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 The hole should not be through the pole or intersect seasoning checks
which would allow the fumigant to escape. To assure good distribution of
the fumigant, holes are spaced evenly (and drilled in a downward direction)
around the pole in an upward spiral pattern with a vertical spacing of 6 to
12 inches. If more than two treating holes intersect an internalvoid or decay
pocket, re-drill the holes further up the pole into relatively solid wood
where the fumigant will gradually volatilize and move through the wood.
The fumigant placed in decay pockets will be lost if the seasoning checks
connect the pocket to the outside of the pole. If the decay pocket is above
the ground line, holes should be bored above and below the pocket. A three
inch long treated plug is inserted into each hole after treatment.
Fumigant applicators must wear protective clothing and stand upwind from
the point of application. The proper amount of the chemical is applied to
the lowest hole first, leaving enough space for the plug. A tight fitting
preservative treated plug is driven into the hole. Care must be exercised
to avoid squirting the fumigant from the hole while driving the plugs. The
applicator should continue to work up the pole one hole at a time.
Decay fungi recolonize vapam-treated poles in about five years, but the
fungal population remains low for at least nine years. These poles should
be retreated every nine years by placing additional fumigant in the same
hole.
The effectiveness of wood fumigants for long term insect control is uncer-
tain. Vapam may control subterranean termites, however, carpenter ants
are known to reinfest wood shortly after fumigant application, perhaps
because of the decreased fumigant concentration.
NAVFAC Specification TS-20312 provides additional guidance on pole
fumigation requirements. Application of wood preservatives requires
DOD or State certification (See Section 1.2).
1.4.4 Inspection & Maintenance Procedures (Boom-Boards).
1.4.4.1 Problems to Be Found.
Nature of Timbers. Timbers are different than poles in that they are sawed
products. With the exception of Southern pine, they usually do not contain
a continuous sapwood band which is easily treated. Therefore incising of
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