No rock-problem was encountered in dredging the canal. The cost was
below what the engineers estimated it would be--less than thirty cents
a cubic yard. But a novel situation did develop; a condition that would
have sent the cost sky-rocketing if an Orleanian had not met the
difficulty.
Louisiana is what geologists call a region of subsidence. The gulf of
Mexico formerly reached to where Cairo, Ill., now is. Washings from the
land, during the slow-moving centuries, pushed the shoreline ever
outward; the humus of decaying vegetation raised the ground surface
still higher. This section of Louisiana, built by the silt of the
Mississippi, was of course the most recent formation.
Twenty thousand years ago, say the geologists, there were great forests
where Louisiana now is. Among these mighty trees roamed the glyptodont;
the 16-foot armadillo with a tail like the morning-star of the old
crusaders, monstrously magnified; the giraffe camel; the titanothere;
the Columbian elephant, about the size of a trolley car and with
15-foot tusks; the giant sloth which could look into a second-story
window; here the saber-toothed tiger fought with the megatherium;
mighty rhinoceroses sloshed their clumsy way, and huge and grotesque
birds filled the air with their flappings.
As the subsoil packed more solidly, this wilderness in time sunk
beneath the waters. The Mississippi built up its sandbars again, storms
shaped them above the waves, marsh grass raised the surface with its
humus, and another forest grew. This, in turn, sunk. And so the process
was repeated, time after time.
At different depths below the surface of the ground the remains of
these forests are found today, the wood perfectly preserved by the
dampness. And through this tangled mass the dredges had to fight their
way.
It was a task too great for the ordinary type of 20 or 22-inch suction
dredge, even with the strength of 1,000 horses behind it. When they met
these giant stumps and trunks they just stopped.
A. B. Wood, of the sewerage and water department, had already designed
and patented a centrifugal pump impeller adapted to the handling of
sewerage containing trash. Learning of this, W. J. White,
superintendent of dredging on the Canal, asked him to design a special
impeller, along similar lines, for the dredge Texas.
Results from the invention were remarkable. During the thirty days
immediately preceding the installation the dredge had suffered delays
from clogged suction which totalled 130-3/4 hours. During the thirty
days immediately succeeding installation the total of delays for the
same reason was cut down to 71-1/2 hours. The average yardage was, for
the earlier period, 152 an hour, of actual excavation; and for the
later period, 445 an hour--an increase of almost 200 per cent. The
situation had been met.
This was the period when the cost of labor and material began to jump.
Employers were bidding against each other for men, and the government's
work practically fixed the price of supplies.
George M. Wells, consulting engineer, in his report of December 9,
1918, to the Dock Board, summarized labor increases over the scale when
the work was begun, as follows: Unskilled labor, 54%; pile driver men,
40%; machinists, 40%; blacksmiths, 40%; foremen and monthly, 15 to
40%--an average increase of 40%. Materials had advanced, he went on to
show, as follows: Gravel, 72%; sand, 25%; cement, 10%; lumber (form),
70%; timber, 40%; piles, untreated, 40%; piles, treated, 25%. These
increases, together with the expansion of the plans requiring a canal
of maximum depth, instead of the pilot cut of fifteen feet, as
originally planned; the insistence of the Levee Board that levees in
the back areas must be raised to elevation 30; development of
unforeseen and unforeseeable quicksand conditions in the various
excavations; requirements of railroads for bridges of greater capacity
and strength than needed; building of a power line to the Foundation
Company's plant--not a Dock Board job, but one that the conditions
required it should finance then; and other expenses, besides delaying
the work, made another bond issue necessary to finish the job.
At its meeting of February 26, 1919, President Thompson laid the matter
before the board. It decided to issue $6,000,000 of bonds, for which
the same syndicate of bankers that had taken the other two offered 96.
Liberty bonds were then selling at a big discount, and this seemed the
best terms on which the money could be secured.
This gave a total issue of $12,000,000 to date, the interest on which
amounted to $600,000 a year. The Levee Board raised its share of the
"rental" to $550,000, to guarantee the interest; the Public Belt
Railroad's $50,000 made the total complete.
In the meantime ships were beginning to bulk large on the ways of the
Foundation and the Doullut & Williams yards. The Foundation company
launched its first, the Gauchy--a 4,200-ton non-sinkable steel ship,
built for the French government--in September, 1919; and the Doullut &
Williams company launched its first, the New Orleans, a steel vessel of
9,600 tons, the largest turned out south of Newport News, built for the
Shipping Board, in January, 1920. These were followed by four sister
vessels from the Foundation yard and seven from the Doullut & Williams
plant. The former went to sea through Bayou Bienvenu and the latter
through Lake Pontchartrain. The Doullut & Williams yard is a large one.
Originally planning a mere assembling yard, the Foundation Company had
subsequently developed the greatest steel fabricating plant in the
South--so confident it was that New Orleans would carry through the
project.
And, too, the New Orleans Army Supply Base that Uncle Sam was building
on the river end of the Industrial Canal was rapidly rising--the
facility that was to double the port storage capacity of New Orleans
when it was finally completed in June, 1919.
The canal is 5-1/3 miles long. Between river and lock the canal prism
will be 125 feet wide at the bottom and 275 feet at the top; between
the lock and the lake, 150 feet wide at the bottom and 300 feet wide at
the top. It is an excavation job of 10,000,000 cubic yards. Five
hundred thousand flat cars would be required to carry that dirt--a
train more than 4,000 miles long.
By September, 1919, the canal had been entirely dredged, except for the
2,000-foot channel between the lock and river, which must be left until
the last, to a width of about 150 feet and a depth of 26 feet. Since
then, the labor has been concentrated upon the lock. But twenty-six
feet will float a vessel carrying 6,000 bales of cotton. Full
dimensions, however, will be developed, and the Canal, with a system of
laterals and basins such as are found in Europe, will be an Inner
Harbor capable of indefinite expansion.