NAVFAC Specification TS-20312 (Maintenance of Wooden Utility
Poles) is a specification for groundline treatment and should be used as
a guide for developing a contract specification.
4.3 Internal Void Treatment. Liquid preservatives or fumigants
may be used to control decay and insect attack within the central core of
poles. These treatments require drilling holes into the decayed areas
and placing the preservatives or fumigants in the holes. The holes are
plugged following treatment.
Internal void treatment with liquids is most successful on cedar and
other woods that develop well defined rot pockets and where the transi-
tion from rotten to sound wood is abrupt; they are least effective in
Douglas-fir with poorly defined rot pockets. For Douglas-fir, use a
fumigant alone or in combination with a water-soluble preservative solu-
tion. To arrest internal decay, water-soluble chemicals, e.g. arsenicals,
fluorides or borates are forced into the voids and diffused through the
wet wood. Ants in pole voids can be controlled by injection with volatile
liquids combined with preservatives such as creosote or pen-
Serviceable poles with voids, hollows or insect galleries can be internally
treated with a liquid pesticide registered by the EPA for such use. Poles
shall be bored with a 3/8 inch drill bit, a sufficient number of times to as-
sure uniform internal coverage. Preservatives are pumped into the bot-
tom hole until it runs out the next higher hole. The hole is then plugged
with a preservative-treated plug, and preservative is then pumped into
the next higher hole until it runs out the hole above. This procedure is
repeated until the entire cavity is flooded or a maximum of one gallon of
preservative is used. Preservative pastes also can be injected into holes
to treat internal voids.
4.4 Fumigant Treatment.