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 TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
and must be approved for use. None of the preser-
This tool has a sleeve-like hammer; and, through
vibrations carried to the hand, it is possible to de-
vative should be exposed when backfilling is com-
tect decay below the ground line.
pleted. Personnel applying pesticides must be certi-
c. Sounding. Make a sound test to check for inter-
fied in accordance with applicable directives.
nal decay.
(3) Backfilling. R e p 1 ace with sufficient resteril-
d. Nondestructive pole testing. The Electric
ized soil tamped to avoid any water-collecting de-
Power Research Institute (EPRI) has developed a
pressions.
"PoleTestTM" instrument that analyzes the sonic
f. Internal inspection. One or two borings should
waves it sends through the pole to indicate the
be taken above or below the ground line when
strength of the pole keyed to its wood species and
sounding or other inspection methods cause a doubt
diameter.
as to the sturdiness of the interior pole condition.
(1) Components. The complete testing setup
g. Accuracy. When a reasonable accurate deter-
consists of a programmed dedicated instrument, an
mination as to the condition of poles cannot be made
input sensor, a pendulum impactor, output sensor,
by spot inspection methods, the more thorough pro-
and impact nail. Specialized tools are provided to
cedures described for the pole-by-pole inspection
install pole-mounted items.
should be followed. For these cases, the excavated
(2) Operation. The operator designates the
poles should be groundline treated and so recorded.
wood species, diameter and length of the pole. After
4-15. Wood pole-by-pole inspection proce-
the correct input sequence and pendulum impacts,
dure.
the unit will display the pole fiber strength, diam-
eter, and species. From this information, the con-
Before any extensive inspection or maintenance
formance of the pole's strength to NESC require-
work is begun, it should be known or ascertained
ments can be determined by comparison with the
that the line (or individual pole) can be expected to
required maximum fiber stresses for the various
remain in the same position for several years with-
classes of poles given in ANSI 05.1.
out relocation. Before proceeding with the inspec-
(3) Engineering judgement. Interpreting the re-
tion, the upper portion of the pole should be ob-
sults requires engineering judgement. Testing
served from the ground to make sure it has not been
should be made at the groundline unless there are
badly damaged by woodpeckers, lightning, or other
more critical stress locations, that is points of dam-
causes that would require replacement regardless of
age or points of line loading. Since the existing
the groundline condition. Nondestructive pole test-
bending strength of the pole determines whether
ing may be used where "PoleTest" equipment is
the pole has adequate strength, the orientation of
available. (See para 4-14.) Otherwise sounding and
sensors should normally be perpendicular to the
test boring may be necessary.
a. Sounding. If the pole condition appears good,
direction of the line.
e. Groundline inspection. If the soil is soft
then the pole should be sounded. This is a method of
enough, probing through the soil at two or three
checking for interior decay above the ground line. It
places several inches (centimeters) below the
is not an infallible test and requires considerable
ground line may reveal sound or decayed wood
practice to attune the ear to meaningful sounds. It
without excavation. Excavation should remove soil
should not be relied upon until considerable experi-
only where one or two major ground level separa-
ence has been acquired.
tions (checks) are present in a pole.
(1) Method. With a l- or 2-pound (0.5 to
(1) Excavation. Soil may be removed to a depth
l-kilogram) hammer, strike the pole squarely and
of 8 to 12 inches (20 to 30 centimeters) and the
firmly all around the pole from the ground line to as
below-ground pole surface examined or probed.
high as can be conveniently reached, while listening
to the sound. A good pole has a solid ring, whereas
(2) Soil sterilization. Excavation aerates the
one containing decay may give a hollow sound or
soil and encourages the growth of fungi. When new
dull thud. Often, however, such things as checks,
pressure-treated poles are first installed, some of
separations, shakes (separation along the grain of
the preservative diffuses into and sterilizes the soil
the wood, usually occurring between the annual
immediately adjacent to the pole. When the soil
rings due to causes other than drying), loose slivers,
around the pole is disturbed for any reason, or the
loose molding, guys, load carried, wood density,
pole is relocated, the soil must be sterilized. Use 2
moisture content, and the pole loading will affect or
or 3 gallons (8 to 12 liters) of an approved preserva-
alter the resonance.
tive solution and thoroughly mix with the backfill.
(2) Purpose. This method avoids needless exca-
Many effective pesticides that are easily applied in
most soils prevent subterranean termite attack; kill
vation of poles found badly decayed internally above
fungi and weeds in the treated area; are very toxic;
ground and assists in detecting the most likely
4-7
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