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LShaver
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Downspout overwhelms French drain and water enters basement-- how to fix?

There is a space of about 12" between my concrete drive and the house. 4" perforated PVC pipe is run the length of the house in this space and drains into the yard out back. The pipe is covered over with about 6" of clear stone. This French drain is under the eave of the house with a gutter, so very little rain water enters -- the drain is really there to deal with snow melt in the spring (I'm in Wisconsin).

At the back corner of the house I have a gutter downspout (3" by 4") that drains half the roof, about 400 sq ft. This used to dump onto a brick patio but this caused water to enter the basement and was damaging the patio. Then I diverted it onto the driveway, but this creates a sheet of ice in the winter.

Now I have connected it into the French drain. With a light rain, everything works fine. But when there's a heavy rain, the system is overwhelmed and I get water seeping through the foundation into the basement.

What options do I have to solve this problem?

Note that I am literally between a rock and a hard place here -- a 12" space between a concrete drive on one side, and the house (and then patio) on the other side. Three options I've thought of:

  1. Replace a portion of the drain where the downspout connects with solid PVC. Would this cause new problems? How far should I go in each direction?
  2. Rotate a portion of the drain where the downspout connects so that the perforations are on the top. In theory this would keep the high pressure water from the downspout from pushing out the holes in the bottom, while still allowing the French drain to collect water along it's length (though not as effectively in that section).
  3. Run two systems by digging up the 50' of French drain and running it deeper, then run the gutter drain over top of that. Obviously this would be a lot of work which I would like to avoid.

Here's an attempt to represent the situation -- red is the section I propose to replace with solid PVC (or perforated PVC with the holes facing upward).

House drainage schematic

LShaver
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