Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1913-11-04

AS the Chagres river every year dis
charges enough water to flll the lake.
some means Of disposing Of the sur
plus water had to be provided. The
plan adopted called for spillway to
be constructed In this hill, about third
way in the dam site. This spillway Is
Of concrete. requiring 225,OO0 cubic
yards to complete On July I, 1913. 1t
was more than 9S per cent completed.
The floor Of the spillway Is ten feet
above sen level and 300 feet wide
through the hill. which involved ex-
cavation through rock for depth or
100 feet ut the highest point Of the
hill. A concrete dam was built on
this floor to height Of sixty-nine feet
above sen level and In shape Ike
semicircle On top Of the concrete
dam piers were built with an arrange
ment for steel gates These steel
gates will be electrically operated and
regulate the flow Of water out OF the
lake. AS much as 10000 cubic feet OF
water per second may escape through
the spillway when the gates are open.
There will not be complete loss OF
this water, as on the east side or the
spillway q power plant Of the hydro
electric type will be operated. A drop
Of seventy-fve feet by the water Will
operate turbine engines. which In turn
will operate the electric machinery that
will generate all the power and illumi-
mating current needed from one end or
the canal to the other. But an addi-
tional power plant will be maintained
pt Miraflores for emergencies. The
power to operate the lock gates VIII
come from the spillway plant.
The Gatun dam Is so stupendous that
II almost seems to be q continuation OF
the hills that inclose the lake. 1t In
fact does complete the natural noun
tain chains that form the barriers OF
the Chagres river. 1t Is l05 feet high.
or twenty feet above the ordinary level
of the lake mt eighty-1ve feet eleva-
ton. The plan Of construction has
been to build parallel mounds for the
mile and half. | 200 feet apart. Be
tween these mounds. built OF rock and
earth, q core for the dam has been con.
structcd by pumping mud and sand
from the bed Of Chagres river. About
90 per cent of the material pumped is
solid matter and when II has deposited
the water Is pumped of. This opera
ton has been repeated until an imper-
vious heart has been made In the dam.
Even IL water from the lake penetrated
the outside walls Of rock and earth II
would find this core water tight. The
dam Is nearly half II mile thick ut the
base. 39S feet thick where the water
surface strikes II mt eighty-tive feet
and Is 100 feet wide ut the top. The
outer coverings OF rock and earth Oh
the dam close over the hydraulic core
at the crest. For about 500 feet the
dam will be subjected to the full pres
sure of eighty.fvc feet Of water, mt
other points to II less severe pressure.
Engineers consider the dam exces
sively safe. and the layman has no diff
6culty In apprecinting It's strength.
About half Of the material required.
22.5O4OOO cubic yards. has been
brought from the Culebra cut On July
1, 1913, the dam was more than 90 per
cent completed. leaving less than per
cent to be done before the passage Of
the first ship.
On the Pacific size the first dam to
be encountered Is Mt Pedro Miguel and
serves to hold the waters Of Gatun
lake. ut Its southern end. 1t is l.4OO
feet long and forty feet wide ut the
top. The maximum height Of the water
against this dam will be forty feet
The plan Of construction is much the
same as at Gatun. but only 100000
cubic yards will be required.
After a ship is lowered thirty feet
by the Pedro Miguel lock 1t finds IT.
self In an, artificial luke n mile and
halt long. This lake Is formed by two
dams, the one to the west being 2,300
feet long and forty feet wide Mt the
top, holding n maximum head Of wa
ter Of forty feet. 1t Is constructed with
a hydraulic core like the Gatun dam.
On the east q concrete dam 500 feet
long and provided with spillway, as
at Gatun. and capable Of discharging
1900 cubic feet Of water per secoid
will hold the small lake in control
The Cocoli river Is the principal feed
ar Of this lake.
Records kept by the French and by
the Americans since 1904 show con
clusively that enough water always
will he available to keep the Gatun
lake and the tiny Mirafores lake nde
quntely supplied with water No trou.
bic at all can develop during the eight