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Solid waste dumping: A challenge for Dhaka City Corporation

Q M IQBAL ZAYEDI
***Overall environmental condition of landfill area is extremely vulnerable as all types of pollution are present there. Due to open dumping of waste foul odor and air pollution is dangerously affecting the surrounding people's lives. Rodents are spreading germs and pathogens in the area and the workers of the landfill are highly exposed to hazardous diseases...***
FAST growth of population in Dhaka city has led to serious inadequacy in urban solid waste management. Solid waste is being generated at an accelerated rate, posing increased environmental risks that must be addressed. Rapid growth of industries, lack of financial resources, inadequately trained manpower; inappropriate technology and lack of public awareness are major factors of constraint of solid waste management for this fast-growing metropolis. Due to limited resources and organizational capacity, it is increasingly becoming difficult for DCC to provide appropriate, modern technological and managerial solutions necessary to ensure efficient and appropriate solid waste collection and disposal services for the entire city population. Dhaka City Corporation has been disposing of garbage in Matuail landfill without following any hygienic technique, which tremendously threaten the environment of and public health in the city. This dumping site will also be filled up within a year; therefore DCC requires other dumping sites for future landfill ground. In order to save the city's environment and protect public health from diseases, it is extremely urgent to build up Sanitary Landfills to dump municipal waste hygienically, where solid wastes will be spread out in thin layers, compacted and covered daily with a fresh layer of clay.
Matuail landfill
DCC dumping site at Matuail is located in southern corner of the city. In order to dump municipal wastes 52 acres of land were bought by DCC in the area, from where 13 acres were filled with earth for resettling some people and the rest of the land has been used as a dumping ground. Now DCC plans to buy 20 acres of adjacent land in Matuail for future landfill. However by the year 2006 this extended land will also be filled up. Matuail dumping site is quite isolated but due to open dumping rodents and insects are carrying dangerous germs in the locality and environmental degradation like air and water pollution, ground water contamination are occurring intensely. The nearest community is about 0.5 km from the dumping ground and few fish farms are found right beside.
Environmental conditions: Overall environmental condition of
the area is extremely vulnerable, as all types of pollution are present there. Due to open dumping of waste foul odor and air pollution is dangerously affecting the surrounding people's lives. Rodents are spreading germs and pathogens in the area and the workers of the landfill are highly exposed to hazardous diseases. Municipal waste of the city contains huge amount of moisture and when it gets diluted with extensive amount of inorganic and organic substances, it turns into leachate. A huge amount of leachate percolates through the surface and contaminates the ground water level of the area. Consequently, the
leachate is also polluting the underground aquifers. If this process keeps continuing, the surrounding people who drink and use ground water will be dangerously affected and when the ground water is polluted, it is not so easy to decontaminate the source. Therefore, DCC needs to consider this situation and take immediate steps to build sanitary landfill sites to dump the solid wastes safely.
Sanitary landfill
Modern state-of-the art landfills on geologically suitable sites is lined with clay and plastic before being filled with garbage. The bottom is covered with a second impermeable liner, usually made of several layers of clay, thick plastic and sand. This liner collects leachate and is intended to prevent its leakage into groundwater. Collected leachate is pumped from the bottom of the landfill, stored in tanks, and sent to a regular sewage treatment plant. When full, the landfill is covered with clay, sand, gravel, and topsoil to prevent water seeping in. Sanitary landfills for solid wastes offer certain benefits. Air-polluting open burning is avoided. Odor does not spread in the nearby area, and birds and insects cannot thrive on. If collected properly they can reduce groundwater contamination to a large extent. According to a 1996 EPA study, landfills give off an estimated 36 per cent of all methane gases, and collected methane can be used in
small power plants or in fuel to produce steam and electricity. For taking such step in Bangladesh an intensive study is required. Even if the production of methane is low due to our waste characteristics, still it could be harnessed to generate power only to reduce the facility operating costs of a landfill and contribute to long term sustainability.
Recently after realizing solid waste dumping problem of Dhaka City, a feasibility study was conducted by Sheltech Consultants (Pvt.) Ltd. for primary identification and selection of landfill sites to facilitate DCC. It has been found in
the study that approximately 563 acres of land is required to build sanitary landfill for 10 million people of Dhaka City. To facilitate the dumping process and reduce transportation cost, experts have divided the city into three zones (south, north and west). For each zone dumping sites are selected accordingly at Demra (120 acres), Amin Bazar (142 acres) and Gazipur (Site 1: approximately 3km from Joydevpur cross section where 140 acres of land is available, Site 2: in front of Bangabandhu Agricultural University, Gazipur where about 145 acres of land identified). This division will allow for better-decentralized management of solid waste. Accordingly DCC may set up three zonal Solid Waste Management Centers and also will be able to accommodate about 33.5 lakh people's daily waste from each zone.
A number of factors have been considered in selecting above landfill sites as discussed below. Several sites have identified and evaluated in terms of these factors and most advantageous sites have been selected.
Type of land: Solid waste landfill process can be used as a method of reclaiming derelict land. Therefore the physical characteristics of the land have to be such that the landfill price can be gainfully used to improve usefulness of the land. Naturally low lying land and areas
excavated for earth for various purposes such as brick making, land filling etc, are suitable from this point of view. Selected sites of Demra and Amin Bazar are mostly that type of lands and sites of Gazipur may be excavated for the filling purpose.
Land use plan: The proposed sites should match the intended future use of the land. In this respect, Dhaka Metropolitan Development Plans (1995-2000) have been consulted for selection of the sites. Besides, land filled with solid waste cannot sustain heavy loads for a long period of time without undergoing undesirable settle-
ments. These solid wastes filled also release methane and other flammable gases during decomposition of waste, which may last up to 30 years. Thus the selected lands can be used for construction of parks, playgrounds, golf courses and markets etc. when it is filled and abandoned.
Hauling distance: As the distance of a landfill site from the collection area increases, the time spent on travelling and the fuel consumption increases two folds. Therefore, the sites have been chosen in three different zones of the city to increase vehicle productivity and minimise operating cost.
Volume reduction of waste: Volume reduction of municipal garbage means the processing of compaction so as to decrease the amount of space they occupy. If one ton of waste is compacted by using bulldozer and other compaction equipment, its volume will be only 1 m3. The proposed landfill sites can be used for at least 10 years if volume reduction is done properly.
Preventing water pollution: The city depends on ground water for domestic use and every attempt needs to be taken to prevent ground water pollution. It is difficult to eliminate leachate and is expensive to collect and treat but to establish a sanitary landfill impermeable layers should be provided so that leachate can be collected by pumps and treated in a treatment plant before
discharging to nature. Soil of selected sites has been examined carefully and found to be quite impermeable and clay loomed. Therefore, it will facilitate to provide plastic or concrete layers to prevent ground contamination.
Environmental conditions: During the decomposition process of waste in landfills many gases including methane, carbon monoxide, carbon dioxide, and hydrogen sulfide etc. are produced and some of these gases are highly combustible and inflammable. Therefore, in order to minimize the impacts of gases on the environment, sites have been selected away from residential and industrial developments taking into consideration the local predominant wind directions, which are southeast and northwest. A minimum distance of 100m from the nearest residential, industrial or commercial building to the landfill has been maintained. Landfill sites also attract various birds even if it is well managed. Therefore, minimum distances of 3 km between the airport and selected landfill site has been maintained.
Size of land: There is an initial cost involved in developing a site for sanitary landfill operation. As the size of sites increases, the unit cost of site development decreases. Therefore, large sites, which can be used for about 10 years have been selected.
According to a UN forecast Dhaka had a growth rate of over 4 percent per annum during 19702000 which will continue at a rate close to 3 percent per annum till 2025. Estimates by the Bangladesh Bureau of Statistics project the population of Dhaka at 15 million in 2015 and 20 million in 2025. Under the given prediction, DCC will need more dumping sites for accumulation of huge amount of daily municipal waste after 10 to 15 years.
The newly selected dumping sites will be capable of holding solid waste generated by city dwellers for minimum 10 years and before end of operation of each landfill, DCC should look for other dumping sites for establishing sanitary landfill. However, we can always look forward to new scientific methods of handling Solid Waste Management with reduced land requirements in the future.
QM Iqbal Zayedi, an environmental planner, is working with Sheltech Consultants (Pvt.) Ltd., and also working as a consultant of Dhaka City Corporation.