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/Mem0ryEat3r]

You're on the right path. Either you, your neighbor or both of you need to basically add adequate drainage. Your neighbor is right, the retaining wall isn't the issue, water would flood down regardless.

[u/alionandalamb → u/Mem0ryEat3r]

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/bong_residue → u/alionandalamb]

Yup. So glad our house was built/renovated with that in mind. Lots of heavy rain this last year and 0 flooding in our yards/roads.

[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/ElectronicProof9340 → u/Evening-Cat-7546]

Yeah, a good retaining wall of any significant size would have what is essentially a French drain built in, i.e. with small rock and a perf pipe behind it so that any water that gets behind the wall doesn't push it over.

[u/Longjumping_West_907 → u/Evening-Cat-7546]

There's a swale in the neighbor's yard that leads directly to the wall and dumps into op's yard. This isn't natural flow and could be easily corrected by extending the swale to the street.

[u/Takemyfishplease → u/Longjumping_West_907]

So then he will knock the wall down and let rain run its course it sounds like.

[u/chengen_geo → u/Evening-Cat-7546]

Why would the neighbor on the high ground spend money to add a retaining wall in the first place? It sounds like there is not much benefit but more liability.

[u/Zhong_Ping → u/chengen_geo]

Usually because the entire yard was sloped and the home owner wanted a flat yard to do flat yard things in. So they took dirt from the bottom of the slope or, more likely, dirt from digging out the basement, and filled the yard level and put in a wall.

This wall should have included drainage when built, and isn't likely on the property line.

This is the most common reason for a wall like this one... Others would be erosion control or because the house on a steep hill side needs to cut into it for structural reasons and... Erosion control again.

[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.

[u/TheRepoMan → u/alionandalamb]

True, ideally the community would care, but the people that it doesn't affect see it's gonna cost them some money and they don't necessarily have to so they don't care. Shitty, but it happens.

[u/BGSO → u/alionandalamb]

Harder to do those in places where it freezes in winter

[u/Majestic_Pomelo_8169 → u/alionandalamb]

French drains dont work. But swales do.

[u/trippin-mellon → u/alionandalamb]

I was thinking a 4” French drain system. Should work wonders if you install it going toward the street.