My parents have an old retaining wall (30+ years?) that needs to be replaced. They are open to any kind of materials, it doesn't need to be wood. What is the easiest way to build a new retaining wall that lasts about as well as this old one? It is about 4.5 feet high and 18 feet long. No problems over the years. Most of the plans I have found online (like this http://www.mrgrow.com/Tips/98/tip04.htm ) are for new walls, and seem to involve a TON of digging. I'd also consider regrading this if it makes sense.
Any properly designed and built retaining wall involves some quantity of digging. For a timber retaining wall, there is extra digging for the deadmen. If you were to replace that wall with timber, you'd have to do a lot of digging. But materials would be cheap. If you were to replace with stacking wall units, you'd still have to dig a sound base, and dig out enough room behind it for the gravel, fabric, drain and stone. If you're doing it yourself, stacking wall units are probably easier.