Wake County Hazard Mitigation Plan - January 2020

SECTION 4: RISK ASSESSMENT

Max Capacity (Ac-Ft)

Condition as of Last Inspection

Nearest Downstream Location

Dam Name

NID ID

Crabtree Creek W/S #1 (PL-566) Crabtree Creek W/S Dam #18 Breckenridge Recreation Center Dam Breckenridge Tract 9 & 10 Dam Rolesville none Wake Forest Brown Lake Dam (AKA St. Andrews Plantation WAKE-268)

NC01449 NC01453 NC05622 NC05623

Satisfactory Satisfactory Satisfactory Satisfactory

480 661

Raleigh

Morrisville

38 83

Cary Cary

NC00859

Fair

52

Milburnie

Milburnie (S. Franklin St @ Dam

Holding Lake Dam

NC00873 NC04439

Satisfactory Not Rated

145

Lewis Dam

80

Wake Forest

Milburnie (WaitAve(NC- 98)(.12)

Wake Forest Water Supply Dam St. Andrews Plantation Dam

NC00995 NC04579

Satisfactory

945

Fair

23

Coach Lantern Ave

Wendell Timberlake Dam

NC05843

Fair

9999

Cedarmere Drive

Zebulon none Source: North Carolina Dam Inventory, July 2018

Extent Each state has definitions and methods to determine the hazard potential of a dam. In North Carolina, dams are regulated by the state if they are 25 feet or more in height and impound 50 acre-feet or more. Dams and impoundments smaller than that may fall under state regulation if it is determined that failure of the dam could result in loss of human life or significant damage to property. The height of a dam is from the highest point on the crest of the dam to the lowest point on the downstream toe, and the storage capacity is the volume impounded at the elevation of the highest point on the crest of the dam. Dam Safety Program engineers determine the "hazard potential" of a dam, meaning the probable damage that would occur if the structure failed, in terms of loss of human life and economic loss or environmental damage. Dams are assigned one of three classes based on the nature of their hazard potential:  Class A (Low Hazard) includes dams located where failure may damage uninhabited low value non-residential buildings, agricultural land, or low volume roads.  Class B (Intermediate Hazard) includes dams located where failure may damage highways or secondary railroads, cause interruption of use or service of public utilities, cause minor damage to isolated homes, or cause minor damage to commercial and industrial buildings. Damage to these structures will be considered minor only when they are located in backwater areas not subjected to the direct path of the breach flood wave; and they will experience no more than 1.5 feet of flood rise due to breaching above the lowest ground elevation adjacent to the outside foundation walls or no more than 1.5 feet of flood rise due to breaching above the lowest floor elevation of the structure.  Class C (High Hazard) includes dams located where failure will likely cause loss of life or serious damage to homes, industrial and commercial buildings, important public utilities, primary highways, or major railroads.

Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019

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