I need some help with stormwater management 2

[andyl9063]

I'm on an 1/2 acre lot, the house with all the red arrows. My neighbor is above me with raised elevation of about 10 ft high being where their house is and sloping towards the back of their yard.
This gradually slopes down to where my house is. All of their gutters drain to the back of the yard and of course it all slopes into my yard. Neighbor house is 4800 sq ft so big roof.

It is coming through my yard where the circle and down red is marked. Then it pools where the square is. I have attached a video where it drains into my yard on one of the biggest rainfall we had this year so far.
We are in Georgia so red clay and the yard soaks up the water pretty fast. Normally gone with 1 day or 2 days.
I don't want to resort to last option where I grade it where it drains to the neighbor besides me or the neighbor behind me. That's another issue.

What solutions are there? I'm thinking rain garden or a catch all pond. French drain wouldn't work because there's no where to daylight it and drain it properly. The left side of the back yard is uphill, about 15 ft high towards the road.
Retaining wall, but it would eventually fail due to pressure and the water got to go somewhere.

Video link:

https://imgur.com/JGmLGxM

 

[GeoEnvGuy]

Confirm with the municipality on the lot drainage plan before you make changes. From the aerial I can only make assumptions.

Looks like a front to back drainage pattern with the arrows provided.
Easement for rear lot swale may be in the trees or designed to drain towards the road ditch.
Elevated neighbour or lower side should have side swale directing water to back of lot as well.

 

[andyl9063]

I just found my land survey and it seems there's a drainage easement. I actually haven't gone behind my fence to take a look. It's covered with trees, bushes and thorns.
The arrows represent my yard slope.
I have attached a bigger picture from county gis.

 

[HTURKAK]

The arrows implies your backyard is local low . I will suggest you to construct an infiltration basin . Excavate a pit and fill with gravel surrounded with geotextile. Pls look to the links to see the concept

https://www.greening-solution.com/underground-water-tank/

https://www.gstanks.com/stormwater-infiltration-tank-m2016s/

 

[andyl9063]

what does local low mean?
I assume it's not possible to have sod on top of that pit? How do you determine how big the pit is?

 

[r13]

I guess "local low" means even grade with spot hi-lows.

You need regrade your yard towards a low collecting point. Then, build a collection pond, either pump the water out periodically, or divert to the nearby storm drain.

 

[cvg]

grade the lot to drain to the low outfall / towards the drainage easement. if you dont have an outfall, then to a retention basin. if your neighbor is directing water onto your lot (in a location that is not in the easement), maybe discuss with him that his negligence is causing drainage problems and could be liable for your damages

 

[andyl9063]

got it, thanks guys.

 

[Ron]

cvg...yep...exactly
Tried to give you a little purple star but not sure it's working right. Anyway, right on target with post, particularly neighbor contribution. Usually illegal.

 

[msquared48]

Cutoff trench at your fence line to catch the water and drain it to the ditch in the road.

Mike McCann, PE, SE (WA, HI)

 

[r13]

Good one, squared. Didn't think about it, which could be the cheapest/trouble free solution.

 

[andyl9063]

1. I don't think the neighbors did anything wrong. Their gutters is like 200 ft away from the fence. Is their water suppose to stay on their yard even though it's really high?
2. The cutoff trench is a great idea, but I would have to use some type of mechanical removal since it's slope upward towards the ditch on road.

I will have to see what is back there in the drainage easement, hopefully there is a ditch that I can drain that cutoff trench to.

Once again, you guys have great ideas and it's help me to develop a solution, thank you!

 

[r13]

It is not too difficult to dig a V shape ditch. Just maintain good slope, and make sure there is no wash-off from the high ground. Otherwise, leave a bench between the hill and ditch, erosion fabric will help to catch the loose material too.