Results and Discussion
Frequency and spatial patterns of open dumps in relation to urban demography
A total of 452 unauthorized dumps spatial pattern analysis was conducted to identify regions
dominated by open dumps. This effort also helped in finding undiscovered dumps while
understanding the propensity for the occurrence or formation of dumps. The population density
and occurrence of open unauthorized dumps were correlated. The core city area has a higher
population density. Core areas with a population den- sity of 5,000-10,000
persons/km2 was found to have open dump sites generally smaller in size and temporary
in nature (Chanakya et al., 2015). Waste composition found at these core city dump sites, it was
found that the organic fraction was quite high shows very recent origin of 1-3 days mainly due to a lack of a regular waste
collection and removal sys- tem. These ephemeral dump sites are cleared at this above frequency
of 2-3 days but recur immediately after their being cleared. These need to be overcome by
adopting a higher degree of coordination between primary collection and trans- portation system.
A larger number of dump sites were found outside of the core area (outskirts and peripheral
areas) wherein population densities ranged between 100 and 1000 persons/km2 (Figure
4). This is comparable to the earlier study conducted in Japan (Tasaki et al., 2007). Areas with
a lower population density tend to have greater number of open dump sites and is evident from
the higher level of occurrenc- es of dumps in localities more than 7 km away from the city
centre (Figure 2). The area within 10 to 20 km away from the city centre had higher number (80%)
of dump sites. This is attributed to availability of common lands, abandoned agri- cultural lands apart from sites that
have lower visibility and proximity. This indicates that as the distance from the city centre
increases, the number of open dumps tends to increase. Large trucks are generally responsible
for the transport of MSW in quantities ranging from 5-8 t/truck load and their disposal to these
specific dump sites. The specific heaps found at these locations bear out that dumper trucks or
vehi- cles of similar capacity are predominantly responsible for these unauthorized dump sites.
At these locations it is not discernible if handcarts and auto tippers carrying out primary
collection at the outer area also dump at their daily collection at such dump sites. This study
and related observations did not implicate them in a significant way. Unauthorized dumps by
these large trucks thus require road access round the year else, it would be impossible for
large garbage trucks to dump their MSW load at locations other than on the roadsides. Fur- ther,
continuous visits on unprepared soil will also create difficulties for trucks to access these
sites on a long-term ba- sis. Earlier study indicated that these trucks generally prefer main
arterial roads during the main part of the journey out of the city and only when they are out of
the denser part of the city these trucks tend to carry out illegal dumping (Ra- jabapaiah,
1988). Assuming this practice still continues, an attempt is made to evolve a relationship
between distance between a major road and the chosen dumps.
The main road network (National Highways, State High- ways and Major District Roads; NH, SH and
MDR, respec- tively) farther away from the city centre had more number of dumps. This is similar
to earlier study findings (Rajabapaiah, 1988). However, now there is a clear region or band
wherein most of the dumping occurs. Generally, areas at a distance of more than 1500 m from the
main road network had higher number of dumps. This phenomenon has been observed in areas located
inside the core city area, outskirts and also, along the peripheral areas (TIDE, 2000). Visual
observations on the size and shape of heaps indicated that this practice of dumping was carried
out predominantly by larger waste col- lection trucks rather than by local residents or by
smaller ve- hicles used in the primary collection process. It is obvious that these heavy trucks
require a pliable road all round the year which can bear the weight of such trucks (10-15 Mg)
and hence, they can reach the dump site they usually dump wastes in. This significantly
restricts the creation of a large number of open dumps at distances more than 1500 m away from
the main road network of the city.
Waste composition at dumps
Out of the total number of locations covered in survey, 44% had a dominant quantity of
construction and demolition wastes. The dominant component of wastes recorded in open dumps was
construction debris, followed by organic wastes and plastic wastes based on the area of spread
and volume of waste present. Organic and plastic wastes occur at 25% and 22% of the dumps. For
dumps located in the core area, as opposed to the peripheral area discussed above, the largest
number of dumps had organic wastes (48%), followed by plastic (26%) and construction debris
(17%) as dominant components. The major contribution outside the core area was from construction debris as observed
in earlier study (Chanakya et al., 2015). This indicated that the dumps studied were in their
last phase of utilization, namely, the stage when the predominant MSW dumped was slowly being
covered up by the next stage of utilization of these dumps by dumping C&D wastes (Chanakya
et al., 2015).
Waste composition at 28 selected dump locations
Figure 5 depicts the segregated components at 28 chosen dumpsites. The overall waste composition
was found to be predominantly 41.3% of construction debris followed by 28.9% of organic waste
and other fractions constituted the remaining. The organic waste fraction was less than the gen-
erated waste in low-density, medium-density and high- density population areas (Speier et al.,
2018). It shows that these sites are at the last phase of waste dumping where C&D waste
provides a good cover or capping to the wastes dumped till this period and second, the presence
of C&D wastes leaves the sites clear for immediate use for realty to commer- cialize
(Chanakya et al., 2015).
Analysis of samples collected at dump site locations shows that moisture content ranges from 1 to
4%, which is extremely low compared to fresh generated waste (Sharma et al., 2019). Total
volatile solids in samples were found to vary from 24 to 93%, while the total carbon content
varied from 8 to 49%. The hydrogen and nitrogen content varied from 1 to 7% and 0.4 to 3%,
respectively. These variations in samples indicate variability in degraded organic fraction of
municipal solid waste as these sites are continuously used from 3-4 years as waste dump sites.
The organic wastes constantly degrade, thereby increasing the relative percentage of inert
components such as plastics and construction debris. Con- struction debris and demolition wastes
are major components of open dump sites that remain visible for a long period as the organic and
recyclable fractions are gradually lost.
Density of wastes accumulated in open dumps
FIGURE 5
Waste composition of dump site locations
Wastes accumulated in open dumps consist of construc-
tion debris, organic wastes, plastic wastes, old wastes, other substances (viz. paper, cloth,
glass, leather, burnt wastes) and rejects from recycling units. Measured densities were 1.01
Mg/m3 (for construction debris), 0.11 (of organic wastes), 0.05 (of plastic wastes), 0.04 (of old wastes), 0.09 (of other substances) and 0.12
Mg/m3 (of recycling rejects), respective- ly. Other wastes include burnt waste which
are extremely fluffy and amenable to secondary dispersal by wind and rainwater. Organic wastes
at this stage is partially dry and lighter than fresh organic waste when collected at the
source. Most of the organic matter that has degraded or dried with time has a low density (0.04
Mg/m3) and is categorized as "old wastes.”
Waste spread area at open dump sites
Waste spread area was estimated at 268 of these locations using GPS to determine area of spread.
The total area of spread was 120212 m2. The land area of open dumps found in the core
area and outside the core area were 2941.45 m2 and 117270.5 m2 (outer
areas 48509.96 m2 and peripheral areas 68760.58 m2), which is equivalent
to 0.02% of total area of Bangalore. The area of waste spread increased from the core to the
periphery of the city as the number of dump sites also increased from inside to the outskirts of
the city.
Height of open dumps
The average height of dumps was 0.69 m. The dump height varied from 0.24 to 1.09 m in the inner
core areas with an average dump height of 0.56 m. The height of the dumps varied from 0.10 to
7.11 m in outside the core area depending upon surrounding area and dumpsite visibility. The
average height of dump in outside the core area is 0.75 m indicating greater accumulation of
waste in the peripheral regions in addition to having a longer residence time.
Quantity of wastes in open dumps
Average waste volume accumulated in 268 dump sites located inside the core area and outside the
core area and pe- ripheral area of the city are 1989 and 102660 m3, respective- ly.
The waste quantity measured is 63652 Mg with a share of 0.5% from core area and rest 99.5% from
outside the core area (42.7% from outer areas and 56.7% from peripheral are- as; Table 1). Table
1 shows that the waste quantity varied for various waste categories. The quantity of waste
dumped was highest in the peripheral area of the city.
The results of this study showed that large open dumps are predominant at locations farther than
1500 m away from the main roads with low population densities (from 100 to 1000
persons/km2) and at a distance of greater than 10 km from the City Centre. The
proximate analysis of samples col- lected at dump site locations confirms the variability in or-
ganic components of municipal solid waste dumped in dump sites. The main component of these
dumps nearer the time of its maturity is construction debris. Considering the average height of
268 estimated open dump sites, total 213310 Mg of waste is dumped in 452 locations. It is
equivalent to 17% of annual MSW generated from Bangalore city and therefore is indicative of the
need to find mechanisms that obviate or overcome the propensity to indiscreet dumping. This
study shows a method to quantity of waste dumped in open disposal sites as well as validate this
data in multiple ways to achieve a higher degree of accuracy and may be extended to other Indian
/developing country situation.