Design and Maintenance Requirements

Design and Maintenance Requirements. A. Any modification, alteration, enlargement, or major repair of an existing dam, whether requested by the owner or directed by the Commission, will be subject to the current design standards for the appropriate hazard classification as set forth in this regulation. B. High Hazard dams must be capable of safely passing the runoff from a 24 hour duration 100-year rainfall event through the principal spillway without activating the auxiliary (emergency) spillway. The 100- year rainfall event is established by the National Weather Service Atlas 14 and varies for different areas of the state. The runoff from one hundred percent (100%) of the 24 hour Probable Maximum Precipitation (PMP), as defined in