Los Angeles herald., 1907-12-24
JE77IES BUILT
IN NEW ORLEANS
GREAT HARBoR IMPROVEMENT
NEARLY COMPLETED
LARGE Sum of Money Expended by
Federal Government in Widen-
ing and Deepening
Waterway
BY Associated Press.

| BY Associated fresb.
! NEW ORLEANS, Dee. 2S.-One of the
greatest channel making undertakings ~
the history of American river improve
ments will be brought nearly to compile
| ton this week when the jetties at the
mouth of the southwest pass of the Ms
sissppi river are finished
| Those Jetties, after some dredging pe
| tween them is complete, will give ths
south one o the deepest harbors in the
world, by opening to the access of the
largest steamships afloat the 100 and 200
| foot depths of the lower Mississippi river
under the harbor thus made accessible,
and navigable water connection with at
least a dozen states bordering the Mis-
sissippi and Its tributaries, the Ohio, Mis-
souri,, Arkansas and Red rivers.
About $6,000,000 is being spent on this
Improvement by the United States gov
ernment which has the work in charge.
The new jetties were begun four years
ago. They are on a larger scale and
more substantial tlan the famous jetties
at the Mississippis south pass, an out
let which for over thirty years has been
the rivers commercial entrance. They
are nearly parallel walls, one about three
and the other four miles long. over a
half mile apart and built in the shoa'
water at the juncture OF the pass with
the Gulf of Mexico.
Their purpose is to confine and thus
accelerate the rivers current across a
mud bar about three miles broad, SO IA
to produce a channel at least 1000 feet
wide, with minimum depth of thirty
five feet. The swift current which they
have produced. aided by dredging, even
before their completion has caused tre-
mendous scour and has already made
fifty to eighty-f1ve feet of water in some
-t,..s TO- <f Il.
work the depth was but little over a
mans head.
To make the uniform contract depth
there is still in several spots about ten
feet of mud to be removed. 1t is ex-
pected that the high waters due within
few weeks will speed the remaining
mud deposits out to sea by the beginning
of next summer.
Walls Are Costly
Probably few walls ever have been con-
structed under greater difficulties than
were these Jetties. They are made of
willow, scantling stone and concrete,
and although in some places they are
not six fee. deen and although their
greatest depth is barely fifteen feet they
have cost 5. 100000. Every material en-
tering into their construction has been
brought from distances of 100 to 2"S
miles
The jetties have no foundation, but rely
for stability upon their broad basis. being
from 100 to so feet wide at the bottom
In contrast 10 this great width of basa
the concrete capping which forms the
top of the jetties and which is the work
receiving its finishing touches this week
is but few feet wide The Gaping Is
a sea wall four and one-half feet high.
and is the only portion of the jetties not
submerged.
The wall weighs between two and three
tons per lineal foot. The submerged
structure supporting this mass of con-
crete is made almos. entirely of willow
poles and brush
With the aid of framework of scant-
ling the willows were formed into So
called mattresses. broad, flat structures
resembling bed mattresses, in form each
about two feet thick, 200 feet long and
Carrying in width from thirty-five to 15J
feet. The mattresses were sunk one
above the other. with the widest at the
bottom and those above uniformly di
minishing in width as they approached
the surface.
The topmost mattresses were uniformly
thirty-five feet wide and at level with
the surface Of the water Heavy broken
stone was spread evenly over the ma
tresses to sink them. so that layer of
stone rests between each of these willow
structures. The greatest number OF
superimposed mattresses were five.
Part of the 10000 900 allotted to making
the channel is being spent in safeguards
several miles abcve the jetties to pre-
vent any increase in the flow of other
large outlets from the main river to the
gulf. This is being accomplished by
placing stone GOV red mattress sills on
the river bottom across the entrances
to these outlets. Several small bayous
leading from southwest pass to the gulf
will be entirely closed.