John laing, mass media and misisi areas

3.8waste disposal practices

1. 
   Wastes are generated as a consequence of the use of earth materials. Thus, it is important to understand the properties of these materials, both individually and in combinations.
   
2. 
   Wastes and contaminants occur in, and travel through the geologic environment. Therefore, it is imperative that the nature of this environment, the transport process, and the potential for the dispersion of contaminants in this environment are understood.
   
3. 
   Most waste management schemes involve the use of geologic reservoirs for containment, or the use of geologic processes for dilution and dispersion of waste materials.
   

3.8.1Disposal of sewage and wastewater

Further, because of a rapidly growing population, even the waterborne sewerage system initially designed for a population of about 300,000 inhabitants, is currently forced to cope with numbers in excess of 600,000 (Nkhuwa, 1996). Consequently, the system is overloaded, resulting in occasional spillage of sewage on the ground surface.

Since most of this spillage occurs over the vulnerable and differentially dissolved marble terrain, it has the likely consequence of percolating quickly down to the water table, thereby posing more threats of contamination to groundwater resources.

Figure 17: The shallow water table situation in Misisi compound

Fig. 18: The (inappropriate) siting and construction of pit latrines in Misisi Compound

3.8.2Disposal of Solid Waste

Table 5: Forms of waste produced in Lusaka on the basis of source of generation

An indication of some types of waste produced by about 130 industries located in the heavy industrial area along Buyantanshi and Mungwi Roads is given in Table 6.

Table 6: Types of industrial activities, wastes produced and potential pollutants generated

Type of industrial Activity	Potential pollutant
Tannery and leather shoe manufacturers.	Chromium, phenols, heavy metals, biological waste, sulphides
Drug manufacturers/suppliers	Drugs
Paint manufacturers	Petroleum products
Detergent manufacturers	Acids and bases
Fertiliser, pesticides and herbicide suppliers/ manufacturers	Phosphates, nitrates & other organic compounds
Food, dairy and tobacco processing	Organic wastes, inorganic acids, detergents
Timber products	Saw dust, paint, solvents, petroleum products, etc.
Refrigerant dealers and plastic manufacturers	Halogen hydrogen compounds
Chemical and cleaning agencies	Inorganic acids and organic compounds
Drink manufacturers (alcoholic and non—alcoholic)	Organic wastes and bases

Source: Gibb (Eastern Africa Limited) Report (1999)

However, only about 10 % of the generated wastes are freighted to ‘designated’ dumpsites each day, with the larger part of the remaining waste being randomly dumped into unofficial sites scattered over the city. Most of these sites are sinkholes and surface depressions, which have formed by either ground collapse or mining activities of in-filling laterite or outright mining of marbles for construction purposes. Even the now abandoned official dumpsite at Libala utilised such dugout solution conduits (Fig. 19). As such, it comprised numerous scattered excavations into which all forms of waste were dumped, and which usually filled-up with water during the rainy season. With the envisaged subterranean channel-network in the marbles underlying these sites, there is little control, if at all, for outward migration of leachate (or wash-outs) from the waste-bedrock boundary into the underlying strata. As water levels in the city aquifer are quite shallow (from about 2 to 13 metres below ground surface) and generally unprotected, leachate from these waste-dumps has the likelihood of finding unhindered and un-attenuated access to the groundwater store (Fig. 20), thereby posing great threats of groundwater contamination.

Fig. 19: Excavations that have been used for the disposal of waste at the Libala dumpsite

Fig. 20: (A) Water pond at the abandoned Libala dumpsite and (B) a Schematic model of leachate migration at the waste-bedrock boundary into the underlying strata.

Since the site was licensed by the Environmental Council of Zambia (ECZ) in 1993 as a temporal site until its closure in February 2001, the Libala dumpsite utilised to tip all types of waste without exception as indicated in Fig. 21.

Since the water table in the area is only about 3 – 15 metres below ground surface there is little doubt that water in these boreholes is also chemically impaired considering that cones of depression created by pumping are capable of tapping leachate as recharge at the edges of these cones of depression. The presence of highly permeable coarse gravels overlying this area exacerbates the problem of contamination in that they have the capacity to permit unhindered access of contaminants to the groundwater store.

In this regard, there is need for quality monitoring of boreholes in the vicinity of the dumpsite, which must generate comprehensive data that will show whether or not the tipping site has had any impact on the quality of groundwater and the severity of this impact.



Industrial waste

Industrial waste



Clinical/Hospital waste

Industrial waste

Clinical/Hospital waste

Fig. 21: Examples of types of waste dumped at the Libala site (showing mainly industrial and clinical/hospital waste)