Good machine management cuts operating expenses, extends landfill life for yakima county

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Courtesy of Waste Advantage Magazine

Millions of years past, according to geologists, volcanic eruptions in the Cascade Mountains left widespread deposits of volcanic debris around the southcentral Washington towns of Ellensburg and Yakima. One such deposit, the Ellensburg Formation, has over time become a dense, stubborn soil composed of clay and abrasive rock. For Wendy Mifflin, solid waste manager for Yakima County, and Dan Brulotte, operations manager for the county’s Terrace Heights and Cheyne landfills, the Ellensburg Formation is both benefit and annoyance.

A benefit, says Mifflin, because the soil’s characteristics meet Washington’s regulations for “arid-design” landfills, which require no liner system. The landfill cells are underlaid with clay, she says, and the depth of the area’s ground water is at least 350 feet—and more than 700 feet in some areas. On the other hand, says Brulotte, excavating a new cell or excavating cover material is difficult, typically requiring a ripper tractor to first loosen the soil. Plus, he says, the rocky, abrasive nature of the soil accelerates wear on machines that handle it.

The chore of moving this tough soil falls primarily to Caterpillar’s (Peoria, IL) Cat® 627G scraper, which loads and transports the material after a Cat dozer (either a D9T or D8T) makes a pass with a singleshank ripper. The twin-engine 627G, which develops 630 net horsepower, can self-load in all conditions and hauls cover material up to 2,500 feet to create a stockpile berm that a dozer will later use to cover the face at day’s end.

The scraper works primarily at the 110-acre Terrace Heights site, the county’s principal landfill, located four miles from Yakima. Periodically, the machine is transported 25 miles south to the town of Zillah, where it works on the 125 active acres at the 960-acre Cheyne location. According to Mifflin and Brulotte, the scraper has proved the most cost-effective machine for moving this obstinate material at the landfills, and Yakima County has used such a machine almost from the opening of the sites in 1972.

The county purchased its first scraper for landfill duty in 1975—a Cat 613, which used an elevator-type loading system. The 613 served for seven years; then was replaced in 1981 with an International Harvester 433 dual-engine, open-bowl model. A few years later, the IH was traded on the county’s first 627 (a B Series model), and a 627 has been consistently onsite since.

Managing Operating Costs
Keeping the scraper working productively at low costs in its demanding environment requires careful machine management—a strategy that has evolved over time. Early on, the county recognized the benefit of purchasing on a total-cost-bid basis, which means that the selling dealer performs all preventive maintenance and all repairs for a set per-hour fee, while also guaranteeing a set level of availability.

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