7.5.2.2 Rubber-Tired Machines. Both dozers and loaders are available wit
rubber-tired wheels. Rubber-tired machines are not generally used at sol
waste landfills, since operating conditions can cause tire punctures.
Moreover, the rough spongy surfaces at landfills, combined with reduced
traction and flotation, limit the effectiveness of rubber-tired machines
spreading wastes, grading, and excavating.
Because of its high operating speed, up to 29 miles (47 kilometers) p
hour on solid ground, the rubber-tired loader is suited for carrying cove
material economically over distances of up to 600 feet (180 meters), and
putting cover material into haul trucks. Rubber-tired machines used
extensively on landfills should be equipped with steel-guarded tires (roc
tires). Alternatively, tires can be filled with foam to reduce the
frequency of punctures. Solid waste compaction densities of 900 to 1,100
pounds per cubic yard (530 to 650 kilograms per cubic meter) can be obtai
using a wheel loader.
7.5.2.3 Landfill Contractors. Several equipment manufacturers market
landfill compactors equipped with large trash blades. In general, these
machines are modifications of road compactors and log skidders. The powe
train and structure of landfill compactors are similar to those of
rubber-tired machines, and their major asset is their steel wheels. The
wheels are either rubber tires sheathed in steel or hollow steel cores.
Both types are studded with load concentrators. Rubber-tired dozers and
loaders have also been modified for use as landfill compactors.
Steel-wheeled landfill compactors impart greater crushing and compact
effort than do rubber-tired or crawler machines. A large landfill compac
can reportedly produce in-place solid waste densities of 1,200 to 1,600
pounds per cubic yard (710 to 950 kilograms per cubic meter).
The landfill compactor is an excellent machine for spreading and
compacting on flat or level surfaces and operates fairly well on moderate
slopes, but it lacks traction when operating on steep slopes or when
excavating. For this reason, landfill compactors are best used for
spreading and compacting solid waste and cover material, and an additiona
piece of equipment will be required for soil excavation, hauling, and
spreading. If the cover material is clay, it may become lodged between t
load concentrators (together with solid waste). When this occurs, the
concentrators must be continually scraped with cleaner bars.
7.5.2.4 Scrapers. Scrapers are excellent for earthmoving and excavation
Scrapers are also effective in applying interim and final cover. Because
their tires are susceptible to punctures on landfills, and because of the
low clearance, they are not well suited for applying cover directly over
waste. However, they are useful for applying cover over daily and interi
soil layers. There are three types of scrapers: nonmechanized pulled
scrapers, self-propelled scrapers, and self-loading elevating scrapers.
Pulled scrapers require the use of a track dozer for excavation and
hauling operations. They are most appropriate for use on small landfills
Although pull scrapers are low-production machines, they are inexpensive
purchase and maintain.
5.10-102
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