Montgomery County sentinel. [volume] (Rockville, Md.) 1855-1974, 1911-02-03
Millions OF Gallons OF Water Lost
At Cabin John Bridge.
From the Washington Star.

Az $hDln JOhn Bridge.
From the Washington Star.
Two million gallons of water day
leaking through holes in the aaueduct at
Cabin John bridge and cracks and breaks
in the masonry which threaten that struc-
ture as well as the water supply of the en-
tire city are pointed out in detailed ac-
count of the aqueducts precarious condi-
ton, made by Lieut.. W. c. Langftt, Corps
OF Engineers, U. S. A., and forwarded to
the chief of engineers, U. S. A. 1t is esti-
mated that $4,000 must be procured to
make the bridge and conduit safe, and that
$4,000 must be made available. For
that reason it is likely the Commissioners
will be asked to get this item included in
the present appropriation bill. Calculations,
measurements and descriptions, together
with photographs showing the water which
is wasting from the bridge section of the
aqueduct, have been prepared by Lieut..
Langfitt and will be forwarded through the
proper channels to Congress, it is under
stood.
1T is believed" says the engineers re-
port to the chief of engineers, U. S. A., that
the application of the necessary remedy
should not longer be postponed. At the
time of the submission of the estimates in
the annual report from this office it was
realized that permanent repairs would soon
be necessary, but estimates were not then
submitted because the manner of repairing
the bridge in the most economical manner
had not been determined
ut is now proposed to place within the
bridge metal lining, either of a steel or
iron tube eight feet six inches in diameter
surrounded by concrete, or by the placing
of castiron sectional lining eight feet in
diameter, similar to that in the Washington
aqueduct tunnel under Rock Creek Either
method would be satisfactory and would
render the bridge watertight, thus pre-
venting the disintegration of the masonry
in the faces of the bridge, caused by the
freezing of the water in the Joints and in
terstices, and would check the deterioration
of the conduit now in progress The plan
adopted would depend upon the prices re-
ceived for furnishing the materials neces-
sary under the two methods and also upon
the convenience of installation with the
least interruption to the water supply"
The report says that the aqueduct has
one of its weakest points at Cabin John
bridge, and should break occur there
serious result would follow. because of the
limited storage supply of water. The pres
ervatiOn. therefore. of Cabin John bridge
is essential to the permanence of the wa
ter supply of the District. an interruption
at this point being likely to cause a short
age or failure of the supply in this city"
When water was first admitted TO the
conduit from Great Falls in 1868 leaks
were found in the big pipe when there
was seven feet of water in IT, The water
was drawn off and the lower half Of the
conduit plastered. and after that no leaks
were observed for some time, as the water
flowed within the limits of the plastered
section. The consumption of the city
water increasing. il became necessary to
raise the dam at Great Falls, and the con-
duit has been supplying more water, the
flow line gradually raising. The upper
portion of the conduit. not being plastered,
began to wear away by the constant rush
of water. In 1905 ii was noted that NOR
hot. kn ~
away an inch in some places.
Experiments were started in 1905 to
find way to remedy the defects. Much
of the upholstered portion of the tube was
plastered with cement. but this did not
affect the leakage to any noticeable extent,
and an effort was made to cement the
whole tube. The leaks in the middle Of
the bridge were stopped, but millions of
gallons continued to waste away at other
sections.
During inspection" says the report,
long cracks in the masonry of the con-
duit within the bridge were noted on both
sides Of the center Of the bridge, the axis
Of the bridge lying almost due east and
west. These cracks were kept carefully
filled with cement mortar, and il was not
until the conduit through the bridge was
completely pastered that those in charge
of the aqueduct felt assured that most of
the leakage did not come through mortar
joints of the brick crown Of the conduit"
The report further says that brick rings
in the conduit are broken and that the
upper portion of the pipe is moving over
the lower portion at the rate Of one-eighth
Of an inch year, and that this action
would undoubtedly cause the collapse of
the conduit If permitted to continue.
The army engineers assert that while it
may take years time to make the de-
sired change in the Cabin John bridge, the
work can be prosecuted without causing
any material shortage in the District water
supply. That result will be accomplished
by filling the reservoirs and emptying the
conduit for a day or two at time and
then replenishing the supply in the reser-
voirs. II is only because Of these frequent
necessary interruptions that the proposed
work would consume so many months
time
The bridge was constructed in 1859 by
Gen. (then Captain) NJ G. Meigs Of the
army as part Of the aqueduct to carry
water from Great Falls to this city. It
has been generally considered one Of the
great engineering feats Of the world.
Souvenir POstals
Nicely cOlored Postals Of the various
Government Buildings, etc, can be had at