Page 378 - Materials Chemistry, Second Edition

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The Sanitary Landfill 349
10.8 LANDFILL RECLAMATION
Landfill reclamation is a relatively new approach used to expand landfill capacity and avoid the high
costs of acquiring additional land (U.S. EPA, 1997). Reclamation costs may be offset by the sale of
recovered materials such as recyclables including ferrous metals, aluminum, plastic, glass, and the
sale of carbonaceous wastes, which can be burned as fuel. Reclaimed soil can be used as cover
material, sold as construction fill, or sold for other uses. Other benefits of landfill reclamation
include the avoided liability through site remediation, reductions in closure costs, and conversion
of the landfill site for other uses. Reclamation projects have been successfully implemented at
MSWLFs across the United States since the 1980s (U.S. EPA, 1997).
The process of landfill reclamation is summarized as follows: The contents of the landfill cell
are excavated using a bulldozer or front-end loader. A front-end loader then organizes the exca-
vated materials into manageable stockpiles and separates out bulky material such as appliances
and steel cable. A trommel screen (see Chapter 7) or vibrating screens separate soil (including old
cover material) from solid waste in the excavated material. The size and type of screen used
depends on the desired end use of the recovered material. For example, if the reclaimed soil typi-
cally is used as landfill cover, a 2.5 in. screen is used for separation. If, however, the reclaimed soil
is sold as construction fill, a smaller mesh screen is used to remove small pieces of metal, plastic,
glass, and paper.
The separated soil can be used as daily cover in a sanitary landfill. The excavated waste can be
processed at a materials recovery facility to remove valuable components (e.g., steel and aluminum)
or burned in a municipal waste incinerator to produce energy.
In 1986, the Collier County (Florida) Solid Waste Management Department at the Naples
Landfill conducted one of the earliest landfill reclamation projects in the United States. The Naples
facility, a 33 acre unlined landfill, contained MSW buried for up to 15 years. In an evaluation per-
formed on many of the state’s unlined landfills, it was discovered that the Naples Landfill, along
with 27 others, posed a threat to groundwater. City officials formulated a reclamation plan with the
following objectives:

● Decreasing site closure costs
● Reducing the risk of groundwater contamination
● Recovering and burning combustible waste in a proposed waste-to-energy facility
● Recovering soil for use as landfill cover material
● Recovering recyclable materials

A U.S. EPA assessment of the reclamation project found the processing techniques to be effi-
cient for recovering soil but not for recovering recyclables of marketable quality. During a demon-
stration project, the county efficiently recovered a soil fraction deemed environmentally safe. The
45,000 MT (50,000 tons) of reclaimed soil were suitable for use as landfill cover material and as a
medium for plant growth.
In 1990, the Lancaster County (Pennsylvania) Solid Waste Management Authority constructed
a municipal solid waste incinerator to use in reducing the volume of waste entering the Frey Farm
Landfill, a lined site containing MSW deposited for up to 5 years. City officials initiated a landfill
reclamation project to augment the incinerator facility’s supply of fresh waste with reclaimed waste.
The reclaimed waste had a modest heating value (approximately 6,900 kJ/kg or 3,100 Btu/lb). To
achieve a higher heating value, fresh waste, containing wood chips and discarded tires, was mixed
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with reclaimed waste. Approximately 220,000 m (287,000 yd ) of MSW were excavated from the
landfill, and 2,400 MT (2,645 tons) of screened waste were processed per week for the incinerator.
As a result, Lancaster County converted 56% of the reclaimed waste into fuel. The county also
recovered 41% of the reclaimed material as soil during screening (trommeling) operations. The
remaining 3% proved noncombustible and was reburied in the landfill. By the end of the project in