Long experience and thorough study have established that it is prudent management and good stewardship for a utility to establish a pole maintenance program. Regularly scheduled inspections and judicious preservative retreatment increase system reliability, prolong the life of capital assets, reduce risk exposure to the general public, conserve natural resources, and enhance the safety environment for utility workers. Poles falling below code strength requirements can be identified, repair or replacement can be scheduled efficiently, and unnecessary replacements based upon age or appearance alone can be avoided.
Quality Pole Inspection and Maintenance Company is committed to providing the most reliable and cost-effective maintenance services possible, to protecting the pole owner’s best interests, and to providing the information which will assist the owner in selecting the maintenance interventions most appropriate for the individual system.
Inspection Methodology for In-Service Wood Poles
The pole owner may select from several approaches, and may opt to combines two or more as deemed appropriate.
Visual Inspection from Ground Level Designed to locate those readily visible defects which can be seen at a distance with the naked eye while standing at the base of the structure. This method can give valuable information about pole top conditions and can help to build a data base for scheduling future maintenance interventions. Little or no information is provided as to the wood strength or the presence of internal or below-grade problems.
Sound and Bore The inspector vigorously “sounds” the pole with a hammer from the groundline to as high as can be reached while standing on the ground. One or more borings are taken at the ground line; additional drilling can be specified for those areas which yielded suspicious sounding results. The drill shavings are examined for indications of decay. The holes are probed with a shell thickness indicator, voids are measured, and the holes are plugged with tight-fitting treated-wood or plastic dowels. This is the industry standard method of inspecting those poles set in concrete or which for other reasons may be impossible to excavate. Sound-and-bore inspections without excavation have historically been shown to miss as many as 50% of the poles whose below-ground deterioration have reached code replacement levels. More in areas with a low water table.
Visual, Partial Excavation, Sound & Bore, plus Supplemental Treatment Designed to gain information about the part of the pole where the decay hazard is the highest – the below grade portion – while minimizing the up-front maintenance cost. Designated poles, typically with ten or more years of service life, are visually checked. Then an excavation the width of the shovel is made adjacent to the largest seasoning check, usually to a depth of 18”. The pole is bored in the exposed area and probed to determine the integrity of the wood inside. It is always important to apply external preservative paste to any below-grade portion of the pole which has been excavated, as the digging has been shown to accelerate biodeterioration. The significant drawback is that much decay and some bad poles will be missed during the inspection process, and there will be no reliable extension of pole service life from adequate retreatment. In order to meet code strength requirements, this type of inspection must be repeated on a 3-5 year interval.
Visual, Excavation, Sound & Bore, plus Supplemental Treatment This is the most endorsed maintenance intervention for pole owners in the southern US. Poles are excavated to a depth of 18”. All the steps described in the Visual and Sound and Bore section are applied. The outside below-grade portion (the “shell”) is tested with a check scraper or similar tool. All outside rot is removed. Measurements are taken to determine the remaining effective circumference, including appropriate deductions for internal voids. Full groundline inspections have historically been credited with identifying 98-99% of the in-place poles currently falling below code strength requirements. The full groundline maintenance approach can be repeated on 8-12 year cycles, depending upon the decay hazard zone; data of millions of poles confirms that this method is about 98% successful in keeping wood poles serviceable. Most utilities find that such service-life extension more than offsets the costs of inspection.