Utility vegetation managers continuously face multiple objectives, including product performance, worker safety, controlling the time and money spent, impact on the environment and the effect on community relations and the utility's image.
For this reason, PECO Energy (Philadelphia, Pennsylvania, U.S.) — which has been at the forefront of changing vegetation management trends for more than 50 years — has resolved many of these problems through encouraging the use of low-volume herbicides by its long-time contractor, Asplundh Tree Expert Co. (Philadelphia).
With 12,500 miles (20,117 km) of distribution lines and 930 miles (1497 km) of transmission lines traversing Pennsylvania and Maryland, PECO supplies power to more than 1.5 million residential and business customers. In addition, PECO faces significant challenges in preventing power outages, especially those caused by overgrown vegetation along roadsides and rights-of-way (R/Ws).
Ultra-low-volume (ULV) applications of herbicides is the best and most recent development in vegetation management, and PECO continues to study their uses. ULV herbicide applications require less solution for effective control. In addition, they're more targeted, cost less and deposit less material into the environment.
Testing ULV Herbicides
In April 2000, PECO initiated a test of ULV herbicide usage with a cut stubble application along 500-kV transmission line running from Peach Bottom to Keeny, an area with high-density brush that stretches from Pennsylvania to Maryland. Prior to application, PECO provided training for field operators. Soon after the mowing was complete, crews used two all-wheel-drive ATVs, each equipped with two Widecast nozzles, to cover a 25-ft (7.6-m) swath. PECO applied herbicides at a rate of 2 quarts (1.9 liters) of Tordon K, 1 pint (0.47 liters) of Arsenal herbicide and 4.5 gallons (17 liters) of Thinvert RTU per acre. The ULV herbicide, which was custom-mixed and delivered to the site ready to use, was applied up to 10 ft (3 m) from the edge. Crews mowed a control area, but did not treat it with herbicide, and maintained it to gauge the effectiveness of the herbicide use.
Applying the ULV herbicide with the Widecast nozzles produced more than 95% control of woody vegetation. Using ATVs to drive over the mowed stubble (which enhanced ATV operator safety and visibility) made the application faster — 4 to 5 acres (1.6 to 2 hectares) an hour — than it would have been using other methods. At the two-year mark, the area doesn't require any follow-up, with the exception of the herbicide-free control area.
“The cut stubble area treated with herbicide still looks good,” says Chuck Sheppard, PECO's Vegetation Management Department Transmission System project leader. “Where the herbicide wasn't used, the vegetation has resprouted vigorously.”
PECO uses what it's learned from studies such as these to make decisions about the vegetation management program Sheppard oversees. Then Asplundh Tree Expert Co. implements PECO's vegetation management program along the utility's transmission and distribution R/Ws.
Inroads in Vegetation Management
Asplundh continues to use the cut stubble method, mostly in areas with very high-density brush or woody species to reclaim the R/W. This method represents approximately 15% of the total transmission miles maintained by Bob Tasch, a supervisor with Asplundh Tree Expert Co., his crews and a general foreman. The teams mow with a Kershaw equipped with a Bullhog flail mower prior to applying the herbicide in the high-density brush areas. They follow up with an ULV herbicide application incorporating Thinvert RTU, Arsenal herbicide and Tordon K.
Thinvert saves on the amount of product used through its ability to spread more thinly than water. Low-volume applications using Arsenal reduce the total volume of solution per acre, while providing long-lasting, broad-spectrum vegetation control. Arsenal herbicide's active ingredient stops the production of an enzyme — found only in plants, not in animals, insects or other mammals — that encourages the growth and productivity of weeds. It does this by translocating (moving) into the roots of the weed and preventing it from resprouting.
Crews apply ULV herbicides soon after mowing so the root systems will absorb the soil-active solution, preventing new shoots and promoting grasses and other desirable vegetation. Asplundh doesn't leave anything that's been cut untreated, unless it's a control area or a special request.
This process of using the ULV herbicide cut stubble method has enhanced crew productivity by increasing Asplundh's ability to access the transmission corridor for tree trimming activities.
In fact, the vast majority of the areas Asplundh maintains for PECO — 80% — are treated with herbicide (and tree trimming), not mowing. This equates to a year-round operation, applying herbicide to about 300 transmission miles. During the winter months, Asplundh teams use backpack sprayers to make ULV herbicide basal applications. In the summer, teams use ATVs to treat other areas with an ULV herbicide foliar application.
PECO and Asplundh have seen firsthand some of the other benefits of ULV herbicide usage, especially in low-to-medium density R/Ws. However, access problems have occurred as a result of allowing species originally identified as desirable — such as multiflora rose and autumn olive — to grow.
Three invasive exotic species in particular — multiflora rose, autumn olive and mile-a-minute weed — are responsible for the majority of the trouble, including taking over the R/Ws.
All these species grow very rapidly. In fact, the mile-a-minute weed grows to a height of 30 to 35 ft (9 to 11 m) in a single year, producing thousands of seeds per plant. Devoid of any natural pests, the weed can overgrow desirable trees and other vegetation, creating a monoculture. In the Valley Forge National Park in Pennsylvania, it's been flourishing under the PECO transmission lines and in other areas of the park, threatening the native vegetation.
To control these invasive and incompatible species, the teams apply the ULV herbicide via ATVs or backpacks. Each ATV has a small electric pump and two 15-gallon (57-liter) tanks for broadcast applications. Each backpack is equipped with a gun with a Thinvert nozzle for individual stem treatment.
Basal applications of low-volume herbicide have helped prevent the establishment of new trees, which, in turn, has eliminated the need for future tree trimming and removal. PECO used to have trees encroaching into its R/Ws. Now, what PECO is looking at is a base of wildflowers and goldenrod and other desirable herbaceous plants.
A Tradition of Innovation
Asplundh's move to a better way of controlling vegetation began a long time ago. The testing and use of Thinvert and other low-volume applications (for PECO use) began in the early 1980s. A Thinvert-type of emulsion was designed for aerial applications. Then, it was further developed into Thinvert for use in ULV ground applications.
It's a tradition that continues today, with an emphasis on reducing the amount of products placed into the environment. Ten years ago, the company might have put 100 to 200 gallons (379 to 757 liters) of herbicide mix on an acre. Now, it's 4 to 5 gallons (15 to 19 liters) of herbicide mix per acre for an ULV foliar application and up to 8 gallons (30 liters) per acre on a basal application.
The Savings of ULV Herbicides
Asplundh has other ways of reducing the strain on the environment, such as the return-and-refill program it's had in place for the past 10 years. Arborchem Products, a division of Asplundh, mixes the ULV herbicides and sends them in 15-gallon (57-liter) containers to Asplundh vegetation management teams.
The empty containers are returned to Arborchem for repeated refills until they're unusable. At that point, the containers are completely emptied, cleaned and then recycled through the Pennsylvania Department of Agriculture's recycling program. The department shreds the containers, and the materials are then used to make new herbicide containers. The two phases of this environment-saving plan have turned into cash savings for PECO and Asplundh.
When Asplundh didn't reuse containers, it disposed of a few thousand a year. Its return-and-refill program has eliminated 80% to 90% of the waste. Asplundh also has saved on the cost of acquiring new containers because it doesn't use as many. And that's not all.
ULV herbicide applications have meant big savings in time, too, over the high-volume herbicide techniques PECO once used. With high-volume herbicides, Asplundh's crews not only had to mix the chemicals; they had to find the water to do it with. Years ago, that simply meant going to a local stream, but in times of drought, it had become more difficult. Over the years, as the water supply became less readily available, crews had to drive farther distances to find the water needed for the mix. As a result, a lot of time was wasted, not to mention water (up to 4000 gallons [15,142 liters] a week per crew).
The Benefits of ULV Herbicides
ULV herbicides have made the application process convenient in other ways for operators, as well as the public. Using ATVs, backpacks and pickup trucks, Asplundh crews no longer block roadways with their high-volume spray trucks.
Since Asplundh doesn't need to have a large truck parked on the roadside, motorist visibility is unhampered, and the backpack operators don't distract them, because they're so unobtrusive. In addition, the ULV herbicides control vegetation better and longer than mowing, so road signs and shoulders remain easier for motorists to see. Combined, these factors greatly increase public safety.
Controlling vegetation along railroad corridors is another matter. Maintaining worker safety while allowing the trains to roll on schedule requires teamwork. Ingress and egress to complete the work requires communication and the cooperation of SEPTA (Southeastern Pennsylvania Transportation Authority, the local commuter rail-road company) and other railroad companies.
Environmental impact, community relations and company image are other issues for Sheppard, who oversees PECO's transmission R/W clearance program and operates as the team's safety coordinator. New housing developments that back up against transmission lines have been established along PECO R/W corridors. To further complicate matters, property owners along PECO's R/Ws unknowingly plant incompatible species near the utility's distribution and transmission lines. Sheppard and PECO's other vegetation management experts, along with the company's External Affairs Division, spend considerable amounts of time on community outreach to teach homeowners and developers how to “plant the right tree in the right place.”
Neighboring residents also might be concerned about herbicide use near their homes. However, the herbicides rapidly photodegrade and biodegrade in the soil. The ULV herbicide mixes Asplundh uses are also promoting a safer environment through the reduction of drift.
Morgan Smith is a business writer based in Chester County, Pennsylvania, U.S.
PECO Energy and Asplundh Tree Expert Co.
Growing Better Together
When Asplundh Tree Expert Co. was formed in 1928, the Philadelphia Electric Co., known today as PECO, an Exelon Co., was one of its first customers. Initially, the utility hired Asplundh to maintain the utility's line clearance.
Over the years, Asplundh has expanded its services to meet the growing needs of the utility industry, assisting in meter reading, infrared inspection, building transmission lines and more. Since the 1950s, Asplundh has been a part of PECO's herbicide vegetation management program.
For the past 50+ years, Asplundh has maintained a steadfast search for ways to manage vegetation better, more safely and less expensively. PECO has remained as steadfast in its support of Asplundh's efforts and approving the implementation of innovative vegetation management practices.
Today, PECO delivers electricity to 1.5 million businesses and residents in southeastern Pennsylvania, and Asplundh is the largest tree trimming company in the world — two giants who've grown bigger and better together.
Asplundh and PECO
Taking Care of Customers and the Environment
PECO Energy and Asplundh Tree Expert Co. participate in a number of studies and programs to determine the impact of herbicide use on the environment. For instance, the two companies, along with Environmental Consultants Inc., Pennsylvania Power & Light, a Penn State University researcher and various herbicide manufacturers are long-term participants in the Green Lane Study, which investigates the impact of R/W maintenance on the environment.
In the study, which was established in 1986, the different companies' management works together to create diverse research environments that are then studied. One of the study results demonstrated that a dense, herbaceous groundcover with a thick root mass can keep trees from growing in the R/Ws.
The Green Lane Study was patterned after the State Game Lands 33 project, which began in the early 1950s. The Game Lands project was begun when hunters complained of vanishing wildlife. The hunters blamed the construction of a transmission line for a lack of available food for the game. The study determined that there actually was more wildlife on maintained R/Ws near the forest than in the forest itself. The reason? The large trees in the forest had stifled the growth of the small vegetation needed for the wildlife to survive. The conclusion? Herbicide-maintained R/Ws encourage the growth of small vegetation and benefit wildlife. Additional studies continue to be conducted through the program.
Utilities and Others Protecting the Environment
Project Habitat® members and partners recognize the multiple uses of rights-of-way (R/Ws) and work to turn the job of maintaining the R/Ws into a proactive habitat enhancement program. It is the utility companies, their managers and board members who recognize the potential positive impact that habitat enhancement can have. It is vegetation managers, applicators and engineers who see a need to be efficient and economical in what they do, and value and enjoy the environment where they work and recreate.
Project Habitat partners also include organizations such as the National Wild Turkey Federation (NWTF), an organization dedicated to protecting and enhancing wildlife habitats. And this partnership includes the management and staff of the BASF Vegetation Management Group. For more information about the program or to become a member of Project Habitat, call (800) 727-2057.