Landfill cost considerations

Ankeny, M.D., Coons, L.M., Majumdar, N., Kelsey, J., and Miller, M., Performance and cost considerations for landfill caps in semi-arid climates, in Landfill Capping in the Semi-Arid West Problems, Perspectives, and Solutions, Reynolds, T.D. and Morris, R.C., Eds, Environmental Science and Research Foundation, Idaho Falls, ID, 1997. 

Tables V and VI (11) outline the estimated economics for a 910 and an 1820 tonne per day plant. The product revenue is estimated as 13.23 per tonne of waste. For an 1820 tonne per day plant, there is a net cost of 6.25 per tonne processed. On the surface it would seem that an expensive process does no better than landfilling the municipal solid waste at 6- 8 per tonne. However, an important consideration is that the quantity of unusable solids has been reduced to 16% by weight and less than 5% by volume of the initial waste, a 20-fold decrease in landfill space requirements.

The price of baled HDPE with up to 2% impurities has fluctuated from 7-10 cents/lb two years ago to about 30 cents/lb recently. If the plastic used in the pyrolysis process did not require this limit, the cost could be considerably lower. (Unseparated waste plastic can be valued as low as negative 2 cents/lb, which accounts for landfilling cost or tipping fee.) Consequently, the run with HDPE was repeated, except the plastic was 96 wt% HDPE and 4 wt% waste polyethylene terephthalate from soft-drink bottles. Pyrolysis yields are given in Table 13.1, showing a 385°C- - yield, based on plastic, of 42.4 wt%. 

Most urban waste is collected by private haulers who determine the least cost place of disposal. Attempts to mandate that privately-collected wastes be delivered to a recovery system have met with considerable opposition from both private haulers and landfill operators. One such attempt precipitated litigation that is now awaiting a decision in the U.S. District Court for the Northern District of Ohio. 

This situation severely constrains the ability of energy and materials recovery systems to compete with land disposal operations for the acquisition of urban wastes. Economy in transportation is one potential advantage that energy recovery facilities enjoy relative to land disposal. Because landfill sites are increasingly available only at considerable distance from the urban centers which generate the waste, the costs of transporting the waste is greatly increased. 

The pattern of gas production assumed to be typical of landfill is shown in Figure 6 and is based on that proposed by Farquhar and Rovers (1973). In this figure, no scale is included on the "x"-axis, for e length of time taken for each process will vary considerably from site to site, according to a number of factors including, waste composition and local environmental conditions. Therefore, the timescale over which pollution events can occur as a result of gas migration will also be site dependent and could vary between a few years and more than one hundred years. For effective pollution prevention, it will be necessary to monitor and exen control for a similar time period, with important cost implications. 

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