Landfill Design & Facilities
A landfill, also known as a dump (and historically as a midden), is a
site for the disposal of waste materials by burial and is the oldest
form of waste treatment. Historically, landfills have been the most
common methods of organized waste disposal and remain so in many places
around the world.
Landfill design may include internal waste disposal sites (where a producer
of waste carries out their own waste disposal at the place of
production) as well as sites used by many producers. Many landfills are
also used for other waste management purposes, such as the temporary
storage, consolidation and transfer, or processing of waste material
(sorting, treatment, or recycling).
Typically, in non hazardous waste landfills, in order to meet
predefined specifications, techniques are applied by which the wastes
are:
- Confined to as small an area as possible.
- Compacted to reduce their volume.
- Covered (usually daily) with layers of soil.
Operations
During landfill operations the waste collection vehicles are weighed
at a weigh-bridge on arrival and their load is inspected for wastes that
do not accord with the landfill’s waste acceptance criteria. Afterwards,
the waste collection vehicles use the existing road network on their way
to the tipping face or working front where they unload their load. After
loads are deposited, compactors or dozers are used to spread and compact
the waste on the working face. Before leaving the landfill boundaries,
the waste collection vehicles pass through the wheel cleaning facility.
If necessary, they return to weighbridge in order to be weighed without
their load. Through the weighing process, the daily incoming waste
tonnage can be calculated and listed in databases. In addition to
trucks, some landfills may be equipped to handle railroad containers.
The use of 'rail-haul' permits landfills to be located at more remote
sites, without the problems associated with many truck trips.
Typically, in the working face, the compacted waste is covered with
soil daily. Alternative waste cover materials are several sprayed on
foam products and temporary blankets. Blankets can be lifted into place
with tracked excavators and then removed the following day prior to
waste placement. Chipped wood and chemically 'fixed' bio-solids may also
be used as an alternate daily cover. The space that is occupied daily by
the compacted waste and the cover material is called daily cell. Waste
compaction is critical to extending the landfill life. Factors such as
waste compressibility, waste layer thickness and the number of passes of
the compactor over the waste affect the waste densities.
A number of adverse impacts occur from landfill design operations.
These impacts can vary and include:
- Fatal accidents (e.g., scavengers buried under waste piles);
- Infrastructure damage (e.g., damage to access roads by heavy
vehicles);
- Pollution of the local environment (such as contamination of
groundwater and/or aquifers by leakage and residual soil
contamination during landfill usage, as well as after landfill
closure);
- Off gassing of methane generated by decaying organic wastes
(methane is a greenhouse gas many times more potent than carbon
dioxide, and can itself be a danger to inhabitants of an area ;)
- Harbouring of disease vectors such as rats and flies,
particularly from improperly operated landfills, which are common in
Third-world countries;
- Injuries to wildlife;
- Simple nuisance problems (e.g., dust, odour, vermin, or noise
pollution).
Environmental noise and dust are generated from vehicles accessing a
landfill as well as from working face operations. These impacts are best
to intercept at the planning stage where access routes and landfill
geometrics can be used to mitigate such issues. Vector control is also
important, but can be managed reasonably well with the daily cover
protocols.
Most modern landfills in industrialized countries are operated with
controls to attempt manage problems such as these.
Development and operation of landfill facilities in South Australia are
activities of environmental significance and must be carried out in
accordance with the Environment Protection Act 1993 (EP Act).
The Guidelines for Environmental management of landfill facilities
(municipal solid waste and commercial and industrial general waste),
January 2007 provide guidance to landfill operators, developers,
planning authorities and regulatory bodies on the site selection,
development, design, construction, operation, closure and post-closure
management of municipal solid waste and commercial and industrial (C&I)
general waste landfill facilities so that they can comply with the EP
Act. |
