St. Paul daily globe. [volume] (Saint Paul, Minn.) 1884-1896, 1886-01-21
MORE ABOUT THE BRIDGE.
Those Who DON'T Want nc Give Rea-
sons why.

sons Why.
The board of engineers who are inyesti-
eating the Minneapolis stOle-arch bridge
difficulty, met yesterday in Major Aliens
office on Ninth street. Several opponents
of the bridge were present from Mime
apolis.
Engineer Cooley opened the case by re-
marking some facts which did not occur i'm
his report to the mill company, which was
i'm the hands of the board. The question is
mainly upon the effect of erecting piers or
other distractions in the stream. lie had
made Soundmgs from the head Of the ledge
TO the mouth of Bassetts creek, and found
q number of holes where the bed of the
river had been washed out by reason of
some obstruction in the current. In one
hole the scour had extended about ten or
twelve feet downward. There is actually
Scour in the bottom of the river in the sand
rock itself wherever an obstruction has
been placed. extending down from five to
fifteen feet. as found by the divers. And
there would seem TO be no doubt about the
certain scour in this case; what has been
done once is likely to be done
again under similar conditions. The
bridge piers will present an obstruction of
100 feet; it is for the board to say what will
be their effect. AS to the statement that
the water in the sand rock does not come
from the river, he believed that his theory
was correct. In uncOvering these hOri-
ZOntal water-bearing seams we are apt to
uncover or expose pockets, now filled with
loose, dry sand, which, if water Is permitted
10 enter them, form the loci of eddies,
which will eventually wash out the rock.
About IS, 900 cubic feet of water are run
ming each day in the North Minneapolis
fuDnaI anI fhic NUara al cnrfaca xyotar
it would have drained the marsh long ago;
il would have drained lake LOCO feet
square and - feet deep in the length of
time the tunnel has been running. yet the
tests show no draught on the marsh. This
water must come from the river through
the thirteen-foOt seam under the lime rock;
it shows no trace of lime, as would be the
case if it came through the lime rock. 1t
would be dangerous TO tamper with this
seam. If a connection exists between it
and the sand rock below, it is fair to pre-
sumo that the same connection would exist
further down, with all tunnels if an outlet
were provided.
MR.. RINKER'S REPLY.
Engineer Rinker spoke of the washing
out of the eastern abutment of the Manitoba
bridge some time since, and ascribed it to
the water getting in at high stage behind
the abutment and washing the sand rock
from beneath it. 1t was built on top of
the rock and not sunk below its surface as
is proposed for the piers of the new stone
arch bridge. Engineer Morris agreed to
this. The soundings, Mr.. Rinker continued.
showed from four feet of water and four
feet of sand and gravel compactly placed
upon the sand rock. and so hard that il had
TO be drilled out and could not be moved
with the sand pump, TO ten feet of water
and ten feet Of sand and gravel upon the
sand rock. The sand rock is generally
twenty feet below the water level.
AS to the water discharged from thenorth
tunnel. it was less than cubic foot
second, not a heavy discharge. There is
constant surface supply for this water, aside
from the marsh. This is shown by the sur
face sewer drainage. Water has been run
ming out of the Eleventh avenue south
sewer for three years which can be shown
TO come from the surface. The water in
the tunnel is harder than that in the river
so much so that it curdles soap and work
men do not use it for washing. Again the
supply from the weeping holes is grad
ually decreasing, and they are drying up.
Again, while the tunnel is increasing in
length, the flow of water is decreasing.
which does not look as if it came from the
river. This is all a matter of conjecture
of course. 1t was also stated that the
piers of the Manitoba bridge are at a greater
angle to the current than those of the stone
arch. The mean velocity of the river here
is about eght-tenths of foot a second, or
half mile an hour, which is an important
factor in estimating the scour.
Mr.. Frank Cook was present and gave a
few pointers regarding the old eastern
tunnel, and stated the he believed the sand
rock would suff ~ badly when a stream of
water came in contact with it. He attrib-
uted the washouts at the head of the ledge
10 the old brown pier which stood at the
head OF 1t. 1t seems to have been the inten-
ton TO build the tunnel nearer the river
than at present. 1t was moved further
back on account of the amount of wafer
that came i'm. and the strong public protest
against it. The matter of riprapping.the
bed OF the river was casually discussed. and
+. A. Morris said if the current is detected
the sand rock suffers, and he Substantiated
his claim by citing his survey in connection
with the Manitoba bridge. If the PROMISED
piers were built he thought they would
form eddieS, which would damage greatly
the river bed. lie didn't think CITY En-
gineer Rinker was right when he claimed
that the water in the tunnel come from the
surface, as he could find no source of sur-
face supply that would give such an out
flow as there was He claimed the eastern
abuttment of the Manitoba bridge was
washed out because it was laid on the top
of the sandstone, and the water crept in be-
hind it. Several minor matters were dis
cussed, and an adjournment till to-day was
taken.
The smoke Nuisance.
Some days since the mayor addressed
aOlnmnnicA finm Ia tn. cnri,nta finn nffnrnn,-