By Joel Roehl , BASF
Vegetation management, as most utility managers know, is a gargantuan challenge. When mechanical vegetation control methods are overused, the costs of employing contracted workers and the risks of machine-operator injuries are great. This is where low-volume and ultra low-volume herbicides can help.
Low-volume and ultra low-volume herbicide applications allow utility vegetation managers to control their right-of-way corridors (ROWs) while using lesser amounts of herbicide. These methods have many advantages. First, utilizing the lowest volume of herbicide is key to practicing environmental stewardship. Also, the techniques allow applicators to treat the target vegetation, without impacting surrounding desirable plants. As an added benefit, when applicators use less herbicide, they don’t have to spend as much time remixing and refilling herbicide containers.
Low-volume Herbicides at Work
“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,” said Brad Weidenfeller, transmission line coordinator for Xcel Energy, Northern States region.
Brad Weidenfeller, transmission line coordinator for Xcel Energy Northern States Region.
Weidenfeller and his Monticello, Minn.-based vegetation management team oversee 7,000 miles of transmission lines 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-only trimming trees when they were close to causing a problem, rather than using more proactive strategies. However, hot spotting sometimes led to projects going over-budget, and 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 lines.
Although recent advances in tree-trimming machinery and equipment have provided crews with bigger and more powerful tools, any increase in human interaction with heavy machinery and power lines will naturally increase the chance of accidents and injury.
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.
Together, they came up with the following ROW plan which Weidenfeller has put into practice:
- 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.
- 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 1 percent Stalker herbicide, 33 percent BK800 and 63 percent Bark Oil Blue as a diluent.
- 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 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 ROWs on regular IVM cycles. The lower-voltage ROWs-115 kV down to 23 kV-are nearing 100 percent inclusion in the IVM cycle.
Since putting a focus on low-volume herbicides, Weidenfeller has noticed a downward trend in tree-related energy interruptions. While 1998 had over 30,000 energy interruptions, every year between 1999 and 2002 had well under 20,000 interruptions.
Weidenfeller also experienced dramatic cost savings using these herbicides. “For example, a 33-mile ROW line that we aggressively reclaimed back in 1999 cost $116,000 to clear using a mechanical-only strategy,” Weidenfeller said. “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.”
ULV in Vegetation Management Programs
Arborchem Products Co. is an emerging leader in implementing the ultra low-volume (ULV) system. It is owned by the Asplundh Tree Expert Co. and acts as the distribution arm for herbicides. In addition, Arborchem distributes adjuvants, equipment and parts designed to help execute vegetation management programs.
The Phyto-bland formulation allows droplets to stay wet on the leaf longer, slowing evaporation and increasing saturation.
Asplundh applicators demonstrate and use the ULV technique with utility customers throughout the U.S. They’ve found that the ULV technique provides maximum control with minimal volume per acre-both goals for which many utilities aim.
Joe Lentz, manager and technical expert with Arborchem, trains both Asplundh personnel and Arborchem customers on proper ULV application, and, while many in the industry still use mechanical control in ROWs, they are starting to recognize the benefits provided by low-volume herbicides and highly targeted application methods.
The ULV technique uses a THINVERT Application System from Waldrum Specialties, which combines a special nozzle design and an oil-based fluid to distribute only the minimum amount of herbicide required for weed removal. The nozzles produce small uniform droplets that are more stable because of the fluid’s viscosity. A thin film of oil coats each droplet so it does not evaporate or break apart as easily on its way to the plant from the sprayer. Known as THINVERT RTU, the fluid contains less oil than typical oil-based carriers because it is combined with water.
Specifically, THINVERT RTU is a combination of Phyto-bland Paraffinic oil blended with emulsifiers, surfactant and water to make a thin invert emulsion. Once blended with the prescribed rate of herbicide, it is applied with the specially designed ULV nozzles.
“With a water-based material, a backpack nozzle typically applies about three pints of water per minute for effective coverage. The ultra low volume application using the THINVERT nozzle with the same type of pattern and coverage, requires only 10 ounces per minute for the same coverage and effectiveness,” said Lentz. The Phyto-bland formulation allows the droplets to stay wet on the leaf longer, slowing evaporation and increasing saturation. The herbicides do the rest.
Using the ULV technique, Asplundh successfully controlled vegetation in co-op and investor-owned utility ROW applications at rates varying from 1 to 5 gallons per acre. Their application methods included backpack, cut stubble, and broadcast using an ATV, or side trimming.
“This application system has allowed us to show people that herbicide applications can, and should, be part of a quality vegetation management program,” said Lentz. “When people see how we can target and control problem species, limit the impact on the desirable species growing on the ROW, manage the land for wildlife and do it all in a cost-effective program, they’re immediately interested.”
In the first stage of a new vegetation management program, it is often necessary to reclaim the ROW with a mechanical method. After one year of resprout on distribution (15 to 60 feet wide), a ULV broadcast application can enhance vegetation control in a cost-effective, low-profile manner. A ULV Widecast nozzle system is mounted on the back of an ATV or Argo. This Widecast application method allows utilities to put out 25- to 30-foot swaths, broadcasting at 5 gallons per acre.
A ULV Widecast nozzle system is mounted on the back of an ATV or Argo, allowing utilities to put out 25- to 30-foot swaths, broadcasting at 5 gallons per acre.
“Some customers using the Widecast application method have seen up to 95 percent control of targeted vegetation. This is an excellent method for managing the ROW for future low-profile ULV backpack applications,” Lentz said.
Arborchem combines Arsenal herbicide, from BASF Professional Vegetation Management, with the ULV method. Utilities using ULV and THINVERT with Arsenal have achieved control of vegetation that typically re-sprouts one year after mowing. They benefit from the improved reliability and also appreciate that the ultra low volume control method is less visible within communities and creates less impact on desirable wildlife and plants in the ROW areas.
One such customer is Great River Energy, a generation and transmission cooperative based in Elk River, Minn., which manages 80 miles of ROW. In July 2005, Lentz and Keith Erickson, manager of Asplundh operations in Minnesota and parts of the Dakotas, demonstrated the backpack and ATV methods of application to vegetation management specialists from the utility.
Great River Energy tested the ULV technique and THINVERT using a mixture of Krenite, Escort and Arsenal. Managers discovered that ULV provides great control of targeted vegetation and helps maintain ROWs for future low-profile ULV backpack applications.
Other utilities using ULV and THINVERT include Laclede Electric Co-op in Missouri, Pee Dee Electric in South Carolina, American Electric Power (AEP) in Ohio, Exelon in Illinois and Pennsylvania, Oncor in Texas, APS in West Virginia, Rockland Electric in Tennessee and many others.
“During the winter and spring months, I typically give three to four presentations per week as part of the training process for our Asplundh personnel, Arborchem customers and utility vegetation managers,” Lentz said. “And interest is still growing.”
Asplundh credits its co-op and investor-owned utility partners across the U.S. with helping to develop and test the ULV application technique. Asplundh’s collaboration with its customers has allowed them to test ULV techniques in real-world situations. Managing vegetation in ROW corridors helps guarantee transmission reliability and preserve healthy wildlife habitat. These methods of herbicide application-low-volume and ultra low-volume-assist utilities in maintaining their robust transmission systems, ensuring that power continues to flow to customers with less interruption.
Joel Roehl, vegetation specialist with BASF Professional Vegetation Management, works with BASF customers in Minnesota, North Dakota, South Dakota and Montana. Roehl has a masters degree in weed science from North Dakota State University and a bachelors degree in crop and weed science and plant protection from North Dakota State University.