Sheffield Dam, Liquefaction Failure, from 1925 Santa Barbara Earthquake
Johnstown, PA Flood – South Fork Dam Failure
31 May 1889 – 2,209 Fatalities
Source: Virtual Tour
The Los Frailes tailings dam (Aznalcóllar, Spain) was a tailings storage dam. The failure type has been categorized as a foundation sliding failure (or loss of bearing, which then initiated sliding). The weakest part of the foundation was comprised of blue marl (clay and approximately 25% carbonate – CaCO3).
What are some iconic types of Heavy Equipment in the industry?
D10 Dozer – Operating Weight: 154,700 lbs (Caterpillar)
772 Off Highway Truck (Caterpillar)
Gross Operating Weight: 181,000 lbs, Payload: 50 tons, Heaped: 41 cu. yd.
992 Wheel Loader – Bucket Capacity: 14 to 16 cu. yd. (Caterpillar)
For Concrete Structures: OBE (operational basis earthquake) = 144-yr Return Period (50 percent chance of being exceeded in 100 years).
Max. Design EQ: for Structures Defined As Critical use MCE, In general for other structures, MDE = 950-yr return period (10 percent chance of being exceeded in 100 years).
MCE is defined as the greatest earthquake that can reasonable be expected to be generated by a specific source (which comes from a deterministic site hazard analysis).
USACE references: Stability Analysis of Concrete Structures, Earthquake Design and Evaluation of Concrete Hydraulic Structures, Earthquake Design and Evaluation for CW Projects. Safety of Dams – Policies and Procedures.
Dams that fall under State jurisdiction are subject to: Statutes and Regulations Pertaining to Supervision of Dams and Reservoirsby the California Division of Safety of Dams (DSOD). Dam height (in feet) is measured from the downstream toe to the maximum storage elevation/spillway. Storage capacity is in the units of acre-feet.
1 foot (ft) = 0.3048 meters (m), 1 acre-foot (ac-ft) = 1233.5 cubic meters (m^3)
St Francis Dam Failure, 12 March 1928. Failed catastrophically upon its first full filling, near midnight, killing at least 450 people. Seepage (dirty water) was observed the day of the failure. A massive landslide occurred in the dams left abutment, comprised of schist.
“Greatest American civil engineering failure in the 20th century.”
Historical Society of Southern California: St. Francis Dam Disaster.
Excellent Photo Display at: St. Francis Dam collapse – Framework – Photos and Video – Visual Storytelling from the Los Angeles Times.
Type: Concrete Gravity Thick Arch Dam, Maximum Height = 195 feet, Storage (at time of failure) = 38,000 acre-feet
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LOWER SAN FERNANDO DAM FAILURE, 9 FEBRUARY 1971, LOS ANGELES, CA. Due to Liquefaction and the Magnitude 6.7 San Fernando Earthquake of 1971.
Construction began in 2011. A zoned earth and rock fill dam that is 220 feet high.
Two ancient landslides were discovered during excavation in 2012, but was not found in pre-construction geotechnical investigations. An additional 3.5 million cu yds of excavation was required to remove the landslide materials.
Still in Planning Stages, what is called a “prior consultation,”…”to discuss and evaluate benefits and associated risks of the project which may have significant impacts on the environment and people.”