The Superior times. [volume] (Superior, Wis.) 1870-1912, 1889-06-15
A VERY INFERIOR. DAN,
An Examination by Experts Of the So Il
Fork Embankment

Fork Embankment.
YOUNGSTOWN, Pa, June IA. NJ. Well
ineton, with F. p. Burt, associate editor
ofthe Engineering News, of New York,
has Just completed an examination of
the dam which caused the great dishst-
er here. Mr.. Wellington states that the
dam was In every respect OF very inieri-
or construction, and OF kind wholly
unwa rranted by good engineering prac-
tees OF thirty years ago. Both
the original and reconstructed dang
were OF earth with no heart
wall, but only rip-rapped on the slopes.
The original dam, however, was made
IN iammed and watered layers, which
still show distinctly in the wrecked
dam: The new end greatly added to its
stability, but it WAS to all appearance
simply dumped in like an ordinary rail
road till, or, if rammed, shows no evil
dence of good effect from it. Much of
the old part is standing intact while
adjacent parts of the new work are
wholly carried off. There was no CEN
trail wall Of puddle of masonry either in
the new or old dam. 1t has been the
invarlable practice of engineers for
thirty or forty years to use one or the
other If building high dams Of earth.
1t Is doubtful If there is a single other
dam or reservoir in any other part of
the United States nifty feet high which
lacks this central wall. The recon-
structed dam also bears the mark Of
great ignorance or carelessness in hav-
ing been made nearly two feet lower in
the middle than at the ehda. 1t should
rather have crowned i'll the middle,
which would have concentrated the
overflow If it should occur, at the ends
instead of in the center. Had
the break began at the ends the
cut of the water would have been
so gradual that little or no harm might
have resulted. Had the dam been at
once cut at the ends " hen the water be-
pan running over the center, the sud-
greatly diminished, possibly prolonged
so that little harm would have resulted.
The crest of the old dam had not been
raised IN the reconstruction OF 1881.
The old overflow channel through
the rock still remains, but owing
TO the sagglng OF the crest IN
the middle of the dam only 81
feet OF water in 1t, instead
OF feet, was necessary to run water
over the crest And the rock spillway,
narrow at best, had been further con-
tracted by a close grading TO prevent
the escape of fish, capped by good
sized timber, and in some eight degree
also by trestle foot-bridge. The orig
lnal discharge pipes at the foot OF the
dam had been permanently loosened
when reconstructed, and this, while a
minor matter compared to the others
mentioned, further reducedthe possible
rate OF maximum discharge.
The effect of all these differences of
condition was that the dam, as it stood,
was not much safer against excessive
floods, apart from its interior construc-
ton, than the original dam would have
been with crest only 81 to feet high
above the bottom of the rock spillway,
instead of feet. 1t is impossible 10
say if the rip rapping of the new part
OF the dam was rs good as the old or
not, since it has been entirely carried
away. A large amount OF the old rip
rapping and SLOPE wall still remain in
tact and are of excellent quality. 1t
does not appear that there was any great
amount of leakage through the dam be-
fore it brooks. Destruction came IRON
water flowing over the top.
Mr.. Wellington said that no engineer
of known and good standing for such
work could possibly have been engaged
on 1t, since in the particulars men
toned it violated the most elementary
and universally understood require
ments of good practice. He did not be-
lieve that any other dam of equal height
had ever been constructed in this coun-
try wholly of earth, without some spe-
cial protection against leakage by water
or abrasion by water in the center.
The estimates of the original dam in
dictate that it was made about half earth
and half rock, but if 50 there was little
evidence of it in the broken dam. The
rip-rapping was merely skin on each
face, with more or less loose spauls
mixed up with the earth. The dam
was ~ feet above water, to inside
slope, II to l outside slope; 20 feet
wide on top. The rock throughout
was about one foot below the
surface. The earth was pretty good
material for such dam, if it was TO be
built at all, being OF clayey nature,
making good puddle. To this the fact
of its standing intact since 1881 must be
ascribed, as no engineer of standing
would have tried to so cons ruct it. The
fact that the dam was reconstructed
alter twenty years abandonment it was
especially hard on the old part to with
stand the pressure of the water. Mr..
Wellington left for Pittsburg this even
ing