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 plan of operation for the placement of solid wastes must be prepared. Various
operational methods have been developed, primarily on the basis of field
experience. The methods to fill dry areas are substantially different from
those used to fill wet areas.
4.2.7.1 Conventional Methods for Dry Areas. The principal methods
used for landfilling dry areas may be classified as (1) area, (2) trench, and
(3) depression.
(See Figures 4-2-7A, B, and C.) In addition to these
methods, which usually are used for unprocessed municipal solid wastes,
landfilling using milled (shredded or compressed and baled) solid wastes is
also discussed.
4.2.7.2 Area Method. The area method is used when the terrain is
unsuitable for the excavation of trenches in which to place the solid wastes.
Operationally (see Figure 4-2-7A) the wastes are unloaded and spread in long,
narrow strips on the surface of the land in a series of layers that vary in
depth from 16 to 30 in. Each layer is compacted as the filling progresses
during the course of the day until the thickness of the compacted wastes
reaches a height varying from 6 to 10 ft. At that time, and at the end of
each day's operation, a 6- to 12-in. layer of cover material is placed over
the completed fill. The cover material must be hauled in by truck or earth-
moving equipment from adjacent land or from borrow-pit areas.
4.2.7.3 The filling operation usually is started by building an
earthen levee against which wastes are placed in thin layers and compacted.
The length of the unloading area varies with the site conditions and the size
of the operation. The width over which the wastes are compacted varies from 8
to 20 ft, again depending on the terrain. A completed lift, including the
cover material, is called a cell (see Figure 4-2-7A). Successive lifts are
placed on top of one another until the final grade called for in the ultimate
development plan is reached. The length of the unloading area used each day
shall be such that the final height of the fill is reached at the end of each
day's operation.
4.2.7.4 If a small amount of usable cover material is available at
the disposal site, the ramp variation of the area method is often used (see
Figure 4-2-7B). In this method, solid wastes are placed and compacted as
described for the area method and are partially or wholly covered with earth
scraped from the base of the ramp. Additional soil must be hauled in, as in
the area method. Because of increasing costs and the problems associated with
obtaining usable cover material, the use of the ramp method must be based on a
detailed economic feasibility study.
4.2.7.5 Balefill Method. Operation is similar to the area method
except refuse is compressed and baled then stacked in the area prior to
covering.
4.2.7.6 Trench Method. The trench method of landfilling is ideally
suited to areas where an adequate depth of cover material is available at the
site and where the water table is not near the surface. Typically, as shown
in Figure 4-2-7C, solid wastes are placed in trenches varying from 100 to 400
ft in length, 3 to 6 ft in depth, and 15 to 25 ft in width. To start the
process, a portion of the trench is dug and the dirt is stockpiled to form an
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