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AKA: ~
Location: Rehoboth, Delaware
Additional Information: The wall pictured is made from railroad ties soaked in coal tar creosote. Although coal tar creosote is an EPA approved wood treatment and remains the most widely used wood preservative in the world it is not recommended for retaining walls. The reason for this is that leaching CTC can be harmful to plants, animals and humans.
It seems logical to me that the large surface area of a wood retaining wall in direct contact with soil would make for a heck of a lot of leaching.
The example wall also looks to have had 4 x4 braces applied to its face to maintain its integrity. Closer inspection shows the brace on the right is bent and splitting from outward force at the fastener.
While all wooden retaining walls will eventually fail, proper drainage can help keep timbers dry and extend a walls life.
Relative Link: Build a wood retaining wall
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