A great force of men began to throw up by hand, the levees that were to serve as banks for the turning basin, the lock and other portions of the canal. This levee would keep the liquid material, dredged out, from running back into the excavation. The turning basin, 950 feet by 1,150 feet, was an expansion of the original industrial basin. Situated several hundred feet from the lock, its purpose is to enable ships entering the canal from the river, and passing through the lock, to turn in, as well as to furnish a site for the concentration of industries. The Foundation Company had in the meantime decided to establish a shipyard on this basin; its engineers were on the ground, and its material was rolling. One dredge was sent around Lake Pontchartrain to commence boring in from that end. This could not be done on the river end. The Mississippi is too mighty a giant to risk such liberties. The 2,000-foot cut between the river and the lock would have to be done last of all, when the rest of the canal and the lock were finished, and the new levees that would protect the city against its overflow, were solidly set. But a few hundred feet from the turning basin, was Bayou Bienvenu, which runs into Lake Borgne, part of Lake Pontchartrain, and one of the refuges of Lafitte in the brave days when smuggling was more a sport of the plain people than it is now with European travel restricted to the wealthy. So through Bayou Bienvenu a small excavator was sent to cut a passage into the turning basin, to allow the mighty 22-inch dredges to get in and work outwards towards the lake and the lock site. The problem was further complicated by the Florida Walk drainage system, which emptied into Bayou Bienvenu, and by the railway lines that crossed the site of the Canal. These railways were the Southern Railway, at the lake end, the Louisville & Nashville, at the middle, and the Southern and Public Belt near the turning basin on Florida Walk. For them, the Dock Board had to build "run-around" tracks, to be used while their lines were cut to enable the dredging to be made and the bridges to be constructed. For the drainage, the plans called for the construction of an inverted siphon passing under the Canal, a river under a river, so to speak. In the meantime, however, the drainage canal had to be blocked off with two cofferdams, to cut off the water from the city and the bayou, and enable the construction of the siphon between. Additional railroad tracks, too, had to be built to handle the immense volume of material needed for the work; roads had to be built for getting supplies on the job by truck; the trolley line had to be extended for the transportation of labor.