Conserving energy by environmentally acceptable practices in maintaining and procuring transmission poles for long service ; October 1996

The Cooperative continues to actively\ud address a diverse array of issues related to\ud the effective use of wood utility poles.\ud The trials to evaluate the effectiveness of\ud MITC-Fume are now in their seventh year\ud and continue to show that methylisothiocyanate\ud (MITC) levels in MITC-Fume\ud treatments remain higher than comparable\ud metham sodium treatments. The levels of\ud chemical are, however, declining, suggesting\ud that this treatment may need replenishment\ud in 3 to 5 years. Trials with the solid wood\ud fumigant Basamid continue to show that\ud MITC release can be enhanced by addition of\ud small amounts of copper. Field trials\ud suggest that these additives become less\ud important with time. As a result, unamended\ud Basamid may be suitable for\ud treatment where the risk of immediate\ud decay is not high, but the utility wishes to\ud protect against future attack.\ud Field trials with various water-diffusible\ud internal treatments continue to show that\ud these treatments move more slowly through\ud Douglas-fir heartwood than do fumigants.\ud Boron levels in pole sections treated with\ud fused borate rods remain at levels that will\ud protect against fungal attack 6 years after\ud treatment. Similar trials with a boron/\ud fluoride rod indicate that neither fluoride or\ud boron levels in the poles are adequate for\ud wood protection 2 years after treatment.\ud While the dosages tested were relatively\ud low, the volumes of chemical were similar to\ud the liquid volumes normally applied during\ud internal remedial treatment. We will sample\ud these poles next year to ensure that our\ud measurements accurately reflect the\ud chemical levels present.\ud Trials to evaluate the effects of glycol on\ud boron movement from fused borate rods\ud suggest that glycol enhanced boron diffusion\ud to only a slight extent. This effect was most\ud pronounced at lower moisture contents.\ud This trial was established to identify\ud methods for improving boron movement in\ud drier wood. In addition, moisture measurements\ud in these poles suggest the internal\ud wood moisture content varies widely both\ud seasonally and positionally. While elevated\ud moisture levels can negatively affect the\ud movement of gaseous fumigants, excess\ud moisture is critical for diffusion of boron or\ud fluoride and its absence around the\ud treatment site can markedly reduce the\ud efficacy of rod treatments. These poles will\ud continue to be monitored to assess both\ud boron movement and seasonal changes in\ud moisture content.\ud Trials to identify safe, effective and easily\ud used systems for protecting wood exposed\ud during field fabrication are continuing.\ud Boron and fluoride continue to provide\ud excellent protection to field drilled bolt holes.\ud These treatments are safe and easy to\ud apply, and have provided protection in our\ud field test for 14 years. Trials of similar\ud formulations on simulated decking are also\ud reported to provide additional information on\ud the ability of boron and fluoride to protect\ud exposed Douglas-fir heartwood.\ud Efforts to improve the effectiveness of\ud through boring as a method for enhancing\ud the treatment of Douglas-fir poles are\ud continuing. This past year, we evaluated\ud preservative distribution around through\ud bored holes as a means of developing\ud optimum through boring patterns that\ud maximized treatment while minimizing\ud potential strength effects. These trials\ud suggest the diamond shaped through boring\ud zone of effect is relatively narrow. This\ud information will be used in the coming year\ud to construct optimum patterns for poles of\ud various classes. The goal of this project is\ud to develop a standard through boring\ud pattern that would permit automation of the\ud process. This would create the potential for\ud cost savings on new poles.\ud Trials to evaluate the durability of\ud western redcedar are nearly complete.\ud These trials were initiated because of\ud concerns that second growth western\ud redcedar might be less durable than poles\ud cut from older trees. As expected, cedar\ud varied widely in its resistance to fungal\ud attack. This resistance, however, was not\ud related to tree age, suggesting that there\ud might not be a difference between so-called\ud "old-growth" and "second growth" material.\ud These data will be more thoroughly analyzed\ud once the final set of trials are completed. In\ud addition, we are evaluating more rapid\ud methods for assessing cedar durability by\ud measuring tropolone content. Tropolones\ud are an important component of the\ud extractives that make cedar heartwood so\ud durable.\ud Field trials of various externally applied\ud supplemental groundline treatments are\ud continuing at sites in Oregon, California, and\ud New York. Trials in Corvallis, Oregon, have\ud shown that various copper naphthenate,\ud fluoride or boron based systems are at least\ud as effective as the pentachlorophenol\ud (penta) based systems that were formerly\ud used for this purpose. Penta concentrations\ud in one system have now declined below a\ud protective level, while the copper based\ud systems continue to remain at a protective\ud level. Field trials in California are following\ud similar trends and indicate that the\ud alternative systems will provide comparable\ud performance.\ud Fungus cellar trials of copper\ud naphthenate treated western redcedar\ud stakes continue to show that this chemical\ud provides excellent protection to cedar\ud sapwood. Weathered wood that was\ud treated with copper naphthenate continues\ud to perform more poorly than freshly sawn\ud wood treated to similar retention levels.\ud Variations in permeability likely account for\ud these differences.\ud A new Wood Pole Maintenance Manual\ud has been completed and is now ready for\ud distribution. This update of the 1979\ud publication includes more information on\ud initial pole procurement and closely follows\ud the video by the same name that we\ud produced in 1994