Trees produce extensive root systems that spread out and down from the base of the stump. These roots can remain active for long periods of time, causing the stump to produce new shoots with green foliage for several years after you cut down the tree.he exact amount of time it takes a stump to decay varies depending on the species of tree and the conditions in your yard. If you do not want to wait, there are ways you can encourage a stump to break down on your schedule instead of nature's.
1 Materials and installation for a stone retaining wall start around $25-$40 a square face foot and go up depending on materials, site conditions, and other factors. 2  It costs $1,250-$2,000 or more for a wall 30 inches high and 20 feet long.
Wood Retaining Wall Prices. Wooden retaining walls start at around $20 per square foot including materials and installation if using cost-effective pressure treated lumber. Hardwoods such as redwood, Cyprus or mahogany will raise the price over $30 per surface square foot but add an element of beauty to your wall.Railroad ties are the most commonly used wood for a retaining wall, and prices for this type of wall cost between $25 and $30 per square foot of wall.tone Retaining Wall Prices. Stone retaining wall costs typically start around $5 to $10 per surface square foot of wall. They can reach higher if a specific type of stone is used.