The Los Angeles Aqueduct was started in 1908 and finished in 1913 at a cost of about $23 million. It diverts eastern Sierra mountain streams from the Owens Valley to reservoirs in the Los Angeles area. When it was completed, the Los Angeles Aqueduct was the largest single water project in the world.
The elevation at the aqueduct intake is about 3800 feet and the elevation at the Upper Van Norman Reservoir (now Lake) is about 1200 feet. Thus, the water would almost always be flowing downhill allowing gravity to power its entire 233 mile length. However, in order to flow through valleys, it would have to travel uphill. To accomplish this, the water was contained in steel pipes above ground or concrete pipes below ground. The pressure developed in the down slope forces (siphons) the water through the up slope. The aqueduct is underground in Whitney and Elsmere Canyons.
In Elsmere Canyon, construction took place in 1911 and 1912. The section of the aqueduct through Whitney and Elsmere Canyons is noteworthy for its use of concrete in the siphon rather than the more usual riveted steel construction. The Elsmere siphon connects Tunnel 103 (from Whitney Canyon) to Tunnel 104, which empties out at the “cascades” in the northern San Fernando Valley. Tunnel 104 was actually completed in 1910.
From the Sixth Annual Report of the Bureau of the Los Angeles Aqueduct (July 1911):
“The Elsmere Siphon of reinforced concrete, connecting Tunnels 103 and 104, has been completed. It is 548 feet long, 10 feet in diameter, and will operate under a maximum head of 45 feet. This siphon has not yet been filled with water, as it is desirable to give the concrete two months to age before putting it to the test.
Tunnel 104, which is 9,172 feet in length, passing through the crest of the Santa Susanna Mountains near Newhall and through the Newhall oil field, was considered a very difficult piece of work, many adverse conditions such as water, gas, oil and swelling ground being encountered, but despite these obstacles, the work was completed within the estimated cost, and during the progress of the excavation, there was not a single accident that necessitated the removal of the victim to the hospital.
The Whitney Siphon is a reinforced concrete pipe 10 feet in diameter, with an 8-in shell on the top and sides, and rests on a broad concrete base. The pipe was cast in position. The reinforcing steel consists of half-inch circular iron rods so spaced as to give a factor of safety of four on the steel. It is probable, however, that the concrete alone has sufficient strength to resist the bursting pressure, as the mixture was made very rich to obtain both watertightness and strength. Two expansion joints were put in this pipe. They are of the “Z” type and coated with asphalt paint. The only apparent leakage that has occurred at any place in the pipe is at one of these joints. In the Elsmere Siphon, which was built subsequently, no expansion joints were used. As far as known, in diameter these are the largest reinforced concrete pipes in the United States, but larger ones have been built in Spain.”
The historic pictures (which are NOT in the public domain and are used by permission) were taken by Joseph Barlow Lippincott, an assistant chief engineer for the project. The chief engineer was William Mulholland.
More aqueduct information can be found at the Story of the Los Angeles Aqueduct website and on my Whitney Canyon aqueduct webpage.
(via Los Angeles Aqueduct)