July 14, 2008 | General

Increasing Efficiency At Yard Trimmings Composting Sites

BioCycle July 2008, Vol. 49, No. 7, p. 40
Capital investments such as a stacking conveyor and a larger windrow turner can improve materials handling at larger facilities.

LARGE-scale processors of yard trimmings, wood, land clearing debris and other organic materials are more conscious these days of all the equipment on their sites that run on high-priced diesel fuel. Add to that emissions restrictions and labor costs, and efficiency becomes the name of the game.
The Ketcham Group has operated a 64-acre organics recycling facility in Kings Park, New York since 1997, producing mulch, compost, soil and aggregates such as sand. The facility has made several equipment upgrades, used strategically to increase efficiency. For mulch processing, four-inch minus wood is put into a CBI grinder, which feeds directly into a CEC flat deck screening plant to remove fines (sold as mulch). The flat deck then feeds into another CBI grinder for finished mulch. “We’re finished with grinding and screening in one pass,” says Les Poinelli, Ketcham Group’s Vice President of Operations. “Then the material is moved to a storage location and formed into small windrows so that it can breathe and age.”
The facility had been stockpiling mulch in large piles, but this proved to be problematic. “We would drive on them with a payloader, compressing the material and taking all of the air out, creating ‘sour mulch,'” says Poinelli. To solve the problem, the facility purchased a Yard Dog stacking conveyor from Scotia Machinery two years ago. One month before being sold, mulch is moved from the curing area and dropped into a hopper that feeds the Yard Dog, a stacking conveyor that lifts the material and drops it into a large kidney-shaped pile. “During this last month, the mulch turns into a rich brown finished product, and then it’s shipped out in our fleet of 20 trucks,” he adds.
“With the Yard Dog, we’re taking the same amount of material as before, but the site is run more efficiently,” explains Poinelli. “It uses less gas than the payloaders, less time is spent moving material around, the mulch doesn’t get compressed, and our space is used more efficiently.” He says that they have the same number of employees, but they are now able to attend to other tasks, instead of just managing the mulch.
Brock Harrington of Scotia Machinery in Indianapolis, Indiana notes that the Yard Dog is fed with a 15-yard bucket at 1,000 cubic yards/hour. The stockpile goes up as high as 45-feet. “The conveyor is generally 85 to 95-feet long,” he explains. “The hopper unloads on to a belt that moves 50-feet/minute. That belt feeds a secondary conveyor that moves 500 to 600-feet/minute. Because the density of mulch and compost is low, we can move a lot of material using wider belts.” Harrington adds that one composting facility was able to eliminate a bulldozer and an operator by switching to the stacking conveyor, saving both fuel and labor costs. “The bulldozer burned 10 to 15 gallons/hour of fuel and our machine burns 3 to 4 gallons/hour,” he says.
The Ketcham Group sold about 100,000 yards of classic hardwood mulch in 2007. Some is bagged on site (about one percent) using a Hamer 2080 and an automatic palletizer. In addition, 50,000 yards of colored mulch were sold last year. “We bought an Amerimulch Colortrom last year, and our production level is much higher,” says Poinelli. The colorizer puts out 220 yards/hour, almost double what the facility’s production was before. Besides mulch products, The Ketcham Group produces about 10,000 tons of compost per year, with a mixture of yard trimmings and manure. Local landscapers and contractors pay a tip fee to drop off yard and tree trimmings, leaves and manure from farms.
The City of Greensboro, North Carolina has owned and operated a yard trimmings composting site at its White Street landfill for the past three years. The city took the site over from a private operator, and began evaluating how to improve processing efficiency. The White Street landfill started operations in 1952 and was once on the outskirts of town, but is now surrounded by residential development. Noise was therefore a potential concern, as well as being able to keep piles as aerobic as possible to avoid odor generation. These factors led Greensboro to purchase an ALLU Model AS 38H windrow turner in August 2007, a machine large enough to process the facility’s 32,000 tons/year of yard trimmings, but also quiet, powered by a 450-horsepower turbo diesel engine.
The turner has significantly improved the speed and ease of processing yard trimmings at the White Street facility, turning 200-foot long windrows on a 20.3-acre compacted earth pad. “Operationally, there is less to monitor about the machine’s condition than with our old turner because so much of it is computer-controlled,” says Rob Rash, the Compost Facility Manager. Incoming yard debris is ground by an outside contractor, and then Lewis Walker, the facility operator, uses a yard truck to form windrows, where the material cures for seven to eight months. “I use the ALLU to turn the windrows about twice a week if it’s been raining,” says Walker. “Without rain, I’ll only turn once every two weeks, so that the windrows don’t dry out.”
Capable of turning windrows 10 feet high and 26 feet wide, the ALLU AS 38H is larger than any other unit currently on the market. The center mixing section lifts the material up and over the drum, laying down a thoroughly mixed and fluffed-up windrow that is taller than the original. “This turner is an improvement over our old machine because of the way it fluffs up our windrows to keep air in them,” says Walker. “Plus, I can dial down the drum to get it to within one inch of the ground, so I can gather up and turn all of my windrows and not leave that small unturned area at the bottom.” Finished compost is sold to residents and used by the city for landscaping projects. – R.Y. and N.G.

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