Proper Installation of Corrugated Pipe for Drainage Purposes

[DaileyJohn.20.decij]

I have had a leaky basement, and I had corrugated polyethylene pipe (about 4 inches in diameter) installed on two sides (South and North sides) of my house under about 8 inches of soil. There is generally a slight back to front slope on the house (with some depressions that would block water), and I was hoping that the pipe would take the water past the front of the house and ultimately to the street that is in the front of my house. On the South side of the house, there is about 25 feet of pipe from the first drain opening (located at the very back of the house) to the second drain opening, and there is generally a downward slope between the two drains on the surface. However, when I ran a hose full blast down the pipe for about

10 minutes no water reached the downstream second drain. The installers stated that since the pipe was permeable (and the ground is dry) that could explain the lack of water flow to the second drain. I understand that the pipe is permeable, but it seems to me if the pipe had an adequate consistent slope downward, some of the water would have reached the second drain. So, my question is, is pipe properly installed or have the installers failed to construct a proper downward slope when they installed the pipe? Or are other forces at work.

The parallel pipe installed on the North side of the house does drain some water, but the water flow is slow although my water hose test (hose going full blast for 15 minutes) only resulted in a slow flow of water to the corrugated pipe's endpoint, which was about 25 feet from the point at which I ran a hose into a drain to test the flow.

Any help with these issues would be appreciated.

Thanks,

JD

[hallerb]

these pipes under the basement floor?

if they were installed in a bed of gravel thats about what you should expect.

check outles at next rainey time.....

i did much the same checking a indoor perimeter drain system that drained to a sump pump, hose ran for a couple hours in a small home before I saw much activity. I watched the install carefully so I knew it was properly installed, the dry ground and gravel bed suck up the water

[m Ransley]

Hopefully they installed the pipe with drain holes on the top and sides, not bottom.

[DaileyJohn.20.decij]

The pipes are not under a basement floor, but they were > if they were installed in a bed of gravel thats about what you should > expect.

[Lawrence]

The point of the pipe is to increase the volume of the drainage field beyond what the gravel alone would handle. It is usually wrapped in landscape fabric and directs the flow of water in a specific direction. Flooding the field with a hose is not a good test compared to an actual rainstorm. A better test might be: Does the basement still flood in a storm??

It is entirely plausible that the drainage was indeed installed correctly and in fact was done so well that its' capacity greatly exceeds the volume of youy garden hose to the point that all the water is indeed sucked up by the gravel and surrounding soil long before it gets downstream. this is what you would hope for since a big enough rainfall could overwhelm any drainage field. I wouldn't worry until a big storm is forecast. then just make sure you check the basement for leaks and the downhill pipe for volume. then you will have a better ide of what's up with the install.

[DaileyJohn.20.decij]

[Michael Strickland]

The gravel bed does not "suck up" water, it increases the area which funnels the water to the pipe and facilitates the water getting to the pipe with the voids between the pieces of gravel. The surface area of the pipe is much smaller than the outer surface area of the gravel bed. When the soil becomes saturated, water fills the voids between the gravel from the surrounding soil, then is guided to an outlet point when it enters the pipe. This is just the opposite of a septic drainfield in which the pipe carries the water out to the gravel bed and the increased surface area around the gravel bed can absorb more water that what could be absorbed directly from the pipe.

If you put water into the pipe with a hose, that is not a real test of proper installation because you are essentially doing the septic system thing by putting water into the pipe. The gravel and increased soil surface area around the gravel bed can put a way a lot of water, particularly if it's put in at the upper end and you're looking at the lower end.

If you ran water onto the soil surface above the pipe, that is sure enough not a test as the water will disperse into the surrounding soil - most likely at a rate that would require several hours, minimum, of running the hose to get any result. You must keep in mind that the soil surrounding the gravel bed must be saturated before water can move to the pipe - that requires that it be saturated from the point that you're putting down water to the lower end of the gravel bed or the water will be moving into the soil instead of the pipe. That "test" is similar to opening the front door and waiting for the outdoor temperature to go down 10 feet from the doorway due to the AC running...

You really need to wait until you get a good rain - and I don't mean just a heavy shower lasting 15 minutes or so. A good all-day rain or several rainy days will be a much better indicator of whether or not the pipe is installed correctly. The soil must be saturated in order for the water to move into the gravel and then the pipe.

After a good rain, you should see that the water runs from the pipe for some time after the rain quits - a sign that the pipe is doing its job correctly, removing the water as it percolates through the soil. How long it runs afterward will depend on your soil (type and compaction) and how well it absorbs water.

HTH

Later, Mike (substitute strickland in the obvious location to reply directly)

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