Under normal circumstances, the minimum value of DRASTIC vulnerability
index is 23, the maximum value is 226. Generally, the DRASTIC value is between
50 and 200. The groundwater vulnerability index is relative, and the larger the
value, the more vulnerable the groundwater in this area. According to the
groundwater vulnerability index in typical areas, the groundwater vulnerability is
divided into three levels from large to small:
Level 1: >140, high groundwater vulnerability;
Level 2: 110–140, medium groundwater vulnerability;
Level 3: <110, low groundwater vulnerability.
According to DRASTIC = 5D + 4R + 3A + 2S + 1T + 5I + 3C, the groundwater vulnerability index of the landfill is 124 and the groundwater vulnerability is
medium. The vulnerability degree of the groundwater environment is depended on
the physical nature of the pollutants, besides, the vulnerability of the aquifer itself is
also a very important factor. This project is a Class I construction project and
should be strictly controlled in the whole process of design, construction, material
quality and monitoring.
4. Grading evaluation of the groundwater pollution source intensity
The landfill is an existing anti-seepage pollution source. According to the
evaluation process of groundwater pollution source intensity in Fig. 3.3, the
harmfulness of the pollution source should be taken into account in the evaluation
of groundwater pollution source intensity, and the resistance and control of the
vadose zone should not be taken into account. The grading evaluation results of
harmfulness of groundwater pollution sources are the grading evaluation results of
groundwater pollution source intensity.
According to the investigation results of the landfill, the landfill has a capacity of
7.15 million m
3 and a landfill time of 23 years. The landfill type is mainly domestic
refuse and construction waste, with a leachate production of 10 Â 10
4 m
3 /year.
There are seepage control measures and a leachate collection and treatment system.
Therefore, the landfill capacity score is 10, the landfill time score is 10, the leachate
production score is 8, the landfill type score is 6, the seepage control score is 1, and
the leachate treatment status score is 1. According to Formula (3.1), the pollution
source hazard score is determined to be 7.4872, and the harmfulness of pollution
source is Grade III.
According to Fig. 3.3, the hazard evaluation grade of pollution sources is the
evaluation grade of groundwater pollution source intensity. Therefore, the
groundwater pollution source intensity is Grade III. The site is identified as a
prioritized pollution control site.
250
5 Application Cases
index is 23, the maximum value is 226. Generally, the DRASTIC value is between
50 and 200. The groundwater vulnerability index is relative, and the larger the
value, the more vulnerable the groundwater in this area. According to the
groundwater vulnerability index in typical areas, the groundwater vulnerability is
divided into three levels from large to small:
Level 1: >140, high groundwater vulnerability;
Level 2: 110–140, medium groundwater vulnerability;
Level 3: <110, low groundwater vulnerability.
According to DRASTIC = 5D + 4R + 3A + 2S + 1T + 5I + 3C, the groundwater vulnerability index of the landfill is 124 and the groundwater vulnerability is
medium. The vulnerability degree of the groundwater environment is depended on
the physical nature of the pollutants, besides, the vulnerability of the aquifer itself is
also a very important factor. This project is a Class I construction project and
should be strictly controlled in the whole process of design, construction, material
quality and monitoring.
4. Grading evaluation of the groundwater pollution source intensity
The landfill is an existing anti-seepage pollution source. According to the
evaluation process of groundwater pollution source intensity in Fig. 3.3, the
harmfulness of the pollution source should be taken into account in the evaluation
of groundwater pollution source intensity, and the resistance and control of the
vadose zone should not be taken into account. The grading evaluation results of
harmfulness of groundwater pollution sources are the grading evaluation results of
groundwater pollution source intensity.
According to the investigation results of the landfill, the landfill has a capacity of
7.15 million m
3 and a landfill time of 23 years. The landfill type is mainly domestic
refuse and construction waste, with a leachate production of 10 Â 10
4 m
3 /year.
There are seepage control measures and a leachate collection and treatment system.
Therefore, the landfill capacity score is 10, the landfill time score is 10, the leachate
production score is 8, the landfill type score is 6, the seepage control score is 1, and
the leachate treatment status score is 1. According to Formula (3.1), the pollution
source hazard score is determined to be 7.4872, and the harmfulness of pollution
source is Grade III.
According to Fig. 3.3, the hazard evaluation grade of pollution sources is the
evaluation grade of groundwater pollution source intensity. Therefore, the
groundwater pollution source intensity is Grade III. The site is identified as a
prioritized pollution control site.
250
5 Application Cases