Wherein S stands for the landfill hazard score; bi and and Yi represent
indicator-specific weight and score respectively.
Based on the calculation results of Eq. (3.1), three grades are divided using the
approach of non-equidistant value range (0-10). Hazard reaches Grade I when
S < 4.0, Grade II when 4.0
S < 7.0 and Grade III when S ! 7.0. The greater
the S value, the higher the hazard of groundwater pollution sources.
3.2.2.2 HWLFs
(1) Indicator system
A hazard rating and evaluation indicator system that considers the pollution source
characteristics of HWLFs is constructed, as shown in Fig. 3.5. It includes landfill
volume, landfill period, leachate production, impervious materials and impervious
layer thickness.
(2) Method
The indicator weights and scores for hazard evaluation or environmental risk
assessment of HWLFs are determined using the AHP method, literature reference
and expert scoring method.
(a) Indicator weights and scores
The AHP method is applied to determine the weights of MSWLF hazard indicators,
which involves three steps: to establish the hierarchical structure; to construct
pairwise comparison matrixes; and to calculate the relative weight.
The weights of HWLF hazard indicators are calculated, as shown in Table 3.4,
and their scores are as shown in Table 3.5.
(b) Rating and evaluation
The hazard scoring equation for HWLFs is established based on indicator weights
and scores:
W ¼ a 1 X 1 þ a 2 X 2 þ a 3 X 3 þ a 4 X 4 þ a 5 X 5
ð3:2Þ
Fig. 3.5 Hazard rating and
evaluation indicator system
for HWLFs
3.2 Method of Groundwater Pollution Source Intensity Rating …
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