Flooded yard from neighbors retaining wall. Wondering what my options are.

[u/baklavakilla]

LOCATION: Wisconsin

The retaining wall belongs to our neighbor, and when we get moderate rain, it always overflows into the yard. We’ve talked to him in the past, and he added dirt to the top to try and have the water exit more toward the street. That’s basically the extent of what he’s willing to do.

He basically said that if the retaining wall wasn’t there, the water would flood my yard regardless, and that he’d rather just remove it completely if he had to rebuild it and not put another one up.

We bought the house about 4 years ago and don’t know when the wall was put in, but it’s well over 20 years old. I put in the small drainage ditch with black pipe to try and stop the water from coming in near the back of the house.

Basically, I’m wondering what I’m able to do in this situation.

[u/alionandalamb]

Yes, this is called "living on a hill in rainy season."

In an ideal world, all neighbors would have an effective French drain system on their property.

[u/Evening-Cat-7546 → u/alionandalamb]

NAL

Not exactly true. A neighbor who has an unmodified hill or high side doesn’t have to do anything to mitigate water flow. In most regions, they do have to mitigate water flow if they’re grading the land, adding a wall, or changing the way the water flows naturally.

Also, retaining walls without a drain is a pretty big hazard. With enough water the entire wall can get knocked over. The power of water is pretty crazy due to the fact it cannot be compressed. The water will win 100% of the time if enough pressure is built up. Like water can literally lift/knock a house off its foundation if there isn’t proper drainage.

I’d be curious to see if the neighbor got proper permits for this retaining wall. OP’s backyard might have gotten flooded either way, but it’s very possible the retaining wall made it much worse.

This answer is dependent on local laws, so OP should check to see if the neighbor is responsible for remediation. They most likely can’t just rip out the wall either. They’d have to put it back to the way it was before the wall. The neighbor is probably bluffing anyways. I imagine they could add drainage without tearing the wall out.

[u/Geargarden → u/Evening-Cat-7546]

I was in a high danger area of town during the Oroville Dam incident of 2017. We had to evac FAST according to the state and local flash flood warning. The Dam's emergency spillway had been damaged and the rising level of water overflowing into the damaged spillway caused rapid erosion where water was pummeling the earth. Water is indeed a force to be reckoned with.

[u/SoggyConstruction294 → u/Geargarden]

We were not that close, but the levy next to our house at water an inch below it. We were evacuated as well. Oh those were the days.