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Landfill mining involves the excavation of completed fill to reclaim buried resources and in so doing, reclaim capacity. Potentially recoverable resources include ferrous scrap, soil, and combustible materials that can serve as a waste derived fuel. Landfill mining also can help remediate and upgrade fills that do not meet public health and environmental specifications. A history of landfill mining can be divided into two periods.
PRE-1980
The concept first surfaced in early 1953 in a paper that documented operations at a landfill operated by the City of Tel Aviv, Israel(1) The establishment and conduct of the mining operation was a private undertaking. The arrangement called for the operators of the system to pay the city approximately $1.18 per cubic yard of finished soil amendment. The operator could sell the product at the equivalent of $3.36 to $3.90 per cubic yard. The facility was designed to excavate the waste, and process it for use as a soil amendment.
Excavation equipment consisted of a clamshell and a front-end (bucket) loader. The plant consisted of a series of conveyors and a trommel screen about 21 feet long and 6 feet in diameter, equipped with internal vanes and one inch openings, and rotated at about 13 rpm.
The material was excavated and transferred to a conveyor belt, which transported it to the trommel screen. Material that passed through the screen openings (i.e., "unders") was used as soil amendment. Material retained in the screen ("overs") was transported by conveyor belt to a salvage area where ferrous and other recyclable materials were separated manually.
The soil amendment had a total nitrogen, phosphorus, and potassium (NPK) concentration of approximately 1.4 percent. Although the reclaimed amendment was primarily used in citrus groves, its broken glass content limited its use in other agricultural applications.
The literature indicates that the Tel Aviv operation remained the sole application of landfill mining until the late 1980s. One of the few vocal advocates of landfill mining during the pre-1980 era was Professor McGauhey of the University of California at Berkeley. In presentations made during the 1960s, he repeatedly referred to landfills as resource storage areas that could later be mined.(2)
Two other developments took place during this time that had a bearing on landfill mining. One was the...