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Virginia Department of Virginia Department of Conservation & RecreationConservation & Recreation
Virginia Dam Safety & Floodplain Programs
William G. Browning, DirectorDam Safety & Floodplain Management
Dam Safety & Floodplain Dam Safety & Floodplain OrganizationOrganization
• Department reorganization effective November 1, 2003
• Merged Dam Safety and Floodplain Management Programs
• Purpose is to reduce risks and hazards to the Commonwealth from dam failure and floods.
Dam Safety & Floodplain Dam Safety & Floodplain OrganizationOrganization
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Virginia Dam Safety Act of Virginia Dam Safety Act of 1982; Amended July 1, 20021982; Amended July 1, 2002
• Provides for the proper and safe design, construction, operation and maintenance of impounding structures to protect public safety.
• No impounding structure can ever be completely fail-safe, because of incomplete understanding of/or uncertainties
associated with natural and man-made destructive forces
material behavior and responses to those forces quality control during construction
Code of Virginia Requirements:Code of Virginia Requirements: The law regulates impounding structures
including dams used to retain or store waters or other materials. With a few exceptions, the following structures are regulated:
> Impounding structures 25 feet or higher with a maximum impoundment capacity of 15 acre-feet or more
> Impounding structures 6 feet or higher with a maximum impoundment capacity of 50 acre-feet or more
Definitions:Definitions:
Dam height is the vertical distance from the streambed at the downstream toe to the top of the dam.
Maximum Impounding Capacity of a dam is the volume capable of being impounded at the top of the dam.
Acre-foot is a volume of one foot of depth over one acre of area
50 acre-feet
6’-25’ high
15 acre-feet
25’ or higher
Classifying Regulated DamsClassifying Regulated Dams
• Impounding structures are classified by hazard potential and size
• Hazard potential relates to downstream losses that may occur if the dam fails
Classes of Hazard Potential If Classes of Hazard Potential If Structure FailsStructure Fails
Class I Probable loss of life
Excessive economic loss II Possible loss of life
Appreciable economic loss III No loss of life expected
Minimal economic loss IV No loss of life expected
No economic loss to others
Performance Standards Required Performance Standards Required
for Impoundments*for Impoundments* The required spillway
design flood is based on the combination of :
• hazard classification • size classification
* 4 VAC 50-20-50
Classifications of DamsClassifications of DamsClass Dam Size Spillway Design Flood
I LargeMediumSmall
Probable Maximum Flood (PMF)
PMF
½ PMF to PMF
II Large
Medium
Small
PMF½ PMF to PMF100 Year to ½ PMF
III Large
Medium
Small
PMF100 Year to ½ PMF50 Year to 100 Year
IV Small 50 Year to 100 Year
Documents Required For Documents Required For Certification:Certification:
Operation and Maintenance Application – I, II & III
Emergency Action Plan - I, II & IIIRe-inspection Report – I & IIInventory Report – III & IV
Note: Class IV inventory report can be completed by owner
Frequency of SubmittalFrequency of Submittal
Class Plan and Report Schedule
I Operation and Maintenance Plan – 6 year intervalRe-inspection report - 2 year interval
II Operation and Maintenance Plan – 6 year intervalRe-inspection Report – 3 year interval
III Operation and Maintenance Plan – 6 year intervalInventory report – 6 year interval
IV Inventory report - 6 year interval.
In addition…In addition…
Owners of Class I, II, III and IV structures shall perform an annual owner’s inspection and submit the report in years when a professional re-inspection is not required.
Upon Submission of Forms…Upon Submission of Forms…
Dam Safety RegionalEngineers: Review submitted
materials May inspect structure Make recommendations
to the Soil and Water Conservation Board
The Soil and Water Conservation The Soil and Water Conservation Board Issues:Board Issues:
• Regular Operation And Maintenance Certificates
• Conditional Operation And Maintenance Certificates
• Construction Permits for new dams• Alteration Permits to repair and/or
upgrade dams• Transfer of Ownership
Regional Engineers Also …Regional Engineers Also …
• Review new construction and alteration applications
• Advocate dam safety to local governments
• Respond to emergencies• Provide training
Number Of Impoundments Number Of Impoundments In DatabaseIn Database
Conditional Regular Being Built
Total Regulated
Non-Regulated*
Total
I 29 79 4 112 43 155
II 13 111 10 134 159 293
III 10 227 12 249 906 1155
IV 0 24 2 26 0 26
*May need permitting based on regulation criteria change July 1, 2002
Types of Non-Regulated DamsTypes of Non-Regulated Dams
Certification Type
I II III IV Total
Agricultural Exemption
1 8 86 0 95
Federal License 29 18 67 0 114
Mining Exemption
5 5 10 0 20
Size Exemption 8 128 741 2 879
Why Does Dam Safety & Floodplain Why Does Dam Safety & Floodplain Management Matter?Management Matter?
• At least 18 declared flood or hurricane disasters since Hurricane Camille in 1969
• Timberlake dam failure killed 2 people
• Flooding is the most costly and frequent Virginia natural hazard
Hurricane Floyd – September 1999Hurricane Floyd – September 1999
• 13 dam failures in eastern Virginia
• Devastated Southampton County and Franklin
• Floodwaters did not receed for 11 days
How Do We Prevent Damage From How Do We Prevent Damage From Floods and Hurricanes?Floods and Hurricanes?
• Through Proper Dam Maintenance
• Build At or Above The Base Flood Elevation
• Elevate, Relocate or Demolish Flood-prone Structures
• Conserve Floodplains for Habitat, Open Space, Flood Capacity and Storage
Dam Safety & Floodplain Dam Safety & Floodplain Management Programs Management Programs
Need Your Help…Need Your Help…
Please Contact Us RegardingPlease Contact Us Regarding
• Use of Downstream Inundation Zones • Training In Floodplain Management &
Dam Safety • Floodplain Ordinance Review• Technical Assistance For Dams &
Floodplain Construction• Floodplain Management Community
Assistance Visit• Dams 6 Feet or Higher That Are Not
Properly Maintained
Contact InformationContact Information
Department of Conservation & Recreation
Dam Safety and Floodplain Management Programs
203 Governor Street, Suite 206Richmond, VA 23219
804-371-6095www.dcr.state.va.us