Evening star. [volume] (Washington, D.C.) 1854-1972, 1894-10-16
THE AQUEDUCT BRIDGE PIERS
Major Davis Report on the Work of Re-
pairing
The Contract That Has Been Let-The
Way the Piers Were
Weakened.

MAJ. Davis OF the engineer corps, IN a re-
port made to the chief of engineers in re-
gard to the repairs to the Aqueduct bride,
says:
On September 1, 1894, the construction
Of a sounding raft was in progress. This
was completed and towed to the Aqueduct
bridge. and on September 8 the photographic
survey of the bed OF the river about pier
No. 4 was commenced. BY means Of a
carefully graduated sounding rod. the lower
part Of which was OF round iron. accurate
sorndings were taken from the raft in sue
cessive carefully located positions at in
tervals of two feet In each direction around
the pier and over the entire area which
would be occupied by a cofferdam. The
soundings show not only the depth to solid
rock. but the depth Of any everything mud
or sand. The object of this survey was to
obtain an accurate delineation of the con-
tour of the rock bed of the river in order
that the timber cofferdam might be framed
before sinking, so that II would fit the rock
and thus insure a comparatively tight joint.
The survey was finished September IL,
1894, and the soundings. some 4,5oo In num-
Der, have since been plated.
The general depths at low tide to rocS
were found TO be as follows: on the up
stream or west of the pier, thirty feet; on
the north side. twenty-five feet; on the
south side, twenty -four feet; on the down
stream or east end Of the pier, twenty
three feet. This survey and the previous
examination developed the fact that the
str atum of mud formerly everything the
rock and In which the original cofferdam
was founded had been practically swept
away by the action of the river current,
probably during freshets, increasing the
difficulties of the work and making II neces-
sary to build cofferdam of cribwork in
stead Of one OF round and sheet pailing,
such as was used in the construction OF
the bridge.
issued TO contractors engaged in the con-
struction of submarine foundations, de-
scribing the condition of the piers and the
work to be done in detail, accompanied by
piers, the depths of water, &c, at pier No.
4. and inviting proposals for repairing the
piers. The proposals were received on Sep
tember % and submitted to the chief of
engineers on the same day. The contract
was awarded to the lowest bidder, the
Smaller & Schniglau Company OF Chicago,
Ill, and was entered into September %.
The total amount of the contract based
upon the estimated amount of masonry TO
be replaced In the defective piers, is S33, 765.
The contract provides for the repair of all
the defective piers. Pier No. is to be
repaired by means of a crib cofferdam,
consisting of a heavy timber crib filled
with stone, surrounding the entire pier and
made water-tfght by means of Wakefield
triple lap sheet piling driven around the
outside of the crib and down to the rock
o
trusses resting on pier No. will then be
supported by trestle work so as to be in
dependent of the pier, to insure immunity
from accident during the progress of the
repairs. Before pumping out the dam the
overhanging masonry of the ice breaker
of the pier will be shored up by a diver 10
prevent the possibility of the fall of any
part of it when the buoyant effect of the
water is lacking. The dam will then be
pumped out and kept dry and the defec-
1--WE masonry Will be removed and replaced
by new masonry laid in Portland cement
mortar. The contractors took fmmedia te
action for the commencement of the work
DurlnS october they will place orders
Ior their material, secure wharf and con-
struction yard, and commence the repair
or ths piers where the concrete Is to he
put In place by a diver A large amount
of heavy timber will be required for the
crib conerdam, but a small part of which
can be obtained in this market. Ii Will
therefore be necessary to Lurchase most
OF the timber in Georgia, and bring IL to
the work by water, which will require sey-
eral weeks. The crib cannot be brilt until
this shipment OF timber arrives, although
all the work practicable will be done with
the timber, which can be obtained here.
The approved project provides for the
repair of six OF the piers of the bridge
which have been eroded near their founda-
tlons by freshets. Piers Nos. =, 3, 6, and
3 winch are not seriously injured are TO be
repaired by means of concrete In bags nut
In place by a diver. Pier No. 4, which Is
seriously injured, is to be repaired by
means of cofferdam, from which the wa
ter is to be pumped, and the e-odeJ mason
ry then replaced During the progress of
this work the spans resting on the pier
are to be supported by false work to pre-
vent possible danger to the superstTuc-
ture. The amount appropriated for the
work is Sol,OiO; of which. including existing
contracts. there is still an available bal
of $lb.g19.