Newsletter and Technical Publications
<Municipal Solid Waste Management>
6.5 Additional considerations
Site remediation falls outside the domain of routine landfill operations.
However, problems may develop at a closed or current site that require the
municipal authority to conduct remedial action. These problems may include
severe leaking of leachate, fires and/or explosions from migrating landfill gas,
unbearable odor, or chronic health problems attributed to the site. Remedial
actions are almost always more costly than prevention.
A commonly used option in carrying out major site remediation is excavation.
Excavation involves the removal of deposited waste from a selected area of the
landfill. If landfill space is scarce, this material may be composted to create
additional disposal space at the landfill. If the objective is a remedial action
in the excavated area, the appropriate corrective action, such as the
installation of a leachate barrier or collection system, may be performed and
the area refilled, compacted, and resealed.
More aggressive remediation technologies are available. These include the
sequestration of groundwater, soil washing, thermal treatment of soil,
vitrification, and the use of microbial agents. The cost of these technologies
is likely to make them unavailable to most developing countries. Their use in
OECD countries is limited and has not been clearly proven to be cost effective.
When emergency remediation is needed to address an acute or chronic threat to
public health in countries with limited resources, urgent appeals should be made
for international assistance. The resident INFOTERRA focal point in the country
is a good source of initial information.
It is useful to think of landfill costs in two categories, capital costs and
operating costs. Capital costs include land acquisition, professional services
for design and the procurement of permits, machinery and equipment purchases,
site preparation and construction, and allocations for CPC operations. Capital
costs can range from 25% to 50% of the total lifetime cost of a landfill. This
is usually paid by a public entity. Depending on the region of the world, this
can be a municipality, a sub-national body, or a national body. Corporations
also finance privately owned landfills.
Careful consideration given to site selection, as discussed above, can
greatly reduce the cost of a landfill. In particular, if a new landfill can be
built to take advantage of natural geological features, the capital cost can be
held down. Controlled dump and sanitary landfill construction will still be
initially more expensive than using open dumps, but properly operated landfill
sites will last longer than open dumps. When the cost of remediation of open
dumps is considered, a landfill can be a realistic, cost-effective alternative.
Operating costs are all costs associated with the day-to-day operation of the
landfill. These range from salaries and wages to equipment maintenance and
repairs. Ideally these costs should be recovered through tipping fees from users
of the landfill. This applies in situations where private operators bring waste
to a publicly operated landfill, or where municipalities bring waste to a large
regional facility. As a general rule, tipping fees should be set to cover only
the operating cost of the landfill. Whether the fees should be set at a higher
level, to cover the amortization of capital costs, is subject to debate. In
areas where there is a significant amount of illegal dumping, fees can be set
lower to discourage such dumping. In such cases, the municipality or other
responsible body would have to cover the landfill operating costs via taxes,
waste collection fees, or intergovernmental transfers.
It is usually necessary to weigh incoming waste to determine the fee to be
charged. An easier alternative is to charge fees based on the volume of waste
that a truck can bring to the site.
In a system that is wholly run by public entities, a landfill's operating
costs can be recovered through taxes, with an appropriation going to the
authority that runs the landfill.
If a large-scale private operator is operating the landfill, public
authorities should ensure the availability of funds for CPC operations by
requiring a performance bond or by holding the company legally responsible for
such costs. This would be a part of the financial assurance requirement.
Waste pickers and buyers
In many countries, waste pickers work on dumps and even landfills, while some
build squatter colonies on the edges of dumps. They gather scraps of food,
clothing, rags, paper, wood, metal, plastic, and other materials and sell them
to buyers who come to the dump site or operate depots nearby. The totally
inadequate living conditions result in major health problems.
From a waste management point of view, access to a landfill should be
restricted to trained personnel and MSW haulers. Landfill operations and
machinery can pose dangers to untrained persons. Fires and explosions from
landfill gas, fainting from exposure to the gas, the possible sudden subsidence
of the fill and the dangers inherent in the waste itself (pathogens, sharps, and
toxic materials) pose additional risks. These risks can be minimized by
excluding unauthorized persons from the site. This includes waste pickers and
the dealers who drive onto dumps.
|This dump in Guatemala is home to 2,000 families.
(credit: Warmer Bulletin)
There is a conflict between the needs of these people and efficient and safe
management of a landfill. Experience in developing countries has shown that it
is not possible to exclude pickers from landfill sites. Compromises are possible
through promoting other options for pickers and buyers. It is preferable that
waste picking occur at transfer stations or at the household level. Transfer
stations are located closer to the city and are therefore more accessible to
pickers. It is also easier to monitor waste picking at transfer stations. In the
absence of pickers, landfill operations can proceed without interruption and
with a reduced risk of injury to members of the public.
If pickers nevertheless persist at landfills, licensing and cooperation
between pickers and municipal staff can help to minimize problems. Allowing
pickers access to sanitary facilities, and providing basic health services such
as vaccinations for infectious diseases and tetanus, will reduce health
problems. This approach has been followed in cities such as Bangkok, Cairo, and
There is a tradition in some countries, including China, of disposing of
garbage directly onto farmland. Farmers seek the nutrient value of the organic
portion of the waste, as long as there is sufficiently little plastic, glass,
and metal in the MSW. This is not a good practice, since uncomposted organic
waste contains pathogens. Regulations in China require farmers to compost the
waste first, but this is often not done. This topic is covered further in the
Composting section of Sound Practices.
Finally, some municipalities dispose of MSW at sea, on land near the ocean,
or on river banks, although many industrialized and developing countries have
banned these practices. In general, these practices cannot be considered
environmentally sound. In Japan, however, an environmentally sound method for
developing landfills in water has been used for some time.