The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1891-06-17
LAKE UNION TUNNEL.
The Shaft at Republican and
Lombard Streets Finished.
MODEL MECHANICAL APPARATUS.
What IL Being Done Mt the Mouth Of
the Tunnel at the Foot of
Depot Street.

visit to the Lake Union sewer tunnel was
paid BY City Engineer Albro Gardner and 9
observation-disclosures reporter yesterday after.
noon, and the work was found to be progress.
ing very nicely. The seven-foot shaft, at the
intersection of Lombard and Republican streets,
in the low level stretch there, has been compile
ted to depth OF sixty feet, and has solid cir
GUAR wall of concrete one foot thick. This
concrete wall is pronounced by Mr. j. f. Wit
mer, assistant city engineer, who has charge oil
the tunnel operations at the shaft.
as being of quality equal to
that celebrated material of which
the old Romans constructed their sewers. and
with which they paved the Appian way. 1t is q
combination of Portland cement, sand and
gravel, and Mr.. Albro Gardner, the CITY engi-
neer, says il is the intention to wall the tunnel
with IL The method of walling up the shaft
was TO mould the concrete in segmerts about
two feet in length and one foot thick and lay in
the shaft, twelve of these segments completing
the circle, and the wall being pressed down
from the top as fast as exeavated at the bottom.
II was on the whole a remarkably fine piece of
engineering.
Mr.. Wilmer has altogether about twenty-fiye
men at work in three eight-hour shifts two ex-
perenced miners digging in the tunnel, which,
now that the shaft has been completed, has Just
been commenced toward the Lake Union direc-
ton. Thus six practical Welsh miners are en-
ploycd in the distinctly mining features, the
other men being carpenters helpers or what
ever may be required. The length of the tunnel
westward from the shaft to the foot of Depot
street, at the beach, will be about 5000 feet; the
other portion of the tunnel, running eastward
along Republican street and terminating in the
low ground about 200 feet east of Rollin street.
TO be about 1000 feet long. This will make a
tunnel several hundred fee over mile in
length
The tunnel is 10 be cut to an average diameter
of six feet, and will incline toward the ives.
about one foot to every 200 feet or fall to the
bay of nearly five feet to the mile. Good hard
pan has been struck, mixture OF sand and
gravel.
The elevator to be placed in the shaft is all
ready, and the hosting will be done BY means
of a twenty horsepower engine, which was
made in this city by the Washington Iron Works
This engine also keeps the pumps going, thereby
keeping the shaft clear of water. The hosting
derrick was made here also. railway, two
foot gauge, is TO be laid along the bottom
OF the tunnel with sixteen-pound "T'' rails, and
over this track the dirt is to be conveyed from
the breast to the elevator by means of dump
cars These dump cars will have capacity of
about cubic yard, weighing about ton, and il
is expected that when everything is in good
running order about thirty of these cars will be
loaded every twenty-four hours, thus cutting
about fifteen feet of tunnel daily. The cars are
now being made on the ground, as all the other
apparatus of wooden material has been. The
work on the shaft commenced about two months
ago. but there have been several unavoidable
delays.
Mr.. Gardner and the reporter then walked
over to the mouth of the tunnel at the beach A
force of eleven men is kept at WORK in three
eighthour shifts, including the all-around me-
chanical genius, Mr.. Joe Stevens. the foreman.
For go feet the earth has been penetrated hori-
I1r ~Ho
work OF excavation up to about Temperance
street. Two men are kept constantly at the
breast and one man at the dump car. About ten
hneal feet is taken out daily. A railway for the
carrying out of the dirt to the beach is laid as
the work progresses. The track and the cars are
the same as have already been described. The
cars are SO arranged as to dump either front
or sideways. The tunnel at the mouth is
about seven feet in diameter. It is about fifty
feet below the surface at this point. Air is sup
piled TO the workmen by means of three horse
power Sprague electric motor engine, Smiths
improved air fan and wooden box to convey
the strong current of air to the breast. The
motor has velocity of about 1,400 revolutions
to the minute, while the fan turns about Zoo
times minute. 1t is model machinery in
deed. and very simple, not requiring any en-
gineer in attendance-simply little turn of q
couple of levers and the fan stops or starts, as
the case may be.
Some difficulty was experienced with about
eighty-five feet of sand, dry and loose, which
necessitated the construction of walls and roof
ing, the posts and caps, sxss. being about six
feet apart. Two-inch planks for tagging were
driven as the work progressed. There Is no
trouble, however, with water. At the beach q
yard, fifty feet broad, is being constructed out
into the water with the dumped dirt,
it being the intention to run this yard out
about 300 feet. This viii provide ample room
for concrete making, and the other work neces-
sary for the rapid completion of the tunnel
The tunnel will be at its deepest in the vicinity
of Oak street, where it will be about 40 feet be-
low the surface.
Between twenty-five and thirty lineal feet
daily will be the rate at which the tunnel will
be cut through when everything is running
smoothly, that is, when the work can be done
with as much facility at the shaft as at the
mouth of the tunnel