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A survey of facility operations sheds light on expenses to turn grass, leaves and brush into a usable product.
HOW much does it cost to compost and/or process yard trimmings? To come up with specific numbers that reflect variables of volume, treatment and feedstock, public facility managers were surveyed. Agencies were chosen because cost figures are much more readily available from the public than the private sector. However, in contrast to private facilities, most of these agencies do not include land costs in their figures because the site may been owned and even permitted prior to implementation of composting.
Processing costs at the sites ranged from $8/ton to $26/ton. These costs fare well in comparison to disposal fees - but if a public agency is picking up yard trimmings at the curb, it will have added collection costs, which are not included in this report. Throughput of yard trimmings at the sites ranged from 2,000 tons/year to 23,500 tons, with the average around 15,000 tons. The costs reported in some cases are not solely yard trimmings, but an average of all feedstocks.
Interestingly, the least expensive processing reported is at the smallest site. According to many estimates (including a Keep America Beautiful study released in 1995), yard trimmings composting costs go up tremendously with smaller quantities. That would be true if small sites used intensive management of materials. But they often use low-tech methods, and costs are kept to a minimum. Finished compost may be given away to the public or used in public works applications -- which means that shredding and screening may not be necessary. Most municipalities and counties own or have access to a front-end loader, which can be allocated to move materials in windrows.
A statewide survey of yard trimmings composting sites in Iowa identified 51 sites; all but 14 are smaller than 1,000 tons/year, according to Garth Frable of the state Department of Natural Resources (DNR). Of about 150 yard trimmings composting sites in Pennsylvania, only a handful are processing more than 10,000 tons/year.
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In Bozeman, Montana, about 2,000 tons of leaves and grass are collected annually from the city's 27,000 residents. Roger Sicz, street sanitation superintendent, oversaw the construction of a small...