Washington Aqueduct
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The Washington Aqueduct is the public water supply system serving Washington, D.C. and parts of its suburbs. One of the first major aqueduct projects in the United States, the Aqueduct was commissioned by Congress in 1852, and construction began in 1853 under the supervision of Montgomery C. Meigs and the US Army Corps of Engineers (which still owns and operates the system). The Aqueduct went online on January 3, 1859, and has been in continuous use ever since. It is listed as a National Historic Landmark, and the Cabin John Bridge is listed as a Historic Civil Engineering Landmark.
The centerpiece of the Aqueduct is a 12-mile (19 km) pipeline which connects the system's dam at Great Falls, Virginia with the Dalecarlia Reservoir on the border with Montgomery County, Maryland. The pipeline runs along what is now MacArthur Boulevard, traversing some of the higher cliffs along the Potomac River; one of the bridges in the system, in Cabin John, Maryland, was the longest masonry arch bridge in the world for 50 years after its completion. Water from Dalecarlia also flows on to the Georgetown Reservoir in Georgetown, and from there to the McMillan Reservoir through the Washington City Tunnel.
The system originally used a single pipe for water delivery, and did not have any water treatment plants, relying instead on the reservoirs to act as settling basins. By the turn of the 20th century, however, Washington's growth and the high amount of sediment in the Potomac's water kept the reservoirs from doing their jobs well, and so the first treatment plant, a massive slow sand filter bed system, was installed at McMillan Reservoir, and was completed in 1905. The McMillan plant was not replaced until 1985, when a rapid sand filter plant was opened adjacent to it; efforts are under way to redevelop the land the slow sand plant used, while maintaining some of the plant's sand silos for historical purposes.
In the 1920s, the Aqueduct was upgraded with the addition of a second pipe from Great Falls to Dalecarlia, and a rapid sand filter plant was built at Dalecarlia Reservoir which went online in 1927. The Dalecarlia plant is the biggest of the two plants in the system, having been upgraded in the 1950s, and is the plant that serves the Virginia communities that use the Aqueduct.
The Aqueduct is a wholesale water supplier; the communities it serves are responsible for billing customers and managing water mains.
[edit] Service area
- Washington, D.C. and most of the federal installations in the city (via DCWASA)
- Arlington County, Virginia
- The city of Falls Church, Virginia and part of Fairfax County (particularly McLean)
[edit] External links
- Official site
- A longer history of the system, from the C&O Canal site
- Pictures of the McMillan slow sand plant, with history
- ASCE History and Heritage of Civil Engineering: Cabin John Aqueduct
- National Historic Landmarks Program: Washington Aqueduct
- U.S Army Corps of Engineers – Historical Vignettes
