Walls, fences and berms required under this chapter shall have no openings for vehicular traffic or other purposes, except such openings as may be approved by the Commission. All walls required in this Chapter shall be constructed of stone, brick or shall have brick veneer on the side facing the residential district. The height of the wall shall be measured from the prevailing grade of the land on the residential side of the wall or berm. Walls shall be erected on a concrete foundation which shall have a minimum depth of 42 inches below a grade approved by the Administrative Official and shall not be less than four inches wider than the wall to be erected.