I have a 5 foot retaining wall in my backyard and a neighbor behind me on about 10 feet higher ground. A lot of their run off goes into my back yard and pools at the base of the retaining wall. I had an "expert" come out and they wanted to put french drains a the higher ground in my backyard as well as at the base of the retaining wall and quoted me about 10 grand as they would have to rebuild the retaining wall.

Wouldn't I solve a large portion of the problem just digging a trench 12" in front of the retaining wall, and installing perforated pipe leading to my side yard. My neighbor has a french drain and I asked if it would be ok it I were to splice into this line leading to the street and he said ok.

My biggest issue is getting the correct slope to be able to tie into his line, but other than that this should be a fairly easy project correct?

* Dig a 12"+ trench for about 30 feet
* Add perforated pipe
* add some liner and limestone
* top with dirt and re-sod

Anyone done anything similar? Is this a 2 day project tops?

We only plan on staying in this house for a few more years and do not want to put a ton of money into it, just enough so the kids and dogs do not track a ton of mud into the house.

I would be very careful not to disturb the ground directly in front of or underneath the retaining wall. If you disturb that compacted soil or base, you could end up with the wall resettling. If you disturb the soil directly in front of the wall, the soil underneath it now has room to expand and squish under the weight of the wall.

I think what you're talking about could be done, but I would personally keep at least 1' between the wall face and the closest edge of the trench. To help redirect water to the drain, you could add a little soil at the base of the wall when you resod and gently slope it towards your drain location. 1/4"/ft should be more than enough.

yeah, i would move away 18" from the wall, it is so swampy now I am afraid the wall will collapse.

I just did this last weekend but only 20'. It took about 6 hours total by myself and wasn't that bad. Worst part was moving all of the excess dirt that you don't fill back in the ditch.

Probably only cost $75. HD sells the perforated pvc for 11$/10' section. Used pea gravel bags for fill and wrapped the pipe with landscaping fabric.

Digging deep enough to get the right slope was a challenge because I ran into a sprinkler line and wound up having to dig like 6+" deeper so I could get the pipe under it.

Did you dig it yourself or use a trencher from home depot?

Dug it myself. I don't think you would need a trencher especially if this area stays wet enough that the ground is relatively soft. Have a friend or two help and you could do it in a day.

Lay down landscape fabric around the gravel, not just the pipe. Otherwise, dirt and silt will eventually just migrate into the gravel, and you'll be left with a pipe in gravely dirt that. You want it really permeable so water readily flows into it and collects in the pipe.

This way the amount of water that can flow through is based on how much can flow onto the gravel and the surface area between it and the surrounding ground. If the gravel fills with soil, then the amount is limited by how much can flow through the soil/gravel into the pipe and basically it becomes the surface area of the perforations.

Is the neighbor's french drain for the same issue?

They only issue I see with tieing into his is it may not be able to handle the additional volume that yours will bring into the equation. What size is his drain to the street ?

It appears to be 4in perforated pipe, I'll know for sure once I start digging