All multiple dwellings which are proposed to be erected or constructed within 200 feet of a proposed or existing freeway right-of-way shall be shielded by a wall or a combination of a wall and earth berm. The composition, extent and nature of the wall or beret and wall shall be sufficient to muffle noise caused by motor vehicles traveling on the existing or proposed freeway, which wall or beret and wall shall be approved by the city’s principal planning and building official. The height of the wall or beret and wall shall be sufficient to intersect a line drawn from a point ten feet above grade at any point along the lane of the proposed or existing freeway nearest to the proposed dwelling to the top of any window in the proposed dwelling.
(`78 Code, § 17.24.210.)