2014 nwha conference doug johnson, p.e. portland regional engineer

2014 NWHA CONFERENCE

Doug Johnson, P.E.

Portland Regional Engineer

Framework for dam safety in the NW from FERC’s perspective: what were the gamechangers and where are we headed?

Game Changers

• St. Francis• Lower San Fernando• Teton• Taum Sauk• Ka Loko• Varick

St. Francis (1928)

Why a Game Changer?

• Driver for Establishing the California Division of Safety of Dams

• CA DSOD became a model for many other state dam safety programs.

Lessons Learned

• Importance of a complete understanding of abutment and foundation stability.

• Hubris is not good for dam safety!

Lower San Fernando (1971)

Why a Game Changer?

• Brought the issue of liquefaction of embankment dams to the forefront

• Nearly the worst dam disaster in the U.S.• 65,000 people evacuated

Dam and Valley Housing

Lessons Learned

• Susceptibility of hydraulic fill dams to seismic loadings

• Greater understanding of liquefaction of dams• Board’s of Consultants don’t 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.

Teton (1976)

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)

Taum Sauk (2005)

Why a Game Changer?

• Brought concerns with owner’s 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)

Ka Loko (2006)

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• Don’t mess with things you don’t understand;

get expert help• Independent inspections matter

Varick (2010)

Federal Energy Regulatory Commission

Lock 7

PowerhouseForebay

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 won’t have to relive these tragedies.