Over the past couple of months, I have traveled many miles in doing work for a transmission utility client. While doing so, as I traveled between transmission sampling locations and, of course, passed by a lot of roadside distribution line.
I couldn’t help but notice work, or lack thereof, on distribution lines. I noticed recently herbicide-treated spans that stopped abruptly, only to resume somewhat further along. At first, I assumed this difference was due to landowner refusal. However, as my casual observations continued, I found too many cases where herbicide application stopped without a change in land ownership. Were these skips due to the fact that the brush was too tall, resulting in what the public might deem an eyesore along a heavily traveled road? As the observations accumulated, this speculation had to be dismissed, as there were numerous sites with similar height and density of brush that had been sprayed.
My curiosity having been piqued, I began to pay even more attention to the distribution system VM as I passed mile after mile. I observed spans that had been mowed that also abruptly stopped. Of course, I didn’t know what the height of the brush was that was mowed. However, where the mowing had ceased, there was very commonly heavy brush that was 3 to 6 feet below the conductor. The mowed area may have been two or more spans. The not-mowed spans typically were two to six. In none of these situations did I see evidence that would suggest a more stringent standard is being applied between the substation and the first protective device.
On meeting with my transmission client representatives I advised them that in all the miles of their system I had only encountered two things I wished to bring to their attention. They were already aware of both. I happened to comment that this was a strong counterpoint to what I had coincidentally observed on the distribution system during my travels. They inquired what I had seen. In relating the above observations and the fact that I had seen about a half a dozen locations that were being electrically trimmed, they smiled and nodded knowingly. They informed me that from their conversations with the distribution company they understood this to be a planned, just-in-time, reliability-centered maintenance program. Now these fellows I was conversing with have known me for a long time and they consider it good sport to incite a tirade from me. So they sat there with grins on their faces waiting for my derisive castigation of this so-called planned program.
First, I absolutely object to the perversion of perfectly good concepts such as reliability-centered maintenance to justify underfunding VM. Secondly, unless you can monitor your system in real time for tree to conductor clearances and hazard trees, the concept of just in time cannot reasonably be applied to utility VM.
We have an old term for the program this distribution company has. It’s a hot spotting program. What I observed will necessitate this utility to make repeated trips to the same area or feeder to do VM work. To think that by applying the terms reliability-centered maintenance and just in time to this program makes it cost-effective or prudent from a risk management perspective is simply delusional.
First, on the cost-effectiveness of a planned program vs. a hot spotting program: I quantified, presented on and wrote about this in 1989, and it was published in the Journal of Arboriculture in February of 1990. It was found that hot-spot pruning was 30% more expensive than a planned, cyclical program. Hot spot mowing, because the equipment cannot just travel down the road and needs to be trailered, must necessarily be even more expensive. Underfunding leads to hot spotting and consequently, such a program is delivering less per allocated dollar than a properly funded and planned program.
Secondly, as a professional, it is your duty to honestly assess how effectively your program addresses risks to the company and to inform your senior management of it. If senior management is focused on cutting costs at all costs, they might not like to hear the facts. Nonetheless, having stated the case, it’s then up to them to decide what level of risk they are willing to tolerate. As I have been, and increasingly am, involved in powerline-initiated wildfire litigation, you don’t want to be in the position where a tree on your system started a wildfire with damages in the hundreds of millions and you’re writhing over your choice to permit delusions about VM program efficacy to exist.
