Recent Innovations In Virginia Dam Safety & Floodplain Management Program

Transcription

1 Recent Innovations In Virginia Dam Safety & Floodplain Management Program Robert T. Bennett, P.E., R.A., C.F.M. Director Dam Safety & Floodplain Management Virginia Department of Conservation & Recreation

2 Legislation Update Probable Maximum Precipitation Study Orphan Dam Prevention Landowner Liability SWCD Dams

3 Virginia Dam Safety Program Innovations Dam Dragnet Dam First Aid Dam Watch Simplified Inundation Mapping

4 Dam Dragnet Old Definition Regulated Dam 25 feet or greater in height 50 acre feet or greater in capacity

5 Dam Dragnet New Definition Regulated Dam - 25 feet or greater in height - 15 acre feet or greater in capacity - 6 feet or greater in height - 50 acre feet or greater in capacity

6 Dam Dragnet GIS Software USGS National Hydrography Dataset 6,000 water bodies > 1.5 acres area

7 Dam Dragnet Process Avoid duplication by comparing dams in database to water bodies Visually scan aerials to confirm location and area of potentially regulated dams Estimate height from topography Determine ownership from land and tax records

8 Dam Dragnet Process Contact owner Site visit to confirm height and capacity If regulated size, explain requirements In one of 5 regions in Virginia, number of dams increased from 211 to 578

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10 Dam First Aid Trailers equipped with 6 PVC pipe with valves for siphons (2.2 cfs) Trash pump for priming siphon Generator and flood lights Tools and safety equipment

11 Dam First Aid Four trailers located in Virginia State Parks Dam owners must be trained and supervised by Dam Safety Engineers $10,000 for each equipped trailer

12 Dam Watch Real-time, web-based, dam break early warning system Live feeds of NWS warnings, USGS stream gauges, earthquakes Delineated watersheds allow program to total rainfall from NEXRAD data

13 Dam Watch Alerts via , text, fax To dam owners and emergency responders Warnings set at 50 year storm Alerts set at 100 year storm

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17 Dam Watch Service to dam owners Improvement to public safety Cost is free to dam owners State Cost $66 per dam per year

18 Inundation Mapping 1. Code requirement for all regulated dams 2. To determine hazard classification Sunny day dam break Spillway design flood with dam failure Spillway design flood without dam failure Probable Maximum Flood with dam failure

19 3. Emergency Action Plan -Impacts from sunny day dam failure -Impacts from PMP with dam failure 4. Hazard Creep Prevention -Prevent development in inundation zone

20 Simplified Inundation Mapping For Low Hazard Dams Cost Saving Strategies One site visit No field surveys Use DEM Data Simplified models

21 Simplified Inundation Mapping Models used initially: GeoDam Breach DSAT Wise Limited to Sunny Day Failure Models used now: PondPak V8i, HEC-1, HEC-HMS, HEC- GeoRAS, HEC-RAS, ArcMap 10.1

22 Simplified Inundation Mapping Provide Owner: Analysis & Map Determination of Low Hazard or Not What Owner needs to do Next Eligible for Simplified General Permit File Map with Locality to Prevent Development Downstream

23 Simplified Inundation Mapping Time: 2 weeks Cost to Dam Owner $2,000 State Match $2,000

24 Why Innovations? Dam Dragnet Dam First Aid Dam Watch Simplified Inundation Mapping Improve public safety at minimal cost Assist dam owners with challenges Establish relationships between regulators and dam owners

25 National Flood Insurance Program in Virginia 113,219 NFIP Policies $28.1 Billion Coverage $84.9 Million Annual Premiums $749 Average Premium Per Policy Biggert-Waters Flood Insurance Reform Act of 2012 Homeowner Flood Insurance Affordability Act of 2014

26 Floodplain Management Ideas Real Estate Disclosure Act - Floodplains Grants to Localities to Join CRS Reduce Number (288) NFIP Localities Limit to Counties (95) & Cities (41)

27 Questions Recent Innovations In Virginia Dam Safety & Floodplain Management Program Robert T. Bennett, P.E., R.A., C.F.M. Director Virginia Dam Safety & Floodplain Management Program Department of Conservation & Recreation