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The North Carolina State Dam Safety Program

The North Carolina State Dam Safety Program. http://portal.ncdenr.org/web/lr/dams By: Tami Idol, EI Tami.Idol@ncdenr.gov. Let’s start with the basics What is the Mission of the Dam Safety Program? To prevent property damage, personal injury and loss of life from the failure of dams.

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The North Carolina State Dam Safety Program

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  1. The North Carolina State Dam Safety Program http://portal.ncdenr.org/web/lr/dams By: Tami Idol, EI Tami.Idol@ncdenr.gov

  2. Let’s start with the basics What is the Mission of the Dam Safety Program? To prevent property damage, personal injury and loss of life from the failure of dams

  3. Dams Provide Benefits: • Water Storage for Municipal and Industrial Use • Cooling Water for Thermal Power Plants • Flood Reduction • Hydroelectric Power • Minimum Flows to dilute sewage treatment plant discharge • Storm Water Treatment • Irrigation Water Storage • Animal Waste Storage and Treatment • Recreation

  4. Negative Effects of Dams: • Environmental Alteration in the Impoundment • Environmental Alteration Downstream • Displacement of People • Loss of Cultural and Historical Resources • Expensive to Construct • Expensive to Maintain • Hazard Potential for People and Property Downstream

  5. Jurisdictional Dams • If Dam is 25 Feet in Height or Greater as Measured from the Highest Point on the Crest of the Dam to the Lowest Point on the Downstream Toe, AND • If the Dam has an Impoundment Capacity of 50 Acre-Feet or Greater as Measured at the Highest Point on the Crest of the Dam

  6. Jurisdictional Dams – High Hazard Potential • If Failure of the Dam Could Result in Loss of Human Life or Significant Damage to Property Below the Dam regardless of height or impoundment capacity. GS 143-215.25A (a)(6)

  7. How is the Dam Safety Program Organized?7 DENR Regional Offices (RO), 1 Raleigh Central Office (RCO) Staffing: 9 FTE’s in the RO’s and 9 FTE’s in the RCO 49 LQS regional staff are cross trained for Dam Safety, Sediment and Erosion Control, and Mining

  8. The Dam Safety Program carries out its mission through Four Basic Functions designed to ensure Safe Dams (IREE): • We Perform Dam Inspections • We Review and Issue Construction Approvals • We Carry Out Enforcement Actions • We Assist with Emergency Response

  9. State-wide Jurisdictional Inventory12-31-2011 • 1,118 - High Hazard Dams • 245 - Intermediate Hazard Dams • 622 - Low Hazard Dams • Grand Total - 1,985 Dams • Includes Low and Intermediate hazard dams 25 feet in height or larger and 50 acre-feet of maximum impoundment capacity or larger • Includes high hazard dams of any size

  10. What would you do?

  11. Well… yes, sometimes Do Dams Fail in NC?

  12. Historic Dam Failures in North Carolina

  13. Lake Toxaway Dam – 1916Transylvania County • After days of heavy rain from tropical systems, the original Toxaway Dam failed on August 13, 1916. Over 16,000 acre-feet (5.2 Billion Gallons) of water scoured the gorge downstream to bedrock. • There was no known loss of human life. Property damage, however, was extensive.

  14. Bearwallow Dam Failure

  15. Bearwallow Dam FailureBuncombe County • Failed February 22, 1976 • Approximately 30 feet high with a 3.5 acre lake • Resulted in Four Deaths • There was apparently no engineering supervision during construction of the dam • Dam was unknown to regulators prior to failure • Resulted in the expansion of the Dam Safety Program

  16. Roxboro Reservoir DamPerson County Municipal water supply dam Failed March 7, 1984, as a result of internal erosion (piping) under the concrete chute spillway Resulted in loss of a 280 acre reservoir and a highway bridge No loss of life

  17. Roxboro Dam Failure

  18. 1989 Evans and Lockwood Dam Failures (Fayetteville) • Several dams in series failed. • They were unknown to DLR at that time as they were below jurisdictional size • Loss of life (2 children) and property damage resulted • As a result of this event, legislation was passed that rendered all high hazard dams jurisdictional regardless of size (remember the 1989 amendment?)

  19. Damage to Dams, Fall 1999 (Floyd) • More than 100 jurisdictional dams had some damage. • 35 dams failed. • 16 high hazard dams failed. • There was no loss of life attributed to the dam failures.

  20. Damage to Dams from Frances and Ivan 2004 • One failure of a high hazard dam, no loss of life or property damage but a road was overtopped. • Three high hazard dams damaged so severely they had to be drained and breached. • Two dams undergoing repairs were damaged. • One failure of a jurisdictional low hazard dam • Several small non-jurisdictional dams failed. • Damage to remaining 300 plus high hazard dams inspected was relatively light, none requiring that the impoundments be drained.

  21. Hope Mills DamCumberland County Municipal recreation dam Construction completed April, 2009 Failed June 17, 2010, as the result of a foundation cutoff failure Resulted in loss of reservoir and extensive spillway damage No loss of life Ironically, this structure was installed as repair for failure of the original dam in 2003

  22. Hope Mills Dam

  23. Hope Mills Dam

  24. Hope Mills Dam

  25. Hope Mills Dam

  26. Hope Mills Dam

  27. Hope Mills Dam

  28. Hope Mills Dam

  29. Hope Mills Dam

  30. Background of Emergency Action Planning for Dams • Since 9/11, requirements by FEMA have increased priority toward EAPs • EAPs are not required by law in NC • In order to meet FEMA requirements, NC dam safety staff are requesting owners of high hazard dams to have an EPA. Often times this means working 1 on 1 with each owner.

  31. ARE WE DOING IT RIGHT?WE NEED YOUR INPUT!!!!!

  32. EMERGENCY RESPONSE

  33. Emergency Response • NC Dam Safety staff Role: • Counsel local Incident Commanders as to level of emergency in a dam incident situation • Assist with interpretation of the EAP (if one exists) • Advise the Local Incident Commander concerning the need to evacuate • Assist owner of dam and local responders in preparing an EAP • All Dam Safety RCO staff are SERT (State Emergency Response Team) members: • Serve in the infrastructure discipline • Man the state Emergency Operations Center (EOC) when it is activated during any situation which may threaten dams • All LQS staff are on duty 24-7 in the event of a dam emergency • 18 two-person inspection teams from the RO’s available • Plus RCO staff rotates on 8 to 12 hours shifts at the EOC during activation

  34. FEMA requires all states to adhere to: National Incident Management System (NIMS) Incident Command System (ICS)

  35. ImplementDocument Procure Pay & Audit

  36. Emergency Operation Center800-858-0368

  37. Emergency Action Plans (EAPs) • An Emergency Action Plan (EAP) outlines procedures to minimize risks to life and property when the integrity of a dam may be in jeopardy.  • Two parts to the EAP equation: • The EAP shall consider all potential emergency situations, both natural and manmade. Owners & engineers responsibility • shall identify appropriate responses. Local responders responsibility

  38. Planning, Training, and ExercisesAll Hazard focused plansCollaborationPractice and experience

  39. Collaboration • Collaboration between NC Dam Safety and NC Emergency Management , Flood Plain Mapping Program: • Producing a web based fill in the blank EAP for owners based upon the current template. • Flood mapping may be completed by the owners engineer or • based upon a risk assessment, one of 3 levels of analysis, Bronze, Silver or Gold level mapping will be completed through collaboration and provided to responders.

  40. BRONZE Example Vicinity Map

  41. SILVER • Medium risk high hazard dams • Possibly using a method recently beta tested by NC Dam Safety and NCFPMP • This method produces a GIS shapefile, just like the GOLD level would, with slightly less effort in data collection and input. This output will show more structures in the flooded area than a more detailed analysis.

  42. GOLD • High risk high hazard dams • Using a full scale HEC RAS analysis. • This method produces a GIS shapefile as well. With more detail and effort going into data collection, the results will be closer to what reality would be.

  43. GIS Capability Open Troublesome Creek EAP maps

  44. What does the Dam Safety program need?

  45. We need more EAP’s • EAP’s for high hazard dams !!!!! • Only 32% of high hazard dams in NC have EAP’s on file today • The problem - No statutory authority to require them • How do we procure them now? • Through requests to dam owners • By stipulation in approvals • Local responders could be invaluable in getting the ball rolling • Nothing is more valuable during a dam incident • Emergency Management uses the EAP to develop evacuation plans

  46. Estimated 450 fatalities 1200 buildings destroyed or damaged 24,000 acres of agricultural land destroyed St. Francis Dam - 1928

  47. Teton Dam 11:20 AM June 5, 1976

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