Based on the findings of landfill investigation, indicator-specific scores are
given: 8 for landfill volume (Y1) which reaches 400,000 m
3 ; 10 for landfill period
(Y2) spans 15 years; 8 for landfill type (Y4) as mainly MSW is landfilled; 6 for
maximum leachate production (Y3) which attains 1.46 Â 10
4 m
3 /a; 5 for seepage
control (Y5); and 4 for leachate treatment (Y6) through collection or treatment
system. Using Eq. (3.1), the hazard index of the landfill is calculated to be 7.4277
within the Grade III range.
The groundwater pollution source intensity is rated Grade III, the same as
pollution source hazard in Fig. 3.3. The landfill is classified into priority sites for
pollution control.
Priority should be given to the removal of pollution sources. The way, scope,
and destination that pollution sources are removed should be clearly defined. Where
the pollution sources are non-removable, it is necessary to reduce the emission
source intensity to a larger extent, and impose stricter control requirements for
seepage control measures and on the time of existence of pollution sources.
(5) Health risk assessment of groundwater environment
(a) Health risk assessment
According to the Guidelines for Risk Assessment of Contaminated Sites (HJ25.3–
2014) and the Guidelines for Health Risk Assessment for Contaminated
Groundwater (Trial), the health risk assessment is conducted using the HERA
model.
• Hazard identification
According to the groundwater quality monitoring results, the groundwater fails to
meet the national Grade III standards for some indicators. As drinking is not
supported by groundwater in the hydrogeological units of the landfill, it is necessary
to launch the health risk assessment for groundwater environment. The risk is
measured for pollutants that are harmful to human health or far exceed the limits,
such as chloride, manganese, ammonia nitrogen and fluoride.
• Toxicity assessment
– Carcinogenicity identification
The carcinogenicity of focus pollutants is identified according to the findings of
IARC and IRIS. The IARC system for carcinogenicity classification is preferred,
followed by the US EPA system. The results are as shown in Table 5.67, and four
focus pollutants are identified to be carcinogenic.
– Toxicity values
The toxicity values (reference dose) for carcinogenic factors and non-carcinogenic
factors are drawn from the mentioned database, as shown in Table 5.68.
5.3 Southwest China
221
given: 8 for landfill volume (Y1) which reaches 400,000 m
3 ; 10 for landfill period
(Y2) spans 15 years; 8 for landfill type (Y4) as mainly MSW is landfilled; 6 for
maximum leachate production (Y3) which attains 1.46 Â 10
4 m
3 /a; 5 for seepage
control (Y5); and 4 for leachate treatment (Y6) through collection or treatment
system. Using Eq. (3.1), the hazard index of the landfill is calculated to be 7.4277
within the Grade III range.
The groundwater pollution source intensity is rated Grade III, the same as
pollution source hazard in Fig. 3.3. The landfill is classified into priority sites for
pollution control.
Priority should be given to the removal of pollution sources. The way, scope,
and destination that pollution sources are removed should be clearly defined. Where
the pollution sources are non-removable, it is necessary to reduce the emission
source intensity to a larger extent, and impose stricter control requirements for
seepage control measures and on the time of existence of pollution sources.
(5) Health risk assessment of groundwater environment
(a) Health risk assessment
According to the Guidelines for Risk Assessment of Contaminated Sites (HJ25.3–
2014) and the Guidelines for Health Risk Assessment for Contaminated
Groundwater (Trial), the health risk assessment is conducted using the HERA
model.
• Hazard identification
According to the groundwater quality monitoring results, the groundwater fails to
meet the national Grade III standards for some indicators. As drinking is not
supported by groundwater in the hydrogeological units of the landfill, it is necessary
to launch the health risk assessment for groundwater environment. The risk is
measured for pollutants that are harmful to human health or far exceed the limits,
such as chloride, manganese, ammonia nitrogen and fluoride.
• Toxicity assessment
– Carcinogenicity identification
The carcinogenicity of focus pollutants is identified according to the findings of
IARC and IRIS. The IARC system for carcinogenicity classification is preferred,
followed by the US EPA system. The results are as shown in Table 5.67, and four
focus pollutants are identified to be carcinogenic.
– Toxicity values
The toxicity values (reference dose) for carcinogenic factors and non-carcinogenic
factors are drawn from the mentioned database, as shown in Table 5.68.
5.3 Southwest China
221