The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1890-11-21
DREDGING THE BAR OF
HONOLULU HARBOR.


and important works for private
companies on this and other islands
Of the group, has surveyed the bar
Of this harbor with view to its
removal, is going to the States to
make further inquiries as to procur-
ing the necessary machinery for
clearing a passage of thirty feet
deep through it, thereby enabling
the heaviest ocean going ships to
enter, and, when other projected
improvements are carried out, to
berth alongside the wharves Of the
city, and discharge and ship goods
as easily at twenty-nine feet draft as
they now can at twenty-one feet.
Mr.. Allardt is of opinion that |
from the time his final instructions
reach him to getting fairly at work
on the bar might be within, say,
four months, and that gwen the
rate of progress already realised
under very similar circumstances
in San Francisco and Oakland har-
bors, twenty-five working days of
eight hours each might suffice to
clear the entrance.
The first thing to be done after
the plans and specifications of the
dredge itself have been prepared
will be to build the scow here,
whilst the machinery is in course
| of construction in San Francisco or
elsewhere, so that neither shall
have to wait for the other, but as
the engines arrive from the Coast
they may be set up here, and the
work of dredging be begun at the
earliest possible time. Another pre-
liminary to be carried out here will
be preparing place Of deposit for
the material raised from the bot
tom.
An area of about ten acres will
be selected on the coral flats east
of the harbor channel, and this is
to be surrounded by a suitable re-
tanning wall and levee; on its ex-
posed sides q wall similar to those
built round tishponds, and on the
sides not exposed to the action OF
the waves Mr.. Allardt considers a
suitable embankment would be
sufficient. If the site at present
proposed be selected, about $500
feet of pipe will be required to
carry the material from the dredge
to the place of deposit.
The "modus operandi !" is thus
described in Mr.. Allardt's report tc
the Minister of Interior, dated July
10Th last: " The work is to be done
by what may be termed the by
draulic method that is, by pump
ing up the material in suspension
and transporting it by water car
riage through sheet-iron pipes tc
it's destined place of deposit, where
it may be allowed to settle. The
machine proposed to be used is The
p Won Schmidt Patent Dredge, anc
f consists of powerful steam engin,
and a centrifugal pump mounted
: upon a large scow. From
the bow of the scow is sus'
pended heavy boom with movable
Joint, having at its outer end {
rotary pillow armed with q number
of steel shares or cutters fastened
to its periphery. When dredging
r is going on, the boom is lowered tt
: the bottom, and the pillow is made t.
|. revolve with considerable velocity
/ in that way loosening the materia
t to be dredged. The material to
0 gether with large percentage o
e water is then sucked up through The
S suction pipe by means of the cen
n trifugal pump, then forced by tn,
It same power through the transport
j. ing pipe to It's final place of de
posit," there it is enclosed by tn,
levee or wall for holding back tn
t debris laden water until it has tim
n to settle, and then the clear waite
d runs back to the bay by one o
= more openings left in the levee.
y :" In this way large tracts O
e lowland on the shores of San Fran
t cisco Bay were efectualIy re
: claimed"
g The total cost of removing tn
: bar by this system is placed by
o Mr.. Allardt at $4,000 or if it b.
r found advisable to carry a part O
e the whole of the material to NOR
2 distant spot-a proportionate in
e crease Of cost for extra piping, etc
i or as Mr.. Allardt points out, havin!
S the scow and dredge at their dis
+ posal, the Government havin!
i cleared away the bar can turn