Level 2, YELLOW Emergency - Potential dam failure situation, rapidly developing This classification indicates that a situation is developing that could lead to dam failure, but there is not an immediate threat of dam failure. The dam Owner/Operator should closely monitor the condition of the dam and periodically report the status of the situation. A reasonable amount of time is available for analysis before deciding on evacuation of residents. If the dam condition worsens and failure becomes imminent, the Incident Commander must be notified immediately of the change in the emergency level to evacuate the people at risk downstream. If time permits, the Owner’s Engineer and state dam safety officials should be contacted to evaluate the situation and recommend remedial actions to prevent failure of the dam. The dam operator should initiate remedial repairs (note local resources that may be available—see Appendix C). Time available to employ remedial actions may be hours or days. Level 3, GREEN Unusual Event - Slowly developing This classification indicates a situation is developing, but has not yet threatened the operation or structural integrity of the dam. The Owner’s technical representative or engineer AND NC Dam Safety Office should be contacted to investigate the situation and recommend actions to take. The condition of the dam should be closely monitored, especially during storm events, to detect any development of a potential or imminent dam failure situation. See the following pages for guidance in determining the proper emergency level for various situations. EMERGENCY LEVELS top tab inserted Replace Page with divider Table 1.3 Emergency Level Determination & Action Data Sheet Index Action Data Emergency Event Condition level* Sheet Unexpected Dam unexpectedly and without warning begins to fail Failure Reservoir water surface elevation at auxiliary spillway crest or spillway is flowing with no active erosion Earth spillway Spillway flowing with active gully erosion or flow that could result in flooding flow of people downstream if the reservoir level continues to rise Spillway flowing with an advancing head cut that is threatening the control section or that is already flooding people downstream Reservoir is 1 foot below the top of the dam Embankment overtopping Water from the reservoir is flowing over the top of the dam New seepage areas in or near the dam, water flowing clear Seepage New seepage areas with cloudy discharge or increasing flow rate Seepage with discharge greater than 10 gallons per minute Observation of new sinkhole in reservoir area or on embankment Sinkholes Rapidly enlarging sinkhole
Level 2, YELLOW Emergency - Potential dam failure situation, rapidly developing This classification indicates that a situation is developing that could lead to dam failure, but there is not an immediate threat of dam failure. The dam Owner/Operator should closely monitor the condition of the dam and periodically report the status of the situation. A reasonable amount of time is available for analysis before deciding on evacuation of residents. If the dam condition worsens and failure becomes imminent, the Incident Commander must be notified immediately of the change in the emergency level to evacuate the people at risk downstream. If time permits, the Owner’s Engineer and state dam safety officials should be contacted to evaluate the situation and recommend remedial actions to prevent failure of the dam. The dam operator should initiate remedial repairs (note local resources that may be available—see Appendix C). Time available to employ remedial actions may be hours or days. Level 3, GREEN Unusual Event - Slowly developing This classification indicates a situation is developing, but has not yet threatened the operation or structural integrity of the dam. The Owner’s technical representative or engineer AND NC Dam Safety Office should be contacted to investigate the situation and recommend actions to take. The condition of the dam should be closely monitored, especially during storm events, to detect any development of a potential or imminent dam failure situation. See the following pages for guidance in determining the proper emergency level for various situations. EMERGENCY LEVELS top tab inserted Replace Page with divider Table 1.3 Emergency Level Determination & Action Data Sheet Index Event Condition Emergency level* Action Data Sheet Unexpected Failure Dam unexpectedly and without warning begins to fail Earth spillway flow Reservoir water surface elevation at auxiliary spillway crest or spillway is flowing with no active erosion Spillway flowing with active gully erosion or flow that could result in flooding of people downstream if the reservoir level continues to rise Spillway flowing with an advancing head cut that is threatening the control section or that is already flooding people downstream Embankment overtopping Reservoir is 1 foot below the top of the dam Water from the reservoir is flowing over the top of the dam Seepage New seepage areas in or near the dam, water flowing clear New seepage areas with cloudy discharge or increasing flow rate Seepage with discharge greater than 10 gallons per minute Sinkholes Observation of new sinkhole in reservoir area or on embankment Rapidly enlarging sinkhole