French drainage system between two houses

Old 10-16-16, 08:43 PM
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French drainage system between two houses

Hello and thanks for your time,

I already built this but I'm having second thoughts and I just wanted to get some experience opinions.

Between my house and my neighbors house is an 11 foot wide space where grass hardly ever grows. It run 55 feet long from back to front of houses.

We removed the grass and dug out a 3.5 foot wide trench on the property line that was 1 foot deep and that runs 55 feet from back to front of house. We placed a black liner material from house to house and into the trench.
My side slopes down about 4 feet into the trench and the same thing for my neighbor. We filled the trench up with clear gravel and placed a perforated black plastic pipe from back to front of house and in the middle of the trench. We then covered the pipe with 2-3 in of crushed stone and placed slabs on it to make the walkway. On to the left and right of the walkway we placed some river rock for aesthetics and to keep the slopes running into the walkway.

So there is probably a good 4 in of gravel underneath the pipe, then 4 in of pipe then 2-3 in of gravel to bring it up to grade. Also there is a soft, gradual
1 degree slope from back of house to the front of house, so water should move towards the front of house, which is where I want it to go.

Just to make things more complicated, I have a downspout in the middle of the house that dumps water out by 3 feet away from foundation and towards the walkway.

My question is, will this system work? My goal is to keep water away from foundation walls and root it out to the front. Will the walkway interfere with anything? Is the gravel trench too wide?

Looking for thoughts. Thanks,
Old 10-17-16, 04:51 AM
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You said you want the water to move to the front but never said if it had anywhere to go. If it slopes downhill enough for the water to drain out of the trench then it should work fine.

If the trench you dug has nowhere for water to exit you have to consider that rock does not make water magically disappear. If water would not soak into the ground before then digging a shallow hole and filling it with rock will not make it soak in either. What it gives you is some accumulation like a storage pond to allow more time for evaporation or for it to soak into the ground.
Old 10-27-16, 07:50 PM
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Where does the trench go once it reaches the front of the house? Is the front yard noticeably lower in elevation whereby the trench, if continued all the way to the property line, would let excess water out there? The main purpose of the gravel surface is to keep people from falling in. The gravel surface can be made reasonably good looking.

A "French drain" with no exit is more properly called a leach field or a detention pond even though it might be constructed in the same manner as a French drain. Gravel has a tendency to harbor water compared with clay with a suitable slope that water would run down and onward.

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