California Dept. of Water Resources investigators are trying to discover why a steel bulkhead failed on July 22 during routine hydraulic tests at Oroville Dam. Five workers were injured when a 6-ft-tall, 10-ft-wide nonstructural steel wall in a diversion tunnel at the dam’s powerplant collapsed during a routine annual hydraulic-valves test. The incident shut the plant for about two hours until the bulkhead was repaired, according to Carl Torgerson, DWR chief of operations and maintenance. The investigation will take about two months to conclude, says Pete Scheele, DWR field division chief. Officials from the state Occupational Safety and Health Administration
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.