The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1895-09-02
STORAGE OF WATER.
Few Practical Suggestions offered

10 the Editor Inc Herald.
1 notice in The Herald something
! in regard to storing water in reser-
Voirs, and as it is a subject of much
| Importance, I give few practical sug-
gestions derived from an experience
as q canal and hydraulic engineer of
over forty years. These suggestions
can only be upon general principles, as
so mL-h in the construction Of res
erVoir depends upon its location, height
of dam, and material to be used.
AS dams built of rock are 100 costly
to be built in communities of limited
means, and should only be entrusted
to skilIful and experienced engineers,
they are built only in exceptional cases,
and in this article I will refer only to
reservoir dams built Of earth. When
properly constructed earthen reSer-
voirs are good and reliable, as evil
denced by the fact that in India are
many thousands OF them which have
remained intact for generations. In
the Madras presidency alone there are
over 10000 of them, some of which
range from fifty to one hundred feet
in height. Most of them were built
long before the occupancy OF the coun-
try by the British.
In an earthen reservoir certain re-
quirements are absolutely essential,
the most important of which are, first,
a sufficient thickness of dam; second,
a height such that the water in time
of flood cannon flow over the top; third.
that its ends be so protected that wa
ter cannot cut around II, and fourth,
that a waste way or wier be provided
large enough in cross-section to carry
all the water that may come from
rains or SHOWS melting, or both, that
can drain from the entire area center
ing in the proposed reservoir. A neg
lect of this last provision caused tine
tremendous disaster at JohnstoWn,
Pa, a few years ago, when so many
thousand lives We're lost. An unusu-
ally heavy and long continued rain
occurred, and the waste weir was too
small to pass the surplus water. An
attempt was made to enlarge it during
the storm, but before it could be done
the gathering waters burst over the
top, quickly cutting a breach impossi-
BILE to close by any human power. If
possible a waste weir should be in
solid rock, but as often happens this
cannot be, in such case 1t must be pro-
tected by masonry, concrete or timber
and plank, that a heavy rush Of water
through it cannot undermine or cut
it down. Experience teaches that SUCH
a dam, impervious to water, and with
a sufficient waste weir is as reliable as
any other, unless it be one of cut
stone laid in cement and founded upon
solid rock.
An earthen dam should have a slope
of at least one and a half feet horf-
zontaI to one foot perpendicular, and
the slope next the reservoir should be
rip-rapped-ccvered with stone care
fully laid to prevent damage by the
wash of waves where the area Of the
reservoir IS large enough to cause
them. The best earth for dam is
a mixture of clay and gravel, but
whatever the material, it should be
we'll compacted. This is best accom-
plished by teams and scrapers, as the
horses trample it much more than in
hauling; larger loads OF earth in wagons
or carts Every railroad contractor
knows that an enlbankment built by
teams and scrapers is much more SOL
id than the natural earth adjoining.
In this dam there must be TO logs,
stumps, brush, turf or other persha-
BILE material, because after certain
amount of settling an embaukment
settles no more, and in time the. per-
ishable material decays, leaving cav
ity through which water may pene-
trate. If a willow or pole is long
enough to reach from the water to the
other side water will surely find its
way along its surface, and as the dirt
turns to mud and runs out below a
leak is formed, which increases until
it will destroy the dam if not cured in
time.
To prevent possible leakage or drain
age from muskrats or other burrowing
animals, the best engineers build a
thin wall in the middle of the dam,
from the bottom of it TO the top. This
may be of brick, stone laid in cement,
| concrete, or puddled clay. Thickness
in this wall is not so important as that
it be perfectly imperviouS to water,
and for brick or masonry a foot thick
is ample. Puddled clay should be two
or three feet thick, or more near the
! bottom if the dam is a high one.
A dam should be not less than three
or four feet higher than the highest
possible high water mark, with a
! thickness at that point of twelve or
| fourteen feet, and should be wide
enough on top for a wagon road. The
| top soil where the dam is to be con-
structed should be removed to the
| depth of at least a foot, as water will
sometimes find its way between the
| bottom of the embankment and the
natural soil, and there is more or less
! brush, roots and turf on the surface
/ Wnlcn S0OulQ De removed
These are only a few salient consid-
! erations in relation to the subject;
! there are many details which are i'm
portant that cannot he touched upon
! in newspaper article for want of
space The proper thing to do in case
| a reservoir is contemplated of any con-
siderable magnitude, is to employ an
experienced engineer, who can calcu-
! late the area whose drainage will flow
| into the reservoir, the amount of rain
! fall and consequently the size of the
! dam and its waste weir, and so avoid
possible ruin or disaster in the future.
| Reservoir dams Of masonry, timber
or steel are of much interest, in the
building the first Of which the English
government has expended many mil
! lions of dollars in India; but each of
these forms is worthy a notice by it
self. A survey has been made for a
reservoir in Tonic Basin, Arizona,
which will be twenty-three miles long,
nine miles wide, and have an average
depth of ninety feet. The dam, be-
tween rocky cliffs, will be only 43O feet
long by 100 feet high. of solid cement
! laid masonry, and its estimated cost
| will be S1,500,OGO.
]. H. MARTTNEAU.