R655-11-10B. Survey Markers and Bench Marks

All moderate and high hazard dams shall have permanent survey markers on the crest of the dam to monitor vertical and horizontal movement. The survey markers should be located to prevent damage from traffic. In conjunction with the survey markers a permanent bench mark shall be installed on each abutment, sufficiently removed from the dam so any effects of the dam movement will not be felt at the bench mark. Reference markers should be established so the bench mark can be reset in the event of damage. Spacing of survey markers should not exceed 200 feet and spacing should be decreased as the height of the dam increases.