Environmental Engineering Reference
In-Depth Information
The situation in urbanizing swamp (formerly paddy) areas in tropical mon-
soon countries is entirely different. Under these conditions, the normal situation
involves routine deposition of community refuse into the vacant lands by house-
holders all year around, because the municipal refuse collecting system gives
only partial service. Thus, a great deal of refuse is disposed of by the house-
holders, commercial establishments, and others on a local basis, by throwing it
into the swamp/paddy area or by trucking it there (usually done during the night
hours so the operations are not observed by most people). As a result, the swamp
areas are routinely very heavily polluted with these materials. The groundwater
level during the rainy season is above the surface and often close to the surface
during the dry season. In other words, the surface and shallow groundwaters in
these urbanizing areas are routinely polluted to a high degree by uncontrolled
deposition of refuse.
In addition, excreta also heavily pollute the surface and shallow groundwaters
because excreta disposal is generally by use of subsurface leaching pits, or by
septic tanks with subsurface leaching systems. At Bangkok, because the soils
are generally tight clays, the subsurface leaching systems hardly leach at all;
hence their effluents tend to ooze to the ground surface. At Jakarta, many of
them in the northern city area function poorly because of either tight soils or
high ground water. The result is that even under normal conditions, the surface
and shallow ground waters are very heavily polluted. This situation continues
until the low-lying areas become filled. Usually, this requires a period of years,
ranging from a few years to much longer periods of a decade or several decades.
There is little prospect in the foreseeable future that this situation will change.
Even when the municipal refuse collection system can expand its services, new
areas of building development spring up in the fringe areas on the city outskirts.
Because of the situation just described, the first conclusion, in making the
environmental analysis, is that the “Western rules” are inappropriate for evaluat-
ing the situation on refuse landfilling in low-lying tropical monsoon regions, and
that the analysis, to be appropriate, must be based on the actual local situation.
Parameters for Analysis
Review of the literature on refuse filling practices
in developing countries indicates that the significant parameters involved in eval-
uating the environmental effects of the proposed scheme for systematic swamp
reclamation by refuse landfilling are: (1) sanitation/public health, (2) community
aesthetics, and (3) economics including savings in reclaiming land by the pro-
posed method (with credits for its value for waste disposal) and suitability of the
completed fill for building purposes. Other meaningful considerations applicable
at Bangkok include the impact on local flooding and on the local refuse scavenger
industry.
Sanitation/Public Health/Aesthetics
Under current conditions, the swamp
areas in urbanizing zones arc characterized by very heavy pollution of the shal-
low groundwater, and of surface waters existing during the rainy season, due to
uncontrolled dumping of refuse into these areas and due to excreta waste resid-
uals from subsurface disposal units, which are unable to function effectively.
