Lessons Learned Susceptibility of hydraulic fill dams to seismic loadings Greater understanding of liquefaction of dams Boards of Consultants dont always get it right (There had been a BOC in response to DSOD concerns. The BOC had concluded the dam was OK. Only the facts that that the EQ was in February and the water that would fill the reservoir was locked in snow in the Sierra and one outlet tower withstood the shaking prevented a disaster.
Why a Game Changer? One of the Key Elements in the Creation of FEMA by Presidential Directive Driver for passage of Federal Dam Safety Act Affected federal and state dam safety programs throughout the U.S. 11 people died
Lessons Learned Hubris is (again) a bad thing Piping of fill dams is a critical failure mode Proper treatment of abutments and foundations is critical (a lesson that should have been learned at St. Francis)
Why a Game Changer? Brought concerns with owners dam safety program to the forefront Highlighted risks associated with remote operation Systems Failure
Lessons Learned Spillways are a good thing Remote operation has risks as well as benefits Assumptions regarding how a dam was built should be verified (dam was supposed to be dumped rockfill however in the breach area the material was more like a loosely compacted soil)
Why a Game Changer? Owner plead no contest to first-degree reckless endangerment, a felony, for his role in the 2006 Ka Loko dam failure. Seven people died.
Lessons Learned Spillways are a good thing (see Taum Sauk) The owner had filled in the spillway. Low Hazard dams may not be Dont mess with things you dont understand; get expert help Independent inspections matter
Federal Energy Regulatory Commission Lock 7 Powerhouse Forebay Spillway and Bypass Reach
Background: During the fall, large schools of trophy Chinook salmon begin staging at the river mouth and make their way to the impassible Varick dam
Incident: Approximately 12:44 pm on September 28, 2010: – Four fishermen were swept downstream – By activating three generating units at High Dam and only one unit at Varick water spilled over the dam and water levels increased in the bypass reach of the Varick Development causing the fishermen to be caught off guard and swept off of their feet into the deep water in the tailrace channel. – Their location prior to being swept away was standing in the river in an area along the diversion wall between the bypass reach and tailrace channel
Why a Game Changer? Understanding that operations can lead to public safety incidents up to and including fatalities
Lessons Learned Not knowing the potential consequences from operating a powerhouse may result in fatalities. Identified lack of adequate maintenance, training, and surveillance which could have been easily avoided or remedied Public safety plans are a critical part of any ODSP and operating procedures. Projects with remote operation and no eyes (i.e. cameras or staff) have added risks, especially if there is public recreation usage at the facility
Where Are We Headed? Hopefully we learn more lessons than we forget. (see St. Francis/Teton and Taum Sauk/Ka Loko) We need to work together to understand the safety incidents the dam safety community, and other industries, have suffered so that we wont have to relive these tragedies.