A structure typically constructed of stone, brick, concrete, railroad ties, or similar landscaping timbers, built to contain a bank of earth for the primary purpose of providing improved structural stability of the higher side, preventing subsidence, or preventing water from flooding and causing erosion, and which results in a difference of at least twelve inches (12") between the finished grade on one side of the wall and the finished grade on the other side of the wall, and which is not higher than six inches (6"), including coping, above the highest graded side. [Ord. 1406, 11-10-14.]