Pacoima Dam

Pacoima Dam
The Pacoima Dam, viewed from Contract Point.
CountryUnited States
LocationLos Angeles County, California
Coordinates34°20′05″N 118°23′47″W / 34.33472°N 118.39639°W / 34.33472; -118.39639
StatusIn use
Construction began1925; 99 years ago (1925)
Opening date1928; 96 years ago (1928)
Owner(s)Los Angeles County Department of Public Works
Dam and spillways
Type of damarch
ImpoundsPacoima Creek
Height371 feet (113 m)
Length640 feet (200 m)
Spillways1
Spillway typeService, concrete tunnel
Spillway capacity24,700 cubic feet per second (700 m3/s)
Reservoir
CreatesPacoima Reservoir
Total capacity3,777 acre⋅ft (4,659,000 m3)
Catchment area27.8 square miles (72 km2)
Surface area68 acres (28 ha)

Pacoima Dam is a concrete arch dam on Pacoima Creek in the San Gabriel Mountains, in Los Angeles County, California. The reservoir it creates, Pacoima Reservoir, has a capacity of 3,777 acre⋅ft (4,659,000 m3)[1]

Built by the Los Angeles County Flood Control District, which became part of the Department of Public Works, it was completed in 1928. At the time, the 371 foot (113m) high dam was the tallest arch dam in the U.S.[1]

The dam is situated approximately 1 mile (1.6 km) northeast of Sylmar, above the San Fernando Valley.[1] As a flood control structure, district routinely compensates for hydraulic deficiencies in downstream areas by restraining flows of stormwater released from the dam.[2]

Instrumentation

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As construction of Pacoima Dam began, the County of Los Angeles hired Roy W. Carlson[3] as their concrete and soil testing engineer. He developed the world's first strain meter which could be embedded in concrete. He also developed an adiabatic calorimeter and electrical-resistance thermometers to find why the temperature of concrete increased during curing and how best to avoid cracking caused by these stresses.[4]

Earthquake monitoring

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The Pacoima Dam withstood, but was damaged by the very strong (>1 g) ground movement which occurred during both the 1971 San Fernando and 1994 Northridge earthquakes. Because of concerns about the stability of the dam and especially its response to potential future earthquakes, the County of Los Angeles, with the technical support of the USGS, began monitoring the dam using continuous GPS.[1]

See also

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References

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  1. ^ a b c d Hudnut, Kenneth W. & Behr, Jeffrey A. (1998). "Continuous GPS monitoring of Structural Deformation at Pacoima Dam, California". Seismological Society of America. Retrieved January 23, 2014.
  2. ^ Sahagún, Louis (March 18, 2023). "Flooding vulnerabilities of L.A. River's Glendale Narrows spark concern amid record rain". Los Angeles Times. Retrieved March 18, 2023.
  3. ^ Electrical Engineering and Computer Sciences, UC Berkeley "Dr. Roy W. Carlson"
  4. ^ Rogers, J. David (2012). "DAMS AND DISASTERS: a brief overview of dam building triumphs and tragedies in California's past" (PDF). University of California Davis. Retrieved January 23, 2014.
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