Settled by the French in 1718 on Â“highÂ” ground between the Mississippi River and Lake Pontchartrain, New Orleans has battled flooding throughout its history. In the 19th century, a moderate rainfall was enough to flood parts of the city, often for as long as a week, according to the Sewerage and Water Board of New Orleans (SWBNO). As late as 1885, photos show 2 to 3 feet of water covering streets in the main business district. Additionally, lack of sanitary sewer and potable water supply systems caused deadly outbreaks of typhoid fever, yellow fever, and cholera. In 1893, planning began on three, vital municipal systems: drainage, water supply, and sanitary sewers. To attack the drainage problem, the New Orleans City Council appointed three men as an Advisory Board of Engineers - Rudolph Hering, a renowned hydraulic and sanitary engineer from New York; Henry B. Richardson, chief state engineer of Louisiana; and Maj. Benjamin M. Harrod, former chief engineer for the city of New Orleans.
The board completed topographic and hydrographic surveys of the city, but design of the drainage system fell to City Engineer L.W. Brown. His original plan, according to a U.S. Army Corps of Engineers (Corps) report, included 95 miles of drainage canals (30 miles lined and covered) and eight pumping stations with a total capacity of 18,991 cubic feet per second - more than 8 million gallons per minute.
The New Orleans Drainage Commission, formed in 1896 and later merged with the SWBNO, began implementing Brown's master drainage plan. Harrod was appointed chief engineer. Construction began in 1897 with three initial contracts awarded to the National Contracting Co. of New York - the central electric power station and three of the pumping stations; the lined and covered canals; and the open canals.
Photo from 1930 of pumping station number 1 touts the size and capacity of New Orleans drainage system at that time.
Brown's drainage scheme never was constructed completely as designed. Three pump station locations were changed, two stations were dropped from initial construction, and the alignment and locations of several canals were altered, according to the Corps' report. By 1905, the drainage system comprised almost 40 miles of canals and six pumping stations with a capacity of 5,000 cubic feet per second. The partially completed system had immediate impacts, significantly decreasing mortality rates and opening up previously wet land for development. But by 1910, that development, which included numerous buildings and paved areas that increased runoff and deceased infiltration, created a need for a new plan.
Harrod and Hering recommended improvements in the major canals and an increase in pumping capacity. New and larger, 12-foot screw pumps, designed by Albert Wood, a mechanical engineer for the city, helped increase the drainage system's capacity to 13,000 cubic feet per second by the mid-1920s. Wood later designed a 14-foot screw pump.
New Orleans continued to expand and improve its drainage system, undertaking major projects in the 1940s, 1950s, and periodically to the present day. For example, new pump stations and improved canals are part of a $140 million, joint Corps and SWBNO program authorized in 1996. Currently, the drainage network includes about 90 miles of open canals and 90 miles of subsurface canals. Twenty-two pumping stations provide a total capacity of more than 29 billion gallons per day, enough to empty in 24 hours a lake that is 13.5 feet deep and 10 square miles in area, according to the SWBNO.
Most of the water is pumped into Lake Pontchartrain (its levees are lower than the Mississippi River levees); however, four stations pump water into the Intracoastal Waterway or the Industrial Canal. Additionally, 13 highway underpass stations, each with two or three pumps, operate automatically if the water rises. For more information on the system, visit www.swbno.org.