(a) Concrete posts measuring six (6) inches by six (6) inches by 48 inches with one- half (1/2) inch iron road cast in the center shall be placed on each corner of the boundary of the subdivision as follows:
(1) At the centerline intersections of all roads.
(2) At the P.C. and the P.T. of all curves on the centerline of the road and on all lot lines.
(3) At all angle points.
(4) Other points as are necessary to establish definitely all lines of the plat.
(b) Permanent iron pins, at least 30 inches long and three quarters (3/4) of an inch in diameter, or similar suitable marker shall be placed at all corners of each lot. Any contractor or persons doing preliminary of final grading, or ground work of any kind, shall be responsible for the preservation of all such markers.
(c) Street monuments shall be set in suitable monument boxes.