Evening star., 1901-11-05
TUNNEL COMPLETED
End of a Work Begun Nearly Twen-
ty Years Ago.
WATER TURNED IN TO TEST IT
Aqueduct Nearly Four Miles in
Length.
EXPENDITURE OF MILLIONS

EXPENDITURE OF MILLIONS
The great tunnel to carry water from the
distributing reservoir on the Conduit road
to the large reservoir near Howard Uni
versity. nearly four miles in length, is COM
pleted and ready for the purposes for which
1t was constructed A test was made Oc-
tober 81. when the tunnel was partly filled
with water, sufficient to give height OF
eighty-nne feet above tide water. Novem-
Der the water was blown off to demon
strate if the tunnel would stand the strain,
the test being entirely satisfactory.
But for the fact that there is little
trouble at the pumps, which became clog
ged in the blowing-off process, the water
would be permanently let in the tunnel and
its great function begun. The cleaning OF
the pumps is now being done, and it is ex-
pected that the work will soon be finished
When this is done the water will be let
in and the reservoir at Howard University.
recently completed will be filed the supply
coming from the distributing reservoir on
the Conduit road, about four miles dis
tant.
The work Of completion was carried on
under the direction Of Col. Alexander M.
Miller. the engineer officer in charge OF
tifty-efght years Of age November l, the
day on which the water was blown off, and
instead Of feeling a year older, he felt
ten years younger. The test was entirely
successful. Ever since he has been in
charge of the aqueduct he has been hard at
work on the tunnel. and its completion lifts
a load of responsibility from his shoulders,
for which he feels extremely thankful.
VIII Stand the Strain.
Although the full pressure Of water was
not allowed in the tunnel at the test, there
Is no doubt Of It's standing the heaviest
strain to which 1t will be subjected. Though
only sufficient water was allowed to now
into the underground passage to cause
rise of eighty-nsne feet above tide level,
the pressure at some points, and especially
underneath Rock creek was something like
twenty-four pounds to the square inch.
When in full operation the water in the
tunnel will rise to a height equal to 144
feet above tide level, with a pressure of
something like fifty-four pounds to the
square inch. This pressure will be neces-
sary to fill the reservoir at Howard Uni
versity which has capacity Of 800, ,O0O, 600
gallons, and which Is designed to supply
the northeast high-pressure section with
sufficient amount Of water to meet demands
for some years. There is some water In the
Howard University reservoir, which was let
in from the forty-eight inch water mains
on 4th street. 1t was the intention OF Col.
Miller to fill the reservoir during the re-
carried out. but for the clogging of the
air pumps.
Duplicate Pumps.
The idea of the test was to try the 'blow-
off, of the tunnel. as well as to see how the
"flling' stood the strain. The tunnel is
supplied in two places with pumps-at
Champlain avenue and at Howard Univer
sity. At each of these places duplicate
pumps are established, the shafts for the
accommodation of the pumps being sunk
100 feet below the base of the tunnel itself.
This depth was made necessary to get suf
ficient pressure to blow the water off. Each
pumping apparatus consists of a large tube
encircltng a smaller iron tube. At the bot
tom there is a screen arrangement which
prevents large pieces OF dirt or stone from
entering the mouth of the tube. Air is
forced down the larger tube and at the bot
tom enters the inside tube, drawing the wa
ter up with It.
Originally there were four shafts sunk
one at Howard University, another at
Champlain avenue, another at Rock creek
and one at Foundry branch. With the COM
pletion of the tunnel another shaft was
sunk at the distributing reservoir. The
Foundry shaft is now closed, and may
not be used again. The one at Rock creek
will be covered UP, but arranged that 1t
can be used whenever necessary: The
shafts at Champlain avenue and Howard
University will be kept open, duplicate
pumps being located at each of those places.
Three Air Shafts.
There are three air shafts to the tunnel,
one located near the Western High School,
another at what is known as Widows Mite
and the third at 18th street. They We're In
stalled in order to provide means for an
escape of air when the tunnel Is filled with
water, thus guarding against possible acct
dents from compression Of air in the tunnel.
One Of the deepest parts of the tunnel is
near the Western High School, near where
the air shaft is located. The lowest point
however, is just beneath Rock creek, where
only twenty-three feet separate the top of
the tunnel from the bed of the creek At
the distributing reservoir the mouth of the
tunnel Is seventy-seven feet below the sur
face of the ground, while at lie other end
Howard University the depth is 15S feet
below the level Of the ground. At Howard
| reservoir water has been let in to the height
of 124 feet above tide level but when full
the measurement will be IA feet an in
crease of twenty feet.
Just where the tunnel crosses Rock creek
the former contractors in blasting used
heavy charges Of powder. There was only
slight thickness Of rock above the tunnel
at that point. The rock was seamy and
the blasting permitted large amount Of
water from Rock creek to flow in and prac
tically fill the tunnel. To remedy this an
iron cylinder was built in the tunnel under
the creek for length of about 800 feet
This solved the difficulty
The tunnel itself is approximately eleven
feet in diameter. 1t is generally of horse
shoe shape, but in some places that for
nation in construction could not be fol-
lowed. notably under Rock creek, where it
is circular In form. At one place the per
pendtcular diameter of, the tunnel is about
twenty-five feet. This is near 35th street
where there is a change in the grade.
Work of Reconstruction
The reconstruction Of the tunnel began
in July, 1898, when Colonel Miller assumed
charge of the Washington aqueduct The
total amount appropriated and available
for the reconstruction was 1898 1SO SO, and
the actual cost Of the work will come ex-
tremely close to the estimated cost The
work will be finished within the appropria-
tions. There had previously been app-o-
priated $2.575.279.3 80. The tunnel itself is
practically completed, except for some fin
ishlng touches. There will be some extra
work at the ends, especially at Howard
University.
The construction Of the tunnel was a
work OF great magnitude, and is regarded