Active job

Low retaining walls

I currently have a "retaining wall" for the garden which is 3 tyres high and 50m long or so. I want to remove all the tyres (while saving the plants that have been planted in them) and replace them with a treated timber retaining wall of an equivalent height. In addition, there is a farm gate on a slope which has too large a gap under it which I would like some sort of retaining wall structure built under it so I can back fill behind it - need to stop the sheep escaping.