Only one report on yard waste composting costs was found: a detailed study of capital and operating costs, as well as revenues (Deyle and Hanks, 1991). The study compared composting options in Oklahoma, where landfill tipping fees are low (roughly $8 to $12 per ton).
For a leaf/grass composting facility processing a minimum of 13 tons per day, capital costs were estimated as shown in Table 8.1. The operating costs estimated by Deyle and Hanks, in 1990 dollars per ton of capacity per year, are shown in Table 8.2. Those operating cost estimates include:
Table 8.1 CAPITAL COSTS FOR A LEAF/GRASS COMPOSTING FACILITY PROCESSING AT LEAST 13 TONS PER DAY (1990 Dollars per Daily Ton of Capacity) Land acquisition $915 Land improvements $1,296 Front-end Loader $2,288 Windrow turner $4,958 Portable screen $1,907 Hand tools, etc. $114 Total capital costs $11,478 Source: Deyle and Hanks, 1991 Table 8.2 OPERATING COSTS FOR COMPOSTING PROGRAMS (1990 Dollars per Ton of Capacity per Year) Labor Site attendant $1.92 Equipment operation 2.98 Screen operator 1.19 Gas/oil 0.67 Water 0.13 Materials 0.08 Site/equipment maintenance 1.33 Residual disposal (4%) 0.31-0.50 Total operating costs $8.61-8.80 Source: Deyle and Hanks, 1991 Table 8.3 COMPOSTING COST COMPONENTS (Percent of Total Recycling Program Costs) Yard Waste Yard Waste Collection Composting Processing Revenues Leaves only Best case 43-70 22-36 6-21 4-8 Base case 76-84 11-16 4-10 1 Worst case 85-90 7-9 3-7 0 Leaves and grass Best case 49-72 25-45 2-7 4-9 Base case 66-79 19-28 2-6 1-2 Worst case 79-86 12-17 2-5 0 Source: Deyle and Hanks, 1991Click here for table in WK1 format.
Those costs may be partly or fully offset by revenues from selling all the product or valuing it for municipal use. In the Oklahoma study, Deyle and Hanks (1991) assumed revenues of $0 to $8 per ton, consistent with other materials. Nationwide, revenues ranging from $0 to $25 per ton have been reported (Deyle and Hanks, 1991). However, revenues made up for only a small portion of the costs (see Table 8.3).
For the midrange (base) case program in Oklahoma, Deyle and Hanks (1991) found that the net cost of composting added $1 per household per month above the cost of landfilling the waste. The results would be different for areas with tipping fees of $25-$100 per ton, but the difference would not necessarily be proportional to the difference in tipping fees (Deyle and Hanks, 1991). In areas where tipping fees are higher or compost products have a greater value, composting might be less costly than landfilling.
Published data on MSW composting costs are limited. Capital costs in the range of $40,000 to $80,000 per ton of daily capacity for MSW composting and preprocessing facilities have been reported (Apotheker, l991a).
Figure 8.2 summarizes the capital cost estimates for 12 facilities published as of late 1991 (detailed costs are presented in Exhibit I)(1). Capital costs range from $21,600 to $73,540 per ton of MSW per day. Figure 8.3 shows the operation and maintenance (O&M) cost estimates for these plants. The average O&M cost is $66 per ton of MSW processed, and the range is $30 to $70 per ton. (Tipping fees range from $15 to $78 per ton.)
The investment costs show no scale effects: Investment is a linear function of capacity within the capacity range of 10 to 1,000 tons per day. O&M costs decline linearly with capacity, but the correlation is quite poor.
Despite the good correlation between investment cost and capacity, some caution is advisable in using the data. In many cases, the sources of the estimates fail to provide sufficient information to convert them to a consistent bases or to judge the reasons for the differences. For example, the finance charge for the capital investment for a given facility would be significantly affected by the prevalent interest rate at the time of project financing, but many sources fail to note that interest rate. Moreover, capital investment in general would be affected by the type and composition of the wastes and the plant site conditions, but many sources fail to provide data on these matters.
Similarly, the O&M costs are affected by site-specific conditions such as labor rates, labor contracts, safety rules, the size of the crew, and so on. Again, information on these factors is rarely provided in the literature. Tipping fees generally reflect the capital and O&M costs of a facility, but in some communities the tipping fee is levied as a tax on all residents. The arrangements for a given facility are rarely described in the sources from which the data presented in this report are derived.
COMPOSTING OF MSW
EFFECT OF PLANT CAPACITY ON CAPITAL INVESTMENT(a)
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