Feb. 21, 2005 — The year 2003 could be remembered as the year the world went dark. The great New England blackout and the countrywide outage in Italy taught us all the costly nature of grid failures. It also showed how easily we take a reliable, uninterrupted flow of power for granted. While exact causes may never be universally agreed upon, many theories suggest that tree branches tangling with transmission lines could have played a major role in triggering these outages.
Vegetation management, as most utility managers know, can be a monster of a challenge to deal with. When mechanical vegetation control methods are used extensively, the costs of employing contracted workers and the risks of machine-operator injuries are great. Brad Weidenfeller, transmission line coordinator for Xcel Energy, Northern States region, must grapple with these safety and budget challenges every day.
“In order to reduce the need for mechanical trimming and cutting, we employ a carefully chosen line-up of herbicides, including low-volume herbicides, wherever possible to help keep our expenses and resources in check,” Weidenfeller says.
Mechanical controls – widely used but wildly expensive
Weidenfeller and his Monticello, Minn.-based vegetation management team oversee 7,000 miles of transmission lines in Xcel Energy’s Northern States region. These lines are spread throughout Minnesota, Wisconsin, North Dakota, South Dakota and Michigan. This totals approximately 85,000 acres of land, including 25 million square feet of substation bare ground.
In the past, the Northern States region managed its ROWs using a “hot spot” approach – mechanically trimming trees only when they were close to causing a problem, rather than using more proactive strategies. Hot spotting sometimes led to projects going over-budget – Xcel was eventually required to spend far more per mile than in previous cycles.
This emergency-style strategy costs more maintenance time per ROW mile. Costs are higher when crews need to be hired and deployed on short notice, whereas proactive maintenance and planned crew deployment can control costs. Additionally, there were a greater number of complaints from customers when the utility had to exercise easement rights and repeatedly cut limbs from trees that were planted too close to the lines.
Although recent advances in tree-trimming machinery and equipment have provided crews with bigger and more powerful tools that can work faster, more
efficiently and less intrusively, any increase in human interaction with heavy machinery and power lines will naturally increase the chance of accidents and injury.
Low-volume herbicides improve ROW management
Citing the need to reduce costs, increase vegetation control and improve safety, Weidenfeller decided to replace many of his mechanical control methods with a new low-volume herbicide strategy. When determining application rates and timing, Weidenfeller worked closely with BASF vegetation management sales specialist, Randy Lusher for technical advice. Carefully considering the area’s climate, vegetation and Xcel’s budget, Lusher based his recommendations on how Weidenfeller could cost-effectively achieve the best vegetation control.
For the utility’s cut stubble, cut stump and foliar herbicide application projects, Weidenfeller contracts with Wright Tree Service, to apply Arsenal® herbicide from BASF throughout the year.
“Arsenal is our primary workhorse,” Weidenfeller says. “It provides good control of oaks and takes care of stumps without the need to go back and mechanically dig them up or break them apart.”
From May to October, Weidenfeller uses a mixture of 6 oz. Arsenal,1.0 qt. picloram and 1.0 oz. Escort per acre for foliar and 6.0 oz. Arsenal with 1.0 qt. picloram for cut stubble treatments. For cut stump treatments performed throughout the year, he uses a mixture of 4 percent Stalker® herbicide, 33 percent BK800 and 63 percent Bark Oil Blue as a diluent1.
Weidenfeller also uses additional BASF products to complete his varied integrated vegetation management (IVM) projects. He has been using Sahara® herbicide at 8 lbs/acre to completely clear substations of vegetation. Weidenfeller has also begun using Plateau® herbicide for suppression of weedy grasses, reducing the need for mowing and ensuring long-term weed control.
To date, Xcel Energy has placed 100 percent of the high voltage right-of-ways (ROWs) on regular IVM cycles. The lower voltage ROWs – those that are 115KV down to 23KV – are nearing 100 percent inclusion in the IVM cycle.
Preventing power outages without budget outages
Weidenfeller anticipates that long-term vegetation management cost savings for Xcel will be substantial. In addition, since putting a larger focus on low-volume herbicides, Weidenfeller has noticed a downward trend in tree-related Xcel customer energy interruptions. While 1998 had over 30,000 energy interruptions, every year between 1999 and 2002 had well under 20,000 interruptions.
Weidenfeller has also experienced dramatic cost savings using these herbicides. “The machinery and all the work hours that piled up using mostly mechanical methods were expensive,” Weidenfeller said. “For example, a 33-mile ROW line that we aggressively reclaimed back in 1999 cost $116,000 to clear using a mechanical-only strategy. On that same line we have $85,000 budgeted for 2003 – this includes the herbicide, the applicator crews and the mechanical methods we still use. Even better, I think we’ll end up using only $45,000 of that budget to get the high level of control we need – that’s a savings of $71,000 compared to what we did in 1999.
“Eliminating or reducing many of our mechanical methods in favor of herbicide controls,” he says, “has allowed us to maintain the same amount of ROW miles with better results at greatly reduced expense.”
By including low-volume herbicides in its IVM program, Weidenfeller was able to deploy two- or three-man teams instead of the usual four or five, greatly reducing contractor expenses. With less reliance on heavy equipment and machinery, the potential for work crew accidents is diminished. Herbicide applications also reduce the need to tear up topsoil surrounding problem trees, making ROW vegetation management far less disruptive to nearby landowners.
“Anything we can do to help prevent conflicts between the utility and private property owners makes life easier for everyone in the community,” Weidenfeller says. “Once they recognize that the utility won’t have to make as many visits to their properties for tree trimming, they are pleased with the solution.”
To learn more about BASF Vegetation Management, Arsenal, Stalker, Plateau and Sahara, visit www.vmanswers.com.
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