The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1917-12-27


prepared by the United States Depart
ment of Agricultural
Farm reservoirs are rather difficult
to classify for the reason that they are
dependent on a number of unlike fac
tors. The materials used the methods
of construction, locality, cost, source
CT water supply, and purpose which
they are intended TO serve. all exert
more or less influence. Such being
the governing conditions, any attempt
to present types of such structures
cannot well be made without due con
sideration Of the most influential fac
tors. Thus an earthen reservoir
planned and built to store water for ir-
rigatiOn may be unsuitable to provide
water for stock. Similarly, the mate
rails and methods Of construction
which may he used for reservoir fed
by pumping plant may not be well
adapted to a reservoir located In the
bed of a stream. Furthermore, cost
which is justfiable in the citrus or
chards of southern California may be
prohlbitive in the Great Plains area.
Reservoirs Considered.
Reservoirs used with pumping plants
Will be considered in this article. The
following description is intended to be
typical of a large number of small
earthen reservoirs recently built in
central California to store water fur
nished by small pumping plants and
thus secure large and more effective
head for irrigation. The net capacities
of the reservoirs examined ranged from
one-fifth to seven acre-feet and the
average cost per acre-foot OF storage
capacity was $07.
The crops irrigated consisted of al
falfa. fruit trees, grapevines, nursery
stock and gardens.
This type of farm reservoir In reality
Is an adjunct to pumping plant and
the proper relationship between the
two should he studied carefully. The
main purpose of both is To secure at
the lowest rates. water from wells in
sufficient quantities for successful irri-
cation. This can be done by installing
n pumping plant of large enough ca
pacity and dispensing with the reser-
voir. This, however, would he likely
to entail Il greater first cost for equip
ment, higher annual rate for power,
and shorter operating time. Where
there Is no reservoir the capacity of
the pumping plant would have to be in
creased nj least go per cent and since
electric current often Is sold at fiat
rate per horsepower based on the
horsepower of the motor, IL follows
that pumping plant driven by ten
horsepower motor working ten hours
IA day would cost twice us much for
current as iive-horSepower motor
working twenty hours II day.
Rectangular in Form.
This type Of reservoir usually is rect
angular in form but II may he circular.
The former is more APT to conform to
fence lines, roads, fields. etc. is more
readily laid out and built, but the lat
ter requires less material and usually
presents n better appearance. Before
site Is selected il is well 10 find out
the nature Of the subsoil beneath II.
This may be done by boring hole with
nm auger or post-hole digger, or by dig
cling pit to the required depth. "
the examination shows the subs6ii 10
be porous to considerable DEPTHS, the
selection of another site may be advis-
able, but If the porous material Is con
fined to single stratum II often is
possible to lower the floor Of the reser-
voir to n more impervlous foundation
by excavatlng the upper stratum. Such
a course Is followed often for the pur-
pose Of reducing the cost. as the most
economical method of building an EN-
bankment around n reservoir Is to take
part of the material from within the
site.
The site should be cleared of all
brush, weeds or other matter subject
to decay, plowed and ridged and a
trench dug along the center line of the
embankment. One of the cheapest and
best methods Of pudding the material
placed In the trench as well as that In
the lower and central part of the en-
bankment, provided the material is
other than clay, Is TO fiji the trench
about two-thirds full of water and
dump good pudding material irto II.
The puddled center core should be car
ried mp into the emtankment for some
distance.
Typical Reservoir.
On farm near MADEIRA, Cal, there
Is a reservoir somewhat typical Of this
class. 1t Is about 30 feet square, the
banks are Z feet high with slopes Of Q
to l inside and ~ to l out
side, and the top width feet.
The reservoir covers acre of
land and has capacity of AZ
acre-feet. After the banks were
formed by means of fCur-horse Fresno