I have a small backyard that ends off with a steep slope which leads to some sort of sewer / creek at the bottom. I have already gotten a wooden wall built behind my porch, which is now separating from the foundation of the house. Apparently that wooden wall wasn't enough and now the dirt next to the wall is starting to wash away into the ditch. I'm thinking about putting up a retaining rock wall but then, I am also concerned if the retaining rock wall will be washed down into the ditch after a couple of rain showers. What should I do about this problem before my entire house washes away?

amricca

Best thing would be to plant some grass that will keep the soil in place. Boulders are also a good way to retain without having to build footings for a wall.

loricar

terracing, either with wood spikes set deep, or better, rock retaining walls. Quickie method would be landscape fabric to stop the water erosion. Combination of methods for short and longterm solutions, and if all else fails get a landscape architect quick!
good luck
loricar

smearcase

Not knowing exactly what the situation is. the only suggestion I have is to stabalize the slope with an excelsior matting type material, which consists of fiberglass netting which sandwichs a wood fiber or other biodegradeable material. Grass seed is planted before the matting is applied, and when the grass comes up it grows thru the matting and becomes very sturdy. This works well on steep highway slopes.
It is very important to have the backyard drain well. I dont think you want to try to protect the slope by slowing the flow of water away from the house. If you do retaining wall type structures you need drains to take the water away from the house side of the wall.

smokedetector

You mean the wall is in place still and the dirt is slipping through the cracks or something? If this is the case, put a piece of landscaping plastic/fabric between the dirt and wall.

If the wall is not holding, you can try repairing it by putting pieces of rebar in the ground as staves. Go at least as deep as the height of your wall, and space them at least every few feet.