The surveyor must at the time of making the survey, set in such manner that they will not be moved by frost, good and sufficient monuments marking the external boundaries of the tract to be divided and must designate upon the plat the points where they may be found. These monuments must be placed at all corners, at each end of all curves, at the point where a curve changes its radius, at all angle points in any line and at all angle points along a meander line, the points to be not less than twenty (20) feet back from the normal water elevation of a lake or from the bank of a stream, except that when such corners or points fall within a street, or proposed future street, the monuments must be placed in the right of way line of the street. These monuments, two of which must be of reinforced concrete and set at opposite extremities of the property platted. All lot corners shall be monumented in a like manner with iron pins or pipe.
Concrete monuments shall be in accordance with State Plat Act.