Powerco’s pole reinforcement trial in Whanganui
A pole reinforcement trial has been completed in Whanganui with the aim of extending the working life of wooden poles across Powerco’s North Island network.
Australian company, Logsys, has strengthened 200 poles with steel trusses and strappings and demonstrated the process to Powerco personnel recently, Asset engineer poles and towers, Andrew Jarman said.
“We still have 36,000 wooden poles in use across or network and many are still in good condition,” he said.
Sections of the Whanganui network were chosen as trial sites because of the high population of wooden poles there. Reinforcing criteria included the results of resonance (Vonaq) testing and the data gathered from pole top photography and LiDAR (Light Detection and Range technology) last year.
“Only poles that were likely to have another 20 years of life were chosen. The cost of reinforcing is between $1200-1300 per pole as opposed to $4000-7000 for a new concrete pole.”
The work involved placing a truss against each pole and ramming it into position with a pneumatic ram.
“The ram is powered by a trailer-mounted air compressor with an 80m hose reach, hence the need for 4WD access.”
Reinforcing poles was not new but the current method was.
“In the past the trusses have been bolted to the pole. But as soon as you drill bolt holes through the treatment zones of a pole you introduce microbes that leads to internal rot. The new method, developed in the United States, uses band strapping to hold the trusses firmly in place.”
Once the reinforcing was complete a certification label was attached showing the type of truss used, the date it was installed and other engineering data.
“ That information is also recorded in our GIS system so we have all the latest data at our fingertips.”
Asset renewals comprised a large part of Powerco’s annual CPP delivery programme.
“There are 265,00 poles on our network of which 36,000 are wooden. While it’s not practical to replace all of the wooden poles with concrete, the reinforcing is a good option to buy some time,” he said.
The Assets team would now study the data with a view to adopting the system.