Newsletter and Technical Publications
<Municipal Solid Waste Management>
This discussion groups landfills into three general
- Open dumps
- Controlled dumps
- Sanitary landfills
Obviously, these three types of landfills are points on a continuum, with
facilities in developing countries most often falling somewhere between open
dumps and controlled dumps. The table on the next page summarizes the main
distinguishing characteristics of each of the three types.
Open dumps and the need to upgrade them
Open dumps have the lowest initial capital investment and operating cost of the
three basic types of landfills in the table. (Such costs can include site
acquisition and some activities carried out by municipal officials.
Additionally, many open dumps start off as controlled dumps and degrade due to
lack of management and other resources. In these cases, the resources expended
on a controlled dump have resulted only in an open dump.)
Due to the low initial costs of open dumps, and lack of expertise and
equipment, these sites are common in developing countries. They pose significant
risks to human health and the environment, especially as MSW becomes more
complex in industrializing countries. In addition, the cost of remediating these
sites can easily exceed their total lifetime capital and operating costs.
Contaminated groundwater may never be returned to usable condition and other
environmental impacts may take many decades to ameliorate. Open dumps attract
numerous birds that feed on the wastes, which can make them more serious disease
vectors than flies or rodents.
The practice of open dumping is a dilemma for the poorer and smaller cities
and towns of developing countries: certainly, this method is not sound practice.
(Note, however, that for very poor countries where cities are near deserts
(e.g., North Africa and the Middle East), unimproved open dumps may conceivably
be considered sound if the savings from not upgrading dumps are used to improve
collection service.) Managers are often told to close open dumps and construct
controlled landfills. The reality of inadequate technical and managerial
resources in many places, however, means that solid waste managers must attempt
to ameliorate open dumping practices and gradually upgrade the sites.
There is now considerable experience in a number of countries with low-cost
methods of such upgrading. Solid waste departments can rent the heavy equipment
necessary to improve the infrastructure and grading of the dump or can
subcontract this work to a private engineering firm. The initial step is the
construction of perimeter drains to catch run-off and leachates; then, the site
should be graded, to minimize leaching through the wastes. Machines can be
rented about every two months to periodically adjust the grading, construct
trenches for the deposit of waste (if advisable), and dig up cover material. The
work of maintaining the grading and applying cover material can then be done
manually by municipal workers. In some cases, a provincial ministry acquires the
necessary earthmoving equipment and it is rotated among the dumps of the
jurisdiction. In cases where equipment is obtained by the authority operating a
dump, such equipment should be kept as simple as possible to make operation and
maintenance feasible. It is important to demonstrate to municipal engineers that
improvements can be made to open dumps with little capital outlay and few
The discussion in the remainder of this section will focus on controlled
dumps and sanitary landfills.