The Mankato free press. [volume] (Mankato, Blue Earth County, Minn.) 1879-1924, 1908-09-11

Mankato, MINI. Sept. 4, 1905
DR.. j. w. Andrews, Mayor. Man
kato, MINI. Dear Sir: Since SUBJ
uniting the last report to you, I
have devoted the greater part of
my time to the water system,
giving special attention to the
wells and suction mains. In test
ing the suction mains a bad leak
is evident somewhere between Sec
ond and Broad streets. This part
of the suction main has now been
disconnected and that portion be-
tween Second street and the pump
ing station seems to be in good
condition. The suction mains seem
to be composed of various mater
: lals, some steel pipe, some wrought
iron and the remainder cast iron.
The cast iron pipe is of the bell
and spigot joint. The first requis-
lite of good suction main is that
is shall be absolutely air tight.
This is accomplished much easier
with a Hanged joint than with the
bell and spigot joint. Another re-
quisite; it must be constructed of
durable material, for which reason
wrought iron and steel pipe should
not be used, the durability of cast
iron being much greater. All con-
nections in suction main should
be carefully made with long, round
ed elbows of Y'S, sharp ct" con-
nections cause too much loss Of
head by friction. Lasting, the
grade should be upward toward the
pump and not downward.
Requirements Disregarded.
In looking over your suction
mains I find that all these require
ments have been disregarded. And
without single exception, the
grade of the suction mains are in
the wrong direction, and most of
the connections ct"
This faulty construction, in addi-
ton to causing a great deal of
unnecessary friction, requires that
the pumps work under a small
back pressure instead of drawing
on the wells, thus reducing the
available supply very much.
The old we'll at the pumping
station and the Broad street well
are in such condition that no test:
could be made of either; but from
the other wells the following re.
suits were secured:
The new we'll at the pumping
station, the Second street we'll and
the two wells at the gas works,
together give static pressure of
ten pounds, and flow of $40
gallons minute. The Second
street well has a static pressure of
seven pounds and a flow of two
hundred gallons a minute. The
two wells at the gas works show a
static pressure of nine pounds and
a combined flow of 1896 gallons per
minute. The pressure of the later
taken at the gas works is twelve
pounds. The main from the gas
works is but six-inch. This with
the above flow will give loss of
head of seventeen pounds due to
friction alone. Had the pipe been
ten-inch instead of six.inch the
flow would be easily 600 gallons
per minute.
Faulty Connection Shown.
You will also note that the
combined flow is las gallons per
minute less than the sum of the
flows of the several wells taken Sc
parately, which shows very nicely
the result of the faulty connection
in reducing the flow.
In this connection it is also in
teresting to note the decrease in
pressure from what it was a few
years ago. The new we'll has fall
len from fourteen pounds to ten
pounds, the wells at the gas house
from eighteen to twelve, being in
each case very nearly one-third of
the original pressure. The deep
well at Highland park, in which
. thirty years ago the water stood
within seventy feet of the sur
face, now stands at two hundred
and ten feet from the surface.
All of which goes to show that
Mankato is drawing on the artesian
supply faster than it is being re-
plenished, and it is now high time
to economic.
am submitting map of the
central portion of your city, show
ing the general location of the
artesian wells now in use and also
two proposed locations for a new
well, and location which I take
the liberty of suggesting as I
think it preferable to either of
the proposed locations. From the
data which I have collected, it
seems quite evident that the rad
Jus of influence, or the distance
around the we'll where the natural
pressure is affected, is over one
thousand feet, which means that
two wells, so placed so as not to
interfere with each other, must be
at least half-mile apart. And
you will notice by the map that
almost all of your wells are en-
closed within a radius of that
length.
Another thing which should be
considered is that the ground flow
seems to be from the south and
west. Therefore, I should say
that the location of new well at
either of, the proposed locations is
not desirable, not only from the
fact that they are too close to.
TCortfpyyoA ~ Dour~ Ue~r,~