John laing, mass media and misisi areas

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6.1General

The quality of water that we ingest is a critical parameter in determining the overall quality of our lives. In all the project areas, the water that is ingested is from groundwater sources and whose quality has been governed by two major anthropogenic activities, these being the disposal of human excreta and solid waste.

6.2Geologic setting of the misisi and john laing areas

All the project areas are underlain by marble (Fig. 24), which has suffered extreme differential dissolution, resulting in development of a system of subterranean conduits and solution channels (Fig. 25). These features appear to be the major factor controlling groundwater flow in these and most areas underlain by this geological unit in the city.

Fig. 24: Map of the project areas showing the underlying geology

Figure 25: Marble outcrops displaying dissolution features, sometimes below ground surface.

6.3Solid Waste Disposal

The problem of solid waste disposal starts at city level, where it is done at landfill sites usually with very little regard to standard sanitary landfill practices. Overall, the city also suffers from the problems of illegal solid waste dumping only because very few areas of the city are regularly serviced by the Lusaka City Council (LCC), namely parts of the town centre, some low-density residential areas, selected markets, certain governmental and medical institutions. This scenario has arisen at the LCC purely because of inadequate resources but also due to inadequacies in forward planning. For this reason, local communities through various community-based organisations have been involved in solid waste collection and management.

However, except for the Mass Media area, the common practice in these townships is that residents, because of little space within their yards, transfer their waste to the edge of the compounds and/or dump it along the roadsides. In some cases, where these residential areas have space, residents dump their waste in communal areas such as markets or trading areas. If there is some space available within the residents’ yards, pits are dug into which waste is buried.

6.4Excreta Disposal

The methods of excreta disposal in the Misisi and John Laing areas is mainly pit latrines with minor systems of open defecation, pour flush latrines and a limited use of flushing toilets on septic tanks. A number of families that are unable to afford their own latrine do share facilities with three or four other families. In the Mass Media area, there is use of both pit latrines and septic tanks.

6.4.1Septic tanks

These are generally in common use in the Mass Media Complex area. A septic tank functions primarily as a settlement chamber with limited waste digestion (Headworth, 1993). As such, its effluent is generally of poor quality with high ammonia, nitrate, phosphate and faecal coliforms levels. Where a septic tank is emptied timely, it functions efficiently by ensuring that no solid matter is released into environment.

However, vacuum tanker services in Lusaka are greatly overwhelmed by demand in that only about 40 % of the requests are processed in a year. The eminent hazard of the 60 % of unserviced septic tanks is the eventual curtailment in the efficiency of sedimentation and fermentation processes, thereby facilitating overflow and percolation of effluent with pathogenic bacteria and cysts into deeper levels of the ground and subsequently into the aquifer sub horizons.

6.4.2Pit Latrines

Two types of pit latrines are found in the project areas, namely ground level and raised latrines. Raised pits are mainly found in John Laing, where the water table is generally high, particularly during the wet season. However, families that are unable to afford such a structure use either ground level pits or share the facilities with other families. Children in these townships are usually encouraged to use pit latrines from the average age of five, otherwise the most common method noted for the younger children was open defecation.

The ground level pit latrines are often constructed in sinkholes over which residents build some form of a structure made of sacks, plastics, grass or any other available materials (Fig. 26A). As such, the non-raised pit latrines are not built for structural strength but privacy.

On the other hand, the superstructures for raised pit latrines are usually made of blocks (Fig. 26B) and they are either abandoned or the waste is removed when they get full.

Fig. 26: Examples of (A) non-raised pit latrines built mainly for privacy, and (B) raised pit latrines usually made of blocks

An increasingly common practice has been noted in the project areas, where dried up shallow wells are converted into pit latrines in the dry season. Unfortunately, these points have the potential for flooding during the wet season. In many cases, these are constructed in close proximity to water points (Fig. 27A). In addition, some of these excavations have posed other health risks to children, who have ended up falling into these holes and injuring themselves (Fig. 27B).

Pit Latrine

Water point / Shallow well

Fig. 27: (A) Proximity of water supply to latrine, and (B) Child injured from falling into an excavation

The spread of use of pit latrines in relation to the location of water points in Misisi and John Laing as mapped during the execution of this project are given in Fig. 28.

Fig. 28: Distribution of water points and pit latrines in John Laing and Misisi Compounds

As water levels rise near to the ground surface in almost all the project areas during the wet season (November - March), such practices have strong implications for groundwater. This is exacerbated by surface flooding, particularly during excessive rainfall in the wet season to the extent that pit latrines are flooded, thereby posing threats of high concentrations of pathogens infiltrating into the aquifer. In John Laing, such flooding may last for many days during the wet season.

In view of the above scenario pertaining to:

Type of geologic structures in the underlying rocks
The high water levels in the project areas posing a high potential for effluent coming into contact with the water table.
Surface flooding, particularly during excessive rainfall to the extent that pit latrines in these compounds are flooded,
The available data signifying impairment of water quality in these areas,

significant concerns have arisen about the heightening potential of groundwater contamination in the concerned townships due to the possibility of high concentrations of pathogens infiltrating into the aquifer and the potential threats posed to the health of the residents.

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