The gazette-times. [volume] (Heppner, Or.) 1912-1925, 1915-01-07

E6l0OW long will it last?" is a
question asked perhaps
- more than any other O n
corning the use of wood pipe for ir-
rigation. That the life of such wood
pipe should be at least 20 years if the
pipes are fully exposed and support
ed free from all contact with the
soil; if the material is either fir or
redwood; and if the pipe has been
properly maintained, is the conclu-
sion Of a specialist of the United
States Department of Agriculture in
a professional paper on Wood Pipe
for Conveying Water for Irrigation
bulletin No. 1861. Irrigation en-
gineers and the owners of irrigation
works will be particularly interested
in this new pamphlet, which may be
had free of charge by applying to the
Department of Agriculture, Wash
ington, D. c.
Many millions of dollars are al
ready invested in wood pipe lines in
the United States and this amount is
being increased annually. Protection
of these investments demands that
existing pipe lines be maintained and
operated in accordance with what
experience has shown to be the best
practice. Future investments should
also be ~safeguarded by designing,
maintaining and locating new pipe
lines according to the best known
practices.
Life Short for Buried Pipes.
The length of life of wood pipe is
dependent OF the life Of the wood
rather than on the life of the bands,
although contrary theories were held
80 years ago. Only in rare instances
have the bands failed first. Corro-
sion Of the bands being a chemical
action, requires the presence of mois-
ture and oxygen. 1t usually occurs
most rapidly where pipes are buried
and the backfill is wet, under condi-
tions which, as a rule, are most ia
vorable for the life of the wood. Cor
rosion is greatly accelerated by the
presence of alkali in the soil.
The decay of wood pipe Is due pri-
marily to the growth of fungi, though
possibly certain forms of bacteria
may assist in the final destruction of
the wood cells. The growth of fungi
to an extent detrimental to the life
of the wood requires a favorable
combination Of moisture, air and
heat. The exclusion of any one of
these beyond certain limits iphibits
their growth.
Exclude Air.
n fn11nUC fhat with ninn1 h1rin6
in the ground the wood will endure
longest where the air is most nearly
excluded either by a high internal
pressure which completely saturates
1t or by a deep covering of very fine
soil.
In accordance with the foregoing
statement experience shows that in
contact with the soil wood pipe de-
Gays more rapidly under a light head
than it does under heavy pressure,
and other things being equal, it usu-
ally decays more rapidly in a porous
open soil, such as sand or gravel,
than 1t does In a fine soil of silt or
clay, because the finer soil is more
effective in excluding the air.
Experience appears to indicate also
that wood decays more rapidly in a
loamy soil, rich in humus or par
TALLY decayed organic matter than it
does in one containing little or none.
This is probably due to the fact that
the presence Of organic matter af-
fords favorable conditions for
the development Of fungus growths
and bacteria.
Fungi Cause of Decay.
Pipes fully exposed to the atmos-
phere and free from contact with
the soil will, as a rule, be too dry on
the exterior to favor the develop
ment of fungus spores, and so long as
the outside of a pipe remains dry nc
appreciate decay will occur, ever
though the internal pressure is very
light. Decay Of exposed pipes al
most invariably starts at the ends OF
slaves, as a result of leaky joints,
Where water leaks out and runs
down owe the outside Of the pipe
favorable conditions are afforded for