Living shade trees shall be located on each side of the street an average distance of 50 feet apart, but not less than 35 feet nor more than 75 feet apart. The minimum acceptable size for new or existing shade trees shall be two inches to 2 1/2 inches in caliper on property at a height of six inches from the ground. Trees shall be at least eight feet from any sidewalk, curb, gutter and street pavement on the interior or dwelling side thereof, and 10 feet from a line which is directly under any utility lines or wires.