Many of the leaves that have been raked and bagged this fall are just starting a trek around the metro area, as far as 40 miles, to give them purpose and keep them out of the landfill.

While some compost leaves in back-yard bins and others let the autumn carpet blow into the woods, in much of the metro area, a far-flung handful of "leaf brokers" take the leaves from garbage haulers and county compost sites and turn them into black gold: compost.

At Anoka County's Bunker Hills site in Coon Rapids, run by Specialized Environmental Technologies (SET), the metro area's largest composter, the leaves are loaded into semi-trailers and hauled to a farmer in Hastings, who processes the stuff himself to plow into his fields. About a quarter of the volume taken away is returned to the site as compost for local use.

Compost, decomposed organic matter, usually leaves and grass, adds nutrients to soil, reduces erosion, improves water retention in sandy soil and loosens clay soil.

Sue Doll, Anoka County's recycling and solid waste specialist, said that while she's glad to support the composting effort, she is troubled by the fuel spent to schlep the leaves from one end of the metro to another.

"The best thing someone can do is to utilize it on their property," she said. "That takes the least amount of energy."

SET co-owner Kevin Tritz noted that the profit margin for a large-scale composting operation is slim because the overhead is high, from land prices to equipment and labor, and, of course, fuel.

The 40-mile run from Anoka County to the Hastings farmer, for example, costs SET about $250 a trip, he said.

Tritz estimated that SET handles about 40 percent of leaves in the metro area, resulting in about 100,000 cubic yards of compost a year. Other composters cover smaller areas. Plaisted Landscape Supply, a specialty soil company, makes about 5,000 cubic yards of compost from Elk River's dropoff site. Composting Concepts of Woodbury makes about 50,000 cubic yards out of leaves from Ramsey and Washington counties.

State law has banned yard waste from landfills since 1990. Many counties encourage homeowners to compost their yard waste, but many people don't do it, Tritz said.

The past month, along with the weeks bridging April and May, are the busiest at SET, which Tritz and his business partner, Kevin Nordby, bought this month from Resource Recovery Technologies Inc.

At its largest composting station, on Hwy. 169, beyond Shakopee, a front-end loader hauls load after load of steaming black compost, last year's leaves, from one section to another. Backed-in BFI and Waste Management trucks shed loads of bulging plastic bags.

Haulers and homeowners take leaves, by the bag or truckload, to one of SET's six metro-area sites. They pay a fee, based on volume and location, for SET to take the waste. Then the yard waste is shipped, to Shakopee or elsewhere. When the compost is done, after six months to a year of curing time, SET sells it at about $10 a cubic yard, to home gardeners, landscapers and to MnDOT, for use in highway landscaping. Tritz said he views the operation as a service to be provided, one of several options to keep leaves out of the landfill.

Anoka County's Doll agrees.

"Ultimately they're making a good product," she said. "It's a really good usage of it. Gone are the days when everyone would throw everything in bags in a pile."

Maria Elena Baca • 612-673-4409