liner, scoring 4; and the impervious layer thickness (X 5 ) is 2.0 mm for HDPE
geomembrane, scoring 1.
② Hazard classification and assessment of hazardous wastes landfill
According to
W ¼ a 1 Â X1 þ a 2 Â X2 þ a 3 Â X3 þ a 4 Â X4 þ a 5 Â X5;
W ¼ 0:2549 Â 4 þ 0:2133 Â 5 þ 0:2049 Â 10 þ 0:1707 Â 4 þ 0:1562 Â 1
And the calculation result is that the hazard index is 4.9741, classified as level II.
(2) Pollution control classification of vadose zone
① Indexes and scores of pollution control performance of vadose zone
The hazardous wastes landfill site is located in the bedrock fissure zone geologically, and the vadose zone has very weak pollution control performance, graded as
0.
② Indexes and scores of vulnerability of vadose zone
The hazardous wastes landfill site is situated in the bedrock fissure zone geologically, which does not meet the index in the source strength assessment method. The
bedrock fissure zone is high in vulnerability, graded as 0 hence.
The pollution control performance of the vadose zone is low, and is not considered in general grading.
③ Classification of the groundwater pollution source strength
The pollution source strength of the groundwater in the hazardous wastes landfill is
classified as Grade III, based on the hazards level of pollution source strength which
is Grade II and the pollution control performance of vadose zone which is determined empirically to be Grade III according to the above classification results.
5. Assessment of groundwater environmental and health risks in the hazardous wastes landfill
(1) Health risks assessment
① Hazards identification
A total of 5 groundwater monitoring wells are established for the testing of 49
physical-chemical indexes in the landfill, covering the organic, inorganic and other
substances. Risks identification shall be conducted in accordance with the Technical
Guidelines for Risk Assessment of Contaminated Sites (HJ25.3-2014) and the
(Trial) Guidelines for Health Risk Assessment of Groundwater Pollution.
Groundwater in the site will not be used as drinking water. Groundwater pollution health risks are required to be assessed, since the concentrations of some
pollutants have exceeded the values in the Class III national standard for groundwater quality, as can be inferred from the results of Table 5.131. The risks shall be
384
5 Application Cases
geomembrane, scoring 1.
② Hazard classification and assessment of hazardous wastes landfill
According to
W ¼ a 1 Â X1 þ a 2 Â X2 þ a 3 Â X3 þ a 4 Â X4 þ a 5 Â X5;
W ¼ 0:2549 Â 4 þ 0:2133 Â 5 þ 0:2049 Â 10 þ 0:1707 Â 4 þ 0:1562 Â 1
And the calculation result is that the hazard index is 4.9741, classified as level II.
(2) Pollution control classification of vadose zone
① Indexes and scores of pollution control performance of vadose zone
The hazardous wastes landfill site is located in the bedrock fissure zone geologically, and the vadose zone has very weak pollution control performance, graded as
0.
② Indexes and scores of vulnerability of vadose zone
The hazardous wastes landfill site is situated in the bedrock fissure zone geologically, which does not meet the index in the source strength assessment method. The
bedrock fissure zone is high in vulnerability, graded as 0 hence.
The pollution control performance of the vadose zone is low, and is not considered in general grading.
③ Classification of the groundwater pollution source strength
The pollution source strength of the groundwater in the hazardous wastes landfill is
classified as Grade III, based on the hazards level of pollution source strength which
is Grade II and the pollution control performance of vadose zone which is determined empirically to be Grade III according to the above classification results.
5. Assessment of groundwater environmental and health risks in the hazardous wastes landfill
(1) Health risks assessment
① Hazards identification
A total of 5 groundwater monitoring wells are established for the testing of 49
physical-chemical indexes in the landfill, covering the organic, inorganic and other
substances. Risks identification shall be conducted in accordance with the Technical
Guidelines for Risk Assessment of Contaminated Sites (HJ25.3-2014) and the
(Trial) Guidelines for Health Risk Assessment of Groundwater Pollution.
Groundwater in the site will not be used as drinking water. Groundwater pollution health risks are required to be assessed, since the concentrations of some
pollutants have exceeded the values in the Class III national standard for groundwater quality, as can be inferred from the results of Table 5.131. The risks shall be
384
5 Application Cases