Evening star. [volume] (Washington, D.C.) 1854-1972, 1883-09-01

Work to be Done on the Tunnel. Reser-
vOir and DAM

washington aQueQucts SO as 10 increase the water
supply of this CITY, Is one OF great magnitude not
only in its extent but as an achievement OF en-
gineering. There are three separate and distinct
classes of this work. First the dam at Great
Falls; second, the construction OF q tunnel about
four miles in length, extending from the present
q distributing reservoir above Georgetown along the
ridge OF hills overlooking the northwestern part OF
the city to the proposed new reservoir east OF
Howard University; third, the construction Of this
proposed reservoir. more detailed description
OF tails work Will be of interest, as it is the iten
tiCn to begin the active work of construction this
fall. The land along the line OF the tunnel will
b. condemned and purchased by the government
at points where it is necessary, and the land oc-
cupied by the reservoir will be obtained in the
same way.
Four-Mile Tunnel.
The tunnel will begin at the distributing reser-
volr, above Georgetown, and is regarded by en-
gineers as an extension OF the present aqueduct.
1t will be about 2osae feet long, about II feet wide
and ~ feet high.
GEOLOGICAL FORMATION
The formation through which the tunnel will be
driven is believed to be a compact gneiss rock.
such may be seen in close proximity to the line
leys OF Rock creek and Of Foundry branch, where
two OF the working shafts are located, and else
where. At the site OF the east shaft trial shaft
has been sunk, and 1900 feet west OF this on the
line, a bore hole put down into the rock These
show the same characteristic formation which is
exposed at Rock creek. Foundry branch, and else
the surface, or where 1t has been Quarrled or
otherwise eXcavated.
LOCATION OF sHAFTs
-Four working shafts will be sunk simultaneous
ly to such depth as may be required, the object
being to penetrate the rock sufficiently to insure
continuous roof OF sound rock for the tunnel One
will be at the site of the present trial shaft east
end OF the tunnel, one at Champlain avenue one
at Rock creek, and one at Foundry branch. The
present surface, or 121 feet below bottom of the
new reservoir, within which 1t is situated: the
Champlain m avenue SHAFT, no feet: the Rock creek
shaft 40 feet, and the Foundry branch 46 feet be-
low the present surface. In addition to these a
connecting shaft will be sunk at the distributing
reservoir, at the western terminus OF the tunnel
to a depth. approximately, of 10 feet below the
surface. The east shaft and west connecting
smart, down to sound rock, are to be permanent
shafts, and will be finished, after the completion
OF work on the tunnel. by lining OF brlckwork,
concrete. and dry-stone packing fourteen feet in
tsrior diameter extending from the solid rock to
tne surface OF the ground.
AIR Shafts
Three air shafts will be sunk at different points
for the escape of confined air from the completed
tunnel, when running full OF water They will be
lined with cast-iron pipe OF four inches interior
diamter. These shafts will be hbout l30 1856 and
$50 feet in depth.
DRILLS DRIVEN BY COMPRESSED AIR.
The excavation of the tunnel with be effected by
means of the best quality of power drills, using
OF these will be provided to insure the continuous
work OF not less than four at each breast, and
they Will be of such capacity for work as to insure
daily progress In rock OF seven feet at each head
Ing The air Will be taken from the head Of each
four inches interior diameter with Joints made
@ aDsoiuLeiy secure against leakage and loss OF air
Hor Hono Of qng ha may be- used TO supplement the
provided at the head OF each working shaft, at
such pressure as to give not less than 80 pounds
proportions; at the east SHAFT not less than 125
cuolc feet per minute, at Rock creek shaft Champ
lam at , avenue shat. Foundry Branch shaft, each
consumed. 10 ~"A1 W o0''uN'
THE WORK TO BE PUSHED WITH v1GoR
1t Is expected that the entire work will be COM
pleted on or before June 80 1885. All work and
workmanship will be the best or its kind satisfac-
tory in every respect to the engineer, Major Ly-
decker. All operations will be carried on with the
utmost vgor, with ample force, and all necessary
machinery ana plant, of kinds best adapted to the
purpose, and required to insure the greatest pos
sible progress in the prosecution OF the work
ESTIMATE OF QUANTITIES.
Excavation in tunnel, 81, 900 cubic yards: earth
excavation in shafts 500 do rock excavation In
shafts. 200 do; brick masonry in shafts, $50 do
concrete masonry in shafts, $50 do dry-suOne
packing In shafts, 400 do: air shafts complete
40 lineal feet
The Construction OF the Reservoir.
This tunnel will empty its contents into the
reservoir to be built east OF Howard University It
Will holl not less than three hun1red million gal
Ions OF water. The amount OF excavation will ap-
proximate six hundred and nInety-flve thousand
cubic yards, the greater part Of which will be
placed on emDaDkment to form the dam across
the valley In which the reservoir is to be located
The east working shaft OF the tunnel is located
within the limits OF the reservoir. Rock excavated
from the tunnel will be deposited and will be used
contractor ar
TO divert the Water OF the creek now flowing
across the site OF the work. provide for the drain
age o! the reservoir, and 1ntercepte the surface
water from the surrounding country, the cOntrac-
tor will be required to construct the necessary
masonry conduts iron pipe draIps, and side food
the bu sdings trees, bushes &C.. from the area in
cluded within the flow line OF the reservoir and
covered by the dam, side channels or the auxiliary
works. he will also remove the sod aud soil to such
depth as may b. required, and preserve the same
the work.
Extension Of the Dam at Great Falls.
At Great Falls the work will consist ust> OF
raising the present masonry dam across the Mary
land channel OF the Potomac river at the Great
Falls oy coping fifteen inches thick; (2D the ex-
tension OF the dam across Conns Island by ma
sonry structure about 120 feet long with aver
age height OF about six feet; and (3D the further
extension OF the dam about 45O feet across the Wiz
gina channel by q sub-5tTucture Of crib work
Aiiou Will otouc anu il aSup3TSiFucCurc OI masonry,
together with about 800 feet OF masonry dam to
make connection with tbe Virginia shore. The
present dam at the Great Falls Of the Potomac
river Will be completed to level OF 14S feet above
Lide and extending the same to the Virgini shore.
me completion or the present dam Is to be accom-
pisned Dy pi aclng q stone coping fifteen inches
thick ana ABOUT 1,O6O feet long; the extension in
voiVes the construction OF a masonry dam across
COnn'S Island TO deep water in the Virginia chan
ne ana from the opposite side OF said channel to
the virginia shore, and OF crfb dam with ma
SOnry Superstructure across the deep water OF the
virginia channel The masonry dam In this ex-
tension Will have an aggregate length OF about
IeeC ana an average height OF about six feet;
tne crio dam Will be about $50 feet long, placed in
water whose average depth Is about twelve feet
ono greatesI depth nineteen feet at ordinary low
water stages. The work Will be commenced by
clearing the ground across Conn's Island OF all
trees, dri1t &C., along the line OF the dam for
width OF 1OO Ieet, and removing the same, together
win refuse or every kind. from this area In such
manner as TO prevent any interference with the
future progress OF the WORK.
Notice to tsuOney Sharksn
ACTING SECRETARY JOSLYN ANXIOUS TO PROTECT
THE - FOOLS IN THE INTERIOR DKPARTAENT.
Acting Secretary Joslyn said to STAR reporter
to-day. II wish you would say for the benefit OF
employees In the Interior department and Of the
money sharks that will not enforce the collec.
ton OF any usurious contracts made between
money lenders and employees OF the Interior.