This video shows a sharp cliff near my house that leads down to a stream. The drop is about 20 feet. I would like to build a 4' high retaining wall right around where you see a stack of dead branches. We'll be about 10' away from the stream and about 6' up. The wall would be facing SW.
I have consulted with a contractor and he advised me that it's a bad idea to use treated railroad ties in an under a canopy of trees for fear of rot. However, I have a neighbor with a beautiful railroad ties retaining wall that's been there for 30 years and looks pristine. Furthermore, the lumber steps that you see are 75 years old and for 30 of those years were covered with leaves and overgrowth and the steps are still in passable shape.
What's your take on it? Am I safe using treated lumber to build a wall there?