1	The Delaware Dam Safety Program February 2007
2	National Dam Safety Program Several significant dam failures in western US in early 1970’s National Dam Inspection Act – 1972 90,000 non-federally owned dams across the US were inventoried in the early 1970’s 9,000 dams were inspected between 1978 and 1981 In early 1980’s about half the states had no dam safety laws or programs Association of State Dam Safety Officials (ASDSO) organized in 1984 National Inventory of Dams (NID) maintained by the US Army Corps of Engineers since 1986 As of 2004, all states except Alabama and Delaware had state dam safety laws and/or programs
3	National Dam Safety Program Guidance from ASDSO and Federal agencies: Model dam safety law and program Design, construction and inspection of dams Hazard potential classification Emergency action planning Risk-based analysis Training for program staff
4	Delaware Dam Safety Program – 1970’s Dams inventoried by DNREC and UD in 1974 Dams meeting criteria in the National Dam Inspection Act were reported to the Corps of Engineers: Dam height of 25 feet or greater Impounding capacity of 50 acre-feet or greater Exclusions: dams less than 6 feet high or with a storage capacity less than 15 acre-feet
5	Delaware Dam Safety Program – 1970’s Results of 1974 Inventory New Castle County 14 significant dams 46 small dams Kent County 18 significant dams 3 small dams Sussex County 25 significant dams 9 small dams Statewide totals 57 significant dams 58 small dams
6	Delaware Dam Safety Program – 1980’s National Inventory of Dams (NID) Delaware completed in 1981 Performed by the Corps of Engineers with assistance from State agencies 96 dams were inventoried 14 Dams had Phase 1 Inspection Reports prepared NID data updated several times since 1981
7	Current Delaware NID
8	Delaware Dam Safety Program – 2000’s
9	Delaware Dam Safety Program – 2000’s 2003 report by UD WRA Model dam safety law and program for Delaware State dam inventory was updated using GIS
10	Delaware Dam Safety Program – 2000’s Delaware Dam Safety Law Passed by the legislature and signed by Governor Minner in 2004 Contingent on funding (not funded until FY 2006) Requires that DNREC establish a Dam Safety Program for the State and promulgate regulations
11	Delaware Dam Safety Law “It is the purpose of this chapter to provide for the proper design, construction, operation, maintenance, and inspection of dams in the interest of public health, safety, and welfare, in order to reduce the risk of failure of dams and to prevent injuries to persons, damage to downstream property and loss of reservoir storage.”
12	Delaware Dam Safety Law Criteria for regulation: Public ownership and High or significant hazard potential or Dam height greater than 25 feet Maximum storage capacity greater than 50 acre-feet Exclusions: Dam height less than 6 feet (even if the storage capacity is greater than 50 acre-feet) Dams with storage capacity less than 15 acre-feet (even if the dam height is greater than 25 feet) Dams with low hazard potential
13	Hazard Potential Classifications High hazard potential dam shall mean any dam whose failure or mis-operation will cause probable loss of human life Significant hazard potential dam shall mean any dam whose failure or mis-operation will cause possible loss of human life, economic loss, environmental damage, disruption of lifeline facilities, or can impact other concerns Low hazard potential dam shall mean any dam whose failure or mis-operation is unlikely to cause loss of human life but may cause minor economic and/or environmental losses
14	Delaware Dam Safety Law Existing dams Operation and Maintenance Plan Regular inspections Construction of new dams and repair, alteration or removal of existing dams Construction permit Review and certification of construction by a PE with related experience in dam design and construction Certificate to impound water Operation and Maintenance Plan Emergency Action Plan Regular inspections
15	Draft Dam Safety Regulations Emergency Action Plans required for all regulated dams Hazard classification potential must be determined by dam breach analysis Inspection frequency High hazard dams inspected annually by the owner and every 3 years by a PE and DNREC Significant hazard dams inspected every 2 years by the owner and every 6 years by a PE and DNREC Spillway design storm events High hazard potential – PMP Significant hazard potential – ½ PMP
16	PMP and PMF Probable Maximum Precipitation means the theoretically greatest depth of precipitation for a given duration that is physically possible, over a given size storm area, at a particular geographic location, at a certain time of year. Probable Maximum Flood means the most severe flood considered possible in a specific region based on the PMP, as determined by the National Weather Service
17	Rainfall Extremes in the US
18	Current DNREC Dam Safety Program Activities Dam Safety Regulatory Advisory Committee is assisting DNREC with development and promulgation of Dam Safety Regulations State Dam Inventory Update Verify/update information in our current dam inventory Determine list of regulated dams Perform limited hazard potential assesment Create database for managing dam information Perform risk-based analysis for portfolio of dams to help prioritize rehabilitation needs Expected completion May 2007
19	Update and Verify Delaware Dam Inventory Desktop data collection Dam ownership verification Field data collection Database development Hazard potential assessment Develop list of regulated dams Risk assessment and prioritization of dams for rehabilitation Expected completion - May 2007
20	Delaware State Dam Inventory Current Statistics Overall 172 dams on the inventory 61 dams on the NID Ownership 72 publicly owned 49 privately owned 52 ownership not determined Hazard Classification 9 high hazard potential 27 significant hazard potential 52 low hazard potential 83 hazard potential not determined Regulation Status 37 probable regulation 67 probable non-regulation 68 regulation status not determined
21	Delaware State Dam Inventory Current High Hazard Potential Dams Cool Spring Reservoir - NCC Edgar M. Hoopes Dam - NCC Edgemoor Reservoir - NCC Haven Lake Dam - KC Millsboro Pond – SC Porter Reservoir – NC Records Pond – SC Silver Lake Milford – KC Wagamons Pond - SC
22	Delaware State Dam Inventory Current Significant Hazard Potential Dams
23	Current Dam Safety Evaluation/Rehabilitation Projects Records Pond Dam Safety Evaluation Funded FY04 Evaluation completed 2005 Design 95% complete Construction expected Summer 2007 Chipmans Pond Dam Safety Evaluation Dam safety portion funded FY04 DelDOT subsequently decided to re-align roadway Dam safety evaluation completed 2005 Design completed 2006 Construction funding uncertain Haven Lake and Silver Lake Dam Safety Evaluations Funded FY05 Consultant hired Evaluation to be completed May 2007
24	Records Pond Dam - Laurel
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26	Chipmans Pond Dam - Laurel DelDOT road improvement/DNREC dam safety project Bridge and spillway replacement Road realignment Overtopping protection on embankment Design complete, construction not yet fully funded
27	Haven Lake and Silver Lake - Milford
28	Haven Lake and Silver Lake Dam Safety Evaluations Phase I underway – Evaluation and Analysis Expected completion - May 2007 Scope includes: Inspection reports Topographic survey Hydrologic analysis including development of the Probable Maximum Precipitation (PMP) and the Spillway Design Flood (SDF) Geotechnical and structural evaluations Analysis of alternatives and recommendations for bringing Haven and Silver Lake dams into compliance with our Dam Safety Regulations including construction of new spillways, armoring the embankments to allow safe overtopping, raising the dam to prevent overtopping, or some combination of these alternatives. Phase II – Design and Permitting Phase Phase III – Bid and Construction Phase
29	Emergency Repairs to Griffiths Lake Dam - July 2006
30	Emergency Repairs to Griffiths Lake Dam – July 2006
31	Emergency Repairs to Griffiths Lake Dam – July 2006
32	Hearns Pond Repair
33	Hearns Pond Repair – January 2007
34	Hearns Pond Repair – January 2007