Edenville DamThe Edenville Dam is located on the Tittabawassee and Tobacco Rivers near Edenville, Michigan. The Edenville Dam was built to provide water level control for the purpose of hydro-electric power generation and received its original license from FERC in 1998. On May 19, 2020, an extreme rain event caused the Tittabawassee and Tobacco rivers to swell and resulted in the breach of the Edenville Dam. Source: Four Lakes Lake Level Study by Spicer Group |
Edenville Dam interim Repair Measures
Phase I Interim Stabilization Measures at Tobacco Spillway
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Phase II Interim Stabilization Measures at Edenville Spillway
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Quick Facts
$96.5 million |
2,875 |
2026 |
$115 - $460* |
Cost to Repair |
Waterfront Properties |
Estimated Lake Return Date |
Estimated Annual Capital Assessment Range |
*Capital Assessment estimates are subject to variation of +/- 30% because of cost sensitivities such as construction costs, the financing term and interest rates.
Edenville Dam will require demolition of damaged structures - the spillway and powerhouse - and construction of new primary and auxiliary spillways.
Edenville Dam will require demolition of damaged structures - the spillway and powerhouse - and construction of new primary and auxiliary spillways.
Long-Term Restoration
Critical items
Spillway Adequacy
- Edenville is classified a high hazard dam. Prior to May 2020 flood, the total spillway capacity (Edenville + Tobacco) was approximately 20,670 cubic feet per second (cfs) before water would begin overtopping embankments
- Prior State of Michigan 1/2 PMF was 25,000 cfs
- Based on current on-going studies and recent flood, this will increase
- Based on current on-going studies and recent flood, this will increase
- FLTF study currently estimating future spillway requirement being 52,275 cfs
- Spillway requirements still being finalized based on
- PMP and PMF studies
- Inflow Design Flood Study
- State of Michigan Dam Safety Task Force
- EGLE approval
- PMP and PMF studies
- The left embankment completely breached. Portions of the remaining embankments were damaged due to rapid reservoir drawdown and scour
- Remaining embankment slopes are steep and don’t meet stability criteria
- Embankments leak excessively. No seepage cutoff and no internal filter zones to protect against seepage-induced internal erosion
- Total spillway capacity is significantly lacking
- Geotechnical investigations and structural analyses are required to support design of new embankments and repair of existing embankments
- All water retaining structures will need to be thoroughly evaluated and designed to meet State and federal dam safety standards
Risk-based design approach
- The IDF/risk-based approach aligns with FEMA guidelines and recommendations of the Michigan Dam Safety Task Force guidelines for Michigan dams
- Inflow Design Flood that requires these steps:
- Site-specific Regional Probable Maximum Precipitation (PMP) studies which are underway.
- Perform downstream Inundation mapping assuming dam failure for a range of flows starting from the 100-year flood up to the PMF
- Determine the incremental hazard increase and consequences of failure for a range of flood flows up to the PMF
- Use risk-based, IDF approach to inform the design spillway capacity – no less than 200-year but possibly less than the ½ PMF
Resources
Contacts
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