Any finish grades on any lot or dedicated public area which are steeper than one on three shall be protected by either sodding or by the construction of a retaining wall of approved design. Any finish grade steeper than one on two shall be protected by a retaining wall of approved design. All such retaining walls shall meet the requirements specified in the Building Code. All such sodding shall comply with M.D.S.H. Standard Specifications, Designation 6.21, Sodding, Class A, as amended.