The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-07-11
SOBWAY BUILDERS MASTER TASK
IN THE WILLIAM STREET MARSH
n eminent engineer suggested a

'''' hDi A'W ytats
aEo. His intention was to IL
lustrste a theory rather than to ad-
,ancs a practical proposition. As he
put T.:
AN enemy need not bother muster
ing ba%ttleships or waste his time bonn
harding from afar the intellectual Hub
Of this land of ours. In time of peace
let him have his spies build n big
pumping station right in the middle
" that city and at the proper time
start drawing indiscriminately from
the ground below the water saturat-
ing the subsoil. You know a very
laAIe part Of Boston's big buildings
rtsss upon floating foundations. Pump
out the water in the supporting quick
sand. and down those structures would
tumble into the yawning cavities 30
created II would be far more ef-
fcctive IN ~, demolition than the pro-
iectiios of a hostile feet!"
, somsNhat similar ida occurred
10 a good many OF the property own
ers along William street when the
plans for the ne.y subway were under
discussion. Their holdings have an
assesAd vsSue Of $40, 600, 200. and 1t
was not pleasant to think Of what
might happen when the contractors
reached the stratum Of quicksana.
Their anxiety provoked all sorts OF
arguments against running the sub
vay through that narrow street. In
the end the Pubic Service Commits
sion WA 80 well convinced hat the
work could be done without needless
ha1a-A tbot ~ ,SSnpnnl r.S,N.u4.hflltx
for any resulting property damages.
To-day quite twenty-three per cent.
Of the ~excavat!ng is an accomplished
fact; the public scarcely realize what
is taking place beneath their feet, and
none of the adjacent skyscrapers has
SagGed a hairs breadth.
The municipal engineers have
learned much during the years that
have interviewed since the first sub
way was built. and much other tnfor-
nation has come to them in connec-
ton with the construction of Manhat-
tan's towering office buildings. 1t was
this accumulation OF knowledge that
gave the experts courage to tackle the
exceptional task which the william
street subway represents.
The street is very narrow. the
foundations for the fanking structures
are shallow and the loads upon these
foundations are enormous. As a mat
ter Of fact some Of these buildings
lay a burden Of from thirty TO forty
tons upon every linear foot Of their
substructure, and in some cases where
the load Is distributed upon piers as
much as from 500 or 800 tons is on
$1,000. .;~al. columns II Ia
evident that under the best of condl-
tons IL would be a perilous matter to
burrow Unfortunately below these
supports, and yet that IS exactly what
the contractors are doing to-day in
the prosecution Of their work AS
one engineer expressed II, w snail
be upon the firing line when we get
Town to the foundation limits OF
these buildings, and just as nature
may change in her mood or state there
so must we muster our forces and
alter our attack and defence. we
must carry on our backs. as 1t were,
the burden OF the fianking buildings
while We form the walls OF the sub
way which, when done. will be rigid
enough to hold in place the supporting
groundwork of the ~skyscrapers.'
In order that the layman may I'M
,erstand the peculiar conditions h n
have to be met in digging the William
street subway it is needful TO give
some idea of the physical conditions OF
the ground below the street level. The
tunnel has To make its way through
sand and gravel and ~quicksand and at
no point will solid rock offer a resting
place. The ~eXcavatOrs are working In
The midst of the pr!mordial. Il each
loot Of advance confirms the findings
o' the preliminary explorations. Ac-
!rord!ng to John H.. Madden, the assist
ant division engineer, conditions are
those demanding the incest sort OF en-
cheering skill.
From the borings made rock was
Shown as lying from forty-six feet to
over one hundred feet below the sur
face. and /. is explained that the re-
treat of the glacier which nce COW
cred this territory and terminated in
the vicinity of New York had been
followed by the formation over the
rock outcrop Of a layer Of hardpan,
consisting OF broke rock and detritus
cemented with clay.
The water from the ocean had ad-
vanced, covering the lower section of
Manhattan Island, and the fine sane
carried by this ocean water had set
ted until the thickness OF the bed
reached the then water level. The
everything, coarser layers were subse-
quently formed from inland sources
The first deposit Of sand was water
worn and saturated, having very fine
grains from o~ne-hundredth TO one
thousandth OF an inch in diameter. re-
temhling. when flowing, a heavy dense
liquid.
A part OF the William street subway
must traverse a section OF the city
Known to civil engineers as "the
marsh" and semi-liquid sand abounds
mere in pockets. So long as the stuff
Is confined It Is not a menace to super
posed structures and, in fact, It has a
notable supporting capacity, but the
PERI les IN tapping these pockets and
Ft!nF the stuff run away. Techni-
'aLF this IL the material commonly
called quicksand. Mr.. Madden says:
This is the blanket OF quicksand
encountered below water level in the
""er sections Of the city. It's name
'omes from a German phrase which
uNNla,eo. means swimming sand.
"hlie this sand would settle in the
water II the latter were absolutely