The Cairo bulletin., 1910-03-28
CAIRO DREDGING CO. IS PLANT
AND ITS WORK IN THE CITY

are duplicates Of those on the boat
Steam is furni he'd by two standard
tubular boilers 7e in. in diametet
and 10 ft. long. The discharge pit,e
from the boat plant connects directly
10 the suction OF the hore plant pump
Both boat aud hore plant use tie
Mississippi river water for boliel
feed and both plant run non-conleLs.
ing.
/ The length Of the pipe line from
the hore plant 10 the discharge was
about 1900 1t. when the filling com
menced and has been increased to
4,io0 it. with the progress of the
work. All pipe used except saeticn
land pontoon pipe il l2-in spiral rivet.
/ ed pipe, aphalted- Nearly all the
pipe is No. II gauge. but on the end
of the discharge line where the pipe
/, FequiTes frequent handling and light.
lness Is a prime consideration. some
No. IA and 1G gauge is used.
A private telephone lne connects
the boat. hofe plant and end OF dis.
charge pipe. and by it the suction
operator l. kept constantly informed
tas to the percentage OF solids carried
/ in the water and is THUS enabled to
regulate the supply 1t may be men
toned here that the surplus water
find its way to the river by means
OF the city sewers.
! The original estimates OF the cost
were somewhat exceeded and $4,000
was expended on the plant before 1t
! was ready for operation.
The plant was started late In the
sea on OF 1907 A number OF diff
Icnlties developed after the plant had
been In operation a hort time. The
lncst serious was the rapid wearing
lOf the shells of the dredging pumps,
These We're of cat iron and not very
thick and 1t was found that every
$4,000 Gu. yIs. pumped required
new set Of shells at both the boat
and the shore plant. This extreme
wear was are in part to the quality
of the material handled The Missi
sinpi river sand is very coarse and
sharp. The high speed at which the
pump had to be driven caused the
shells to cut out ia ter than most
sand pumps. X was found that, at
low water periods and when pumping
to the most di tant areas a periphera!
speed Of the runner of about $500
1T. Per minute had to be maintained
to produce the required velocity in
the pipe. Considerable trouble was
experienced with the pump shafts as
they wore very fast in the stufffng
boxa. and finally broke. As the
pumps were of the Idle suction tyne
great trouble was experienced in car
Ing for the end thrust of the runner
a great deal Of time and money
was spent in the endeavor to produce
a pump more suitable for the work.
Pumps with larger diameter runners,
and with renewable liners in the
hells were tried and at length a
pump was evolved that gives very
good satisfaction. The present pumps
which We're designed and built spec
tally for this work, are of the double
suction type to obyiate the end
thrust The runner are built up OF /
steel ca ting and A-in boiler plate
and are 81 ins. in diameter The
t1slft tc inc IN, n
The shells are coneentric with the
shaft and are heavy steel ca tings
The inside dimensions are It.. in
diameter and 10 ms. wide. The metal
in the shells is Ia ins. thick on the
sides and 2 ms thick on the circum-
ference. These pumps have given ex-
cellent service. A pair of them has
pumped 10000 GU yds. of sand and it
ls estimated that pair of the steel
shells will deliver 10000 GU yds. be,
fore wearing through. !
The 22-in. belts connecting the en-.
gines and pumps gave a great deal of
trouble. Canvas, rubber and leather
belts were tried. but none would
stand the severe service. At last
wire rope drive was installed in both
plants. This drive consists of the or
binary grooved pulleys and ten parts
OF A-in. wire rope. Each strand of
he wire is served with marlin which
produces a very flexible rope. This
transmission has given excellent ser
vice and has caused no trouble since
It's installation.
ahThe periods Of unusually high and
low water experienced the last two
years have proven great handicap |
to the work. At the extreme low
water, which has lasted for two or
three months in the fall Of the year,
the sand bar is entirely dry and the
boat is aground and cannot be moved |
to secure a supply of sand. Again at
high water which is sometimes AS IT.
above low water, the land outside the
levee and the trestle work to which
the rontoons connect is from 6 to 10
ft. under water The running ice