And the work went on, with every effort concentrated on economical construction.
SIPHON AND BRIDGES.
As an incident in the work of building the Industrial Canal, it was necessary to create a disappearing river.
This is the famous siphon—the quadruple passage of concrete that will carry the city's drainage underneath the shipway. It is one of the largest structures of its kind in the country.
A word about New Orleans' drainage problem. The city is the bowl of a dish, of which the levees against river and lake are the rim. There is no natural drainage. The rainfall is nearly five feet a year, concentrated at times, upon the thousand miles of streets, into cloudbursts of four inches an hour and ten inches in a day. In the boyhood of men now in their early thirties it was a regular thing for the city to be flooded after a heavy rain.
To meet the situation, New Orleans has constructed the greatest drainage system in the world. There are six pumping stations on the east side of the river, connected with each other by canals, and with a discharge capacity of more than 10,000 cubic feet a second. The seven billion gallons of water that these pumps can move a day would fill a lake one mile square and thirty-five feet deep.
Three of the canals empty into Lake Pontchartrain, the fourth, the Florida Walk Canal, into Bayou Bienvenu, which leads into Lake Borgne, an arm of Pontchartrain.
Because of this drainage contamination, the lake shore front of New Orleans has been held back in its development. Yet it is an ideal site for a suburb—on a beautiful body of water, and just half a dozen miles from the business district.
So the Sewerage and Water Board has been planning ultimately to turn the city's entire drainage into Bayou Bienvenu, a stream with swamps on both sides, running into a lake surrounded by marsh.