ENDS OF THE CANAL
While the completed Panama Canal does not wed the two oceans, or
permit their waters to mingle in Gatun Lake, it does bring them a
little closer together. On the Atlantic side a sea-level channel has
been dug from deep water due south to Gatun, a distance of 7 miles. On
the Pacific side a similar channel has been dug from deep water in a
northwesterly direction to Miraflores, a distance of 8 miles. It
follows that 15 of the 50 miles of the canal will be filled with salt
water. The remaining 35 miles will be filled with fresh water supplied
by the Chagres and the lesser rivers of Panama. The task of digging
these sea-level sections was a considerable one and almost every
method of ditch digging that human ingenuity has been able to devise
was employed. Steam shovels, dipper dredges, ladder dredges,
stationary suction dredges, and sea-going suction dredges, all
contributed their share toward bringing the waters of the Atlantic to
Gatun and those of the Pacific to Miraflores. In addition to these
methods, on the Pacific side use was made of the hydraulic process of
excavating soft material, washing it loose with powerful streams of
water and pumping it out with giant pumps.
[Illustration: THE DISASTROUS EFFECTS OF SLIDES IN CULEBRA CUT]
[Illustration: W. G. COMBER
U. S. LADDER DREDGE "COROZAL" AND ONE OF HER MUD BUCKETS]
As one travels along the Pacific end of the canal he is reminded of
the words of Isaiah:
"Every valley shall be exalted, and every mountain and hill shall
be made low; and the uneven shall be made level, and the rough
places a plain."
Hundreds of acres of low, marshy land have been filled up, either with
mud from the suction dredges and the hydraulic excavators, or with
spoil from Culebra Cut. Much of this made land will be valuable for
tropical agriculture, while other parts will never serve any purpose
other than to keep down the marshes. But they afforded a dumping
ground for material taken out of the canal prism, and added something
to the improvement of health and living conditions on the Isthmus.
Probably the most interesting process of excavation in the sea-level
channels was that of the sea-going suction dredges. These dredges took
out material more cheaply than any other kind of excavating machinery
used on the Isthmus. Two of them were put to work in 1908, about the
time the operations reached full-blast and have been kept in
commission ever since. While it cost as much as $70,000 a year to keep
each one in commission, they were able to maintain an annual average
of about 5,000,000 cubic yards of material excavated at a cost per
yard of 5 cents and even less. With steam shovels it ranged from 10 to
20 times as much per yard. These big dredges were built with great
bins in their holds and equipped with powerful 20-inch centrifugal
pumps. When at work they steamed up and down the channel, sucking up
the mud, and carrying it out to sea.
Another interesting dredge used was the big ladder dredge Corozal. It
is a great floating dock, as it were, with a huge endless chain
carrying 52 immense, 35-cubic-foot buckets. On the center line
amidships there is a large opening down to the water. The big elevator
framework carrying the endless chain goes down through this and into
the water at a considerable angle. The buckets pass around this, and
as they round the end of it their great steel lips dig down into the
material until filled, then they come up at the rate of three every
five seconds and deposit their burden in a huge hopper which conveys
it to the barge at the side of the dredge. The dredge is anchored fast
at a given place, and keeps on attacking the material beneath it until
the desired level is reached. This dredge, with the sea-going suction
dredges, will be retained as the permanent dredging fleet. The
stationary suction dredges at the two ends of the canal were used to
pump up the soft material and to force it out through long pipe lines
into the swamps or into the hydraulic cores of the earth dams.
[Illustration: THE _Corozal_ AND ITS METHOD OF ATTACK]
Several old French ladder dredges were rescued from the jungle and put
into commission at the beginning of the work, and they held out
faithfully to the end, dividing honors with the newer equipment in
hastening the day when the oceans might go inland to Gatun and
Miraflores. While they looked like toys beside such giant excavators
as the Corozal, they probably showed more efficiency than any other
class of excavators of their period of construction. They were
attended by large self-propelling scows built by the French. When
these were filled they steamed out to sea and dumped their burden and
then steamed back again for another load. Some of the dredges were
attended by ordinary barges which were towed out to sea by tugs and
dumped.
Another interesting machine used on the Pacific end of the canal was
the Lobnitz rock breaker. This consists of a sort of pile driver
mounted on a large barge. Instead of a pile driving weight there is a
big battering ram made of round steel, pointed at one end. It is
lifted up perhaps 10 feet and allowed to drop suddenly. As some of
these rams weigh as much as 25 tons their striking force may be
imagined. When the ram struck the rock the top would shake back and
forth like a bamboo pole, in spite of the fact that it was made of the
best steel and more than 15 inches in diameter. Sooner or later the
rams would break off at the water line, this being due to the fact
that the constant flexion at that point set the molecules in the steel
and took away all its elasticity.
It was found desirable to excavate a part of the sea-level channel
before the water was let into it. To accomplish this a big dam, or
dike, was built across the channel several miles inland, and steam
shovels were used behind this dike. As the work neared completion,
however, it was found advisable to let the water come further inland,
so that the dredges could extend the field of their activities. To do
this another dike was thrown across the channel about a mile north of
the first one, and water was admitted to the section of the big ditch
between these two dikes. The engineers were afraid to cut a small
ditch in the top of the first dike, and allow the water to eat the dam
away as it flowed in, for fear that it would rush in so rapidly it
would destroy the second dike. Therefore they filled the basin between
the two dikes by siphon and by pumping, a process which required the
drawing in of billions of gallons of water. This was accomplished in
due time, however, and then 16 tons of dynamite was placed in the no
longer useful dike. An electric spark did the rest.
The distinguishing features of the ends of the canal are the big
breakwaters at Toro Point, at the Atlantic end, and Naos Island, at
the Pacific end. The former extends from the shore out into the sea
for a distance of 2 miles and has a large lighthouse at the seaward
end. It was built by dumping stone from the shore out into the sea,
this process being followed by driving piles into the dumped stone and
building a railroad on the crest, over which the stone was hauled for
its further extension. The top of the breakwater is covered with huge
stones weighing from 8 to 20 tons each, these to make sure that it
will stand against the pounding of the waves. Two minor breakwaters
were also built at the Atlantic end to protect the terminal basin.
The big dike at Naos Island in the Pacific is more than 17,000 feet
long and transforms the island into the cape of a small peninsula.
There was a threefold purpose in its construction--to cut out the
cross currents that brought thousands of yards of sand and silt into
the canal channel, to afford a dumping place for a large quantity of
the spoil from Culebra Cut, and to make a connection with the mainland
for the fortifications on Naos, Flamenco, and Perico Islands. In
building it the engineers were under the necessity of first building a
trestle on which the spoil trains could be backed and dumped. The
piles had to be driven in soft, blue mud, and as the rock was dumped,
it sank down and down until, at places, ten times as much stone was
required as would have been necessary if the ocean bottom had been
firm. In addition to this thousands of trainloads of material were
dumped in the landward end of the dike, some 20,000,000 cubic yards of
material being thus disposed of.
The last part of the canal work to be completed will be the terminal
facilities at the ends of the big waterway. At the time this book went
to press they were something more than a year from completion, but the
indications were that they would be finished within the time limit
originally set for the completion of the canal itself. These terminal
facilities consist of dry docks, wharfage space, storehouses, and
everything else necessary to perform any service that might ordinarily
be required for passing ships, whether they be those of commerce or of
war. The main coaling station is to be established at the Atlantic
end. The storehouses, the laundry, the bakery, and the other equipment
of the Isthmian Canal Commission and the Panama Railroad also will be
made a part of the permanent terminal plant on that side of the
Isthmus.
A large dry dock is being built at the Pacific end having the same
usable dimensions as the canal locks, capable of accommodating any
vessel that can pass through the canal. The principal machine shops
will also be erected there, and a coaling plant of half the capacity
of the one at the Atlantic end will be provided. A little to the east
of the Pacific terminal works will be stationed the capital of the
Canal Zone, where the administrative offices, the governor's
residence, and two new towns will be built. The administration
building, which is to be a three-story structure of concrete, hollow
tile, and structural steel, is to occupy an eminence on the side of
Ancon Hill, which will afford a splendid view of the Pacific
fortifications, the entrance to the canal channel, a part of the port
works, and of the canal itself from the great continental divide to
the Pacific.
There one may sit and see ships coming into the canal, tying up at the
docks, sailing up the big ditch, and passing through the locks at
Miraflores and Pedro Miguel. Near by will be the permanent home of the
marines who will be stationed on the Isthmus, their barracks and
grounds occupying the broad plateau on the side of Ancon Hill made by
taking out the millions of cubic yards of stone required for the
concrete works on the Pacific side of the Isthmus. Two permanent towns
will be built at Balboa, one for the Americans and the other for the
common laborers. The American town will be built under the capitol
hill on a broad plain that was made by pumping hydraulic material into
a swamp and by dumping spoil from Culebra Cut.
When the terminal plant at Balboa is completed it will represent
probably the most extensive and adequate port works in the New World.
In addition to the main dry dock it will have a second one which will
be smaller, but which will be large enough to accommodate a majority
of the ships that will pass through the canal. The existing dry dock
at the Atlantic end will be continued in service.
It is certain that none of these port works will ever fail by reason
of insecure foundations. Wherever unusual loads were to be carried
great piers of reinforced concrete were sent down to solid rock, often
a distance of 60 feet below the surface. They consisted of a hollow
shell of reinforced concrete which was allowed to sink to hardpan of
its own accord or under heavy weight. These shells were built in
sections 6 feet high. The bottom section was 10 feet in diameter, and
the lower end was equipped with a sharp steel shoe. As the section cut
down into the earth of its own weight and that above it, laborers on
the inside removed the material under the shoe and as they did so it
sank further down. The sections above were only 8 feet in diameter,
and did not quite fill up the hole made by the bottom of the section,
thus overcoming all skin friction, and permitting the full weight of
the series of sections to fall on the lower one. A jet of water was
forced around the sinking pier all the time it was going down, and
this made its progress the more easy. At times the weight of the
superimposed sections was sufficient to force the pier down through
the soft mud, while at other times the material became so heavy that
even a 25-ton weight on top of the pier scarcely moved it. At one
place a stratum of material was struck about 25 feet below the surface
which yielded sulphuretted hydrogen gas. This affected the laborers'
eyes, and some of them had to go to the hospital for treatment. The
work of digging out the material was continued until the lower section
reached bed rock, where it was anchored. The sections themselves were
tied together with heavy iron rods. After they were firmly in place
the interior was filled up with concrete, itself reinforced, so that
the foundations became, in reality, a series of huge concrete piles, 8
feet in diameter, anchored to bed rock.
The coaling plants at the two terminals will be the crowning features
of the terminal facilities. With an immense storage capacity, and with
every possible facility for the rapid handling of coal, both in
shipping and unshipping it, no other canal in the world will be so
well equipped. The coal storage basin at the Atlantic end will hold
nearly 300,000 tons. This basin will be built of reinforced concrete,
and will permit the flooding of the coal pile so that one-half of it
will be stored under water for war purposes. It is said that
deterioration in coal is not as great in subaqueous storage, and at
the same time the pile is less subject to fire. The plant will be able
to discharge a thousand tons of coal an hour and to load 2,000 tons an
hour. Ships will not go alongside the wharves to be coaled, but will
lie out in the ship basin and be coaled from barges with reloader
outfits. Special efforts have been made to provide for the quick
loading of colliers in case of war. The coal handling plant at the
Pacific entrance will have a normal capacity of 135,000 tons and will
be able to handle half as much coal in a given time as the one at the
Atlantic end.
There will be big supply depots where ships can get any kind of stores
they need from a few buckets of white lead to an anchor or a hawser; a
laundry in which a ship's wash can be accepted at the hour it begins
its transit of the canal, for delivery by railroad at the other end
before it is ready to resume its ocean journey; an ice plant which
will replenish the cold storage compartments of ships lacking such
facilities. In short, it is proposed to attempt to do everything that
may be done to make more attractive the bid of the canal for its share
of business.