Six Sigma: Team whittles down tree trimming costs

(I wrote this article for the Communications and Stakeholder Outreach Department of Aquila, Inc., an energy company based in Kansas City, Mo. This was part of a series of articles that publicized the company’s money-saving Six Sigma projects and appeared on the internal website.)

Team whittles down tree trimming costs

By Rod Perlmutter, Communications and Stakeholder Outreach

Aug. 9, 2006 — On the average work day, 41 contractor crews are trimming trees along the 8,645 miles of Aquila electric lines in Missouri and Colorado. To prevent contractor costs from growing as fast as the trees they trim, a Six Sigma team proposed new ways to analyze productivity and supervise crews.

      The team, headed by Bob Gaw, examined regularly-scheduled tree trimming in the two states, as opposed to emergency work done to correct storm damage. The team found that Aquila spent more than $5.6 million trimming trees in 2005, trimming or removing 504 miles of trees. While that produced tons of firewood, it’s not enough to keep pace with Aquila’s scheduled preventive maintenance, Gaw said. Dropping behind schedule means an increased likelihood that tree growth will interfere with lines and disrupt service.

      The average non-storm-related disruption caused by trees cost the company $556, Gaw said. And the more time spent removing branches that knocked out service, the less time spent doing preventive maintenance.

      This year, the team examined eight crews on eight days at eight sites, measuring time spent getting assignments, traveling to sites, trimming, and other aspects of their jobs. The team found that the actual time spent trimming during an eight-hour shift averaged 4.9 hours.

      Part of the problem, the team said, was using only one supervising forester to communicate daily with 41 crews. The team proposed that Aquila hire three additional foresters. The new supervisors add to payroll, but Gaw said those costs will be dwarfed by increased productivity that will result from better supervision and communication.

      The team said another problem was a lack of clearly stated productivity goals. Among the new goals for each crew is to average 370 feet per day. A trimmed line feet is a linear measurement of branches and wood cut or removed. In 2005, the crews totaled more than 504 trimmed line miles.

      When the Six Sigma team monitored trimming crews a second time, they found better results. The average actual time spent trimming rose to 5.8 hours.

      Another indication of greater activity is the balance between regularly scheduled work and emergency “hot-spotting”. In 2005, about 18,000 man-hours, or about 15% of the trimming budget, was spent on emergencies. For the first six months of 2006, better understanding how tree dollars were being spent dropped the hot-spotting percentage to about 5%.

      “By getting a better grasp on contractor costs, hard savings that result from this Six Sigma project will add to Aquila’s bottom line,” Gaw said.

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