The Bismarck tribune. [volume] (Bismarck, N.D.) 1916-current, 1929-10-17

problem is much nearer a place where
they must attend to it than their va
ter supply problem.
There arc three complete sewage
disposal plants in the state. One is
at Minot and two at jamestown. n
OF which is for the State hospital.
All these plants had trouble this sum-
mer. One Of the primary reasons
was because Of insufficient diluting
water in the stream. The Minot plant
on September 10 was discharging SO
c. I. S. into the stream whose flow
above the plant was only 0.6 c. f. S.
The two jamestown plants on Sep
TENDER IL were discharging 0.6 c. T. S.
into the stream and were being mixed
with 90 c. I. S. of river water which
is IL dilutions. Yet it was far from
satisfactory, although not SO filthy as
the Mouse river below Minot. Heavy
chlorination is the only solution UNI
less stored water is available.
The minimum flow of the Mis-
souri, river at Bismarck this sum
mer was measured and found to be
10000 c. +. S. or enough water theo-
retically to dispose of the raw seW-
age from about two million people.
The Chicago drainage canal is TO-
carrying that amount. as l recall it.
There. incidentally. is a classic illus
tration of where disposal by dilution
has failed. It was originally designed
on tho basis of 3.3 cubic feet per Sec
ond per 1000. but the excessive indus
trial wastes have entirely over-taxed
it. The val department is now forc-
ing Chicago to partial treatment.
I'VE have an acute problem OF
that nature arising at West Fargo.
The packing plant and creamery
wastes from the Armour company'S
plant are making an open sewer Of the
Sheycnne river. This together with
Fargo's sewage puts a heavy load. I
am told. on the filtration plant at
Grand Forks.
Stored Waters
when an u%nregulated river supply
approaches exhaustion the next step
is storage of the surplus run-off. To
have a stable perennial lake or reser-
voir four factors must be in cquilib-
rum. The inflow from the water
shed plus the rainfall onto the lakes
surface must equal the evaporation
from off the lakes surface plus the
outflow. Deep p%ercolation is assumed
to be negligible.
Mos OF natural lakes and res
ervOir sites are not SO favorably To-
Gated. Devils Lake has about 18 inches
Of rain contributed to its surface
annually. but it loses, say. 81 inches
in evaporation. Then the net annual
loss Is Is inches, but the net annual
fall In the water surface has been
only 5 inches over a 26-year period.
Then the difference, or 8 inches Of
water over its area, must come from
the contributing watershed.
"On a natural lake which Is SO sit
uated that evaporation exceeds on
tributionS of inflow and rain to any
extent, the only absolute solution is to
annex more watershed If possible. A
dam will only stave off the evil day.
and make the times when the lake
goes dry farther apart.
THE upper DeS Laos at Kenmarc is
an illustration. It has steep sides, SO
its surface area does not greatly
change. Watershed inflow contributes
over . long period Of years about 10
inches over the area Of the lake; rain
fall adds Is inches. making a total
average annual addition of Is inches.
Evaporation may be assumed to be 81
inches and outflow about 3 inches,
making q total average annual loss
Of - inches, or a net annual loss Of
3 inches from the water surface. Over
. long term Of years the maximum
water depth Is about 100 inches. then
the lake should 60 dry or get very low
on m average Of nee every II years
or 20. 100 divided by 8.
But II . dam were constructed to
save and store most Of the 3 inches Of
outflow the loss would be mainly
evaporation. Then the net loss would
amount to, say. 5 inches a year. The
lake would then 60 dry. or nearly SO,
on IN average Of once In only about