Evening star., 1895-07-12
THE AQuEDUCT BRIDGE
Major Davis Makes Report on the Weak
Pier.
Surprising discovery Made Poor
Work Done In Building
the Pier.

to the chef of engineers OF operations
under the project for the repair or the
Aqueduct bridge during the fiscal year
ended June 80, many of the early details
of which, including mishaps and dif11cultles,
have appeared in The Star from time to
time as the work progressed. During June
the repairs to pier No were continued.
The dam was satisfactorily tested during
the first five days of the month. Since
then the dam has remained in good cohdi-
ton. The leakage has been uniform and
is easily handled by the pump. Much OF
the water comes from springs IN hssures
in the rock, which yield clear water when
the river is turbid. One of the springs is
sulphur spring.
The overhanging masonry OF the Ice
breaker was removed In order tnat the
reconstruction OF this part OF the pier
might be safely prosecuted. Ihls masonry,
which was just above the eroded caVlty,
was found to be well laid in lime mortar
and was removed with some dfftlculty Ihe
removal of the debris below this cavity
was next undertaken. The excavation was
carried down to solid rock and as far down
stream as the first line of cross braces OF
the original Golfer dam of 1883. which t1m-
bers, twenty-one in number, had been left
in place and built into the masonry OF the
pier.
A Surprfsins Discovery.
AS this work went on an unexpected and
surprising discovery was made. 1t was
found that the old masonry had not been
started from solid rock, as shown on the
original plans, but upon rip-rap stone, ap-
parently thrown In without removing the
debris upon the rock. Layers OF mud ana
sand were found under the lowest OF the
old shores, while lying on the rock diago-
na1ly under the masonry OF the pier an Old
tree was found, which must have been
there before the pier was built. For some
twelve feet above this insecure foundation,
Maj. Davis says, the masonry Is of the
n % nj a
OF the name of masonry. The stones We're
apparently put in as they came from the
quarry. without the slightest reference to
beds, being set on end, edge and in every
conceivable manner, while few, if any.
traces of mortar or cementing material
were found. AS the level of low tide is ap
preached, however. the quality of masonry
improved. and from a level about six feet
below low tide up to the top of the pier
the masonry, while rough in appearance,
Is strong and a fairly good quality of rub
Bile masonry.
An Inspection in June.
The acting secretary of war and the
chief of engineers made an inspection of
the pier June "a last. and in view of the
poor quality of the masonry at the base
of the pier, it was decided that after the
completion of the present contract Cfor the
upstream end Of the pier) it would be
necessary in the near future to remove the
defective masonry in the remainder of the
pier and replace 1t by masonry of proper
quality founded on the solid rock. The ex-
listing appropriation will be insufficient for
this purpose. and 1t will therefore be neces-
sary to ask further appropriation from
Congress. The caferdan will be needed
for the proposed, work. and 1t has been
purchased from the contractors at a cost
In order todexoavate to and start the
foundation for the new work on solid rock
1t was found necessary to build an inner
dam Of sheet. pifing three inches thick
H.
end Of the pier. rThis dam reached to a
level some SIX feet below that drained by
the large pump, and steam siphon was
used to keep 1t clear. This small dam
the water, butwas held on June 20, so that
the excavation could be carried down to
solid rock. --'N
The lowest leveI of the bed rock was
probably never before been exposed. Sand,
mud. logs and loose stone were found over
lying the rock. The bed rock was found to
be very irregular and covered with small
projecting spurs or ncdules, with corre-
spending depressions or valleys. The gen.
eral level of the rock plateau uncovered
was about twenty-four feet below low tide,
but at the extreme upstream end of the
base of the pier as it is to be rebuilt,
deep cavity was found, curving under the
cverhanging shelf of rock. forming small
cave, the lowest part of which is thirty
one feet below low tide.
To he Replaced by New Masonry.
Major Davis says in conclusion that 1t IS
expected that the eroded portions of pier
No. 1, which have all been removed, will
be replaced by new masonry, and the re-
pairs completed as far as can be done
under the present contract, soon after the
close Of the fiscal year. when the dam will
be allowed to fill, and put in condition TO
Withstand the winter ice and spring fresh
cts. A project for removing all Of the
remaining defective parts Of the pier will
be prepared. with estimate of cost with a
recommendation for further appropra-
ton by Congress sufficient to completely
and satisfactorily repair the pier