drain tile

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  #1  
Old 04-19-03, 10:49 AM
dirkwright
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drain tile

Hello, I have a drain tile question. My house is about 35 years old and it has a full basement. I bought the house a couple of years ago, so I don't know how the drain tile is arranged.

I have a basement door that is half below grade. There's a sloping sidewalk up to grade, and at the bottom of the sidewalk at bottom of the door is a 2" floor drain. The drain was made by busting the clay drain tile and re-mortaring it back together with the drain hardware installed. There's no protection for this area, so plenty dirt and leaves collects in and around the drain. When I bought the house, the drain was completely plugged. I used a shop vac to clean it out, then snaked it about 12 feet. It works, but slowly, and I know I will have to repeat the cleaning. The original door was rotted from water damage, and heavy rain would back up into a small room there. Fortunately, the drain in the floor of that room works good.

Recently I decided to determine if in fact the drain tile went anywhere, and if so, where it went. The drain in question is about 4 feet from a corner of the house, and I had noticed that the water in the drain flowed towards this corner. This corner is also the shallowist of the house, with the footer about 4 feet below grade. So, I dug a hole at the corner down to the drain tile to see what I could see. Well, it doesn't drain anywhere! At the corner are just the two clay drain tiles, one heading towards the door, the other heading along the back of the house. The one along the back of the house is clogged with dirt. So I have no idea where the water goes, and there is a further complication.

The part of the basement behind this door is a small room. The floor of the room is two cinder blocks above the rest of the basement. This little room was a retrofit, since it used to be a cawlspace under a small sunroom. This floor is at the depth of the footer, which is 4 feet down. The rest of the basement is deeper, so can I assume that the drain tile for the rest of the basement is also deeper? I don't know yet if the drain tile that heads from the corner of the house where I dug continues on to the rest of the basement, or if it ends at the step in the footer. I'll find that out when I snake it soon. So, does anyone have any ideas what happens to the drain tile at the step in the footer?

To add to this difficulty, I need to make a place for the water to go from that sidewalk drain, and also make it so that I can clean it out once in a while. Before I realized that this drain tile is probably not connected to the rest of the basement drain tile, I was going to install an outside cistern and sump pump to bring the water back up to the surface and dispose of it that way. But if this drain tile is only for a small area and not the whole house, then I'm not going to bother. I am currently considering just building a cinder block cavity at the corner and just burying it. I won't be able to clean it out from that end, but I suppose it would be better than what I have now.

I would also like to appeal to any wisdom on this forum about drain tiles in general. I thought that normally, the drain tile either extends away from the house until the ground slopes down far enough for the tile to exit at the surface, or the tile empties into a pit of some kind, either with or without a pump. My lot does not slope fast enough to allow the first alternative, there is no pump, and have doubts that there's a pit either. We are on well and septic, so there is no storm drain for this purpose. The reason I doubt that there's a pit is because most of the basement is about 6 feet below grade, and any pit would have entailed a huge amount of digging. The basement has a history of water problems, none severe. There are also a couple of floor drains that don't drain. I've snaked one of them and it just went to gravel.

So, anyone have some spare time to waste on answering my questions? Any help is appreciated.
 
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  #2  
Old 04-19-03, 08:53 PM
Doug Aleshire's Avatar
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dirkwright,

This is a general overview of drain tile installations...

The best way of keeping liquid water away from a foundation is to divert downspouts away from the house, and slope the ground away from the house. In that way any rain, snow melt, etc. will not drain down into the soil near the foundation. For any water that does drain down into the soil near the foundation, and also for any excessive ground water already in the soil from a high water table, a perimeter drain tile and stone or gravel backfill has been the standard approach. This is a waterproofing system. The same application is done to the "interior" of the lower level and this works extremely well especially in older homers when exterior applications cannot be done.
When liquid water gets into such a gravel backfill, it quickly runs down into the drain tile and is diverted away through a pipe either by gravity or a sump pump. When a drain tile is used, but soil is used for backfill, the water can't drain away as quickly, so it tries to drain through the foundation wall. If enough liquid water is present, hydrostatic pressure will force it through any opening it can find in the foundation wall, no matter how small.
The purpose of the stone or gravel backfill is to relieve the hydrostatic pressure. With the correct backfill material, the liquid water will travel the path of least resistance: through the backfill into the drain tile, rather than through the foundation wall. I will point out that drain tile comes in two styles - rigid and flexible. The rigid has a slot on one side and this is installed with slot down. The flexible has slots on 4 or 6 sides, if you will but this should be installed with a silt sock over it. Costs more but prevents silt from getting into the pipe. Most homes, for interior applications use the flexible but either is acceptable.
When the soil is merely damp, as it often is, liquid water isn't the problem. When damp soil is next to a foundation, it will cause the foundation to get damp. The dampness will work its way through the foundation wall and eventually enter the basement or crawl space. Concrete and masonry are actually very porous, so dampness can move through such materials fairly easily. (This is done through a process called capillary action.) Once the dampness reaches the interior surface, it can evaporate into the basement or crawl space, increasing the moisture in the air.
To stop the dampness is relatively easy because, by not being in liquid form, there is no hydrostatic pressure. A simple foundation coating will do the job. This coating is called dampproofing. It isn't a substitute for waterproofing.

PROCESS: Remove about 16" space out from wall. Ensure that you are about 8 inches out from footing. Dig a trench along the footing that slopes gradually towards a sump basin. Trench approaches the sump basin from two sides. Drill " holes into each of the block cavities (2 per block) in the course of blocks that sits directly on top of the footing. Water now comes out of these holes when it rains. Place 4" corrugated drain pipe in the trench and run this all along the trench to the sump basket. You may use a silt cover or a silt sock which covers this pipe of which then you would place 3/4" pea gravel over this to a level that leaves about 4" of space for your new concrete. Place the concrete all the way to wall - NO SPACE IS REQUIRED. Install a good sump pump and PVC piping - 1 1/2" out to the exterior and away from the homw for proper drainage. This could be buried and run into a drywell at least 20 plus feet away from the home on down grade.

Take a look at these...

http://www.dspinspections.com/basementwater.htm

http://www.binkleyandober.com/residential.php3

http://www.usinspect.com/Crawlspace/PerforatedPipe.asp

Hope this helps!
 
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Old 04-21-03, 06:27 AM
dirkwright
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Thanks for the overveiw of basement drainage systems Doug. I was already aware of almost all that you said. I'd still like answers to these questions:

What is the typical solution to installing exterior drain tile when the foundation is stepped? Do they have separate water disposal systems? If I don't have a disposal system for my basement drain tile, how and where should I construct one?

Is it strange or unusual for exteroir drain tile to not have a sump or pit? How would you decide how big and deep to make such an exterior pit?

As I tried to explain, my house does not appear to have any place for water collected by the drain tile system to be disposed. I do not have an interior sump or even interior drain tile. There are a couple of floor drains that don't work, yet appear to drain towards the footer, so I assume they are intended to drain into the tile system. Obviously, I'm puzzled by what I have, or apparently lack. I don't want to install a sump basket because they are primary sources of radon according to the EPA. I'd have to install a radon abatement system in addition to the sump system. That would be far to complicated of a solution for me. I prefer simple solutions.

I'm planning on simply making a pit for the drain tile that runs from the sidwalk drain and running some pipe to it. I'll make a cover for the pit and bury it. Hopefully, if the pit is big and deep enough I won't have to worry about it again.

Thanks again.
 
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Old 04-21-03, 07:34 AM
Doug Aleshire's Avatar
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dirkwright,

What is the typical solution to installing exterior drain tile when the foundation is stepped? In stepped situations, the drain tile still follows the footing. In some cases only the lowest footing will have tile installed...not the best idea if we have bad soil conditions as this could allow water infiltration at the higher level.

Do they have separate water disposal systems? Some applications for exterior run a buried line away from the home to a drywell but in many cases this is directed to a sump basket within the home and this is pumped out to a drywell or away from the home below grade to an area that has gravel covered with silt cloth and soil/grass over it.

If I don't have a disposal system for my basement drain tile, how and where should I construct one? You have options but your concerns on radon is limiting your options. Bear in mind that radon can leak in through concrete block - POROUS, cracks between walls/slab. A basket with cover will not hurt anything but if you are not providing proper ventilation, radon can be an issue. I have attached a link for more info.

Is it strange or unusual for exteroir drain tile to not have a sump or pit? Yes, you need to get the water to an area to relieve the water and not have it go through a "recycle" phase.

How would you decide how big and deep to make such an exterior pit? I have used 30 and 55 gallon drums - half filled with gravel, buried in the ground. The method varies based upon who is doing it.

http://www.radonseal.com/radon-instructions.htm

You may want to consult a professional in your area on the drain tile, basket and radon for what is appropriate for your home.

Hope all this helps!
 
  #5  
Old 04-22-03, 05:57 AM
dirkwright
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Thanks Doug!

About radon: when I bought the house, I measured high levels of radon in the basement. I plastered the concrete block walls with Thoroseal, and the radon level went way down. I also sealed up the crack between the floor and the walls to further reduce radon infiltration.

I wonder if there is a 55 gallon drum buried in the yard and maybe it collapsed after 35 years?

I'm planning on making a drywell for the sidewalk drain, and also include a cleanout at the surface. I need to find an auger type post hole digger that can be extended. I can't find one for sale.

Anyway, thanks again!
 
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