Help with wood retaining wall?

I'm not really sure where to post this...

My house is right at a corner where a street dead-ends, and an alleyway runs up past our house to the street behind ours.

Our lot is above the street, so at the one corner it slopes down pretty steep along the edge of the alleyway and at some point, a previous owner installed a small wooden retaining wall just to help keep the hillside of slipping into the street.

When we moved into the house the retaining wall was in decent shape, but in the 5 years we have lived here it has been absolutely destroyed, as shown here:


I'm almost positive that the guys that come around here and cut grass (they tow trailers) have been coming up through here, cutting the corner too close and hitting the wall with their trailers. Either them or the FedEx/UPS trucks, I'm not really sure.

At any rate it needs fixed. The 4x4 posts that were originally installed still look good, so I was planning on fixing it with some pressure treated 2x4's between them (which is what it looks like they had done before). However I want to face it with something that will be a little more resistant to damage. Originally they used some kind of thin planks that they placed on it vertically, and I think that was part of the reason it got so torn up. So I'm wondering, would good plywood be a decent face covering for it? Or should I use some metal sheeting? I'm afraid metal will rust very quickly though.

 

Unfortunately any wood retaining wall is going to have a limited lifespan. If you want it to last I would suggest considering something more permenant like pre-cast concrete engineered retaining wall blocks or a built up or solid poured concrete retaining wall.

If you want to do a Band-Aid with wood most 2"x treated lumber is not treated for ground contact unless you live near the coast. You can special order 2"x lumber that is treated for ground contact and it will last longer but will be more expensive. If you want to face the wall I would use 2"x lumber. It will hold up much better than pressure treated plywood.

 

I did not know treated lumber was not treated for ground contact. I guess it will be kind of a band-aid, I'm not sure who did the wall originally but the 4x4 posts are driven into the ground. I may look into other options, I just need something to make sure the hill doesn't slip.

 

Most pressure treated 4x4s and 6x6s are rated for ground contact but most of the other treated wood is not. I'm partial to having a masonry wall [block,brick, stone, etc] because that takes away the rot factor.

 

Maybe railroad ties, stacked 2 or 3 high and held in place with one inch by 3 foot steel pipe......??

 

I have a tiered RR tie wall just inside my goat's fence. What I did was drill a hole thru the RR ties and pound rebar thru them. It's held up good over the last 10 yrs or so.