In the Northwestern United States, the Emerald Peoples Utility District (EPUD; Eugene, Oregon) has recognized that trees growing in the wrong place can cause service outages. Whether the interruption is momentary or sustained, it is a menace to customers, and can result in lost revenues and costly trouble calls. Most of EPUD's 600-sq mile service territory contains overgrowth, which encroaches on its 1800 miles of power lines.

Most of the utility's 18,500 predominately rural customers use electricity to pump their water from private wells. So, when the power goes out they have no lights or water.

History

Maintenance operations thought it had a handle on tree trimming, using company crews and outside contractors to keep lines cleared on a five-year rotating program.

Even though EPUD has maintained record-setting reliability, workers were feeling the pressure of Oregon's ideal growing conditions, which was propagating relentless tree growth and a never-ending problem of encroachments and outages caused by trees. At one time, the tree problems were so great that in addition to four or five in-house crews, 12 contract crews were kept busy catching up with the tree growth. Service crews were averaging more than 300 hours a year. Once the crews caught up, the number of contractor crews was reduced, but several new full-time in-house crews were started.

Company Listens

EPUD has always prided itself in being a company open to suggestions. When an employee told management about impressive tree-trimming equipment being used by Seattle City Light and Tacoma Power, EPUD was interested. The grinder/cutter unit being used was doing the work of several trimming crews clearing trees faster and more efficient. EPUD began investigating the possibility of owning and operating larger, more aggressive trimming and clearing equipment.

Equipment Criteria

After visiting with manufacturers and neighboring utilities using grinder/cutter-type units, EPUD determined its situation would require a track-mounted brush and tree cutter with a triple axle trailer. Department of Transportation load limits were an important criteria for selection of the new trimming unit. It needed to be big enough to significantly increase trimming crew's production times but small enough, including the trailer, to meet height and weight limits for over-the-road transporting.

The preferred grinder/cutter unit, called a “Slashbuster” Model XL 480S, manufactured by D&M Machine Division Inc. (Montesano, Washington), was just over 8-ft wide and carried a boom of 15 ft 3 inches. After discussing carrier options with an engineer at Caterpillar, EPUD decided that a Cat 312 C would meet the road limits and adequately perform the work of maneuvering and powering the cutter unit. The Slashbuster mounted on the Cat 312 C loaded on the trailer is just over 70,000 pounds, with a height on the trailer (not a lo-boy) of 13 ft 11 inches.

To address the need to work in the rugged conditions and still be able to cross roads without damaging the surfaces, the track-mounted machine is outfitted with soft cleats. A 10-yd dump truck and a stump grinder with it's own trailer also were recommended, along with other trimming and chipping accessories.

In late 2002, the package was proposed and accepted by the EPUD board. The total cost for equipment and trailers was $300,000. The deciding factor for EPUD to go forward with the more aggressive tree-trimming program was the ambitious goal of being able to clear 300 to 400 spans of ROW per year. This would eliminate two contract crews at $250,000 annually and still be able to keep all ROW cleared on a five-year rotation basis.

More Than Expected

The results have surpassed all expectations. From August 2003 through December 2003, the Slashbuster crew trimmed 19 spans of transmission line and 173 spans of distribution line working 78 working days. As operator efficiency improved, crews cleared 141 spans of distribution line in 30 working days in January and February. In the first 17 working days of March, 80 spans were cleared.

Normally, a three-man trimming crew with a bucket truck and chipper can trim about five spans in four to seven working days, depending on density and terrain. The new cutter unit crew, which includes a foreman, an operator and a trimmer, were able to do four spans in six hours.

The new trimming unit performs more of a tearing and grinding function, mulching trees and brush up to about five inches in diameter. It readily “eats up” blackberry bushes and tag alder vines. Four-foot cutter blades, encased in a safety shroud, rip and tear trees and brush into finely chopped mulch that is returned to earth as nutrients. The stump grinder implemented at the same time is used to inhibit future growth, which for some varieties can be a foot a year and new shoots of 6 to 7 ft. Ideally, most ROW areas should be trimmed every three to four years. With the new equipments ability to cut trees flat with the ground, those numbers are expected to extend the trim cyle to six years.

Overhead Trimming in Concert

The new addition doesn't eliminate the need for standard line clearing crews. Other trimming crews work along side the grinder/cutter from aerial man-lifts, performing side trimming and removal of tree limbs close to power lines. Trees and limbs are dropped into the path of the grinder/cutter unit and shredded into mulch debris. The foreman goes ahead of the trimming crews, addressing fencing and gate issues. With the more thorough cleaning capabilities, landowners and customers are educated on the trimming operation. Wherever possible, private land customers are asked to sign a triplicate-copy release form, which allows EPUD to trim or preferably (stump grid) remove trees in the ROW. Getting permission from landowners in advance has eliminated 99% of the he-said/she-said problems that usually come up after the trimming crew has passed through.

Budget Cutting

Thanks to the employees who suggested looking into the larger trimming equipment, EPUD's annual line clearing budget is $1.5 million, which is $500,000 less than before it purchased the new cutter machine. Crew sizes are smaller, overtime is down and EPUD is ahead of schedule for the first time in clearing ROW.

Regarding a recent clearing job, one manager commented, “You can drive a Cadillac down the ROW now.” Because of the more thorough clearing capabilities, management is talking to the National Wildlife Association about converting some of the spans into a refuge for wildlife. The plan is to work with the wildlife commission and other state agencies in replacing broad leaf vegetation with native grass and ground cover more conducive to native birds.

Coy Kratz is manager of Operations & Engineering for EPUD, where he has worked since it was formed in 1983. Kratz has worked in the utility industry for more than 35 years in successive capacities as a serviceman, line foreman and operations manager. He has been active in Northwest Apprenticeship Training for many years.
coy@epud.org

Al Crocker retired from EPUD in 2003 after 43 years in the utility industry. He was one of the first employees to join EPUD where he held various management positions and was a field troubleshooting technician. During his carrier, he was active in the Northwest Public Power Association, chairing several subcommittees.
al2fish@aol.com