The full length of new wood utility poles is treated with preservatives before they are installed. After a number of years in service however they can become prone to fungal attack at the groundline and can require remedial treatment in the field.
The preservatives that are used to extend the poles life can be an environmental burden if they leach out of the wood into the water or soil. Powertech is studying several remedial treatments for wood poles, particularly those located in environmentally sensitive areas (such as near bodies of water).
Boron Rods
Boron compounds are effective wood preservatives that have very low mammalian toxicity, making them attractive for use on utility poles.However, they tend to leach rapidly and are highly water-soluble.
The insertion of solid (fused) boron rods provides a much slower chemical release and longer protection from fungal attack. Powertech has evaluated the use of boron rods in a five-year study.The results have lead to approval of their use in environmentally sensitive areas by the B.C. Ministry of Environment.B.C. Hydro has been employing the technology for the past two years. Boron rods are also useful for protecting pole tops after they are shortened, as happens when distribution power lines are lowered.
Pole Butt Encapsulation
One option to minimize the movement of the preservative from the decayed wood into the surrounded soil is to encapsulate the butt of the pole.This may also reduce the need for further remedial treatment.Powertech is performing field investigations and accelerated weathering of butt-encapsulated posts and poles.
Cost/Benefit Analysis
A software program is available from Powertech to calculate the cost/benefit ratio for remedial treatment of poles in different scenarios.The potential savings from undertaking remedial treatment can be calculated by taking into account factors such as the cost of replacing the pole (purchase and installation), the expected life of the pole, routine maintenance costs, and inflation.
Amount of Leachate
Utilities need to know the quantity of leachate that is entering the environment from their wood poles, particularly in pole storage yards. Powertech has studied this problem, ad has investigated methods of monitoring excessive surface chemicals on poles and ways of reducing leachates.