The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1889-06-08
A BARRIER OF EARTH.
No Engineer of Good Standing Would
Have Built 1t,

JoHNsTowN, Pa. June IA. M. Yelling
ton, with +. T. Burt, associate editor of the
Engineering News of New York, has COM
pleted his examination of the dam which
caused the great disaster here. Mr.. Yelling
ton states that the dam, in every respect,
was OF very inferior construction, and of a
kind wholly unwarranted by good engineer
ing practices thirty. years ago. Both the
original and reconstructed dams were of
earth only, with no heart wall and only rip
raped on the slopes. The original dam was
made In rammed and watered layers, which
still show distinctly in the wrecked dam.
Inc new end greatly added to its stability,
put was to all appearances simply dumped
In like an ordinary railroad fill, or, il ram
med, shows no evidence of the good effect
from 1t. Much of the old part is standing
intact, while the adjacent parts of the new
work were wholly carried off. There was
no central wall of puddle or masonry, either
IN the new or old dam. 1t has been the in-
variable practice OF engineers for 80 or 40
years TO use one or the other in building
high dams of earth. 1t is doubtful il there
is single other dam or reservoir in any
otner part OF the United States over 30 feet
high. which lacks this central wall
The reconstructed dam bears the mark of
great ignorance or carelessness in having
Deen made nearly two feet lower in the mid
die than at the ends. 1t should rather have
been crowned in the middle, which would
nave concentrated the overflow at the ends
instead OF In the centre. had the break be-
gan 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 when the water began
running over the centre, the sudden break
ing OF the dam would have been at least
greatly diminished and possibly prolonged
SO that little harm would have resulted. The
crest OF the OLD dam was not raised in the
reconstruction in 1881. The old overflow
channel through the rock still remains, but
owing to the sag of the crest in the middle of
tne dam only five and half feet of water
are IN 1t instead of seven feet, necessary to
run the water over the crest. The rock spill
way is narrow at best, and Is further con-
traoted by close grating to prevent the es-
cape OF fish, capped by good sized timber,
ana IN some slight degree also by the treste
foot bridge. The original discharge pipes at
tne loot OF the dam were permanently closed
when 1t was reconstructed This further re-
duced the possible rate of the maximum dis
charge. N-'
The net effect Of all these differences of con-
oltion was that the dam was not much safer
against excessive floods, apart from its in
Ierlor construction, then the original dam
would have been with crest of three and
one-half feet high above the bottom of the
lae rock spill way instead of seven feet. A
large amount of tfe old riprapping and slope
wall remains intacr and is of excellent quail
lty. 1t does not appear that there was anv
great amount of leakage through the dam
before 1t broke. The destruction came from
the 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 it.
The dam was y feet above the water with
two to one inside slope, and one and a half
70 70 one outside slope. 1t was 20 feet wide at
tne top. The rock throughout was about
one foot below the surface The earth was of
pretty good material for such a dam, if IL
was to be built at all, being of clayey ma
ture and making good puddle. To this
fact its standing intact since 1881 must be
ascrlDed. No engineer of standing would
tnat the dam was reconstructed one after.
~ years abandonment, made 1t especially
naru on the older part of the dam to with
stand the pressure of the water.