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NEW YORK, APRIL 4, 1914





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UNIQUE   FOUNDATION   FEAT  SAVES   TIME





Preparing Excavations for New Structure on Old Victoria Hotel Site, While Wreckers
Are Demolishing Hostelry — Engineering Problems Present Unusual   Difficulties

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THE fact that time is one of New
York's most valuable commodities is
responsible for an engineering feat never
before attempted. The foundations for
a new twenty-story mercantile building
are being placed while the original build¬
ing on the site is being demolished. The
building in question is to be built for
the 230 Fifth Avenue Corporation
(Johnson-Kahn Company), and is to oc¬
cupy the site of the old 'Victoria Hotel
at B'roadway, Fifth avenue and 27th
street, from plans by Schwartz & Gross,
architects,   of   347   Fifth   avenue.      The







ST.\RTI.\G PILES  THROUGH  FLOOR.

placing of these foundations simultan¬
eously with the wrecking of the building
it is calculated to save at least two
months of time to the owners, and
makes possible the completion of the
new building by January 1, 1915, in tin>e
for the rental season.

The Underpinning and Foundation
Company, 290 Broadway, took the con¬
tract for the work and gave a guarantee
for its completion in the time specified.
The problem was one which involved
difficulties of a serious and various char¬
acter. The new building will rest on
680 steel and reinforced piles. These
piles are grouped in 63 piers, each one
composed of from 9 to 14 piles, sunk to
a maximum depth of 50 feet below curb
level, and capped with a slab of concrete.
The piles being: use4 are known as the





"Hercules" steel piles, and are made and
placed under patents held by the Un¬
derpinning and Foundation Company.
They are heavy steel cylinders, with
walls f^ inch thick and an inside diam¬
eter of 12 inches. These cylinders are
driven to bedrock by means of a 3,000-
pound hammer. When the piles reach
bedrock they are blown clear of sand,
mud and loose rock by means of a com¬
pressed air blast under a pressure of 150
pounds to the square inch. The mud
and water displaced by this terrific blast
sometimes rises to a height of 150 feet,





A TYPICAL FLOOR PLAN.





a weight of six tons, and the completed
pile will sustain 100 tons, allowing 20
tons as a margin of safety.

Chief among the numerous difficulties
involved in the present operation was
the fact that the piles had to be placed
while the greater part of the old build¬
ing was standing. To do this it was
found necessary to cut away the floors
in the first and second floors directly
over the locations of the proposed piers.
The driving hammer is slung by chains
from the beams of the third floor. An¬
other  problem   encountered  was  water.





















DRIVING  PILES  IN  CELLAR.

and rock weighing as much as fifty
pounds has been blown from a distance
of 40 feet below the surface. After the
cylinders are cleaned out and the bed¬
rock exposed their tops are cut off at
exactly the same level. An oxy-acety-
lene torch is used in this operation and
the work is accomplished with dispatch.
Each steel shell is next filled with con¬
crete reinforced with three 2-inch square
rods running the entire length of the
pile,   pvery rod i? capable of sustaining





In excavating for the new piers a
branch of the underground stream which
flows diagonally across the city was en¬
countered. The tapping of this stream
practically flooded the working space
under the old hotel and made it neces¬
sary for the contractors to dig a sump
pit and install pumps to carry away the
water. The pumps, with a total capac¬
ity of 500 gallons per minute, were kept
in constant operation day and night for
two weeks, and the water level reduced
twelve feet. The old building had been
built on wood piles, but the constant
change of the level of the underground
stream had rotted away the tO;)S of
these piles and it was found to be rest¬
ing solely on earth, packed almost as
hard as concrete.

Another feature of the work that re¬
quired careful thought was the conliti in
of the bottom encountered. Instead af
locating bedrock at a uniform level, this
rock was found to shelve in an unusual
manner. In one part of the site it was
found to be less than five feet below the
old cellar level, while in the nearest pier
to this place, or about a distance of 20
feet, the contractors were forced to sink
piles forty-five feet before bedrock was
found. This cohdition made much drill¬
ing and blasting necessary, which was a
delicate operation considering that the
old buildings -above was in process of
demolition.

All the power used, both steam, elec¬
tricity and compressed air, is being gen¬
erated by the old power plant for years
used to serve  the hotel.

The work of driving the piles for this
foundation was started March 9, and the
entire foundation will be completed and
ready for steel grillage by April 10. A
force of ISO men, in day and night
shifts, have been employed from the
time tjie work was starte4. An open pit