4. Source severity evaluation of the informal landfill
(1) Selection of hazard factors
The risk assessment factors considered for the environmental hazard of the waste
pile include: the organic matter content, the closure time and the waste volume of
the landfill site.
① Organic matter content
When the organic matter content in the waste in an informal landfill is less than 5%,
the waste is basically stabilized. According to the investigation results of the
component of waste at informal landfills and that of the products output by different
waste treatment facilities, the organic matter content of the waste is divided into
four levels: less than 5%, 5–10%, 10–20%, and above 20%.
② Landfill closure time
A large number of investigation and studies have shown that the waste retention
time can reflect the state of the degradable pollutants in the landfill. As the waste
retention time increases, the content of degradable pollutants in the dump will
gradually decrease, and the harmful degree decreases with it. For this reason, the
landfill closure time is divided into four levels: less than 3 years, 3–5 years, 5–
10 years, and more than 10 years.
③ Landfill waste volume
The larger the waste volume at the landfill is, the more pollutants the informal
landfill will produce. The scale rating methods widely used at present are:
large-sized landfill: waste volume greater than 50,000 m
3 ; medium-sized landfill:
waste volume between 5000 and 50,000 m
3 ; and small-sized landfill: waste volume
less than 5000 m
3 .
According to survey, there are many informal landfills that have a waste volume
much larger than 50,000 m
3 . Therefore, another level has been added to the above
landfill scale rating, i.e., extra-large-sized landfill with a waste volume greater than
300,000 m
3 . Therefore, there are 4 levels in total, i.e., less than 5000 m
3 , between
5000 and 50,000 m
3 , between 50,000 and 300,000 m
3 , and greater than
300,000 m
3 .
(2) Hazard factors and weights
① Hazard factor score
The scores of various environmental hazardous factors are shown in Table 5.95.
② Hazard factor weight
The weight of each hazard factor is shown in Table 5.96.
5.5 North China
279
(1) Selection of hazard factors
The risk assessment factors considered for the environmental hazard of the waste
pile include: the organic matter content, the closure time and the waste volume of
the landfill site.
① Organic matter content
When the organic matter content in the waste in an informal landfill is less than 5%,
the waste is basically stabilized. According to the investigation results of the
component of waste at informal landfills and that of the products output by different
waste treatment facilities, the organic matter content of the waste is divided into
four levels: less than 5%, 5–10%, 10–20%, and above 20%.
② Landfill closure time
A large number of investigation and studies have shown that the waste retention
time can reflect the state of the degradable pollutants in the landfill. As the waste
retention time increases, the content of degradable pollutants in the dump will
gradually decrease, and the harmful degree decreases with it. For this reason, the
landfill closure time is divided into four levels: less than 3 years, 3–5 years, 5–
10 years, and more than 10 years.
③ Landfill waste volume
The larger the waste volume at the landfill is, the more pollutants the informal
landfill will produce. The scale rating methods widely used at present are:
large-sized landfill: waste volume greater than 50,000 m
3 ; medium-sized landfill:
waste volume between 5000 and 50,000 m
3 ; and small-sized landfill: waste volume
less than 5000 m
3 .
According to survey, there are many informal landfills that have a waste volume
much larger than 50,000 m
3 . Therefore, another level has been added to the above
landfill scale rating, i.e., extra-large-sized landfill with a waste volume greater than
300,000 m
3 . Therefore, there are 4 levels in total, i.e., less than 5000 m
3 , between
5000 and 50,000 m
3 , between 50,000 and 300,000 m
3 , and greater than
300,000 m
3 .
(2) Hazard factors and weights
① Hazard factor score
The scores of various environmental hazardous factors are shown in Table 5.95.
② Hazard factor weight
The weight of each hazard factor is shown in Table 5.96.
5.5 North China
279