Savannah morning news. [volume] (Savannah) 1868-1887, 1882-03-03
OUR RIVER AND HARBOR.
GEN. Q. A. GILLMORE's REPORT.
How n Deeper aud Wider Channel
May be ObtaIned-PIanG. EstI-
mates, Recommendations and
COncIusfOn-An Exhaustive Re
view of the Navigation Problem.


to Congress the report Of Gen. Q. A. Gill
more, made upon a survey in compliance
with the requirements of the last river and
harbor bill, for the further improvements
necessary in the Savannah river and harbor,
and to Increase the depth of water to TWEEN
ty-two feet from the bar up to the city, and
also for widening the channel Of the SSvan-
nah river opposite the city to six hundred
feet Of uniform depth with the balance Of
the channel. The report Is as follows:
GENERAL-Sectiou of the river and harbor
act approved March 3, 1881, provides that an
examination or survey. or both, with estimates
of cost Of improvements proper, should be
made in the Savannah river and harbOr to In
crease the depth Of the water in said river and
harbor from the bar up to the city to % feet
and to make an estimate Of the cost OF widen
ing the channel of the Savannah river, oppo-
site the city, to 600 feet. Of uniform depth with
the balance Of the channel.
This work was assigned to my charge by de
partInent letter dated March 21, 1881, and
have the honor to submit the following report
thereon:
Such examinations as were considered to be
sufficient for the purpose in view were. under
my direction, ms de BY nv assistant Captain
B. D. Greene Corps OF Engineers, and Mr.. s.
l.. Fremont assistant engineer.
During the last year operations for improving
Savannah river and harbor were carried on in
conformity to the general plan submitted Au-
of March 10. 1879.
The leading object was to establish naviga-
bic channel from Tybee Roads to the CITY of
Savannah, practicable at high tide for vessels
drawing twenty two feet of water.
The original plan embraced the construction
of submerged dam at the Cross Tides. widen
ing the water way at the city front. and deep
ening, widening and Strengthening the channel
NV drado incy Al riOua F0ointQ haiom the Qitv
The cost Of these works was estimated at $751;
800
The supplementary project of March 10.
1879. had for its main object the improvement
OF the north channel in preference to the
south channel, from tie head of Eliza Island to
the head of Long Island. The new features in
troduced In this design consisted in the con-
struction Of low dam across the upper end OF
the south channel, in closing by dams the lat
eral channels now connecting the north and
south channels, from Elba Island 70 COckspur
Island, and in providing for shore protection at
some points 1t was proposed also to enlarge
the ship channel by dredging to minimum
depth OF l416 or IS feet, and a width OF rs feet
at mean low water, on all shoals between the
city and Tybee Roads. a design which essen
TALLY was embraced In the former project.
In both projects it was Indicated that other
works would be needed. chiefly for the reason
that the river is excessively wide It various
places below the city, and must be contracted
by suitable works to secure the preservation
Of the deepened channel, but no estimates for
works Of channel contraction were submitted.
In the present report it is proposed to point
out the places where the waterway should be
contracted; the works to be constructed for
that purpose, and other operations to be car
ried out in order to secure the end In view and
not embraced in previous projects, with an
estimate of their probable cost. Separate re-
ports of the examination, with general esti
mates Of cost, have been received by me from
Captain Greene and Mr.. Fremont, and will first
be referred to.
Captain Greene is of the opinion that to
secure and maintain deep channel down to
Tybee Roads will require the contraction of the
waterway the entire distance by means Of
wing dams and training walls suitably
distributed. His plan is essentially
as follows: The width of the
river between the limiting lines marked by the
heads of the combining works should be grad
ually increased from the city of Savannah
downwards. At the lower part OF the city it
would be $50 feet below the head OF Elba Is
land from 900 to 200 feet near Tybee Roads
from 1900 to 900 feet.
Captain Greene assumes that the desired end
consists in securing and preserving a mean
low water-depth OF seventeen feet in the navi-
gable channel from Tybee Roads 70 the CITY.
The following works, or sets Of works. he
thinks. should be constructed for the purpose
in addition to those already sanctioned.
1. Raising the dam at Cross Tides four or six
feet above the level Of low-water.
2. A training wall at the eastern end of
Hutchinson's Island, extending eastward about
a mile. with three spurs projecting from its
north side and three from its south side, the
heads of the latter to define the north edge of
the new channel at the Wrecks" Aggregate
length about 300 feet Of which 1890 feet is
for spurs.
g. A system Of wing-dams, eight In number,
to contract the channel and define its northern
margin from the lower end of Back river to
near the head of Elba Island; with a closure
dam on either side of Barnwell Island, giving
an aggregate length of works of about 7.400
feet. Of which length of $500 feet would be
occupied by spurs.
4. A dam closing channel between Eliza and
Spirit Islands. Length about ZOO feet. The
channel is also named Duck puddle.
IS. A system Of wing dams defining the north
ern and southern limits of the ship channel
from the head Of Elba Island to the lower end
OF Long Island. The set embraces six spurs
on the north side and seven on the south side
of an approximate aggregate length Of 1890
feet.
8. A system of training walls and spurs from
Cockspur Island to Tybee Roads The princi-
nal features are long SPUR jetty extending
south from Turtle Island towards Red Light on
Oyster bed Shoal. ana long training wall
with spurs on the north side of Saint Mchaeis
channel, which extends from Tybee Knoll to
Tybee Roads. Aggregate length OF works
% QUO feet, approximately.
Z. A dam across the south channel, about
half mile below the entrance of Saint Angus
tue creek. and low closure dam across that
creek near its mouth. Aggregate length about
1880 feet.
8. Three spur jetties on the northeast shore
OF Tybee Island, aggregating about 5, 400 feet in
length.
g. shore projections Captain Green indi-
Gates four places where the shores Of the north
channel should be protected to any considera-
bic length. VIZ:
a. South Carolina shore, opposite
Spirit Island ...................,. AGO feet.
b. North shore of Elba Island near
its lower end. .....:.......:..... 1900 feet
C. Jones Island, at and above Venus
Point 49,: ........-.......:...:. 1900 feet
d. Northeast shore of Long Island
central portion. ,......19....,.... 5000 feet.
Total length, approximately IA 500 feet
The total length of these various works
would be 81 COO linear feet, approximately, to
wit:
Training walls CHutchinson's Island
and Tybee KnolD. ...............2 30. 900 feet.
Spur jetties, except at Tybee Island 40. 400 feet
Spur jetties at Tybee Island ....... $500 feet.
Shore projections, as enumerated. IA, 500 feet
Closure dams DUCK Puddle South
Channel, St. Augustine creek. 80. AGO feet.
Total ACKNOWLEDGEMENTS. $4,000 feet.
As to the height of the wing dams. CAPTAIN
Greene recommends their heads to be three
feet high above low water, and their fhore
ends up to level Of high water. The heads to
be of 7 shape, and the banks near the roots of
The spurs protected. He says nothing about
the height Of the closure dams embraced 10 his
plan, but thinks that the dams closing the late
raj channels below Elba Island previously an
water, with the possible exception OF the dam
at Philbricks Cut, at the lower end Of Elba
Island
Dredging would be done in the vicinity of the
dams where necessary, and the material
dumped behind them. He deems it of the
greatest Importance that government should
procure and own a suitable dredge for that
purpose.
The materials Of which the works are chiefly
to be constructed to be logs, brush and stone,
in the most economical proportions, employing
stone as sparingly as consistent with safety.
AS the best method for performing the work,
he suggests buying material in market and
putting it in by hired labor.
The total cost of all the works described or
designed by Captain Greene is estimated by
him at $500, 900, or near that sum. The sum to
Island, opposite the city, is not included in the
estimate He thinks it quite possible that the
works will not at once be required of the
height indicated by him. but that in time they
will be. The purchase of plant for carrying on
the works OF construction is estimated at 800
900; the purchase Of dredge, tug, dump-b boats,
etc, at S35, OOO
Mr.. Fremont thinks that the waterway of
the north channel, from below Spirit Island to
below Venus Point, should be continued at
about the same width that now exists between
Spirit Island and the north shore, or about
I COO feet the contraction to be effected by low
dams, perpendicular or parallel TO the direc-
ton Of the current from or along both shores
If spurs are used. he recommends maximum
interval between them Of 500 feet, which, if
needed, may be reduced by supplementary
works.
North of Cockspur Island he recommends
the construction OF two training walls. One of
them would extend from the Horseshoe Shoal
to the Red Light Beacon on Oysterbed Shoal;
the other along the north side of st. Michaels
Channel.
clude some dredging, is estimated by him at
R3S0 000