you're talking about here, they encouraged everyone to wrap the drain tile and stone in an envelope of fabric, the idea being to keep the clay out of the drain. One year they started telling folks to not wrap the stone in fabric as the fabric would clog and create a hydrostatic pressure issue at the fabric. Then a year or two later, they were back to recommending the fabric.

My take on it is that there must be something to the possible issue of clay clogging up fabric, whether it be around the clear stone or around the drain tile itself (the sock), but that there just isn't a perfect solution.

As far as what to take back to your client - tell him it's unlikely that any significant portions of the sock would clog, enough to prevent any drainage. However, without a sock, those same particles will get into the pipe and clog that instead. Let him pick his poison.

That clay silt won't disappear if the sock isn't there.

For your purposes, you might even consider doing the envelope of fabric around the drainage stone, to address this potential issue and your client's (and his advisor's) concerns.

[agla]

You could use pvc with the two rows of holes and then pitch the pipe fast enough so that the clay does not fall out of solution.

Speed is the mechanism that will hold the clay in the water. Once it slows down, it falls out. I saw some socks get clogged when I worked in Idaho. That is where I learned to hate flexible perforated pipe. There was a lot of clay and silt. One thing that we did was to use a stone with fines in it (5/8"-) rather than drain rock for back fill. That seemed to keep the drain pipes from clogging, and kept the face of the walls clean when they wept. The soil there was hard as a brick when it was dry and melted like ice cream when it got wet. A shovel full weighed a hell of a lot more than anything you can put in a shovel on the sand bar that I live on now.

I think some of the reason why the water ran clear through the 5/8- was that the particles were so close together that the water dispersed over the whole interface rather than following any one path of least resistance. That is what it seemed like, but it might not be the same situation where you are.

[cutntrim]

Last year we put 160' of low retaining wall along the perimeter of a suburban residential backyard. They'd had major drainage issues and when we dug up the existing weeping tile it was completely clogged with clay. We put in fabric, then drainage stone then sock-wrapped weeping tile and connected it into a dry well at the far corner of the backyard. Wasn't much else we could do, since the pipe heading into the next yard was clogged too so we couldn't connect to it.

[John LaPointe]

There are many different types of geo-textiles/filterfabrics. The soil needs to be tested so the correct fabric can be chosen to protect your pipe from sediments and to allow water to pass freely.

[Pelican]

Originally posted by agla
You could use pvc with the two rows of holes and then pitch the pipe fast enough so that the clay does not fall out of solution.

The theory of your statement is correct, but job conditions rarely permit the practical application of this. If you are installing drainage behind a wall, either one end of the pipe will be elevated above the footing, or the other end must be significantly lower than the footing, and an outlet must be acquired that is lower yet. On level areas this would be very difficult.

What I have been doing in this situation is lining the trench with filter fabric before the clear stone and pipe are installed. This prevents fines from contaminating both the perforated pipe and the clear stone at the same time. Also, there is a much greater surface area of filter fabric so that any clogging of it will take an extremely long time.

I've got curtain drains that were installed over 10 years ago that are working fine, and have yet to have a report of any failing. It costs a few dollars more to do it this way, but I think it is a more dependable solution.

[mark allen]

I took the NCMA testing a yyear or so ago, and they said not to put socked tile behind walls because of the limestone (typ) drain rock getting washed off and 'caking' up the sock.

Why can't you put in two, one with and one without and get back to us.......He could be our test site..... I can see it now....

[John LaPointe]

[quote]Originally posted by Pelican

What I have been doing in this situation is lining the trench with filter fabric before the clear stone and pipe are installed. This prevents fines from contaminating both the perforated pipe and the clear stone at the same time. Also, there is a much greater surface area of filter fabric so that any clogging of it will take an extremely long time.




This is my approach as well.

One other note is that PVC is a much more reliable drain pipe especially if you have the opportunity for flushing. Flexible, corrogated pipe encourages sediments to fall out of suspension, which is the opposite of what we would want. Also, corrogated pipe can not be flushed.

[Pelican]

Originally posted by John LaPointe
One other note is that PVC is a much more reliable drain pipe especially if you have the opportunity for flushing. Flexible, corrogated pipe encourages sediments to fall out of suspension, which is the opposite of what we would want. Also, corrogated pipe can not be flushed.

It sounds like your referring to what we call ADS, 4" black corrugated pipe available in coils. It is more economical than PVC and is easier to work with in some cases where the trench is not straight, but I agree that PVC will function better. Each of the ridges cast into the ADS serves as a point for debris and sediment to lodge. It also restricts water flow to an extent. If you aren't careful in laying it in the trench, you can end up with high spots along the length of the trench, also affecting performance.

ADS is more likely to collapse under the weight of the stone than PVC as well. I've seen it happen to my surprise.