Was it a close call at Upper San Fernando 6-028 Dam? It certainly was. We are standing before a testament to both human ingenuity and the raw power of nature.
Upper San Fernando 6-028 Dam is located in Los Angeles County. It stands as a reminder of the San Fernando earthquake.
The Van Norman Dams, which include Upper San Fernando 6-028 Dam, once supplied Los Angeles with about 80 percent of its water. The dams formed the terminus of the Los Angeles Aqueduct. The construction of the Upper Van Norman Dam started with 42 feet of hydraulic fill. Then in 1922 the dam was raised 18 feet using rolled fill.
The 1971 San Fernando earthquake inflicted significant damage on Upper San Fernando 6-028 Dam. The Upper Van Norman reservoir was operating at about one-third capacity when the earthquake struck. The quake lowered the dam height by 3 feet. It also displaced the dam laterally by 5 feet.
The earthquake’s impact led to major changes in how public agencies view seismic safety. Engineers reassessed dam safety. The near failure of the Lower Van Norman Dam highlighted the risks associated with embankments made of fine sands and silts. Numeric dynamic analysis of dams became crucial.
In the aftermath, reconstruction of Upper San Fernando 6-028 Dam was considered. Geologic evaluation revealed inherent instability in the dam’s foundations. Instead the Los Angeles Dam was constructed between the original Lower and Upper Van Norman Dam structures. It was built in a more stable location.
During the 1994 Northridge earthquake the Lower Van Norman reservoir area was again severely damaged. It was then in use only as a holding basin. The consequences were minor.
The story of Upper San Fernando 6-028 Dam is a crucial lesson in engineering. It is a lesson about the awesome power of earthquakes. It also underscores the importance of continuous vigilance in maintaining our infrastructure. Upper San Fernando 6-028 Dam stands as a silent sentinel. It is a guardian of both water and memory.